A gut microbial signature for combination immune checkpoint blockade across cancer types

Immune checkpoint blockade (ICB) targeting programmed cell death protein 1 (PD-1) and cytotoxic T lymphocyte protein 4 (CTLA-4) can induce remarkable, yet unpredictable, responses across a variety of cancers. Studies suggest that there is a relationship between a cancer patient's gut microbiota composition and clinical response to ICB; however, defining microbiome-based biomarkers that generalize across cohorts has been challenging. This may relate to previous efforts quantifying microbiota to species (or higher taxonomic rank) abundances, whereas microbial functions are often strain specific. Here, we performed deep shotgun metagenomic sequencing of baseline fecal samples from a unique, richly annotated phase 2 trial cohort of patients with diverse rare cancers treated with combination ICB (n = 106 discovery cohort). We demonstrate that strain-resolved microbial abundances improve machine learning predictions of ICB response and 12-month progression-free survival relative to models built using species-rank quantifications or comprehensive pretreatment clinical factors. Through a meta-analysis of gut metagenomes from a further six comparable studies (n = 364 validation cohort), we found cross-cancer (and cross-country) validity of strain-response signatures, but only when the training and test cohorts used concordant ICB regimens (anti-PD-1 monotherapy or combination anti-PD-1 plus anti-CTLA-4). This suggests that future development of gut microbiome diagnostics or therapeutics should be tailored according to ICB treatment regimen rather than according to cancer type.

Chemotherapy after immune checkpoint inhibitor failure in metastatic melanoma: a retrospective multicentre analysis

INTRODUCTION

Despite remarkably improved outcomes with immune checkpoint inhibition, many patients with metastatic melanoma will eventually require further therapy. Chemotherapy has limited activity when used first-line but can alter the tumour microenvironment and does improve efficacy when used in combination with immunotherapy in lung cancer. Whether chemotherapy after checkpoint inhibitor failure has relevant activity in patients with metastatic melanoma is unknown.

METHODS

Patients with metastatic melanoma treated with chemotherapy after progression on immunotherapy with checkpoint inhibitors were identified retrospectively from 24 melanoma centres. Objective response rate (ORR), progression-free survival (PFS), overall survival (OS) and safety were examined.

RESULTS

In total, 463 patients were treated between 2007 and 2017. Fifty-six per cent had received PD-1-based therapy before chemotherapy. Chemotherapy regimens included carboplatin + paclitaxel (32%), dacarbazine (25%), temozolomide (15%), taxanes (9%, nab-paclitaxel 4%), fotemustine (6%) and others (13%). Median duration of therapy was 7.9 weeks (0-108). Responses included 0.4% complete response (CR), 12% partial response (PR), 21% stable disease (SD) and 67% progressive disease (PD). Median PFS was 2.6 months (2.2, 3.0), and median PFS in responders was 8.7 months (6.3, 16.3), respectively. Twelve-month PFS was 12% (95% CI 2-15%). In patients who had received anti-PD-1 before chemotherapy, the ORR was 11%, and median PFS was 2.5 months (2.1, 2.8). The highest activity was achieved with single-agent taxanes (N = 40), with ORR 25% and median PFS 3.9 months (2.1, 6.2). Median OS from chemotherapy start was 7.1 months (6.5, 8.0). Subsequent treatment with checkpoint inhibitors achieved a response rate of 16% with a median PFS of 19.1 months (2.0-43.1 months). No unexpected toxicities were observed.

CONCLUSION

Chemotherapy has a low response rate and short PFS in patients with metastatic melanoma who have failed checkpoint inhibitor therapy, although activity varied between regimens. Chemotherapy has a limited role in the management of metastatic melanoma.

Combination immunotherapy with nivolumab and ipilimumab in patients with rare gynecological malignancies: results of the CA209-538 clinical trial

BACKGROUND

Patients with rare cancers represent 55% of all gynecological malignancies and have poor survival outcomes due to limited treatment options. Combination immunotherapy with the anti-programmed cell death protein 1 (anti-PD-1) antibody nivolumab and the anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4) antibody ipilimumab has demonstrated significant clinical efficacy across a range of common malignancies, justifying evaluation of this combination in rare gynecological cancers.

METHODS

This multicenter phase II study enrolled 43 patients with advanced rare gynecological cancers. Patients received induction treatment with nivolumab and ipilimumab at a dose of 3 mg/kg and 1 mg/kg, respectively, every 3 weeks for four doses. Treatment was continued with nivolumab monotherapy at 3 mg/kg every 2 weeks until disease progression or a maximum of 2 years. The primary endpoint was the proportion of patients with disease control at week 12 (complete response, partial response or stable disease (SD) by Response Evaluation Criteria In Solid Tumor V.1.1). Exploratory evaluations correlated clinical outcomes with tumor programmed death-ligand 1 (PD-L1) expression and tumor mutational burden (TMB).

RESULTS

The objective response rate in the radiologically evaluable population was 36% (12/33 patients) and in the intention-to-treat population was 28% (12/43 patients), with additional 7 patients obtaining SD leading to a disease control rate of 58% and 44%, respectively. Durable responses were seen across a range of tumor histologies. Thirty-one (72%) patients experienced an immune-related adverse event (irAE) with a grade 3/4 irAE observed in seven (16%) patients. Response rate was higher among those patients with baseline PD-L1 expression (≥1% on tumor cells) but was independent of TMB.

CONCLUSIONS

Ipilimumab and nivolumab combination treatment has significant clinical activity with a favorable safety profile across a range of advanced rare gynecological malignancies and warrants further investigation in these tumor types.

Blockade of the co-inhibitory molecule PD-1 unleashes ILC2-dependent antitumor immunity in melanoma

Group 2 innate lymphoid cells (ILC2s) are essential to maintain tissue homeostasis. In cancer, ILC2s can harbor both pro-tumorigenic and anti-tumorigenic functions, but we know little about their underlying mechanisms or whether they could be clinically relevant or targeted to improve patient outcomes. Here, we found that high ILC2 infiltration in human melanoma was associated with a good clinical prognosis. ILC2s are critical producers of the cytokine granulocyte-macrophage colony-stimulating factor, which coordinates the recruitment and activation of eosinophils to enhance antitumor responses. Tumor-infiltrating ILC2s expressed programmed cell death protein-1, which limited their intratumoral accumulation, proliferation and antitumor effector functions. This inhibition could be overcome in vivo by combining interleukin-33-driven ILC2 activation with programmed cell death protein-1 blockade to significantly increase antitumor responses. Together, our results identified ILC2s as a critical immune cell type involved in melanoma immunity and revealed a potential synergistic approach to harness ILC2 function for antitumor immunotherapies.

PDCD1 Polymorphisms May Predict Response to Anti-PD-1 Blockade in Patients With Metastatic Melanoma

A significant number of patients (pts) with metastatic melanoma do not respond to anti-programmed cell death 1 (PD1) therapies. Identifying predictive biomarkers therefore remains an urgent need. We retrospectively analyzed plasma DNA of pts with advanced melanoma treated with PD-1 antibodies, nivolumab or pembrolizumab, for five PD-1 genotype single nucleotide polymorphisms (SNPs): PD1.1 (rs36084323, G>A), PD1.3 (rs11568821, G>A), PD1.5 (rs2227981, C>T) PD1.6 (rs10204225, G>A) and PD1.9 (rs2227982, C>T). Clinico-pathological and treatment parameters were collected, and presence of SNPs correlated with response, progression free survival (PFS) and overall survival (OS). 115 patients were identified with a median follow up of 18.7 months (range 0.26 – 52.0 months). All were Caucasian; 27% BRAF V600 mutation positive. At PD-1 antibody commencement, 36% were treatment-naïve and 52% had prior ipilimumab. The overall response rate was 43%, 19% achieving a complete response. Overall median PFS was 11.0 months (95% CI 5.4 - 17.3) and median OS was 31.1 months (95% CI 23.2 - NA). Patients with the G/G genotype had more complete responses than with A/G genotype (16.5% vs. 2.6% respectively) and the G allele of PD1.3 rs11568821 was significantly associated with a longer median PFS than the AG allele, 14.1 vs. 7.0 months compared to the A allele (p=0.04; 95% CI 0.14 – 0.94). No significant association between the remaining SNPs and responses, PFS or OS were observed. Despite limitations in sample size, this is the first study to demonstrate an association of a germline PD-1 polymorphism and PFS in response to anti-PD-1 therapy in pts with metastatic melanoma. Extrinsic factors like host germline polymorphisms should be considered with tumor intrinsic factors as predictive biomarkers for immune checkpoint regulators.

