BRAF-mutant Melanoma Research Articles

BI26 Treatment-induced scleroderma in a patient with metastatic melanoma

Abstract We present a 71-year-old woman who presented with sclerodermoid plaques affecting the abdomen and lower limbs, following a single cycle of nivolumab and ipilimumab 20 months prior for BRAF-mutant metastatic melanoma (pulmonary and hepatic metastases). Immunotherapy was discontinued owing to iatrogenic colitis, confirmed on flexible sigmoidoscopy, and requiring oral prednisolone, infliximab and, later, modified-release beclomethasone dipropionate. Owing to the progression of hepatic disease, she was commenced on targeted therapy with dabrafenib and trametinib. A lesional punch biopsy was performed; histological analysis demonstrated a dense dermis with mild chronic inflammatory infiltrate, in keeping with a diagnosis of scleroderma. Treatment with a combination of topical corticosteroids and vitamin D analogues improved disease from 15% body surface area (BSA) to 3% after 4 months. We performed a literature search in PubMed for articles on immunotherapy-related scleroderma published up to August 2022 and identified 18 articles that met our inclusion criteria. Scleroderma was reported in patients with melanoma, non-small-cell lung cancer, renal cell carcinoma, rectal adenocarcinoma, adenocarcinoma of the lung and large-cell neuroendocrine lung cancer treated with pembrolizumab, nivolumab, atezolizumab and ipilimumab. Latency of onset ranged from 0 to 18 months, and treatment included topical and systemic corticosteroids, mycophenolate mofetil, hydroxychloroquine, cyclophosphamide, infliximab and immunoglobulins, with varying treatment outcomes. There was no clear relationship between cancer subtype, duration of treatment and response to treatment. Furthermore, the lack of documented quantitative or semiquantitative measurements for improvement such as BSA and modified Rodnan skin score is limiting. Our case report is important in promoting the awareness of localized scleroderma as a rare side-effect of immunotherapy and highlights the various treatment options available.

The Pro-Oncogenic Sphingolipid-Metabolizing Enzyme β-Galactosylceramidase Modulates the Proteomic Landscape in BRAF(V600E)-Mutated Human Melanoma Cells.

β-Galactosylceramidase (GALC) is a lysosomal enzyme involved in sphingolipid metabolism by removing β-galactosyl moieties from β-galactosylceramide and β-galactosylsphingosine. Previous observations have shown that GALC may exert pro-oncogenic functions in melanoma and Galc silencing, leading to decreased oncogenic activity in murine B16 melanoma cells. The tumor-driving BRAF(V600E) mutation is present in approximately 50% of human melanomas and represents a major therapeutic target. However, such mutation is missing in melanoma B16 cells. Thus, to assess the impact of GALC in human melanoma in a more relevant BRAF-mutated background, we investigated the effect of GALC overexpression on the proteomic landscape of A2058 and A375 human melanoma cells harboring the BRAF(V600E) mutation. The results obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS) demonstrate that significant differences exist in the protein landscape expressed under identical cell culture conditions by A2058 and A375 human melanoma cells, both harboring the same BRAF(V600E)-activating mutation. GALC overexpression resulted in a stronger impact on the proteomic profile of A375 cells when compared to A2058 cells (261 upregulated and 184 downregulated proteins versus 36 and 14 proteins for the two cell types, respectively). Among them, 25 proteins appeared to be upregulated in both A2058-upGALC and A375-upGALC cells, whereas two proteins were significantly downregulated in both GALC-overexpressing cell types. These proteins appear to be involved in melanoma biology, tumor invasion and metastatic dissemination, tumor immune escape, mitochondrial antioxidant activity, endoplasmic reticulum stress responses, autophagy, and/or apoptosis. Notably, analysis of the expression of the corresponding genes in human skin cutaneous melanoma samples (TCGA, Firehose Legacy) using the cBioPortal for Cancer Genomics platform demonstrated a positive correlation between GALC expression and the expression levels of 14 out of the 27 genes investigated, thus supporting the proteomic findings. Overall, these data indicate for the first time that the expression of the lysosomal sphingolipid-metabolizing enzyme GALC may exert a pro-oncogenic impact on the proteomic landscape in BRAF-mutated human melanoma.

Inmunoterapia vs. terapia diana en el paciente con melanoma avanzado y mutación BRAF V600, ¿por cuál comenzar?

