BRAFV600-mutant Melanoma Patients Research Articles

Real-world use and outcomes of targeted therapy and immunotherapy for adjuvant treatment of BRAF -mutated melanoma patients in the United States.

Using a customized, harmonized US electronic health record database, real-world prescription patterns of first-line adjuvant immunotherapy and targeted therapy were retrospectively assessed for BRAF V600-mutated melanoma. Adults with BRAF V600 mutation-positive stage IIIA-D cutaneous melanoma who received first-line adjuvant immunotherapy (nivolumab or pembrolizumab) or targeted therapy (dabrafenib plus trametinib) between 1 January 2014 and 30 August 2020 in the NOBLE database were included. Patients were followed from first-line adjuvant therapy initiation for at least 6 months, until death, progression, follow-up loss, or data cutoff. Primary endpoints were proportion of patients receiving either therapy in first-line and second-line, treatment switching, treatment timing, and status at the end of first-line therapy. Secondary endpoints included discontinuation rates, recurrence-free survival (RFS), and overall survival (OS). Of 318 patients evaluated, 67.6% received nivolumab, 14.2% pembrolizumab, and 18.2% targeted therapy as first-line adjuvant therapy. Median treatment duration was longest for nivolumab (292 days) and shortest for targeted therapy (115 days). Reason for discontinuation was recorded for 195 of 274 patients who discontinued first-line therapy; most common reasons were treatment completion and treatment-related toxicity [87/158 (55.0%) and 29/158 (18.4%), respectively, in immunotherapy-treated patients; 9/37 (24.3%) and 21/37 (56.8%) in targeted therapy-treated patients]. Median RFS and OS for targeted therapy and nivolumab were not reached and were 34.6 and 38.1 months, respectively, for pembrolizumab. These results inform on prescription preferences and clinical outcomes for BRAF V600-mutated melanoma patients in the first-line adjuvant setting.

USP18 enhances the resistance of BRAF-mutated melanoma cells to vemurafenib by stabilizing cGAS expression to induce cell autophagy

This study aims to discern the possible molecular mechanism of the effect of ubiquitin-specific peptidase 18 (USP18) on the resistance to BRAF inhibitor vemurafenib in BRAF V600E mutant melanoma by regulating cyclic GMP-AMP synthase (cGAS). The cancer tissues of BRAF V600E mutant melanoma patients before and after vemurafenib treatment were collected, in which the protein expression of USP18 and cGAS was determined. A BRAF V600E mutant human melanoma cell line (A2058R) resistant to vemurafenib was constructed with its viability, apoptosis, and autophagy detected following overexpression and depletion assays of USP18 and cGAS. Xenografted tumors were transplanted into nude mice for in vivo validation. Bioinformatics analysis showed that the expression of cGAS was positively correlated with USP18 in melanoma, and USP18 was highly expressed in melanoma. The expression of cGAS and USP18 was up-regulated in cancer tissues of vemurafenib-resistant patients with BRAF V600E mutant melanoma. Knockdown of cGAS inhibited the resistance to vemurafenib in A2058R cells and the protective autophagy induced by vemurafenib in vitro. USP18 could deubiquitinate cGAS to promote its protein stability. In vivo experimentations confirmed that USP18 promoted vemurafenib-induced protective autophagy by stabilizing cGAS protein, which promoted resistance to vemurafenib in BRAF V600E mutant melanoma cells. Collectively, USP18 stabilizes cGAS protein expression through deubiquitination and induces autophagy of melanoma cells, thereby promoting the resistance to vemurafenib in BRAF V600E mutant melanoma.

An open label, non-randomised, phase IIIb study of trametinib in combination with dabrafenib in patients with unresectable (stage III) or distant metastatic (stage IV) BRAF V600-mutant melanoma: A subgroup analysis of patients with brain metastases

BackgroundDespite the poor prognosis associated with melanoma brain metastases (BM), data concerning these patients and their inclusion in clinical trials remains scarce. We report here the efficacy results of a subgroup analysis in patients with BRAFV600-mutant melanoma and BM treated with BRAF and MEK inhibitors dabrafenib (D) and trametinib (T). Patients and methodsThis phase IIIb single-arm, open-label, multicenter, French study included patients with unresectable stage IIIc or IV BRAFV600-mutant melanoma with or without BM. The present analysis focuses on patients with BM. Response rates were determined clinically and/or radiologically as per standard clinical practice. Progression-free survival (PFS) was estimated using the Kaplan Meier analysis and modelled with multivariate Cox regression model. Risk subgroups were identified using an exponential regression tree analysis. Significance was set at p < 0.05. ResultsBetween March 2015 and November 2016, 856 patients were included and 275 (32%) patients had BM. Median PFS was 5.68 months (95% confidence interval [CI], 5.29–6.87). Significant independent factors associated with shorter PFS were ECOG ≥1, elevated serum lactate dehydrogenase (LDH), ≥3 metastatic sites, and non-naïve status. The binary-split classification and regression tree modelling identified baseline LDH and ECOG status as major prognostic factors. ConclusionThis is to date the largest, close to real-world, study in advanced BRAFV600-mutant melanoma patients with BM treated with D+T. ECOG >1, ≥3 metastatic sites and elevated LDH were associated with shorter PFS, a finding previously demonstrated only in patients without BM. Further studies are warranted to determine the optimal treatment sequence in this population.

