Standard-dose pembrolizumab in combination with reduced-dose ipilimumab for patients with advanced melanoma (KEYNOTE-029): an open-label, phase 1b trial.

BACKGROUND: Reduced-dose nivolumab in combination with standard-dose ipilimumab improves objective response and progression-free survival compared with standard-dose ipilimumab alone, but increases toxicity. We assessed the safety and anti-tumour activity of standard-dose pembrolizumab in combination with reduced-dose ipilimumab. METHODS: In this open-label, phase 1b trial, we recruited patients from 12 medical centres in Australia, New Zealand, and the USA. Eligible patients were aged at least 18 years, had advanced melanoma, had an Eastern Coooperative Oncology Group performance status of 0 or 1, had measurable disease according to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, had adequate organ function, had resolution of toxic effects of the most recent previous chemotherapy to grade 1 or less, had no active autoimmune disease requiring systemic steroids or immunosuppressive agents, had no active non-infectious pneumonitis, had no uncontrolled thyroid dysfunction or diabetes, had no active brain metastases, and had not received previous immune checkpoint inhibitor therapy. Patients received intravenous pembrolizumab 2 mg/kg plus intravenous ipilimumab 1 mg/kg every 3 weeks for four doses, followed by intravenous pembrolizumab 2 mg/kg every 3 weeks for up to 2 years or disease progression, intolerable toxicity, withdrawal of consent, or investigator decision. The primary endpoint was safety and tolerability. The proportion of patients achieving an objective response assessed per RECIST version 1.1 by independent central review and overall survival were secondary endpoints. We also assessed progression-free survival. The primary endpoint was assessed in all patients who received at least one dose of combination therapy. Activity was assessed in all enrolled patients. This trial is registered with ClinicalTrials.gov, number NCT02089685. Enrolment into this cohort is closed, but patients are still being monitored for safety and anti-tumour activity. FINDINGS: Between Jan 13, 2015, and Sept 17, 2015, we enrolled and treated 153 patients. As of the Oct 17, 2016, cutoff date, median follow-up was 17·0 months (IQR 14·8-18·8). 110 (72%) of 153 patients received all four pembrolizumab plus ipilimumab doses; 64 (42%) remained on pembrolizumab monotherapy. 110 grade 3-4 treatment-related adverse events occurred in 69 (45%) patients. No treatment-related deaths occurred. Treatment-related adverse events led to discontinuation of pembrolizumab and ipilimumab in 22 (14%) patients, including 17 (11%) who discontinued both treatments for the same event and five (3%) who discontinued ipilimumab for one event and later discontinued pembrolizumab for another. 12 (8%) patients discontinued ipilimumab only and 14 (9%) discontinued pembrolizumab only because of treatment-related adverse events. 158 immune-mediated adverse events of any grade occurred in 92 (60%) patients, and 50 immune-mediated adverse events of grade 3-4 occurred in 42 (27%) patients; the most common immune-mediated adverse events were hypothyroidism (25 [16%]) and hyperthyroidism (17 [11%]). 93 (61% [95% CI 53-69]) patients achieved an objective response. Estimated 1 year progression-free survival was 69% (95% CI 60-75), and estimated 1 year overall survival was 89% (95% CI 83-93). INTERPRETATION: Standard-dose pembrolizumab given in combination with four doses of reduced-dose ipilimumab followed by standard-dose pembrolizumab has a manageable toxicity profile and provides robust anti-tumour activity in patients with advanced melanoma. These data suggest that standard-dose pembrolizumab plus reduced-dose ipilimumab might be a tolerable, efficacious treatment option for patients with advanced melanoma. A randomised phase 2 trial of alternative dosing strategies of this combination is underway. FUNDING: Merck & Co, Inc.

Systems analysis identifies miR-29b regulation of invasiveness in melanoma.

