Tumor and Microenvironment Evolution during Immunotherapy with Nivolumab.

The mechanisms by which immune checkpoint blockade modulates tumor evolution during therapy are unclear. We assessed genomic changes in tumors from 68 patients with advanced melanoma, who progressed on ipilimumab or were ipilimumab-naive, before and after nivolumab initiation (CA209-038 study). Tumors were analyzed by whole-exome, transcriptome, and/or T cell receptor (TCR) sequencing. In responding patients, mutation and neoantigen load were reduced from baseline, and analysis of intratumoral heterogeneity during therapy demonstrated differential clonal evolution within tumors and putative selection against neoantigenic mutations on-therapy. Transcriptome analyses before and during nivolumab therapy revealed increases in distinct immune cell subsets, activation of specific transcriptional networks, and upregulation of immune checkpoint genes that were more pronounced in patients with response. Temporal changes in intratumoral TCR repertoire revealed expansion of T cell clones in the setting of neoantigen loss. Comprehensive genomic profiling data in this study provide insight into nivolumab's mechanism of action.

Nivolumab with or without ipilimumab in patients with recurrent or metastatic cervical cancer (CheckMate 358): a phase 1-2, open-label, multicohort trial.

BACKGROUND: In preliminary findings from the recurrent or metastatic cervical cancer cohort of CheckMate 358, nivolumab showed durable anti-tumour responses, and the combination of nivolumab plus ipilimumab showed promising clinical activity. Here, we report long-term outcomes from this cohort. METHODS: CheckMate 358 was a phase 1-2, open-label, multicohort trial. The metastatic cervical cancer cohort enrolled patients from 30 hospitals and cancer centres across ten countries. Female patients aged 18 years or older with a histologically confirmed diagnosis of squamous cell carcinoma of the cervix with recurrent or metastatic disease, an Eastern Cooperative Oncology Group performance status of 0 or 1, and up to two previous systemic therapies were enrolled into the nivolumab 240 mg every 2 weeks group, the randomised groups (nivolumab 3 mg/kg every 2 weeks plus ipilimumab 1 mg/kg every 6 weeks [NIVO3 plus IPI1] or nivolumab 1 mg/kg every 3 weeks plus ipilimumab 3 mg/kg every 3 weeks for four cycles then nivolumab 240 mg every 2 weeks [NIVO1 plus IPI3]), or the NIVO1 plus IPI3 expansion group. All doses were given intravenously. Patients were randomly assigned (1:1) to NIVO3 plus IPI1 or NIVO1 plus IPI3 via an interactive voice response system. Treatment continued until disease progression, unacceptable toxicity, or consent withdrawal, or for up to 24 months. The primary endpoint was investigator-assessed objective response rate. Anti-tumour activity and safety were analysed in all treated patients. This study is registered with ClinicalTrials.gov (NCT02488759) and is now completed. FINDINGS: Between October, 2015, and March, 2020, 193 patients were recruited in the recurrent or metastatic cervical cancer cohort of CheckMate 358, of whom 176 were treated. 19 patients received nivolumab monotherapy, 45 received NIVO3 plus IPI1, and 112 received NIVO1 plus IPI3 (45 in the randomised group and 67 in the expansion group). Median follow-up times were 19·9 months (IQR 8·2-44·8) with nivolumab, 12·6 months (7·8-37·1) with NIVO3 plus IPI1, and 16·7 months (7·2-27·5) with pooled NIVO1 plus IPI3. Objective response rates were 26% (95% CI 9-51; five of 19 patients) with nivolumab, 31% (18-47; 14 of 45 patients) with NIVO3 plus IPI1, 40% (26-56; 18 of 45 patients) with randomised NIVO1 plus IPI3, and 38% (29-48; 43 of 112 patients) with pooled NIVO1 plus IPI3. The most common grade 3-4 treatment-related adverse events were diarrhoea, hepatic cytolysis, hyponatraemia, pneumonitis, and syncope (one [5%] patient each; nivolumab group), diarrhoea, increased gamma-glutamyl transferase, increased lipase, and vomiting (two [4%] patients each; NIVO3 plus IPI1 group), and increased lipase (nine [8%] patients) and anaemia (seven [6%] patients; pooled NIVO1 plus IPI3 group). Serious treatment-related adverse events were reported in three (16%) patients in the nivolumab group, 12 (27%) patients in the NIVO3 plus IPI1 group, and 47 (42%) patients in the pooled NIVO1 plus IPI3 group. There was one treatment-related death due to immune-mediated colitis in the NIVO1 plus IPI3 group. INTERPRETATION: Nivolumab monotherapy and nivolumab plus ipilimumab combination therapy showed promise in the CheckMate 358 study as potential treatment options for recurrent or metastatic cervical cancer. Future randomised controlled trials of nivolumab plus ipilimumab or other dual immunotherapy regimens are warranted to confirm treatment benefit in this patient population. FUNDING: Bristol Myers Squibb and Ono Pharmaceutical.