Systemic treatment with immunotherapy or targeted therapy can significantly improve survival in patients with advanced (metastatic or high-risk) melanoma. Fifty percent of patients with melanoma have a BRAF mutation. Decisions on optimal sequencing of systemic treatments should take into account drug- and tumor-related factors and patient characteristics. Although the combination of ipilimumab and nivolumab is associated with the best survival outcomes, it is associated with significant toxicity. Targeted therapy may be a more favorable option in certain clinical situations. We review the literature on immunotherapy and targeted therapy in melanoma and present an algorithm for guiding decision-making on their use as first-line systemic treatments for advanced BRAF-mutated melanoma.

Cardiotoxicity of BRAF/MEK Inhibitors: A Longitudinal Study Incorporating Contemporary Definitions and Risk Scores

BackgroundRapidly accelerated fibrosarcoma B-type (BRAF) and mitogen-activated extracellular signal-regulated kinase (MEK) inhibitors have revolutionized treatment for patients with BRAF-mutated melanoma. Although left ventricular systolic dysfunction associated with these therapies has been reported in clinical trials, the real-world incidence is poorly defined, as are risk factors for its development. ObjectivesThis study sought to characterize the incidence, time course, and risk factors for cancer therapy–related cardiac dysfunction (CTRCD) in patients with melanoma receiving BRAF and MEK inhibitors. MethodsPatients with melanoma treated with BRAF and MEK inhibitors at a cancer hospital network between June 1, 2017, and June 30, 2020, were included retrospectively. CTRCD was defined as mild, moderate, or severe according to International Cardio-Oncology Society (ICOS) definitions. Baseline cardiotoxicity risk stratification was performed using the Heart Failure Association/ICOS tool. ResultsOf the 63 patients included, 27% developed CTRCD (17% mild and 10% moderate). No patients developed severe CTRCD or symptomatic heart failure. CTRCD occurred most frequently in patients considered to be at “low” and “medium” baseline risk of cardiotoxicity (82%). The baseline left ventricular ejection fraction and global longitudinal strain were not different in patients who developed moderate CTRCD vs those who did not. Left ventricular internal diameters in diastole and systole were larger in patients who developed moderate CTRCD compared with those who did not (left ventricular internal diameter in diastole: 4.9 ± 0.6 cm vs 4.3 ± 0.6 cm; P = 0.023; left ventricular internal diameter in systole: 3.3 ± 0.4 cm vs 2.8 ± 0.5 cm; P = 0.039). ConclusionsBRAF and MEK inhibitor–associated CTRCD is common. The utility of the Heart Failure Association/ICOS risk stratification tool appears limited in this group, and better risk prediction tools are needed. The long-term consequences of CTRCD, particularly mild CTRCD, warrant evaluation in larger prospective studies.

Повторное применение ингибиторов BRAF и MEK у пациентов с метастатической меланомой кожи с мутацией в гене BRAF

In this paper we review the existing data and our clinical experience of repeated use of combination therapy with BRAF/MEK inhibitors (BRAFi/MEKi) in the treatment of patients with BRAF-mutated metastatic melanoma of the skin. Recent advances in medical oncology significantly increased the life expectancy of patients with metastatic and/or unresectable melanoma of the skin. However, some patients develop resistance to therapy. Retreatment after interruption or "intermediate" therapy may be of clinical benefit. Contemporary drug therapy becomes more available and there are fewer challenges to chose the first and second line therapy for patients with metastatic and/or unresectable melanoma, but there are still questions on subsequent treatment options when BRAFi/MEKi therapy had been used after the disease progression following the initial objective response. In this article, we review the definitions of “retreatment” or “rechallenge”, give the overview of the literature data, and present our clinical experience

A powerful drug combination strategy targeting BRAF-mutant melanoma.

