# EDGAR Filing Document

**Accession Number:** 0001447362
**File Stem:** 0001628280-25-048270
**Filing Date:** 2025-11
**Character Count:** 31512
**Document Hash:** 9f45e759a9e68d1807b6b220c8f2bb30
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001628280-25-048270.hdr.sgml**: 20251103

**ACCESSION NUMBER**: 0001628280-25-048270

**CONFORMED SUBMISSION TYPE**: S-8

**PUBLIC DOCUMENT COUNT**: 15

**FILED AS OF DATE**: 20251103

**DATE AS OF CHANGE**: 20251103

**EFFECTIVENESS DATE**: 20251103

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** CASTLE BIOSCIENCES INC
- **CENTRAL INDEX KEY:** 0001447362
- **STANDARD INDUSTRIAL CLASSIFICATION:** SERVICES-MEDICAL LABORATORIES [8071]
- **ORGANIZATION NAME:** 08 Industrial Applications and Services
- **EIN:** 770701774
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** S-8
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-291226
- **FILM NUMBER:** 251444398

**BUSINESS ADDRESS:**
- **STREET 1:** 505 S FRIENDSWOOD DRIVE
- **STREET 2:** SUITE 401
- **CITY:** FRIENDSWOOD
- **STATE:** TX
- **ZIP:** 77546
- **BUSINESS PHONE:** 866-788-9007

**MAIL ADDRESS:**
- **STREET 1:** 505 S FRIENDSWOOD DRIVE
- **STREET 2:** SUITE 401
- **CITY:** FRIENDSWOOD
- **STATE:** TX
- **ZIP:** 77546

**As filed with the Securities and Exchange Commission on November 3, 2025** 

**Registration No. 333-** 

    

**UNITED STATES** 

**SECURITIES AND EXCHANGE COMMISSION** 

**Washington, D.C. 20549** 

**FORM S-8** 

**REGISTRATION STATEMENT** 

***UNDER***

***THE SECURITIES ACT OF 1933***

**Castle Biosciences, Inc.** 

**(Exact name of registrant as specified in its charter)** 

---

| | |
|:---|:---|
| **Delaware** | **77-0701774** |
| **(State or other jurisdiction of**<br>**incorporation or organization)** | **(I.R.S. Employer**<br>**Identification No.)** |
| **505 S. Friendswood Drive, Suite 401**<br>**Friendswood, Texas** | **77546** |
| **(Address of Principal Executive Offices)** | **(Zip Code)** |

---

<br>**Castle Biosciences, Inc. 2022 Inducement Plan**

**(Full titles of the plans)** 

**Derek J. Maetzold** 

**President and Chief Executive Officer** 

**Castle Biosciences, Inc.** 

**505 S. Friendswood Drive, Suite 401** 

**Friendswood, Texas 77546** 

**(866) 788-9007** 

**(Name, address, including zip code, and telephone number, including area code, of agent for service)** 

***Copies to:***

**Thomas A. Coll, Esq.**<br>**Carlos Ramirez, Esq.**<br>**Cooley LLP**<br>**10265 Science Center Drive**<br>**San Diego, California 92121**<br>**(858) 550-6000**<br>

Indicate by check mark whether the Registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.

---

| | | | |
|:---|:---|:---|:---|
| Large accelerated filer | □ | Accelerated filer | ⌧ |
| Non-accelerated filer | □ | Smaller reporting company | □ |
| Emerging growth company | □ | | |

---

If an emerging growth company, indicate by check mark if the Registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. □