Immune-related encephalitis after immune checkpoint inhibitor therapy.

BACKGROUND: Immune checkpoint inhibitors (ICI) have revolutionized cancer treatment but can trigger immune-related encephalitis. We report one of the largest case series of patients with immune-related encephalitis and review of the literature. METHODS: Retrospective series of patients with immune-related encephalitis and literature review. RESULTS: Fourteen patients with cancer treated with ICI (50% combination therapy) developed immune-related encephalitis. Diagnostic testing revealed cerebral spinal fluid (CSF) lymphocytic pleocytosis (85%) and elevated protein (69%), abnormal brain magnetic resonance imaging(MRI) (33%) or brain FDG-PET (25%), electroencephalogram (EEG) abnormalities (30%), and autoantibodies (31%). Encephalitis treatment included: corticosteroids (86%), intravenous immunoglobulin (IVIg) (36%), plasmapheresis (7%), and rituximab (29%). There were no deaths and 12 patients had significant recovery, although long-term complications were observed. All patients discontinued ICI. Longitudinal follow-up demonstrated anti-cancer response to ICI at 3 months (85%) and 6 months post-ICI initiation (77%). A literature review identified 132 patients with immune-related encephalitis. Most were treated with PD-1 inhibitors (18% combination). Common abnormalities included elevated CSF protein (84%) or pleocytosis (77%), abnormal brain MRI (65%), or autoantibodies (47%). Nearly all were treated with corticosteroids, many required additional therapy with IVIg (26%) or rituximab (12%). Most patients had clinical improvement (81%) but a minority (10%) had a clinical relapse after completing corticosteroid taper. ICIs were resumed in 7 patients (5%), with relapse in 3. CONCLUSIONS AND RELEVANCE: Immune-related encephalitis is treatable and improves with corticosteroids in most cases but may require additional immunosuppression. Re-emergence of encephalitis is rare and does not typically result in adverse outcomes, and this should be considered in neurological immune-related adverse event management guidelines.

PD-1 Blockade with Pembrolizumab in Advanced Merkel-Cell Carcinoma.

BACKGROUND: Merkel-cell carcinoma is an aggressive skin cancer that is linked to exposure to ultraviolet light and the Merkel-cell polyomavirus (MCPyV). Advanced Merkel-cell carcinoma often responds to chemotherapy, but responses are transient. Blocking the programmed death 1 (PD-1) immune inhibitory pathway is of interest, because these tumors often express PD-L1, and MCPyV-specific T cells express PD-1. METHODS: In this multicenter, phase 2, noncontrolled study, we assigned adults with advanced Merkel-cell carcinoma who had received no previous systemic therapy to receive pembrolizumab (anti-PD-1) at a dose of 2 mg per kilogram of body weight every 3 weeks. The primary end point was the objective response rate according to Response Evaluation Criteria in Solid Tumors, version 1.1. Efficacy was correlated with tumor viral status, as assessed by serologic and immunohistochemical testing. RESULTS: A total of 26 patients received at least one dose of pembrolizumab. The objective response rate among the 25 patients with at least one evaluation during treatment was 56% (95% confidence interval [CI], 35 to 76); 4 patients had a complete response, and 10 had a partial response. With a median follow-up of 33 weeks (range, 7 to 53), relapses occurred in 2 of the 14 patients who had had a response (14%). The response duration ranged from at least 2.2 months to at least 9.7 months. The rate of progression-free survival at 6 months was 67% (95% CI, 49 to 86). A total of 17 of the 26 patients (65%) had virus-positive tumors. The response rate was 62% among patients with MCPyV-positive tumors (10 of 16 patients) and 44% among those with virus-negative tumors (4 of 9 patients). Drug-related grade 3 or 4 adverse events occurred in 15% of the patients. CONCLUSIONS: In this study, first-line therapy with pembrolizumab in patients with advanced Merkel-cell carcinoma was associated with an objective response rate of 56%. Responses were observed in patients with virus-positive tumors and those with virus-negative tumors. (Funded by the National Cancer Institute and Merck; ClinicalTrials.gov number, NCT02267603.).