3152 Background: BRAF inhibitors, such as vemurafenib and dabrafenib, are effective in treating patients with melanoma harboring (V600E) BRAF mutations. These drugs block the activity of the mutated BRAF protein, which impacts the development and progression of melanoma. Despite initial efficacy, drug resistance reliably occurs leading to disease relapse. Here we show how BRAF inhibitors cause metabolic reprogramming in melanoma cells to achieve drug resistance and promote cell survival. Previously we demonstrated that wild-type isocitrate dehydrogenase 1 (wtIDH1) supports mitochondrial function and maintains redox homeostasis in melanoma, and that an FDA-approved mutant IDH1 inhibitor, ivosidenib (AG-120), is actually a potent wtIDH1 inhibitor. Thus, we hypothesized that wtIDH1 inhibition would synergize with BRAF inhibition. Methods: Metabolomic profiling using LC-MS determined the impact of BRAF inhibition on cellular metabolism. Cell viability was assessed by PicoGreen in drug combination assays. Synergism was calculated using the Bliss-Independence dose-response model for drug interaction. In vivo modeling of AG-120 in combination with BRAF inhibition used melanoma cell xenografts in athymic nude mice for tumor volume analyses, and survival studies were performed in both immunocompetent C57BL/6J mice (murine YUMM1.7 cells) and immunocompromised athymic nude mice (human A375 cells). Results: Metabolomics data suggest that BRAF-mutated melanoma cells treated with BRAF inhibitors increased oxidative metabolism and mitochondrial dependence (i.e., survival adaptations). These alterations suggest an opportunity for mitochondrial inhibitors to improve drug efficacy. Targeting wtIDH1 with AG-120 in combination with dabrafenib significantly reduced melanoma cell viability. A positive synergy score and Bliss score greater than 1 indicate that the combined treatment was more effective in reducing cell viability than either treatment alone. Further, the combination of AG-120 and dabrafenib was the most effective in vivo, reducing tumor growth in the BRAF-mutated melanoma xenograft model, and improving mouse survival compared to monotherapy controls. Mice tolerated combination therapy with no reduction in body weight observed. Conclusions: Our findings indicate that dual inhibition of mutated BRAF and wild-type IDH1 represents a novel treatment strategy for BRAF-mutated melanomas, with potential for application to other BRAF-mutated cancers (e.g., colon, hepatobiliary, thyroid, etc.).

A pilot study of the neoadjuvant use of vemurafenib plus cobimetinib in patients with BRAF-mutant melanoma with palpable lymph node metastases: Survival results.

9579 Background: Melanoma patients with palpable nodal metastases have a very poor prognosis with the majority recurring within the first 2-3 years post-resection with survival ranging from 20-50% at 5 years. We aimed to ascertain if patients with a BRAF V600 mutation that receive vemurafenib and cobimetinib before surgery (neoadjuvantly) have a higher probability of resectability, pathologic complete response (pCR), and a lower risk of local recurrence and a longer disease free survival (DFS), distant metastatic free survival (DMFS) and overall survival (OS). Methods: This was a single arm, prospective, multi centre phase II study in patients with histologically confirmed, BRAF V600 mutated Stage IIIB and IIIC melanoma (AJCC 7th Edition) with palpable nodal disease. Patients received vemurafenib 960mg PO BID and cobimetinib 60mg PO OD for 4 months prior to resection followed by 8 months of adjuvant therapy post-surgery. CTscans were performed at baseline and before resection and every 6 months for the first 3 years and yearly in year 4 and 5. Biopsies for correlative studies and diagnosis were performed at baseline prior to starting therapy. The primary outcomes were the proportion of patients achieving resectability, radiologic response as per RECIST and the proportion of patients achieving a pCR. Presented here are the LRFS, DMFS, DFS and OS. Results: Twenty-four patients were enrolled and received neoadjuvant vemurafenib and cobimetinib and 21 underwent resection. Following resection and pathological evaluation 12 (57%; 95% CI 34.02-78.18)) patients achieved a pCR, 8 (38%; 95% CI 18.11-61.56) had a partial pathologic response and 1 had no pathologic response. Of the 24 patients, 2 patients (8%) developed local recurrence, 6 patients (25%) developed distant metastasis, and 8 patients (33%) had either local or distant recurrences. 7 patients (29%) died due to metastatic disease. At 60 months, LRFS was 89.5% (76.7-100%), DMFS was 75.0% (59.5-94.5%), DFS was 85.7% (72.0-100%), and OS was 63.9% (95% CI 43.5-93.8). Among total 20 evaluable patients, 17 patients had CR/PR and 3 had PD/SD as best response. There was no significant difference between patients with CR/PR or SD/PD (log-rank p-value = 0.0548) with 48 month survival of 82.4% for CR/PR population compared to 33.3% with SD or PD. Conclusions: In this small phase II study, neoadjuvant vemurafenib and cobimetinib led to a higher LRFS, DMFS, DFS and OS of all resected patients with bulky nodal disease compared to historical survival rates. Clinical trial information: NCT02036086 .

RWD157 Healthcare Resource Utilization and Cost of Care in Patients with BRAF-Mutated Unresectable/Metastatic Melanoma in the US

The objective of this study was to assess healthcare resource utilization (HCRU) and costs associated with treatments for patients with BRAF-mutant (BRAF-m) metastatic melanoma (m-melanoma) in the US.

