New isotype player enters after IGM's exit

The idea of developing anticancer antibodies using atypical immunoglobulin isotypes took a blow with IGM Biosciences' withdrawal from oncology a year ago, but it lives on through a merger of two private biotechs announced on Monday. Under the deal the UK's Epsilogen, whose focus is on the IgE isotype, is acquiring the US's TigaTx, which has an IgA-based project, for an undisclosed amount. Though the human immune system includes five immunoglobulin isotypes, each with distinct structural features, all currently developed antibody-based drugs use IgG, the most common one. But Epsilogen claims that each isotype has evolved to perform a specific function, and each cancer necessitates the selection of the most appropriate isotype for optimal results. Since the company already had expertise in IgG, in addition to its lead focus on IgE, the addition of TigaTx gives it three isotypes to work on. TigaTx secured up to $35.5m in NIH funding last December, and clearly thinks its chances of success in IgA will be increased by becoming part of a larger entity. Meanwhile, IGM Biosciences was once hoping to compete in lymphoma with the IgM-based anti-CD20 T-cell engager imvotamab, but is no longer active in oncology.

Selected MAb projects using specific immunoglobulin isotypes

Source: OncologyPipeline.