BRAF-V600 mutational status affects recurrence patterns of melanoma brain metastasis.

Brain metastasis is common and carries a poor prognosis in melanoma. A single institution, retrospective cohort of 225 melanoma patients was analyzed to determine if BRAF-V600 mutational status was associated with brain metastasis. Eighty-three of the 225 patients (37%) had BRAF-V600 mutations. At initial diagnosis, BRAF-V600 mutations were associated with younger age (p ≤ 0.001), higher proportion of females (p = 0.0037), higher AJCC stage (p = 0.030), regional lymph node involvement (p = 0.047), and family history of cancer (p = 0.044). Compared to BRAF-WT, BRAF-V600 patients had an increased risk of brain metastasis in multivariate analysis (OR = 2.24; 95% CL = 1.10-4.58; p = 0.027). However, BRAF-V600 patients treated with a selective BRAF inhibitor (BRAFi) had a similar risk of brain metastasis compared to BRAF-WT patients (OR = 1.00; 95% CL = 0.37-2.65; p = 0.98). Moreover, treatment with BRAFi significantly prolonged the time from initial diagnosis to brain metastasis diagnosis (HR = 0.30; 95% CL = 0.11-0.79; p = 0.015). Compared to other tissues, the brain was the most frequent site of metastasis in BRAF-V600 patients without BRAFi (42% ± 7%). The frequency of brain metastasis was lower in BRAF-WT and BRAF-V600 patients with BRAFi (25% ± 4% and 25% ± 8%, respectively). The proportion of patients with brain metastasis as the only site was 40%, 60%, and 0% in the BRAF-WT, BRAF-V600 without BRAFi, and BRAF-V600 with BRAFi groups, respectively. This study provides evidence on the clinical importance of BRAF-V600 mutations and BRAF inhibition in the progression to melanoma brain metastasis.

Safety, activity, and immune correlates of anti-PD-1 antibody in cancer.

BACKGROUND: Blockade of programmed death 1 (PD-1), an inhibitory receptor expressed by T cells, can overcome immune resistance. We assessed the antitumor activity and safety of BMS-936558, an antibody that specifically blocks PD-1. METHODS: We enrolled patients with advanced melanoma, non-small-cell lung cancer, castration-resistant prostate cancer, or renal-cell or colorectal cancer to receive anti-PD-1 antibody at a dose of 0.1 to 10.0 mg per kilogram of body weight every 2 weeks. Response was assessed after each 8-week treatment cycle. Patients received up to 12 cycles until disease progression or a complete response occurred. RESULTS: A total of 296 patients received treatment through February 24, 2012. Grade 3 or 4 drug-related adverse events occurred in 14% of patients; there were three deaths from pulmonary toxicity. No maximum tolerated dose was defined. Adverse events consistent with immune-related causes were observed. Among 236 patients in whom response could be evaluated, objective responses (complete or partial responses) were observed in those with non-small-cell lung cancer, melanoma, or renal-cell cancer. Cumulative response rates (all doses) were 18% among patients with non-small-cell lung cancer (14 of 76 patients), 28% among patients with melanoma (26 of 94 patients), and 27% among patients with renal-cell cancer (9 of 33 patients). Responses were durable; 20 of 31 responses lasted 1 year or more in patients with 1 year or more of follow-up. To assess the role of intratumoral PD-1 ligand (PD-L1) expression in the modulation of the PD-1-PD-L1 pathway, immunohistochemical analysis was performed on pretreatment tumor specimens obtained from 42 patients. Of 17 patients with PD-L1-negative tumors, none had an objective response; 9 of 25 patients (36%) with PD-L1-positive tumors had an objective response (P=0.006). CONCLUSIONS: Anti-PD-1 antibody produced objective responses in approximately one in four to one in five patients with non-small-cell lung cancer, melanoma, or renal-cell cancer; the adverse-event profile does not appear to preclude its use. Preliminary data suggest a relationship between PD-L1 expression on tumor cells and objective response. (Funded by Bristol-Myers Squibb and others; ClinicalTrials.gov number, NCT00730639.).

Safety and immunologic correlates of Melanoma GVAX, a GM-CSF secreting allogeneic melanoma cell vaccine administered in the adjuvant setting.

