Abstract

7060 Background: IMM0306 is a fusion protein of CD20 monoclonal antibody with the CD47 binding domain of SIRPα on both heavy chains. It exerts excellent cancer killing efficacy by activating both macrophages and NK cells via blockade of CD47-SIRPα interaction and FcɣR engagement. Here, we report the safety, pharmacokinetics (PK), pharmacodynamics (PD), and efficacy results of phase I study in patients (pts) with relapsed or refractory (R/R) CD20-positive B-cell non-Hodgkin's lymphoma (B-NHL). Methods: Eligible pts with R/R CD20-positive B-NHL were enrolled in this multicenter phase I study (NCT05805943). IMM0306 was administered as monotherapy at escalating doses of 0.04, 0.1, 0.25, 0.5, 0.8, 1.2, 1.6, 2.0 mg/kg intravenously once a week until disease progression or intolerable toxicity. Dose-limiting toxicity (DLT) was evaluated in the first 28 days. Safety was evaluated per CTCAE 5.0, PK and PD analysis were also assessed, tumor assessments performed once every 8 weeks by Lugano 2014 criteria. Results: As of Nov 21, 2023, 48 pts were enrolled. The median age was 56 years with 30 (62.5%) males. The median prior lines of therapy were 2. All pts received previous anti-CD20 therapy. No DLTs were observed. Recommended phase II dose was determined as 2.0 mg/kg. The most frequent treatment related adverse events (TRAEs) were WBC decreased (66.7%), anemia (64.6%), lymphocyte decreased (58.3%), ANC decreased (47.9%), PLT decreased (45.8%), infusion-related reactions (35.4%). ≥grade 3 TRAEs occurred in 33 (68.8%) pts, with the most common being lymphocyte decreased (56.3%), WBC decreased (18.8%), ANC decreased (18.8%). 8 (16.7%) pts experienced treatment related serious adverse event. Discontinuation due to AEs occurred in 1 pt (grade 4 PLT decreased at 1.6mg/kg without bleeding). No AE led to death. IMM0306 exhibited approximate dose-proportional increase in PK exposure from 0.5 to 2.0 mg/kg and no obvious accumulation was observed after repeated dosing. At 1.2 mg/kg and higher dose, CD47 receptor occupancy on peripheral lymphocytes was saturated, suggesting IMM0306 is well tolerated from perspective of CD47 engagement. B-cell depleted rapidly at doses ≥ 0.8 mg/kg. Elevated cytokines levels were observed after first dosing of IMM0306, but multiple dosing did not stimulate further cytokine activation. Among 33 pts who received doses ≥ 0.8 mg/kg, 5 CR (4 follicular lymphoma [FL], 1 marginal zone lymphoma [MZL]), 5 PR (3 FL, 1 MZL, 1 diffuse large B cell lymphoma) and 11 SD were seen; the median PFS was 10.58 months (95% CI, 2.2, NA) and the median OS was not reached. Among 17 FL pts, 7 (41%) responded including 4 CR and 3 PR; among 6 MZL pts, 2 (33.3%) responded including 1 CR and 1 PR. Conclusions: IMM0306 was well-tolerated and with promising preliminary anti-tumor activity especially in pts with R/R FL and MZL. The phase Ⅱ study is ongoing. Clinical trial information: NCT05805943 .