Initial Statement of Beneficial Ownership (3)

FORM 3	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0104 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * Foresite Capital Management V, LLC	2. Date of Event Requiring Statement (MM/DD/YYYY) 6/9/2022	3. Issuer Name and Ticker or Trading Symbol Theseus Pharmaceuticals, Inc. [THRX]
(Last)        (First)        (Middle) 900 LARKSPUR LANDING CIRCLE, SUITE 150	4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director                          ___X___ 10% Owner _____ Officer (give title below)        _____ Other (specify below)
(Street) LARKSPUR, CA 94939       (City)              (State)              (Zip)	5. If Amendment, Date Original Filed(MM/DD/YYYY)	6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	3335346	I	See Footnote (1)
Common Stock	959275	I	See Footnote (2)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 4)	2. Date Exercisable and Expiration Date (MM/DD/YYYY)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:
(1)	The shares are owned directly by Foresite Capital Fund V, L.P. ("Fund V"). Foresite Capital Management V, LLC ("FCM V") is the general partner of Fund V and may be deemed to have sole voting and dispositive power over these shares. James B. Tananbaum ("Dr. Tananbaum") is the sole managing member of FCM V and may be deemed to have sole voting and dispositive power over these shares. Each Reporting Person disclaims the existence of a "group." Each of FCM V and Dr. Tananbaum disclaims beneficial ownership of these shares except to the extent of any pecuniary interest therein, and the filing of this report is not an admission that FCM V or Dr. Tananbaum is the beneficial owner of these shares for purposes of Section 16 or any other purpose.
(2)	The shares are owned directly by Foresite Capital Opportunity Fund V, L.P. ("Opportunity Fund V"). Foresite Capital Opportunity Management V, LLC ("FCOM V") is the general partner of Opportunity Fund V and may be deemed to have sole voting and dispositive power over these shares. Dr. Tananbaum is the sole managing member of FCOM V and may be deemed to have sole voting and dispositive power over these shares. Each Reporting Person disclaims the existence of a "group." Each of FCOM V and Dr. Tananbaum disclaims beneficial ownership of these shares except to the extent of any pecuniary interest therein, and the filing of this report is not an admission that FCOM V or Dr. Tananbaum is the beneficial owner of these shares for purposes of Section 16 or any other purpose.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Foresite Capital Management V, LLC 900 LARKSPUR LANDING CIRCLE SUITE 150 LARKSPUR, CA 94939		X
Foresite Capital Fund V, L.P. 900 LARKSPUR LANDING CIRCLE SUITE 150 LARKSPUR, CA 94939		X
Foresite Capital Opportunity Fund V, L.P. 900 LARKSPUR LANDING CIRCLE SUITE 150 LARKSPUR, CA 94939		X
Foresite Capital Opportunity Management V, LLC 900 LARKSPUR LANDING CIRCLE SUITE 150 LARKSPUR, CA 94939		X
Tananbaum James B. 900 LARKSPUR LANDING CIRCLE SUITE 150 LARKSPUR, CA 94939		X

Signatures
FORESITE CAPITAL MANAGEMENT V, LLC, By: /s/ James B. Tananbaum, Managing Member		6/13/2022
**Signature of Reporting Person		Date
FORESITE CAPITAL FUND V, L.P., By: Foresite Capital Management V, LLC, Its: General Partner, By: /s/ James B. Tananbaum, Managing Member		6/13/2022
**Signature of Reporting Person		Date
FORESITE CAPITAL OPPORTUNITY FUND V, L.P., By: Foresite Capital Opportunity Management V, LLC, Its: General Partner, By: /s/ James B. Tananbaum, Managing Member		6/13/2022
**Signature of Reporting Person		Date
FORESITE CAPITAL OPPORTUNITY MANAGEMENT V, LLC, By: /s/ James B. Tananbaum, Managing Member		6/13/2022
**Signature of Reporting Person		Date
JAMES B. TANANBAUM /s/ James B. Tananbaum		6/13/2022
**Signature of Reporting Person		Date

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
*	If the form is filed by more than one reporting person, see Instruction 5(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note:	File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.