In the largest evaluation of fatal ICI-associated toxic effects published to date to our knowledge, we observed early onset of death with varied causes and frequencies depending on therapeutic regimen. Clinicians across disciplines should be aware of these uncommon lethal complications.

In melanoma patients with preexisting ADs or major irAEs with ipilimumab, anti-PD-1 induced relatively frequent immune toxicities, but these were often mild, easily managed and did not necessitate discontinuation of therapy, and a significant proportion of patients achieved clinical responses. The results support that anti-PD-1 can be administered safely and can achieve clinical benefit in patients with preexisting ADs or prior major irAEs with ipilimumab.

BACKGROUND Antibodies inhibiting the programmed death receptor 1 (PD-1) have shown significant activity in the treatment of advanced cutaneous melanoma. The efficacy and safety of PD-1 blockade in patients with uveal melanoma has not been well characterized. METHODS 58 stage IV uveal melanoma patients received PD-1 or PD-L1 antibodies between 2009 and 2015 at nine academic centers. Patients who were evaluable for response were eligible for analysis. Imaging was performed every 12-weeks and at the investigators’ discretion. Safety and clinical efficacy outcomes including best overall response (BOR), progression-free survival (PFS), overall survival (OS) were determined retrospectively. RESULTS Of 56 eligible patients, 48 (86%) had received prior therapy and 35 (63%) had been treated with ipilimumab. Three patients had an objective response to ipilimumab and 8 patients had stable disease as the best response. 38 (68%) received pembrolizumab, 16 (29%) received nivolumab, and 2 (4%) received atezolizumab. Objective tumor responses were observed in two patients for an overall response rate of 3.6% (95% CI 1.8-22.5%). Stable disease (≥ 6 months) was observed in 5 (9%) patients. The median PFS was 2.6 months (95% CI 2.4-2.8 months) and the median OS was 7.6 months (95% CI 0.7-14.6 months). There was no association between prior treatment with ipilimumab or liver directed therapy and PFS or OS. Treatment was well tolerated and only 1 patient discontinued treatment due to toxicity. CONCLUSIONS PD-1 and PD-L1 antibodies rarely confer durable remissions in patients with metastatic uveal melanoma. Clinical trial enrollment should be prioritized in this population.

Cancer is a disease of aging, and aged cancer patients have a poorer prognosis. This may be due to accumulated cellular damage, decreases in adaptive immunity, and chronic inflammation. However, the effects of the aged microenvironment on tumor progression have been largely unexplored. Since dermal fibroblasts can have profound impacts on melanoma progression1–4 we examined whether age-related changes in dermal fibroblasts could drive melanoma metastasis and response to targeted therapy. We find that aged fibroblasts secrete a Wnt antagonist, sFRP2, which activates a multi-step signaling cascade in melanoma cells that results in a decrease in β-catenin and MITF, and ultimately the loss of a key redox effector, APE1. Loss of APE1 attenuates the response of melanoma cells to ROS-induced DNA damage, rendering them more resistant to targeted therapy (vemurafenib). Age-related increases in sFRP2 also augment both angiogenesis and metastasis of melanoma cells. These data provide an integrated view of how fibroblasts in the aged microenvironment contribute to tumor progression, offering new paradigms for the design of therapy for the elderly.

Patients who discontinued CTLA-4/PD-1 blockade for severe irAEs had relatively high rates of recurrent or distinct toxicities with anti-PD-1 resumption. However, many patients, particularly with combination-induced colitis, tolerated anti-PD-1 rechallenge well, and this approach can be considered in selected patients.

