Magenta Therapeutics Corporate Presentation - September 2021 (NASDAQ:MGTA)

 
Magenta Therapeutics Corporate Presentation - September 2021 (NASDAQ:MGTA)
Magenta Therapeutics
    Corporate Presentation

    September 2021

    (NASDAQ:MGTA)
1 (NASDAQ:MGTA)
Magenta Therapeutics Corporate Presentation - September 2021 (NASDAQ:MGTA)
Forward-Looking Statements

   This presentation may contain forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995 and other federal
   securities laws, including express or implied statements regarding Magenta’s future expectations, plans and prospects, including, without limitation,
   statements regarding expectations and plans for presenting pre-clinical and clinical data, projections regarding our long-term growth, cash, cash
   equivalents and marketable securities, the anticipated timing of our clinical trials and regulatory filings, the development of our product candidates and
   advancement of our pre-clinical and clinical programs, the potential benefits of our product candidates, the timing, progress and success of our
   collaborations, as well as other statements containing words such as “may,” “will,” “could”, “should,” “expects,” “intends,” “plans,” “anticipates,” “believes,”
   “estimates,” “targets,” “predicts,” “projects,” “seeks,” “endeavor,” “potential,” “continue” or the negative of such words or other similar expressions that can
   be used to identify forward-looking statements.

   The express or implied forward-looking statements included in this presentation are only predictions and are subject to a number of risks, uncertainties
   and assumptions, including, without limitation: uncertainties inherent in clinical studies and in the availability and timing of data from ongoing clinical
   studies; whether interim results from a clinical trial will be predictive of the final results of the trial; whether results from pre-clinical studies or earlier clinical
   studies will be predictive of the results of future trials; the expected timing of submissions for regulatory approval or review by governmental authorities,
   including review under accelerated approval processes; orphan drug designation eligibility; regulatory approvals to conduct trials or to market products;
   whether Magenta's cash resources will be sufficient to fund Magenta's foreseeable and unforeseeable operating expenses and capital expenditure
   requirements; risks, assumptions and uncertainties regarding the impact of the continuing COVID-19 pandemic on Magenta’s business, operations,
   strategy, goals and anticipated timelines, Magenta’s ongoing and planned pre-clinical activities, Magenta’s ability to initiate, enroll, conduct or complete
   ongoing and planned clinical trials, Magenta’s timelines for regulatory submissions and Magenta’s financial position; and other risks concerning Magenta's
   programs and operations set forth under the caption “Risk Factors” in Magenta’s Quarterly Report on Form 10-Q filed on August 5, 2021 and its other
   filings made with the Securities and Exchange Commission from time to time.

   In light of these risks, uncertainties and assumptions, the forward-looking statements discussed in this presentation may not occur and actual results could
   differ materially and adversely from those anticipated or implied in the forward-looking statements. You should not rely upon forward-looking statements as
   predictions of future events. Although Magenta believes that the expectations reflected in the forward-looking statements are reasonable, it cannot
   guarantee that the future results, levels of activity, performance or events and circumstances reflected in the forward-looking statements will be achieved
   or occur. Any forward-looking statement included in this presentation speaks only as of the date on which it was made. Magenta undertakes no obligation
   to publicly update or revise any forward-looking statement, whether as a result of new information, future events or otherwise, except as required by law.

2 (NASDAQ:MGTA)
Magenta Therapeutics Corporate Presentation - September 2021 (NASDAQ:MGTA)
The Potential for the One-Time Curative Power of Stem Cell Transplants

   Potential Applicability Across Blood Cancers, Gene Therapies for Genetic Diseases
                                 and Autoimmune Diseases

3 (NASDAQ:MGTA)
Magenta Therapeutics Corporate Presentation - September 2021 (NASDAQ:MGTA)
Magenta – Recent Updates

          Preliminary Results in                                     MGTA-117                                    $86.4M Capital
         MGTA-145 Phase 2 Trial in
            Multiple Myeloma                                        Clinical Plans                              Raise in May 2021

 • First clinical trial to evaluate MGTA-145 +          • MGTA-117 IND is active with the FDA          • Opportunity to welcome a new group of
   plerixafor for stem cell mobilization and                                                             long-term focused investors into the
   collection in a broad multiple myeloma               • Expects to open the Phase 1/2 clinical         Magenta story.
   patient population.                                    trial in Q4 2021
                                                                                                       • Capital boosts balance sheet – ending Q2
 • As of ASCO presentation:                             • The multi-center, open label Phase 1/2         2021 with approximately $207.8 million in
       • Primary endpoint met for stem cell               clinical trial with single-dose escalating     cash, cash equivalents and marketable
         mobilization and collection in all patients      cohorts will evaluate the safety,              securities and expect to fund company’s
         (15/15)                                          tolerability, pharmacokinetics (PK) and        operating plan into 2nd half 2023.
       • Timely and durable engraftment in all            pharmacodynamics (PD) of MGTA-117 as
         transplanted patients (12/12)
                                                          a single agent in relapsed/refractory AML
       • MGTA-145 was well-tolerated
                                                          and MDS patients.
 • Completed enrollment of all 25 patients
   with final clinical data expected in Q4
   2021.

 • Potential for MGTA-145 + plerixafor to
   become first-line, G-CSF-free standard-of-
   care regimen for stem cell mobilization.

