FDA grants RMAT designation to Caribou (CRBU) CAR-T CB-011 in multiple myeloma
Filing Impact
Filing Sentiment
Form Type
8-K
Rhea-AI Filing Summary
Caribou Biosciences reported that the FDA granted Regenerative Medicine Advanced Therapy (RMAT) designation to CB-011, its allogeneic anti-BCMA CAR-T cell therapy for relapsed or refractory multiple myeloma. The designation is based on phase 1 CaMMouflage trial dose-escalation data in a 12-patient BCMA-naïve cohort, which showed a 92% overall response rate, a 75% complete response or better rate, and 91% minimal residual disease negativity at the recommended expansion dose. Forty-eight patients have been treated in dose escalation, and the ongoing dose expansion is testing a 450x106 CAR-T cell dose in both BCMA-naïve and BCMA-exposed patients, with additional data expected in 2026. CB-011 has shown a manageable safety profile, with common treatment-emergent adverse events including neutropenia, anemia, thrombocytopenia, infections, and cytokine release syndrome.
Positive
- FDA RMAT designation for CB-011 in relapsed/refractory multiple myeloma based on early CaMMouflage phase 1 data, potentially enabling expedited development and review pathways.
- Strong early efficacy signals for CB-011 at the recommended dose in BCMA-naïve patients, with 92% overall response, 75% ≥ complete response, and 91% minimal residual disease negativity.
Negative
- None.
Insights
RMAT designation for CB-011 signals FDA recognition of promising early multiple myeloma data.
The FDA granting RMAT designation to CB-011 in relapsed or refractory multiple myeloma is a meaningful regulatory step. RMAT status is reserved for regenerative therapies targeting serious conditions with preliminary clinical evidence of substantial improvement over existing options, and it can enable accelerated pathways.
The supporting CaMMouflage phase 1 dose-escalation data in 12 BCMA-naïve patients at the recommended dose showed a 92% overall response rate, 75% complete response or better rate, and 91% minimal residual disease negativity, alongside a manageable safety profile without certain serious neurologic or graft-versus-host events. These results justify closer attention as the program advances.
RMAT provides enhanced FDA interaction and eligibility for expedited review, which may help shape CB-011’s future development strategy. The company plans to continue enrolling BCMA-naïve and BCMA-exposed patients in dose expansion and to present additional data from the CaMMouflage trial in 2026, which will further clarify durability, safety, and scalability of this off-the-shelf CAR-T approach.
8-K Event Classification
3 items: 7.01, 8.01, 9.01
3 items
Item 7.01
Regulation FD Disclosure
Disclosure
Material non-public information disclosed under Regulation Fair Disclosure, often investor presentations or guidance.
Item 8.01
Other Events
Other
Voluntary disclosure of events the company deems important to shareholders but not covered by other items.
Item 9.01
Financial Statements and Exhibits
Exhibits
Financial statements, pro forma financial information, and exhibit attachments filed with this report.
Key Figures
Patients treated in dose escalation: 48 patients
Recommended dose for expansion: 450x10^6 CAR-T cells
Overall response rate: 92%
+5 more
8 metrics
Patients treated in dose escalation
48 patients
CaMMouflage phase 1 trial for CB-011
Recommended dose for expansion
450x10^6 CAR-T cells
CB-011 CaMMouflage phase 1 trial
Overall response rate
92%
12 BCMA-naïve r/r MM patients at recommended dose
≥ Complete response rate
75%
12 BCMA-naïve r/r MM patients at recommended dose
MRD negativity
91%
10 of 11 evaluable BCMA-naïve patients at recommended dose
Neutropenia incidence
80%
Treatment-emergent adverse events in 35 patients at selected LD
Anemia incidence
60%
Treatment-emergent adverse events in 35 patients at selected LD
Cytokine release syndrome incidence
31%
Treatment-emergent adverse events in 35 patients at selected LD
Key Terms
Regenerative Medicine Advanced Therapy (RMAT) designation, allogeneic CAR-T cell therapy, minimal residual disease (MRD) negativity, lymphodepletion (LD) regimen, +2 more
6 terms
Regenerative Medicine Advanced Therapy (RMAT) designation regulatory
"the FDA has granted Regenerative Medicine Advanced Therapy (RMAT) designation to CB-011"
A Regenerative Medicine Advanced Therapy (RMAT) designation is a U.S. regulatory status given to certain cell, gene, or tissue-based treatments that show promise for serious conditions and early clinical evidence of benefit. It signals that regulators will provide extra guidance and expedited review steps—like giving a promising project a “fast pass” through some development checkpoints—which can shorten time to market and reduce regulatory risk, making the program more valuable and noteworthy to investors.