We have shown that the aged microenvironment increases melanoma metastasis, and decreases response to targeted therapy, and here we queried response to anti-PD1. We analyzed the relationship between age, response to anti-PD1, and prior therapy in 538 patients. We used mouse models of melanoma, to analyze the intratumoral immune microenvironment in young versus aged mice and confirmed our findings in human melanoma biopsies. Patients over the age of 60 responded more efficiently to anti-PD-1, and likelihood of response to anti-PD-1 increased with age, even when we controlled for prior MAPKi therapy. Placing genetically identical tumors in aged mice (52 weeks) significantly increased their response to anti-PD1 as compared with the same tumors in young mice (8 weeks). These data suggest that this increased response in aged patients occurs even in the absence of a more complex mutational landscape. Next, we found that young mice had a significantly higher population of regulatory T cells (Tregs), skewing the CD8:Treg ratio. FOXP3 staining of human melanoma biopsies revealed similar increases in Tregs in young patients. Depletion of Tregs using anti-CD25 increased the response to anti-PD1 in young mice. While there are obvious limitations to our study, including our inability to conduct a meta-analysis due to a lack of available data, and our inability to control for mutational burden, there is a remarkable consistency in these data from over 500 patients across 8 different institutes worldwide. These results stress the importance of considering age as a factor for immunotherapy response. .

Background Acquired resistance to BRAF inhibitors (BRAFi) is a near-universal phenomenon caused by numerous genetic and non-genetic alterations. In this study, we evaluated the spectrum, onset, pattern of progression, and subsequent clinical outcomes associated with specific mechanisms of resistance. Methods We compiled clinical and genetic data from 100 patients with 132 tissue samples obtained at progression on BRAFi therapy from 3 large, previously published studies of BRAFi resistance. These samples were subjected to whole exome sequencing and/or PCR-based genetic testing. Results Among 132 samples, putative resistance mechanisms were identified in 58%, including NRAS or KRAS mutations (20%), BRAF splice variants (16%), BRAFV600E/K amplifications (13%), MEK1/2 mutations (7%), and non-MAPK pathway alterations (11%). Marked heterogeneity was observed within tumors and patients; 18 of 19 patients (95%) with >1 progression biopsy had distinct/unknown drivers of resistance between samples. NRAS mutations were associated with vemurafenib use (p=0.045) and intracranial metastases (p=0.036), and MEK1/2 mutations correlated with hepatic progression (p=0.011). Progression-free survival and overall survival were similar across resistance mechanisms. The median survival after disease progression was 6.9 months, and responses to subsequent BRAF and MEK inhibition were uncommon (2 of 15; 13%). Post-progression outcomes did not correlate with specific acquired BRAFi resistance mechanisms. Conclusions This is the first study to systematically characterize the clinical implications of particular acquired BRAFi resistance mechanisms in patients with BRAF-mutant melanoma largest study to compile the landscape of resistance. Despite marked heterogeneity of resistance mechanisms within patients, NRAS mutations correlated with vemurafenib use and intracranial disease involvement.

Background Therapeutic antibodies against programmed death receptor 1 (PD-1) are considered front-line therapy in metastatic melanoma. The efficacy of PD-1 blockade for patients with biologically distinct melanomas arising from acral and mucosal surfaces has not been well described. Methods A multi-institutional retrospective cohort analysis identified adults with advanced acral and mucosal melanoma treated with nivolumab or pembrolizumab as standard clinical practice, via expanded access programs, or published prospective trials. Objective responses were determined utilizing investigator-assessed Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Progression-free (PFS) and overall survival (OS) were assessed using Kaplan-Meier methods. Results 60 individuals were identified; 25 (42%) with acral and 35 (58%) with mucosal melanoma. Fifty-one (85%) patients had received prior therapy, including 77% with prior ipilimumab. Forty patients (67%) received pembrolizumab at 2mg/kg or 10mg/kg and 20 (33%) received nivolumab at 1mg/kg or 3mg/kg every 2–3 weeks. ORR (95% confidence interval, CI) was 32% (15–54%) in acral and 23% (10–40%) in mucosal melanoma. After a median follow up of 20 months in acral and 10.6 months in mucosal, median PFS was 4.1 months and 3.9 months, respectively. Only two patients (3%) discontinued treatment due to toxicity. Conclusions Response rates to PD-1 blockade in patients with acral and mucosal melanomas were comparable to published rates in cutaneous melanoma and support the routine use of PD-1 blockade in clinical practice. Further investigation is needed to identify the mechanisms of response and resistance to therapy in these subtypes.