BACKGROUND: In many cancers, microRNAs (miRs) contribute to metastatic progression by modulating phenotypic reprogramming processes such as epithelial-mesenchymal plasticity. This can be driven by miRs targeting multiple mRNA transcripts, inducing regulated changes across large sets of genes. The miR-target databases TargetScan and DIANA-microT predict putative relationships by examining sequence complementarity between miRs and mRNAs. However, it remains a challenge to identify which miR-mRNA interactions are active at endogenous expression levels, and of biological consequence. METHODS: We developed a workflow to integrate TargetScan and DIANA-microT predictions into the analysis of data-driven associations calculated from transcript abundance (RNASeq) data, specifically the mutual information and Pearson's correlation metrics. We use this workflow to identify putative relationships of miR-mediated mRNA repression with strong support from both lines of evidence. Applying this approach systematically to a large, published collection of unique melanoma cell lines - the Ludwig Melbourne melanoma (LM-MEL) cell line panel - we identified putative miR-mRNA interactions that may contribute to invasiveness. This guided the selection of interactions of interest for further in vitro validation studies. RESULTS: Several miR-mRNA regulatory relationships supported by TargetScan and DIANA-microT demonstrated differential activity across cell lines of varying matrigel invasiveness. Strong negative statistical associations for these putative regulatory relationships were consistent with target mRNA inhibition by the miR, and suggest that differential activity of such miR-mRNA relationships contribute to differences in melanoma invasiveness. Many of these relationships were reflected across the skin cutaneous melanoma TCGA dataset, indicating that these observations also show graded activity across clinical samples. Several of these miRs are implicated in cancer progression (miR-211, -340, -125b, -221, and -29b). The specific role for miR-29b-3p in melanoma has not been well studied. We experimentally validated the predicted miR-29b-3p regulation of LAMC1 and PPIC and LASP1, and show that dysregulation of miR-29b-3p or these mRNA targets can influence cellular invasiveness in vitro. CONCLUSIONS: This analytic strategy provides a comprehensive, systems-level approach to identify miR-mRNA regulation in high-throughput cancer data, identifies novel putative interactions with functional phenotypic relevance, and can be used to direct experimental resources for subsequent experimental validation. Computational scripts are available: http://github.com/uomsystemsbiology/LMMEL-miR-miner.

NY-ESO-1 specific antibody and cellular responses in melanoma patients primed with NY-ESO-1 protein in ISCOMATRIX and boosted with recombinant NY-ESO-1 fowlpox virus.

Vaccination strategies based on repeated injections of NY-ESO-1 protein formulated in ISCOMATRIX particles (NY-ESO-1 ISCOMATRIX) have shown to elicit combined NY-ESO-1 specific antibody and T cell responses. However, it remains unclear whether heterologous prime-boost strategies based on the combination with NY-ESO-1 ISCOMATRIX with different NY-ESO-1 boosting reagents could be used to increase NY-ESO-1 CD8(+) or CD4(+) T cell responses. To address this question, we carried out a randomized clinical trial in 39 high-risk, resected melanoma patients vaccinated with NY-ESO-1 ISCOMATRIX, and then boosted with repeated injections of either recombinant fowlpox virus encoding full length NY-ESO-1 (rF-NY-ESO-1) (Arm A) or NY-ESO-1 ISCOMATRIX alone (Arm B). We have comprehensively analyzed NY-ESO-1 specific T cells and B cells response in all patients before and after vaccination for a total of seven time points per patient. NY-ESO-1 ISCOMATRIX alone elicited a strong NY-ESO-1 specific CD4(+) T cell and antibody response, which was maintained by both regiments at similar levels. However, CD8(+) T cell responses were significantly boosted in 3 out of 18 patients in Arm A after the first rF-NY-ESO-1 injection and such responses were maintained until the end of the trial, while no patients in Arm B showed similar CD8(+) T cell responses. In addition, our results clearly identified immunodominant regions in the NY-ESO-1 protein: NY-ESO-179-102 and NY-ESO-1115-138 for CD4+ T cells and NY-ESO-185-108 for CD8+ T cells in a large proportion of vaccinated patients. These regions of NY-ESO-1 protein should be considered in future clinical trials as immunodominant epitopes.

Standard-Dose Pembrolizumab Plus Alternate-Dose Ipilimumab in Advanced Melanoma: KEYNOTE-029 Cohort 1C, a Phase 2 Randomized Study of Two Dosing Schedules.

