Phase I Multidose-Escalation Study of the Anti-CD19 Maytansinoid Immunoconjugate SAR3419 Administered by Intravenous Infusion Every 3 Weeks to Patients With Relapsed/Refractory B-Cell Lymphoma

Purpose We determine the maximum-tolerated dose (MTD), pharmacokinetics, safety, and preliminary efficacy of SAR3419, an antibody-drug conjugate targeting CD19, in a first-in-man phase I clinical trial in patients with relapsed lymphoma. Patients and Methods Patients with relapsed CD19+ B-cell lymphoma were treated with escalating doses of SAR3419 given by intravenous infusion once every 21 days. Results Thirty-nine patients were treated on seven dose levels ranging from 10 to 270 mg/m(2). The median number of prior treatment regimens was four (range, 1 to 9), and 11 patients had prior autologous or allogeneic stem-cell transplantation. The dose-limiting toxicities were reversible severe blurred vision associated with microcystic epithelial corneal changes reported in six patients and neuropathy in one patient. The MTD was 160 mg/m(2) once every 21 days. Hematologic and hepatic toxicities were predominantly grade 1 or 2 in severity. A total of 35 patients have completed at least two cycles of treatment and were evaluable for tumor response. Twenty-six patients (74%) demonstrated reduction in their tumor size; six of those patients achieved partial or complete remissions. Seven (47%) of 15 patients with rituximab-refractory disease demonstrated reduction in their tumor sizes. The pharmacokinetic profile of SAR3419 is characterized by linear kinetics, low clearance from 0.2 to 0.6 L/d/m(2), and an elimination half-life in the range of 3 to 7 days. Conclusion Using an every 3-week-schedule of SAR3419 for six cycles, the MTD is 160 mg/m(2). SAR3419 can be safely administered to patients with relapsed B-cell lymphoma and demonstrates promising clinical activity, including patients who were refractory to rituximab.