BACKGROUND: Limited adjuvant treatment options exist for patients with high-risk surgically resected melanoma. This first-in-human study investigated the safety, tolerability and immunologic correlates of Melanoma GVAX, a lethally irradiated granulocyte-macrophage colony stimulating factor (GM-CSF)-secreting allogeneic whole-cell melanoma vaccine, administered in the adjuvant setting. METHODS: Patients with stage IIB-IV melanoma were enrolled following complete surgical resection. Melanoma GVAX was administered intradermally once every 28 days for four cycles, at 5E7 cells/cycle (n = 3), 2E8 cells/cycle (n = 9), or 2E8 cells/cycle preceded by cyclophosphamide 200 mg/m(2) to deplete T regulatory cells (Tregs; n = 8). Blood was collected before each vaccination and at 4 and 6 months after treatment initiation for immunologic studies. Vaccine injection site biopsies and additional blood samples were obtained 2 days after the 1st and 4th vaccines. RESULTS: Among 20 treated patients, 18 completed 4 vaccinations. Minimal treatment-related toxicity was observed. One patient developed vitiligo and patches of white hair during the treatment and follow-up period. Vaccine site biopsies demonstrated complex inflammatory infiltrates, including significant increases in eosinophils and PD-1+ lymphocytes from cycle 1 to cycle 4 (P < 0.05). Serum GM-CSF concentrations increased significantly in a dose-dependent manner 48 h after vaccination (P = 0.0086), accompanied by increased numbers of activated circulating monocytes (P < 0.0001) and decreased percentages of myeloid-derived suppressor cells among monocytes (CD14+ , CD11b+ , HLA-DR low or negative; P = 0.002). Cyclophosphamide did not affect numbers of circulating Tregs. No significant changes in anti-melanoma immunity were observed in peripheral T cells by interferon-gamma ELIPSOT, or immunoglobulins by serum Western blotting. CONCLUSION: Melanoma GVAX was safe and tolerable in the adjuvant setting. Pharmacodynamic testing revealed complex vaccine site immune infiltrates and an immune-reactive profile in circulating monocytic cell subsets. These findings support the optimization of Melanoma GVAX with additional monocyte and dendritic cell activators, and the potential development of combinatorial treatment regimens with synergistic agents. TRIAL REGISTRATION: NCT01435499.

Nivolumab + Tacrolimus + Prednisone ± Ipilimumab for Kidney Transplant Recipients With Advanced Cutaneous Cancers.

PURPOSE: Cancer-related mortality rates among kidney transplant recipients (KTR) are high, but these patients have largely been excluded from trials of immune checkpoint inhibitors because of immunosuppression and risk of treatment-related allograft loss (TRAL). We conducted a prospective clinical trial testing nivolumab (NIVO) + tacrolimus (TACRO) + prednisone (PRED) ± ipilimumab (IPI) in KTR with advanced cutaneous cancers. METHODS: Adult KTR with advanced melanoma or basal, cutaneous squamous, or Merkel cell carcinomas were eligible. Immunosuppression was standardized to TACRO (serum trough 2-5 ng/mL) + PRED 5 mg once daily. Patients then received NIVO 480 mg IV once every 4 weeks. The primary composite end point was partial or complete (tumor) response (CR) or stable disease per RECIST v1.1 without allograft loss at 16W. Patients with progressive disease (PD) could receive IPI 1 mg/kg IV + NIVO 3 mg/kg once every 3 weeks × 4 followed by NIVO. Donor-derived cell-free DNA (dd-cfDNA) levels were measured approximately once every 2 weeks as a potential predictor of allograft rejection. RESULTS: Among eight evaluable patients, none met the trial's primary end point. All eight patients experienced PD on NIVO + TACRO + PRED; TRAL occurred in one patient. Six patients then received IPI + NIVO + TACRO + PRED. Best overall responses: two CR (one with TRAL) and four PD (one with TRAL). In total, 7 of 8 pre-NIVO tumor biopsies contained a paucity of infiltrating immune cells. In total, 2 of 5 on-NIVO biopsies demonstrated moderate immune infiltrates; both patients later experienced a CR to IPI + NIVO. In 2 of 3 patients with TRAL, dd-cfDNA elevations occurred 10 and 15 days before increases in serum creatinine. CONCLUSION: In most KTR with advanced skin cancer, TACRO + PRED provides insufficient allograft protection and compromises immune-mediated tumor regression after administration of NIVO ± IPI. Elevated dd-cfDNA levels can signal treatment-related allograft rejection earlier than rises in serum creatinine.