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Magenta Therapeutics Corporate Presentation - September 2021 (NASDAQ:MGTA)
Magenta - Key Highlights

           Anticipated 2021                                      Clinical                                          Corporate
             Milestones                                        Partnerships                                        Strengths

 • MGTA-117 IND – Phase 1/2 clinical trial     •   Value-creating, pipeline-expanding               •   Magenta is the only company
   expected to open in Q4 2021.                    partnerships:                                        addressing both mobilization and
                                                                                                        conditioning in stem cell transplant and
 • MGTA-145 Phase 2 autologous study in                                                                 HSC-based gene therapies.
   multiple myeloma – final 25-patient
   clinical data expected in Q4 2021.                  gene therapy         allogeneic transplant   •   Established relationships with top
                                                   in sickle cell disease       in leukemias
                                                                                                        transplant centers in U.S. and Europe.
 • MGTA-145 Phase 2 allogeneic study in
   leukemia – initial data expected Q4 2021.                                                        •   Well capitalized – ended Q2 2021 with
                                                     gene therapy in          gene therapy in
                                                      neuro disease           blood diseases            cash, cash equivalents and
 • MGTA-145 Phase 2 mobilization study                                                                  marketable securities of $207.8M
   in SCD collaboration with bluebird bio to                                                            (includes recently announced $86.4M
   initiate in Q4 2021.                        •   Non-exclusive research and clinical
                                                                                                        capital raise).
                                                   collaborations enable flexibility and
                                                   development opportunities.

                                               •   Magenta retains all product rights.

5 (NASDAQ:MGTA)
Magenta Therapeutics Corporate Presentation - September 2021 (NASDAQ:MGTA)
The Magenta Pipeline

                                                                                                         Clinical Trial
                              Disease Area          Preclinical       IND-Enabling   Phase 1   Phase 2                    Product Rights
                                                                                                          Partners

                            Multiple Myeloma      Autologous Transplant

 Stem Cell Mobilization        Leukemias          Allogeneic Transplant
 and Collection:
 MGTA-145
                           Sickle Cell Disease    Gene Therapy

                               Leukemias          Allogeneic Transplant

 Targeted Conditioning:   Lysosomal Disorders     Gene Therapy
 MGTA-117
                          Hemoglobinopathies      Gene Therapy

                          Autoimmune Diseases
 Conditioning
 Research Platform
                           CAR-T Conditioning

6 (NASDAQ:MGTA)
Magenta Therapeutics Corporate Presentation - September 2021 (NASDAQ:MGTA)
Stem Cell Transplants: Current Global Market and Growth Opportunities

                                                                                                Potential to Enable Future Growth:
               Large Current Global Market:
                                                                                                 >175k Stem Cell Transplants with
             ~90k Annual Stem Cell Transplants1
                                                                                                        All Eligible Patients2

     • One-time potentially curative treatment with decades                              • Opportunity for 100% of eligible patients to
       of proven clinical experience                                                       receive a stem cell transplant
     • But only ~60% of cancer patients, ~34% of genetic                                 • Significant growth opportunities across cancer,               = 10k patients
       disease patients, and ~5% of autoimmune patients                                    gene therapies and autoimmune diseases
       who are eligible receive a stem cell transplant today,                            • Market growth is synergistic across portfolio; each
       in part due to toxic conditioning2                                                  patient may receive multiple Magenta medicines

                  Sources: 1CIBMTR and EBMT Transplant Registry Data (2018); 2Magenta Market Research & Internal Analysis (2020), Data on File.
                  All data in this presentation cited from CIBMTR are preliminary and were obtained from the Center for International Blood and Marrow
7 (NASDAQ:MGTA)   Transplant Research. The analysis has not been reviewed or approved by the Statistical or Scientific Committees of the CIBMTR.
                  The findings are not the opinion of CIBMTR or CIBMTR's funding sources.
Magenta Therapeutics Corporate Presentation - September 2021 (NASDAQ:MGTA)
Three Types of Stem Cell Transplants – Many Diseases
                                 Step 1: Stem Cell                           Step 2: Patient                            Step 3: Patient
                                 Mobilization / Collection                   Conditioning                               Transplant

         1. Autologous
   Stem Cell Transplant
       Myeloma, Lymphomas

          2. Autologous                                       Gene
                                                            modification
          Gene Therapy
            Genetic Diseases

         3. Allogeneic
   Stem Cell Transplant
                  Leukemias
            (AML, MDS, ALL)

                               Stem cells must be mobilized out of the     The patient’s stem cells must be     Stem cells transplanted into patient via
                               bone marrow and collected from the          removed from the bone marrow to      infusion. They engraft in bone marrow
                               blood with a standard process known         make room for the new transplanted   to rebuild blood and immune system by
8 (NASDAQ:MGTA)                as apheresis                                stem cells                           growing into blood cells and platelets
Magenta Therapeutics Corporate Presentation - September 2021 (NASDAQ:MGTA)
Where Magenta’s Product Candidates Fit
                                  Step 1: Stem Cell                           Step 2: Patient                            Step 3: Patient
                                  Mobilization / Collection                   Conditioning                               Transplant

          1. Autologous
    Stem Cell Transplant
         Myeloma, Lymphomas     MGTA-145

                                                               Gene
            2. Autologous                                    modification

            Gene Therapy
                                MGTA-145                                    MGTA-117
             Genetic Diseases

          3. Allogeneic
    Stem Cell Transplant
                                                                            MGTA-117
                   Leukemias    MGTA-145
             (AML, MDS, ALL)

                                Stem cells must be mobilized out of the     The patient’s stem cells must be     Stem cells transplanted into patient via
                                bone marrow and collected from the          removed from the bone marrow to      infusion. They engraft in bone marrow
                                blood with a standard process known         make room for the new transplanted   to rebuild blood and immune system by
9 (NASDAQ:MGTA)                 as apheresis                                stem cells                           growing into blood cells and platelets
Magenta Therapeutics Corporate Presentation - September 2021 (NASDAQ:MGTA)
Magenta Plans to Deliver Clinical Data and Advance Platform

                                       Autologous: Final clinical data Q4 2021                Mobilization and
                                                                                              engraftment;
                                       Allogeneic: Initial data Q4 2021                       disease outcomes

                                       Gene Therapy: To initiate Q4 2021               Mobilization

                                       Anticipate opening study in               Assessment of safety
                                       Q4 2021                                   and PK/PD