OP0194 GENERALIZED IMMUNE ACTIVATION IN STRUCTURES RELATED TO PMR OR GCA ON PET/CT ASSESSMENT DOES NOT OCCUR IN IMMUNE CHECKPOINT INHIBITOR-TREATED PATIENTS WHO DO NOT GO ON TO DEVELOP RHEUMATIC IMMUNE-RELATED ADVERSE EVENTS

Background:

The pathogenesis of rheumatic immune-related adverse events (irAEs) from checkpoint inhibitor cancer immunotherapy directed against programmed cell death protein 1 (PD-1) and programmed death ligand 1 (PD-L1) remains unknown, even though they are a consequence of pharmacologic inhibition of a specific immune mechanism. Given that some irAEs resemble polymyalgia rheumatica (PMR) or giant cell arteritis (GCA), a disease whose pathogenesis is poorly understood, observations regarding the pathogenesis of PMR-like or GCA-like irAEs are of significant interest. One proposed pathogenic mechanism involves generalized immune activation leading to a spectrum of subclinical disease. Interrogation of this hypothesis may be aided by PET/CT, which is frequently utilized for oncological staging purposes but is also useful in classical PMR or GCA diagnosis. If PMR or GCA irAEs merely represent a spectrum of generalized immune activation, low-grade subclinical PMR or GCA-related changes on PET/CT might be expected to be seen in patients who receive immunotherapy, irrespective of whether they develop clinically evident rheumatic irAEs.

Objectives:

This study investigated whether such changes occurred in patients receiving immunotherapy who did not develop clinically evident rheumatic irAEs.

Methods:

Consecutive patients exposed to PD-1 or PD-L1 inhibitor immunotherapy at a single center had scintigraphic uptake calculated by a nuclear medicine physician experienced in assessment of vasculitis. Patients were included if they had had 18F-fluorodeoxyglucose (18F-FDG) PET/CT imaging both within the two weeks prior to immunotherapy initiation and after at least eleven weeks of immunotherapy. Patients who went on to develop a rheumatic irAE were excluded, as were patients with scintigraphic evidence of liver metastases owing to their potential influence on scoring of uptake. Quantification of 18F-FDG uptake by maximum standardized uptake values (maximum standard unit value, SUVmax) was performed at sites relevant to PMR or GCA (17 sites relevant to PMR, 17 sites relevant to GCA) in paired scans, and the difference calculated.

Results:

Twenty-four patients receiving nivolumab, pembrolizumab or avelumab met the inclusion criteria, primarily for melanoma, non-small cell lung cancer, or lymphoma. The mean age was 67 at the time of the first scan, 71% were male, and 66% had a complete or partial oncological response at best response. No statistically or clinically significant difference in SUVmax was noted at any PMR or GCA-relevant anatomical site interrogated. Latent class analysis did not reveal clusters identifiable by cancer type, best response, or presence of combination therapy.

Conclusion:

Patients treated with PD-1/PD-L1 inhibitors without clinically evident rheumatic irAEs do not develop subclinical PMR or GCA-like changes on PET/CT. This supports the proposition that PMR-like and GCA-like irAEs are a distinct entity with stochastic onset, and do not simply represent generalized immune activation induced by immunotherapy.

Acknowledgements:

David Liew is the recipient of the Ronald John Gleghorn Bursary from the University of Melbourne.

Disclosure of Interests:

David Liew: None declared, Aurora Poon: None declared, Christopher McMaster: None declared, Claire Owen Speakers bureau: Roche, Jessica Leung Speakers bureau: GIlead, Novartis, Albert Frauman: None declared, Jonathan Cebon: None declared, Andrew Scott: None declared, Russell Buchanan: None declared

Combination immunotherapy with ipilimumab and nivolumab in patients with advanced adrenocortical carcinoma: a subgroup analysis of CA209-538

Background: Adrenocortical carcinoma is a rare malignancy, with poor prognosis and limited treatment options for patients with advanced disease. Chemotherapy is the current standard first-line treatment, providing only a modest survival benefit. There is only limited treatment experience with immunotherapy using single-agent anti-PD-1/PD-L1 therapy. To date no clinical trials have been reported using combination immunotherapy with anti-CTLA-4 and anti-PD-1 blockade in this patient population. Methods: CA209-538 is a prospective multicentre clinical trial in patients with advanced rare cancers. Participants received the anti-PD-1 antibody nivolumab (3 mg/kg IV) and the anti-CTLA-4 antibody ipilimumab (1 mg/kg IV) every three weeks for four doses, followed by nivolumab (3 mg/kg IV) every two weeks and continued for up to 96 weeks, until disease progression or unacceptable toxicity. Response was assessed every 12 weeks by RECIST version 1.1. Primary endpoint was clinical benefit rate (complete response, partial response, stable disease at 12 weeks). Results: Six patients with adrenocortical carcinoma were enrolled and received treatment. Two patients (33%) have an ongoing partial response (10 and 25 months +) and two patients (33%) stable disease leading to a disease control rate of 66%. Both responders had tumors with a microsatellite instable phenotype. One patient rapidly progressed shortly after enrollment into the trial and did not undergo restaging. Immunotherapy-related toxicity was reported in all patients, with four patients (67%) experiencing grade 3/4 hepatitis leading to discontinuation of treatment. Conclusions: This is the first treatment experience using ipilimumab and nivolumab combination immunotherapy in patients with advanced adrenocortical carcinoma. Durable responses have been observed in a subset of patients suggesting that this treatment regimen should be further investigated in this patient population.

Ropporin-1 and 1B Are Widely Expressed in Human Melanoma and Evoke Strong Humoral Immune Responses

Antibodies that block immune regulatory checkpoints (programmed cell death 1, PD-1 and cytotoxic T-lymphocyte-associated antigen 4, CTLA-4) to mobilise immunity have shown unprecedented clinical efficacy against cancer, demonstrating the importance of antigen-specific tumour recognition. Despite this, many patients still fail to benefit from these treatments and additional approaches are being sought. These include mechanisms that boost antigen-specific immunity either by vaccination or adoptive transfer of effector cells. Other than neoantigens, epigenetically regulated and shared antigens such as NY-ESO-1 are attractive targets; however, tissue expression is often heterogeneous and weak. Therefore, peptide-specific therapies combining multiple antigens rationally selected to give additive anti-cancer benefits are necessary to achieve optimal outcomes. Here, we show that Ropporin-1 (ROPN1) and 1B (ROPN1B), cancer restricted antigens, are highly expressed and immunogenic, inducing humoral immunity in patients with advanced metastatic melanoma. By multispectral immunohistochemistry, 88.5% of melanoma patients tested (n = 54/61) showed ROPN1B expression in at least 1 of 2/3 tumour cores in tissue microarrays. Antibody responses against ROPN1A and ROPN1B were detected in 71.2% of melanoma patients tested (n = 74/104), with increased reactivity seen with more advanced disease stages. Thus, ROPN1A and ROPN1B may indeed be viable targets for cancer immunotherapy, alone or in combination with other cancer antigens, and could be combined with additional therapies such as immune checkpoint blockade.

Evaluation of Combination Nivolumab and Ipilimumab Immunotherapy in Patients With Advanced Biliary Tract Cancers: Subgroup Analysis of a Phase 2 Nonrandomized Clinical Trial

Importance

Biliary tract cancers represent a rare group of malignant conditions with very limited treatment options. Patients with advanced disease have a poor outcome with current therapies.

Objective

To evaluate the efficacy and safety of combination immunotherapy with nivolumab and ipilimumab in patients with advanced biliary tract cancers.

Design, Setting, and Participants

The CA209-538 prospective multicenter phase 2 nonrandomized clinical trial included patients with advanced rare cancers including patients with biliary tract cancers. This subgroup analysis evaluated 39 patients from CA209-538 with biliary tract cancers who were enrolled from December 2017 to December 2019. Most of the patients (n = 33) had experienced disease progression after 1 or more lines of therapy and had tumor tissue available for biomarker research.

Interventions

Patients received treatment with nivolumab at a dose of 3 mg/kg and ipilimumab at 1 mg/kg every 3 weeks for 4 doses, followed by nivolumab 3 mg/kg every 2 weeks and continued for up to 96 weeks until disease progression or the development of unacceptable toxic events.

