The US Food and Drug Administration (FDA) has cleared IGM Biosciences’ two investigational new drug (IND) applications for initiating Phase Ib studies of imvotamab to treat both severe systemic lupus erythematosus (SLE) and severe rheumatoid arthritis (RA).

Imvotamab is an IgM-based CD20 X CD3 bispecific antibody T cell engager that has greater binding power to CD20-expressing cells when their levels are low.

Evaluating the tolerability, safety, pharmacodynamics, pharmacokinetics, and biologic activity of imvotamab in patients with severe RA and SLE is the primary outcome measure of both studies.

Patients selected for the trial did not respond to previous multiple therapies.

IGM Biosciences autoimmunity and inflammation president Mary Beth Harler said: “Treating autoimmune disease with T cell engagers is an exciting new field of therapeutic research, and we believe imvotamab, with its potential for deep B cell depletion, offers the opportunity to lead and transform treatment in this area.

“The data from our non-Hodgkin’s lymphoma clinical studies indicate that imvotamab can deplete CD20 expressing B cells, even rapidly growing lymphoma cells, with a favourable safety profile as compared with other T cell engaging CD20 x CD3 antibodies.

“Emerging data with cell-based therapies suggest that deep B cell depletion may have the potential to reset the immune system in patients with certain autoimmune diseases.”

The company intends to start enrolling patients for both multicentre clinical studies in the third quarter of this year.