Patient characteristics and treatment patterns in BRAF-mutated unresectable or metastatic melanoma in the United States: A snapshot from real-world data.

e21506 Background: BRAF mutations are found in 40-60% of patients with unresectable/metastatic melanoma (m-melanoma). Recently, several new BRAF-targeted therapies (TT) have been approved, transforming the treatment landscape for patients with BRAF-mutated (BRAFm) unresectable/m-melanoma. This analysis aimed to describe patient characteristics and treatment patterns in BRAFm unresectable/m-melanoma patients receiving treatment during November 2015-June 2021. Methods: A retrospective analysis using Flatiron Health’s database was conducted. Adult patients with unresectable/m-melanoma who had evidence of the BRAF-V600 activating mutation were included. Patients were indexed at first-line (1L) therapy initiation. Treatments of interest were classified into immuno-oncology (IO) therapies and TT. All analyses were descriptive. Results: 671 unresectable/m-melanoma patients (average age: 62.7 years, 64.1% male) were included. Among them, 64.4% of patients received IO, 34.4% received TT, and 1.2% received IO+TT. In 1L, ipilimumab+nivolumab and dabrafenib+trametinib were the most common IO (50.9%) and TT (71.9%), respectively. The median duration of 1L was 8.0 months (9.7 months in IO and 6.7 months in TT). Among IO-treated patients, 28.5% had Eastern Cooperative Oncology Group (ECOG)≥1, 23.4% had elevated lactate dehydrogenase (LDH) levels, and 4.9% had 3+ metastases identified. Among TT-treated patients, 42.9% had ECOG≥1, 27.3% had elevated LDH, and 7.8% had 3+ metastases identified. Approximately one-third of the patients (n = 204) received their 1L treatment prior to being tested for BRAF mutation; the majority of whom (90.2%) received IO. 273 patients (40.7%) advanced to a second line (2L). In 2L, 14.3% of patients received the same class of therapy as in 1L, 44.7% switched from 1L IO to 2L TT, and 35.2% switched from 1L TT to 2L IO. In 2L, ipilimumab+nivolumab (50.0%) in IO and dabrafenib+trametinib (60.7%) in TT were the most common combinations. The median duration of 2L was 5.0 months (3.7 months in IO and 6.5 months in TT). Conclusions: Despite the recent availability of TT combinations for BRAFm unresectable/m-melanoma, IO is about twice as frequently prescribed than TT in 1L. One-third of the patients received treatment before BRAFm testing results were available and most of them were prescribed IO. These findings along with elevated ECOG scores, the proportion of 3+ metastases, and elevated LDH levels seen in TT patients, suggest TT is often offered to patients with a high disease burden in the current practice settings.

Retreatment and rechallenge with BRAF/MEK inhibitors in patients with metastatic melanoma: Results from the observational study GEM1801.

9547 Background: Most patients with BRAF-mutant melanoma eventually develop resistance to therapy with BRAF/MEK inhibitors and immune-checkpoint blockade. Alternative treatment strategies are required in these patients since further therapy options lack survival benefit. Small series have shown promising activity from re-exposure to BRAF/MEK inhibitors after a treatment free interval of targeted therapy (TT), probably due to regression of resistant tumors and proliferation of clones that maintain sensitivity to BRAF/MEKi. However, prospective evidence for this approach is limited. Here we report the results of 30 patients who received a second course of TT at relapse after adjuvant therapy (retreatment) or after first progression on TT in the advanced setting (rechallenge). Methods: GEM1801 is a prospective observational study from the Spanish Melanoma Group (GEM) including 893 patients with melanoma treated in 37 centers. This is a descriptive analysis of basal characteristics, response rates (RR), progression free survival (PFS) and overall survival (OS) from 30 patients that received retreatment or rechallenge with BRAF/MEKi in GEM1801 study. Results: 4 patients received retreatment and 26 rechallenge. For retreatment, BRAF/MEKi median free interval from end of adjuvant TT to subsequent retreatment was 17.8 months (range: 12.4 - 57.7). RR with retreatment were 25%, with a median PFS and OS of 5.7 and 8.5 months. For rechallenge, RR was 38.5% and median PFS and OS 11.1 and 22.2 months respectively. Patients who were selected for rechallenge had higher complete response (CR) rates to first TT (26.9% vs 20.3%; p= 0.026). Patients who experimented deeper responses with 1st TT in the metastatic setting showed a correlation to longer PFS to 2nd TT with 12-m PFS rates of 66.7% versus 35.7% (HR 9.09 [95%CI: 1.42-58]; p= 0.02). OS showed a not statistically significant improvement in patients who reported CR to first TD (24-m OS rate of 75% versus 40.7% respectively). BRAF/MEKi free interval since first progression and retreatment or rechallenge was not associated with prognosis. Prognostic factors as LDH and number of metastatic sites did not correlate with the efficacy of retreatment. Conclusions: Retreatment or rechallenge with BRAF/MEKi in the metastatic setting achieved encouraging efficacy and may be a valid therapeutic strategy in a selected group of patients. Response to first treatment, retreatment and rechallenge with BRAF/MEKi. Clinical trial information: NCT03605771 . [Table: see text]