PURPOSE: Standard-dose pembrolizumab plus alternative-dose ipilimumab (1 mg/kg Q3W for 4 doses) were tolerable and had robust antitumor activity in advanced melanoma in cohort B of the phase 1 KEYNOTE-029 study. Cohort C evaluated standard-dose pembrolizumab with two other alternative ipilimumab regimens. PATIENTS AND METHODS: Patients with treatment-naive unresectable stage III/IV melanoma were randomly assigned 1:1 to pembrolizumab 200 mg Q3W for ≤24 months plus ipilimumab 50 mg Q6W for 4 doses (PEM200+IPI50), or the same pembrolizumab regimen plus ipilimumab 100 mg Q12W for 4 doses (PEM200+IPI100). Primary end points were incidence of grade 3-5 treatment-related adverse events (TRAE) and objective response rate (ORR) per RECIST v1.1 by independent central review. Per protocol-defined thresholds, grade 3-5 TRAE incidence ≤26% indicated meaningful toxicity reduction and ORR ≥48% indicated no decrease in efficacy versus data reported for other PD-1 inhibitor/ipilimumab combinations. RESULTS: Median follow-up on February 18, 2019, was 16.3 months in PEM200+IPI50 (N = 51) and 16.4 months in PEM200+IPI100 (N = 51). Grade 3-5 TRAEs occurred in 12 (24%) patients in PEM200+IPI50 and 20 (39%) in PEM200+IPI100. One patient in PEM200+IPI50 died from treatment-related autoimmune myocarditis. Immune-mediated AEs or infusion reactions occurred in 21 (42%) patients in PEM200+IPI50 and 28 (55%) in PEM200+IPI100. ORR was 55% in PEM200+IPI50; 61% in PEM200+IPI100. CONCLUSIONS: Pembrolizumab 200 mg Q3W plus ipilimumab 50 mg Q6W or 100 mg Q12W demonstrated antitumor activity above the predefined threshold; pembrolizumab plus ipilimumab 50 mg Q6W had lower incidence of grade 3-5 TRAEs than the predefined threshold, suggesting a reduction in toxicity. See related commentary by Jameson-Lee and Luke, p. 5153.

Distinctive Subpopulations of Stromal Cells Are Present in Human Lymph Nodes Infiltrated with Melanoma.

Metastasis of human tumors to lymph nodes (LN) is a universally negative prognostic factor. LN stromal cells (SC) play a crucial role in enabling T-cell responses, and because tumor metastases modulate their structure and function, this interaction may suppress immune responses to tumor antigens. The SC subpopulations that respond to infiltration of malignant cells into human LNs have not been defined. Here, we identify distinctive subpopulations of CD90+ SCs present in melanoma-infiltrated LNs and compare them with their counterparts in normal LNs. The first population (CD90+ podoplanin+ CD105+ CD146+ CD271+ VCAM-1+ ICAM-1+ α-SMA+) corresponds to fibroblastic reticular cells that express various T-cell modulating cytokines, chemokines, and adhesion molecules. The second (CD90+ CD34+ CD105+ CD271+) represents a novel population of CD34+ SCs embedded in collagenous structures, such as the capsule and trabeculae, that predominantly produce extracellular matrix. We also demonstrated that these two SC subpopulations are distinct from two subsets of human LN pericytes, CD90+ CD146+ CD36+ NG2- pericytes in the walls of high endothelial venules and other small vessels, and CD90+ CD146+ NG2+ CD36- pericytes in the walls of larger vessels. Distinguishing between these CD90+ SC subpopulations in human LNs allows for further study of their respective impact on T-cell responses to tumor antigens and clinical outcomes.

Spliced Peptides and Cytokine-Driven Changes in the Immunopeptidome of Melanoma.

Antigen recognition by CD8+ T cells is governed by the pool of peptide antigens presented on the cell surface in the context of HLA class I complexes. Studies have shown not only a high degree of plasticity in the immunopeptidome, but also that a considerable fraction of all presented peptides is generated through proteasome-mediated splicing of noncontiguous regions of proteins to form novel peptide antigens. Here, we used high-resolution mass spectrometry combined with new bioinformatic approaches to characterize the immunopeptidome of melanoma cells in the presence or absence of IFNγ. In total, we identified more than 60,000 peptides from a single patient-derived cell line (LM-MEL-44) and demonstrated that IFNγ induced changes in the peptidome, with an overlap of only approximately 50% between basal and treated cells. Around 6% to 8% of the peptides were identified as cis-spliced peptides, and 2,213 peptides (1,827 linear and 386 cis-spliced peptides) were derived from known melanoma-associated antigens. These peptide antigens were equally distributed between the constitutive- and IFNγ-induced peptidome. We next examined additional HLA-matched patient-derived cell lines to investigate how frequently these peptides were identified and found that a high proportion of both linear and spliced peptides was conserved between individual patient tumors, drawing on data amassing to more than 100,000 peptide sequences. Several of these peptides showed in vitro immunogenicity across multiple patients with melanoma. These observations highlight the breadth and complexity of the repertoire of immunogenic peptides that can be exploited therapeutically and suggest that spliced peptides are a major class of tumor antigens.