                                                           New target identification and
                                                           approaches for cell depletion to enable
                                                           conditioning for autoimmune diseases
                                                           and cell therapies

10 (NASDAQ:MGTA)
MGTA-145
         Program

     (NASDAQ:MGTA)
11 (NASDAQ:MGTA)
The MGTA-145 Opportunity

                                                                                                    MGTA-145 Potential: Rapid, Reliable, Predictable
                        Limitations with Standard-of-Care
                                                                                                     and Well-Tolerated Mobilization & Collection

            5-8 day mobilization and collection process                                               Rapid and reliable: HSCs mobilized and
            with G-CSF +/- plerixafor                                                                 collected in 1 to 2 days
            Cells collected have low numbers of functional
                                                                                                     Mobilizes high numbers of functional HSCs
            HSCs

            Multiple process days drive higher costs                                                 Streamlined process = lower system costs

            G-CSF can cause significant bone pain and other
                                                                                                     G-CSF Free - Favorable safety profile
            safety issues (e.g., splenic rupture, death)

                                                                                          1
            50% decline rate of unrelated allogeneic donors                                          Rapid and safe donor experience

            Gene therapy requires high number of functional
                                                                                                     Applicable for all HSC gene therapies
            stem cells often collected over multiple sessions

            G-CSF cannot be safely used in sickle cell disease                                       Opportunity for sickle cell disease to be
            mobilization                                                                             proof-of-concept for all HSC gene therapies
                   Sources: 1Be the Match Five-Year Strategic Plan (2018)
12 (NASDAQ:MGTA)
                   Note: Actual claims dependent on clinical trial results and FDA-approved label
The MGTA-145 Opportunity: Rapid, Reliable, Predictable and Safe Mobilization
                Can Improve Patient, Physician and System Experience
                      Current Mobilization Regimen: Unpredictable & Inefficient

                              Day       1       2        3       4        5       6       7        8      5-8 days of
                                                                                                          mobilization &
  Autologous              G-CSF                                                                           collection
                                                                                                                                             MGTA-145 + plerixafor
    (Blood
                                                                                                                                                       Target Profile*
   Cancers)           plerixafor                                                                          ~40% of patients
                                                                                                          require multiple
                      Collection                                                                          collections1                                  Day      1       2

                              Day       1       2       3        4       5       6       5-6 days of
                                                                                         mobilization & collection                           MGTA 145 +
   Allogeneic                                                                                                                                 plerixafor
    (Healthy              G-CSF
    Donors)                                                                              ~15% of healthy
                     Collection                                                          donors require multiple                               Collection
                                                                                         collections1

   Sickle Cell                Day       1       2            …            16      17            …            31       32       Up to 32 days to collect
                                                                                                                               sufficient cells for gene therapy
    Disease
                      plerixafor                             …                                  …
     (Gene
   Therapy)                                                                                                                    ~75% of patients require
                     Collection                              …                                  …                              multiple collections2
                   *Certain hard-to-mobilize patient populations may require an additional day of mobilization; claims dependent on clinical trial results and
13 (NASDAQ:MGTA)   FDA-approved label
                   Sources: 1CIBMTR Real-World Data Analysis, Data on File (2020); 2Tisdale et al. Am J Hematol. 2020, 95 (9):E239-242.
MGTA-145 with Plerixafor: Complementary Mechanisms of Action for Mobilization &
                        Collection of Stem Cells for Transplant

        Complementary mechanisms of action
       mobilize hematopoietic stem cells (HSCs)

     MGTA-145 (GroβT)       +            plerixafor
        CXCR2 agonist                CXCR4 antagonist
          Protein                     Small molecule

     • MGTA-145 binds to CXCR2 on neutrophils which
       triggers release of factors that stimulate HSCs to
       easily migrate out of their niche in the bone
       marrow
     • Plerixafor disrupts CXCR4, which anchors HSCs
       to bone marrow stromal cells
     • Together, these actions release large numbers of
       functional HSCs (CD34+CD90+ cells) from the
       bone marrow niche into circulation, where they
       can be collected for HSC transplant

14 (NASDAQ:MGTA)
MGTA-145 Phase 1 Clinical Results: Demonstrated Rapid, Reliable, Predictable and
            Well-Tolerated Mobilization of Functional Stem Cells in Study

                                                                                                                                                                     Grade 2-4 side effects
                                                              50
                                                                                                                                                                 MGTA-145                     G-CSF2

                                                                                                                                                                  1%                          38%
                                               p e/rµuLl ))

                                                              40
                                                                                                                                                                                    vs.
                                        o d (( #

                                                                                                                                  Double the target
                                                              30                                                                  number of stem cells
                          4 i n cbel lols

                                                                                                                                  mobilized in hours                        Well-tolerated1
                                                                                                                                  (compared to 5 days
                                                              20                                                                  minimum with G-CSF
          +
                        lls

                                                                                                                                  or G-CSF + plerixafor)
           S t e mC CDe 3

                                                                                                                                                                   Speed and predictability
                                                              10
                                                                                                                                                                MGTA-145 +                    G-CSF or
                                                                                                                                                                plerixafor1               G-CSF + plerixafor
                                                               0
                                                                   0       2     4      6     8     10    12    14      24                                      88%                 vs.       0%
                                                                       H oPuorss tP oAstd mP le
                                                                                             inistration (hours)
                                                                                                rix a fo r A d m in istra tio n                                 (7 of 8 subjects)

                                                                                                                                                                   Reliable, same-day dosing,
                      Mobilized large numbers of stem cells in                                                                               hours1                mobilization and collection

15 (NASDAQ:MGTA)                                                       Sources: 1MGTA-145 Phase 1 Clinical Data: Goncalves et al. Blood. 2020, 136 (Supplement 1): 31-32;
                                                                       2Pulsipher et al. Blood. 2009, 113 (15): 3604–3611.
Stem Cells Collected from Healthy Subjects in MGTA-145 Phase I: Superior Engraftment,
    Efficient Gene Modification and Mediated Prolonged Survival in Preclinical Models in Study