------

**EXPLANATORY NOTE**

This Registration Statement on Form S-8 (this "**Registration Statement**") is being filed by Castle Biosciences, Inc. (the "***Registrant***") with the Securities and Exchange Commission ("**SEC**") to register an additional 700,000 shares of common stock, par value $0.001 under the Castle Biosciences, Inc. 2022 Inducement Plan. In accordance with the instructional note to Part I of Form S-8 as promulgated by the SEC, the information specified by Part I of the Form S-8 has been omitted from this Registration Statement. Pursuant to General Instruction E to Form S-8, the contents of Registrant's registration statement on <u>[Form S-8 (File No. 333-270146)](https://www.sec.gov/Archives/edgar/data/1447362/000144736223000042/forms-8x2022inducementplan.htm)</u>, previously filed with the SEC on March 1, 2023, and Registrant's registration statement on <u>[Form S-8 (File No. 333-275881)](https://www.sec.gov/Archives/edgar/data/1447362/000144736223000161/forms-8x2022inducementplan.htm)</u>, previously filed with the SEC on December 4, 2023, are incorporated herein by reference, except that the provisions contained in Part II of such earlier registration statement are modified as set forth in this Registration Statement.

This Registration Statement is being filed for the purpose of registering additional securities of the same class as other securities for which registration statements of the Registrant on Form S-8 relating to the same employee benefit plans are effective

**PART II**

**INFORMATION REQUIRED IN THE REGISTRATION STATEMENT**

**ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.**

The Registrant hereby incorporates by reference into this Registration Statement the following documents previously filed by the Registrant with the SEC:

(a)The Registrant's Annual Report on Form 10-K for the year ended December 31, 2024, filed with the SEC on <u>[February 2](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001447362/000144736225000031/cstl-20241231.htm)[7](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001447362/000144736225000031/cstl-20241231.htm)[, 202](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001447362/000144736225000031/cstl-20241231.htm)[5](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001447362/000144736225000031/cstl-20241231.htm)</u> (and any portions of the Registrant's Definitive Proxy Statement on Schedule 14A filed on

<u>[April 9, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001447362/000144736225000054/cstl-20250407.htm)</u>, that are incorporated by reference into its Annual Report on Form 10-K for the year ended December 31, 2024).

(b)The Registrant's Quarterly Reports on Form 10-Q for the quarters ended March 31, 2025, June 30, 2025 and September 30, 2025, filed with the SEC on <u>[May](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001447362/000144736225000069/cstl-20250331.htm)[5](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001447362/000144736225000069/cstl-20250331.htm)[, 202](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001447362/000144736225000069/cstl-20250331.htm)[5](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001447362/000144736225000069/cstl-20250331.htm)</u>, <u>[August](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000144736225000097/cstl-20250630.htm)[4](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000144736225000097/cstl-20250630.htm)[, 202](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000144736225000097/cstl-20250630.htm)[5](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000144736225000097/cstl-20250630.htm)</u> and <u>[November](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000162828025048254/cstl-20250930.htm)[3](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000162828025048254/cstl-20250930.htm)[, 202](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000162828025048254/cstl-20250930.htm)[5](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000162828025048254/cstl-20250930.htm)</u>, respectively.

(c)The Registrant's Current Reports on Form 8-K, filed with the SEC on <u>[May 2](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000144736225000085/cstl-20250522.htm)[3](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000144736225000085/cstl-20250522.htm)[, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000144736225000085/cstl-20250522.htm)</u> and <u>[August](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000144736225000099/cstl-20250805.htm)[8](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000144736225000099/cstl-20250805.htm)[, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/1447362/000144736225000099/cstl-20250805.htm)</u>.

(d)The description of the Registrant's Common Stock contained in the Registrant's registration statement on <u>[Form 8-A](https://www.sec.gov/Archives/edgar/data/1447362/000114036119012956/nc10003252x1_8a12b.htm)</u> filed with the SEC on July 15, 2019, (File No. 001-38984) under Section 12(b) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), as updated by <u>[Exhibit 4.1](https://www.sec.gov/Archives/edgar/data/1447362/000144736220000029/exhibit41descriptionofsecu.htm)</u> to the Registrant's Annual Report on Form 10-K for the year ended December 31, 2019 filed with the SEC on March 10, 2020 (File No. 001-38984), including any amendment or report filed for the purpose of updating such description.