Long-term Follow-up of Standard-Dose Pembrolizumab Plus Reduced-Dose Ipilimumab in Patients with Advanced Melanoma: KEYNOTE-029 Part 1B.

PURPOSE: Combination therapy with reduced-dose programmed death 1 inhibitor plus standard-dose cytotoxic T-lymphocyte-associated antigen 4 inhibitor demonstrated efficacy, but substantial toxicity, in melanoma. We present long-term results of part 1B of KEYNOTE-029, which assessed safety and efficacy of standard-dose pembrolizumab plus reduced-dose ipilimumab in advanced melanoma. PATIENTS AND METHODS: Part 1B was an expansion cohort of the open-label, phase Ib portion of KEYNOTE-029. Eligible patients had advanced melanoma and no previous immune checkpoint inhibitor therapy. Patients received pembrolizumab 2 mg/kg (amended to 200 mg) every 3 weeks plus ipilimumab 1 mg/kg every 3 weeks (four cycles), then pembrolizumab alone for up to 2 years. Primary end point was safety; secondary end points included objective response rate (ORR), progression-free survival (PFS), duration of response (DOR), and overall survival (OS). RESULTS: A total of 153 patients received at least one dose of pembrolizumab plus ipilimumab. At a median follow-up of 36.8 months, 71.9% had received four doses of ipilimumab and 30.7% had completed 2 years of pembrolizumab; 26.1% completed both treatments. Treatment-related adverse events occurred in 96.1% (47.1% grade 3/4; no deaths), leading to discontinuation of one or both study drugs in 35.9%. ORR was 62.1% with 42 (27.5%) complete and 53 (34.6%) partial responses. Median DOR was not reached; 36-month ongoing response rate was 84.2%. Median PFS and OS were not reached; 36-month rates were 59.1% and 73.4%, respectively. CONCLUSIONS: Standard-dose pembrolizumab plus reduced-dose ipilimumab demonstrated robust antitumor activity, durable response, and favorable long-term survival with manageable toxicity.

Results of a randomized, double-blind phase II clinical trial of NY-ESO-1 vaccine with ISCOMATRIX adjuvant versus ISCOMATRIX alone in participants with high-risk resected melanoma.

BACKGROUND: To compare the clinical efficacy of New York Esophageal squamous cell carcinoma-1 (NY-ESO-1) vaccine with ISCOMATRIX adjuvant versus ISCOMATRIX alone in a randomized, double-blind phase II study in participants with fully resected melanoma at high risk of recurrence. METHODS: Participants with resected stage IIc, IIIb, IIIc and IV melanoma expressing NY-ESO-1 were randomized to treatment with three doses of NY-ESO-1/ISCOMATRIX or ISCOMATRIX adjuvant administered intramuscularly at 4-week intervals, followed by a further dose at 6 months. Primary endpoint was the proportion free of relapse at 18 months in the intention-to-treat (ITT) population and two per-protocol populations. Secondary endpoints included relapse-free survival (RFS) and overall survival (OS), safety and NY-ESO-1 immunity. RESULTS: The ITT population comprised 110 participants, with 56 randomized to NY-ESO-1/ISCOMATRIX and 54 to ISCOMATRIX alone. No significant toxicities were observed. There were no differences between the study arms in relapses at 18 months or for median time to relapse; 139 vs 176 days (p=0.296), or relapse rate, 27 (48.2%) vs 26 (48.1%) (HR 0.913; 95% CI 0.402 to 2.231), respectively. RFS and OS were similar between the study arms. Vaccine recipients developed strong positive antibody responses to NY-ESO-1 (p≤0.0001) and NY-ESO-1-specific CD4+ and CD8+ responses. Biopsies following relapse did not demonstrate differences in NY-ESO-1 expression between the study populations although an exploratory study demonstrated reduced (NY-ESO-1)+/Human Leukocyte Antigen (HLA) class I+ double-positive cells in biopsies from vaccine recipients performed on relapse in 19 participants. CONCLUSIONS: The vaccine was well tolerated, however, despite inducing antigen-specific immunity, it did not affect survival endpoints. Immune escape through the downregulation of NY-ESO-1 and/or HLA class I molecules on tumor may have contributed to relapse.

Predicting clinical outcome through molecular profiling in stage III melanoma.

