Phase 1 trial of durvalumab (anti-PD-L1) in combination with lenalidomide in relapsed/refractory cutaneous T cell lymphoma

T cells in cutaneous T-cell lymphoma (CTCL) are functionally exhausted, expressing immune inhibitory molecules such as PD1 and PD-L1. Durvalumab selectively targets PD-L1 on exhausted T cells and distinct cells within the CTCL tumor microenvironment (TME) and may restore an anti-tumor immune response. The oral immunomodulator lenalidomide, which has shown activity in CTCL, may enhance immune checkpoint blockade by durvalumab. We initiated a phase 1/2 clinical trial of lenalidomide and durvalumab in patients with refractory/advanced CTCL (NCT03011814). Primary objectives were to assess safety and tolerability and identify the maximum tolerated dose/recommended phase 2 dose. Secondary and tertiary objectives were to investigate efficacy and the effects on the TME. Thirteen patients enrolled in sequential cohorts received fixed dose durvalumab and dose escalation of lenalidomide. Thirteen patients were evaluable for toxicities and 12 for response in phase 1. No serious adverse events (AEs) or dose-limiting toxicities (DLTs) were observed during cycles 1-3 (DLT evaluation period). The most frequent AEs were tumor flare, fatigue, neutropenia and leukopenia. Three patients developed grade 1/2 autoimmune thyroiditis that resolved with treatment. Median cycles of treatment were 11 (range, 3-42+). Median duration of response was 25.5 (range 8-36.5) months. Anti-PD-L1/lenalidomide showed clinical activity; there were 7 partial responses, 4 stable disease and 1 progressive disease. Adaptive and innate immune signatures potentially predictive of response seen in gene expression profiling of serial skin samples were downregulation of TNF-alpha signaling via NFκB, IFN-gamma, and PI3-AKT-mTOR signaling pathways in responders vs up-regulation of MYC targets and pro-inflammatory pathways in non-responders. Profiling of immune cell compositions revealed changes in individual immune cell clusters based on treatment status and response.