Phase I study of a novel humanized anti-CD20 antibody, BM-ca, in patients (pts) with relapsed or refractory indolent B-cell non-Hodgkin lymphoma (B-NHL) pretreated with rituximab.

Abstract

8551 Background: BM-ca is a novel humanized type-I/II anti-CD20 antibody, which is effective against rituximab-resistant cell line RC-K8, and has more potent anti-cell-proliferation activity than rituximab or ofatumumab when combined with cancer chemotherapeutics. The aim of this study was to evaluate the safety, efficacy, and PK profile of BM-ca in pts with indolent B-NHL. Methods: A total of 12 pts {age: median 61 (50-73), number of prior regimens: median 2 (1-13)} with indolent B-NHL relapsed after or refractory to rituximab-containing therapy underwent treatment by IV infusion of BM-ca weekly for 4 weeks at a dose of 5, 10, or 15 mg/kg. Initially, 3 pts were to undergo BM-ca therapy at a dose of 5 mg/kg using the conventional 3+3 dose escalation design. To minimize infusion reactions (IRs), pts were pretreated with acetaminophen and d-chlorpheniramine maleate. Allopurinol and/or hydrocortisone were also administered if necessary. Infusion was started at 50 or 100 mg/h and was gradually increased to a maximum of 400 mg/h. Since no DLTs were observed, all 12 pts completed weekly 4 doses of BM-ca. Results: The most frequent AE was IRs (11 of 12 pts), which occurred mostly in the first infusion, and the highest grade of AE was neutropenia (grade 4 in one pt of 15 mg/kg after the last infusion). Anti-BM-ca antibodies were not detected. Of the 12 pts examined, 2 achieved CR (10 mg/kg) and 2 PR (15 mg/kg); these 4 pts had follicular histology. The remaining 8 pts including one each of extranodal marginal zone, nodal marginal zone, and small lymphocytic histology were judged to achieve SD. The CR states in 2 pts continued at least >14 and >11 months, respectively. The PK properties of BM-ca were comparable to those of other naked anti-CD20 antibodies including rituximab (AUC and Cmax were proportional to the doses; Vdss≈4 L; t1/2≈750 h). Since at 10 mg/kg the response was the best and no grade 4 AE observed, 10 mg/kg was suggested as a recommended phase II dose. Conclusions: Four weekly IV administration of BM-ca up to 15 mg/kg was well tolerated and safe with promising preliminary anti-lymphoma activity in pts with indolent B-NHL. Further evaluation is warranted. Clinical trial information: 000004805.