Phase I Study of Single-Agent Anti-Programmed Death-1 (MDX-1106) in Refractory Solid Tumors: Safety, Clinical Activity, Pharmacodynamics, and Immunologic Correlates.

PURPOSE: Programmed death-1 (PD-1), an inhibitory receptor expressed on activated T cells, may suppress antitumor immunity. This phase I study sought to determine the safety and tolerability of anti-PD-1 blockade in patients with treatment-refractory solid tumors and to preliminarily assess antitumor activity, pharmacodynamics, and immunologic correlates. PATIENTS AND METHODS: Thirty-nine patients with advanced metastatic melanoma, colorectal cancer (CRC), castrate-resistant prostate cancer, non-small-cell lung cancer (NSCLC), or renal cell carcinoma (RCC) received a single intravenous infusion of anti-PD-1 (MDX-1106) in dose-escalating six-patient cohorts at 0.3, 1, 3, or 10 mg/kg, followed by a 15-patient expansion cohort at 10 mg/kg. Patients with evidence of clinical benefit at 3 months were eligible for repeated therapy. RESULTS: Anti-PD-1 was well tolerated: one serious adverse event, inflammatory colitis, was observed in a patient with melanoma who received five doses at 1 mg/kg. One durable complete response (CRC) and two partial responses (PRs; melanoma, RCC) were seen. Two additional patients (melanoma, NSCLC) had significant lesional tumor regressions not meeting PR criteria. The serum half-life of anti-PD-1 was 12 to 20 days. However, pharmacodynamics indicated a sustained mean occupancy of > 70% of PD-1 molecules on circulating T cells ≥ 2 months following infusion, regardless of dose. In nine patients examined, tumor cell surface B7-H1 expression appeared to correlate with the likelihood of response to treatment. CONCLUSION: Blocking the PD-1 immune checkpoint with intermittent antibody dosing is well tolerated and associated with evidence of antitumor activity. Exploration of alternative dosing regimens and combinatorial therapies with vaccines, targeted therapies, and/or other checkpoint inhibitors is warranted.

Survival, Durable Tumor Remission, and Long-Term Safety in Patients With Advanced Melanoma Receiving Nivolumab.

PURPOSE: Programmed cell death 1 (PD-1) is an inhibitory receptor expressed by activated T cells that downmodulates effector functions and limits the generation of immune memory. PD-1 blockade can mediate tumor regression in a substantial proportion of patients with melanoma, but it is not known whether this is associated with extended survival or maintenance of response after treatment is discontinued. PATIENTS AND METHODS: Patients with advanced melanoma (N = 107) enrolled between 2008 and 2012 received intravenous nivolumab in an outpatient setting every 2 weeks for up to 96 weeks and were observed for overall survival, long-term safety, and response duration after treatment discontinuation. RESULTS: Median overall survival in nivolumab-treated patients (62% with two to five prior systemic therapies) was 16.8 months, and 1- and 2-year survival rates were 62% and 43%, respectively. Among 33 patients with objective tumor regressions (31%), the Kaplan-Meier estimated median response duration was 2 years. Seventeen patients discontinued therapy for reasons other than disease progression, and 12 (71%) of 17 maintained responses off-therapy for at least 16 weeks (range, 16 to 56+ weeks). Objective response and toxicity rates were similar to those reported previously; in an extended analysis of all 306 patients treated on this trial (including those with other cancer types), exposure-adjusted toxicity rates were not cumulative. CONCLUSION: Overall survival following nivolumab treatment in patients with advanced treatment-refractory melanoma compares favorably with that in literature studies of similar patient populations. Responses were durable and persisted after drug discontinuation. Long-term safety was acceptable. Ongoing randomized clinical trials will further assess the impact of nivolumab therapy on overall survival in patients with metastatic melanoma.

A new American Joint Committee on Cancer staging system for cutaneous squamous cell carcinoma: creation and rationale for inclusion of tumor (T) characteristics.