   >3-fold increase in                                                                     >20-fold increase in                                                                                                                                                   Gene editing rate in
   collection of CD34+CD90+
   functional stem cells
                                                                                           engraftment function
                                                                                                            2 3 -fo ld

                                                                                                                       1000
                                                                                                                                              p < 0 .0 0 1

                                                                                                                                                     1 1 -fo ld
                                                                                                                                                                                                           >90%                                                   engrafted stem cells in
                                                                                                                                                                                                                                                                  preclinical models
                                                                                                                                                    p < 0 .0 0 1
                                         2 .0                                                                                                                                                                              Stem cells can be efficiently
     )
    8

                                                                                                                        800
                                                                                                                                                                                                                         gene-modified and are functional1
     C o lle c t io n Y ie ld ( x 1 0

                                                                                              E n g ra ftm e n t
                                         1 .5
                                                                                                                        600

                                         1 .0
                                                                                                                        400                                                                               100

                                                                                                                                                              2 -fo ld
                                         0 .5                                                                                                                                                              80
                                                                                                                        200                                  p < 0 .0 5

                                                                                                                                                                            P e r c e n t s u rv iv a l
                                                                                                                                                                                                                                                         MGTA-145
                                                                                                                                                                                                                                                         + plerixafor
                                                                                                                                                                                                                                                                          Collected cells
                                                                                                                                                                                                           60
                                         0 .0                                                                               0                                                                                                                                           are more immuno-
                                                0     1        2         3         4   5
                                                                                                                                                                                                                                                                         suppressive and
                                                                                                                                          r
                                                                                                                                MGTA-145 G-CSF

                                                                                                                                                                        r
                                                                                                                                                        )
                                                MGTA-145             G-CSF                                                               fo                                                                40

                                                                                                                                                                      fo
                                                                                                                                                      ys
                                                                                                                                     xa

                                                                                                                                                                   xa
                                                                                                                                                    a
                                                + plerixafor        (5 days)                                                    + plerixafor (5 days)                                                                                                                   prolong survival in
                                                                                                                                    ri

                                                                                                                                                  d

                                                                                                                                                                 ri
                                                          D a y s to c o lle c t
                                                                                                                                le

                                                                                                                                               (5

                                                                                                                                                              le
                                                                                                                                                                                                           20
                                                                                                                                p

                                                                                                                                                             P
                                                                                                                                                                                                                                                                         a GvHD disease
                                                                                                                                          F
                                                                                                                            +

                                                                                                                                          S

                                                                                                                                                                                                                                                       G-CSF
                                                                                                                            5

                                                                                                                                     -C
                                                                                                                        4

                                          Higher number of                                                                                                                                                                                                                    model1
                                                                                                                       -1

                                                                                                                                                                                                            0
                                                                                                                                    G
                                                                                                                   A

                                                                                             Superior engraftment in
                                                                                                                   T

                                                                                                                                                                                                                0   10       20        30         40         50   60
                                        functional stem cells
                                                                                                          G
                                                                                              M

                                              collected1                                       preclinical models1                                                                                                       D a y s P o s t T ra n s p la n t

16 (NASDAQ:MGTA)                                          Sources: 1Magenta Phase 1 Clinical Data: Goncalves et al. Blood. 2020, 136 (Supplement 1): 31-32.
MGTA-145 Phase 2 Clinical Trials: Ongoing and Planned
                            Proof-of-Concept Across Multiple Disease Areas
                                                                                                                           Key Endpoints
               2021 Anticipated Milestones
                                                                                            Safety &                                       Engraftment             Disease
                                                                                                                 Collection Yield
                                                                                           Tolerability                                  (Rate and Durability)    Outcomes
        Multiple
        Myeloma
      (autologous)              Q4 2021: Final clinical data
                                expected
                                                                                                                                                                 Remission and
                                                                                                                                                                   survival

      Leukemias
     (allogeneic –              Q1 2021: Trial started
    healthy donors)
                                Q4 2021: Initial data expected                           De-risked from           De-risked from                                 Remission and
                                                                                           Phase I*                 Phase I*                                     survival; GvHD

       Sickle Cell
        Disease
     (gene therapy)             Q4 2021: Trial initiation

17 (NASDAQ:MGTA)   *Healthy volunteer donors were successfully mobilized and collected in the Phase I study (similar donor population as allogeneic study)
MGTA-145 Phase 2 Multiple Myeloma Clinical Trial Design

 Purpose           Evaluate the safety and efficacy of MGTA-145 in combination with plerixafor for the mobilization of hematopoietic stem
                   cells for autologous transplantation in patients with multiple myeloma

 Design            25-patient, open label, single arm study, Stanford University

                   Broad and clinically representative patient population: patients aged 18-70 with multiple myeloma (MM), eligible for
 Eligibility       transplant per institutional guidelines and within one year of start of myeloma therapy.
 criteria
                   Patients enrolled include patients with risk factors that could impact stem cell mobilization and collection, such as
                   myeloma-directed therapies that are known to impact stem cell collection, previous malignancy treated with
                   chemotherapy and/or radiation, and other co-morbid conditions. Mobilization agents may be less effective in patients
                   with multiple risk factors.

