Landscape Of Melanoma Research Articles

The A to I editing landscape in melanoma and its relation to clinical outcome

ABSTRACT RNA editing refers to non-transient RNA modifications that occur after transcription and prior to translation by the ribosomes. RNA editing is more widespread in cancer cells than in non-transformed cells and is associated with tumorigenesis of various cancer tissues. However, RNA editing can also generate neo-antigens that expose tumour cells to host immunosurveillance. Global RNA editing in melanoma and its relevance to clinical outcome currently remain poorly characterized. The present study compared RNA editing as well as gene expression in tumour cell lines from melanoma patients of short or long metastasis-free survival, patients relapsing or not after immuno- and targeted therapy and tumours harbouring BRAF or NRAS mutations. Overall, our results showed that NTRK gene expression can be a marker of resistance to BRAF and MEK inhibition and gives some insights of candidate genes as potential biomarkers. In addition, this study revealed an increase in Adenosine-to-Inosine editing in Alu regions and in non-repetitive regions, including the hyperediting of the MOK and DZIP3 genes in relapsed tumour samples during targeted therapy and of the ZBTB11 gene in NRAS mutated melanoma cells. Therefore, RNA editing could be a promising tool for identifying predictive markers, tumour neoantigens and targetable pathways that could help in preventing relapses during immuno- or targeted therapies.

Factors Determining Long-Term Antitumor Responses to Immune Checkpoint Blockade Therapy in Melanoma.

With the increasing promise of long-term survival with immune checkpoint blockade (ICB) therapies, particularly for patients with advanced melanoma, clinicians and investigators are driven to identify prognostic and predictive factors that may help to identify individuals who are likely to experience durable benefit. Several ICB combinations are being actively developed to expand the armamentarium of treatments for patients who may not achieve long-term responses to ICB single therapies alone. Thus, negative predictive markers are also of great interest. This review seeks to deepen our understanding of the mechanisms underlying the durability of ICB treatments. We will discuss the currently available long-term data from the ICB clinical trials and real-world studies describing the survivorship of ICB-treated melanoma patients. Additionally, we explore the current treatment outcomes in patients rechallenged with ICB and the patterns of ICB resistance based on sites of disease, namely, liver or CNS metastases. Lastly, we discuss the landscape in melanoma in the context of prognostic or predictive factors as markers of long-term response to ICB.

Immune-related lncRNA pairs as novel signature to predict prognosis and immune landscape in melanoma patients.

To investigate immune-related long non-coding RNA (irlncRNA) signatures for predicting survival and the immune landscape in melanoma patients.We retrieved gene expression files from The Cancer Genome Atlas and the Genotype-Tissue Expression database and extracted all the long non-coding RNAs from the original data. Then, we selected immune-related long non-coding RNAs (irlncRNAs) using co-expression networks and screened differentially expressed irlncRNAs (DEirlncRNAs) to form pairs. We also performed univariate analysis and Least absolute shrinkage and selection operator (LASSO) penalized regression analysis to identify prognostic DEirlncRNA pairs, constructed receiver operating characteristic curves, compared the areas under the curves, and calculated the optimal cut-off point to divide patients into high-risk and low-risk groups. Finally, we performed multivariate Cox regression analysis, Kaplan–Meier (K–M) survival analysis, clinical correlation analysis, and investigated correlations with tumor-infiltrating immune cells, chemotherapeutic effectiveness, and immunogene biomarkers.A total of 297 DEirlncRNAs were identified, of which 16 DEirlncRNA pairs were associated with prognosis in melanoma. After grouping patients by the optimal cut-off value, we could better distinguish melanoma patients with different survival outcomes, clinical characteristics, tumor immune status changes, chemotherapeutic drug sensitivity, and specific immunogene biomarkers.The DEirlncRNA pairs showed potential as novel biomarkers to predict the prognosis of melanoma patients. Furthermore, these DEirlncRNA pairs could be used to evaluate treatment efficacy in the future.

PARP Inhibitors in Melanoma-An Expanding Therapeutic Option?