BACKGROUND: The incidence of cutaneous squamous cell carcinoma (cSCC) is increasing. Although most patients achieve complete remission with surgical treatment, those with advanced disease have a poor prognosis. The American Joint Committee on Cancer (AJCC) is responsible for the staging criteria for all cancers. For the past 20 years, the AJCC cancer staging manual has grouped all nonmelanoma skin cancers, including cSCC, together for the purposes of staging. However, based on new evidence, the AJCC has determined that cSCC should have a separate staging system in the 7th edition AJCC staging manual. OBJECTIVE: We sought to present the rationale for and characteristics of the new AJCC staging system specific to cSCC tumor characteristics (T). METHODS: The Nonmelanoma Skin Cancer Task Force of AJCC reviewed relevant data and reached expert consensus in creating the 7th edition AJCC staging system for cSCC. Emphasis was placed on prospectively accumulated data and multivariate analyses. Concordance with head and neck cancer staging system was also achieved. RESULTS: A new AJCC cSCC T classification is presented. The T classification is determined by tumor diameter, invasion into cranial bone, and high-risk features, including anatomic location, tumor thickness and level, differentiation, and perineural invasion. LIMITATIONS: The data available for analysis are still suboptimal, with limited prospective outcomes trials and few multivariate analyses. CONCLUSIONS: The new AJCC staging system for cSCC incorporates tumor-specific (T) staging features and will encourage coordinated, consistent collection of data that will be the basis of improved prognostic systems in the future.

Interleukin-2, Ipilimumab, and Anti-PD-1: clinical management and the evolving role of immunotherapy for the treatment of patients with metastatic melanoma.

Treatment of metastatic melanoma has changed dramatically in the past 5 years with the approval of six new agents (vemurafenib, dabrafenib, trametinib, ipilimumab, pembrolizumab, and nivolumab) by the US Food and Drug Administration (FDA). This review will compare the immunotherapies recently approved by the FDA (ipilimumab, nivolumab and pembrolizumab) with the long-approved immunotherapy, interleukin-2. Additional consideration will be given to the evolving landscape, including the opportunities for combination regimens. Immunotherapies have distinct mechanisms of action and unique response kinetics that differ from conventional cytotoxic and targeted therapies, and have a range of adverse events that can be safely managed by experienced health-care providers. Data suggest immunotherapies can result in long-term survival in a proportion of patients. This dynamic and evolving field of immunotherapy for melanoma will continue to offer challenges in terms of optimal patient management for the foreseeable future.

An Open-Label, Randomized, Multi-Center Study Comparing the Sequence of High Dose Aldesleukin (Interleukin-2) and Ipilimumab (Yervoy) in Patients with Metastatic Melanoma.

Combination immunotherapy with sequential administration may enhance metastatic melanoma (MM) patients with long-term disease control. High Dose Aldesleukin/Recombinant Interleukin-2 (HD rIL-2) and ipilimumab (IPI) offer complementary mechanisms against MM. This phase IV study assessed the sequenced use of HD rIL-2 and IPI in MM patients. Eligible Stage IV MM patients were randomized to treatment with either two courses of HD rIL-2(600,000 IU/kg) followed by four doses of IPI 3 mg/kg or vice-versa. The primary objective was to compare one-year overall survival (OS) with historical control (46%, Hodi et al., NEJM 2010). Secondary objectives were 1-year progression-free survival (PFS), objective response rate (ORR), and adverse events (AEs) profile. Evaluable Population (EP) included patients who received at least 50% of planned treatment with each drug. Thirteen and 16 patients were randomized to receive HD rIL-2 first, and IPI first, respectively. One-year OS rate was 75% for intention to treat population. Eighteen patients were included in EP, 8 in HD rIL-2, 10 in IPI first arm. In EP, 1-year OS, PFS and ORR rates were 87%, 68%, and 50%, respectively. The frequency of AEs was similar in both arms with 13 patients experiencing Grade 3 or higher AEs, 3 resulting in the end of study participation. There was one HD rIL-2-related death, from cerebral hemorrhage due to thrombocytopenia. In this study with small sample size, HD rIL-2 and IPI were safe to administer sequentially in MM patients and showed more than additive effects. 1-year OS was superior to that of IPI alone from historical studies.

Three-year survival, correlates and salvage therapies in patients receiving first-line pembrolizumab for advanced Merkel cell carcinoma.