PURPOSE: Patients with macroscopic stage III melanoma represent a heterogeneous cohort with average 5-year overall survival rates of <30%. With current algorithms, it is not possible to predict which patients will achieve longer-term survival. We hypothesized that molecular profiling could be used to identify prognostic groups within patients with stage III melanoma while also providing a greater understanding of the biological programs underpinning these differences. EXPERIMENTAL DESIGN: Lymph node sections from 29 patients with stage IIIB and IIIC melanoma, with divergent clinical outcome including 16 "poor-prognosis" and 13 "good-prognosis" patients as defined by time to tumor progression, were subjected to molecular profiling using oligonucleotide arrays as an initial training set. Twenty-one differentially expressed genes were validated using quantitative PCR and the 15 genes with strongest cross-platform correlation were used to develop two predictive scores, which were applied to two independent validation sets of 10 and 14 stage III tumor samples. RESULTS: Supervised analysis using differentially expressed genes was able to differentiate the prognostic groups in the training set. The developed predictive scores correlated directly with clinical outcome. When the predictive scores were applied to the two independent validation sets, clinical outcome was accurately predicted in 90% and 85% of patients, respectively. CONCLUSION: We describe a gene expression profile that is capable of distinguishing clinical outcomes in a previously homogeneous group of stage III melanoma patients.

ECSA/DPPA2 is an embryo-cancer antigen that is coexpressed with cancer-testis antigens in non-small cell lung cancer.

PURPOSE: Cancer cells recapitulate many behaviors of pluripotent embryonic cells such as unlimited proliferation, and the capacity to self-renew and to migrate. Embryo-cancer sequence A (ECSA), later named developmental pluripotency associated-2 (DPPA2), is an embryonic gene initially isolated from pluripotent human preimplantation embryos. We hypothesized that ECSA/DPPA2 would be quiescent in most normal tissues but expressed in cancers and may therefore be a useful target for immunotherapy. EXPERIMENTAL DESIGN: ECSA/DPPA2 expression was examined in a panel of normal and tumor tissue by reverse transcription PCR, quantitative real-time PCR, and immunohistochemistry. A panel of 110 non-small cell lung cancers (NSCLC) were further investigated for the presence of ECSA/DPPA2 transcripts and several cancer testis antigens (CTA). Sera from 104 patients were analyzed for spontaneous ECSA/DPPA2 antibody production by ELISA and Western blot. RESULTS: ECSA/DPPA2 transcripts were limited to normal testis, placenta, bone marrow, thymus, and kidney but expressed in a variety of tumors most notably in 30% of NSCLC. Enrichment for CTAs in ECSA/DPPA2-positive NSCLC was observed. Immunohistochemistry confirmed nuclear and cytoplasmic localization in subpopulations of cells with coexpression of the CTA MAGE-A3. Antibodies to recombinant ECSA/DPPA2 protein were detected in the sera of 4 of 104 patients with NSCLC but not in healthy controls. CONCLUSIONS: The restricted expression in normal tissues, expression in tumors with coexpression of CTAs, and spontaneous immunogenicity indicate that ECSA/DPPA2 is a promising target for antigen-specific immunotherapy in NSCLC.

Desmoplastic melanoma: comparison of expression of differentiation antigens and cancer testis antigens.

Desmoplastic melanoma is a diagnostic and therapeutic challenge. Immunohistochemical analysis with antibodies to melanoma antigens can complement morphologic evaluation. Although staining for S100 protein is generally positive, staining for other melanoma differentiation antigens, particularly gp100, Melan-A/MART1 and tyrosinase, is often negative despite being commonly positive in other melanoma types. A high clinical index of suspicion and better diagnostic techniques are essential as atypical features and incorrect diagnosis can lead to poor clinical outcomes. Antigens associated with melanoma, such as the melanocyte differentiation and cancer testis antigen, may become important targets for immune therapies. We characterized the patterns of antigen expression of desmoplastic melanoma from 32 patients, including gp100, Melan-A/MART-1, tyrosinase, MAGE-A1, MAGE-A4 and NY-ESO-1. Consistent positive staining with S100 was observed. Differentiation antigens were expressed more frequently than cancer testis antigens regardless of the histological subtype of desmoplastic melanoma. When present, cancer testis antigen expression correlated to positive staining with differentiation antigens. The diagnostic yield of desmoplastic melanoma did not increase with the addition of cancer testis antigen typing. Low levels of expression of cancer testis antigen may indicate that they are suboptimal targets for vaccine development in desmoplastic melanoma.

A phase I trial of humanized monoclonal antibody A33 in patients with colorectal carcinoma: biodistribution, pharmacokinetics, and quantitative tumor uptake.

