A big week for biotechs and bispecifics

It’s been a busy few days for companies developing the dual-action treatments called bispecific antibodies.

Bristol Myers Squibb bought the rights to Agenus’ bispecific candidate AGEN1777 for $200 million. Soteria Biotherapeutics launched with $42 million in series A financing. And Compass Therapeutics agreed to merge with TRIGR Therapeutics.

Bispecific antibodies are typically designed to bind to two targets, one on a cancer cell and one on an immune cell, with the goal of getting the immune cell to kill the cancer cell. But building a safe and effective bispecific antibody is challenging. The antibody needs to be able to activate immune cells—but not so much that it causes side effects such as cytokine release syndrome.

According to BMS, AGEN1777 blocks TIGIT, a molecule on the surface of immune cells that can defuse their cancer-killing activity. By blocking TIGIT, AGEN1777 may serve as a checkpoint inhibitor, an immunotherapy that revs up the immune system’s antitumor activity.

Soteria’s technology is called T-LITE. The company describes its bispecific antibody candidates as inactive in the human body until a person receives a small-molecule drug. That drug activates the antibodies, allowing for shorter dosing and potentially lower side effects. The funding is led by Roche Venture Fund and 5AM Ventures.

The antibody at the center of the Compass-TRIGR merger is CTX-009, which the companies say is in Phase 1 trials in South Korea in people with cancer. CTX-009 is a bispecific that inhibits two molecules called DLL4 and VEGF-A. A similar antibody from Mereo BioPharma seems to stop tumor growth. The Mereo antibody also seems to reduce the number of cancer stem cells that can give rise to tumors.