Long-term efficacy of BRAFi/MEKi rechallenge in metastatic melanoma: Report of 9 years of clinical practice.

e21550 Background: First line BRAFi/MEKi therapy in metastatic melanoma eventually result in drug resistance and disease progression. Because drug resistance develops at least partially by epigenetic mechanisms, it may potentially be reversed after BRAFi/MEKi discontinuation. Therefore we aim to explore the clinical efficacy of BRAFi/MEKi rechallenge in 3 line treatment. Moreover the reports on the efficacy of BRAFi/MEKi after immunotherapy were contradictory, so we enrolled patients treated sequentially to explore this clinical scenario. Methods: In country-wide multicenter retrospective analysis 86 patients with metastatic BRAF-mutated melanoma were enrolled since 1/Jan/2014. Patients were treated with 1st line BRAFi/MEKi, 2nd line immunotherapy (anti-PD-1 or anti-CTLA-4) and were rechallenged with BRAFi/MEKi. Survival analyses were performed using the Kaplan-Meier method, log-rank and chi-square tests were used for comparison between groups. Data cut-off was 31/Dec/2022. Results: Median age at BRAFi/MEKi rechallenge was 50 (range: 20-81 y/o). Median overall survival (OS) from the start of the first BRAFi/MEKi therapy and from rechallenge BRAFi/MEKi treatment was 34 and 9 months, respectively; whereas median progression-free survival (PFS) was 10.5 and 4.4 months respectively. At the time of analysis 88% progressed on third line therapy and 78% patients died. Six-month, one-year, and two-year OS rates were: 99%, 93% and 70% on first line treatment; and 65%, 40% and 2% on BRAFi/MEKi rechallenge. Objective response rate and disease control rate on first line BRAFi/MEKi and rechallenge were 57% and 28%; and 91% and 64%, respectively. A lower toxicity rate was noted with BRAFi/MEKi rechallenge. The most common treatment sequence was dabrafenib/trametinib – immunotherapy – encorafenib/binimetinib. Conclusions: Rechallenge with BRAFi/MEKi after second line immunotherapy results in a clinically significant benefit in majority of eligible patients. Third line treatment should be considered for fit patients. [Table: see text]

Kinetics of RTK activation determine ERK reactivation and resistance to dual BRAF/MEK inhibition in melanoma

The combination of BRAF and MEK inhibitors (BRAFi/MEKi) has shown promising response rates in treating BRAF-mutant melanoma by inhibiting ERK activation. However, treatment efficacy is limited by the emergence of drug-tolerant persister cells (persisters). Here, we show that the magnitude and duration of receptor tyrosine kinase (RTK) activation determine ERK reactivation and persister development. Our single-cell analysis reveals that only a small subset of melanoma cells exhibits effective RTK and ERK activation and develops persisters, despite uniform external stimuli. The kinetics of RTK activation directly influence ERK signaling dynamics and persister development. These initially rare persisters form major resistant clones through effective RTK-mediated ERK activation. Consequently, limiting RTK signaling suppresses ERK activation and cell proliferation in drug-resistant cells. Our findings provide non-genetic mechanistic insights into the role of heterogeneity in RTK activation kinetics in ERK reactivation and BRAFi/MEKi resistance, suggesting potential strategies for overcoming drug resistance in BRAF-mutant melanoma.

TERT Expression Induces Resistance to BRAF and MEK Inhibitors in BRAF-Mutated Melanoma In Vitro.

Because BRAF-mutated melanomas are addicted to the Mitogen Activated Protein Kinase (MAPK) pathway they show a high response rate to BRAF and MEK inhibitors. However, the clinical responses to these inhibitors are often short-lived with the rapid onset of resistance to treatment. Deciphering the molecular mechanisms driving resistance has been the subject of intense research. Recent in vitro and clinical data have suggested a link between expression of telomerase and resistance to targeted therapy in melanoma. TERT promoter mutations are the main mechanism for the continuous upregulation of telomerase in melanoma and co-occur frequently with BRAF alterations. To understand how TERT promoter mutations could be associated with resistance to targeted therapy in melanoma, we conducted translational and in vitro studies. In a cohort of V600E-BRAF-mutated melanoma patients, we showed that the TERT promoter mutation status and TERT expression tended to be associated with response to BRAF and MEK inhibitors. We demonstrated that TERT overexpression in BRAF-mutated melanoma cells reduced sensitivity to BRAF and MEK independently of TERT's telomer maintenance activity. Interestingly, inhibition of TERT reduced growth of BRAF-mutated melanoma including resistant cells. TERT expression in melanoma can therefore be a new biomarker for resistance to MAPK inhibitors as well as a novel therapeutic target.