Main Outcomes and Measures

The primary end point was disease control rate (complete remission, partial remission, or stable disease) as assessed by RECIST 1.1.

Results

Among the 39 patients included in this subgroup analysis of a phase 2 clinical trial (20 men, 19 women; mean [range] age, 65 [37-81] years), the objective response rate was 23% (n = 9) with a disease control rate of 44% (n = 17); all responders had received prior chemotherapy, and none had a microsatellite unstable tumor. Responses were exclusively observed in patients with intrahepatic cholangiocarcinoma and gallbladder carcinoma. The median duration of response was not reached (range, 2.5 to ≥23 months). The median progression-free survival was 2.9 months (95% CI, 2.2-4.6 months), and overall survival was 5.7 months (95% CI, 2.7-11.9 months). Immune-related toxic events were reported in 49% of patients (n = 19), with 15% (n = 6) experiencing grade 3 or 4 events.

Conclusions and Relevance

This subgroup analysis of a phase 2 clinical trial found that combination immunotherapy with nivolumab and ipilimumab was associated with substantial positive outcomes patients with advanced biliary tract cancers. This treatment compares favorably to single-agent anti-programmed cell death protein 1 (anti-PD-1) therapy and warrants further investigation. Ongoing translational research is focused on identifying biomarkers that can predict treatment response.

Trial Registration

ClinicalTrials.gov Identifier: NCT02923934.

BCL-XL is an actionable target for treatment of malignant pleural mesothelioma

Despite having one of the lowest survival rates of all cancers, there have been no new approved treatments for malignant pleural mesothelioma (MPM) in over a decade. Standard-of-care treatment relies on Cisplatin plus Pemetrexed chemotherapy. Here, we tested a suite of BH3-mimetic drugs targeting BCL-2 pro-survival proteins of the intrinsic apoptotic pathway. We found BCL-XL is the dominant pro-survival protein in a panel of cell lines in vitro, though potent, synergistic cell killing occurred with MCL-1 co-targeting. This correlates with high-level expression of BCL-XL and MCL-1 in cell lines and a large cohort of patient tumour samples. BCL-XL inhibition combined with Cisplatin also enhanced cell killing. In vivo BCL-XL inhibition was as effective as Cisplatin, and the combination enhanced tumour growth control and survival. Genetic ablation of MCL-1 also enhanced the effects of BCL-XL inhibitors, in vivo. Combined, these data provide a compelling rationale for the clinical investigation of BH3-mimetics targeting BCL-XL in MPM.

Migratory cues controlling B-lymphocyte trafficking in human lymph nodes

B-cell migration within lymph nodes (LNs) is crucial to adaptive immune responses. Chemotactic gradients are proposed to drive migration of B cells into follicles, followed by their relocation to specific zones of the follicle during activation, and ultimately egress. However, the molecular drivers of these processes and the cells generating chemotactic signals that affect B cells in human LNs are not well understood. We used immunofluorescence microscopy, flow cytometry and functional assays to study molecular mechanisms of B-cell migration within human LNs, and found subtle but important differences to previous murine models. In human LNs we find CXCL13 is prominently expressed at the follicular edge, often associated with fibroblastic reticular cells located in these areas, whereas follicular dendritic cells show minimal contribution to CXCL13 expression. Human B cells rapidly downregulate CXCR5 on encountering CXCL13, but recover CXCR5 expression in the CXCL13-low environment. These data suggest that the CXCL13 gradient in human LNs is likely to be different from that proposed in mice. We also identify CD68⁺ CD11c⁺ PU.1⁺ tingible body macrophages within both primary and secondary follicles as likely drivers of the sphingosine-1-phosphate (S1P) gradient that mediates B-cell egress from LNs, through their expression of the S1P-degrading enzyme, S1P lyase. Based on our findings, we present a model of B-cell migration within human LNs, which has both similarities and interesting differences to that proposed for mice.

Histological diagnosis of immune checkpoint inhibitor induced acute renal injury in patients with metastatic melanoma: a retrospective case series report

BACKGROUND

Immune checkpoint inhibitors (ICI) have become the standard of care in many oncological conditions but are associated with a spectrum of renal immune-related adverse events (IrAEs). We aimed to describe the spectrum, histology, management and outcomes of renal IrAE in patients with metastatic melanoma undergoing ICI therapy.

METHODS

We conducted a retrospective review of 23 patients with a diagnosis of metastatic melanoma treated with ICI between January 2017 and April 2019 who developed a renal IrAE. Baseline demographic data, biochemical and histopathological results, management and outcomes were analyzed.

RESULTS

The majority of patients who developed renal irAE were male and received combination immunotherapy. The median time of onset from initiation of ICI therapy to renal IrAE was 4 months. 52% of the treated renal IrAE had histopathologically confirmed renal IrAE. The most common histological pattern of injury was acute tubulo-interstitial nephritis (92%). One patient developed anti-GBM disease with non-dialysis dependent stage 5 CKD. In tubulointerstitial injury, there was no association between peak creatinine, renal recovery and histologically reported inflammation or fibrosis. Patients with renal IrAE demonstrated persisting renal dysfunction at 3, 6 and 12 months with a mean baseline, 3 and 12 month creatinine of 90.0 μmol/L, 127.0 μmol/L and 107.5 μmol/L respectively.

CONCLUSION

Renal IrAE is most commonly attributable to steroid responsive acute tubulointerstitial nephritis. The outcome of rarer pathologies such as anti-GBM disease may be adversely affected by a delayed diagnosis. There is persisting renal dysfunction following an episode of renal IrAE that may have impact on future renal and overall survival outcomes.

A pilot study of intrahepatic yttrium-90 microsphere radioembolization in combination with intravenous cisplatin for uveal melanoma liver-only metastases

BACKGROUND

Metastatic uveal melanoma is a highly aggressive disease with no standard of care treatment option. A large proportion of patients have liver-only metastatic disease which raises the question if liver-directed therapy can be efficacious in this subpopulation.

AIMS

The study aims to evaluate the safety and efficacy of radiosensitizing chemotherapy in combination with yttrium-90 microspheres in patients with uveal melanoma with liver-only metastases.

METHODS AND RESULTS

This single arm, open labeled, non-randomized study enrolled 10 patients with liver-only metastatic uveal melanoma between November 2012 and January 2018. Eligible patients received intrahepatic yttrium-90 microspheres followed by intravenous cisplatin (20 mg/m²) for 5 days. Ten patients were enrolled, but nine patients received treatment who were included in the final analysis with a median follow-up of 30 months (range 7 to 44). Five (50%) were female, five (50%) had an elevated lactate dehydrogenase (LDH), and one (10%) had prior anti-PD-1 therapy. The combination was well tolerated with no greater than or equal to grade 3 toxicity observed. The liver objective response rate (ORR) was 33% (3/9), the median progression-free survival (PFS) in the liver was 3 months (95% CI, 3-NA), and the extrahepatic PFS was 3 months (95% CI, 3-NA). Seventy-eight percent (7/9) received an immune checkpoint inhibitor on disease progression, with no responses seen. The median overall survival (OS) was 10 months (95% CI, 7-NA).

CONCLUSION

The combination of cisplatin with yttrium-90 microspheres was well tolerated; however, it was associated with intrahepatic disease control of relatively short duration. No responses were seen in patients treated with immune checkpoint inhibitors post radioembolization.

Immunotherapy of Ipilimumab and Nivolumab in Patients with Advanced Neuroendocrine Tumors: A Subgroup Analysis of the CA209-538 Clinical Trial for Rare Cancers

PURPOSE

Combination immunotherapy with anti-CTLA-4 and anti-PD-1 blockade has demonstrated significant clinical activity across several tumor types. Neuroendocrine tumors (NET) are a heterogeneous group of rare tumors with limited treatment options. CA209-538 is a clinical trial of combination immunotherapy with ipilimumab and nivolumab in rare cancers, including advanced NETs.

PATIENTS AND METHODS

CA209-538 is a prospective multicenter clinical trial in patients with advanced rare cancers. Patients received treatment with nivolumab at a dose of 3 mg/kg and ipilimumab at 1 mg/kg every three weeks for four doses, followed by nivolumab 3 mg/kg every two weeks and continued for up to 96 weeks, until disease progression or the development of unacceptable toxicity. Response was assessed every 12 weeks by RECIST 1.1. The primary endpoint was clinical benefit rate (CBR; complete remission + partial remission + stable disease).

