144 0001239501 XXXXXXXX LIVE 0001447362 Castle Biosciences, Inc. 001-38984 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 1-866-788-9007 Derek Maetzold Officer Common Goldman Sachs & Co. LLC 200 West Street New York NY 10282 23844 589185.24 30329952 07/01/2026 NASD Common 10/29/2007 Acquired as gift Derek Maetzold Y 10/29/2007 4071 10/29/2007 None Common 10/29/2007 Acquired as gift Derek Maetzold Y 10/29/2007 3459 10/29/2007 None Common 10/29/2007 Acquired as gift Derek Maetzold Y 10/29/2007 834 10/29/2007 None Common 10/29/2007 Acquired as gift Derek Maetzold Y 10/29/2007 834 10/29/2007 None Common 10/29/2007 Acquired as gift Derek Maetzold Y 10/29/2007 834 10/29/2007 None Common 10/29/2007 Acquired as gift Derek Maetzold Y 10/29/2007 834 10/29/2007 None Common 05/10/2018 Acquired as compensation -- Stock Options Issuer N 12978 05/10/2018 Compensation -- Cashless exercise / same-day sale N The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/06/2026 278 6941.34 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/06/2026 278 6941.34 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/06/2026 278 6941.34 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/06/2026 1153 28789.12 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/06/2026 6214 155156.64 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/06/2026 1357 33882.78 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/06/2026 278 6941.34 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/21/2026 1357 33975.31 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/21/2026 278 6960.3 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/21/2026 1153 28867.75 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/21/2026 278 6960.3 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/21/2026 550 13770.39 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/21/2026 278 6960.3 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 04/21/2026 278 6960.3 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/07/2026 278 6142.06 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/07/2026 6214 137290.52 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/07/2026 278 6142.06 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/07/2026 1153 25474.08 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/07/2026 278 6142.06 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/07/2026 1357 29981.21 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/07/2026 278 6142.06 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/20/2026 322 6421.25 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/20/2026 66 1316.16 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/20/2026 66 1316.16 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/20/2026 273 5444.1 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/20/2026 66 1316.16 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/20/2026 66 1316.16 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/20/2026 130 2592.43 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/21/2026 212 4268.74 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/21/2026 212 4268.74 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/21/2026 212 4268.74 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/21/2026 1035 20840.32 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/21/2026 880 17719.31 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/21/2026 420 8456.94 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 05/21/2026 212 4268.74 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/01/2026 278 5781.56 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/01/2026 278 5781.56 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/01/2026 278 5781.56 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/01/2026 1153 23978.9 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/01/2026 1357 28221.48 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/01/2026 278 5781.56 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/01/2026 6214 129232.37 The Maetzold 2018 Remainder Trust f/b/o Peter Douglas Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 278 5726.07 The Maetzold 2018 Remainder Trust f/b/o John Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 278 5726.07 The Maetzold 2018 Remainder Trust f/b/o Emily Carol Kirk 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 278 5726.07 The Maetzold 2018 Remainder Trust f/b/o Hannah Elizabeth Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 278 5726.07 Derek Maetzold 2020 Irrevocable Trust dtd 12/04/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 1153 23748.76 The Maetzold Descendants 2020 Trust dtd 12/4/2020 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 1357 27950.63 Derek Maetzold 1500 W. Parkwood Ave Suite 400 Friendswood TX 77546 Common 06/15/2026 550 11328.55 The sales of shares set forth herein are made in connection with a selling plan dated 12/3/2025 that is intended to comply with Rule 10b5-1(c). Total number of shares to be sold includes: 12,978 shares by Derek Maetzold, 3,459 shares by DM 2020 Irrev Tr, 4,071 shares by Maetzold Descendants 2020 Tr, 834 shares by Hannah Maetzold Irrev. Trust, 834 shares by Peter Maetzold Irrev. Trust, 834 shares by Emily Maetzold Irrev. Trust, 834 shares by John Maetzold Irrev. Trust. 07/01/2026 12/03/2025 Goldman Sachs & Co. LLC on behalf of Derek Maetzold