IMPemBra, a phase 2 study comparing pembrolizumab with intermittent/short‐term dual MAPK pathway inhibition plus pembrolizumab in patients with melanoma harboring the BRAFV600 mutation: Three-year survival data and translational analyses.

9552 Background: Continuous combination of MAPK pathway inhibition (MAPKi) and anti-PD-(L)1 showed high response rates, but also high frequency of treatment-related adverse events (TRAE) in BRAFV600-mutated melanoma patients (pts). Short‐time MAPKi already induces T cell infiltration in pts and was synergistic with anti-PD‐1 in a pre-clinical model. This phase 2b trial aimed to identify the optimal duration of MAPKi with dabrafenib + trametinib (D+T) in combination with pembrolizumab (PEM). We have previously shown that no SUSARs were observed, toxicity was related to duration of D+T, and response rates increased after addition of D+T. Here we present 3-year PFS and OS data and results of translational analyses. Methods: In IMPemBra, pts with treatment-naïve BRAFV600E/K mutant advanced melanoma started with PEM 200mg Q3W. After 2 cycles, pts were randomized to continue PEM only (cohort 1) or to receive in addition intermittent dabrafenib 150 mg BID + trametinib 2mg QD for 2 x 1 week (cohort 2), 2 x 2 weeks (cohort 3) or continuous for 6 weeks (cohort 4). All cohorts continued PEM for up to 2 years. Primary endpoints were safety, treatment adherence and immune-activating capacity of the different regimens. Secondary endpoints were objective response rate (ORR) and PFS, OS was an exploratory endpoint. For survival analyses, pts that received D+T (cohort 2-4) were pooled. Results: Thirty-two pts were randomized, 56% were male, 53% had M1c disease and 88% had a LDH level &lt; ULN. No new grade 3-4 TRAE were observed; frequencies were 12%, 12%, 50% and 62% for pts in cohort 1, 2, 3 and 4, respectively. ORRs were 75% in cohort 1 and 2, and 88% in cohort 3 and 4. The frequency of PD1+CD8+ T cells in peripheral blood decreased slightly during treatment and there were no differences between cohorts. In cohort 1 and 2, an increase in IFNγ signature in tumor biopsies was already observed after 6 weeks of PEM, in cohort 3-4 an increase in IFNγ signature was observed in week 9, after addition of D+T. The same pattern was observed for CD8+ T cell infiltration and PD-L1 expression. After a median follow-up of 43.5 months, the median PFS of pts treated with PEM monotherapy was 10.6 months versus 32.3 months for pts treated with PEM plus D+T (p = 0.19). The 3-year PFS rates were 25.0% and 50.0% respectively. Median OS was 40.5 months in the PEM pts and not reached for pts treated with PEM plus D+T (p = 0.32); 3-year OS rates were 62.5% and 70.8% respectively. Conclusions: IMPemBra demonstrated that short-term addition of intermittent D+T to PEM seems a more feasible, tolerable and an effective alternative for the continuous triple combination. In addition, it gives the opportunity to treat with second line targeted therapy after disease progression. Therefore, this regimen should be considered for further investigation in a larger cohort. Clinical trial information: NCT02625337.

Efficacy, safety and factors associated with disease progression in patients with unresectable (stage III) or distant metastatic (stage IV) BRAF V600-mutant melanoma: An open label, non-randomized, phase IIIb study of trametinib in combination with dabrafenib

BackgroundBRAF and MEK inhibitors combination, including dabrafenib (D) and trametinib (T) have transformed the treatment of BRAF V600-mutant advanced melanoma patients, including patients with brain metastasis (BM). In a large phase IIIb, single-arm, open-label, multicenter French study, we assessed safety, response to treatment, progression-free survival (PFS) and factors associated with progression, and stratified the population into risk groups. MethodsPatients with unresectable, advanced, BRAF V600-mutant melanoma were included, including those with the presence of BM, Eastern Cooperative Oncology Group Performance Status (ECOG PS) ≤2, elevated lactate dehydrogenase (LDH) or previous melanoma treatments. Responses were determined locally, without central review. PFS was estimated using the Kaplan–Meier analysis and modelled with multivariate Cox model. Risk subgroups were identified using a regression tree analysis. ResultsBetween March 2015 and November 2016, 856 patients received at least one D + T dose. Overall, 92% had stage IV melanoma, 38% ECOG PS ≥1, 32% BM and 37.5% elevated LDH. Median PFS was 8.02 months (95% confidence interval [CI] 7.33–8.77). Significant factors associated with lower PFS were ECOG PS ≥1, elevated LDH, ≥3 metastatic sites and presence of BM. Patients with <3 metastatic sites, ECOG = 0 and no BM had the highest probability of PFS at 6 months (83%, 95% CI 76–87) and 12 months (56%, 95% CI 47–64), respectively. ConclusionsThis is the largest prospective study in advanced BRAF V600-mutant melanoma patients treated with D + T, conducted in conditions close to ‘real-world practice’. We confirm previous findings that LDH, ECOG PS and ≥3 metastatic sites are associated with shorter PFS, but the real-world setting introduces BM as a major prognostic factor.