RESULTS

Twenty-nine patients with advanced NETs received treatment. Three (10%) patients had low-, 13 (45%) had intermediate-, and 13 (45%) had high-grade tumors; lung was the most common primary site (39%). The objective response rate was 24% with a CBR of 72%; 43% of patients with pancreatic neuroendocrine neoplasms (NEN), and 33% of patients with atypical bronchial carcinoid achieved an objective response. The median progression-free survival was 4.8 months [95% confidence interval (CI): 2.7-10.5] and overall survival was 14.8 months (95% CI: 4.1-21.3). Immune-related toxicity was reported in 66% of patients with 34% experiencing grade 3/4 events.

CONCLUSIONS

Combination immunotherapy with ipilimumab and nivolumab demonstrated significant clinical activity in subgroups of patients with advanced NETs including patients with atypical bronchial carcinoid and high-grade pancreatic NENs.

Butyrophilin molecules govern γδ T cell reactivity against phosphoantigens

Humans have a minor lymphocyte population of gamma-delta (γδ) T cells. The majority of these express a recombined Vγ9Vδ2 T cell receptor (TCR) attractive to immunotherapy. This distinct TCR conveys reactivity to phosphorylated antigens (pAg) that derive from pathogens or accumulate inside tumour cells. Such T cell responses are regulated by butyrophilin (BTN) 3A1 and other membrane-related proteins present on antigen-presenting cells. However, the activation mechanism and direct molecular ligand recognised by the γδ TCR remain a crucial unresolved question. Herein, we used pAg-reactive TCR probes in a whole-genome screen to identify BTN2A1 as an essential ligand. In further investigation, we elucidated its functionality working in cis with BTN3A1. Also, a mutational analysis unveiled critical regions of the γδ TCR are positioned at opposite sides. We locate germ-line encoded residues of the Vγ9 chain were responsible for BTN2A1 binding, whereas two amino-acids of the Vδ2 chain were necessary for a complete response to pAg. In conclusion, we propose a dual-ligand complex model that senses pAg to evoke immune responses, wherein BTN2A1 sets the framework to develop new opportunities on γδ T cell-based immunotherapies.

Tracking extracellular vesicle phenotypic changes enables treatment monitoring in melanoma

Monitoring targeted therapy in real time for cancer patients could provide vital information about the development of drug resistance and improve therapeutic outcomes. Extracellular vesicles (EVs) have recently emerged as a promising cancer biomarker, and EV phenotyping shows high potential for monitoring treatment responses. Here, we demonstrate the feasibility of monitoring patient treatment responses based on the plasma EV phenotypic evolution using a multiplex EV phenotype analyzer chip (EPAC). EPAC incorporates the nanomixing-enhanced microchip and the multiplex surface-enhanced Raman scattering (SERS) nanotag system for direct EV phenotyping without EV enrichment. In a preclinical model, we observe the EV phenotypic heterogeneity and different phenotypic responses to the treatment. Furthermore, we successfully detect cancer-specific EV phenotypes from melanoma patient plasma. We longitudinally monitor the EV phenotypic evolution of eight melanoma patients receiving targeted therapy and find specific EV profiles involved in the development of drug resistance, reflecting the potential of EV phenotyping for monitoring treatment responses.

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale1-3. Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter4; identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation5,6; analyses timings and patterns of tumour evolution7; describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity8,9; and evaluates a range of more-specialized features of cancer genomes8,10-18.

Butyrophilin 2A1 is essential for phosphoantigen reactivity by γδ T cells

Gamma delta (γδ) T cells are essential to protective immunity. In humans, most γδ T cells express Vγ9Vδ2⁺ T cell receptors (TCRs) that respond to phosphoantigens (pAgs) produced by cellular pathogens and overexpressed by cancers. However, the molecular targets recognized by these γδTCRs are unknown. Here, we identify butyrophilin 2A1 (BTN2A1) as a key ligand that binds to the Vγ9⁺ TCR γ chain. BTN2A1 associates with another butyrophilin, BTN3A1, and these act together to initiate responses to pAg. Furthermore, binding of a second ligand, possibly BTN3A1, to a separate TCR domain incorporating Vδ2 is also required. This distinctive mode of Ag-dependent T cell activation advances our understanding of diseases involving pAg recognition and creates opportunities for the development of γδ T cell-based immunotherapies.

Anti-programmed cell death protein 1 (anti-PD1) immunotherapy induced autoimmune polyendocrine syndrome type II (APS-2): a case report and review of the literature

Background

Autoimmune polyendocrine syndrome type II (APS-2) is a rare constellation of autoimmune hypoadrenalism, thyroid dysfunction and/or type 1 diabetes (T1DM), usually occurring in the 3rd or 4th decades and associated with a human leukocyte antigen (HLA) DR3 or DR4 serotype. We detail the first report of an elderly woman developing the full triad of APS-2 shortly after commencing anti-programmed cell death protein 1 (anti-PD1) immune checkpoint inhibition for unresectable melanoma and review the literature for similar presentations secondary to anti-PD1 axis therapy.

Case

A 78-year-old female with advanced unresectable BRAF wild-type melanoma was treated with pembrolizumab (2 mg/kg 3-weekly). Three weeks following the first dose she developed fulminant autoimmune diabetes, with an initially low C-peptide denoting rapid destruction of ß-islet cells. Following stabilisation of her diabetes, two further doses of pembrolizumab was administered. She then represented with symptomatic hypoadrenalism and hypothyroidism, consistent with APS-2. Her HLA class II genotype was HLA-DRB1*04.16 (DR4 serotype), a recognised association with this syndrome. Her melanoma responded rapidly to anti-PD1 therapy, and a complete response (CR) was attained after four doses of pembrolizumab. Treatment was discontinued and her CR is ongoing.

Conclusion

This is the first report of the full triad of APS-2 developing in a genetically susceptible individual at the age of 78 after treatment with an anti-PD1 agent. Although scarcely reported, a literature review of similar reports seems to indicate a predilection for this syndrome in patients with HLA-DR4 serotypes. HLA Class II typing is not routinely recommended, but may provide useful predictive information for patients at risk of poly-endocrinopathy even in patients without a relevant personal or family history. Additional studies are required to determine if such testing would be useful and/or cost effective.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0713-y) contains supplementary material, which is available to authorized users.

BCL-XL and MCL-1 are the key BCL-2 family proteins in melanoma cell survival

Malignant melanoma is one of the most difficult cancers to treat due to its resistance to chemotherapy. Despite recent successes with BRAF inhibitors and immune checkpoint inhibitors, many patients do not respond or become resistant to these drugs. Hence, alternative treatments are still required. Due to the importance of the BCL-2-regulated apoptosis pathway in cancer development and drug resistance, it is of interest to establish which proteins are most important for melanoma cell survival, though the outcomes of previous studies have been conflicting. To conclusively address this question, we tested a panel of established and early passage patient-derived cell lines against several BH3-mimetic drugs designed to target individual or subsets of pro-survival BCL-2 proteins, alone and in combination, in both 2D and 3D cell cultures. None of the drugs demonstrated significant activity as single agents, though combinations targeting MCL-1 plus BCL-XL, and to a lesser extent BCL-2, showed considerable synergistic killing activity that was elicited via both BAX and BAK. Genetic deletion of BFL-1 in cell lines that express it at relatively high levels only had minor impact on BH3-mimetic drug sensitivity, suggesting it is not a critical pro-survival protein in melanoma. Combinations of MCL-1 inhibitors with BRAF inhibitors also caused only minimal additional melanoma cell killing over each drug alone, whilst combinations with the proteasome inhibitor bortezomib was more effective in multiple cell lines. Our data show for the first time that therapies targeting specific combinations of BCL-2 pro-survival proteins, namely MCL-1 plus BCL-XL and MCL-1 plus BCL-2, could have significant benefit for the treatment of melanoma.

Association of good oncological response to therapy with the development of rheumatic immune-related adverse events following PD-1 inhibitor therapy

AIM

To investigate whether any patient or treatment characteristics are associated with the development of rheumatic immune-related adverse events (irAEs) following programmed cell death protein 1 (PD-1) inhibitor therapy for cancer.

METHOD

This was a retrospective chart review of all patients who were dispensed nivolumab or pembrolizumab at a single center before 1 January, 2017, with follow-up until 1 July, 2017. Patients with any diagnosis of a non-cutaneous irAE were identified, regardless of severity, and rheumatic irAEs were characterized.