BACKGROUND: Merkel cell carcinoma (MCC) is an aggressive skin cancer associated with poor survival. Programmed cell death-1 (PD-1) pathway inhibitors have shown high rates of durable tumor regression compared with chemotherapy for MCC. The current study was undertaken to assess baseline and on-treatment factors associated with MCC regression and 3-year survival, and to explore the effects of salvage therapies in patients experiencing initial non-response or tumor progression after response or stable disease following first-line pembrolizumab therapy on Cancer Immunotherapy Trials Network-09/KEYNOTE-017. METHODS: In this multicenter phase II trial, 50 patients with advanced unresectable MCC received pembrolizumab 2 mg/kg every 3 weeks for ≤2 years. Patients were followed for a median of 31.8 months. RESULTS: Overall response rate to pembrolizumab was 58% (complete response 30%+partial response 28%; 95% CI 43.2 to 71.8). Among 29 responders, the median response duration was not reached (NR) at 3 years (range 1.0+ to 51.8+ months). Median progression-free survival (PFS) was 16.8 months (95% CI 4.6 to 43.4) and the 3-year PFS was 39.1%. Median OS was NR; the 3-year OS was 59.4% for all patients and 89.5% for responders. Baseline Eastern Cooperative Oncology Group performance status of 0, greater per cent tumor reduction, completion of 2 years of treatment and low neutrophil-to-lymphocyte ratio were associated with response and longer survival. Among patients with initial disease progression or those who developed progression after response or stable disease, some had extended survival with subsequent treatments including chemotherapies and immunotherapies. CONCLUSIONS: This study represents the longest available follow-up from any first-line anti-programmed death-(ligand) 1 (anti-PD-(L)1) therapy in MCC, confirming durable PFS and OS in a proportion of patients. After initial tumor progression or relapse following response, some patients receiving salvage therapies survived. Improving the management of anti-PD-(L)1-refractory MCC remains a challenge and a high priority. TRIAL REGISTRATION NUMBER: NCT02267603.

Neoadjuvant Nivolumab for Patients With Resectable Merkel Cell Carcinoma in the CheckMate 358 Trial.

PURPOSE: Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer commonly driven by the Merkel cell polyomavirus (MCPyV). The programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) immunosuppressive pathway is often upregulated in MCC, and advanced metastatic MCC frequently responds to PD-1 blockade. We report what we believe to be the first trial of anti-PD-1 in the neoadjuvant setting for resectable MCC. METHODS: In the phase I/II CheckMate 358 study of virus-associated cancer types, patients with resectable MCC received nivolumab 240 mg intravenously on days 1 and 15. Surgery was planned on day 29. Tumor regression was assessed radiographically and microscopically. Tumor MCPyV status, PD-L1 expression, and tumor mutational burden (TMB) were assessed in pretreatment tumor biopsies. RESULTS: Thirty-nine patients with American Joint Committee on Cancer stage IIA-IV resectable MCC received ≥ 1 nivolumab dose. Three patients (7.7%) did not undergo surgery because of tumor progression (n = 1) or adverse events (n = 2). Any-grade treatment-related adverse events occurred in 18 patients (46.2%), and grade 3-4 events in 3 patients (7.7%), with no unexpected toxicities. Among 36 patients who underwent surgery, 17 (47.2%) achieved a pathologic complete response (pCR). Among 33 radiographically evaluable patients who underwent surgery, 18 (54.5%) had tumor reductions ≥ 30%. Responses were observed regardless of tumor MCPyV, PD-L1, or TMB status. At a median follow-up of 20.3 months, median recurrence-free survival (RFS) and overall survival were not reached. RFS significantly correlated with pCR and radiographic response at the time of surgery. No patient with a pCR had tumor relapse during observation. CONCLUSION: Nivolumab administered approximately 4 weeks before surgery in MCC was generally tolerable and induced pCRs and radiographic tumor regressions in approximately one half of treated patients. These early markers of response significantly predicted improved RFS. Additional investigation of these promising findings is warranted.

Rescue therapy for patients with anti-PD-1-refractory Merkel cell carcinoma: a multicenter, retrospective case series.

