ESMO: Bristol Myers drops Immatics' bispecific after $150M investment

Bristol Myers Squibb (BMS) has decided to discontinue its partnership with Immatics, leaving the latter in full control of the bispecific molecule IMA401. This molecule, which targets MAGEA4/8 on solid tumors and activates T cells, was acquired by BMS for $150 million upfront in late 2021. The deal also included $770 million in potential milestones, with the intention of collaborating on the development of IMA401. However, BMS made this decision before IMA401 entered the clinical stage. Now, as Immatics has shared initial phase 1 dose-escalation data, BMS has severed its ties to the candidate.

BMS attributed the termination of the co-development deal to its ongoing portfolio prioritization, a statement reinforced by recent updates from the pharmaceutical giant. Since Chris Boerner took over as CEO from Giovanni Caforio late last year, BMS has terminated several other deals. These include a TIGIT bispecific antibody deal with Agenus, a BCMA bispecific T-cell engager, and an antibody-drug conjugate returned to Eisai. Combined, BMS had paid $650 million upfront for the Agenus and Eisai candidates, and it reversed its decision on the BCMA prospect after filing to run a phase 3 trial.

Immatics disclosed BMS's decision to withdraw from another $150 million in upfront fees along with an early look at clinical data on IMA401. The presentation at the European Society for Medical Oncology (ESMO) Congress 2024 covered data from 35 patients with 16 different solid tumors. The patients, who were both HLA-A*02:01 and MAGEA4/8-positive, had previously undergone a median of four lines of systemic treatments. Immatics investigated IMA401 at nine escalating dose levels.

Out of the 29 evaluable patients for efficacy, Immatics reported four confirmed objective responses. Notably, all four responses were observed in patients who received at least 1 mg of IMA401 and had high MAGEA4/8 levels. This resulted in a 14% response rate in the overall efficacy population, which increased to 25% in the subgroup defined by higher levels of IMA401 and MAGEA4/8. The most common treatment-related adverse events were transient lymphopenia and mild to moderate cytokine release syndrome (CRS), usually occurring after the first dose. Earlier data included in the ESMO abstract mentioned up to grade 4 lymphopenia and only grade 1 and 2 CRS. Additionally, grade 3/4 neutropenia, a low level of white blood cells, did not reoccur after the introduction of dexamethasone.

Having already overseen the phase 1 trial, Immatics intends to continue the clinical development of IMA401. The biotech company has shifted from weekly to bi-weekly dosing based on clinical data and believes that a four-week dosing schedule may also be feasible. Immatics indicated that a four-week schedule would be optimal for potential combinations with checkpoint inhibitors. Updated data are expected to be available next year.