 Endpoints         Primary Endpoint: Collect ≥2M CD34+ cells/kg in up to two days of apheresis
                                        [threshold number of cells for transplant]

                   Key Secondary Endpoints:
                   (a) Collect ≥4M CD34+ cells/kg in up to two apheresis sessions [target number of cells for transplant]
                   (b) Collect ≥6M CD34+ cells/kg in up to two apheresis sessions
                   (c) Time to neutrophil and platelet engraftment
                   (d) Assess engraftment at 30 and 100 days

                   Note: Protocol requires second day of mobilization for collection of 6M CD34+ cells/kg for potential
18 (NASDAQ:MGTA)
                   second transplant (cells beyond 4M CD34+/kg are frozen)
Preliminary Data Show All Myeloma Patients (15/15) as of the Data Cut-Off Date
                                 Met the Primary Endpoint in Up to Two Days of Mobilization and Collection

                                        Stem Cell Collection (over two days*)                                                                     As of the data cut-off date for the ASCO
                         18                                                                                                                       presentation:

                         16
                                                                                                                                                  • All patients (15/15) met the primary endpoint of
                                                                                                                                                    collection of 2M CD34+ cells/kg in up to two
                                                                                                                            Day 1                   days of same-day mobilization and apheresis;
                         14
                                                                                                                            Day 2                   80% of patients achieved this endpoint in one
                                                                                                                                                    day
                         12
  CD34+ cells x 106/kg

                                                                                                                                                  • The median number of stem cells collected on
                         10                                                                                                                         day 1 and 2 (if needed) was 6.3 million CD34+
                                                                                                                                                    cells/kg
                         8
                                                                                                                                                  • Study criteria allowed for a broad clinically
                         6                                                                                                                          representative patient population including
                                                                                                                                                    patients with multiple risk factors for poor
                                                                                                                                                    mobilization
primary 4
endpoint
                                                                                                                                                  • MGTA-145 + plerixafor regimen was well-
                         2
                                                                                                                                                    tolerated, with transient, drug-related Grade 1
                                                                                                                                                    bone or musculoskeletal pain observed in 40%
                         0
                                                                             Patients                                                               of patients
                                   •   Day 2 needed only if day 1 yield < 6 x 106 CD34+ cells/kg
 19 (NASDAQ:MGTA)                  •   Phase 2 study of MGTA-145 + Plerixafor for Rapid and Reliable Hematopoietic Stem Cell (HSC) Mobilization for Autologous Stem Cell Transplant in Multiple
                                       Myeloma – ASCO, June 2021; EHA Congress; June 2021
All Transplanted Patients Successfully Engrafted as of the Data Cut-off Date

                                                                                                                 As of the cut-off date for the ASCO
                                                                                                                 presentation:
    Engraftment Data N=12
    Engraftment, patients                                                     12 (100%)                          • Neutrophil and platelet recovery within
                                                                                                                   transplant expectations in multiple myeloma
    Neutrophil engraftment, ANC ≥ 500 x                                       12.5 days
    106/L, median (range)                                                     (11-15)
                                                                                                                 • Six patients had completed day-100 follow
                                                                                                                   up, with demonstrated durable engraftment
    Platelet engraftment ≥ 20,000 x 106/L, no                                 18 days
                                                                                                                   indicative of a successful transplant
    transfusion in 7 days, median (range)                                     (15-22)

                                                                                                                 • 40% of collected CD34+ stem cells
                                                                                                                   expressed CD90+CD45RA-, a cell
                                                                                                                   phenotype associated with durable
                                                                                                                   engraftment function, substantially greater
                                                                                                                   than G-CSF-mobilized grafts

20 (NASDAQ:MGTA)   •   Phase 2 study of MGTA-145 + Plerixafor for Rapid and Reliable Hematopoietic Stem Cell (HSC) Mobilization for Autologous Stem Cell Transplant in Multiple
                       Myeloma – ASCO, June 2021; EHA Congress; June 2021
The MGTA-145 Opportunity in Autologous Blood Cancers:
         Rapid, Reliable, Predictable and Safe Mobilization with Reduced System Costs

                               annual stem cell
    26,000                     transplants
     for Multiple Myeloma and Lymphomas                                                                                        MGTA-145
     in major global markets1

                                                                                                      Large Existing Market Opportunity:
                                                                                                         • Plerixafor is used in 55% of autologous
    ~40% of patients                                                                                       transplants, with sales of >$240M annually4

    require multiple collections to achieve target stem cell yield                                    Current Process is Unpredictable:
    (after ≥ 5 days of G-CSF and/or plerixafor)2                                                         • Unable to identify poor mobilizers before
                                                                                                           initiation of process
                                                                                                         • Patient experience is burdensome
                    of autologous
    55%             transplants                        $50-100k                                       High System Costs:
                                                       Appx total cost of stem                           • Average cost of mobilization and collection for
     in U.S. currently                                 cell collection for hard-                           autologous blood cancer patients is $30-50k3
     use plerixafor2                                   to-mobilize patients3                             • Up to $50k-$100k for hard-to-mobilize patient

                 Major Global Markets: U.S., Germany, France, U.K., Italy, Spain, and Japan
                          1                                                              2
21 (NASDAQ:MGTA) Sources: CIBMTR, EBMT, and APBMT Transplant Registry Data (2018); CIBMTR Real-World Data Analysis, Data on File (2020);
                 3Magenta Market Research, Data on File (2020); 4Sanofi Sales Data (2020)
                                                                                           Note: Actual claims dependent on clinical trial results and FDA-approved label
The MGTA-145 Opportunity in Allogeneic Blood Cancers:
               Safe Donor Experience, Durable Engraftment and Reduced Risk of GvHD
                               annual stem cell
    15,000                     transplants
    For Acute Myeloid Leukemia (AML), Myelodysplastic
                                                                                                                                   MGTA-145
    Syndromes (MDS), and Acute Lymphocytic Leukemia
    (ALL) in major global markets1

                                                                                                      Large Existing Market Opportunity:
                    of donors
   50%              decline
                                                                                                         • Leukemias and myelodysplastic syndromes are

   of registered stem cell                         100%                                                    common indications for stem cell transplant