Phase 1 study of the pan-RAF inhibitor tovorafenib in patients with advanced solid tumors followed by dose expansion in patients with metastatic melanoma

PurposeGenomic alterations of BRAF and NRAS are oncogenic drivers in malignant melanoma and other solid tumors. Tovorafenib is an investigational, oral, selective, CNS-penetrant, small molecule, type II pan‑RAF inhibitor. This first-in-human phase 1 study explored the safety and antitumor activity of tovorafenib.MethodsThis two-part study in adult patients with relapsed or refractory advanced solid tumors included a dose escalation phase and a dose expansion phase including molecularly defined cohorts of patients with melanoma. Primary objectives were to evaluate the safety of tovorafenib administered once every other day (Q2D) or once weekly (QW), and to determine the maximum-tolerated and recommended phase 2 dose (RP2D) on these schedules. Secondary objectives included evaluation of antitumor activity and tovorafenib pharmacokinetics.ResultsTovorafenib was administered to 149 patients (Q2D n = 110, QW n = 39). The RP2D of tovorafenib was defined as 200 mg Q2D or 600 mg QW. In the dose expansion phase, 58 (73%) of 80 patients in Q2D cohorts and 9 (47%) of 19 in the QW cohort had grade ≥ 3 adverse events. The most common of these overall were anemia (14 patients, 14%) and maculo-papular rash (8 patients, 8%). Responses were seen in 10 (15%) of 68 evaluable patients in the Q2D expansion phase, including in 8 of 16 (50%) patients with BRAF mutation-positive melanoma naïve to RAF and MEK inhibitors. In the QW dose expansion phase, there were no responses in 17 evaluable patients with NRAS mutation-positive melanoma naïve to RAF and MEK inhibitors; 9 patients (53%) had a best response of stable disease. QW dose administration was associated with minimal accumulation of tovorafenib in systemic circulation in the dose range of 400–800 mg.ConclusionsThe safety profile of both schedules was acceptable, with QW dosing at the RP2D of 600 mg QW preferred for future clinical studies. Antitumor activity of tovorafenib in BRAF-mutated melanoma was promising and justifies continued clinical development across multiple settings.ClinicalTrials.gov identifierNCT01425008.

Ccr2+ Monocyte-Derived Macrophages Influence Trajectories of Acquired Therapy Resistance in Braf-Mutant Melanoma.

Ccr2+ melanoma macrophages that are active in tumors during the drug-tolerant persister state following targeted therapy-induced regression are key contributors directing melanoma cell reprogramming toward specific therapeutic resistance trajectories.

Abstract A010: Using oncogenic pathway agonism to sensitize RAS-mutant cancers to immunotherapy

