Trillium Therapeutics

The company's core business revolved around its portfolio of biologics designed to enhance the innate immune system's ability to detect and destroy cancer cells. A significant milestone in the company's history was its acquisition by Pfizer in November 2021 for an aggregate purchase price of approximately $2.22 billion. This acquisition followed an initial investment of $25 million by Pfizer in September 2020 through its Breakthrough Growth Initiative, which also led to a Pfizer executive joining Trillium's Scientific Advisory Board. The acquisition was structured as a statutory plan of arrangement under the Business Corporations Act of British Columbia, resulting in Trillium becoming a wholly-owned subsidiary of Pfizer and its shares being delisted from the Nasdaq and Toronto Stock Exchange.

Trillium's main products in development were two lead molecules, TTI-622 and TTI-621, which are novel SIRPα-Fc fusion proteins. These proteins function by blocking the signal-regulatory protein α (SIRPα)–CD47 axis, an immune checkpoint that cancer cells use to send a "don't eat me" signal to evade destruction by the immune system. The technology was designed to not only block this inhibitory signal but also to deliver a pro-phagocytic "eat me" signal to macrophages. A key feature of these molecules is their design to have limited binding to red blood cells, mitigating the risk of anemia, a common issue with other CD47-targeted therapies. These candidates were in Phase 1b/2 clinical development across several indications, with a primary focus on hematological malignancies such as various types of leukemia, multiple myeloma, and lymphoma. The groundbreaking research that led to the development of TTI-621 began at UHN's Princess Margaret Cancer Centre and The Hospital for Sick Children (SickKids), stemming from a collaboration between Drs. John Dick, Jean Wang, and Jayne Danska.