RESULTS

Of 244 episodes of therapy, a non-cutaneous irAE occurred in 72 (29.5%). Rheumatic irAEs were diagnosed in 19 episodes of therapy (7.8%), with 12 de novo diagnoses (5.1% of episodes without a pre-existing autoimmune rheumatic disease) and 7 exacerbations of existing disease. Review by a rheumatologist occurred in only 11 of these. Rheumatic irAEs were more common in patients with a good oncological response to therapy (relative risk [RR] 11.16), those being treated for melanoma (RR 2.94) and those who developed another non-cutaneous irAE (RR 2.64).

CONCLUSION

Rheumatic irAEs are relatively common with PD-1 inhibitor therapy, and appear to be associated with a good oncological response to therapy. Many rheumatic irAEs were not referred to rheumatological services. Prospective systematic investigation would be of benefit to explore these characteristics.

Real-world efficacy and toxicity of combined nivolumab and ipilimumab in patients with metastatic melanoma

BACKGROUND

There is limited real-world data on the efficacy and safety of combination programmed cell death protein-1 (PD-1) inhibitor, nivolumab and the cytotoxic T-lymphocyte antigen (CTLA-4) inhibitor ipilimumab.

METHOD

We retrospectively identified patients (pts) with metastatic melanoma treated with three-weekly nivolumab (1 mg/kg) in combination with ipilimumab (3 mg/kg) for four cycles followed by nivolumab monotherapy (3 mg/kg) fortnightly. Patient demographics and treatment parameters were collected and outcomes determined.

RESULTS

A total of 45 pts received combination treatment with a median follow up of 8.7 months (range 0.33-25.9 months). A total of 67% were male, and BRAF V600 mutations detected in 38%. At treatment commencement, 14 (31%) pts had brain metastases, 51% had an elevated LDH and 18 (40%) were treatment-naive. Almost a third (30%) required corticosteroids for symptom control or management of prior toxicities. Nineteen (42%) patients had prior anti-PD-1 therapy. The disease control rate (DCR) was 54% and objective response rate (ORR) was 29%. Of pts treated with prior immune checkpoint inhibitors, the DCR and ORR were 50% and 33%, respectively. Intracranial responses were observed in 18% (n = 2). The median progression-free survival (PFS) was 5.8 months (95% Confidence interval (CI), 2.9-14.1 months). PFS was higher in treatment naïve patients compared to those who had prior immunotherapy (6.2 months vs 4.9 months, P = 0.59). The median OS was 17.4 months (95% CI, 7.1-NR). pts requiring corticosteroids had a shorter PFS (4.9 months vs 6.8 months) and OS (7.1 months vs NR, P = 0.01).Treatment-related adverse events of any grade were experienced by 88% of pts, with 54% having grade 3-4 adverse events. Treatment discontinuation due to adverse events occurred in 44% of pts.

CONCLUSION

In this study, responses to combination immunotherapy were lower than reported. Patients treated with prior immunotherapy had similar responses as treatment-naïve pts. The toxicity profile seen in this study is similar to those reported in clinical trials.

Multiplex immunohistochemistry accurately defines the immune context of metastatic melanoma

A prospective study explored the heterogeneous nature of metastatic melanoma using Multiplex immunohistochemistry (IHC) and flow cytometry (FACS). Multiplex IHC data quantitated immune subset number present intra-tumoral (IT) vs the tumor stroma, plus distance of immune subsets from the tumor margin (TM). In addition, mIHC showed a close association between the presence of IT CD8⁺ T cells and PDL1 expression in melanoma, which was more prevalent on macrophages than on melanoma cells. In contrast, FACS provided more detailed information regarding the T cell subset differentiation, their activation status and expression of immune checkpoint molecules. Interestingly, mIHC detected significantly higher Treg numbers than FACS and showed preferential CD4⁺ T cell distribution in the tumor stroma. Based on the mIHC and FACS data, we provide a model which defines metastatic melanoma immune context into four categories using the presence or absence of PDL1⁺ melanoma cells and/or macrophages, and their location within the tumor or on the periphery, combined with the presence or absence of IT CD8⁺ T cells. This model interprets melanoma immune context as a spectrum of tumor escape from immune control, and provides a snapshot upon which interpretation of checkpoint blockade inhibitor (CBI) therapy responses can be built.

Delayed Autoimmune Toxicity Occurring Several Months After Cessation of Anti-PD-1 Therapy

Treatment with anti-programmed cell death protein 1 (PD-1) antibodies has demonstrated clinical efficacy in a whole range of malignancies including advanced melanoma, renal cell cancer, bladder cancer, and non-small cell lung cancer. Immune-related adverse events are a unique side effect of checkpoint regulator therapy including anti-PD-1 antibodies. Treatment-related autoimmunity can occur in any organ system, with the median onset usually within 5-15 weeks from the commencement of therapy, depending on the organ system involved. This study describes for the first time a case of delayed autoimmunity occurring 8 months after discontinuing treatment with the anti-PD-1 antibody nivolumab in a patient with metastatic melanoma. The case highlights the need for ongoing surveillance of patients treated with immune checkpoint inhibitors even after cessation of therapy, especially as patients increasingly stop treatment after achieving durable responses.

Characterising the phenotypic evolution of circulating tumour cells during treatment

Real-time monitoring of cancer cells' phenotypic evolution during therapy can provide vital tumour biology information for treatment management. Circulating tumour cell (CTC) analysis has emerged as a useful monitoring tool, but its routine usage is restricted by either limited multiplexing capability or sensitivity. Here, we demonstrate the use of antibody-conjugated and Raman reporter-coated gold nanoparticles for simultaneous labelling and monitoring of multiple CTC surface markers (named as "cell signature"), without the need for isolating individual CTCs. We observe cell heterogeneity and phenotypic changes of melanoma cell lines during molecular targeted treatment. Furthermore, we follow the CTC signature changes of 10 stage-IV melanoma patients receiving immunological or molecular targeted therapies. Our technique maps the phenotypic evolution of patient CTCs sensitively and rapidly, and shows drug-resistant clones having different CTC signatures of potential clinical value. We believe our proposed method is of general interest in the CTC relevant research and translation fields.

Autoantibodies May Predict Immune-Related Toxicity: Results from a Phase I Study of Intralesional Bacillus Calmette-Guérin followed by Ipilimumab in Patients with Advanced Metastatic Melanoma

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of advanced melanoma. The first ICI to demonstrate clinical benefit, ipilimumab, targets cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4); however, the long-term overall survival is just 22%. More than 40 years ago intralesional (IL) bacillus Calmette-Guérin (BCG), a living attenuated strain of Mycobacterium bovis, was found to induce tumor regression by stimulating cell-mediated immunity following a localized and self-limiting infection. We evaluated these two immune stimulants in combination with melanoma with the aim of developing a more effective immunotherapy and to assess toxicity. In this phase I study, patients with histologically confirmed stage III/IV metastatic melanoma received IL BCG injection followed by up to four cycles of intravenous ipilimumab (anti-CTLA-4) (ClinicalTrials.gov number NCT01838200). The trial was discontinued following treatment of the first five patients as the two patients receiving the escalation dose of BCG developed high-grade immune-related adverse events (irAEs) typical of ipilimumab monotherapy. These irAEs were characterized in both patients by profound increases in the repertoire of autoantibodies directed against both self- and cancer antigens. Interestingly, the induced autoantibodies were detected at time points that preceded the development of symptomatic toxicity. There was no overlap in the antigen specificity between patients and no evidence of clinical responses. Efforts to increase response rates through the use of novel immunotherapeutic combinations may be associated with higher rates of irAEs, thus the imperative to identify biomarkers of toxicity remains strong. While the small patient numbers in this trial do not allow for any conclusive evidence of predictive biomarkers, the observed changes warrant further examination of autoantibody repertoires in larger patient cohorts at risk of developing irAEs during their course of treatment. In summary, dose escalation of IL BCG followed by ipilimumab therapy was not well tolerated in advanced melanoma patients and showed no evidence of clinical benefit. Measuring autoantibody responses may provide early means for identifying patients at risk from developing severe irAEs during cancer immunotherapy.

