CRBU

crbu-20251112FALSE000161985600016198562025-11-122025-11-12

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 12, 2025

Caribou Biosciences, Inc. (Exact name of Registrant as Specified in Its Charter)

Delaware001-4063145-3728228 (State or Other Jurisdiction of Incorporation)(Commission File Number)(IRS Employer Identification No.)

2929 7th Street, Suite 105 Berkeley, California 94710 (Address of Principal Executive Offices)(Zip Code)

Registrant’s Telephone Number, Including Area Code: (510) 982-6030 N/A (Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each classTrading Symbol(s) Name of each exchange on which registered Common Stock, $0.0001 par value per shareCRBUNASDAQ Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter). 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 13(a) of the Exchange Act. ☐

Item 2.02 Results of Operations and Financial Condition. On November 12, 2025, Caribou Biosciences, Inc., a Delaware corporation (the “Company”), issued a press release announcing the Company’s financial results for the quarter ended September 30, 2025, and providing a business update. A copy of this press release is furnished as Exhibit 99.1 and is incorporated herein by reference.

The information in Item 2.02 of this Current Report on Form 8-K (including Exhibit 99.1 attached hereto) is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference into any filing by the Company, under the Securities Act of 1933, as amended, or the Exchange Act, regardless of any general incorporation language in any such filing, except as expressly set forth by specific reference in such filing.

Item 9.01 Financial Statements and Exhibits. (d) Exhibits

Exhibit No.Description 99.1Press Release Issued by Caribou Biosciences, Inc. on November 12, 2025

104Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Caribou Biosciences, Inc.

Date:November 12, 2025By:  /s/ Rachel E. Haurwitz Rachel E. Haurwitz, Ph.D. President and Chief Executive Officer

crbu-20251103FALSE000161985600016198562025-11-032025-11-03

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 3, 2025

Caribou Biosciences, Inc. (Exact name of Registrant as Specified in Its Charter)

Delaware001-4063145-3728228 (State or Other Jurisdiction of Incorporation)(Commission File Number)(IRS Employer Identification No.)

2929 7th Street, Suite 105 Berkeley, California 94710 (Address of Principal Executive Offices)(Zip Code)

Registrant’s Telephone Number, Including Area Code: (510) 982-6030 N/A (Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each classTrading Symbol(s) Name of each exchange on which registered Common Stock, $0.0001 par value per shareCRBUNASDAQ Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter). 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 13(a) of the Exchange Act. ☐

Item 2.02 Results of Operations and Financial Condition On November 3, 2025, Caribou Biosciences, Inc. (the “Company”) announced certain preliminary financial results for the quarter ended September 30, 2025. On a preliminary unaudited basis, the Company expects its cash, cash equivalents, and marketable securities as of September 30, 2025 to be approximately $159.2 million. This estimate of cash, cash equivalents, and marketable securities is its preliminary estimate based on currently available information and does not present all necessary information for an understanding of the Company’s financial condition as of September 30, 2025, or its results of operations for the three and nine months ended September 30, 2025. As the Company completes its quarter-end financial close process and finalizes its financial statements for the three and nine months ended September 30, 2025, the Company may be required to make significant adjustments that may result in the estimate provided herein being different than the final cash, cash equivalents, and marketable securities as of September 30, 2025 to be reported in its Form 10-Q.

Item 7.01 Regulation FD Disclosure. On November 3, 2025, the Company issued a press release announcing results from its ongoing ANTLER phase 1 trial evaluating vispacabtagene regedleucel (“vispa-cel;” formerly CB-010), an allogeneic anti-CD19 chimeric antigen receptor ("CAR")-T (“CAR-T”) cell therapy, in patients with relapsed or refractory B cell non-Hodgkin lymphoma (“r/r B-NHL”). The Company also announced the planned design of its randomized, controlled pivotal phase 3 trial for vispa-cel in second-line (“2L”) large B cell lymphoma (“LBCL”) CD19-naïve patients who are ineligible for transplant and autologous CAR-T cell therapy. A copy of the press release is attached hereto as Exhibit 99.1 and incorporated by reference herein. Also, on November 3, 2025, the Company issued a press release announcing data from the dose escalation portion of its ongoing CaMMouflage phase 1 trial evaluating CB-011, an allogeneic anti-B cell maturation antigen (“anti-BCMA”) CAR-T cell therapy, in patients with relapsed or refractory multiple myeloma (“r/r MM”). A copy of the press release is attached hereto as Exhibit 99.2 and incorporated by reference herein. The Company will host a live webcast today, Monday, November 3, 2025, at 8:00 a.m. Eastern Time, to discuss the clinical developments for both vispa-cel and CB-011. A copy of the slide presentation to be used during the Company’s webcast is attached hereto as Exhibit 99.3 and incorporated by reference herein. Details for accessing the webcast are included in both Exhibit 99.1 and Exhibit 99.2. The information in Item 7.01 of this Current Report on F

crbu-20250812FALSE000161985600016198562025-08-122025-08-12

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 12, 2025

Caribou Biosciences, Inc. (Exact name of Registrant as Specified in Its Charter)

Delaware001-4063145-3728228 (State or Other Jurisdiction of Incorporation)(Commission File Number)(IRS Employer Identification No.)

2929 7th Street, Suite 105 Berkeley, California 94710 (Address of Principal Executive Offices)(Zip Code)

Registrant’s Telephone Number, Including Area Code: (510) 982-6030 N/A (Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each classTrading Symbol(s) Name of each exchange on which registered Common Stock, $0.0001 par value per shareCRBUNASDAQ Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter). 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 13(a) of the Exchange Act. ☐

Item 2.02 Results of Operations and Financial Condition. On August 12, 2025, Caribou Biosciences, Inc., a Delaware corporation (the “Company”), issued a press release announcing the Company’s financial results for the quarter ended June 30, 2025, and providing a business update. A copy of this press release is furnished as Exhibit 99.1 and is incorporated herein by reference.

The information in Item 2.02 of this Current Report on Form 8-K (including Exhibit 99.1 attached hereto) is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference into any filing by the Company, under the Securities Act of 1933, as amended, or the Exchange Act, regardless of any general incorporation language in any such filing, except as expressly set forth by specific reference in such filing.

Item 9.01 Financial Statements and Exhibits. (d) Exhibits

Exhibit No.Description 99.1Press Release Issued by Caribou Biosciences, Inc. on August 12, 2025

104Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Caribou Biosciences, Inc.

Date:August 12, 2025By:  /s/ Rachel E. Haurwitz Rachel E. Haurwitz, Ph.D. President and Chief Executive Officer