X0306 4 2019-07-29 0 0001447362 CASTLE BIOSCIENCES INC CSTL 0001024008 KABAKOFF DAVID S C/O CASTLE BIOSCIENCES, INC. 820 S. FRIENDSWOOD DRIVE, SUITE 201 FRIENDSWOOD TX 77546 1 0 1 0 Common Stock 2019-07-29 4 C 0 1676061 A 1676061 I By L.P. Common Stock 2019-07-29 4 C 0 83453 12.80 A 1759514 I By L.P. Common Stock 2019-07-29 4 X 0 11572 0.02 A 1771086 I By L.P. Common Stock 2019-07-29 4 S 0 9 16.00 D 1771077 I By L.P. Common Stock 2019-07-29 4 P 0 62500 16.00 A 1833577 I By L.P. Series A Preferred Stock 2019-07-29 4 C 0 19524 D Common Stock 16015 0 I By L.P. Series E-2 Preferred Stock 2019-07-29 4 C 0 436910 D Common Stock 358416 0 I By L.P. Series E-3 Preferred Stock 2019-07-29 4 C 0 388669 D Common Stock 318842 0 I By L.P. Series F Preferred Stock 2019-07-29 4 C 0 1198016 D Common Stock 982785 0 I By L.P. Convertible Promissory Note 12.80 2019-07-29 4 C 0 1027882.00 D Common Stock 83453 0 I By L.P. Warrant to purchase Series F Preferred Stock 0.02 2019-07-29 4 X 0 14107 0.00 D 2019-07-29 Common Stock 11572 0 I By L.P. The shares of Common Stock issued upon conversion of the Preferred Stock were calculated by first aggregating all series of Preferred Stock held by the Reporting Person, in accordance with the terms of the Company's then-effective Certificate of Incorporation. Every 1.219 outstanding shares of Preferred Stock automatically converted into 1 share of Common Stock immediately prior to the closing of the Issuer's initial public offering (the "IPO"), for no additional consideration, with cash paid for any fractional shares. The Preferred Stock had no expiration date. Held by Sofinnova HealthQuest Partners, L.P., or HealthQuest Partners. HealthQuest Venture Management, L.L.C., or HealthQuest Management, is the managing member of HealthQuest Partners. David Kabakoff, Ph.D., the Reporting Person, is a partner of HealthQuest Management. Garheng Kong is the managing member of HealthQuest Management and has sole voting and investment power over the shares held by HealthQuest Partners. Each of HealthQuest Management, Mr. Kong and Dr. Kabakoff disclaims beneficial ownership over all shares held by HealthQuest Partners except to the extent of any pecuniary interest therein. The principal amount of the Convertible Promissory Note held by HealthQuest Partners was $1,027,882. Upon closing of the IPO, all unpaid principal and accrued interest outstanding on the Convertible Promissory Note (the "Conversion Amount") automatically converted into the number of shares of Common Stock equal to the Conversion Amount as of the date immediately prior to the closing date divided by 80% of the IPO price per share of $16.00 per share. On July 29, 2019, the reporting person exercised a warrant to purchase 11,572 shares of the Issuer's common stock for approximately $0.02 per share. The reporting person paid the exercise price on a cashless basis, resulting in the Issuer's withholding of 9 of the warrant shares to pay the exercise price and issuing to the reporting person the remaining 11,563 shares. Represents a purchase from the underwriters in the Issuer's IPO. Immediately prior to the closing of the IPO, the warrant became exercisable for 11,572 shares of Common Stock. Immediately exercisable. /s/ Greg Acosta, Attorney-in-fact 2019-07-31