Consolidation Anti-CD22 Fractionated Radioimmunotherapy with 90Y Epratuzumab Tetraxetan Following R-CHOP In Elderly DLBCL Patients

Radioimmunotherapy (RIT) is under study as a consolidation treatment after chemotherapy induction in follicular lymphoma patients. This approach also appears interesting in diffuse large B-cell lymphoma (DLBCL) patients >60 years, who are not candidates for bone marrow transplantation. ⁹⁰Y-epratuzumab tetraxetan (Immunomedics, Inc.) is a radiolabeled humanized anti-CD22 antibody that has been used for a fractionated RIT, showing high rates of durable complete responses with manageable hematologic toxicity in previously-treated indolent and aggressive non-Hodgkin lymphoma (NHL) patients (Morschhauser et al., J Clin Oncol. 2010;28(23);3709-16). A French phase II trial sponsored by the GOELAMS group is ongoing, assessing fractionated RIT using ⁹⁰Y-epratuzumab tetraxetan as a consolidation therapy after first-line chemotherapy in disseminated DLBCL patients >60 years. The protocol has been designed to include 75 patients; 64 patients have been already enrolled. We report the initial results, in particular safety data, on the first 29 available patients.

From October 2008 to November 2009, 29 untreated DLCBL patients >60 years were studied in several French institutions with an initial course of six cycles of R-CHOP14 followed 8 weeks later by two weekly infusions of ⁹⁰Y-epratuzumab tetraxetan (15 mCi/m² [555 MBq/m²]) 7 days apart. Hematologic and non-hematologic toxicities were evaluated using NCI-CTC v.3.0. Treatment responses were classified according to the 1999 International Workshop for Response Criteria for NHL.

Twenty-six patients underwent the entire course of R-CHOP and 23 received the 2 weekly RIT injections. Following R-CHOP, grade 3–4 neutropenia was observed in 20 patients (68.9%) and grade 3–4 thrombocytopenia in 4 (13.7%). During RIT infusions, 4 patients showed transient change of pulse or blood pressure, with 2 attributed to vasovagal reactions. RIT toxicity included grade 3–4 hematologic toxicity in 18 of 23 patients (78.3%); the most common grade > 3 toxicities were neutropenia (N=18, 78.3%) and thrombocytopenia (N=17, 73.9%). Serious febrile neutropenia was observed in 4 cases (13.8%) after R-CHOP and in 2 patients (8.7%) following RIT. Compared to R-CHOP, RIT non-hematologic toxicity was uncommon; moderate or severe gastrointestinal toxicity was observed in 10 patients (34.5%) after R-CHOP and in 2 (8.7%) following RIT; moderate or severe infection in 9 patients (31.0%) after R-CHOP and in 1 (4.3%) after RIT; and moderate or severe mucositis in 10 (34.4%) patients following R-CHOP, while no patient had mucositis after RIT. Following RIT, red cells and/or platelets transfusions were given to 12 patients (52,2%). Following R-CHOP, 10 of the 25 patients (40.0%) achieved a complete response (CR) or unconfirmed CR (CRu), 13 patients (52.0%) had a partial response (PR) and 2 patients (8.0%) had a stable disease. Six weeks after RIT, 13 patients (56.5%) achieved a CR or CRu, 9 patients (39.1%) had PRs, and 1 patient (4.3%) had progressive disease. Four of 13 patients (30.7%) who achieved less than a CR or CRu with R-CHOP improved their remission status 6 weeks after RIT.

These preliminary results indicate the feasibility and safety of fractionated RIT with ⁹⁰Y-epratuzumab as a consolidation therapy for elderly DLBCL patients. Additional data will be presented at the time of the communication.

Off Label Use: monoclonal antibody epratuzumab labeled with yttrium 90 in phase II clinical trial. Wegener:Immunomedics, Inc.: Employment, shareholders. Goldenberg:Immunomedics, Inc.: Employment, shareholders.