Simple SummaryMelanomas with homologous recombination DNA damage repair pathways represent a subset of melanoma that may benefit from PARP inhibitors and immunotherapy. PARP inhibitors have an established role in treating cancers with underlying BRCA mutation through synthetic lethality; however, there is increasing evidence that it can be applied to a larger population including other types of homologous recombination defects. These gene mutations can be found in 20–40% of cutaneous melanoma. To date, PARP inhibitors and immunotherapy have been overlooked in the management of melanoma. This review explores the reasons for combining PARP inhibitors and immunotherapy. There is evidence to suggest that PARP inhibitors can improve the therapeutic effect of immune checkpoint inhibitors. Therefore, this combination approach has the potential to impact future treatment of patients with melanoma, particularly those with homologous recombination DNA damage repair defects. Immunotherapy has transformed the treatment landscape of melanoma; however, despite improvements in patient outcomes, monotherapy can often lead to resistance and tumour escape. Therefore, there is a need for new therapies, combination strategies and biomarker-guided decision making to increase the subset of patients most likely to benefit from treatment. Poly (ADP-ribose) polymerase (PARP) inhibitors act by synthetic lethality to target tumour cells with homologous recombination deficiencies such as BRCA mutations. However, the application of PARP inhibitors could be extended to a broad range of BRCA-negative cancers with high rates of DNA damage repair pathway mutations, such as melanoma. Additionally, PARP inhibition has the potential to augment the therapeutic effect of immunotherapy through multi-faceted immune-priming capabilities. In this review, we detail the immunological role of PARP and rationale for combining PARP and immune checkpoint inhibitors, with a particular focus on a subset of melanoma with homologous recombination defects that may benefit most from this targeted approach. We summarise the biology supporting this combined regimen and discuss preclinical results as well as ongoing clinical trials in melanoma which may impact future treatment.

Immune Monitoring in Melanoma and Urothelial Cancer Patients Treated with Anti-PD-1 Immunotherapy and SBRT Discloses Tumor Specific Immune Signatures.

Simple SummaryCurrently available biomarkers for response to checkpoint inhibitors are incomplete and predominantly focus on tumor tissue analysis e.g., tumor mutational burden, programmed cell death-ligand 1 (PD-L1) expression. Biomarkers in peripheral blood would allow a more dynamic monitoring and could offer a way for sequential adaptation of treatment strategy. We conducted an in-depth analysis of baseline and on-treatment systemic immune features in a cohort of stage III/IV melanoma and stage IV urothelial cancer (UC) patients treated with anti-programmed cell death-1 (anti-PD-1) therapy combined with stereotactic body radiotherapy (SBRT) in a similar regimen/schedule. Baseline immunity was clearly different between these two cohorts, indicating a less active immune landscape in UC patients. This study also detected signatures of proliferation in the CD8+ T-cell compartment pre-treatment and early after anti-PD-1 initiation that were positively correlated with clinical outcome in both tumor types. In addition our data support the biological relevance of PD-1/PD-L1 expression on circulating immune cell subsets, especially in melanoma.(1) Background: Blockade of the PD-1/PD-L1 pathway has revolutionized the oncology field in the last decade. However, the proportion of patients experiencing a durable response is still limited. In the current study, we performed an extensive immune monitoring in patients with stage III/IV melanoma and stage IV UC who received anti-PD-1 immunotherapy with SBRT. (2) Methods: In total 145 blood samples from 38 patients, collected at fixed time points before and during treatment, were phenotyped via high-parameter flow cytometry, luminex assay and UPLC-MS/MS. (3) Results: Baseline systemic immunity in melanoma and UC patients was different with a more prominent myeloid compartment and a higher neutrophil to lymphocyte ratio in UC. Proliferation (Ki67+) of CD8+ T-cells and of the PD-1+/PD-L1+ CD8+ subset at baseline correlated with progression free survival in melanoma. In contrast a higher frequency of PD-1/PD-L1 expressing non-proliferating (Ki67−) CD8+ and CD4+ T-cells before treatment was associated with worse outcome in melanoma. In UC, the expansion of Ki67+ CD8+ T-cells and of the PD-L1+ subset relative to tumor burden correlated with clinical outcome. (4) Conclusion: This study reveals a clearly different immune landscape in melanoma and UC at baseline, which may impact immunotherapy response. Signatures of proliferation in the CD8+ T-cell compartment prior to and early after anti-PD-1 initiation were positively correlated with clinical outcome in both cohorts. PD-1/PD-L1 expression on circulating immune cell subsets seems of clinical relevance in the melanoma cohort.

Risk Factors for Relapse after Intentional Discontinuation of Immune Checkpoint Inhibitors in Melanoma Patients.

