BRAF-mutant Melanoma Research Articles

The Investigation of Hsp90C-Terminal Inhibitors Containing Amide Bioisosteres.

Heat Shock Protein 90 (Hsp90) is responsible for the proper folding and maturation of ~400 client protein substrates, many of which are directly associated with the ten hallmarks of cancer. Hsp90 is a great target for cancer therapy including melanoma, since Hsp90 inhibition can disrupt multiple oncogenic pathways simultaneously. In this study, we report the synthesis and anti-proliferative activity manifested by a series of Hsp90 C-terminal inhibitors against mutant BRAF and wild-type BRAF melanoma cells. Furthermore, we explored structure-activity relationships (SAR) for the amide moiety of 6 (B1), a novel Hsp90C-terminal inhibitor via introduction of amide bioisosteres. Compound 6 displayed an IC50 of 1.01 μM, 0.782 μM, 0.607 μM and 1.413 μM against SKMel173, SKMel103, SKMel19 and A375 cells, respectively.

Cardiovascular effects of BRAF and MEK inhibitors in patients with melanoma: a prospective study incorporating risk scores, cardiac biomarkers and cardiovascular magnetic resonance imaging

Abstract Background BRAF and MEK inhibitors have revolutionised treatment for patients with BRAF-mutated melanoma. Unfortunately, they are associated with cardiovascular adverse effects including hypertension and cancer-therapy related cardiac dysfunction (CTRCD). The ‘real world’ incidence and risk factors for these adverse effects are poorly described. Purpose To characterise the incidence and risk factors for BRAF and MEK inhibitor-associated hypertension and CTRCD in a prospective ‘real world’ setting. Methods Prospective, observational, cohort study of patients with melanoma treated with BRAF and MEK inhibitors at a regional cancer hospital network (March 2021 - May 2023). Comprehensive assessment was performed at baseline, 4, 12 and 24 weeks following start of treatment, including home and clinic blood pressure assessment, serial echocardiography, stress-perfusion cardiovascular magnetic resonance imaging (CMR) and humoral biomarkers (Figure 1). CTRCD was defined as mild, moderate or severe in line with International Cardio-Oncology Society (IC-OS) definitions. Hypertension was defined as 7 day average home blood pressure of ≥135/85 mmHg or the initiation or escalation of anti-hypertensive therapy. Baseline cardiotoxicity risk stratification was performed using the ESC Cardio-Oncology guideline-recommended tool. Results 61 participants were enrolled. 48% developed BRAF/MEK inhibitor associated hypertension. 46% of participants developed CTRCD and, of these, 24 (86%) were classified as mild, 3 (11%) moderate and 1 (3%) severe. Left ventricular ejection fraction (LVEF) during follow up is shown in Figure 2. All participants with moderate and severe CTRCD also had BRAF/MEK inhibitor associated hypertension. After stratification with the baseline risk assessment tool, no patient in the ‘low risk’ group developed moderate or severe CTRCD. Baseline elevated NT-proBNP (>125pg/mL), history of left ventricular systolic dysfunction and atrial fibrillation were associated with the development of CTRCD. 20 participants underwent stress perfusion CMR at baseline, 4 and 24 weeks. 25% had a drop in LVEF to <50% but only 5% had a co-existing LVEF ≥10% from baseline to fulfil criteria for the diagnosis of moderate CTRCD. Conclusion BRAF and MEK inhibitor-associated hypertension and CTRCD is common, with a higher incidence in this ‘real world’ prospective cohort than observed in clinical trials. The majority of CTRCD was ‘mild’ and the long term sequalae of this remains unknown. No patients considered to be at low baseline risk for CTRCD using the ESC-recommended risk stratification tool developed moderate or severe CTRCD. These findings support the use of routine blood pressure surveillance in this group as well as baseline risk stratification to guide appropriate imaging surveillance of cardiac function.Figure 1.Schedule of study visitsFigure 2.LV function/CTRCD over time