Inhibition of the Myocardin-Related Transcription Factor Pathway Increases Efficacy of Trametinib in NRAS-Mutant Melanoma Cell Lines.

Simple SummaryMalignant melanoma is the most aggressive skin cancer, and treatment is often ineffective due to the development of resistance to targeted therapeutic agents. The most prevalent form of melanoma with a mutated BRAF gene has an effective treatment, but the second most common mutation in melanoma (NRAS) leads to tumors that lack targeted therapies. In this study, we show that NRAS mutant human melanoma cells that are most resistant to inhibition of the oncogenic pathway have a second activated pathway (Rho). Inhibiting that pathway at one of several points can produce more effective cell killing than inhibition of the NRAS pathway alone. This raises the possibility that such a combination treatment could prove effective in those melanomas that fail to respond to existing targeted therapies such as vemurafenib and trametinib.The Ras/MEK/ERK pathway has been the primary focus of targeted therapies in melanoma; it is aberrantly activated in almost 80% of human cutaneous melanomas (≈50% BRAFV600 mutations and ≈30% NRAS mutations). While drugs targeting the MAPK pathway have yielded success in BRAFV600 mutant melanoma patients, such therapies have been ineffective in patients with NRAS mutant melanomas in part due to their cytostatic effects and primary resistance. Here, we demonstrate that increased Rho/MRTF-pathway activation correlates with high intrinsic resistance to the MEK inhibitor, trametinib, in a panel of NRAS mutant melanoma cell lines. A combination of trametinib with the Rho/MRTF-pathway inhibitor, CCG-222740, synergistically reduced cell viability in NRAS mutant melanoma cell lines in vitro. Furthermore, the combination of CCG-222740 with trametinib induced apoptosis and reduced clonogenicity in SK-Mel-147 cells, which are highly resistant to trametinib. These findings suggest a role of the Rho/MRTF-pathway in intrinsic trametinib resistance in a subset of NRAS mutant melanoma cell lines and highlight the therapeutic potential of concurrently targeting the Rho/MRTF-pathway and MEK in NRAS mutant melanomas.

Dosing of BRAF and MEK Inhibitors in Melanoma: No Point in Taking a Break

Resistance to BRAF/MEK inhibitor treatment occurs in most patients with advanced BRAFV600-mutant melanoma. Intermittent drug dosing had been proposed as a strategy to circumvent resistance. In a clinical trial published in Nature Medicine, continuous dosing of BRAF/MEK inhibitors produced superior progression-free survival compared to intermittent dosing in BRAFV600-mutant melanoma patients.

1114P A real-world study of vemurafenib plus anti-PD-1 antibody in Chinese patients with advanced BRAF V600-mutant melanoma

Preclinical data suggest that BRAF inhibition provides a more favorable immune microenvironment for subsequent response to immunotherapy. We aimed to evaluate the efficacy and safety of combining vemurafenib (BRAF inhibitor) with a programmed death 1 (PD-1) inhibitor in patients with BRAFV600-mutant melanoma in China. Advanced BRAFV600-mutant melanoma patients treated with vemurafenib and anti-PD-1 antibody at Sun-Yat Sen University Cancer Center between June 2017 and May 2019 were retrospectively analyzed. Vemurafenib was administered with a 4–6-weeks run-in period followed by PD-1 blockade (pembrolizumab or toripalimab) combined with vemurafenib until disease progression or unacceptable toxicity. Response was assessed by the Response Evaluation Criteria in Solid Tumors version 1.1. In total, 39 patients were included. All the patients had tumor shrinkage. The objective response rate was 64.1% (95% CI, 48.7–79.4) and the complete response was observed in 8 (20.5%; 95% CI, 7.7–33.3) patients. The median progression-free survival (PFS) was 13.2 months (95% CI: 8.2–18.2). The median duration of response (DOR), and overall survival (OS) were not reached after a median follow-up of 12.1 months. The response was ongoing in 16 (41%) patients. The estimated 1-year survival rate was 86.7%. During the combination therapy, treatment-related adverse events (TRAEs) of any grade occurred in 36 (92.3%) patients. Eleven patients (28.2%) experienced grade 3/4 TRAEs, 10 presented with rash and 1 with elevated transaminase. TRAEs led to discontinuation of ≥1 study drug in seven (17.9%) patients. Programmed death ligand 1 expression on the tumor cell and tumor mutation burden at baseline did not correlate with response rate and survival time.Table: 1114PCharacteristicNo. of patients (%), n=39Age, years51 (24–77)Male26 (66.7)ECOG022 (56.7)117 (43.6)Clinical subtype of primary tumorAcral2 (5.1)CSD11 (28.2)Non-CSD19 (48.7)Unknown7 (17.9)Brain metastasesYes6 (15.4)No33 (84.6)Liver metastasesYes11 (28.2)No28 (71.8)Metastatic organs>217 (43.6)≤222 (56.4)LDH≤UNL30 (76.9)＞UNL9 (23.1)Prior systemic therapyNo29 (74.4)Yes10 (25.6) Open table in a new tab Vemurafenib combined with anti-PD-1 antibody had promising clinical activity and manageable safety. Toxicity, especially rash, is more common for this combination than for either agent alone.

