Consolidation Anti-CD22 Fractionated Radioimmunotherapy with ⁹⁰y-Epratuzumab Tetraxetan Following R-CHOP in Elderly DLBCL Patients: A Lysa Phase II Prospective Trial

Consolidation using radioimmunotherapy (RIT) is a promising approach for elderly patients with diffuse large B-cell lymphoma (DLBCL) who are ineligible for autologous stem-cell transplantation. RIT using fractionated injections of ⁹⁰Y-epratuzumab tetraxetan (Immunomedics, Inc.), a radiolabeled humanized anti-CD22 antibody, has been evaluated in relapsed patients with indolent or aggressive non-Hodgkin lymphoma (NHL), providing long-term disease control with manageable hematologic toxicities (Morschhauser et al., J Clin Oncol. 2010;28(23);3709-16). A French phase II trial sponsored by the LYSA group now assessed front-line treatment using fractionated RIT with ⁹⁰Y-epratuzumab tetraxetan as consolidation therapy after R-CHOP in previously untreated elderly (age >60 years) patients presenting with stage I/II bulky or stage III/IV DLBCL.

The trial included 6 courses of R-CHOP delivered q2wks followed by 2 infusions of ⁹⁰Y-epratuzumab tetraxetan (2 × 15 mCi/m² [555 MBq/m²], 7 days apart), 8 wks later. Patients were enrolled at time of diagnosis.

From October 2008 to December 2010, 75 patients (41 males, 34 females) have been accrued prospectively at 19 French institutions. The median age was 69 (range, 60–79 years); 57 patients (76.0%) were Ann Arbor stage III/IV. Seventy-one of the 75 completed 6 courses of R-CHOP-14 and 61/75 (81.2%) were eligible for RIT. Thus, 14 patients were considered ineligible for RIT because of R-CHOP toxicity (N= 5), progressive disease (PD, N=3), patient refusal (N=3), or concomitant illness (N=3). RIT toxicity consisted of grade 3–4 hematologic toxicity in 51/61 patients (83.6%): grade 3–4 neutropenia in 46 (75.4%), grade 3–4 anemia in 15 (24.6%), and grade 3–4 thrombocytopenia in 47 (77.0%), with a nadir at 42, 48, and 43 days after RIT and a median duration of 18, 5, and 17 days, respectively. Following RIT, RBC and/or platelet transfusions were given to 31 patients (50.8 %). Serious febrile neutropenia was observed in 13 cases (17.3 %) after R-CHOP and in 3 patients (4.9%) following RIT. RIT's severe non-hematologic toxicity consisted of grade 4 gastrointestinal in 1 patient (1.6 %) and grade 4 infection in 3 (4.9%). No patient had mucositis after RIT. In the follow-up, 2 patients (2.6%) developed myelodysplastic syndrome 5 and 20 months after RIT.

Using the 1999 International Workshop for Response Criteria for NHL (Cheson 1999), the overall response rate (ORR) after 6 × R-CHOP14 was 94.6% (71/75); 52 patients (69.3%) achieved CR/CRu and 19 (25.3%) had a partial response (PR). Among the 4 remaining patients, one had stable disease and 2 had PD; no assessment was obtained in the other. In an intention-to-treat analysis, CR/CRu rate after 6 × R-CHOP14 followed by RIT was 72.0% (N=54). Seven patients (9.3%) remained in PR and 8 (10.7%) progressed (2 patients previously in PR with PET-positive findings, 3 previously in CRu, including 1 PET-positive, and 3 in PD before RIT and then ineligible for RIT). No response assessment was obtained in the 6 others ineligible for RIT. At a median follow-up of 24 months (range, 1–46), 18 patients experienced lymphoma progression and/or a related death, yielding an estimated 2-year event-free-survival (EFS) of 73.3% (60.7-82.5%) and an estimated 2-year overall survival (OS) of 83.2% (71.4-90.4%). For the 61 patients who received 6 courses of R-CHOP followed by RIT consolidation, ORR was 91.8% (56/61); 50 patients (81.9%) achieved CR/CRu. Eight of 16 patients (50.0%) who had less than a CR/CRu with R-CHOP converted to CR/CRu after RIT. According to a PET analysis (Cheson 2007; N=55), 12 of the 24 patients (50.0%) who were not PET-negative after R-CHOP improved their metabolic response after RIT, resulting in a CR rate of 72.7%. Among these 61 patients, 12 experienced progression and/or a related death, yielding an estimated 2-year EFS of 78.7% (65.1–87.4%) and an estimated 2–year OS of 90.1% (77.7–95.8%).

This phase II study clearly shows that fractionated RIT with ⁹⁰Y-epratuzumab as a consolidation therapy after 6 × R-CHOP-14 is feasible and tolerable in elderly untreated DLBCL patients with advanced disease. RIT markedly improved response status observed after 6 × R-CHOP14. EFS data achieved with R-CHOP plus RIT compare favourably with those achieved with R-CHOP alone in the same patient population.

Wegener:Immunomedics: Employment. Goldenberg:Immunomedics: Employment, Equity Ownership.