Pfizer Jumps into the CD47 Race With $2.3B Buyout of Trillium

After the commercial success of monoclonal antibodies targeting the PD-1 and PD-L1 pathway, companies are racing to find the next big checkpoint inhibitor target. One of the novel pathways garnering a lot of attention and capital is the CD47 pathway. CD47 is a “don’t eat me” signal overexpressed on many cancers. By presenting it to the signal regulatory protein alpha (SIRP-alpha) and forming a complex with them, the cancer cell escapes attacks from the immune system.

Last year Gilead acquired Forty Seven, a company developing CD47 targeting monoclonal antibodies, for $4.9 billion. For their part, AbbVie announced a partnership with I-Mab, a Shanghai-based company worth almost $2 billion, to develop a therapeutic targeting CD47. Earlier this year, Arch Oncology raised $105 million in Series C financing to develop its anti-CD47 targeting antibodies.

Now Pfizer has decided not to wait for its bispecific antibody to enter clinical trials and jump into the race. Instead, it has leaped forward by acquiring Trillium, a Massachusetts-based company developing anti-CD47 antibodies. Last year, Pfizer invested $25 million in Trillium, but it announced it would acquire all outstanding shares of Trillium for a total of $2.26 billion, or $18.50 per share in cash. That is more than 3 times higher than the closing cost of Trillium’s stock on Friday. After the announcement, the stock skyrocketed 188.8% to close at $17.59.

Bolstering the Immuno-Oncology Pipeline

From the acquisition, Pfizer will strengthen its position in immuno-oncology by adding TTI-621 and TTI-622 to its portfolio. Both therapies block the interaction of CD47 and signal-regulatory protein α (SIRPα). Blocking the interaction signals the innate immune cells, especially macrophages, to attack the cancer cells. However, the therapeutics differ on the intensity of the signal they provide to the immune cells. TTI-621 delivers a strong activating signal, while TTI-622 provides a moderate signal. 

Both are currently in Phase 1b/2 clinical trials for a variety of hematological malignancies. Both have demonstrated monotherapy activity in Diffuse Large B-cell Lymphoma (DLBCL), Peripheral T-cell lymphoma (PTCL), Follicular Lymphoma (FL), and others. There are also plans to test the efficacy of both therapies alone or in combination with other agents to treat solid tumors.  

“We are encouraged by the early clinical data for TTI-622 and TTI-621 monotherapy for patients with heavily pretreated lymphoid malignancies and early encouraging activity for TTI-622 in patients with multiple myeloma. Just as PD-1 and PD-L1 blockers have proven to be effective immuno-therapeutics for many solid tumors, the SIRPα-CD47 interaction defines a second key immune checkpoint for which disrupting agents are expected to become another important backbone immunotherapy for multiple types of cancer, especially hematological cancers,” said Chris Boshoff, MD, Ph.D., Chief Development Officer, Oncology, Pfizer Global Product Development. 

“Utilizing Pfizer’s leading research and global development capabilities, we plan to accelerate the clinical development of SIRPα fusion proteins as a potential new scientific breakthrough and explore combinations within our own portfolio and with innovative next-generation medicines for hematological malignancies.”

Author

Daniel Ojeda