Rock Springs Capital Management Form 3 Initial statement of insider ownership

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person^*

Rock Springs Capital Management LP

(Last) (First) (Middle)

650 SOUTH EXETER ST., SUITE 1070

(Street)

BALTIMORE MD 21202

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
10/06/2021

3. Issuer Name and Ticker or Trading Symbol
Theseus Pharmaceuticals, Inc. [ THRX ]

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

Director	X	10% Owner
Officer (give title below)		Other (specify below)

5. If Amendment, Date of Original Filed (Month/Day/Year)

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)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: 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
Series B Convertible Preferred Stock	(1)	(1)	Common Stock	349,320	(1)	I	See Footnote(2)
Series B Convertible Preferred Stock	(1)	(1)	Common Stock	87,329	(1)	I	See Footnote(3)

1. Name and Address of Reporting Person^*

Rock Springs Capital Management LP

(Last) (First) (Middle)

650 SOUTH EXETER ST., SUITE 1070

(Street)

BALTIMORE MD 21202

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Rock Springs Capital Master Fund LP

(Last) (First) (Middle)

C/O WALKERS CORPORATE LIMITED,

AYMAN CO CENTER 27 HOSPITAL ROAD

(Street)

GEORAGE TOWN E9 KY-1-9008

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Rock Springs Capital LLC

(Last) (First) (Middle)

650 SOUTH EXETER ST., SUITE 1070

(Street)

BALTIMORE MD 2102

(City) (State) (Zip)

Explanation of Responses:

1. The reported security is convertible into the issuer's Common Stock on a one-for-one basis at any time at the holder's election and shall automatically convert into Common Stock immediately prior to the closing of the issuer's initial public offering without payment of further consideration. The shares have no expiration date.

2. The securities reported herein are held of record by Rock Springs Capital Master Fund LP ("Master Fund"). Rock Springs Capital LLC ("RSC") is the general partner of Rock Springs Capital Management LP ("RSCM") which is the investment manager to Master Fund. RSC and RSCM may therefore be deemed to have or share beneficial ownership of the shares held directly by Master Fund.

3. The securities reported herein are held of record by Four Pines Master Fund LP ("Four Pines"). RSC is the general partner of RSCM which is the investment manager to Four Pines. RSC and RSCM may therefore be deemed to have or share beneficial ownership of the shares held directly by Four Pines.

Remarks:

	By: /s/ Mark Bussard, Authorized Signatory, Rock Springs Capital Management LP	10/06/2021
	By: /s/ Mark Bussard, Authorized Signatory, Rock Springs Capital Master Fund LP	10/06/2021
	By: /s/ Mark Bussard, Authorized Signatory, Rock Springs Capital LLC	10/06/2021
	** 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).
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