IGM Biosciences is a clinical-stage biotech that developed a platform for engineering IgM antibodies — a structural class of antibody with 10 binding domains versus 2 for conventional IgG antibodies, which IGM Biosciences argues gives them greater binding power and therapeutic potential. The company originally targeted both cancer and autoimmune diseases, but following two rapid restructurings in late 2024 and early 2025, IGM Biosciences halted its independent clinical programs, cut roughly 73% of its workforce, and is now exploring strategic alternatives. Its only active business is fulfilling obligations under a 2022 collaboration with Sanofi, under which IGM Biosciences conducts early-stage research and Phase 1 development on IgM antibodies targeting three immunology targets, after which Sanofi takes over all further development and commercialization. IGM Biosciences received a $150M upfront payment from Sanofi when the deal was signed, and is eligible for up to $1,065M per target in milestone payments, plus high single-digit to low-teen royalties on net sales of any approved products. The company has no active clinical trials of its own, generates no product revenue, and its path to any future cash depends entirely on Sanofi advancing the licensed candidates and on a potential sale, merger, or monetization of its IgM platform IP.