All documents, reports and definitive proxy or information statements filed by the Registrant pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this Registration Statement and prior to the filing of a post-effective amendment which indicates that all securities offered hereby have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference into this Registration Statement and to be a part hereof from the date of filing of such documents; provided, however, that documents, reports and definitive proxy or information statements, or portions thereof, which are furnished and not filed in accordance with the rules of the SEC shall not be deemed incorporated by reference into this Registration Statement unless specifically stated to the contrary. Any statement contained in a document incorporated or deemed to be incorporated herein by reference shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement herein or in any other subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes that statement. Any such statement so modified or superseded shall not constitute a part of this Registration Statement, except as so modified or superseded.

------

**ITEM 8. EXHIBITS.** 

---

| | |
|:---|:---|
| **Exhibit Number** | &nbsp;&nbsp;**Description** |
| 4.1 | <u>[Amended and Restated Certificate of Incorporation of the Registrant, incorporated by reference to Exhibit 3.1 of the Registrant's Current Report on Form 8-K filed with the SEC on May 23, 2025.](https://www.sec.gov/Archives/edgar/data/1447362/000144736225000085/exhibit-31.htm)</u> |
| 4.2 | <u>[Amended and Restated Bylaws of the Registrant, incorporated by reference to Exhibit 3.](https://www.sec.gov/Archives/edgar/data/1447362/000144736225000099/exhibit31-castlexamendedan.htm)[1](https://www.sec.gov/Archives/edgar/data/1447362/000144736225000099/exhibit31-castlexamendedan.htm)[to the Registrant's Current Report on Form 8-K, filed with the SEC on](https://www.sec.gov/Archives/edgar/data/1447362/000144736225000099/exhibit31-castlexamendedan.htm)[August 8](https://www.sec.gov/Archives/edgar/data/1447362/000144736225000099/exhibit31-castlexamendedan.htm)[, 20](https://www.sec.gov/Archives/edgar/data/1447362/000144736225000099/exhibit31-castlexamendedan.htm)[25](https://www.sec.gov/Archives/edgar/data/1447362/000144736225000099/exhibit31-castlexamendedan.htm)[.](https://www.sec.gov/Archives/edgar/data/1447362/000144736225000099/exhibit31-castlexamendedan.htm)</u> |
| 4.3 | <u>[Form of Common Stock Certificate of the Registrant. incorporated by reference to Exhibit 4.1 to the Registrant's Registration Statement on Form S-1 (File No. 333-232369), originally filed with the SEC on June 26, 2019, as amended.](https://www.sec.gov/Archives/edgar/data/1447362/000114036119012901/nt10000802x4_ex4-1.htm)</u> |
| 4.4 | <u>[Sixth Amended and Restated Investors' Rights Agreement, dated July 12, 2019, by and among the Registrant and certain of its stockholders, incorporated by reference to Exhibit 4.2 of the Registrant's Registration Statement on Form S-1 (File No. 333-232369), as amended, originally filed with the SEC on July 15, 2019.](https://www.sec.gov/Archives/edgar/data/1447362/000114036119012901/nt10000802x4_ex4-2.htm)</u> |
| 5.1\* | <u>[Opinion of Cooley LLP.](exhibit51-opinionofcooleyo.htm)</u> |
| 23.1\* | <u>[Consent of KPMG LLP, Independent Registered Public Accounting Firm.](exhibit231-kpmgsx8opiniono.htm)</u> |
| 23.2\* | <u>[Consent of Cooley LLP. Reference is made to Exhibit 5.1.](exhibit51-opinionofcooleyo.htm)</u> |
| 24.1\* | <u>[Power of Attorney. Reference is made to the signature page hereto.](#id583b37fb8f24f178987a52c10256404_4)</u> |
| 99.1 | <u>[Castle Biosciences, Inc. 2022 Inducement Plan, as amended and restated](https://www.sec.gov/Archives/edgar/data/1447362/000162828025048254/exhibit102castlebioscience.htm)[, incor](https://www.sec.gov/Archives/edgar/data/1447362/000162828025048254/exhibit102castlebioscience.htm)[porated by reference to Exhibit 10.2](https://www.sec.gov/Archives/edgar/data/1447362/000162828025048254/exhibit102castlebioscience.htm)[of the Registra](https://www.sec.gov/Archives/edgar/data/1447362/000162828025048254/exhibit102castlebioscience.htm)[nt's Quarterly Report on](https://www.sec.gov/Archives/edgar/data/1447362/000162828025048254/exhibit102castlebioscience.htm)[Form 10-Q filed with the SEC on November 3, 2025.](https://www.sec.gov/Archives/edgar/data/1447362/000162828025048254/exhibit102castlebioscience.htm)</u> |
| 99.2 | <u>[Forms of Restricted Stock Unit Grant Notice and Restricted Stock Unit Award Agreement under the Castle Biosciences, Inc. 2022 Inducement Plan, incorporated by reference to Exhibit 99.2 of the Registrant's Registration Statement on Form S-8 (File No. 333-270146), filed with the SEC on March 1, 2023.](https://www.sec.gov/Archives/edgar/data/1447362/000144736223000042/exhibit992-rsuagreementxin.htm)</u> |
| 99.3 | <u>[Forms of Stock Option Grant Notice, Option Agreement and Notice of Exercise under the Castle Biosciences, Inc. 2022 Inducement Plan, incorporated by reference to Exhibit 99.3 of the Registrant's Registration Statement on Form S-8 (File No. 333-270146), filed with the SEC on March 1, 2023.](https://www.sec.gov/Archives/edgar/data/1447362/000144736223000042/exhibit993-optionagreement.htm)</u> |
| 107\* | <u>[Filing Fee Table](exfilingfees.htm)</u> |

