Ipsen has gambled up to $610 million on a new class of bispecific T-cell engagers. The biobuck bet has landed the French drugmaker exclusive global rights to a preclinical Biomunex Pharmaceuticals prospect that engages a subset of cytotoxic T cells.
Biomunex is built on the idea that conventional bispecifics will struggle to treat solid tumors. The biotech has identified mucosal-associated invariant T cells (MAITs) as the solution. MAITs are a subset of T cells with potent cytotoxic capacity that are found in solid tumors. By engaging MAITs rather than activating all subsets of T cells, Biomunex is trying to avoid safety issues that limit doses of traditional bispecifics.
Ipsen sees promise in its compatriot’s ideas. The drugmaker has put together a package worth up to $610 million in upfront and milestone payments for global rights to the MAIT-cell engager BMX-502.
Biomunex has designed the drug candidate to selectively engage MAIT cells and target the GPC3 tumor antigen. GPC3 is highly expressed in multiple tumor types. Companies have thrown a range of modalities at the target. Roche began testing an anti-GPC3 antibody more than a decade ago. AstraZeneca started a phase 1/2 trial of a GPC3-directed CAR-T cell therapy about a year ago.
Other companies, including Roche subsidiary Chugai Pharmaceutical, have studied GPC3 bispecifics, but BMX-502 stands apart because of its focus on MAIT cells. Biomunex has generated evidence that zeroing in on MAIT cells could avoid the activation of regulatory T cells—and by extension the harmful cytokine release—seen in recipients of conventional T-cell engagers.
Minimizing cytokine release could improve the safety profile and extend the therapeutic window. Early evidence suggests MAIT engagers match the potency and efficacy of conventional bispecifics. The mix of equivalent efficacy and improved safety could enable Biomunex to select a dose that provides deep and durable responses without causing intolerable side effects.
That is the idea, anyway. Biomunex is still putting together the IND-enabling package for BMX-502 and, as such, is yet to validate the approach in the clinic. Ipsen will take responsibility for clinical validation. Once Biomunex has completed the IND package, Ipsen will take over for phase 1 preparations and all the subsequent steps on the path to market.
BMX-502 will slot into a preclinical pipeline that has been bolstered by deals this year. Ipsen has bet billions in biobucks to land rights to Marengo Therapeutics’ T-cell engagers along with antibody-drug conjugates from Sutro Biopharma and Foreseen Biotechnology. While cancer has been the focus, Ipsen also picked up an option on two of Skyhawk Therapeutics' neuroscience candidates.