Background: MOR202, a HuCAL-derived, human IgG1 CD38 monoclonal antibody induces ADCC and ADCP as effector functions; preclinical models show high activity of single-agent MOR202 and synergy in combination with immunomodulatory drugs (IMiDs), lenalidomide (LEN) or pomalidomide (POM). Unlike other CD38 antibodies, MOR202 does not induce complement-dependent cytotoxicity thought to be a major contributor to infusion-related reactions (IRRs). Methods: This is aninterim analysis of a multicenter, dose-escalation phase I/IIa study of MOR202 in relapsed or refractory multiple myeloma (MM). Preliminarysafety and efficacy data from 3 cohorts of patients (pts) treated with MOR202 alone or with an IMiD are presented: MOR202 4, 8 and 16 mg/kg weekly; MOR202 8 or 16 mg/kg weekly with either LEN or POM. Primary objectives were to evaluate the safety, maximum tolerated dose (MTD)/recommended phase II dose of MOR202. Results: As of November 23, 17 pts were treated. Pts receiving MOR202 alone or with POM were relapsed/refractory to prior bortezomib and LEN with a median of 4 and 3 prior regimens respectively. Pts given MOR202 + LEN had a median of 2 prior regimens, mainly bortezomib, cyclophosphamide and autologous stem cell transplant. The MTD has not been reached. MOR202 alone or with an IMiD was well tolerated with mainly hematological toxicity. No MOR202-related study discontinuations or deaths were recorded. A 2-hour MOR202 infusion was feasible in all pts. IRRs (grade 1) were seen in only 1/17 pts. Responses were reported in 6/15 evaluable pts: 2 very good partial responses (VGPR) and 4 partial responses (PR) with 5/6 still ongoing. The longest duration of response was > 10 months in a pt given MOR202 alone; all 9 pts receiving MOR202 alone derived clinical benefit (1 VGPR, 2 PR and 6 stable disease). Preservation of high CD38 levels on MM cells under MOR202 therapy was shown. Conclusions: In this analysis, MOR202 given as a 2-hour infusion showed excellent infusion tolerability and overall safety profile. Promising preliminary efficacy and long-lasting tumor control was seen for MOR202 +/- IMiDs. Clinical trial information: NCT01421186