Update on the treatment of BRAFmut metastatic melanoma and future perspectives

Abstractv‐Raf murine sarcoma viral oncogene homolog B (BRAF) mutations were first identified in melanoma in 2002, leading to increased cell division and proliferation, and resultant tumour growth. The identification and characterisation of BRAF mutations (BRAFmut) led to the development of several highly specific, BRAF‐, then mitogen‐activated kinase enzyme (MEK)‐targeted therapies that have enabled rapid tumour responses and improved treatment outcomes in most patients with metastatic BRAFmut melanoma. The combination of these two drug classes (BRAF inhibitors and MEK inhibitors) has demonstrated improved response rates, progression‐free survival, and overall survival (OS), along with a more tolerable safety profile, compared with BRAF inhibition alone. In parallel, improved knowledge of the immune system has enabled the development of immune checkpoint inhibitors (ICIs), although immune‐related adverse events with ICIs may prove to be problematic in some patients and require careful management. While targeted therapy appears to provide rapid disease control in a relatively high proportion of patients, the development of secondary resistance may limit the overall duration of responses. Acquired resistance, along with primary resistance, has also been reported for ICIs, with a lower overall response rate to that with targeted therapy, although durable responses have been reported in some responding patients. A combination strategy of targeted therapy with ICIs has demonstrated modest increases in efficacy compared with targeted therapy combinations, although data significance varies across studies, there is increased risk of toxicity, and triple combination therapy has not yet received clinical approval in Europe. Thus, there is an ongoing need to establish optimal sequencing of these treatments in patients with advanced BRAFmut melanoma, and this has become the focus of current research. The aim of this narrative review was to provide an update on the treatment of BRAFmut metastatic melanoma, current guideline recommendations, and future clinical perspectives.

Triple combination of vemurafenib, cobimetinib, and atezolizumab in real clinical practice in the Russian Federation: results of the A1 cohort of the ISABELLA study.

Among several treatment options for BRAF-mutant metastatic melanoma, a combination of BRAF inhibitor, MEK inhibitor, and anti-PDL1 antibody seems to be a new emergent approach recently registered in the Russian Federation. It is still not clear which patient population benefits more from this simultaneous use of three drugs instead of its sequencing. This study aimed to evaluate patients' characteristics treated in real practice in 14 Russian regions by triple combination and to analyze their outcomes depending on biomarkers (PD-L1 expression). This was a part (cohort A1) of a prospective non-interventional study of clinical outcomes and biomarkers in patients with skin melanoma. Patients were included in cohort A1 if combination treatment with vemurafenib (vem) + cobimetinib (cobi) + atezolizumab (atezo) was initiated no earlier than 12 weeks (84 days) prior to written informed consent to participate in this study. The index event was the initiation of therapy with all three drugs vem + cobi + atezo (i.e., triple combination). The primary efficacy endpoint of the study was the 24-month overall survival (OS), defined as the time from the index date to the date of death from any cause. If the patient did not experience an event, the OS will be censored at the date of the last contact. Objective response rate (ORR), duration of response (DoR), and progression-free survival (PFS) in the Intention to treat (ITT) population, in biomarker positive population, and in population with brain metastases were also evaluated. Quality of life questionnaires were pre-planned by protocol if it was a part of routine practice. Adverse events were also collected. Between March 2021 and May 2023, 59 patients were enrolled in 19 centers from 14 regions of Russia. Thirty-one of 59 (52.4%) patients had central nervous system metastases, and 18 of 31 (58.4%) were symptomatic. Forty of 59 patients (68%) received the triple combination as the first-line treatment. The median follow-up period was 16.83 [95% confidence interval (CI) 13.8-19.8] months. The mean duration of therapy with this regimen was 9.95 months (95% CI 7.48-13.8). ORR was 55.1%; progression as the best outcome was seen in 16.3%. The median DoR was 12.95 months (95% CI 11.0-14.8 months), with a median of 20.3 months (95% CI 9.1-31.5 months) when triple therapy was administered in the first-line treatment. In patients with brain metastases (N = 31), ORR was 45.1%; the median DoR was 12.95 (95% CI 11.0-14.8 months). The median PFS in the entire population was 13.6 months (95% CI 8.6-18.6); the 24-month PFS was 22%. The estimated median OS in the entire population was 15.8 months (95% CI NA); 24-month OS was 45% (95% CI 0.32-0.64). In multivariate Cox regression model, biomarkers of interest [lactate dehydrogenase, Programmed cell death ligand-1 (PD-L1)] did not have statistically significant impact on PFS, OS, or DoR probably due to high data missing rate. No unexpected adverse events were reported. Grades 3-4 AEs were seen in 23 of 59 patients (38%) with most common were skin and liver toxicity. Triple combination of atezolizumab, vemurafenib, and cobimetinib had proven its efficacy and tolerability in real settings. No impact of potential predictive biomarkers was seen (NCT05402059).

