PURPOSE To assess the efficacy of pembrolizumab in patients with advanced relapsed or refractory mycosis fungoides (MF) or Sézary syndrome (SS). PATIENTS AND METHODS CITN-10 is a single-arm, multicenter phase II trial of 24 patients with advanced MF or SS. Patients were treated with pembrolizumab 2 mg/kg every 3 weeks for up to 24 months. The primary end point was overall response rate by consensus global response criteria. RESULTS Patients had advanced-stage disease (23 of 24 with stage IIB to IV MF/SS) and were heavily pretreated with a median of four prior systemic therapies. The overall response rate was 38% with two complete responses and seven partial responses. Of the nine responding patients, six had 90% or more improvement in skin disease by modified Severity Weighted Assessment Tool, and eight had ongoing responses at last follow-up. The median duration of response was not reached, with a median response follow-up time of 58 weeks. Immune-related adverse events led to treatment discontinuation in four patients. A transient worsening of erythroderma and pruritus occurred in 53% of patients with SS. This cutaneous flare reaction did not result in treatment discontinuation for any patient. The flare reaction correlated with high PD-1 expression on Sézary cells but did not associate with subsequent clinical responses or lack of response. Treatment responses did not correlate with expression of PD-L1, total mutation burden, or an interferon-γ gene expression signature. CONCLUSION Pembrolizumab demonstrated significant antitumor activity with durable responses and a favorable safety profile in patients with advanced MF/SS.

BackgroundWhile immune checkpoint blockade has greatly improved clinical outcomes in diseases such as melanoma, there remains a need for predictive biomarkers to determine who will likely benefit most from which therapy. To date, most biomarkers of response have been identified in the tumors themselves. Biomarkers that could be assessed from peripheral blood would be even more desirable, because of ease of access and reproducibility of sampling.MethodsWe used mass cytometry (CyTOF) to comprehensively profile peripheral blood of melanoma patients, in order to find predictive biomarkers of response to anti-CTLA-4 or anti-PD-1 therapy. Using a panel of ~ 40 surface and intracellular markers, we performed in-depth phenotypic and functional immune profiling to identify potential predictive biomarker candidates.ResultsImmune profiling of baseline peripheral blood samples using CyTOF revealed that anti-CTLA-4 and anti-PD-1 therapies have distinct sets of candidate biomarkers. The distribution of CD4+ and CD8+ memory/non-memory cells and other memory subsets was different between responders and non-responders to anti-CTLA-4 therapy. In anti-PD-1 (but not anti-CTLA-4) treated patients, we discovered differences in CD69 and MIP-1β expressing NK cells between responders and non-responders. Finally, multivariate analysis was used to develop a model for the prediction of response.ConclusionsOur results indicate that anti-CTLA-4 and anti-PD-1 have distinct predictive biomarker candidates. CD4+ and CD8+ memory T cell subsets play an important role in response to anti-CTLA-4, and are potential biomarker candidates. For anti-PD-1 therapy, NK cell subsets (but not memory T cell subsets) correlated with clinical response to therapy. These functionally active NK cell subsets likely play a critical role in the anti-tumor response triggered by anti-PD-1.Electronic supplementary materialThe online version of this article (10.1186/s40425-018-0328-8) contains supplementary material, which is available to authorized users.

Purpose Local radiation therapy (RT) in combination with systemic anti-CTLA-4 immunotherapy may enhance induction of systemic anti-melanoma immune responses. The primary objective of this trial was to assess the safety and efficacy of combining ipilimumab with RT in patients with stage IV melanoma. Secondary objectives included laboratory assessment of induction of anti-melanoma immune responses. Materials/Methods In our prospective clinical trial, 22 patients with stage IV melanoma were treated with palliative RT and ipilimumab for 4 cycles. RT to 1-2 disease sites was initiated within 5 days after starting ipilimumab. Patients had ≥1 nonirradiated metastasis measuring 7≥1.5 cm for response assessment. Tumor imaging studies were obtained at baseline, 2-4 weeks following cycle 4 of ipilimumab, and every 3 months until progression. Laboratory immune response parameters were measured before and during treatment. Results Combination therapy was well-tolerated without unexpected toxicities. Eleven patients (50.0%) had clinical benefit from therapy, including complete and partial responses (CR, PR) and stable disease (SD) at median follow-up of 55 weeks. Three (27.3%) achieved an ongoing systemic CR at median follow-up of 55 weeks (range 32-65), and 3 (27.3%) had initial PR for a median of 40 weeks. Analysis of immune response data suggests a relationship between elevated CD8-activated T-cells and response. Conclusion This is the second prospective clinical trial of treatment of metastatic melanoma with the combination of RT and systemic immunotherapy and the first using this sequence of therapy. Results from this trial demonstrate that a subset of patients can benefit from combination therapy, arguing for continued clinical investigation into the use of radiation therapy in combination with immunotherapy including PD-1 inhibitors, which may have the potential to be even more effective in combination with radiation.