Abstract Overall, some 30% of human cancers are driven by mutant RAS proteins, which have proven relatively difficult to target. While immunotherapy is effective for NRAS-mutant melanoma, no options exist for resistant disease, and mutant KRAS-driven lung and pancreatic carcinomas are much less responsive overall. Oncogenic pathways are often key targets for inhibition. However, pathway agonism has not been systematically explored as a therapeutic approach. BRAF-mutant melanomas respond to BRAF inhibitors (BRAFi) due to decreased ERK signaling. They can recover signaling by acquiring activating RAS/MEK mutations, but exhibit decreased proliferation in the absence of inhibitor, suggesting that supraphysiologic ERK signaling also compromises fitness. In line with this, we observed that increasing ERK hyperactivation in RAS-mutant cancers, particularly in those with a high ERK activity, might elevate ERK signaling to a degree to induce senescence and also create an inflammatory tumor microenvironment. We have shown that a majority of RAS-mutant cancer cell lines we tested undergo senescence-like arrest following exposure to all FDA-approved BRAF inhibitors at clinically relevant doses. Simultaneous MEK or ERK inhibition allows the cells to recover proliferation, and a BRAFi which does not induce ERK activation fails to have any effect, confirming that ERK hyperactivation is the key driver of this response. Importantly, these findings generalize across NRAS-mutant and KRAS-mutant cancer cell lines including in fresh human pancreatic adenocarcinoma explants. Finally, our data in two novel genomically-characterized, immunocompetent models of NRAS-mutant melanoma and KRAS-mutant pancreatic adenocarcinoma support our in-vitro findings. Both RAS-mutant murine models demonstrate that anti-PD1 therapy is substantially more efficacious when mice are additionally treated with BRAFi. Molecular profiling of the tumor microenvironment reveals the expression of cytokines related to senescence and marked infiltration of activated CD8+ T-cells. In order to implement more potentially effective immunotherapies, we have analyzed the expression of different immune-checkpoint molecules and we have observed a high expression of LAG3 and TIM3 in the melanoma NRAS-mutant model. We will further analyze the effect of those checkpoints in combination with BRAFi to potentiate the anti-tumoral responses and tumor regression. We propose that oncogenic pathway agonism is a novel, effective, and untested strategy to induce proliferation arrest and sensitization to immunotherapy. The impact of this data is in the ability to broadly sensitize RAS-mutant cancers to immunotherapy in the settings of de-novo and acquired resistance. The direct connection between a tumor cell signaling vulnerability to immunotherapy response is a major point of novelty and provides a clear molecular rationale for pursuing combined targeted and immune-based therapy. Citation Format: Alvaro de Mingo Pulido, Charles Adelmann, Brittney Sell, Karol Prieto, Kimberly Nguyen, Cynthia Dixey, Ivannie Ortiz-Rivera, Marco Napoli, Elsa Flores, Jason Fleming, Karen Mann, Christin Burd, Kenneth Y. Tsai. Using oncogenic pathway agonism to sensitize RAS-mutant cancers to immunotherapy [abstract]. In: Proceedings of the AACR Special Conference: Targeting RAS; 2023 Mar 5-8; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Res 2023;21(5_Suppl):Abstract nr A010.

Prognostic and predictive value of metformin in the European Organisation for Research and Treatment of Cancer 1325/KEYNOTE-054 phase III trial of pembrolizumab versus placebo in resected high-risk stage III melanoma

BackgroundMetformin is a commonly prescribed and well-tolerated medication. In laboratory studies, metformin suppresses BRAF wild-type melanoma cells but accelerates the growth of BRAF-mutated cells. This study investigated the prognostic and predictive value of metformin, including with respect to BRAF mutation status, in the European Organisation for Research and Treatment of Cancer 1325/KEYNOTE-054 randomised controlled trial. MethodsPatients with resected high-risk stage IIIA, IIIB, or IIIC melanoma received 200 mg of pembrolizumab (n = 514) or placebo (n = 505) every 3 weeks for twelve months. Pembrolizumab prolonged recurrence-free survival (RFS) and distant metastasis-free survival (DMFS) at approximately 42 months median follow-up (Eggermont et al., TLO, 2021). Multivariable Cox regression was used to estimate associations of metformin with RFS and DMFS. Interaction terms were used to model effect modification by treatment and BRAF mutation. ResultsFifty-four patients (0.5%) used metformin at baseline. Metformin was not significantly associated with RFS (hazard ratio [HR] 0.87, 95% confidence interval [CI] 0.52–1.45) and DMFS (HR 0.82, 95% CI 0.47–1.44). The interaction between metformin and the treatment arm was not significant for either RFS (p = 0.92) or DMFS (p = 0.93). Among patients with mutated BRAF, the association of metformin with RFS (HR 0.70, 95% CI 0.37–1.33) was greater in magnitude though not significantly different to those without mutated BRAF (HR 0.98, 95% CI 0.56–1.69). ConclusionsThere was no significant impact of metformin use on pembrolizumab efficacy in resected high-risk stage III melanoma. However, larger studies or pooled analyses are needed, particularly to explore a possible effect of metformin in BRAF-mutated melanoma.

Sustained release hydrogel for durable locoregional chemoimmunotherapy for BRAF-mutated melanoma

The wide prevalence of BRAF mutations in diagnosed melanomas drove the clinical advancement of BRAF inhibitors in combination with immune checkpoint blockade for treatment of advanced disease. However, deficits in therapeutic potencies and safety profiles motivate the development of more effective strategies that improve the combination therapy's therapeutic index. Herein, we demonstrate the benefits of a locoregional chemoimmunotherapy delivery system, a novel thermosensitive hydrogel comprised of gelatin and Pluronic® F127 components already widely used in humans in both commercial and clinical products, for the co-delivery of a small molecule BRAF inhibitor with immune checkpoint blockade antibody for the treatment of BRAF-mutated melanoma. In vivo evaluation of administration route and immune checkpoint target effects revealed intratumoral administration of antagonistic programmed cell death protein 1 antibody (aPD-1) lead to potent antitumor therapy in combination with BRAF inhibitor vemurafenib. The thermosensitive F127-g-Gelatin hydrogel that was evaluated in multiple murine models of BRAF-mutated melanoma that facilitated prolonged local drug release within the tumor (>1 week) substantially improved local immunomodulation, tumor control, rates of tumor response, and animal survival. Thermosensitive F127-g-Gelatin hydrogels thus improve upon the clinical benefits of vemurafenib and aPD-1 in a locoregional chemoimmunotherapy approach for the treatment of BRAF-mutated melanoma.