                                                                                                      Lengthy & Cumbersome Process for Donors:
   donors decline to donate                        Of unrelated donor
   when called upon2                               transplants in U.S.                                   • At least 5-day process with scheduling and
                                                   coordinated by Magenta’s                                logistical hurdles
                                                   partner, Be The Match                                 • Negative impact on donor participation rates
                 days
                                                                                                      GvHD Remains a Significant Unmet Need
                 minimum
    Time required to complete
    mobilization & donation
                                                   Up to 50%                                          Partnership with Be The Match:
                                                                                                         • Extensive network in coordinating allogeneic
                                                   Of allogeneic transplant                                transplants
    experience
                                                   patients develop GvHD3
                 Major Global Markets: U.S., Germany, France, U.K., Italy, Spain, and Japan
22 (NASDAQ:MGTA) Sources: 1CIBMTR, EBMT, and APBMT Transplant Registry Data (2018); 2Be The Match Five Year Strategic Plan (2018);
                 3CIBMTR Real-World Data Analysis, Data on File (2020).
                                                                                      Note: Actual claims dependent on clinical trial results and FDA-approved label
The MGTA-145 Opportunity in Gene Therapy: All HSC Gene Therapy Products
          Require Collected Stem Cells – Sickle Cell Disease Data as Proof of Concept
                                                       projected annual
   5,000 – 10,000                                      HSC gene therapy
                                                       patients
    across indications by ~2030; in SCD, initial opportunity to treat                                                                                    Gene
                                                                                                                                                       modification
    ~25k prevalent patients with potential expansion up to ~150k1
                                                                                                                         MGTA-145

                  HSC-based                                                                          All HSC Gene Therapies Require Collected Stem
   >25            gene therapies                   ~75%                                              Cells:
   in clinical development                                                                               • Large numbers of cells required
                                                   Of patients with SCD
   (8 in sickle cell disease)2                     require multiple days of                          High Unmet Need:
                                                   stem cell collection3                                 •   G-CSF is not used in patients with SCD because it
                                                                                                             can trigger crises and death
                                                                                                         •   Plerixafor is suboptimal in reliably mobilizing SCD
                                                                                                             patients’ stem cells3
                   of patients
   >70%            with SCD                                                                              •   >70% of SCD patients experience sickle cell crisis
                                                                                                             events during mobilization4
   experience crisis                               Gene therapy company with
   events during                                   the most experience with                          Partnership with bluebird bio:
   mobilization4                                   plerixafor in SCD patients                            • Gene therapy expertise and experience with plerixafor
23 (NASDAQ:MGTA) Major Global Markets: U.S., Germany, France, U.K., Italy, Spain, and Japan Note: Actual claims dependent on clinical trial results and FDA-approved label
                 Sources: 1Analyst reports; 2ClinicalTrials.gov; 3Tisdale et al. Am J Hematol. 2020, 95 (9): E239-242; 4Uchida et al. Haematol. 2020, 105: e500.
MGTA-145 Competitive Positioning

                                                                                   MGTA-145 +       BL-8040 +   Plerixafor +
                                                                                    Plerixafor       G-CSF         G-CSF            G-CSF
                                                                                    (Magenta)       (BioLine)     (Sanofi)
      Target                                                                            CXCR2        CXCR4         CXCR4

      Stage of Development                                                                Ph 2        Ph 3        Approved          Approved

      1 – 2 Day Mobilization & Collection for
      Transplant                                                                            ✓          ×               ×               ×
      Reduced System Costs vs. Current
      Practice                                                                              ✓          ×               ×               ×
      Development in Non-Oncology
                                                                                            ✓          ×              ✓                ×
      Indications                                                                                               (plerixafor only)

      G-CSF Free, Eliminating Risk of Severe
      Bone Pain & Other Side Effects                                                        ✓          ×               ×               ×

24 (NASDAQ:MGTA)   Note: Actual claims dependent on clinical trial results and FDA-approved label
The MGTA-145 Potential Value Proposition

                                                            1-2 days to collect sufficient HSCs for transplant vs.
               Rapid & Reliable                             5-8 days with current options that rely on G-CSF

                    Broad Benefit                                 Potential to achieve cell collection, engraftment and
                    for Patients                                  disease outcomes across a range of indications

                                                                        Improved safety and well-tolerated, allowing for all
                          G-CSF Free                                    patients, including those living with sickle cell disease,
                                                                        to potentially benefit

                                                                              Improved process, shorter time to mobilize translate
                                Operational                                   to overall cost savings and better experience for
                                Efficiency                                    donors & patients

                        We are driving towards most efficient registration path based on Phase 2 data in 2021;
                                          to leverage significant existing market opportunity
25 (NASDAQ:MGTA)   Note: Actual claims dependent on clinical trial results and FDA-approved label
MGTA-117 Program

     (NASDAQ:MGTA)
26 (NASDAQ:MGTA)
The MGTA-117 Targeted Conditioning Opportunity: Eliminate Need for High Intensity
           Chemotherapy Prior to Stem Cell Transplant or Gene Therapy

     High-Intensity Chemo Conditioning Negatively Impacts Access & Outcomes

                   Oncology Patients              HSC Gene Therapy Patients
                      (Allogeneic)                           (Autologous)

         ▪ Current choice: physicians/patients   ▪ Busulfan (chemo) conditioning can
           must decide between long-term           cause long-term infertility and
           efficacy vs. toxicity                   cancer

         ▪ Need to reduce relapse and extend     ▪ Need to replace busulfan
           survival
                                                 ▪ Opportunity to expand HSC gene
         ▪ Opportunity to expand transplant        therapy use across eligible patients
           across eligible patients

27 (NASDAQ:MGTA)
The MGTA-117 Targeted Conditioning Opportunity: Eliminate Need for High Intensity
        Chemotherapy Prior to Stem Cell Transplant or Gene Therapy
                                      Oncology Patients                                                                 HSC Gene Therapy
                                               (Allogeneic)                                                             Patients (Autologous)
                            Myeloablative                                 Reduced-Intensity                                               Busulfan
                            Conditioning                                  Conditioning                                                    Conditioning