allogeneic CAR-T cell therapy medical
"CB-011, an allogeneic anti-BCMA CAR-T cell therapy, is being evaluated"
A therapy in which immune cells taken from a healthy donor are genetically reprogrammed to recognize and kill cancer cells and then given to a patient; think of it as an off‑the‑shelf, engineered immune weapon rather than one made from the patient’s own tissue. It matters to investors because this approach can be faster and cheaper to manufacture at scale than patient‑specific therapies, but carries additional risks such as immune rejection, regulatory hurdles and complex manufacturing that affect clinical success, costs and commercial potential.
minimal residual disease (MRD) negativity medical
"91% (10/11 evaluable) minimal residual disease (MRD) negativity"
lymphodepletion (LD) regimen medical
"treated with CB-011 following the selected lymphodepletion (LD) regimen"
treatment emergent adverse events (TEAEs medical
"Treatment emergent adverse events (TEAEs) in ≥25% of all patients"
Fast Track and Orphan Drug designations regulatory
"The FDA granted CB-011 Regenerative Medicine Advanced Therapy (RMAT), Fast Track, and Orphan Drug designations"
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): March 31, 2026
________________________________________
(Exact name of Registrant as Specified in Its Charter)
________________________________________
| (State or Other Jurisdiction of Incorporation) | (Commission File Number) | (IRS Employer Identification No.) | ||||||
| (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:
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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 7.01 Regulation FD Disclosure.
On March 31, 2026, Caribou Biosciences, Inc. (the “Company”) issued a press release announcing that it received Regenerative Medicine Advanced Therapy (“RMAT”) designation for relapsed or refractory multiple myeloma ("r/r MM") from the U.S. Food and Drug Administration (“FDA”) for CB-011, the Company's allogeneic anti-BCMA CAR-T cell therapy product candidate. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K and also is incorporated by reference into this Item 7.01.
The information in this Item 7.01, including the accompanying Exhibit 99.1, 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, or incorporated by reference in any filing or other document under the Exchange Act or the Securities Act of 1933, as amended, regardless of any general incorporation language in any such filing or document, except as shall be expressly set forth by specific reference in any such filing or document.
Item 8.01 Other Events.
On March 31, 2026 , the Company announced that it received RMAT designation for r/r MM from the FDA for CB-011, its allogeneic anti-BCMA CAR-T cell therapy product candidate. CB-011 is currently being evaluated in the Company’s ongoing CaMMouflage phase 1 clinical trial.
Item 9.01 Financial Statements and Exhibits.
(d) Exhibits
| Exhibit No. | Description | |||||||
| 99.1 | Press Release Issued by Caribou Biosciences, Inc. on March 31, 2026 | |||||||
| 104 | Cover 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 thereunto duly authorized.
| Caribou Biosciences, Inc. | |||||||||||
| Date: | March 31, 2026 | By: | /s/ Rachel E. Haurwitz | ||||||||
Rachel E. Haurwitz President and Chief Executive Officer | |||||||||||
Exhibit 99.1
Caribou Biosciences Announces the FDA Granted Regenerative Medicine Advanced Therapy (RMAT) Designation to CB-011, an Allogeneic Anti-BCMA CAR-T Cell Therapy
-- RMAT granted based on promising initial clinical data, including previously disclosed recommended dose for expansion data of 92% ORR, 75% ≥CR rate, 91% MRD negativity in the 12-patient, BCMA-naïve r/r MM patient cohort --
-- Ongoing dose expansion enrollment in CaMMouflage phase 1 clinical trial includes BCMA-naïve and BCMA-exposed cohorts; initial dose expansion and longer follow up on dose escalation data expected in 2026 --
BERKELEY, Calif., March 31, 2026 -- Caribou Biosciences, Inc. (Nasdaq: CRBU), a leading clinical-stage CRISPR genome-editing biopharmaceutical company, today announced that the U.S. Food and Drug Administration (FDA) has granted Regenerative Medicine Advanced Therapy (RMAT) designation to CB-011 for relapsed or refractory multiple myeloma (r/r MM). CB-011, an allogeneic anti-BCMA CAR-T cell therapy, is being evaluated in the company’s ongoing open-label, multicenter CaMMouflage phase 1 clinical trial evaluating patients with r/r MM.
“Only one in 10 people with multiple myeloma in the U.S. are able to receive CAR-T cell therapies due to long wait times and manufacturing limitations,” said Adriana Rossi, MD, director of CAR-T and stem cell transplant clinical program at the center of excellence for multiple myeloma at Mount Sinai and an investigator on the CaMMouflage trial. “This highlights a critical gap in access for patients with relapsed or refractory disease. An off-the-shelf CAR-T cell therapy like CB-011 could help bridge that gap by offering a readily available treatment option to a broader group of patients.”
