Chimagen Biosciences builds multispecific antibodies meant to direct immune cells at diseased cells. GSK has agreed to buy full global rights to one of its preclinical programs for multiple myeloma, in a deal worth up to $750 million if development and commercial milestones are met. The upfront payment wasn’t disclosed, and the agreement still has to clear customary closing conditions.
The unnamed candidate is a trispecific T-cell engager: it is designed to bind a T cell and two tumor-associated antigens at the same time, bringing an immune cell into contact with a cancer cell. GSK will take over development and commercialization and expects to begin a Phase 1 trial in 2027. Chimagen and GSK haven’t identified the two tumor targets.
The attraction is also the risk. Existing T-cell engagers can produce strong responses in multiple myeloma, but BioSpace noted that the four approved bispecific antibodies in the class carry boxed warnings for cytokine release syndrome and neurologic toxicity. GSK says Chimagen’s two-antigen design is intended to improve both the durability of response and tolerability; those remain preclinical goals, not patient results.
Chimagen’s business is built around antibody-engineering platforms for multispecific T-cell and natural-killer-cell engagers in cancer and autoimmune disease. This transaction shows the handoff clearly: Chimagen creates a drug program, while a larger partner pays for rights and assumes the clinical-development and commercialization work. GSK is acquiring the program, not Chimagen itself.
It’s the partners’ second disclosed program sale. In 2024, GSK agreed to pay Chimagen $300 million upfront and as much as $550 million in milestones for CMG1A46, a separate engager aimed at CD19 and CD20. That drug has since entered Phase 1 testing for B-cell cancers and B-cell-driven autoimmune diseases, according to GSK.
The new deal is much less informative at signing: GSK disclosed a ceiling but not the upfront amount, the drug’s name or its targets. How much of the headline value depends on milestones cannot be determined without the upfront figure. The next public development step is the planned Phase 1 start in 2027.