---

__________________________________

\*&nbsp;&nbsp;&nbsp;&nbsp;Filed herewith.

------

**SIGNATURES**

Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Friendswood, State of Texas, on November 3, 2025.

---

| | |
|:---|:---|
| &nbsp;&nbsp;&nbsp;**CASTLE BIOSCIENCES, INC.** | &nbsp;&nbsp;&nbsp;**CASTLE BIOSCIENCES, INC.** |
| &nbsp;&nbsp;&nbsp;By: | &nbsp;&nbsp;&nbsp;/s/ Derek J. Maetzold |
|  | &nbsp;&nbsp;&nbsp;Derek J. Maetzold |
|  | &nbsp;&nbsp;&nbsp;*President and Chief Executive Officer* |

---

**POWER OF ATTORNEY** 

KNOW ALL BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Derek J. Maetzold and Frank Stokes, and each of them, as his or her true and lawful attorneys-in-fact and agents, each with the full power of substitution, for him or her and in his or her name, place or stead, in any and all capacities, to sign any and all amendments to this Registration Statement (including post-effective amendments), and to file the same, with exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or their substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

------

---

| | | |
|:---|:---|:---|
| **Signature** | **Title** | **Date** |
| /s/ Derek J. Maetzold | President, Chief Executive Officer and Director | November 3, 2025 |
| Derek J. Maetzold | *(Principal Executive Officer)* |  |
| /s/ Frank Stokes | Chief Financial Officer | November 3, 2025 |
| Frank Stokes | *(Principal Financial and Accounting Officer)* |  |
| /s/ Daniel M. Bradbury | Chairperson of the Board of Directors | November 3, 2025 |
| Daniel M. Bradbury |  |  |
| /s/ Kimberlee S. Caple | Member of the Board of Directors | November 3, 2025 |
| Kimberlee S. Caple |  |  |
| /s/ G. Bradley Cole | Member of the Board of Directors | November 3, 2025 |
| G. Bradley Cole |  |  |
| /s/ Rodney Cotton | Member of the Board of Directors | November 3, 2025 |
| Rodney Cotton |  |  |
| /s/ Ellen Goldberg | Member of the Board of Directors | November 3, 2025 |
| Ellen Goldberg |  |  |
| /s/ Miles D. Harrison | Member of the Board of Directors | November 3, 2025 |
| Miles D. Harrison |  |  |
| /s/ Tiffany P. Olson | Member of the Board of Directors | November 3, 2025 |
| Tiffany P. Olson |  |  |