As previously reported in November 2025, 48 patients have been treated in the dose escalation portion of the company’s CaMMouflage phase 1 clinical trial. The 450x106 CAR-T cell dose was selected as the recommended dose for expansion (RDE). In dose escalation, 12 BCMA-naïve patients were treated with the RDE; efficacy outcomes from this cohort included a 92% (11/12) overall response rate (ORR), 75% (9/12) ≥ complete response (CR) rate, and 91% (10/11 evaluable) minimal residual disease (MRD) negativity as of a September 24, 2025, data cutoff. CB-011 has demonstrated a manageable safety profile, with no cases of graft-versus-host disease, immune effector cell-associated enterocolitis, parkinsonism, or cranial nerve palsies observed at any dose level. Treatment emergent adverse events (TEAEs) in ≥25% of all patients treated with CB-011 following the selected lymphodepletion (LD) regimen (N=35) were as follows: neutropenia (80%), anemia (60%), thrombocytopenia (49%), infections (49%), dizziness (31%), cytokine release syndrome (31%), fatigue (31%), leukopenia (29%), decreased appetite (29%), constipation (26%), and pyrexia (26%) as of the data cutoff date.
“The FDA’s RMAT designation for CB-011 recognizes both the significant unmet need in multiple myeloma and the encouraging clinical data we have seen so far in the CaMMouflage trial,” said Tina Albertson, MD, PhD, chief medical officer at Caribou Biosciences. “The dose escalation data highlight the potential of CB-011 as the best-in-class allogeneic CAR-T cell therapy for relapsed or refractory multiple myeloma. We look forward to initiating discussion with the FDA regarding future clinical development of CB-011 and to reporting additional data this year as we continue to enroll both BCMA-naïve and BCMA-exposed patients in dose expansion.”
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RMAT designation is a dedicated program designed to expedite the development and review processes for promising therapeutic candidates intended to address an unmet medical need in patients with serious conditions. This designation provides important benefits in the drug development process and is designed to facilitate and expedite development and regulatory review, including providing eligibility for priority and rolling reviews and accelerated approval, if relevant criteria are satisfied.
About CB-011
CB-011 is an allogeneic anti-BCMA CAR-T cell therapy being evaluated in patients with relapsed or refractory multiple myeloma (r/r MM). To Caribou’s knowledge, CB-011 is the first allogeneic CAR-T cell therapy in the clinic that is engineered to enable activity through an immune cloaking strategy with a B2M knockout and insertion of a B2M–HLA-E fusion protein to blunt immune-mediated rejection. The FDA granted CB-011 Regenerative Medicine Advanced Therapy (RMAT), Fast Track, and Orphan Drug designations for r/r MM.
About the CaMMouflage phase 1 clinical trial
The CaMMouflage clinical trial is a multicenter, open-label phase 1 trial evaluating CB-011 in adults with r/r MM who have been treated with three or more prior lines of therapy. Using a 3+3 dose escalation design, safety and efficacy of CB-011 were evaluated in 48 patients at multiple dose levels and two different lymphodepletion (LD) regimens. Thirteen patients were treated with a single dose of CB-011 (50x106 [N=3], 150x106 [N=7], and 450x106 [N=3] CAR-T cells) with an LD regimen of 300 mg/m2 cyclophosphamide and 30 mg/m2 fludarabine daily for three days, and 35 patients were treated with a single dose of CB-011 (150x106 [N=6], 300x106 [N=13], 450x106 [N=13], and 800x106 [N=3] CAR-T cells) with an LD regimen of 500 mg/m2 cyclophosphamide and 30 mg/m2 fludarabine daily for three days. The ongoing dose expansion portion of the trial will evaluate safety and efficacy of CB-011 at 450x106 CAR-T cells with the selected LD of 500 mg/m2 cyclophosphamide and 30 mg/m2 fludarabine daily for three days. Additional information on the CaMMouflage trial (NCT05722418) can be found at www.clinicaltrials.gov.
About Caribou Biosciences, Inc.
Caribou is a clinical-stage CRISPR genome-editing biopharmaceutical company dedicated to developing transformative therapies for patients with devastating diseases. Caribou’s genome-editing platform based on its chRDNA genome-editing technology enables superior precision to develop cell therapies that are armored to potentially improve activity against diseases. Caribou is focused on vispacabtagene regedleucel (vispa-cel) and CB-011 as off-the-shelf CAR-T cell therapies that have the potential to provide broad access and rapid treatment for patients with hematologic malignancies. Follow the Company @CaribouBio and visit www.cariboubio.com.