                         Efficacy1:                                     Efficacy1:                                               Efficacy2:
                         86% relapse-free*                              52% relapse-free*                                        >90% stem cell depletion
                         Safety1:                                         Safety1:                                               Safety3:
                         16% treatment-                                   4% treatment-                                          Broad organ damage and
                                                                          related mortality*                                     long-term risks
                         related mortality*

                       MGTA-117
                      MGTA-117                                    Desired Clinical Profile:                                        MGTA-117
                                                                                                                                    MGTA-117

                             +
                           Reduced-Intensity
                                                                       Efficacy             Safety                             Desired Clinical Profile:
                                                                                                                                     Efficacy       Safety
                           Conditioning

                 *Relapse and treatment-related mortality rates at 18 months
28 (NASDAQ:MGTA) Sources: 1Scott, BL. Biol Blood Marrow Transplant. 2017, 26 (3), S11; 2Westerhof et al. Cancer Res. 2000, 60 (19), 5470-5478;
                 3BUSULFEX Package Insert (1999).
Targeted Patient Conditioning Through MGTA-117 Antibody-Drug Conjugate

                                            Target:
                                       Selective binding
                                        to target cells

                                                                                       MGTA-117

     MGTA-117
                                            Payload

   Conditioning                             Payload:
                                            Amanitin
                                         Potent removal
                                          of target cells

                          Engineering:
                       Rapid clearance of the
                        ADC from the body                   MGTA-117 binds to CD117 which is expressed selectively on
                                                            stem cells in the bone marrow and is taken up inside the cell.
                                                            The amanitin payload is released and causes cells to be
                                                            quickly depleted.
29 (NASDAQ:MGTA)
Pre-Clinical Data With Anti-CD117 ADCs Support
                                                                  Development for Transplant Conditioning

                                    Amanitin CD117 ADC
                                                                                                                                                      Single Dose of Tool Anti-CD117 ADC
                               Payload Class Potently Depleted

                                                                                                       11
                                                                                                                                                   Selectively Depleted Stem Cells in Primates
                                 Human Stem Cells in vitro

                                                                                                                HOURS
       % Viable Human HSCs

                                                                               Unconjugated Anti-CD117
                                                                               Microtubule Inhibitor
                             100                                               Immunotoxin             half-life clearance time
                                                                               Amanitin
                                                                                                       compared to
                              50
                                                                                                                    60            HOURS
                               0
                               10 -13 10 -12 10 -11 10 -10 10 -9 10 -8 10 -7                           Anti-CD117 ADC engineered to
                                          Concentration [M]
                                                                                                       enable transplant window
                               Naked anti-CD117 antibody                                               compared to 60 hours for
                               Ribosomal Inhibitor
                               Microtubule Inhibitor                                                   regular antibodies
                               Amanitin

     ✓                       Anti-CD117 amanitin ADC                                              ✓      Cleared quickly in primates to
                             robustly depleted human stem                                                enable target dosing window                ✓   Robustly depleted stem
                                                                                                         prior to transplant2                           cells in primates
                             cells in vitro1

30 (NASDAQ:MGTA)                        Sources: MGTA-117 Pre-Clinical Data: 1Pearse et al. Biol Blood Marrow Transplant. 2020, 26 (3): S35-S36;
                                        2Boitano et al. Bone Marrow Transplantation. 2020, 55: 73.
Pre-Clinical Data with Anti-CD117 ADCs Demonstrated Single Dosing Enabled
               Successful Transplant Without Side Effects and Removed Tumor Cells

                                                                    Side Effect                                         Busulfan               MGTA-117
                                                                                                                                                                        •   Non-GLP tox studies of
                                                                    Veno-occlusive Disease                                 yes                     ⎼                        MGTA-117 vs separate
                                                                    Wasting Syndrome                                       yes                     ⎼                        busulfan data;
  Primate                                                           Diarrhea                                               yes                     ⎼                    •   MGTA-117 well
                                                                                                                                                                            tolerated with none of
                                                                    Mucositis                                              yes                     ⎼                        the side effects of
                                                                    Seizures                                               yes                     ⎼                        chemotherapy2
                                                                    Emesis                                                 yes                     ⎼
                                                                    Pulmonary Fibrosis                                     yes                     ⎼
                                                                                          Reduction of leukemia tumors in mice
                                                                                                                                                     Survival
                                                                                                                                 Treatment
                                                                                         100                                                     (% alive at Day 100)

                                                                     Human tumor cells   75
                                                                                                                                 PBS Control
                                                                                                                                 Chemo
                                                                                                                                                          0
                                                                                                                                                          0             •   MGTA-117 efficiently
               Gene marking @ 1-6 months                                                                                         Control ADC              0
                                                                                                                                                                            killed patient-derived
                                                                                                                                 MGTA-117               100
               0.01-0.05 (Anti-CD117 ADC)                                                50                                                                                 tumor cells and
               0.004-0.08 (Busulfan)                                                                                                                                        extended survival in
                                                                                         25
                                                                                                                                                                            preclinical models2
    ✓   Tool Anti-CD117 ADC enabled                                                       0
        successful transplant of new gene                                                      20    40   60     80   100 120 140 160
                                                                                                Single
        marked stem cells in primates1                                                          Dose
                                                                                                               Days

31 (NASDAQ:MGTA)   Sources: Pre-Clinical Data: 1Uchida et al. Biol Blood Marrow Transplant. 26 (3): S6;
                   2Pearse et al. Biol Blood Marrow Transplant. 2020, 26 (3): S35-S36
MGTA-117 Competitive Positioning

                                                  MGTA-117        JSP191      Iomab-B        GS-0174
                                                  (Magenta)      (Jasper)    (Actinium)      (Gilead)
     Target                                         CD117         CD117         CD45          CD117
                                                 Antibody-Drug
     Modality                                     Conjugate
                                                                 Antibody   Radioconjugate   Antibody