---

## Ex-Filing

?xml version='1.0' encoding='ASCII'? exfilingfees

**Exhibit 107**

**Calculation of Filing Fee Table**

**Form S-8**

**Castle Biosciences, Inc.**

<u>Table 1: Newly Registered Securities</u>

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| | **Security Type** | **Security<br>Class<br>Title** | **Fee Calculation Rule** | **Amount Registered** | **Proposed Maximum Offering Price Per Unit** | **Maximum Aggregate Offering Price** | **Fee<br>Rate** | **Amount of Registration Fee** |
| 1 | Equity | 2022 Inducement Plan, Common Stock, $0.001 per share | Other | 700000 | $24.32 | $17024000.00 | $0.0001381 | $2351.01 |
| Total Offering Amounts: | Total Offering Amounts: | Total Offering Amounts: | Total Offering Amounts: | Total Offering Amounts: |  | $17024000.00 |  | $2351.01 |
| Total Fee Offsets: | Total Fee Offsets: | Total Fee Offsets: | Total Fee Offsets: | Total Fee Offsets: |  |  |  | $0.00 |
| Net Fee Due: | Net Fee Due: | Net Fee Due: | Net Fee Due: | Net Fee Due: |  |  |  | $2351.01 |
| Offering Note | Offering Note | Offering Note | Offering Note | Offering Note | Offering Note | Offering Note | Offering Note | Offering Note |
| 1 | Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement shall also cover any additional shares of Common Stock, par value $0.001 per share ("Common Stock"), of Castle Biosciences, Inc. (the "Registrant") that become issuable under the Registrant's 2022 Inducement Plan (the "Inducement Plan") by reason of any stock dividend, stock split, recapitalization or other similar transaction.<br>The proposed maximum offering price per unit and proposed maximum aggregate offering price are estimated pursuant to Rule 457(h)(1) and Rule 457(c) of the Securities Act solely for purposes of calculating the registration fee, which is calculated based upon the average of the high and low prices of the Common Stock on October 27, 2025, as reported on the Nasdaq Global Market, which date is within five business days prior to the filing of this Registration Statement.<br>The amount registered represents the 700,000 shares of Common Stock added to the reserve of shares under the Inducement Plan as inducement grants under Nasdaq Listing Rule 5635(c)(4). | Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement shall also cover any additional shares of Common Stock, par value $0.001 per share ("Common Stock"), of Castle Biosciences, Inc. (the "Registrant") that become issuable under the Registrant's 2022 Inducement Plan (the "Inducement Plan") by reason of any stock dividend, stock split, recapitalization or other similar transaction.<br>The proposed maximum offering price per unit and proposed maximum aggregate offering price are estimated pursuant to Rule 457(h)(1) and Rule 457(c) of the Securities Act solely for purposes of calculating the registration fee, which is calculated based upon the average of the high and low prices of the Common Stock on October 27, 2025, as reported on the Nasdaq Global Market, which date is within five business days prior to the filing of this Registration Statement.<br>The amount registered represents the 700,000 shares of Common Stock added to the reserve of shares under the Inducement Plan as inducement grants under Nasdaq Listing Rule 5635(c)(4). | Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement shall also cover any additional shares of Common Stock, par value $0.001 per share ("Common Stock"), of Castle Biosciences, Inc. (the "Registrant") that become issuable under the Registrant's 2022 Inducement Plan (the "Inducement Plan") by reason of any stock dividend, stock split, recapitalization or other similar transaction.<br>The proposed maximum offering price per unit and proposed maximum aggregate offering price are estimated pursuant to Rule 457(h)(1) and Rule 457(c) of the Securities Act solely for purposes of calculating the registration fee, which is calculated based upon the average of the high and low prices of the Common Stock on October 27, 2025, as reported on the Nasdaq Global Market, which date is within five business days prior to the filing of this Registration Statement.<br>The amount registered represents the 700,000 shares of Common Stock added to the reserve of shares under the Inducement Plan as inducement grants under Nasdaq Listing Rule 5635(c)(4). | Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement shall also cover any additional shares of Common Stock, par value $0.001 per share ("Common Stock"), of Castle Biosciences, Inc. (the "Registrant") that become issuable under the Registrant's 2022 Inducement Plan (the "Inducement Plan") by reason of any stock dividend, stock split, recapitalization or other similar transaction.