Sec Form 3 Filing - Spiess Bernhard E. @ CASTLE BIOSCIENCES INC - 2019-07-24

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 Spiess Bernhard E. 2. Issuer Name and Ticker or Trading Symbol CASTLE BIOSCIENCES INC [ CSTL] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Operating Officer (Last) (First) (Middle) C/O CASTLE BIOSCIENCES, INC., 820 S. FRIENDSWOOD DRIVE, STE. 201 3. Date of Earliest Transaction (MM/DD/YY) 07/24/2019 (Street) FRIENDSWOOD, TX77546 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 117,081 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) $ 1.92 ( 1 ) 05/23/2026 Common Stock 41,222 D Stock option (right to buy) $ 1.92 ( 2 ) 05/23/2026 Common Stock 14,878 D Stock option (right to buy) $ 2.39 ( 2 ) 05/09/2028 Common Stock 8,716 D Stock option (right to buy) $ 3.38 ( 3 ) 03/12/2029 Common Stock 24,610 D Series F Preferred Stock ( 4 ) ( 4 ) ( 4 ) Common Stock 5,637 D Convertible Promissory Note ( 5 ) ( 5 ) ( 5 ) Common Stock $ 20,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Spiess Bernhard E. C/O CASTLE BIOSCIENCES, INC. 820 S. FRIENDSWOOD DRIVE, STE. 201 FRIENDSWOOD, TX77546 Chief Operating Officer Signatures /s/ Greg Acosta, Attorney-in-fact 07/24/2019 Signature of Reporting Person Date

Explanation of Responses:

( 1 )25% of the 154,714 shares originally subject to the option (after giving effect to the 1 for 1.219 reverse stock split) vested on May 2, 2017, and the remaining shares vest in 36 equal monthly installments thereafter. ( 2 )25% of the 12,305 shares originally subject to the option (after giving effect to the 1 for 1.219 reverse stock split) vested on May 10, 2019, and the remaining shares vest in 36 equal monthly installments thereafter. ( 3 )25% of the shares shall vest on March 13, 2020, and the remaining shares shall vest in 36 equal monthly installments thereafter. ( 4 )All outstanding shares of Preferred Stock will automatically convert into shares of Common Stock immediately upon the closing of the Issuer's initial public offering (the "IPO"), for no additional consideration at a rate of 1 share of Common Stock for each 1.219 shares of Preferred Stock, based on the conversion price currently in effect. The Preferred Stock has no expiration date. ( 5 )The principal amount of the Convertible Promissory Note held by the designated Reporting Person is $20,000.00. Upon closing of the IPO, all unpaid principal and accrued interest outstanding on the Convertible Promissory Note (the "Conversion Amount") will automatically convert into the number of shares of Common Stock that is equal to the Conversion Amount as of the closing date divided by 80% of the IPO price per share.

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 4(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).

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