The IMPemBra trial, a phase II study comparing pembrolizumab with intermittent/short‐term dual MAPK pathway inhibition plus pembrolizumab in melanoma patients harboring the BRAFV600 mutation.

10021 Background: Continuous combination of MAPK inhibition (MAPKi) and anti-PD-(L)1 has been investigated by several trials to improve outcome of BRAFV600 mutated melanoma patients. A major obstacle for continuous combination is the high frequency (~60%) of grade 3-4 treatment-related adverse events (TRAE) for which many patients need to discontinue (~40%). In a preclinical model we showed that short‐time MAPKi induces T cell infiltration and is synergistic with anti-PD‐1. In patients T cell infiltration increased after short-term MAPKi, while after &gt; 2 weeks this was often diminished. The aim of this phase 2b study was to identify the optimal duration of MAPKi with dabrafenib (BRAFi) + trametinib (MEKi) in combination with pembrolizumab (anti-PD-1) in terms of safety, feasibility and immune-activating capacity. Methods: Treatment-naïve BRAFV600E/K mutant advanced melanoma patients started pembrolizumab (PEM) 200mg Q3W and were randomized in week 6 to continue PEM only (cohort 1) or to receive in addition intermittent dabrafenib (D) 150 mg BID + trametinib (T) 2mg QD for 2 x 1 week (cohort 2), 2 x 2 weeks (cohort 3), or continuous for 6 weeks (cohort 4). All cohorts continued PEM for up to 2 years. Primary endpoints were safety and treatment-adherence. Secondary endpoints were objective response rate (ORR, RECIST 1.1) at week 6, 12, 18 compared to baseline and PFS. Results: Between June 2016 and August 2018, 32 patients have been included; 56% were male, 50% had M1c disease and the majority had a BRAFV600E mutation (81%) and a baseline LDH level &gt; ULN (87%). Grade 3-4 TRAE were observed in 12%, 12%, 50%, and 62% of patients in cohort 1, 2, 3, and 4, respectively. All planned D+T was given in 88%, 63%, and 38% of patients in cohort 2, 3, and 4. Most patients needed to interrupt or discontinue D+T due to fever or elevated liver enzymes. ORR at week 6, week 12, and week 18 were 38%, 62%, and 62% in cohort 1, 25%, 62%, and 75% in cohort 2, 25%, 50%, and 75% in cohort 3 and 0%, 62%, and 50% in cohort 4. After a median follow-up of 17.4 months, the median PFS of patients treated with PEM monotherapy was 10.6 months compared to 27.0 months for patients treated with PEM and short-term/intermittent D+T (p = 0.13). Conclusions: Combination of PEM plus intermittent D+T seems more feasible and tolerable than continuous triple therapy. Intermittent short-time combination therapy might be equally effective, enables therapy with MAPKi as a second line, and therefore warrants further investigation in a larger patient cohort. Clinical trial information: NCT02625337.

BRAFi induced demethylation of miR-152-5p regulates phenotype switching by targeting TXNIP in cutaneous melanoma.

Treatment of advanced BRAFV600-mutant melanoma using BRAF inhibitors (BRAFi) eventually leads to drug resistance and selects for highly metastatic tumor cells. We compared the most differentially dysregulated miRNA expression profiles of vemurafenib-resistant and highly-metastatic melanoma cell lines obtained from GEO DataSets. We discovered miR-152-5p was a potential regulator mediating melanoma drug resistance and metastasis. Functionally, knockdown of miR-152-5p significantly compromised the metastatic ability of BRAFi-resistant melanoma cells and overexpression of miR-152-5p promoted the formation of slow-cycling phenotype. Furthermore, we explored the cause of how and why miR-152-5p affected metastasis in depth. Mechanistically, miR-152-5p targeted TXNIP which affected metastasis and BRAFi altered the methylation status of MIR152 promoter. Our study highlights the crucial role of miR-152-5p on melanoma metastasis after BRAFi treatment and holds significant implying that discontinuous dosing strategy may improve the benefit of advanced BRAFV600-mutant melanoma patients.

