Phase 1/2 Study of Ocaratuzumab, an Fc-Engineered Humanized Anti-CD20 Monoclonal Antibody, in Low-Affinity FcγRIIIa Patients with Previously Treated Follicular Lymphoma

This phase 2 study assessed the safety and efficacy of ocaratuzumab, a humanized anti-CD20 monoclonal antibody. Fifty patients with previously treated follicular lymphoma (FL) and a low-affi nity genotype of Fc gamma RIIIa received ocaratuzumab 375 mg/m 2 weekly for 4 weeks. Grade 3/4/5 adverse events (AEs) were reported in 11/1/1 patients, respectively. Serious AEs were reported by 11/50 patients, and three discontinued due to AEs. One patient died from aspiration pneumonia due to possibly drug-related nausea and vomiting. Investigatorassessed response rate was 30% (15/50), including four complete responses (CR), three CR unconfi rmed (CRu) and eight partial responses (PR). Investigator-assessed median Progression-free survivial (PFS) was 38.3 weeks. Ocaratuzumab's pharmacokinetic profi le was similar to that reported for rituximab. Lymphocyte subset analysis showed signifi cant, selective reduction of B-cells during and after ocaratuzumab treatment. Ocaratuzumab at this dose and schedule is active and well tolerated in patients with previously treated FL with low affinity Fc gamma RIIIa genotypes.