Long-Term Outcomes in Patients With BRAF V600-Mutant Metastatic Melanoma Who Received Dabrafenib Combined With Trametinib

Purpose To report 5-year landmark analysis efficacy and safety outcomes in patients with BRAF V600-mutant metastatic melanoma (MM) who received BRAF inhibitor dabrafenib (D) and MEK inhibitor trametinib (T) combination therapy versus D monotherapy in the randomized phase II BRF113220 study part C. Patients and Methods BRAF inhibitor-naive patients with BRAF V600-mutant MM were randomly assigned 1:1:1 to receive D 150 mg twice a day, D 150 mg twice a day plus T 1 mg once daily, or D 150 mg twice a day plus T 2 mg once daily (D + T 150/2). Patients who received D monotherapy could cross over to D + T 150/2 postprogression. Efficacy and safety were analyzed 4 and 5 years after initiation in patients with ≥ 5 years of follow-up. Results As of October 13, 2016, 18 patients who received D + T 150/2 remained in the study (13 [24%] of 54 enrolled at this dose plus five [11%] of 45 initially administered D who crossed over to D + T). With D + T 150/2, overall survival (OS; 4 years, 30%; 5 years, 28%) and progression-free survival (4 and 5 years, both 13%) appeared to stabilize with extended follow-up. Increased OS was observed in patients who received D + T with baseline normal lactate dehydrogenase (5 years, 45%) and normal lactate dehydrogenase with fewer than three organ sites with metastasis (5 years, 51%). With extended follow-up, one additional patient who received D + T 150/2 improved from a partial to a complete response. No new safety signals were observed. Conclusion This 5-year analysis represents the longest follow-up to date with BRAF + MEK inhibitor combination therapy in BRAF V600-mutant MM. Consistent with trends observed in landmark analyses with shorter follow-up, this therapy elicits durable plateaus of long-term OS and progression-free survival that last ≥ 5 years in some patients with MM.

Identifying and targeting determinants of melanoma cellular invasion

Epithelial-to-mesenchymal transition is a critical process that increases the malignant potential of melanoma by facilitating invasion and dissemination of tumor cells. This study identified genes involved in the regulation of cellular invasion and evaluated whether they can be targeted to inhibit melanoma invasion. We identified Peroxidasin (PXDN), Netrin 4 (NTN4) and GLIS Family Zinc Finger 3 (GLIS3) genes consistently elevated in invasive mesenchymal-like melanoma cells. These genes and proteins were highly expressed in metastatic melanoma tumors, and gene silencing led to reduced melanoma invasion in vitro. Furthermore, migration of PXDN, NTN4 or GLIS3 siRNA transfected melanoma cells was inhibited following transplantation into the embryonic chicken neural tube compared to control siRNA transfected melanoma cells. Our study suggests that PXDN, NTN4 and GLIS3 play a functional role in promoting melanoma cellular invasion, and therapeutic approaches directed toward inhibiting the action of these proteins may reduce the incidence or progression of metastasis in melanoma patients.

Overall Survival with Combined Nivolumab and Ipilimumab in Advanced Melanoma

BACKGROUND

Nivolumab combined with ipilimumab resulted in longer progression-free survival and a higher objective response rate than ipilimumab alone in a phase 3 trial involving patients with advanced melanoma. We now report 3-year overall survival outcomes in this trial.

METHODS

We randomly assigned, in a 1:1:1 ratio, patients with previously untreated advanced melanoma to receive nivolumab at a dose of 1 mg per kilogram of body weight plus ipilimumab at a dose of 3 mg per kilogram every 3 weeks for four doses, followed by nivolumab at a dose of 3 mg per kilogram every 2 weeks; nivolumab at a dose of 3 mg per kilogram every 2 weeks plus placebo; or ipilimumab at a dose of 3 mg per kilogram every 3 weeks for four doses plus placebo, until progression, the occurrence of unacceptable toxic effects, or withdrawal of consent. Randomization was stratified according to programmed death ligand 1 (PD-L1) status, BRAF mutation status, and metastasis stage. The two primary end points were progression-free survival and overall survival in the nivolumab-plus-ipilimumab group and in the nivolumab group versus the ipilimumab group.

RESULTS

At a minimum follow-up of 36 months, the median overall survival had not been reached in the nivolumab-plus-ipilimumab group and was 37.6 months in the nivolumab group, as compared with 19.9 months in the ipilimumab group (hazard ratio for death with nivolumab plus ipilimumab vs. ipilimumab, 0.55 [P<0.001]; hazard ratio for death with nivolumab vs. ipilimumab, 0.65 [P<0.001]). The overall survival rate at 3 years was 58% in the nivolumab-plus-ipilimumab group and 52% in the nivolumab group, as compared with 34% in the ipilimumab group. The safety profile was unchanged from the initial report. Treatment-related adverse events of grade 3 or 4 occurred in 59% of the patients in the nivolumab-plus-ipilimumab group, in 21% of those in the nivolumab group, and in 28% of those in the ipilimumab group.

CONCLUSIONS

Among patients with advanced melanoma, significantly longer overall survival occurred with combination therapy with nivolumab plus ipilimumab or with nivolumab alone than with ipilimumab alone. (Funded by Bristol-Myers Squibb and others; CheckMate 067 ClinicalTrials.gov number, NCT01844505 .).

Oncolytic Virotherapy Promotes Intratumoral T Cell Infiltration and Improves Anti-PD-1 Immunotherapy

Here we report a phase 1b clinical trial testing the impact of oncolytic virotherapy with talimogene laherparepvec on cytotoxic T cell infiltration and therapeutic efficacy of the anti-PD-1 antibody pembrolizumab. Twenty-one patients with advanced melanoma were treated with talimogene laherparepvec followed by combination therapy with pembrolizumab. Therapy was generally well tolerated, with fatigue, fevers, and chills as the most common adverse events. No dose-limiting toxicities occurred. Confirmed objective response rate was 62%, with a complete response rate of 33% per immune-related response criteria. Patients who responded to combination therapy had increased CD8⁺ T cells, elevated PD-L1 protein expression, as well as IFN-γ gene expression on several cell subsets in tumors after talimogene laherparepvec treatment. Response to combination therapy did not appear to be associated with baseline CD8⁺ T cell infiltration or baseline IFN-γ signature. These findings suggest that oncolytic virotherapy may improve the efficacy of anti-PD-1 therapy by changing the tumor microenvironment. VIDEO ABSTRACT.

Pooled Analysis Safety Profile of Nivolumab and Ipilimumab Combination Therapy in Patients With Advanced Melanoma

Purpose The addition of nivolumab (anti-programmed death-1 antibody) to ipilimumab (anti-cytotoxic T-cell lymphocyte-associated 4 antibody) in patients with advanced melanoma improves antitumor response and progression-free survival but with a higher frequency of adverse events (AEs). This cross-melanoma study describes the safety profile of the approved nivolumab plus ipilimumab regimen. Methods This retrospective safety review on data from three trials (phase I, II, and III) included patients with advanced melanoma who received at least one dose of nivolumab 1 mg/kg plus ipilimumab 3 mg/kg every 3 weeks × 4 and then nivolumab 3 mg/kg every 2 weeks until disease progression or unacceptable toxicity while following established guidelines for AE management. Analyses were of all treatment-related AEs, select (immune-related) AEs, time to onset and resolution, and use of immune-modulating agents and their effects on outcome. Results Among 448 patients, median duration of follow-up was 13.2 months. Treatment-related grade 3/4 AEs occurred in 55.5% of patients; 35.7% had treatment-related AEs that led to discontinuation. The most frequent treatment-related select AEs of any grade were skin (64.3%) and GI (46.7%) and of grade 3/4, hepatic (17.0%) and GI (16.3%); 30.1% developed a grade 2 to 4 select AE in more than one organ category. Median time to onset of grade 3/4 treatment-related select AEs ranged from 3.1 (skin) to 16.3 (renal) weeks, and with the exclusion of endocrine AEs, median time to resolution from onset ranged from 1.9 (renal) to 4.5 (pulmonary) weeks, with resolution rates between 79% and 100% while using immune-modulating agents. Four (< 1%) on-study deaths were attributed to therapy. Conclusion Frequency of grade 3/4 treatment-related AEs was higher with nivolumab plus ipilimumab and occurred earlier than historical experience with either agent alone, but resolution rates were similar.