PURPOSE: To determine the in vivo characteristics of huA33, a CDR-grafted humanized antibody against the A33 antigen, we have conducted an open-label, dose escalation, biopsy-based phase I trial of huA33 in patients with colorectal carcinoma. EXPERIMENTAL DESIGN: Patients with colorectal carcinoma were infused with [131I]huA33 (400 MBq: 10 mCi) and [125I]huA33 (40 MBq: 1 mCi) 1 week before surgery. There were four huA33 dose levels (0.25, 1.0, 5.0, and 10 mg/m2). Adverse events, pharmacokinetics, biodistribution, tumor biopsies, and immune responses to huA33 were evaluated. RESULTS: There were 12 patients entered into the trial (6 males and 6 females; age range, 39-66 years). No dose-limiting toxicity was observed. The biodistribution of huA33 showed excellent uptake of [131I]huA33 in metastatic colorectal carcinoma. Pharmacokinetic analysis showed no significant difference in terminal half-life (T1/2beta) between dose levels (mean +/- SD, 86.92 +/- 22.12 hours). Modeling of colon uptake of huA33 showed a T1/2 of elimination of 32.4 +/- 8.1 hours. Quantitative tumor uptake ranged from 2.1 x 10(-3) to 11.1 x 10(-3) %ID/g, and tumor/normal tissue and tumor/serum ratios reached as high as 16.3:1 and 4.5:1, respectively. Biosensor analysis detected low-level human anti-human antibody responses in four patients following huA33 infusion. CONCLUSIONS: huA33 shows selective and rapid localization to colorectal carcinoma in vivo and penetrates to the center of large necrotic tumors, and colon elimination half-life of huA33 is equivalent to basal colonocyte turnover. The excellent targeting characteristics of this humanized antibody indicate potential for the targeted therapy of metastatic colorectal cancer in future trials.

Phase I trial of 131I-huA33 in patients with advanced colorectal carcinoma.

PURPOSE: Humanized monoclonal antibody A33 (huA33) targets the A33 antigen which is expressed on 95% of colorectal cancers. A previous study has shown excellent tumor-targeting of iodine-131 labeled huA33 (131I-huA33). Therefore, we did a phase I dose escalation trial of 131I-huA33 radioimmunotherapy. EXPERIMENTAL DESIGNS: Fifteen patients with pretreated metastatic colorectal carcinoma each received two i.v. doses of 131I-huA33. The first was an outpatient trace-labeled "scout" dose for biodistribution assessment, followed by a second "therapy" dose. Three patients were treated at 20, 30, and 40 mCi/m2 dose levels, and six patients at 50 mCi/m2 to define the maximum tolerated dose. RESULTS: Hematologic toxicity was 131I dose-dependent, with one episode of grade 4 neutropenia and two episodes of grade 3 thrombocytopenia observed at 50 mCi/m2. The maximum tolerated dose was determined to be 40 mCi/m2. There were no acute infusion-related adverse events, and gastrointestinal toxicity was not observed despite uptake of 131I-huA33 in bowel. Seven patients developed pruritus or rash, which was not related to 131I dose. There was excellent tumor-targeting of 131I-huA33 shown in all patients. The serum T1/2beta of 131I-huA33 was (mean +/- SD) 135.2 +/- 46.9 hours. The mean absorbed tumor dose was 6.49 +/- 2.47 Gy/GBq. Four patients developed human anti-human antibodies. At restaging, 4 patients had stable disease, whereas 11 patients had progressive disease. CONCLUSION: Radioimmunotherapy using 131I-huA33 shows promise in targeting colorectal tumors, and is deliverable at a maximum tolerated dose of 40 mCi/m2. Further studies of 131I-huA33 in combination with chemotherapy are planned.

Altered Expression and Splicing of ESRP1 in Malignant Melanoma Correlates with Epithelial-Mesenchymal Status and Tumor-Associated Immune Cytolytic Activity.