Immune checkpoint inhibitors (ICIs) have tremendously changed the therapeutic landscape of melanoma since they are associated with a durable response, allowing for intentional discontinuation of therapy after complete or partial remission. However, a subset of patients develops a relapse after cessation of ICI treatment and may not respond to reinduction of ICIs. The aim of the present study was to identify risk factors for relapse after intentional discontinuation of ICI therapy. Patients with intentional discontinuation of ICI therapy for metastatic or unresectable melanoma from 5 German university hospitals were analyzed retrospectively. Clinicopathologic and follow-up data of 87 patients were collected and analyzed by univariate and multivariate Cox proportional-hazards models. The following parameters were associated with relapse after cessation of ICI treatment in the univariate Cox regression analysis: concurrent radiotherapy and ICI, best overall response, and presence of brain metastases. Duration of treatment, type of primary tumor, body mass index, programmed-death ligand 1 expression, and lactate dehydrogenase levels did not significantly influence the risk for relapse. In the multivariate analysis, partial remission [hazard ratio 4.217 (95% confidence interval: 1.424-12.49), P=0.009] and stable disease [3.327 (1.204-9.19), P=0.02] were associated with a significant decrease in progression-free survival compared with complete remission. Concurrent radiotherapy and ICI [3.619 (1.288-10.168), P=0.015] are additional independent risk factors for decreased progression-free survival upon ICI discontinuation, whereas the presence of brain metastasis did not reach statistical significance on multivariate analysis.

Genetic landscape of melanoma in China reveals enrichment of fusions in driver-negative melanoma.

e21577 Background: Melanoma in China has unique characteristics, especially compared with those in euramerican white race. In european and american countries, nearly 90% of melanoma patients are cutaneous melanoma; while 60% of melanoma in China are acral melanoma, accompanied with a considerable proportion of mucosal melanoma. Mapping the mutation landscape of melanoma in China can provide an important basis for targeted therapy of melanoma patients. Methods: Tissue samples from 223 patients with melanoma were sequenced using multi-gene NGS panel Onco PanScan to detect somatic mutations in melanoma. Results: As a result, BRAF (24.2%) and NRAS (15.7%) were the top two most mutated driver genes. In BRAF, V600E was the most common mutation, which accounted for 80% of all BRAF mutations. And Q61R/K was the most common mutation in NRAS, which accounted for 68.6% of all NRAS mutations. As to CNVs, the most frequently amplified genes were CCND1 (23, 10.3%), CDK4 (18, 8.1%), MDM2 (17, 7.6%), FGF19 (16, 7.2%), FGF4 (13, 5.8%), FGF3 (12, 5.4%), KIT (12, 5.4%), RICTOR (12, 5.4%). At the same time, a small number of EGFR, HER2, MET, MYC amplifications were detected. Interestingly, a considerable proportion of CNVs were related with hyperprogressive disease, including amplification of MDM2, CCND1, FGF3, FGF4, FGF19. Except for SNVs and CNVs, 16 gene fusions were detected in 13 samples (5.8%), among which the frequency of fusions involving BRAF, ALK, RAF1 was 2.2% (5/223), 1.3% (3/223) and 1% (2/223) respectively. Among these 16 fusions, only 4 fusions (AGAP3-BRAF, GTF2I-BRAF, TPM3-ALK, DCTN1-ALK) were reported previously, leaving the remaining 12 fusions new detected. As was reported, AGAP3-BRAF fusion was the mechanism by which melanoma patients with BRAF V600E mutations developed resistance to vemurafenib; GTF2I-BRAF fusion mediated the activation of MAPK pathway in fibrous astrocytoma. At last, we also compared the frequency of fusion detected in driver-positive and driver-negative melanoma (no somatic mutations detected in BRAF, HRAS, KRAS, NRAS, NF1, KIT, GNAQ, GNA11), and the result showed the frequency of fusion detected in driver-negative melanoma was significantly higher (9/78, 11.5% vs. 4/145, 2.8%). Conclusions: Through DNA-based NGS, the mutation landscape of Chinese melanoma patients was depicted. BRAF was the most frequently mutated driver gene with the main mutation type of V600E (19.7%) which was significantly lower than that of white race in TCGA-SKCM database (44.2%). On the other hand, DNA-based NGS can detect potentially druggable fusions, and compared with driver positive melanoma patients, fusions were enriched in patients with no driver mutations detected. Perhaps for driver negative melanoma patients, RNA-based NGS should be used to detect more potential druggable fusions which would bring clinical benefit.