Background:PD-1 and PD-L1/PD-L2 are expressed by malignant T-cells in mycosis fungoides (MF) and Sézary syndrome (SS). PD-1 is additionally expressed by tumor-infiltrating cytotoxic T-cells and PD-L1 is expressed by macrophages and other stromal components of the tumor microenvironment in these diseases. Moreover, reports of 9p24.1/PD-L2 translocation and CTLA4-CD28 fusion events in MF/SS support a genomic basis for immune evasion. Here, we explore the clinical activity of pembrolizumab, an immune checkpoint inhibitor of the PD-1/PD-L1 axis, in MF/SS. Methods:Patients (pts) with MF/SS stages IB-IV treated with at least 1 prior systemic therapy were enrolled in this phase 2, single-arm study coordinated by the Cancer Immunotherapy Trials Network (CITN). A Simon two-stage design was applied where stage 2 is initiated if 1 of 9 pts had an objective response. An additional 15 pts were planned in stage 2. Pembrolizumab was administered at 2 mg/kg every 3 weeks and treatment was allowed up to 2 years. The primary endpoint was overall response rate (ORR) as determined by the consensus global response criteria. Secondary endpoints were safety/tolerability, time to response (TTR), duration of response (DOR) and progression-free survival (PFS). Correlative biomarker studies included immunohistochemistry (IHC) staining for PD-L1, PD-L2, and multiple immune subsets as well as serum analysis of 62 cytokines and chemokines. Phenotypic and functional profiling of malignant and non-malignant immune cells will be performed by flow cytometry and mass cytometry (CyTOF). Results: The study completed enrollment and all 24 patients received at least one dose of pembrolizumab. Median age was 67 (range 44-85); 18 were male. Patients were advanced stage with 23 patients (96%) stage IIB or higher, including 15 patients (63%) with stage IVA SS. Most pts were heavily treated with a median of 4 prior systemic therapies (range 1-11). The median follow-up time was 40 weeks (range 9-60 weeks). The objective response rate (ORR) was 38% with 1 complete response (CR) and 8 partial responses (PR). Of the responding pts, 6 pts had 90% or greater improvement in skin disease as measured by mSWAT. An additional 9 pts (38%) had stable disease (SD). The median TTR was 11 weeks (range 8-41 weeks). Responses were durable with 8 of 9 (89%) responses currently ongoing at a median of 32 weeks of duration (4-46). The median PFS has not yet been reached, and the one-year PFS was 69%. There was no significant association between response and clinical characteristics including stage, disease type (MF vs. SS), and number of prior therapies, nor with skin tissue expression of PD-1, PD-L1, PD-L2, or infiltrating CD8+ T-cells as determined by IHC. Planned additional correlatives including CyTOF profiling, gene expression profiling, T cell receptor high throughput sequencing, multiplexed ion beam imaging (MIBI), and whole exome sequencing will explore potential predictive biomarkers of response. Adverse events (AE) were consistent with those seen in prior studies of pembrolizumab with the exception of an immune-mediated skin flare reaction seen in 6 pts (2 grade 2 and 4 grade 3). Skin flares occurred exclusively in patients with SS (6/15; 40%) and were associated with lower serum levels of the cytokines IL-7 and SCF prior to pembrolizumab treatment (p=0.01 and p=0.02 respectively, n.s. by Bonferroni correction). Pts with the skin flare reaction experienced increases in serum IFN-gamma, IL-12p40, IL-15, LIF, G-CSF, and CCL4 following treatment. There were two treatment related serious adverse events (SAE), both immune related. One pt experienced grade 2 pneumonitis which resolved with systemic corticosteroids. Another patient experienced grade 3 diarrhea secondary to steroid-refractory duodenitis. Conclusions: Pembrolizumab has significant clinical activity in pts with previously treated MF/SS. Responses were durable and were not associated with any identifiable clinical or pathologic characteristics. Treatment was well tolerated with a toxicity profile consistent with prior pembrolizumab studies, though 40% of pts with SS developed a notable skin flare reaction. These findings support further study of PD-1 blockade in the treatment of MF and SS. A phase 2 trial of pembrolizumab in combination with interferon-gamma is being developed based on these results. Disclosures Porcu: Millenium: Other: investigator in a clinical trial; miRagen: Other: Investigator in a clinical trial; celgene: Other: Investigator in a clinical trial; Innate Pharma: Other: Investigator in a clinical trial. Foss:Celgene: Consultancy, Research Funding, Speakers Bureau; Eisai: Consultancy; Seattle Genetics: Consultancy, Speakers Bureau; Spectrum Pharmaceuticals: Consultancy. Moskowitz:Bristol Myers Squibb: Honoraria; Merck: Honoraria; Seattle Genetics: Honoraria, Research Funding. Sokol:Seattle Genetics: Consultancy; Spectrum: Consultancy. Yearley:Merck: Employment. Chartash:Merck: Employment. Townson:Merck: Employment. Horwitz:Spectrum: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy; Huya: Consultancy; Infinity: Consultancy, Research Funding; Kyowa Hakka Kirin: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Celgene: Consultancy; ADCT Therapeutics: Research Funding. Kim:Seattle Genetics: Consultancy, Other: Investigator in a clinical trial; Merck: Other: Investigator in a clinical trial; Neumedicine: Consultancy; Soligenix: Consultancy; Galderma: Consultancy; Genentech: Other: Investigator in a clinical trial; Innate Pharma: Other: Investigator in a clinical trial; Kyowa Hakko Kirin: Consultancy, Honoraria, Other, Research Funding; Millenium: Consultancy, Other: Investigator in a clinical trial; Eisai: Consultancy, Other: Investigator in a clinical trial; Actelion: Consultancy, Other: Investigator in a clinical trial; Celgene: Consultancy; MiRagen: Consultancy; Horizon: Consultancy.