X0206 3 2019-07-24 0 0001447362 CASTLE BIOSCIENCES INC CSTL 0001623049 Aspinall Mara G. C/O CASTLE BIOSCIENCES, INC. 820 S. FRIENDSWOOD DRIVE, SUITE 201 FRIENDSWOOD TX 77546 1 0 0 0 Common Stock 23630 D Stock option (right to buy) 1.92 2026-01-17 Common Stock 1118 D Stock option (right to buy) 16.00 2029-07-23 Common Stock 30895 D Series F Preferred Stock Common Stock 14093 D 25% of the shares vested on January 18, 2017, and the remaining shares vest in 36 equal monthly installments thereafter. 25% of the shares shall vest on August 1, 2020, and the remaining shares vest in 36 equal monthly installments thereafter. 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. /s/ Greg Acosta, Attorney-in-fact 2019-07-24