Ensuring equity in the management of patients, over 70 years of age, on immunotherapy during the COVID-19 pandemic.

e21526 Background: Immunotherapy (IO) has transformed the landscape for melanoma. Checkpoint inhibitors (CPI) are now routinely given to older patients. The impact of performance status (PS) and age on the immune response remains unclear. During the COVID-19 pandemic, most older patients elected to continue their cancer therapy. Meta-analysis from trial data thus far has not demonstrated any association with cancer immunotherapy survival. This abstract reports on real –world experience of older patients with melanoma treated during the global pandemic. Methods: Real world data of all patients over 70 years of age receiving IO for melanoma, was collated at a tertiary cancer centre from Oct 2019 – Dec 2020. The objective was to see how these older patients tolerated CPI, in both the adjuvant and palliative settings, during a global pandemic. Information on demographics including age at diagnosis, intention, sites of metastases, PS, co-morbidities, toxicity, impact of COVID-19 and the patient outcomes were collected. During the pandemic the majority of patients on CPI treatment were assessed and followed up by telephone call rather than face to face. Results: Fifty-six patients over 70 years,were identified to have received CPI during the time period. There were 36 male and 22 female patients. Median age was 74 (range 70-88 years). Sixteen patients (29%) were treated with adjuvant intent; the remaining 40 patients (71%) were treated with palliative intent. Most patients with metastatic disease had 1-3 sites. All patients were PS0-1, except for one patient who was PS2. There were 19 patients (34%) who developed significant grade ¾ toxicities. No patients were treated on a clinical trial during the pandemic. Three patients (5%) elected to stop treatment during the pandemic. Calls to triage were taken as normal and the majority of patients had toxicity managed as an outpatient. No patients received the vaccine by the end of the study period. Conclusions: Real-world data explored the use of CPI in older patients and the impact of the COVID-19 pandemic on their management. Older patients were able to continue on CPI during the pandemic and it was given safely in adjuvant and palliative settings. Comprehensive geriatric assessments are planned to be integrated however the current demands on medical colleagues has delayed the introduction. However clinicians working in partnership with patients ensured the safe delivery and no patients died from toxicity of therapy or COVID-19 during this time. These findings suggest that shared decision-making during a pandemic with older patients is essential to support patients and optimise outcomes. We suggest cancer therapies should not be restricted to patients based on age and IO can be given safely if precautions are taken during a global pandemic. Patients have now received first COVID-19 vaccinations and ongoing assessement of the impact of the vaccination is in progress.

Tumor Immune Microenvironment Characterization Identifies Prognosis and Immunotherapy-Related Gene Signatures in Melanoma.

BackgroundThe tumor microenvironment (TME) involves infiltration of multiple immune cell subsets, which could influence the prognosis and clinical characteristics. The increasing evidence on the role of tumor-infiltrating lymphocytes (TILs) in primary and metastatic melanomas supports that the immune system is involved in the progression and outcomes of melanoma. However, the immune infiltration landscape in melanoma has not been systematically elucidated.MethodsIn this study, we used CIBERSORT and ESTIMATE algorithms to analyze immune infiltration pattern of 993 melanoma samples. Then we screened differential expression genes (DEGs) related to immune subtypes and survival. The immune cell infiltration (ICI) score was constructed by using principal-component analysis (PCA) based on immune signature genes from DGEs. Gene set enrichment analysis (GSEA) was applied to explore high and low ICI score related pathways. Finally, the predictive ability of ICI score was evaluated in survival prognosis and immunotherapy benefit.ResultWe identified three ICI clusters and three gene clusters associated with different immune subtypes and survival outcomes. Then the ICI score was constructed, and we found that high ICI score exhibited activated immune characteristics and better prognosis. High ICI score was significantly enriched in immune pathways and highly expressed immune signature genes. More importantly, we confirmed that melanoma patients with high ICI score had longer overall survival and rate of response to immunotherapy.ConclusionWe presented a comprehensive immune infiltration landscape in melanoma. Our results will facilitate understanding of the melanoma tumor microenvironment and provide a new immune therapy strategy.

