Caribou Biosciences, Inc. 8-K

What Happened

• Caribou Biosciences announced long-term follow-up results from its ANTLER phase 1 trial of vispa-cel (allogeneic anti‑CD19 CAR‑T) in relapsed/refractory B‑cell non‑Hodgkin lymphoma and updated dose‑escalation results from the CaMMouflage phase 1 trial of CB‑011 (allogeneic anti‑BCMA CAR‑T) in relapsed/refractory multiple myeloma. The company will present vispa-cel data at EHA on June 12, 2026, and CB‑011 data on June 14, 2026.
• The filing also confirms alignment with the FDA on the design of ANTLER‑3, a randomized pivotal phase 3 trial planned to enroll ~250 CD19‑naïve second‑line large B cell lymphoma (2L LBCL) patients, with progression‑free survival (PFS) as the primary endpoint and crossover permitted after progression.

Key Details

• ANTLER (vispa-cel) pivotal optimized subgroup (N=27, dose = 80 million optimized cells): 82% overall response rate (ORR); 67% complete response (CR); median PFS = 17.1 months. No graft‑versus‑host disease (GvHD) or grade ≥3 ICANS reported; one (4%) grade ≥3 CRS; one vispa‑cel‑related death (IEC‑HS); one possibly related death (PML).
• ANTLER‑3 design: randomized vs investigator’s choice SOC (Pola‑BR, R‑GemOx, Pola‑RGO, or tafasitamab + lenalidomide); ~75 global sites; patients not eligible for transplant or autologous CAR‑T.
• CaMMouflage (CB‑011) dose‑escalation: recommended dose for expansion (RDE) = 450 million cells with selected lymphodepletion; BCMA‑naïve RDE cohort (N=12, median follow‑up 17.7 months): 92% ORR; 83% ≥CR; 91% MRD negativity (10/11 evaluable); 50% in ≥CR at 15 months.
• CB‑011 safety (selected LD regimen): no GvHD, enterocolitis, parkinsonism, or cranial nerve palsies (N=48 overall); in RDE cohort no grade ≥3 ICANS, one (8%) grade ≥3 CRS, 25% grade ≥3 infections, 42% prolonged grade ≥3 cytopenias; one CB‑011‑related death (hematotoxicity) among patients treated with selected LD (N=35).

Why It Matters

• These results show meaningful response rates and signal durability in early‑stage, allogeneic CAR‑T programs: vispa‑cel’s optimized subgroup produced high ORR/CR and a median PFS of 17.1 months, and CB‑011 demonstrated deep responses and MRD negativity in heavily pretreated myeloma patients. The FDA alignment and planned ANTLER‑3 pivotal trial provide a clear path to a registrational study for vispa‑cel.
• For investors, the filings mark clinical progress (data readouts and a planned phase 3) that could materially affect the company’s development timeline and value, while also highlighting safety events (including treatment‑related deaths and hematologic toxicities) that remain important risks. Caribou also expects to report CaMMouflage dose‑expansion data in the second half of 2026.