Optimal treatment strategy for metastatic melanoma patients harboring BRAF-V600 mutations.

BRAF-V600 mutations occur in approximately 50% of patients with metastatic melanoma. Immune-checkpoint inhibitors and targeted therapies are both active as first-line treatments in these patients regardless of their mechanisms of action and toxicities. However, an upfront therapeutic strategy is still controversial. In fact, waiting for results of ongoing clinical trials and for new biomarkers, clinicians should base their decision on the clinical characteristics of the patient and on the biological aspects of the tumor. This review provides an overview on BRAF-V600 mutations in melanoma and will discuss their prognostic and clinical significance. Moreover, it will suggest a therapeutic algorithm that can drive therapeutic choice in a first-line setting for BRAF-V600 mutant melanoma patients.

Switch to checkpoint inhibition after targeted therapy at time of progression or during ongoing response: A retrospective single-centre experience in patients with BRAF-mutated melanoma.

BRAF+MEK inhibition is preferentially applied as first-line therapy in BRAF V600-mutated melanoma patients with unfavourable prognostic features, due to the ability of targeted therapy (TT) to induce rapid symptom control, decrease tumour burden and normalize lactate dehydrogenase (LDH) levels. In addition, short-term TT transiently increases tumour antigen presentation and tumour influx of T cells. Therefore, it might be favourable to switch TT to checkpoint inhibition (CPI) before progression (PD). We retrospectively analysed melanoma patients treated first line with TT (TT1) and who subsequently switched to CPI during response to TT (sDR group) or at progression upon TT (sPD group). We identified 74 patients (n=37 sDR group and n=37 sPD group). ORR to CPI was 27.0% in the sDR group versus 24.3% in the sPD group (p=.790). Median was PFS 2.5months versus 1.2months (p=.145), and median OS was 30.6 versus 14.1months (p=.007). After adjusting for baseline differences and known prognostic factors, hazard ratios (HRs) favouring sDR were 0.89 for PFS upon CPI (p=.956) and 0.48 for OS (p=.055). Thus, patients switching to CPI during ongoing clinical benefit from TT do not have an inferior outcome. Due to baseline imbalances and small patient population, a favourable trend for the sDR group can be hypothesized only.

1338P - Factors associated with disease progression in patients treated with trametinib in combination with dabrafenib for unresectable advanced BRAFV600-mutant melanoma: An open label, non randomized study