Abstract 3946: Tumor checkpoint inhibitor profiling for an optimal clinical response

Abstract The last three decades have seen a steady rise in melanoma, the most aggressive form of skin cancer. The discovery of checkpoint inhibitors has revolutionized the treatment landscape for melanoma; anti-CTLA4 and anti-PD1 showing great successes in clinic. While checkpoint molecules and co-stimulatory molecules are traditionally present on cells involved in immune activation, mounting evidence suggests that tumor cells also express these molecules. Our laboratory has characterized five patient-derived melanoma cell lines, MEL-2, MEL-V, 3MM, KFM, and GLM-2 and screened them for the expression of a comprehensive list of 29 co-stimulatory and co-inhibitory molecules compared to normal adult melanocytes. We see a differential mRNA expression of many of these immune-regulatory molecules, including BTLA, HVEM, CD160, CD226 and TIM1. Western blots and immunofluorescence confirmed the presence of these molecules at the protein level. A flow cytometry analysis demonstrated that BTLA, HVEM, CD160, TIM1 and CD226 are present on the membrane of these patient derived melanoma cells; implying that they are capable of engaging their respective ligands and exerting a functional role in immunomodulation. These findings were additionally validated in melanoma tissues, obtained from patients, by immunohistochemistry. Interestingly, treatment of MEL-2, MEL-V, KFM and GLM-2, our BRAFV600E containing patient derived cells, with BRAFV600E inhibitor PLX4032 led to the upregulation of these molecules. This upregulation was coupled with an increase in transcription factor MITF, a binding site for which is present in the promoter region of all the upregulated molecules. Co-culture experiments with immune cells, demonstrate a modulatory role played by the HVEM/BTLA/CD160 axis molecules that are present on tumor cells. The presence of these additional immune-regulatory molecules signify the existence of a robust tolerance mechanism induced by these checkpoint inhibitors. Our studies underscore the importance of characterizing tumor profiles to enable the selection of an optimal treatment regimen combining targeted small molecule inhibitors, and checkpoint inhibitors to maximize T cell killing, and tumor clearance. Citation Format: Rachana R. Maniyar, Sanjukta Chakraborty, Ghada Ben Rahoma, John J. Degliuomini, Marc Wallack, Jan Geliebter, Raj K. Tiwari. Tumor checkpoint inhibitor profiling for an optimal clinical response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3946.

Abstract IA15: Treatment of non-V600-mutated BRAF melanoma: A role for combination MEK and CDK4/6 inhibition.

Abstract Targeting of the BRAFV600 mutation has proven a highly effective treatment strategy for the subset of melanoma carrying this mutation. However, the majority (~60%) of patients with advanced melanoma do not carry these mutations and are not targetable by selective BRAF inhibitors. The rapidly evolving genetic landscape of melanoma has revealed that the vast majority of non-V600 BRAF mutant melanoma still express other genomic alterations that lead to MAP kinase pathway activation. The most frequent of these are activating mutations in the NRAS gene representing 1/3 of the non-V600 BRAF mutant melanoma or 15-20% overall. The other MAPkinase activating genetic alteration include NF1 loss of function, MAP2K1, C-RAF, K- or H-RAS, and alternate -non-V600 mutations in the BRAF gene. Therefore MEK inhibitors, ERK inhibitors, or even non-selective RAF inhibitors may represent effective therapeutic interventions. Early results with MEK inhibitors in the NRAS mutant and non-NRAS or non-BRAF V600E mutant melanoma demonstrate clinical activity but likely not as robust as hoped. A trial with a MEK inhibitor (binmetinib) has demonstrated an unconfirmed objective response rate of approximately 20%. MEK inhibitors are also active against non-NRAS, non-BRAF V600 mutant melanoma including responses in those melanomas carrying mutations in BRAF gene outside of V600 codon. Genomic findings also demonstrate a high frequency of dysregulation of cell cycle regulatory proteins including genomic alterations in CDKN2A, CDK4, Cyclin D1, etc. This finding suggests a role for CDK4/6 inhibitors in the therapy of melanoma. Additionally, preclinical work has demonstrated the effectiveness of the combination of MEK inhibitors (trametinib, binimetinib) with CDK4/6 inhibitors (palbociclib, LEE011) in multiple mouse models of NRAS mutant melanoma. New, selective, and more effective CDK4/6 inhibitors have arrived in the clinic including palbociclib and LEE011 to name several, Based on this background clinical investigations have recently begun in non-BRAF V600 mutant melanomas with combination MEK inhibitor and CDK4/6 inhibitor treatment. While very early in their development, Binimetinib and LEE011 has already produced objective clinical responses in about 1/3 of NRAS mutant melanoma patients with another 1/3 demonstrating clinical responses not meeting RECIST 1.1 criteria. Most impressive is the rapid nature of these responses and in some cases accompanying relief from tumor-related symptoms. Early on some significant toxicities have been observed and alternate schedules are being explored. These regimens are also being evaluated in the non-NRAS mutant, non BRAF V600 mutant melanomas. As premature as these results are they still provide excitement that targeting mutations other than BRAFV600 is feasible and may provide hope for additional therapeutic options for the majority of melanoma patients. Note: This abstract was presented as part of the Joint Session: Clinical Science Interactions between Melanoma and Hematologic Malignancies with the AACR Special Conference on Advances in Melanoma: From Biology to Therapy held September 20-23, 2014 in Philadelphia, PA. Citation Format: Jeffrey A. Sosman. Treatment of non-V600-mutated BRAF melanoma: A role for combination MEK and CDK4/6 inhibition. [abstract]. In: Proceedings of the AACR Special Conference on Hematologic Malignancies: Translating Discoveries to Novel Therapies; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(17 Suppl):Abstract nr IA15.

