Initial Results from an International Study in Relapsed/Refractory Aggressive Non-Hodgkin’s Lymphoma To Confirm the Activity, Safety and Criteria for Predicting Response to Lenalidomide Monotherapy.

Background: Lenalidomide (Revlimid®) has demonstrated activity with manageable side effects in relapsed/refractory aggressive non-Hodgkin’s lymphoma (NHL). In the initial pilot study, response to lenalidomide was associated with low tumor burden, long duration from prior rituximab and high absolute lymphocyte count.

Aims:

1. To confirm the activity and safety of lenalidomide monotherapy in patients with relapsed/refractory aggressive NHL in an international setting and

2. Determine whether predictors of response identified in the previous study were valid.

Methods: Patients with relapsed/refractory aggressive NHL with measurable disease ≥ 2 cm after at least 1 prior treatment regimen were eligible. Patients received 25 mg lenalidomide orally once daily on Days 1–21 every 28 days and continued therapy as tolerated or until disease progression. Response and progression were evaluated using the IWLRC methodology. Univariate analyses using Fisher’s exact test were conducted to investigate and characterize associations of prognostic variables with response.

Results: Eighteen patients who received lenalidomide were eligible for response assessment as of May 15, 2007. The median age was 66 (43–81) and 17 were male. Histology was diffuse large B-cell lymphoma [DLBCL] (n=11), mantle cell lymphoma [MCL] (n=5) and transformed (n=2). Median time from diagnosis was 2 (0.4–12) years and median number of prior treatment regimens was 3 (1–13). Four patients (22%) exhibited an objective partial response including 2/11(18%) DLBCL and 2/5 (40%) MCL. Five patients had stable disease. Lenalidomide response was associated with low disease burden (29% for < 50 cm²v 0% for ≥ 50 cm²), time from last rituximab to lenalidomide treatment (36% for ≥ 230 days v 0% for < 230 days) and absolute lymphocyte count [ALC] (33% for ≥ 0.6×10⁹/L v 0% < 0.6×10⁹/L). Patients with favorable values for these three prognostic factors (N = 7) had a 57% response rate (compared with a 0% response rate for patients with unfavorable values (N = 11; P = 0.01). Grade 4 adverse events were neutropenia (22%) and thrombocytopenia (11%). Most common Grade 3 adverse events were fatigue (17%), thrombocytopenia (11%) and leukopenia (11%).

Conclusion: Lenalidomide has activity in relapsed/refractory aggressive NHL with a favorable safety profile. Initial results from this ongoing study are confirming that patients with low tumor burden, long duration from prior rituximab, and high ALC are more likely to respond.