BackgroundBRAF and MEK inhibitors dabrafenib (D) and trametinib (T) have transformed BRAFV600-mutant melanoma patients’ (pts) treatment. In a large prospective trial of pts treated with combination D+T, which also included pts with brain metastasis (BM), we assessed factors associated with progression and stratified the population into risk groups using regression tree analysis (RTA). MethodsThis phase IIIb single arm, open label, multicenter, French study included in 40 centers pts with histologically confirmed unresectable stage IIIc or IV BRAFV600-mutant melanoma. Selection criteria allowed presence of BM, ECOG ≤2, previous advanced melanoma treatments (except BRAFi+MEKi combination). Progression-free survival (PFS) was estimated using the Kaplan Meier analysis and modeled with multivariate Cox regression model. Risk subgroups were identified using an exponential RTA. Significance was set at p<0.05. ResultsBetween March 2015 and November 2016, 914 pts were screened and 856 received at least 1 dose of D+T. Overall, 92% of pts had AJCC stage IV melanoma, 38% ECOG ≥1 and 32% BM. Among the 587 pts with known LDH at baseline, 38% had >ULN. Median PFS was 8.02 months (95%CI, 7.33-8.77). Significant independent factors associated with lower PFS were ECOG ≥1, elevated serum LDH, ≥3 metastatic sites, and presence of BM (Table). Pts with <3 metastatic sites, ECOG 0 and absence of BM had the highest probability of PFS at 6 (83% [95% CI, 76-87]) and 12 months (56% [95% CI, 47-64]). No unexpected AE were reported.Table1338P Multivariate Cox proportional hazards analysis of PFS by prognostic factors - All Subjects Treated Population (N=856)TableN (%)HR95% CIp valueLDH at baseline*<1 ULN366 (42.8)1 (=reference)--[1 - 2[ ULN160 (18.7)1.64[1.26 - 2.14]0.0003≥2 ULN61 (7.1)2.45[1.70 - 3.53]<.0001Missing269 (31.4)1.34[1.05 - 1.71]0.0167ECOG*0531 (62.0)1 (=reference)--1242 (28.3)1.49[1.19 - 1.87]0.0005≥283 (9.7)2.32[1.69 - 3.19]<.0001Metastatic sites*<3344 (40.2)1 (=reference)--≥3445 (52.0)1.61[1.28 - 2.02]<.0001Missing67 (7.8)1.05[0.63 - 1.74]0.8494Presence of brain metastasis*No579 (67.6)1 (=reference)--Yes275 (32.1)1.38[1.11 - 1.71]0.0043Missing2 (0.23)---*Factors included in the RTA. ConclusionsThis is to date the largest prospective study in advanced BRAFV600-mutant melanoma pts treated with D+T. The study was carried out in conditions close to the real-world. We confirm findings of registration trials that LDH, ECOG and ≥3 metastatic sites are associated with shorter PFS, but the real-world setting introduces BM as a major prognostic factor. Editorial acknowledgementJone Iriondo-Alberdi (PhD) from ITEC Services. Legal entity responsible for the studyNovartis Pharma S.A.S. (France). FundingNovartis Pharma S.A.S. (France). DisclosureP. Saiag: Travel / Accommodation / Expenses: Amgen; Travel / Accommodation / Expenses, Non-remunerated activity/ies: Bristol-Myers Squibb; Travel / Accommodation / Expenses, Non-remunerated activity/ies: Merck Sharp & Dohme ; Travel / Accommodation / Expenses: Merck Serono; Travel / Accommodation / Expenses: Pfizer; Research grant / Funding (self), Travel / Accommodation / Expenses, Non-remunerated activity/ies: Roche-Genentech; Travel / Accommodation / Expenses: Pierre Fabre; Travel / Accommodation / Expenses, Non-remunerated activity/ies: Novartis. C. Robert: Advisory / Consultancy: Roche; Advisory / Consultancy: Bristol-Myers Squibb; Advisory / Consultancy: Merck Sharp & Dohme ; Advisory / Consultancy: Sanofi; Advisory / Consultancy: Novartis; Advisory / Consultancy: Amgen; Advisory / Consultancy, Participation to Boards and Steering Committees: Pierre Fabre. J.J. Grob: Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Bristol-Myers Squibb; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Merck Sharp & Dohme ; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Roche; Honoraria (self), Advisory / Consultancy: Novartis; Honoraria (self), Advisory / Consultancy: Amgen; Honoraria (self), Advisory / Consultancy: Merck; Honoraria (self), Advisory / Consultancy: Pierre Fabre; Honoraria (self), Advisory / Consultancy: Pfizer; Honoraria (self), Advisory / Consultancy: Incyte. L. Mortier: Honoraria (self), Advisory / Consultancy: Amgen; Honoraria (self), Advisory / Consultancy: BMS; Honoraria (self), Advisory / Consultancy: Roche; Honoraria (self), Advisory / Consultancy: GSK/Novartis; Honoraria (self), Advisory / Consultancy: MSD; Honoraria (self), Advisory / Consultancy: Leo; Honoraria (self): Merck Serono; Honoraria (self): Sanofi; Honoraria (self): Pierre Fabre; Honoraria (self): Novartis. C. Lebbe: Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Bristol-Myers Squibb; Honoraria (self), Travel / Accommodation / Expenses: Merck Sharp & Dohme ; Honoraria (self): Roche; Honoraria (self): Novartis; Honoraria (self): Amgen; Honoraria (self): Merck; Honoraria (self): Pierre Fabre; Honoraria (self): Pfizer; Honoraria (self): Incyte. S. Mansard: Advisory / Consultancy: Novartis. F. Grange: Advisory / Consultancy: Novartis. E. Neidhardt: Travel / Accommodation / Expenses: BMS. T. Lesimple: Advisory / Consultancy: Novartis; Advisory / Consultancy: MSD; Advisory / Consultancy: Incyte; Advisory / Consultancy: Pierre Fabre; Research grant / Funding (self): Roche. C. Bedane: Advisory / Consultancy: Novartis. S. Dalac-Rat: Advisory / Consultancy: Novartis; Advisory / Consultancy: Roche; Advisory / Consultancy: BMS; Advisory / Consultancy: Pierre Fabre. C. Nardin: Advisory / Consultancy: Novartis; Advisory / Consultancy: BMS; Advisory / Consultancy: MSD. A. Szenik: Full / Part-time employment: Novartis. A. Denden: Full / Part-time employment: Novartis. C. Dutriaux: Honoraria (self), Advisory / Consultancy: Novartis. All other authors have declared no conflicts of interest.

