Pilot Study of Lenalidomide-Rituximab Combination in Relapsed/Refractory Diffuse Large B Cell Lymphoma

Abstract 3695

Despite recent immunochemotherapy advances approximately 50% of DLBCL patients relapse. Data emerging from initial clinical trials demonstrated that Lenalidomide has a significant activity against different subtypes of relapsed/refractory aggressive B-cell lymphoma. Clinical responses are histology subtype-dependent and most prominent in mantle cell lymphoma. The results in DLBCL were less encouraging with ORR of 26%, CR of 9%, PFS of 2.7 mo. Concurrently targeting the tumor cell itself with monoclonal antibody and targeting the immune response and microenvironment with Lenalidomide may be a promising therapeutic strategy. Encouraging by our initial results of Lenalidomide-Rituximab (LR) combination in patient with refractory (R/R) DLBCL (Ivanov V. et al., 2010), Institutional Multidisciplinary Meeting proposed this combination for 17 patients with R/R DLBCL. All pts were refractory to three or more (range: 2–5) previous lines of conventional immuno-chemotherapy. All eligible pts, except 4 primary-refractory, were previously autografted. Median age for the whole group was 62,5 years, (range: 43–79), 5 pts are female. 65% of patients were younger than 65 y. Patients received combination of Rituximab 375 mg/m2 on day 1 or day 7; Lenalidomide (Revlimid), 15 mg/d for the first pt and 25 mg/d for other 16 pts, for 21/28 days. Dexamethasone 40mg, day 1–4 was given for first 7 pts. Initial decision on adding Dexamethasone was based on the extrapolation from the recommended regimen used in multiple myeloma, but it was abandoned in last 10 pts. Initially the treatment duration was established for 6 months, but it was prolonged to 7–11 months for patients in CR.

Of 17 pts enrolled on study, 3 patients stopped the treatment during the first course: 1 pt because of grade 3 toxicity and 2 pts because of explosive disease progression. Both patients were switched to palliative care. In 14 pts, received more than 1 course of treatment, 7 (50 %) responded to LR combination, including 6 pts (43%) with CR and 1 (7%) patient with PR. One pt with clinical and PET-FDG scan improvement after 3 courses of LR was included into “auto-allo” tandem program and actually in CR at +12 months after PBSCT. Six pts progressed on LR treatment and were switched to palliative regimens. In intention to treat analysis the CR rate for the whole group was 35%. As regards the follow-up, all 7 pts in PR and CR are evaluable for evaluation. The patient in PR progressed after 5 courses of LR. Six patients in CR group received an average of 8 (range: 7–11) courses of LR treatment. Two patients relapsed after 5 and 26 months of CR and other 4 patients are actually in CR at +7, +17, +18 and +24 months. Adverse events were manageable and the most common toxicity included thrombocytopenia and neutropenia.

In relapsed/refractory DLBCL modest initial results of Lenalidomide monotherapy emerge the use of new effective combinations. Recently the combination Lenalidomide-Rituximab (LR) was shown to be highly efficacious in phase 2 study in elderly (>65 y.o.) patients with DLBCL (Zinzani et al., 2011). Into the group of 23 pts the ORR rate at the end of 6-months induction phase was 35%. Our data confirm results of Bologna group in the younger group of patients. Given the poor prognosis of refractory DLBCL, enrolment in already running prospective clinical trials with Lenalidomide are underway and the investigation of the combination of Lenalidomide and Rituximab is further warranted.