144 0001239501 XXXXXXXX LIVE 0001447362 Castle Biosciences, Inc. 001-38984 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 1-866-788-9007 Derek Maetzold Officer Common Goldman Sachs & Co. LLC 200 West Street New York NY 10282 16932 344566.2 28872315 06/27/2025 NASD Common 10/29/2007 Acquired as gift Derek Maetzold Y 10/29/2007 6051 10/29/2007 None Common 10/29/2007 Acquired as gift Derek Maetzold Y 10/29/2007 5193 10/29/2007 None Common 08/09/2024 Acquired as compensation -- Performance Awards Issuer N 3708 08/09/2024 Compensation Common 10/29/2007 Acquired as a gift Derek Maetzold Y 10/29/2007 495 10/29/2007 None Common 10/29/2007 Acquired as a gift Derek Maetzold Y 10/29/2007 495 10/29/2007 None Common 10/29/2007 Acquired as a gift Derek Maetzold Y 10/29/2007 495 10/29/2007 None Common 10/29/2007 Acquired as a gift Derek Maetzold Y 10/29/2007 495 10/29/2007 None N The Maetzold Descendants 2020 Trust dtd 12/4/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/09/2025 1669 33746.01 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/09/2025 137 2770.04 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/09/2025 137 2770.04 Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/09/2025 1023 20684.34 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/09/2025 1432 28954.04 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/09/2025 137 2770.04 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/09/2025 135 2729.61 The Maetzold Descendants 2020 Trust dtd 12/4/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/08/2025 348 6970.44 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/08/2025 28 560.84 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/08/2025 28 560.84 Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/08/2025 213 4266.39 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/08/2025 299 5988.97 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/08/2025 28 560.84 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/08/2025 30 600.9 The Maetzold Descendants 2020 Trust dtd 12/4/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/21/2025 2017 43402.21 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/21/2025 165 3550.5 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/21/2025 165 3550.5 Derek Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/21/2025 1236 26596.5 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/21/2025 1731 37248 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/21/2025 165 3550.5 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 505 S. Friendswood Drive Suite 401 Friendswood TX 77546 Common 04/21/2025 165 3550.5 Total number of shares to be sold includes: 3,708 shares by Derek Maetzold, 5,193 shares by DM 2020 Irrev Tr, 6051 shares by Maetzold Descendants 2020 Tr, 495 shares by Hannah Maetzold Irrev. Trust, 495 shares by Peter Maetzold Irrev. Trust, 495 shares by Emily Maetzold Irrev. Trust, 495 shares by John Maetzold Irrev. Trust. The sales of shares set forth herein are made in connection with a selling plan dated 11/11/2024 that is intended to comply with Rule 10b5-1(c). 06/27/2025 11/11/2024 Goldman Sachs & Co. LLC on behalf of Derek Maetzold