Melanoma is one of the major cancer types for which new immune-based cancer treatments have achieved promising results. However, anti-PD-1 and anti-CTLA-4 therapies are effective only in some patients. Hence, predictive molecular markers for the development of clinical strategies targeting immune checkpoints are needed. Using The Cancer Genome Atlas (TCGA) RNAseq data, we found that expression of ESRP1, encoding a master splicing regulator in the epithelial-mesenchymal transition (EMT), was inversely correlated with tumor-associated immune cytolytic activity. That association holds up across multiple TCGA tumor types, suggesting a link between tumor EMT status and infiltrating lymphocyte activity. In melanoma, ESRP1 mainly exists in a melanocyte-specific truncated form transcribed from exon 13. This was validated by analyzing CCLE cell line data, public CAGE data, and RT-PCR in primary cultured melanoma cell lines. Based on ESRP1 expression, we divided TCGA melanoma cases into ESRP1-low, -truncated, and -full-length groups. ESRP1-truncated tumors comprise approximately two thirds of melanoma samples and reside in an apparent transitional state between epithelial and mesenchymal phenotypes. ESRP1 full-length tumors express epithelial markers and constitute about 5% of melanoma samples. In contrast, ESRP1-low tumors express mesenchymal markers and are high in immune cytolytic activity as well as PD-L2 and CTLA-4 expression. Those tumors are associated with better patient survival. Results from our study suggest a path toward the use of ESRP1 and other EMT markers as informative biomarkers for immunotherapy. Cancer Immunol Res; 4(6); 552-61. ©2016 AACR.

Impact of 2-deoxy-2[F-18]fluoro-D-glucose Positron Emission Tomography on the management of patients with advanced melanoma.

OBJECTIVES: Accurate staging of patients with melanoma is vital to guide appropriate treatment. 2-Deoxy-2-[F-18]fluoro-D-glucose (FDG)-positron emission tomography (PET) has been reported to be a sensitive and specific technique for the staging of advanced melanoma, however, few studies provide information regarding its impact on patient management. METHODS: We retrospectively reviewed the FDG-PET scan results of 92 patients with melanoma who had 126 scans performed over a six-year period. These patients were seen at the specialist melanoma clinic at our Institution, and 84 patients (92%) had stage III or IV disease. FDG-PET scan results were correlated with computed tomography (CT) scans and other imaging when available, and with clinical follow-up of a minimum of three to six months. The impact of FDG-PET scans on patient management was also assessed. RESULTS: On a lesion-by-lesion analysis, FDG-PET had a sensitivity of 92%, a specificity of 88%, and an accuracy of 91%. FDG-PET correctly affected the clinical decision-making process in 40 of 126 patient studies (32%), particularly assisting in the selection of patients for surgery. CONCLUSION: FDG-PET has an important role in guiding the management of patients with advanced melanoma, particularly when surgery is contemplated.

The kinase inhibitors dabrafenib and trametinib affect isolated immune cell populations.

Metastatic melanoma is frequently fatal. Optimal treatment regimens require both rapid and durable disease control, likely best achieved by combining targeted agents with immunotherapeutics. In order to accomplish this, a detailed understanding of the immune consequences of the kinase inhibitors used to treat melanoma is required.

A single-centre experience of patients with metastatic melanoma enrolled in a dabrafenib named patient programme.

We studied the efficacy, tolerability and clinical courses of dabrafenib in patients with metastatic melanoma who were ineligible for enrolment into a clinical trial. Between July 2011 and May 2013, patients with unresectable stage III or stage IV, V600-mutated metastatic melanoma who were not eligible for inclusion into clinical trials were offered treatment with dabrafenib through a named patient programme. Routine efficacy and toxicity data were collected throughout treatment and studied retrospectively. The endpoints were progression-free survival (PFS), overall survival and best overall response. Thirty-one patients commenced dabrafenib therapy including six individuals who had progressed on a prior BRAF-inhibitor treatment. The majority of patients had cerebral metastases (n=17) and/or a poor performance status [Eastern Cooperative Oncology Group (ECOG)≥2, n=11]. Median overall survival was 5.6 months (range 0.1-22 months). Median PFS was 3.3 months (range 0.1-21) and was similar despite performance status. One patient had a complete response and eight showed partial responses to treatment. Patients with cerebral metastases (n=17) had a median PFS of 4.6 months. Five patients (16%) had dose-limiting toxicities. Despite several poor prognostic features, dabrafenib is a safe and effective treatment in the community setting, with occasional impressive outcomes.

MEK inhibition, alone or in combination with BRAF inhibition, affects multiple functions of isolated normal human lymphocytes and dendritic cells.