<br>The proposed maximum offering price per unit and proposed maximum aggregate offering price are estimated pursuant to Rule 457(h)(1) and Rule 457(c) of the Securities Act solely for purposes of calculating the registration fee, which is calculated based upon the average of the high and low prices of the Common Stock on October 27, 2025, as reported on the Nasdaq Global Market, which date is within five business days prior to the filing of this Registration Statement.<br>The amount registered represents the 700,000 shares of Common Stock added to the reserve of shares under the Inducement Plan as inducement grants under Nasdaq Listing Rule 5635(c)(4). | Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement shall also cover any additional shares of Common Stock, par value $0.001 per share ("Common Stock"), of Castle Biosciences, Inc. (the "Registrant") that become issuable under the Registrant's 2022 Inducement Plan (the "Inducement Plan") by reason of any stock dividend, stock split, recapitalization or other similar transaction.<br>The proposed maximum offering price per unit and proposed maximum aggregate offering price are estimated pursuant to Rule 457(h)(1) and Rule 457(c) of the Securities Act solely for purposes of calculating the registration fee, which is calculated based upon the average of the high and low prices of the Common Stock on October 27, 2025, as reported on the Nasdaq Global Market, which date is within five business days prior to the filing of this Registration Statement.<br>The amount registered represents the 700,000 shares of Common Stock added to the reserve of shares under the Inducement Plan as inducement grants under Nasdaq Listing Rule 5635(c)(4). | Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement shall also cover any additional shares of Common Stock, par value $0.001 per share ("Common Stock"), of Castle Biosciences, Inc. (the "Registrant") that become issuable under the Registrant's 2022 Inducement Plan (the "Inducement Plan") by reason of any stock dividend, stock split, recapitalization or other similar transaction.<br>The proposed maximum offering price per unit and proposed maximum aggregate offering price are estimated pursuant to Rule 457(h)(1) and Rule 457(c) of the Securities Act solely for purposes of calculating the registration fee, which is calculated based upon the average of the high and low prices of the Common Stock on October 27, 2025, as reported on the Nasdaq Global Market, which date is within five business days prior to the filing of this Registration Statement.<br>The amount registered represents the 700,000 shares of Common Stock added to the reserve of shares under the Inducement Plan as inducement grants under Nasdaq Listing Rule 5635(c)(4). | Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement shall also cover any additional shares of Common Stock, par value $0.001 per share ("Common Stock"), of Castle Biosciences, Inc. (the "Registrant") that become issuable under the Registrant's 2022 Inducement Plan (the "Inducement Plan") by reason of any stock dividend, stock split, recapitalization or other similar transaction.<br>The proposed maximum offering price per unit and proposed maximum aggregate offering price are estimated pursuant to Rule 457(h)(1) and Rule 457(c) of the Securities Act solely for purposes of calculating the registration fee, which is calculated based upon the average of the high and low prices of the Common Stock on October 27, 2025, as reported on the Nasdaq Global Market, which date is within five business days prior to the filing of this Registration Statement.<br>The amount registered represents the 700,000 shares of Common Stock added to the reserve of shares under the Inducement Plan as inducement grants under Nasdaq Listing Rule 5635(c)(4). | Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement shall also cover any additional shares of Common Stock, par value $0.001 per share ("Common Stock"), of Castle Biosciences, Inc. (the "Registrant") that become issuable under the Registrant's 2022 Inducement Plan (the "Inducement Plan") by reason of any stock dividend, stock split, recapitalization or other similar transaction.<br>The proposed maximum offering price per unit and proposed maximum aggregate offering price are estimated pursuant to Rule 457(h)(1) and Rule 457(c) of the Securities Act solely for purposes of calculating the registration fee, which is calculated based upon the average of the high and low prices of the Common Stock on October 27, 2025, as reported on the Nasdaq Global Market, which date is within five business days prior to the filing of this Registration Statement.<br>The amount registered represents the 700,000 shares of Common Stock added to the reserve of shares under the Inducement Plan as inducement grants under Nasdaq Listing Rule 5635(c)(4). |