Forward-looking statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential,” or “continue,” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these words. These forward-looking statements include, but are not limited to, any statements regarding the initiation, timing, progress, strategy, plans, objectives, expectations (including as to the results) with
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respect to the Company’s CAR-T cell therapy product candidate clinical trials, including its expectations regarding reporting dose expansion data, along with longer follow-up data on dose escalation, in 2026 from its ongoing CaMMouflage phase 1 clinical trial for CB-011 in patients with r/r MM; its expectations relating to discussions with the FDA regarding future clinical development of CB-011; its ability to successfully develop its CAR-T cell therapy product candidates and to obtain and maintain regulatory approval for these product candidates; the likelihood of its clinical trials demonstrating safety and efficacy of its CAR-T cell therapy product candidates; the beneficial characteristics, safety, efficacy, therapeutic effects, and potential advantages of its CAR-T cell therapy product candidates; and the expected timing or likelihood of regulatory filings and approval for its CAR-T cell therapy product candidates. Management believes that these forward-looking statements are reasonable as and when made. However, such forward-looking statements are subject to risks and uncertainties, and actual results may differ materially from any future results expressed or implied by the forward-looking statements. Risks and uncertainties include, without limitation, risks inherent in the development of allogeneic CAR-T cell therapy products; uncertainties related to the initiation, cost, timing, progress, and results of its current and future clinical trials; the risk that initial, preliminary, or interim clinical trial data will not ultimately be predictive of the safety and efficacy of its CAR-T cell therapy product candidates or that clinical outcomes may differ as patient enrollment continues and as more patient data becomes available; the risk that different conclusions or considerations are reached once additional data have been received and fully evaluated; the ability to obtain key regulatory input and approvals; and risks related to its limited operating history, history of net operating losses, financial position, and its ability to raise additional capital as needed to fund its operations and CAR-T cell therapy product candidate development, including the ability to fully fund its pivotal phase 3 clinical trial for vispa-cel; as well as other risk factors described from time to time in Caribou’s filings with the Securities and Exchange Commission (SEC), including its Annual Report on Form 10-K for the year ended December 31, 2025, and subsequent SEC filings. In light of the significant uncertainties in these forward-looking statements, you should not rely upon forward-looking statements as predictions of future events. Except as required by law, Caribou undertakes no obligation to update publicly any forward-looking statements for any reason.
Caribou Biosciences, Inc. contact:
Peggy Vorwald, PhD
investor.relations@cariboubio.com
media@cariboubio.com
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FAQ
What did Caribou Biosciences (CRBU) announce about CB-011 and the FDA?
Caribou Biosciences announced the FDA granted RMAT designation to CB-011 for relapsed or refractory multiple myeloma. This status recognizes promising early data and can expedite development, offering more frequent FDA interaction and potential priority or accelerated review.
What early clinical results support RMAT designation for Caribou’s CB-011?
RMAT designation is supported by CaMMouflage phase 1 dose-escalation data in 12 BCMA-naïve patients at the recommended dose, showing 92% overall response, 75% complete response or better, and 91% minimal residual disease negativity, indicating strong early activity in heavily pretreated multiple myeloma.
How many patients have received CB-011 in the CaMMouflage phase 1 trial?
Forty-eight patients with relapsed or refractory multiple myeloma have been treated with CB-011 in the dose-escalation portion of the CaMMouflage phase 1 trial, across multiple dose levels and two lymphodepletion regimens, providing a broad initial safety and activity dataset.
What is the recommended dose for expansion of CB-011 in CaMMouflage?
The recommended dose for expansion in the CaMMouflage trial is 450x106 CAR-T cells with a specific cyclophosphamide and fludarabine lymphodepletion regimen. This dose was chosen based on safety and efficacy signals observed during the dose-escalation phase in relapsed or refractory multiple myeloma patients.
What safety profile has CB-011 shown so far in clinical testing?
CB-011 has shown a manageable safety profile, with no graft-versus-host disease, immune effector cell-associated enterocolitis, parkinsonism, or cranial nerve palsies reported. Common treatment-emergent adverse events included neutropenia, anemia, thrombocytopenia, infections, and cytokine release syndrome in at least 25% of treated patients.
What makes CB-011 distinct among allogeneic CAR-T therapies?
CB-011 is described as the first allogeneic CAR-T therapy in the clinic engineered with an immune-cloaking strategy, combining B2M knockout and a B2M–HLA-E fusion protein. This design aims to blunt immune-mediated rejection and potentially improve persistence and activity in multiple myeloma treatment.
Filing Exhibits & Attachments
4 documents
Caribou Biosciences, Inc.
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Feb 25, 2026
[144] Caribou Biosciences, Inc. SEC Filing
Feb 25, 2026
[144] Caribou Biosciences, Inc. SEC Filing
CRBU Stock Data
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Biotechnology
Biological Products, (no Diagnostic Substances)
United States
BERKELEY