Constellation Pharmaceuticals : Corporate Presentation—June 4, 2021

Forward-Looking Statements

This presentation contains forward-looking statements within the meaning of Private Securities Litigation Reform Act of 1995 that involve substantial risks and uncertainties, including statements regarding the Company's plans, strategies and prospects for its business and statements regarding the development status of the Company's product candidates, the timing of availability of clinical trial data and the Company's ability to fund its operations until the second half of 2022. 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; the Company's ability to 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; replication in later clinical trials positive results found in preclinical studies and early-stage clinical trials of CPI-0610,CPI-1205 and CPI-0209; the Company's ability to advance the development of its product candidates under the timelines it anticipates, or at all, in current and future clinical trials; the Company's ability to obtain, maintain, or protect intellectual property rights related to its product candidates; manage expenses; the Company's ability to raise the substantial additional capital needed to achieve its business objectives; the COVID-19 pandemic and general economic and market conditions; and whether the previously announced acquisition of the Company by MorphoSys AG will be consummated on a timely basis. CPI-0610,CPI-1205 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. 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.

1

CONFIDENTIAL

Addressing the Breadth of EZH2 Biology

Polycomb Repressive Complex 2 (PRC2)

Broad Implications

in Cancer

Activating mutations

CPI-0209 vs.

1st Gen EZH2i

EZH2

EZH2

PRC2

Oncogenicdriver synergy

CPI-0209

Increased potency

H3K27me3

OFF

EZH2 trimethylates histone H3 at lysine 27 and suppresses transcription

EZH2i = enhancer of zeste homolog 2 (EZH2) inhibitor

Synthetic lethal relationships

Drug resistance

Tumor immunity

Long residence time

No evidence of reduced exposure due to induced

metabolism

Extracts full potential of

EZH2 inhibition

2

CONFIDENTIAL

Improved Target Engagement Results in High Levels of Single Agent in vivo Efficacy Across a Range of Tumors

Target Engagement in vivo - H3K27me3

HT1376 ARID1A mutant Bladder Cancer Xenograft model

(%)	160							Vehicle (PO QD)
							CPI-0209 75 mg/kg PO QD from D1-13
RelativeRatio H3K27me3/H3	140
20
	120
	100
	80
	60
	40
of	0
D13	(0)				D14	(1)			D15	(2)			D16	(3)							D19	(6)				D24	(11)
	Days post treatment start (days post dose suspension)

			Lymphoma
)	2500		Vehicle (PO,QD)
3			CPI-0209 (10 mg/kg, PO,QD)
(mm	2000
volume	1500
1000
Tumor	500				109% TGI
0
	0	5	10	15	20	25	30

Time (day)

			Bladder
)	3000	Vehicle (PO,QD)
3		CPI-0209 (75 mg/kg, PO,QD)
(mm	2500
volume	2000
1500
Tumor	1000
500					>100%TGI
	0
	0	10	20	30	40	50	60

Time (day)

			Prostate
)	2000	Vehicle (PO,QD)
3		CPI-0209 (75 mpk, PO,QD)
(mm	1500
volume	1000					76% TGI
Tumor	500
0
	0	10	20	30	40	50	60

Time (day)

		Endometrial
(mm3)	6000	Vehicle (PO, QD)
	CPI-0209 (PO, QD)
Volume	4000
2000
Tumor
0		>100% TGI
	0	10	20	30

Time (day)

3

CONFIDENTIAL

No Evidence of Decreased Exposure at C2D1

Exposure and Cmax of CPI-0209 Increases with Dose

4

CONFIDENTIAL

Comprehensive Target Engagement Observed Clinically

Target Engagement in humans - H3K27me3

Phase 1 Dose Escalation Portion

Cycle 1 day 8 (C1D8) compared to baseline

change H3K27me3/total H3	compared to baseline
%

0 -20-40-60

-80

-100-120

	mg mg		mg	mg	mg	mg mg
50	100		5		5	275	375
. .	225
		137		187

Dose

5

CONFIDENTIAL