Abstract IA13: Treatment of non-V600-mutated BRAF melanoma: A role for combination MEK and CDK4/6 inhibition

Abstract Targeting of the BRAFV600 mutation has proven a highly effective treatment strategy for the subset of melanoma carrying this mutation. However, the majority (∼60%) of patients with advanced melanoma do not carry these mutations and are not targetable by selective BRAF inhibitors. The rapidly evolving genetic landscape of melanoma has revealed that the vast majority of non-V600 BRAF mutant melanoma still express other genomic alterations that lead to MAP kinase pathway activation. The most frequent of these are activating mutations in the NRAS gene representing 1/3 of the non-V600 BRAF mutant melanoma or 15-20% overall. The other MAPkinase activating genetic alteration include NF1 loss of function, MAP2K1, C-RAF, K- or H-RAS, and alternate -non-V600 mutations in the BRAF gene. Therefore MEK inhibitors, ERK inhibitors, or even non-selective RAF inhibitors may represent effective therapeutic interventions. Early results with MEK inhibitors in the NRAS mutant and non-NRAS or non-BRAF V600E mutant melanoma demonstrate clinical activity but likely not as robust as hoped. A trial with a MEK inhibitor (binmetinib) has demonstrated an unconfirmed objective response rate of approximately 20%. MEK inhibitors are also active against non-NRAS, non-BRAF V600 mutant melanoma including responses in those melanomas carrying mutations in BRAF gene outside of V600 codon. Genomic findings also demonstrate a high frequency of dysregulation of cell cycle regulatory proteins including genomic alterations in CDKN2A, CDK4, Cyclin D1, etc. This finding suggests a role for CDK4/6 inhibitors in the therapy of melanoma. Additionally, preclinical work has demonstrated the effectiveness of the combination of MEK inhibitors (trametinib, binimetinib) with CDK4/6 inhibitors (palbociclib, LEE011) in multiple mouse models of NRAS mutant melanoma. New, selective, and more effective CDK4/6 inhibitors have arrived in the clinic including palbociclib and LEE011 to name several, Based on this background clinical investigations have recently begun in non-BRAF V600 mutant melanomas with combination MEK inhibitor and CDK4/6 inhibitor treatment. While very early in their development, Binimetinib and LEE011 has already produced objective clinical responses in about 1/3 of NRAS mutant melanoma patients with another 1/3 demonstrating clinical responses not meeting RECIST 1.1 criteria. Most impressive is the rapid nature of these responses and in some cases accompanying relief from tumor-related symptoms. Early on some significant toxicities have been observed and alternate schedules are being explored. These regimens are also being evaluated in the non-NRAS mutant, non BRAF V600 mutant melanomas. As premature as these results are they still provide excitement that targeting mutations other than BRAFV600 is feasible and may provide hope for additional therapeutic options for the majority of melanoma patients. Note: This abstract was presented as part of the Joint Session: Clinical Science Interactions between Melanoma and Hematologic Malignancies with the AACR Special Conference: Hematologic Malignancies: Translating Discoveries to Novel Therapies held September 20-23, 2014 in Philadelphia, PA. Citation Format: Jeffrey A. Sosman. Treatment of non-V600-mutated BRAF melanoma: A role for combination MEK and CDK4/6 inhibition. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Melanoma: From Biology to Therapy; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(14 Suppl):Abstract nr IA13.

