Regeneron Pharmaceuticals has reported encouraging results from the Phase I/II LINKER-MM1 clinical trial of its investigational bispecific antibody, linvoseltamab, in patients with relapsed/refractory multiple myeloma (r/r MM).

LINKER-MM1 is an open-label, multicentre, ongoing dose-escalation and dose-expansion trial that has enrolled 282 patients.

The completed Phase I dose-escalation part of the trial evaluated the tolerability, safety and dose-limiting toxicities across nine linvoseltamab dose levels, apart from various administration regimens.

The Phase II dose expansion segment is underway to analyse the safety and anti-tumour activity of linvoseltamab, with the primary endpoint being the objective response rate (ORR).

Key secondary endpoints comprise duration of response (DOR), progression-free survival (PFS), the rate of minimum residual disease (MRD) negative status, and overall survival (OS).

Findings after an 11-month median follow-up showed that the treatment with linvoseltamab offered a 71% ORR, with 46% of patients achieving a complete response (CR) or better.

The median time to response was one month, with the median time to a very good partial response (VGPR) or better being three months, and to a CR or better being eight months.

The median DoR, PFS, and OS were not reached at the time of reporting.

After 12 months, the estimated probability of maintaining a response was 78%, being progression-free was 69%, and survival was 75%.

Among patients who achieved a CR or better and were MRD evaluable, 93% were MRD negative at 10⁻⁵.

The trial also included a response-adapted regimen allowing patients to shift to every four-week dosing upon achieving a VGPR or better after at least 24 weeks of therapy.

Of the patients eligible for this extended dosing regimen, 90% were able to transition, and 48% of those who transitioned before achieving a CR experienced a deepening of response to CR or better.

Cytokine release syndrome (CRS) was the most common treatment-emergent adverse event, occurring in 46% of patients.

The latest development comes after the US Food and Drug Administration issued complete response letters for the company’s biologics license application for odronextamab in r/r follicular lymphoma and r/r diffuse large B-cell lymphoma.