Pfizer pours $25M investment into Caribou's cell therapies

Pfizer is backing Caribou Biosciences with a $25 million equity investment, money the genome editing company will pour into its allogeneic CAR-T cell therapy for multiple myeloma.

Pfizer purchased 4.6 million shares of Caribou common stock at $5.33 per share in a deal that added up to $25 million and closed June 30. Caribou, which boasts a pipeline of off-the-shelf cell therapies from its CAR-T and CAR-NK platforms, had $291 million in cash, cash equivalents and marketable securities as of March 31.

The California-based biotech will funnel the new money into CB-011, its allogeneic CAR-T cell therapy being studied in a phase 1 clinical trial in patients with relapsed or refractory multiple myeloma. The asset, which has secured fast-track designation from the FDA, is one of the first allogeneic CAR-T cell therapies to enter the clinic that is engineered to improve anti-tumor activity through an immune cloaking strategy, according to Caribou. The therapy targets the B-cell maturation antigen and is designed to remove the B2M protein and insert a B2M-HLA-E fusion protein that prevents immune-mediated rejection.

Pfizer is encouraged by Caribou’s CRISPR hybrid RNA-DNA guides gene editing tech—dubbed chRDNAs—and the potential allogeneic cell therapies have as off-the-shelf cancer treatments, Sriram Krishnaswami, Ph.D., Pfizer’s vice president and development head for multiple myeloma and global product development, said in a July 6 release. In connection with the equity investment, Krishnaswami is also joining Caribou’s scientific advisory board.  

Caribou has a lot to prove with its phase 1 trial ANTLER study for CB-010, which has enrolled patients with relapsed or refractory B cell non-Hodgkin lymphoma. Last year, just weeks after celebrating a 100% overall response rate, the biotech revealed that 50% of patients relapsed within six months of receiving its lead allogeneic CAR-T.  

Durability is a widespread issue for allogeneic CAR-T developers. In an attempt to tackle CAR-T cell exhaustion and maintain high anti-tumor activity for a longer time, Caribou had removed the PD-1 receptors from its anti-CD19 candidate CB-010. However, last year’s results raise questions about the impact of the work to boost durability.

The relapses overshadowed other, more encouraging aspects of the data, like the 100% complete response rate at the starting dose of 40 million CAR-T cells and no high-grade safety events.  

Based on the data, Caribou started enrolling patients at the second dose level, 80 million CAR-T cells. Doubling the dose could drive longer-lasting responses, enabling Caribou to differentiate itself from the rest of the allogeneic CAR-T space and renew confidence in its durability approach.

To date, CB-010 has garnered regenerative medicine advanced therapy, fast-track and orphan tags from the FDA. Within the next six months, Caribou plans to share six-month dose escalation data on the candidate, Caribou CEO Rachel Haurwitz, Ph.D., said in the company’s release.

Editor's note: This article was updated July 6 at 2:00 p.m. ET to change CB-011 to CB-010 in the fifth paragraph.