Safety and efficacy of amulirafusp alfa (IMM0306), a fusion protein of CD20 monoclonal antibody with the CD47 binding domain of SIRPα, in patients with relapsed or refractory B-cell non-Hodgkin lymphoma: a phase 1/2 study.

Background: Amulirafusp alfa (IMM0306) is a fusion protein of CD47 binding domain of signal-regulatory protein alpha (SIRPα) with CD20 monoclonal antibody on both heavy chains. This study aimed to evaluate the safety and preliminary efficacy of amulirafusp alfa in relapsed or refractory (r/r) B-cell non-Hodgkin lymphoma (B-NHL).

Methods: We enrolled patients with CD20 + r/r B-NHL who had previously received at least two lines of therapy to receive a single-dose of amulirafusp alfa in the first 2 weeks, followed by a multiple-dose period, in which the patients received the same intravenous dose every week in 4-week cycles. The primary endpoints were to evaluate the safety, determine the maximum tolerated dose (MTD) and the recommended phase 2 dose (RP2D) of amulirafusp alfa.

Results: Between May 22, 2020 and February 10, 2022, 48 patients with r/r B-NHL were enrolled and received amulirafusp alfa at the doses of 40-2000 μg/kg. As of the data cut-off date of April 18, 2024, no dose-limiting toxicity was observed, and the MTD was not reached. The dose of 2000 μg/kg was identified as the RP2D. All grades and ≥ grade 3 treatment-related adverse events (TRAEs) occurred in 48 (100%) and 33 (68.8%) patients, respectively. The most common ≥ grade 3 TRAEs were lymphocyte count decreased (28/48, 58.3%), white blood cell count decreased (10/48, 20.8%), absolute neutrophil count decreased (9/48, 18.8%) and anemia (5/48, 10.4%). At the doses of 800-2000 μg/kg, objective response rate in follicular lymphoma and marginal zone lymphoma was 41.2% (7/17, 95% confidence interval [CI] 18.4-67.1) and 33.3% (2/6, 95% CI 3.7-71.0), respectively.

Conclusion: Amulirafusp alfa showed favorable safety profile and preliminary efficacy in patients with r/r B-NHL, meriting further investigation. Trial registration NCT05805943.