Dabrafenib and Trametinib\xa0prolong coagulation through the inhibition of tissue factor in BRAFv600e mutated melanoma cells in vitro

BackgroundNeoplastic cells promote a hypercoagulable state by the expression of cell surface proteins, such as tissue factor. In BRAFv600 mutated melanoma patients upon BRAF inhibitors, a hypercoagulable state correlates with prognosis, while a down-regulation of the hemostatic parameters is observed in patients responders as compared to non responders. The present study was intended to better clarify the strict relationship between coagulation mediators and target therapy in melanoma.MethodsThe expression of tissue factor was investigated after the treatment with the BRAF inhibitor Dabrafenib and the MEK inhibitor Trametinib in the BRAFv600e mutated melanoma cell lines A-375 and SK-MEL-28, together with its ability to activate the coagulation cascade.ResultsDabrafenib and Trametinib caused the down-regulation of TF in both cell lines A-375 and SK-MEL-28. For the cell line A-375 the effect was evident both at RNA and procoagulant activity; for the cell line SK-MEL-28 only at RNA level without any variation of the protein. Interestingly, when in contact with plasma deficient of factor VII, both cell lines were not able to activate the coagulation cascade.ConclusionsThe present study provides the first in vitro observation that tissue factor expressed in melanoma cells may contribute to the modulation of the coagulation state of patients in the treatment with BRAF inhibitors.

Panniculitis and vitiligo occurring during BRAF and MEK inhibitors combination in advanced melanoma patients: Potential predictive role of treatment efficacy.

Panniculitis and vitiligo-like lesions have been recently identified as rare cutaneous side effects of the combination of BRAF and MEK inhibitors, a standard of care in metastatic and locally advanced BRAF V600 mutated melanoma. An immune-mediated mechanism has been advocated in the pathogenesis of these skin lesions. Herein we retrospectively reviewed our institutional experience with the aim to explore the association between the occurrence of panniculitis and vitiligo-like lesions during combination therapy with dabrafenib (D) and trametinib (T) and outcome of advanced melanoma patients. Among 52 consecutive BRAF V600 mutated melanoma patients submitted to DT in our center, 12 (23%) developed immune related skin lesions (IRSLs): 8 panniculitis and 4 vitiligo. Patients with IRSLs diagnosis obtained a better disease response (83% versus 25%) (p = 0.001) than their counterpart and had a longer progression free survival and overall survival. The association of IRSLs and lower risk of disease progression (HR 0.19; CI 95% 0.04–0.90; p = 0.043) was confirmed after adjusting for major prognostic factors in multivariate analysis. IRSLs might represent an easy predictive surrogate marker for treatment response and favourable outcome in melanoma patients submitted to DT combination therapy.

SIRT6 haploinsufficiency induces BRAFV600E melanoma cell resistance to MAPK inhibitors via IGF signalling

While multiple mechanisms of BRAFV600-mutant melanoma resistance to targeted MAPK signaling inhibitors (MAPKi) have been reported, the epigenetic regulation of this process remains undetermined. Here, using a CRISPR–Cas9 screen targeting chromatin regulators, we discover that haploinsufficiency of the histone deacetylase SIRT6 allows melanoma cell persistence in the presence of MAPKi. Haploinsufficiency, but not complete loss of SIRT6 promotes IGFBP2 expression via increased chromatin accessibility, H3K56 acetylation at the IGFBP2 locus, and consequent activation of the IGF-1 receptor (IGF-1R) and downstream AKT signaling. Combining a clinically applicable IGF-1Ri with BRAFi overcomes resistance of SIRT6 haploinsufficient melanoma cells in vitro and in vivo. Using matched melanoma samples derived from patients receiving dabrafenib + trametinib, we identify IGFBP2 as a potential biomarker for MAPKi resistance. Our study has not only identified an epigenetic mechanism of drug resistance, but also provides insights into a combinatorial therapy that may overcome resistance to standard-of-care therapy for BRAFV600-mutant melanoma patients.

1225PD - Prognostic impact of early complete metabolic response on FDG-PET, in BRAF V600 mutant metastatic melanoma patients treated with combination vemurafenib & cobimetinib