MEK + CDK4 a regimen for non-BRAF V6000 melanoma

Targeting of the BRAFV600 mutation has proven a highly effective treatment strategy for the subset of melanoma carrying this mutation. However, the majority (~60%) of patients with advanced melanoma do not carry this mutation and are not targetable by selective BRAF inhibitors. The rapidly evolving genetic landscape of melanoma has revealed that the vast majority of non-V600 BRAF mutant melanoma still express other genomic alterations that lead to MAP kinase pathway activation. The most frequent of these are activating mutations in the NRAS gene representing 1/3 of the non-V600 BRAF mutant melanoma or 15-20% overall. The other MAPkinase activating genetic alteration include NF1 loss of function, MAP2K1, C-RAF, K- or H-RAS, and alternate -non-V600 mutations in the BRAF gene. Therefore MEK inhibitors, ERK inhibitors, or even non-selective RAF inhibitors may represent effective therapeutic interventions. Early results in the NRAS mutant and non-NRAS or BRAF V600E mutant melanoma demonstrate clinical activity but likely not as robust as hoped. A trial with a MEK inhibitor (binmetinib) has demonstrated an unconfirmed objective response rate of approximately 20%. MEK inhibitors are also active against non-NRAS, non-BRAF V600 mutant melanoma including responses in those melanomas carrying mutations in BRAF gene outside of V600 codon. Genomic findings also demonstrate a high frequency of dysregulation of cell cycle regulatory proteins including genomic alterations in CDKN2A, CDK4, Cyclin D1, etc. This finding suggests a role for CDK4/6 inhibitors in the therapy of melanoma. Additionally, preclinical work has demonstrated the effectiveness of the combination of MEK inhibitors (trametinib, binimetinib) with CDK4/6 inhibitors (palbociclib, LEE011) in multiple mouse models of NRAS mutant melanoma. New, selective, and more effective CDK4/6 inhibitors have arrived in the clinic including palbociclib and LEE011 to name several, Based on this background clinical investigations have recently begun in non-BRAF V600 mutant melanomas with combination MEK inhibitor and CDK4/6 inhibitor treatment. While very early in their development, Binimetinib and LEE011 has already produced objective clinical responses in about 1/3 of NRAS mutant melanoma patients with another 1/3 demonstrating clinical responses not meeting RECIST 1.1 criteria. Most impressive is the rapid nature of these responses and in some cases accompanying relief from tumor-related symptoms. Early on some significant toxicities have been observed and alternate schedules are being explored. These regimens are also being evaluated in the non-NRAS mutant, non BRAF V600 mutant melanomas. As premature as these results are they still provide excitement that targeting mutations other than BRAFV600 is feasible and may provide hope for additional therapeutic options for the majority of melanoma patients.

Trametinib for the treatment of melanoma

Advanced melanoma traditionally has had poor prognosis with limited, modestly effective and relatively toxic systemic treatment options like cytotoxic chemotherapy (dacarbazine) and immunomodulating agents (high-dose interleukin-2 and ipilimumab) which have response rates of 6-20%. With the identification of BRAF mutations found to be present in 50% of melanomas and the clinical success of serine/threonine-protein kinase B-raf inhibitors the prognostic landscape of melanoma has changed considerably. Vemurafenib and dabrafenib have been at the forefront of antimelanoma-targeted agents with a tolerable side effect profile and efficacy that compared well with the standard chemotherapy. These characteristics have led to the regulatory approval of both agents for the treatment of melanoma. However, these agents are not curative and have a short life span primarily due to rapidly occurring drug resistance. More recently, mitogen-activated protein kinase kinase (MEK) inhibitors have been found to have strong anticancer activity independently as well as when combined with other agents like B-raf inhibitors due to their activity downstream of RAF. Preclinical data and limited clinical data suggest that MEK inhibitors may be a component of effective therapy for a broad spectrum of cancers with other oncogenic drivers.

New treatment approaches in melanoma: current research and clinical prospects.