---

## Exhibit 5.1

**Exhibit 5.1**

![cooleylogo2.jpg](cooleylogo2.jpg)

Carlos Ramirez

+1 858 550 6157

cramirez@cooley.com

November 3, 2025

Castle Biosciences, Inc.

505 S. Friendswood Drive, Suite 401

Friendswood, Texas 77546

Ladies and Gentlemen:

We have acted as counsel to Castle Biosciences, Inc., a Delaware corporation (the "***Company***"), in connection with the filing by the Company of a registration statement on Form S-8 (the "***Registration Statement***") with the Securities and Exchange Commission (the "***Commission***")covering the offering of up to 700,000 shares (the "***Shares***") of the Company's common stock, $0.001 par value per share (the "***Common Stock***"), issuable pursuant to the Company's 2022 Inducement Plan (the "***Plan***").

In connection with this opinion, we have examined and relied upon (i) the Registration Statement and related prospectuses, (ii) the Plan, (iii) the Company's certificate of incorporation and bylaws, each as currently in effect, and (iv) such other records, documents, opinions, certificates, memoranda and instruments as in our judgment are necessary or appropriate to enable us to render the opinion expressed below. We have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to originals of all documents submitted to us as copies, the accuracy, completeness and authenticity of certificates of public officials; and the due authorization, execution and delivery of all documents by all persons other than the Company. As to certain factual matters, we have relied upon a certificate of an officer of the Company and have not independently verified such matters.

Our opinion is expressed only with respect to the General Corporation Law of the State of Delaware. We express no opinion to the extent that any other laws are applicable to the subject matter hereof and express no opinion and provide no assurance as to compliance with any federal or state securities law, rule or regulation.

On the basis of the foregoing, and in reliance thereon, we are of the opinion that the Shares, when sold and issued in accordance with the Plan, the Registration Statement and the related prospectuses, will be validly issued, fully paid and nonassessable (except as to Shares issued pursuant to deferred payment arrangements, which will be fully paid and nonassessable when such deferred payments are made in full).

This opinion is limited to the matters expressly set forth in this letter, and no opinion has been or should be implied, or may be inferred, beyond the matters expressly stated. This opinion speaks only as to law and facts in effect or existing as of the date hereof, and we have no obligation or responsibility to update or supplement this opinion to reflect any facts or circumstances that may hereafter come to our attention or any changes in law that may hereafter occur.

Cooley LLP 10265 Science Center Drive, San Diego, CA 92121

t: (858) 550-6000 f: (858) 550-6420 cooley.com

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We consent to the filing of this opinion as an exhibit to the Registration Statement. In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act of 1933, as amended, or the rules and regulations of the Commission thereunder.

Sincerely,

Cooley LLP

By: <u>/s/ Carlos Ramirez</u>&nbsp;&nbsp;&nbsp;&nbsp;

Carlos Ramirez

Cooley LLP 10265 Science Center Drive, San Diego, CA 92121

t: (858) 550-6000 f: (858) 550-6420 cooley.com

## Exhibit 23.1

**Exhibit 23.1**

**Consent of Independent Registered Public Accounting Firm**

We consent to the use of our report dated February 27, 2025, with respect to the consolidated financial statements of Castle Biosciences, Inc., and the effectiveness of internal control over financial reporting, incorporated herein by reference.

/s/ KPMG LLP

Houston, Texas

November 3, 2025

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