     Stage of Development                            IND          Ph 1/2        Ph 3           Ph 1

     Combined with RIC or Nonmyeloablative
     Conditioning (NMAC)                              ✓            ✓             ✓              ?
     Engineered for Rapid Clearance,
     Enabling Shorter Time to Transplant              ✓             ×             ×             ×
     Potent Depletion (Conjugated Payload)            ✓             ×            ✓              ×
     Selective Targeting of Stem Cells                ✓            ✓              ×            ✓
     Practical: No Requirement for Specialized
     Nuclear Medicine Infrastructure                  ✓            ✓              ×            ✓

32 (NASDAQ:MGTA)
MGTA-117 Program Status and
                        Next Steps for First-in-Human Clinical Trial in AML & MDS

                    Program Status                                  Next Steps

               •   Investigational New Drug (IND) application   •   Expect to open the Phase 1/2 clinical trial in
                   for MGTA-117 is active with the U.S. Food        Q4 2021 to evaluate MGTA-117 antibody-
                   and Drug Administration (FDA)                    drug conjugate (ADC) targeted conditioning
                                                                    program.

                                                                •   Planning gene therapy applications with
                                                                    partners

33 (NASDAQ:MGTA)
The MGTA-117 Opportunity in Allogeneic Blood Cancers:
                   Improve Survival Outcomes and Expand Use of Stem Cell Transplant

                              annual stem cell
   11,300                     transplants
                                                                                                                           MGTA-117

   for AML and MDS in major
   global markets1

                                                                                                     Large Existing Market Opportunity:
                           of patients                                                                   • Leukemias and myelodysplastic syndromes are
   >50%                    with durable
                           cure*                  40%                of eligible
                                                                     patients                              common indications for stem cell transplant

   following stem cell transplant                 do not receive stem cell                           Significant Limitations of Current
   with myeloablative                             transplant, in part due to                         Conditioning Options:
   conditioning2                                  toxic conditioning3                                    • Tradeoff between efficacy of MAC and safety of
                                                                                                           RIC that impact outcomes for all patients

                                                                                                     Opportunity to Expand Use Across Eligible
                                                                                                     Patients:
   ~50% relapse                                   ~20% mortality                                         • Patient risk/benefit analysis causes 40% of
                                                                                                           eligible patients to choose not to receive stem
   within 18 months for patients                  associated with high-
                                                                                                           cell transplant3
   receiving reduced intensity                    intensity myeloablative
   conditioning2                                  conditioning regimens2
                *Durable cure defined as relapse-free survival at 5 years post-transplant; Major Global Markets: U.S., Germany, France, U.K., Italy, Spain, and Japan
34 (NASDAQ:MGTA)Sources: 1CIBMTR, EBMT, and APBMT Transplant Registry Data (2018); 2Scott, BL. Biol Blood Marrow Transplant. 2020, 26 (3): S11;
                3Magenta Market Research, Data on File (2020)
The MGTA-117 Opportunity in HSC Gene Therapy:
           Eliminate Toxic Busulfan Conditioning and Expand Patients Who Can Benefit
                                              projected annual

   5,000 – 10,000                             HSC gene therapy
                                              patients
                                                                                                                           MGTA-117
   across indications by ~2030; in SCD, initial opportunity to treat
   ~25k prevalent patients with potential expansion up to ~150k1
                                                                                               All HSC Gene Therapies Require Patient
                                                                                               Conditioning:
                           of patients
                                                                                                  • Conditioning clears space in bone marrow to make
    >90%                   with
                           functional
                           cure*
                                                 5-10%                      of
                                                                            patients
                                                                                                    room for the new gene modified stem cells

   following HSC gene therapy                    develop secondary                             Serious Long-term Consequences of Busulfan
   in clinical studies2                          malignancies after                            Conditioning:
                                                 chemo conditioning3                              • Significant risk of long-term infertility and secondary
                                                                                                    malignancies
                                                                                                  • Gentler conditioning can expand gene therapy
                                                                                                    opportunity to more patients who can benefit
   >50%                    of
                           children
                                                                                               Expansion Partnerships with Beam and
   experience long-term                          Magenta’s initial clinical                    AVROBIO:
   infertility after busulfan                    partners for MGTA-117 in
                                                                                                  • Partners are responsible for clinical trial costs
   conditioning4                                 gene therapies
                                                                                                  • Magenta can pursue additional partnerships
                 Major Global Markets: U.S., Germany, France, U.K., Italy, Spain and Japan
35 (NASDAQ:MGTA) Sources: 1Analyst reports; 2Thompson et al. Blood. 2020, 136 (Supplement 1): 16-17; 3Shimoni et al. Leukemia. 2013, 27, 829-835;
                 4Brachet et al. J Pediatr Hematol Oncol. 2007, 29 (7): 445-450.
Future

     (NASDAQ:MGTA)
36 (NASDAQ:MGTA)
Magenta’s Research and Discovery Engine

                    TARGETS
             Blood and immune
                  system reset
   CAR-T patient preparation

                                                                           TEAM
                                                DISCOVERY                  Immunology
                                                  ENGINE                   Stem cell biology
                                                                           Antibody & protein
                   MODALITIES
                                                                           engineering
      Antibody-drug conjugates
                     Bispecifics
                        Others

37 (NASDAQ:MGTA)
Conclusion

                           Magenta is the leading immune and blood reset company
                     focused on bringing the potential curative power of stem cell transplant
                                to more patients across multiple disease areas

                   Multiple clinical trials in   Financial position: cash    Focused on execution,
                   2021, with expected           reserves expected to fund   advancing mobilization
                   clinical data across          operations into Q3 2023     and conditioning clinical
                   mobilization program                                      programs and research
                                                                             platform

38 (NASDAQ:MGTA)
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