Ipilimumab and vemurafenib have changed the clinical landscape in melanoma. Both drugs offer effective treatment for metastatic melanoma, but with limitations. Ipilimumab benefits only a minority of those treated, with no means to identify them prospectively. The efficacy of vemurafenib is tied to the presence of an activating mutation in BRAF, and so is more predictable. However, acquired resistance develops within months. As we understand these, and similar, agents better, the means to select patients for treatment, to increase the duration of response and to identify the best stage at which to intervene will lead to improved outcomes for patients. Several trials are already under way or being developed to build upon these exciting discoveries.

11IN - Towards Deciphering the Genetic Landscape in Melanoma

ABSTRACT Melanoma is the deadliest form of human skin cancer, accounting for 70% of skin-cancer related deaths although it comprises only 4% of skin cancer cases. As opposed to the steady decrease in overall rate of other cancers, the incidence of melanoma continues to rise worldwide. The median patient survival is six months following diagnosis. There is a clear need to develop improved therapy for this disease. Melanoma develops through acquired mutations in cancer genes. Cancer genome sequencing can identify recurring genetic alterations that will generate new approaches to the treatment of melanoma, enabling a more personalized approach, based on gene mutation profiles of each patient's tumor. To systematically survey mutations in melanoma, we performed whole-exome sequencing of 14 matched normal and metastatic tumor DNAs. This allowed us to discover GRIN2A, a member of the ionotropic glutamate receptor family (iGluR), to be a significantly mutated gene that had not previously been identified as playing a role in melanoma. The comprehensive nature of the acquired data in this study allowed the identification of the glutamate signaling pathway to be significantly mutated, which includes GRIN2A, GRM3 and ERBB4, found to be mutated at 25, 16 and 19 percent of melanomas, respectively GRIN2A and GRM3, a metabotropic glutamate receptor (mGluR) are regulated by glutamate. GRIN2A, which is a ligand-gated ion channel, allows cations such as calcium to pass through the plasma membrane of the cell after the binding of glutamate to the receptor. GRM3 activates pathways such as the MEK pathway upon glutamate binding. The functional interplay between GRIN2A, GRM3 and ERBB4 in melanoma will be discussed and preliminary data presented. Our findings have potential therapeutic implications, as glutamate pathway modification has previously been shown to limit tumor growth. Further investigation of the glutamate pathway in melanoma a development of glutamate pathway inhibitors is therefore warranted. Disclosure All authors have declared no conflicts of interest.

Abstract 5056: A glimpse into the somatic mutation landscape of melanoma through exome sequencing of 121 tumor-normal pairs

Abstract Melanoma is an aggressive skin cancer of melanocytic origin characterized by high metastatic potential and mutation rate. Affording a survey of the wide breadth of genomic lesions found in melanoma, we present here an analysis of the somatic mutations discovered in the sequenced exomes of 121 melanoma tumor-normal pairs. We identify frequent genomic alterations both in genes previously implicated in melanoma (BRAF, NRAS, TP53, CDKN2A, PTEN) as well as in several genes whose role in melanoma tumorigenesis has not yet been established and thus are of particular interest. To do so we implement a novel method to increase the identification of genes that are significantly recurrently mutated in melanoma in the setting of its exceptionally high mutation rate. A preponderance of C>T transitions (∼85%) in the observed mutational profile reflects a history of DNA damage due to UV radiation, though the majority of somatic mutations in known melanoma genes are not C>T events. Our study broadens understanding of the genomic lesions involved in melanoma tumorigenesis, and we expect our analysis approach to inform future genomic studies of cancer lineages with similarly high mutation rates. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5056. doi:1538-7445.AM2012-5056

Next generation therapies change the landscape in melanoma

Melanoma is among the leading causes of years of life lost due to cancer. Current chemotherapy and cytokine-based immunotherapy approaches benefit only a small percentage of patients with advanced disease. However, the recent discovery of mutations in the gene encoding the serine-threonine kinase B-RAF (BRAF) raises the possibility that oncogene-targeted therapy may provide a new point of vulnerability. In parallel, a deeper understanding of the molecular mechanisms underlying antitumor T-cell activation and tolerance has provided a basis for developing therapies targeted against these processes. Results from an early phase trial with a BRAF inhibitor and a phase III trial with a novel agent that activates T cells have radically altered the prospects for improving outcomes for patients with this historically treatment-refractory disease.