CMTM6 maintains the expression of PD-L1 and regulates anti-tumour immunity

Cancer cells exploit the expression of the programmed death-1 (PD-1) ligand 1 (PD-L1) to subvert T-cell-mediated immunosurveillance. The success of therapies that disrupt PD-L1-mediated tumour tolerance has highlighted the need to understand the molecular regulation of PD-L1 expression. Here we identify the uncharacterized protein CMTM6 as a critical regulator of PD-L1 in a broad range of cancer cells, by using a genome-wide CRISPR-Cas9 screen. CMTM6 is a ubiquitously expressed protein that binds PD-L1 and maintains its cell surface expression. CMTM6 is not required for PD-L1 maturation but co-localizes with PD-L1 at the plasma membrane and in recycling endosomes, where it prevents PD-L1 from being targeted for lysosome-mediated degradation. Using a quantitative approach to profile the entire plasma membrane proteome, we find that CMTM6 displays specificity for PD-L1. Notably, CMTM6 depletion decreases PD-L1 without compromising cell surface expression of MHC class I. CMTM6 depletion, via the reduction of PD-L1, significantly alleviates the suppression of tumour-specific T cell activity in vitro and in vivo. These findings provide insights into the biology of PD-L1 regulation, identify a previously unrecognized master regulator of this critical immune checkpoint and highlight a potential therapeutic target to overcome immune evasion by tumour cells.

Abstract CT099: A phase I study of intralesional Bacillus Calmette-Guerin (BCG) followed by ipilimumab therapy in patients with advanced metastatic melanoma

Background: Immunotherapies with checkpoint inhibitors have revolutionized the treatment of advanced melanomas. Nonetheless, a subset of patients fail to benefit clinically from these immunotherapeutics, and thus strategies aimed at inducing a favorable inflammatory tumor microenvironment prior to immunotherapy are currently being investigated by means of combination therapies. Bacillus Calmette-Guerin (BCG) is a living attenuated strain of Mycobacterium bovis that stimulates cell-mediated immunity by producing a localized and self-limiting infection. This immunostimulatory agent has shown evidence of anti-tumor activity in several clinical studies with suggested induction of non-specific immune responses, thereby warranting further investigation in a combination therapy setting.

Methods: This phase I study aimed to determine the safety, clinical efficacy and immunogenicity of the administration of intralesional BCG followed by up to four intravenous infusions of ipilimumab (anti-CTLA4) (NCT01838200). Patients with histologically confirmed stage III/IV metastatic melanoma with at least one injectable lesion, and no prior immunotherapy or autoimmune disease were recruited for this study. Patients received up to four 3 mg/kg ipilimumab infusions every 3 weeks from 36 days after intralesion BCG injection containing 0.16 - 0.64 x 106 colony-forming units. Serum samples were collected prior to each therapeutic intervention as a means of investigating immunogenicity. Humoral immune responses were investigated using the Immunome protein array, a high-content array with 1627 full-length, correctly folded, and fully functional immobilized proteins that enables the interrogation of the depth and breadth of the immune response.

Results: 5 patients were enrolled in this study, with 2 displaying high grade immune-related adverse events (irAEs) (grade 3 hepatitis and grade 4 colitis), which led to the early discontinuation of this trial. These irAEs were in accordance with ipilimumab-related reported toxicities. Furthermore, all patients displayed evidence of clinically progressive disease, with no evident therapeutic benefit. Patients displaying irAEs were characterized by drastic increases in their antibody repertoire towards tumor and self-antigens, when compared to those with no reported irAEs (42% vs. 3% of array content, respectively). This high order of de novo and induced antibodies was detected in time points preceding clinical detection of these high-grade toxicities. However, these antibody profiles did not overlap between patients, with unique antigen targets detected in each patient, suggesting evidence of a systemic B-cell deregulation, rather than an induced specific anti-tumor response.

Conclusions: Intralesional BCG followed by ipilimumab therapy was not well tolerated in advanced melanoma patients, and showed no evidence of clinical benefit. Investigating humoral immunity may offer a means to detect the early onset of irAEs in an immunotherapeutic clinical trial setting.

Citation Format: Jessica Duarte, Katherine Woods, Andreas Behren, Jonathan Cebon. A phase I study of intralesional Bacillus Calmette-Guerin (BCG) followed by ipilimumab therapy in patients with advanced metastatic melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT099. doi:10.1158/1538-7445.AM2017-CT099

PLX8394, a new generation BRAF inhibitor, selectively inhibits BRAF in colonic adenocarcinoma cells and prevents paradoxical MAPK pathway activation

BRAF inhibitors (BRAFi) are standard of care for the treatment of BRAF V600 mutation-driven metastatic melanoma, but can lead to paradoxical activation of the mitogen-activated protein kinase (MAPK) signalling pathway. This can result in the promotion of precancerous lesions and secondary neoplasms, mainly (but not exclusively) associated with pre-existing mutations in RAS genes. We previously reported a patient with synchronous BRAF-mutated metastatic melanoma and BRAF^wt/KRAS^G12D-metastatic colorectal cancer (CRC), whose CRC relapsed and progressed when treated with the BRAF inhibitor dabrafenib (GSK2118436). We used tissue from the resected CRC metastasis to derive a cell line, LM-COL-1, which directly and reliably mimicked the clinical scenario including paradoxical activation of the MAPK signalling pathway resulting in increased cell proliferation upon dabrafenib treatment. Novel BRAF inhibitors (PLX8394 and PLX7904), dubbed as “paradox breakers”, were developed to inhibit V600 mutated oncogenic BRAF without causing paradoxical MAPK pathway activation. In this study we used our LM-COL-1 model alongside multiple other CRC cell lines with varying mutational backgrounds to demonstrate and confirm that the paradox breaker PLX8394 retains on-target inhibition of mutated BRAF V600 without paradoxically promoting MAPK signalling.

Phase II Study of First-Line Trebananib Plus Sorafenib in Patients with Advanced Hepatocellular Carcinoma

Lessons Learned.

Trebananib leveraging anti‐angiogenic mechanism that is distinct from the classic sorafenib anti‐vascular endothelial growth factor inhibition did not demonstrate improved progression‐free survival at 4 months in patients with advanced hepatocellular carcinoma (HCC).

In support of previously reported high Ang‐2 levels’ association with poor outcome in HCC for patients, trebananib treatment with lower baseline Ang‐2 at study entry was associated with improved overall survival to 22 months and may suggest future studies to be performed within the context of low baseline Ang‐2.

Background.

Ang‐1 and Ang‐2 are angiopoietins thought to promote neovascularization via activation of the Tie‐2 angiopoietin receptor. Trebananib sequesters Ang‐1 and Ang‐2, preventing interaction with the Tie‐2 receptor. Trebananib plus sorafenib combination has acceptable toxicity. Elevated Ang‐2 levels are associated with poor prognosis in hepatocellular carcinoma (HCC).

Methods.

Patients with HCC, Eastern Cooperative Oncology Group ≤2, and Childs‐Pugh A received IV trebananib at 10 mg/kg or 15 mg/kg weekly plus sorafenib 400 mg orally twice daily. The study was planned for ≥78% progression‐free survival (PFS) rate at 4 months relative to 62% for sorafenib historical control (power = 80% α = 0.20). Secondary endpoints included safety, tolerability, overall survival (OS), and multiple biomarkers, including serum Ang‐2.

Results.

Thirty patients were enrolled sequentially in each of the two nonrandomized cohorts. Demographics were comparable between the two arms and the historical controls. PFS rates at 4 months were 57% and 54% on the 10 mg/kg and 15 mg/kg trebananib cohorts, respectively. Median OS was 17 and 11 months, respectively. Grade 3 and above events noted in ≥10% of patients included fatigue, hypertension, diarrhea, liver failure, palmar‐plantar erythrodysesthesia syndrome, dyspnea, and hypophosphatemia. One death was due to hepatic failure. Serum Ang‐2 dichotomized at the median was associated with improved OS in both cohorts.

Conclusion.

There was no improvement in PFS rate at 4 months in either cohort, when compared with sorafenib historical control.

Efficacy of anti-PD-1 therapy in patients with melanoma brain metastases

Background:

There is limited data on the efficacy of anti-programmed death 1 (PD-1) antibodies in patients (pts) with melanoma brain metastasis (BM), particularly those which are symptomatic.

Method:

We retrospectively assessed pts with melanoma BM treated with PD-1 antibodies, nivolumab and pembrolizumab. Clinicopathologic and treatment parameters were collected and outcomes determined for intracranial (IC) response rate (RR) using a modified RECIST criteria, with up to five IC target lesions used to determine IC response, disease control rate (DCR) and progression-free survival (PFS).