Inhibition and degradation of NRAS with a pan-NRAS monobody.

The RAS family GTPases are the most frequently mutated oncogene family in human cancers. Activating mutations in either of the three RAS isoforms (HRAS, KRAS, or NRAS) are found in nearly 20% of all human tumors with NRAS mutated in ~25% of melanomas. Despite remarkable advancements in therapies targeted against mutant KRAS, NRAS-specific pharmacologics are lacking. Thus, development of inhibitors of NRAS would address a critical unmet need to treating primary tumors harboring NRAS mutations as well as BRAF-mutant melanomas, which frequently develop resistance to clinically approved BRAF inhibitors through NRAS mutation. Building upon our previous studies with the monobody NS1 that recognizes HRAS and KRAS but not NRAS, here we report the development of a monobody that specifically binds to both GDP and GTP-bound states of NRAS and inhibits NRAS-mediated signaling in a mutation-agnostic manner. Further, this monobody can be formatted into a genetically encoded NRAS-specific degrader. Our study highlights the feasibility of developing NRAS selective inhibitors for therapeutic efforts.

The development of drug resistance in metastatic tumours under chemotherapy: An evolutionary perspective

We present a mathematical model of the evolutionary dynamics of a metastatic tumour under chemotherapy, comprising non-local partial differential equations for the phenotype-structured cell populations in the primary tumour and its metastasis. These equations are coupled with a physiologically-based pharmacokinetic model of drug administration and distribution, implementing a realistic delivery schedule. The model is carefully calibrated from the literature, focusing on BRAF-mutated melanoma treated with Dabrafenib as a case study. By means of long-time asymptotic and global sensitivity analyses, as well as numerical simulations, we explore the impact of cell migration from the primary to the metastatic site, physiological aspects of the tumour tissues and drug dose on the development of chemoresistance and treatment efficacy. Our findings provide a possible explanation for empirical evidence indicating that chemotherapy may foster metastatic spread and that metastases may be less impacted by the chemotherapeutic agent.

Cost-effectiveness of treatment sequences for BRAF-mutant advanced melanoma in the Netherlands using a health economic model

BackgroundThis study aims to evaluate the cost-effectiveness of treatment sequences for patients with advanced melanoma with a BRAF mutation in the Netherlands from a societal perspective. MethodsA semi-Markov model with a life-time horizon has been used to evaluate cost-effectiveness of 21 treatment sequences. Real-world data from the Dutch Melanoma Treatment Registry (DMTR) were used to estimate time to progression, next treatment and death. Utilities by health state as well as hospital costs, health care costs outside the hospital, patient and family costs and productivity costs were also derived from the DMTR. Drug costs were estimated based on the recommended dose and duration of treatment. Incremental cost-effectiveness ratios (ICERs) were presented as incremental costs per QALY gained. ResultsHealth benefits of treatment sequences consisting of targeted therapies and immunotherapies vary between 2.3 and 5.8 QALYs gained per patient when compared to chemotherapy. The increase in costs varies between €112,000 and €383,000. The efficiency frontier consists of nivolumab in the first line followed by ipilimumab in the second line (ICERs of €42,000/QALY and €44,000/QALY), nivolumab in the first line followed by encorafenib plus binimetinib in the second line (ICERs of €71,000/QALY and €68,000/QALY) and nivolumab plus ipilimumab in the first line followed by encorafenib plus binimetinib in the second line (ICERs of €74,000/QALY and €76,000/QALY). The first treatment given within a sequence as well as assumptions regarding treatment duration have a substantial impact on cost-effectiveness outcomes. ConclusionThe ICERs can be considered cost-effective at different cost-effectiveness thresholds.

