Constellation Pharmaceuticals : ASH 2020 MANIFEST Data- Investor Event Presentation

CPI-0610:

Update of Preliminary Data fromMANIFEST

Analyst/Investor Meeting on ASH 2020

Stellar Science, Breakthrough Medicine

December 7, 2020

Forward-Looking Statements

This presentation contains forward-looking statements within the meaning of The Private Securities Litigation Reform Act of

1995 that involve substantial risks and uncertainties, including statements regarding the implications of preliminary or interim clinical data, the Company's plans, strategies and prospects for its business and statements regarding the development status of the Company's

product candidates. The words "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "plan," "potential," "predict," "project," "should," "target," "will," "would" and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Any forward-looking statements are based on management's current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. These risks and uncertainties include, but are not limited to, risks associated with the Company's ability to: obtain and maintain necessary approvals from the FDA and other regulatory authorities; continue to advance its product candidates in clinical trials; whether preliminary or interim data from a clinical trial will be predictive of the final results of the trial; replicate in later clinical trials positive results found in preclinical studies and early-stage clinical trials of CPI-0610 and CPI- 0209; advance the development of its product candidates under the timelines it anticipates, or at all, in current and future clinical trials; obtain, maintain, or protect intellectual property rights related to its product candidates; manage expenses; raise the substantial additional capital needed to achieve its business objectives; the COVID-19 pandemic and general economic and market conditions. CPI-0610 and CPI-

0209 are investigational therapies and have not been approved by the FDA (or any other regulatory authority). For a discussion of other risks and uncertainties, any of which could cause the Company's actual results to differ from those contained in the forward-looking statements, see the "Risk Factors" section, as well as discussions of potential risks, uncertainties, and other important factors, in the Company's

most recent filings with the Securities and Exchange Commission, including the Company's Quarterly Report on Form 10-Q for the quarter ended September 30, 2020. In addition, the forward-looking statements included in this presentation represent the Company's views as of the date hereof and should not be relied upon as representing the Company's views as of any date subsequent to the date hereof. The Company anticipates that subsequent events and developments will cause the Company's views to change. However, while the Company may elect to update these forward-looking statements at some point in the future, the Company specifically disclaims any obligation to do so.

2

MANIFEST at ASH 2020

Constellation Pharmaceuticals Analyst/Investor Meeting

Jigar Raythatha	Jeffery Humphrey, M.D.	Katarina Luptakova, M.D.	Patrick Trojer, Ph.D.
President and CEO	Chief Medical Officer	VP, Clinical Development	Chief Scientific Officer

John Mascarenhas, M.D.	Srdan Verstovsek, M.D.
Associate Professor of Medicine	Professor of Medicine
Icahn School of Medicine at Mount Sinai - New York	University of Texas MD Anderson Cancer Center

3

Agenda

Topic	Presenter
Company Profile	Jigar Raythatha
Unmet Need in Myelofibrosis (MF)
Highlights of CPI-0610 ASH data	Jeff Humphrey
MANIFEST Clinical Data	Katarina Luptakova
MANIFEST Translational Data	Patrick Trojer
KOL Panel	Moderator: Jigar Raythatha
KOLs: John Mascarenhas
	Srdan Verstovsek

4