Combination therapy with BRAF and MEK inhibition is currently in clinical development for the treatment of BRAF-mutated malignant melanoma. BRAF inhibitors are associated with enhanced antigen-specific T-lymphocyte recognition in vivo. Consequently, BRAF inhibition has been proposed as proimmunogenic and there has been considerable enthusiasm for combining BRAF inhibition with immunotherapy. MEK inhibitors inhibit ERK phosphorylation regardless of BRAF mutational status and have been reported to impair T-lymphocyte and modulate dendritic cell function. In this study, we investigate the effects on isolated T lymphocytes and monocyte-derived dendritic cells (moDC) of a MEK (trametinib) and BRAF (dabrafenib) inhibitor combination currently being evaluated in a randomized controlled clinical trial. The effects of dabrafenib and trametinib, alone and in combination, were studied on isolated normal T lymphocytes and moDCs. Lymphocyte viability, together with functional assays including proliferation, cytokine production, and antigen-specific expansion, were assessed. MoDC phenotype in response to lipopolysaccharide stimulation was evaluated by flow cytometry, as were effects on antigen cross-presentation. Dabrafenib did not have an impact on T lymphocytes or moDCs, whereas trametinib alone or in combination with dabrafenib suppressed T-lymphocyte proliferation, cytokine production, and antigen-specific expansion. However, no significant decrease in CD4(+) or CD8(+) T-lymphocyte viability was observed following kinase inhibition. MoDC cross-presentation was suppressed in association with enhanced maturation following combined inhibition of MEK and BRAF. The results of this study demonstrate that MEK inhibition, alone or in combination with BRAF inhibition, can modulate immune cell function, and further studies in vivo will be required to evaluate the potential clinical impact of these findings.

BRAF/NRAS wild-type melanomas have a high mutation load correlating with histologic and molecular signatures of UV damage.

PURPOSE: The mutation load in melanoma is generally high compared with other tumor types due to extensive UV damage. Translation of exome sequencing data into clinically relevant information is therefore challenging. This study sought to characterize mutations identified in primary cutaneous melanomas and correlate these with clinicopathologic features. EXPERIMENTAL DESIGN: DNA was extracted from 34 fresh-frozen primary cutaneous melanomas and matched peripheral blood. Tumor histopathology was reviewed by two dermatopathologists. Exome sequencing was conducted and mutation rates were correlated with age, sex, tumor site, and histopathologic variables. Differences in mutations between categories of solar elastosis, pigmentation, and BRAF/NRAS mutational status were investigated. RESULTS: The average mutation rate was 12 per megabase, similar to published results in metastases. The average mutation rate in severely sun damaged (SSD) skin was 21 per Mb compared with 3.8 per Mb in non-SSD skin (P=0.001). BRAF/NRAS wild-type (WT) tumors had a higher average mutation rate compared with BRAF/NRAS-mutant tumors (27 vs. 5.6 mutations per Mb; P=0.0001). Tandem CC>TT/GG>AA mutations comprised 70% of all dinucleotide substitutions and were more common in tumors arising in SSD skin (P=0.0008) and in BRAF/NRAS WT tumors (P=0.0007). Targetable and potentially targetable mutations in WT tumors, including NF1, KIT, and NOTCH1, were spread over various signaling pathways. CONCLUSION: Melanomas arising in SSD skin have higher mutation loads and contain a spectrum of molecular subtypes compared with BRAF- and NRAS-mutant tumors indicating multigene screening approaches and combination therapies may be required for management of these patients.

Human perforin mutations and susceptibility to multiple primary cancers.

Loss-of-function mutations in the gene coding for perforin (PRF1) markedly reduce the ability of cytotoxic T lymphocytes and natural killer cells to kill target cells, causing immunosuppression and impairing immune regulation. In humans, nearly half of the cases of type 2 familial hemophagocytic lymphohistiocytosis are due to bi-allelic PRF1 mutations. The partial inactivation of PRF1 due to mutations that promote protein misfolding or the common hypomorphic allele coding for the A91V substitution have been associated with lymphoid malignancies in childhood and adolescence. To investigate whether PRF1 mutations also predispose adults to cancer, we genotyped 566 individuals diagnosed with melanoma (101), lymphoma (65), colorectal carcinoma (30) or ovarian cancer (370). The frequency of PRF1 genotypes was similar in all disease groups and 424 matched controls, indicating that the PRF1 status is not associated with an increased susceptibility to these malignancies. However, four out of 15 additional individuals diagnosed with melanoma and B-cell lymphoma during their lifetime expressed either PRF1A91V or the rare pathogenic PRF1R28C variant (p = 0.04), and developed melanoma relatively early in life. Both PRF1A91V- and PRF1R28C-expressing lymphocytes exhibited severely impaired but measurable cytotoxic function. Our results suggest that defects in human PRF1 predispose individuals to develop both melanoma and lymphoma. However, these findings require validation in larger patient cohorts.