Background: Imaging with FDG-PET allows early recognition of metabolic response to targeted agents. We evaluated the timing of complete metabolic response (CMR) on PET as a predictor of clinical outcome in BRAF V600 mutant melanoma patients treated with vemurafenib and cobimetinb, as part of the BRIM-7 trial. Methods: BRAF inhibitor naïve patients from BRIM-7 were included if they had evaluable PET scans at baseline, in cycle 1 (C1) (D10-15) and in C2 (D35-49). Metabolic response was evaluated by percentage injected dose (%ID). 52 of 63 BRAF-naïve patients were eligible for analysis (3 excluded - no C1 scan; 6 no C2 scan; 2 unevaluable scans due to excessive physiological muscle uptake). The primary aim was to evaluate the prognostic significance of an early CMR to combination vemurafenib and cobimetinib therapy. We divided patients into 3 groups, based on timing of CMR attainment. Results: 13 patients achieved CMR in cycle 1 (CMR1), 15 patients achieved CMR in cycle 2 (CMR2) and 24 patients did not achieve CMR within the first 2 cycles of treatment (noCMR). The median, 2 year and 3 year progression free survival (PFS) and overall survival (OS) of the 3 above groups are summarized in Table.Table1225PDCMR1CMR2No CMRMedian PFS (yrs)Not reached1.11.02 yr PFS (%, 95% CI)83.9 (65.7-100)13.3 (3.7-48.4)37.5 (22.4-62.9)3 yr PFS (%, 95% CI)71.9 (48.8-100)13.3 (3.7-48.4)18.8 (7.9-44.5)Median OS (yrs)Not reached2.42.52 yr OS (%, 95% CI)84.6 (67.1-100)63.0 (41.5-95.8)58.3 (41.6-81.8)3 yr OS (%, 95% CI)74.0 (52.2-100)21.0 (6.3-70.2)30.9 (16.5-57.9)Patients achieving CMR1 had significantly better outcome than patients achieving CMR2 in terms of PFS (HR 0.18, 95% CI 0.05-0.62) and OS (HR 0.23, 95% CI 0.06-0.85). Similar results were observed comparing CMR1 over no CMR in PFS (HR 0.19, 95% CI 0.06-0.64) and in OS (HR 0.25, 95% CI 0.07-0.87). There was no difference between the CMR2 and noCMR groups in terms of PFS or OS. Open table in a new tab Patients achieving CMR1 had significantly better outcome than patients achieving CMR2 in terms of PFS (HR 0.18, 95% CI 0.05-0.62) and OS (HR 0.23, 95% CI 0.06-0.85). Similar results were observed comparing CMR1 over no CMR in PFS (HR 0.19, 95% CI 0.06-0.64) and in OS (HR 0.25, 95% CI 0.07-0.87). There was no difference between the CMR2 and noCMR groups in terms of PFS or OS. Conclusions: Attainment of CMR on an early D10-14 PET was highly predictive of long-term survival with BRAF and MEK inhibition. However, attainment of CMR at a later time point at D35-49 did not appear predictive of a survival benefit. In fact, no difference in PFS or OS could be observed in patients who achieved CMR at D35-49, compared to those patients who did not attain CMR. Correlative science analysis to investigate the mechanism of these observations are underway. Clinical trial identification: number: NCT01271803 Legal entity responsible for the study: Genentech Roche Funding: Genentech Roche Disclosure: J. Frederickson: Employer of Genentech and has Roche stocks D. Colburn, N. Choong, M. Wongchenko: Employee of Roche-Genentech. All other authors have declared no conflicts of interest.

1135P - COMBI-rechallenge: a phase II clinical trial on dabrafenib plus trametinib in BRAFV600-mutant melanoma patients who previously experienced progression on BRAF(+MEK)-inhibition

1135P - COMBI-rechallenge: a phase II clinical trial on dabrafenib plus trametinib in BRAFV600-mutant melanoma patients who previously experienced progression on BRAF(+MEK)-inhibition

Phase I study of vemurafenib and heat shock protein 90 (HSP90) inhibitor XL888 in metastatic BRAF V600 mutant melanoma.

9544Background: BRAF inhibitors are clinically active in advanced BRAFV600 mutant melanoma patients, but resistance is common. Multiple resistance mechanisms involve HSP90 clients and preclinical d...

Dissecting Therapeutic Resistance to ERK Inhibition.

The MAPK pathway is frequently activated in many human cancers, particularly melanomas. A single-nucleotide mutation in BRAF resulting in the substitution of glutamic acid for valine (V(600E)) causes constitutive activation of the downstream MAPK pathway. Selective BRAF and MEK inhibitor therapies have demonstrated remarkable antitumor responses in BRAF(V600) (E)-mutant melanoma patients. However, initial tumor shrinkage is transient and the vast majority of patients develop resistance. We previously reported that SCH772984, an ERK 1/2 inhibitor, effectively suppressed MAPK pathway signaling and cell proliferation in BRAF, MEK, and concurrent BRAF/MEK inhibitor-resistant tumor models. ERK inhibitors are currently being evaluated in clinical trials and, in anticipation of the likelihood of clinical resistance, we sought to prospectively model acquired resistance to SCH772984. Our data show that long-term exposure of cells to SCH772984 leads to acquired resistance, attributable to a mutation of glycine to aspartic acid (G(186D)) in the DFG motif of ERK1. Structural and biophysical studies demonstrated specific defects in SCH772984 binding to mutant ERK. Taken together, these studies describe the interaction of SCH772984 with ERK and identify a novel mechanism of ERK inhibitor resistance through mutation of a single residue within the DFG motif. Mol Cancer Ther; 15(4); 548-59. ©2016 AACR.