Sec Form 3 Filing - Kuriakose Emil @ Calithera Biosciences, Inc. - 2021-11-05

FORM 3 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 Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Kuriakose Emil 2. Issuer Name and Ticker or Trading Symbol Calithera Biosciences, Inc. [ CALA] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) CHIEF MEDICAL OFFICER (Last) (First) (Middle) C/O CALITHERA BIOSCIENCES, INC., 343 OYSTER POINT BLVD. #200 3. Date of Earliest Transaction (MM/DD/YY) 11/05/2021 (Street) SOUTH SAN FRANCISCO, CA94080 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction 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) Code V Amount (A) or (D) Price Common Stock 60,467 ( 1 ) ( 2 ) ( 3 ) D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares STOCK OPTION (RIGHT TO BUY) $ 15.75 ( 4 ) 09/28/2027 COMMON STOCK 38,000 D STOCK OPTION (RIGHT TO BUY) $ 5.61 ( 5 ) 10/08/2028 COMMON STOCK 12,667 D STOCK OPTION (RIGHT TO BUY) $ 4.64 ( 6 ) 01/09/2029 COMMON STOCK 21,000 D STOCK OPTION (RIGHT TO BUY) $ 7.41 ( 7 ) 01/16/2030 COMMON STOCK 40,000 D STOCK OPTION (RIGHT TO BUY) $ 2.98 ( 8 ) 01/19/2031 COMMON STOCK 33,375 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Kuriakose Emil C/O CALITHERA BIOSCIENCES, INC. 343 OYSTER POINT BLVD. #200 SOUTH SAN FRANCISCO, CA94080 CHIEF MEDICAL OFFICER Signatures /s/ Emil Kuriakose, Name: Emil Kuriakose 11/09/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Includes 14,089 shares acquired at various dates pursuant to the Company's 2014 Employee Stock Purchase Plan. ( 2 )Includes 26,961 shares acquired upon the vesting of a restricted stock unit award, net of shares sold to satisfy tax obligations, arising out of the vesting of previously granted restricted stock units. ( 3 )Includes an aggregate of 19,417 shares of common stock to be acquired upon the vesting of Restricted Stock Unit awards granted to the Reporting Person. The Restricted Stock Units shall vest as follows: a) 7,417 restricted stock units shall vest according to the following schedule: one-fourth (1/4th) of the shares subject to the Restricted Stock Unit award will vest each year after January 20, 2021 until the Restricted Stock Units are fully vested, b) 12,000 restricted stock units shall fully vest on January 3, 2022. The Restricted Stock Units shall be subject to accelerated vesting as set forth in the Reporting Person's employment agreement with the Company. ( 4 )One-fourth (1/4th) of the Option vests one year after September 29, 2017; the balance of the Option vests in a series of thirty-six (36) successive equal monthly installments thereafter. The Option shall be subject to accelerated vesting as set forth in the Reporting Person's employment agreement with the Company. ( 5 )One-fourth (1/4th) of the Option vests one year after October 9, 2018; the balance of the Option vests in a series of thirty-six (36) successive equal monthly installments thereafter. The Option shall be subject to accelerated vesting as set forth in the Reporting Person's employment agreement with the Company. ( 6 )One-fourth (1/4th) of the Option vests one year after January 10, 2019; the balance of the Option vests in a series of thirty-six (36) successive equal monthly installments thereafter. The Option shall be subject to accelerated vesting as set forth in the Reporting Person's employment agreement with the Company. ( 7 )One-fourth (1/4th) of the Option vests one year after January 17, 2020; the balance of the Option vests in a series of thirty-six (36) successive equal monthly installments thereafter. The Option shall be subject to accelerated vesting as set forth in the Reporting Person's employment agreement with the Company. ( 8 )One-fourth (1/4th) of the Option vests one year after January 20, 2021; the balance of the Option vests in a series of thirty-six (36) successive equal monthly installments thereafter. The Option shall be subject to accelerated vesting as set forth in the Reporting Person's employment agreement with the Company.

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* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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