Statement of Changes in Beneficial Ownership (4)

FORM 4 [ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES
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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 ^* MPM BioVentures 2014, L.P.	2. Issuer Name and Ticker or Trading Symbol iTeos Therapeutics, Inc. [ ITOS ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below)
(Last) (First) (Middle) C/O MPM CAPITAL, 450 KENDALL STREET	3. Date of Earliest Transaction (MM/DD/YYYY) 9/14/2021
(Street) CAMBRIDGE, MA 02142 (City) (State) (Zip)	4. 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 Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code (Instr. 8)		4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	9/14/2021		S⁽¹⁾		17938 ⁽²⁾	D	$27.50 ⁽³⁾	3516303	I	See Footnote ⁽⁴⁾
Common Stock	9/14/2021		S⁽¹⁾		3623 ⁽⁵⁾	D	$27.99 ⁽⁶⁾	3512680	I	See Footnote ⁽⁷⁾
Common Stock	9/15/2021		S⁽¹⁾		23113 ⁽⁸⁾	D	$27.79 ⁽⁹⁾	3489567	I	See Footnote ⁽¹⁰⁾
Common Stock	9/15/2021		S⁽¹⁾		991 ⁽¹¹⁾	D	$28.15 ⁽¹²⁾	3488576	I	See Footnote ⁽¹³⁾

*Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)*
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)			11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:
(1)	Transaction effected pursuant to a plan established pursuant to Rule 10b5-1.
(2)	The shares were sold as follows: 10,687 by MPM BioVentures 2014, L.P. ("BV 2014"), 368 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 6,750 by MPM BioVentures 2018, L.P. ("BV 2018") and 133 by MPM Asset Management Investors BV2018 LLC ("AM BV2018"). MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("BV 2014 LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). BV 2014 LLC is the manager of AM BV2014. MPM BioVentures 2018 GP LLC and MPM BioVentures 2018 LLC ("BV 2018 LLC") are the direct and indirect general partners of BV 2018 and BV 2018(B). BV 2018 LLC is the manager of AM BV2018. Messrs. Evnin and Foley are managing directors of BV 2014 LLC and BV 2018 LLC.
(3)	The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $26.91 to $27.90 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
(4)	The shares are held as follows: 1,998,483 by BV 2014, 107,713 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)"), 68,786 by AM BV2014, 1,262,199 by BV 2018, 54,213 by MPM BioVentures 2018(B), L.P. ("BV 2018(B)") and 24,909 by AM BV2018. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein.
(5)	The shares were sold as follows: 2,159 by BV 2014, 74 by AM BV2014, 1,363 by BV 2018 and 27 by AM BV2018.
(6)	The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.92 to $28.055 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
(7)	The shares are held as follows: 1,996,324 by BV 2014, 107,713 by BV 2014(B), 68,712 by AM BV2014, 1,260,836 by BV 2018, 54,213 by BV 2018(B) and 24,882 by AM BV2018. Each of the Reporting Persons disclaims beneficial ownership of the securities herein except to the extent of his or its respective pecuniary interest therein, if any.
(8)	The shares were sold as follows: 13,770 by BV 2014, 474 by AM BV2014, 8,697 by BV 2018 and 172 by AM BV2018.
(9)	The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.12 to $28.11 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
(10)	The shares are held as follows: 1,982,554 by BV 2014, 107,713 by BV 2014(B), 68,238 by AM BV2014, 1,252,139 by BV 2018, 54,213 by BV 2018(B) and 24,710 by AM BV2018. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein.
(11)	The shares were sold as follows: 591 by BV 2014, 20 by AM BV2014, 373 by BV 2018 and 7 by AM BV2018.
(12)	The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.13 to $28.19 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
(13)	The shares are held as follows: 1,981,963 by BV 2014, 107,713 by BV 2014(B), 68,218 by AM BV2014, 1,251,766 by BV 2018, 54,213 by BV 2018(B) and 24,703 by AM BV2018. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein.

Remarks:
See Form 4 for MPM BioVentures 2018, L.P for additional members of this joint filing.

Reporting Owners
Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
MPM BioVentures 2014, L.P. C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA 02142		X
EVNIN LUKE C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA 02142		X
Foley Todd C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA 02142		X
MPM BioVentures 2014 (B), L.P. C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA 02142		X
MPM Asset Management Investors BV2014 LLC C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA 02142		X
MPM BioVentures 2014 LLC C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA 02142		X
MPM BioVentures 2014 GP LLC C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA 02142		X
MPM BIOVENTURES 2018 (B), L.P. C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA 02142		X
MPM ASSET MANAGEMENT INVESTORS BV2018 LLC C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE, MA 02142		X

Signatures
/s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC, the general partner of MPM BioVentures 2014, L.P.		9/16/2021
^**Signature of Reporting Person		Date
/s/ Luke Evnin		9/16/2021
^**Signature of Reporting Person		Date
/s/ Todd Foley		9/16/2021
^**Signature of Reporting Person		Date
/s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC, the general partner of MPM BioVentures 2014 (B), L.P.		9/16/2021
^**Signature of Reporting Person		Date
/s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the manager of MPM Asset Management Investors BV2014 LLC		9/16/2021
^**Signature of Reporting Person		Date
/s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC		9/16/2021
^**Signature of Reporting Person		Date
/s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC		9/16/2021
^**Signature of Reporting Person		Date
/s/ Ansbert Gadicke, managing director of MPM BioVentures 2018 LLC, the managing member of MPM BioVentures 2018 GP LLC, the general partner of MPM BioVentures 2018 (B), L.P.		9/16/2021
^**Signature of Reporting Person		Date
/s/ Ansbert Gadicke, managing director of MPM BioVentures 2018 LLC, the manager of MPM Asset Management Investors BV2018 LLC		9/16/2021
^**Signature of Reporting Person		Date