Merkel cell carcinoma (MCC) is a rare but clinically aggressive cancer with a high mortality rate. In recent years, antibodies blocking the interactions among PD-1 and its ligands have generated durable tumor regressions in patients with advanced MCC. However, there is a paucity of data regarding effective therapy for patients whose disease is refractory to PD-1 pathway blockade. This retrospective case series describes a heterogeneous group of patients treated with additional immune checkpoint blocking therapy after MCC progression through anti-PD-1. Among 13 patients treated with anti-CTLA-4, alone or in combination with anti-PD-1, objective responses were seen in 4 (31%). Additionally, one patient with MCC refractory to anti-PD-1 and anti-CTLA-4 experienced tumor regression with anti-PD-L1. Our report - the largest case series to date describing this patient population - provides evidence that sequentially-administered salvage immune checkpoint blocking therapy can potentially activate anti-tumor immunity in patients with advanced anti-PD-1-refractory MCC and provides a strong rationale for formally testing these agents in multicenter clinical trials. Additionally, to the best of our knowledge, our report is the first to demonstrate possible anti-tumor activity of second-line treatment with a PD-L1 antibody in a patient with anti-PD-1-refractory disease.

Persistent mutant oncogene specific T cells in two patients benefitting from anti-PD-1.

BACKGROUND: Several predictive biomarkers are currently approved or are under investigation for the selection of patients for checkpoint blockade. Tumor PD-L1 expression is used for stratification of non-small cell lung (NSCLC) patients, with tumor mutational burden (TMB) also being explored with promising results, and mismatch-repair deficiency is approved for tumor site-agnostic disease. While tumors with high PD-L1 expression, high TMB, or mismatch repair deficiency respond well to checkpoint blockade, tumors with lower PD-L1 expression, lower mutational burdens, or mismatch repair proficiency respond much less frequently. CASE PRESENTATION: We studied two patients with unexpected responses to checkpoint blockade monotherapy: a patient with PD-L1-negative and low mutational burden NSCLC and one with mismatch repair proficient colorectal cancer (CRC), both of whom lack the biomarkers associated with response to checkpoint blockade, yet achieved durable clinical benefit. Both maintained T-cell responses in peripheral blood to oncogenic driver mutations - BRAF-N581I in the NSCLC and AKT1-E17K in the CRC - years after treatment initiation. Mutation-specific T cells were also found in the primary tumor and underwent dynamic perturbations in the periphery upon treatment. CONCLUSIONS: These findings suggest that T cell responses to oncogenic driver mutations may be more prevalent than previously appreciated and could be harnessed in immunotherapeutic treatment, particularly for patients who lack the traditional biomarkers associated with response. Comprehensive studies are warranted to further delineate additional predictive biomarkers and populations of patients who may benefit from checkpoint blockade.

Durable Tumor Regression and Overall Survival in Patients With Advanced Merkel Cell Carcinoma Receiving Pembrolizumab as First-Line Therapy.

PURPOSE: Merkel cell carcinoma (MCC) is an aggressive skin cancer often caused by the Merkel cell polyomavirus. Clinical trials of programmed cell death-1 pathway inhibitors for advanced MCC (aMCC) demonstrate increased progression-free survival (PFS) compared with historical chemotherapy data. However, response durability and overall survival (OS) data are limited. PATIENTS AND METHODS: In this multicenter phase II trial (Cancer Immunotherapy Trials Network-09/Keynote-017), 50 adults naïve to systemic therapy for aMCC received pembrolizumab (2 mg/kg every 3 weeks) for up to 2 years. Radiographic responses were assessed centrally per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. RESULTS: Among 50 patients, the median age was 70.5 years, and 64% had Merkel cell polyomavirus-positive tumors. The objective response rate (ORR) to pembrolizumab was 56% (complete response [24%] plus partial response [32%]; 95% CI, 41.3% to 70.0%), with ORRs of 59% in virus-positive and 53% in virus-negative tumors. Median follow-up time was 14.9 months (range, 0.4 to 36.4+ months). Among 28 responders, median response duration was not reached (range, 5.9 to 34.5+ months). The 24-month PFS rate was 48.3%, and median PFS time was 16.8 months (95% CI, 4.6 months to not estimable). The 24-month OS rate was 68.7%, and median OS time was not reached. Although tumor viral status did not correlate with ORR, PFS, or OS, there was a trend toward improved PFS and OS in patients with programmed death ligand-1-positive tumors. Grade 3 or greater treatment-related adverse events occurred in 14 (28%) of 50 patients and led to treatment discontinuation in seven (14%) of 50 patients, including one treatment-related death. CONCLUSION: Here, we present the longest observation to date of patients with aMCC receiving first-line anti-programmed cell death-1 therapy. Pembrolizumab demonstrated durable tumor control, a generally manageable safety profile, and favorable OS compared with historical data from patients treated with first-line chemotherapy.

Correction to: persistent mutant oncogene specific T cells in two patients benefitting from anti-PD-1.

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