Efficacy of the oral mTORC1 inhibitor everolimus in relapsed or refractory indolent lymphoma

Relapsed indolent lymphoma often becomes refractory to standard chemoimmunotherapy and requires new therapeutic strategies. Targeting the PI3K/mTOR pathway in several types of lymphoma has shown preclinical and clinical efficacy providing the rationale to test this strategy in the treatment of relapsed/refractory indolent lymphomas. We investigated in a phase II open label clinical trial the efficacy and safety of single agent everolimus, an inhibitor of mTORC1, in patients with relapsed/refractory indolent lymphomas. Eligible patients received oral everolimus 10 mg daily on a 28 day-cycle schedule. The primary endpoint was to evaluate the overall response rate (ORR) and safety of single-agent everolimus in this patient population. Fifty-five patients with indolent lymphoma were accrued. The median age was 67 years (range: 33-85) with a median of five prior therapies (range: 1-10). The ORR was 35% (19/55; 95% CI: 24-48%), with complete response unconfirmed in 4% (2/55), and partial response in 31% (17/55). The ORR was 61% (14/23) in the patients with FL. The median time to response was 2.3 months (range: 1.4-14.1), median duration of response of 11.5 months (95%-CI: 5.7-30.4), and a median progression-free survival of 7.2 months (95%-CI: 5.5-12.5). The most common toxicity was hematologic with grades 3-4 anemia, neutropenia, and thrombocytopenia documented in 15% (8/55), 22% (12/55), and 33% (18/55), respectively. There were no cases of febrile neutropenia, and eight patients discontinued therapy because of adverse events. Everolimus monotherapy is a valid therapeutic option in the relapsed and/or refractory indolent non-Hodgkin lymphoma patients and is well tolerated.