Reactive Oxygen Species Regulation of Chemoresistance and Metastatic Capacity of Melanoma: Role of the Cancer Stem Cell Marker CD271

BRAF mutations are present in 30-50% of cases of cutaneous melanoma, and treatment with selective BRAF and MEK inhibitors has been introduced. However, the development of resistance to these drugs often occurs. Chemo-resistant melanoma cells show increased expression of CD271, a stem cell marker that features increased migration. Concordantly, resistance to the selective inhibitor of oncogenic BRAFV600E/K, vemurafenib, is mediated by the increased expression of CD271. It has recently been shown that the BRAF pathway leads to an overexpression of the NADPH oxidase Nox4, which produces reactive oxygen species (ROS). Here, we examined in vitro how Nox-derived ROS in BRAF-mutated melanoma cells regulates their drug sensitivity and metastatic potential. We demonstrated that DPI, a Nox inhibitor, reduced the resistance of a melanoma cell line (SK-MEL-28) and a primary culture derived from a BRAFV600E-mutated biopsy to vemurafenib. DPI treatment affected the expression of CD271 and the ERK and Akt signaling pathways, leading to a drop in epithelial-mesenchymal transition (EMT), which undoubtedly promotes an invasive phenotype in melanoma. More importantly, the scratch test demonstrated the efficacy of the Nox inhibitor (DPI) in blocking migration, supporting its use to counteract drug resistance and thus cell invasion and metastasis in BRAF-mutated melanoma.

Pharmacological induction of membrane lipid poly-unsaturation sensitizes melanoma to ROS inducers and overcomes acquired resistance to targeted therapy

BackgroundOne of the key limitations of targeted cancer therapies is the rapid onset of therapy resistance. Taking BRAF-mutant melanoma as paradigm, we previously identified the lipogenic regulator SREBP-1 as a central mediator of resistance to MAPK-targeted therapy. Reasoning that lipogenesis-mediated alterations in membrane lipid poly-unsaturation lie at the basis of therapy resistance, we targeted fatty acid synthase (FASN) as key player in this pathway to evoke an exquisite vulnerability to clinical inducers of reactive oxygen species (ROS), thereby rationalizing a novel clinically actionable combination therapy to overcome therapy resistance.MethodsUsing gene expression analysis and mass spectrometry-based lipidomics of BRAF-mutant melanoma cell lines, melanoma PDX and clinical data sets, we explored the association of FASN expression with membrane lipid poly-unsaturation and therapy-resistance. Next, we treated therapy-resistant models with a preclinical FASN inhibitor TVB-3664 and a panel of ROS inducers and performed ROS analysis, lipid peroxidation tests and real-time cell proliferation assays. Finally, we explored the combination of MAPK inhibitors, TVB-3664 and arsenic trioxide (ATO, as a clinically used ROS-inducer) in Mel006 BRAF mutant PDX as a gold model of therapy resistance and assessed the effect on tumor growth, survival and systemic toxicity.ResultsWe found that FASN expression is consistently increased upon the onset of therapy resistance in clinical melanoma samples, in cell lines and in Mel006 PDX and is associated with decreased lipid poly-unsaturation. Forcing lipid poly-unsaturation in therapy-resistant models by combining MAPK inhibition with FASN inhibition attenuated cell proliferation and rendered cells exquisitely sensitive to a host of ROS inducers. In particular, the triple combination of MAPK inhibition, FASN inhibition, and the clinical ROS-inducing compound ATO dramatically increased survival of Mel006 PDX models from 15 to 72% with no associated signs of toxicity.ConclusionsWe conclude that under MAPK inhibition the direct pharmacological inhibition of FASN evokes an exquisite vulnerability to inducers of ROS by increasing membrane lipid poly-unsaturation. The exploitation of this vulnerability by combining MAPK and/or FASN inhibitors with inducers of ROS greatly delays the onset of therapy resistance and increases survival. Our work identifies a clinically actionable combinatorial treatment for therapy-resistant cancer.