Correlative Analysis and Clinical Update Of a Phase II Study Using Lenalidomide and Rituximab In Patients With Indolent Non-Hodgkin Lymphoma

Background Although indolent non-Hodgkin lymphomas (iNHLs) are responsive to initial therapy, patients have a relapsing and progressive disease course and most remain incurable with current treatments. Lenalidomide is an immunomodulatory agent that enhances rituximab-mediated antibody-dependent cellular cytotoxicity. In lymphoma cell lines, animal models, and in several phase II trials, combining lenalidomide and rituximab (R2) resulted in improved antitumor activity relative to either agent alone. However, the immunological mechanisms remain unclear. Here we provide updated results from a phase II trial investigating the clinical activity of R2 in previously untreated and relapsed/refractory (R/R) patients with iNHL. We also present an analysis of immunologic correlative data that may provide insight into the therapy's mechanism-of-action and may also predict response. Aims Study aims were to assess: the clinical activity of the R2 regimen in previously untreated and R/R iNHL patients and, assess the potential of serum cytokine levels to predict response. Methods Patients had previously untreated (n=15) or R/R (n=30) iNHL with measurable disease, and ECOG Performance Status ² 2. Lenalidomide (20 mg/day) was administered on days 1–21 of a 28-day cycle and continued until disease progression, rituximab 375 mg/m2 IV was administered on day 15 of cycle 1 and repeated weekly for a total of 4 doses. The primary clinical endpoint was overall response rate (ORR). Secondary endpoints included response duration (DR), overall survival, progression-free survival (PFS), and safety. The correlative serum cytokine samples were obtained from patients at baseline, D15 (prior to treatment with rituximab), D30 and D60. IL-1, 2, 6, 8, 10, 12, GM-CSF, IFN-γ, TNF-α , CXCL-10/IP-10 levels were measured at each time point using a Meso Scale Discovery multi-plex cytokine assay. The cytokine levels at each time point were then correlated with response using a two-sided T test. Results Of the 30 R/R patients, 22 had follicular lymphoma (FL), the median age was 60 years, median number of prior therapies was 3 (range 1–11), and 50% were refractory to rituximab. Of the 15 previously untreated patients, 12 had FL and the median age was 58. For the 27 evaluable R/R patients, the ORR was 74%, including 12 patients (44%) with a CR. At a median follow-up of 34 months, median PFS was 12.4 months, the median DR and time to next therapy (TTNT) were 15.4 and 37.4 months respectively with 7 remissions that are ongoing including three that have lasted more than 48 months. Of the 15 previously untreated patients 13 are evaluable for response; the ORR was 92% with 6 of 13 (42%) having a CR. At a median follow-up of 18 months the median PFS is 14.5 months; the median DR has not been reached. The correlative analyses showed that there was a significant increase in IFN-γ, GM-CSF, CXCL-10 and IL-2 at Day 15 with a 652, 494, 737, and 242% increase respectively above baseline which correlated with patients who had a CR (p < 0.05), Table. IL-1, 6, 8, 10, 12, and TNF-α were also measured, but did not predict CR at any time point. Phenotypic and functional analyses are ongoing. There was no significant difference in the percent increase in cytokine levels in previously untreated versus R/R patients. Conclusion The R2 regimen has considerable activity in patients with both untreated or R/R iNHL, particularly those with FL. A significant increase in the serum levels of IFN-γ, GM-CSF, IL-2 and CXCL-10/IP-10 after 2 weeks of lenalidomide alone correlates with achievement of CR. Disclosures: Off Label Use: The use of lenalidomide for the treatment of indolent NHL will be discussed which is not an FDA approved indication. Tuscano:Celgene: Honoraria, Research Funding.