Results:

A total of 66 pts were identified with a median follow up of 7.0 months (range 0.8–24.5 months). A total of 68% were male and 45% BRAF V600 mutation positive. At PD-1 antibody commencement, 50% had an elevated LDH; 64% had local therapy to BM prior to commencing anti-PD1, of which 5% had surgical resection, 14% stereotactic radiosurgery (SRS), 18% whole-brain radiotherapy (WBRT), 27% had surgery and radiotherapy. Twenty-one per cent started anti-PD-1 as first line systemic therapy. No pt had prior anti-PD-1 treatment. The IC overall RR was 21 and DCR 56%. Responses occurred in 21% of pts with symptomatic BM. The median OS was 9.9 months (95% CI 6.93–17.74). Pts with symptomatic BM had shorter PFS than those without symptoms (2.7 vs 7.4 months, P=0.035) and numerically shorter OS (5.7 vs 13.0 months, P=0.068). Pts requiring corticosteroids also had a numerically shorter PFS (3.2 vs 7.4 months, P=0.081) and OS (4.8 vs 13.1 months, P=0.039).

Conclusions:

IC responses to anti-PD-1 antibodies occur in pts with BM, including those with symptomatic BM requiring corticosteroids. Prospective trials evaluating anti-PD-1 therapy in pts with BM are underway.

Whole-genome landscapes of major melanoma subtypes

Melanoma of the skin is a common cancer only in Europeans, whereas it arises in internal body surfaces (mucosal sites) and on the hands and feet (acral sites) in people throughout the world. Here we report analysis of whole-genome sequences from cutaneous, acral and mucosal subtypes of melanoma. The heavily mutated landscape of coding and non-coding mutations in cutaneous melanoma resolved novel signatures of mutagenesis attributable to ultraviolet radiation. However, acral and mucosal melanomas were dominated by structural changes and mutation signatures of unknown aetiology, not previously identified in melanoma. The number of genes affected by recurrent mutations disrupting non-coding sequences was similar to that affected by recurrent mutations to coding sequences. Significantly mutated genes included BRAF, CDKN2A, NRAS and TP53 in cutaneous melanoma, BRAF, NRAS and NF1 in acral melanoma and SF3B1 in mucosal melanoma. Mutations affecting the TERT promoter were the most frequent of all; however, neither they nor ATRX mutations, which correlate with alternative telomere lengthening, were associated with greater telomere length. Most melanomas had potentially actionable mutations, most in components of the mitogen-activated protein kinase and phosphoinositol kinase pathways. The whole-genome mutation landscape of melanoma reveals diverse carcinogenic processes across its subtypes, some unrelated to sun exposure, and extends potential involvement of the non-coding genome in its pathogenesis.

Abstract A78: Antibody profiling of melanoma patients using a custom protein microarray platform

There is substantial evidence that the mainly tumor-restricted aberrant expression of the highly immunogenic cancer-testis (CT) antigens across several different cancer types makes them attractive cancer diagnostic and predictive biomarkers. Therefore, we aimed to measure differences in CT antigen-specific antibody repertoires between melanoma patient samples, and assess whether these could identify novel diagnostic or prognostic biomarkers, which could aid in the detection and management of cancer. In order to detect and quantify CT-antigen-specific antibodies circulating in the serum or plasma of cancer patients, we co-developed a novel CT antigen microarray platform. This tool represents a high-throughput means of profiling antibody repertoires against over 100 cancer-restricted antigens in a highly reproducible manner with high sensitivity (detection limit: 10-100pg/ml) and specificity. In addition, it provides a significant advantage over tissue-based approaches, due to the ease of sample access without the need for invasive procedures. We carried out a retrospective serological study of antibody titers across a large cohort of eighty-eight mainly advanced malignant melanoma patients (8% unknown stage, 2% stage I, 10% stage II, 40% stage III and 40% stage IV) undergoing a variety of distinct cancer treatments (surgery, chemotherapy, radiotherapy, immunotherapy or none), using our recently developed and validated novel CT antigen microarray platform. We successfully identified abundant antibody titers towards two leading CT antigens, NY-ESO-1 and CTAG2 - a highly homologous pair - expressed across 50% (n = 44/88) and 45% (n = 40/88) of all patients, respectively, with reported diagnostic and clinical efficacy predictive biomarker potential. Furthermore, the overlap in antibody titers of this pair, most likely due to a shared immunogenic epitope, validated our array platform, showing consistency amongst our obtained results across patients. Additional abundant titers were found across fifteen further antigens, including several members of the melanoma antigen (MAGE) family, such as MAGEB1 (n = 30/88, 34%), MAGEB6 (n = 29/88, 33%), MAGEB5 (n = 26/88, 29%), MAGEA3 (n = 26/88, 29%) and MAGEA11 (n = 24/88, 27%). Abundant antibody titers towards at least one of these leading seventeen cancer antigens were detected across 82% of this cohort (n = 72/88), thus emphasizing the potential uses of these as diagnostic or prognostic biomarkers, warranting further larger studies. Furthermore, healthy individuals showed no detectable cancer-antigen-specific antibody titers, therefore highlighting the specificity of this tool in a cancer setting. In conclusion, we showed that our novel protein microarray platform represents a sensitive, high-throughput and customizable means to detect and quantify the presence of large panels of cancer-specific human antibodies in serum, obtaining consistently robust, high quality and reproducible data, and demonstrating its potential feasibility and inferred biological significance.

Citation Format: Jessica Duarte, Janique Peyper, Katherine Woods, Simon Chang-Hao Tsao, Jonathan Cebon, Jonathan Blackburn. Antibody profiling of melanoma patients using a custom protein microarray platform. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr A78.

A pilot study of peripheral blood BDCA-1 (CD1c) positive dendritic cells pulsed with NY-ESO-1 ISCOMATRIX™ adjuvant

AIM

Pilot clinical trial of NY-ESO-1 (ESO) protein in ISCOMATRIX™ adjuvant pulsed onto peripheral blood dendritic cells (PBDC), to ascertain feasibility, evaluate toxicity and assess induction of ESO-specific immune responses.

PATIENTS & METHODS

Eligible participants had resected cancers expressing ESO or LAGE-1 and were at high risk of relapse. PBDC were produced using CliniMACS^®plus, with initial depletion of CD1c⁺ B cells followed by positive selection of CD1c⁺ PBDC. Patients received three intradermal vaccinations of ESO/IMX-pulsed PBDC at 4-week intervals.

RESULTS

The process was feasible and safe. No vaccine-induced immune responses were detected. Assays of immunomodulatory cells did not correlate with outcomes. One patient had a long lasting complete remission.

CONCLUSION

This method was feasible and safe but was minimally immunogenic.

Mycoplasma Infection Alters Cancer Stem Cell Properties in Vitro

Cancer cell lines can be useful to model cancer stem cells. Infection with Mycoplasma species is an insidious problem in mammalian cell culture. While investigating stem-like properties in early passage melanoma cell lines, we noted poorly reproducible results from an aliquot of a cell line that was later found to be infected with Mycoplasma hyorhinis. Deliberate infection of other early passage melanoma cell lines aliquots induced variable and unpredictable effects on expression of putative cancer stem cell markers, clonogenicity, proliferation and global gene expression. Cell lines established in stem cell media (SCM) were equally susceptible. Mycoplasma status is rarely reported in publications using cultured cells to study the cancer stem cell hypothesis. Our work highlights the importance of surveillance for Mycoplasma infection while using any cultured cells to interrogate tumor heterogeneity.

Optimizing combination dabrafenib and trametinib therapy in BRAF mutation-positive advanced melanoma patients: Guidelines from Australian melanoma medical oncologists

BRAF mutations occur commonly in metastatic melanomas and inhibition of mutant BRAF and the downstream kinase MEK results in rapid tumor regression and prolonged survival in patients. Combined therapy with BRAF and MEK inhibition improves response rate, progression free survival and overall survival compared with single agent BRAF inhibition, and reduces the skin toxicity that is seen with BRAF inhibitor monotherapy. However, this combination is associated with an increase in other toxicities, particularly drug-related pyrexia, which affects approximately 50% of patients treated with dabrafenib and trametinib (CombiDT). We provide guidance on managing adverse events likely to arise during treatment with combination BRAF and MEK inhibition with CombiDT: pyrexia, skin conditions, fatigue; and discuss management of CombiDT during surgery and radiotherapy. By improving tolerability and in particular preventing unnecessary treatment cessations or reduction in drug exposure, best outcomes can be achieved for patients undergoing CombiDT therapy.