Magenta Therapeutics : MGTA-145 Ph2 MM Data Review Conference Call Presentation

Magenta Therapeutics Announces Positive Preliminary Results from Phase 2 Clinical Trial of MGTA-145 in Multiple Myeloma

May 12, 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 benefit 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 Annual Report on Form 10-K filed on March 3, 2021, as updated by Magenta's most recent Quarterly Report on Form 10-Q 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.

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Agenda & Introductions

INTRODUCTIONS

PIPELINE OVERVIEW

MGTA-145 MULTIPLE MYELOMA PHASE 2: BACKGROUND, RESULTS AND NEXT STEPS

Q&A SESSION

CLOSING REMARKS

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Jason Gardner	John Davis, MD	Steve Mahoney
CEO, President	Chief Medical Officer	Chief Financial and
and Co-founder	Magenta Therapeutics	Operating Officer
Magenta Therapeutics		Magenta Therapeutics

David Scadden, MD	Steven Devine, MD
Professor of Medicine, Harvard University;	CMO, Be The Match BioTherapies;
Co-founder/Director, Harvard Stem Cell Institute;	CMO, NMDP/Be The Match;
Co-founder/Director, Department of Stem Cell &	Associate Scientific Director, CIBMTR
Regenerative Biology, Harvard University;
Co-founder/SAB Chair, Magenta Therapeutics

The Magenta Pipeline

	Disease Area	Preclinical	IND-Enabling	Phase 1	Phase 2	Clinical Trial	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
	Graft vs. Host Disease
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Magenta 2021: Deliver Clinical Data and Advance Platform

Stem Cell Mobilization

and Collection:

MGTA-145

Targeted Conditioning:

MGTA-117

Conditioning

Research Platform

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Autologous: Final clinical data 2H 2021	Mobilization and
	engraftment;
Allogeneic: Initial data 2H 2021
disease outcomes

Gene Therapy: To initiate 2H 2021		Mobilization
	Assessment of early safety
IND filing June 2021
Initial data Q4 2021 for internal review		and pharmacokinetics data

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