Strongly ROS-Correlated, Time-Dependent, and Selective Antiproliferative Effects of Synthesized Nano Vesicles on BRAF Mutant Melanoma Cells and Their Hyaluronic Acid-Based Hydrogel Formulation.

Cutaneous metastatic melanoma (CMM) is the most aggressive form of skin cancer with a poor prognosis. Drug-induced secondary tumorigenesis and the emergency of drug resistance worsen an already worrying scenario, thus rendering urgent the development of new treatments not dealing with mutable cellular processes. Triphenyl phosphonium salts (TPPSs), in addiction to acting as cytoplasmic membrane disruptors, are reported to be mitochondria-targeting compounds, exerting anticancer effects mainly by damaging their membranes and causing depolarization, impairing mitochondria functions and their DNA, triggering oxidative stress (OS), and priming primarily apoptotic cell death. TPP-based bola amphiphiles are capable of self-forming nanoparticles (NPs) with enhanced biological properties, as commonly observed for nanomaterials. Already employed in several other biomedical applications, the per se selective potent antibacterial effects of a TPP bola amphiphile have only recently been demonstrated on 50 multidrug resistant (MDR) clinical superbugs, as well as its exceptional and selective anticancer properties on sensitive and MDR neuroblastoma cells. Here, aiming at finding new molecules possibly developable as new treatments for counteracting CMM, the effects of this TPP-based bola amphiphile (BPPB) have been investigated against two BRAF mutants CMM cell lines (MeOV and MeTRAV) with excellent results (even IC50 = 49 nM on MeOV after 72 h treatment). With these findings and considering the low cytotoxicity of BPPB against different mammalian non-tumoral cell lines and red blood cells (RBCs, selectivity indexes up to 299 on MeOV after 72 h treatment), the possible future development of BPPB as topical treatment for CMM lesions was presumed. With this aim, a biodegradable hyaluronic acid (HA)-based hydrogel formulation (HA-BPPB-HG) was prepared without using any potentially toxic crosslinking agents simply by dispersing suitable amounts of the two ingredients in water and sonicating under gentle heating. HA-BPPB-HA was completely characterized, with promising outcomes such as high swelling capability, high porosity, and viscous elastic rheological behavior.

Advancements and Challenges in Personalized Therapy for BRAF-Mutant Melanoma: A Comprehensive Review.

Over the past several decades, advancements in the treatment of BRAF-mutant melanoma have led to the development of BRAF inhibitors, BRAF/MEK inhibitor combinations, anti-PD-1 therapy, and anti-CTLA4 therapy. Although these therapies have shown substantial efficacy in clinical trials, their sustained effectiveness is often challenged by the tumor microenvironment, which is a highly heterogeneous and complex milieu of immunosuppressive cells that affect tumor progression. The era of personalized medicine holds substantial promise for the tailoring of treatments to individual genetic profiles. However, tumor heterogeneity and immune evasion mechanisms contribute to the resistance to immunotherapy. Despite these challenges, tumor-infiltrating lymphocyte (TIL) therapy, as exemplified by lifileucel, has demonstrated notable efficacy against BRAF V600-mutant melanoma. Additionally, early response biomarkers, such as COX-2 and MMP2, along with FDG-PET imaging, offer the potential to improve personalized immunotherapy by predicting patient responses and determining the optimal treatment duration. Future efforts should focus on reducing the T-cell harvesting periods and costs associated with TIL therapy to enhance efficiency and accessibility.

Adjuvant Therapy in Acral Melanoma: A Systematic Review.

Acral melanoma presents distinct biological characteristics compared to cutaneous melanoma. While adjuvant therapeutic strategies for high-risk resected acral melanoma closely resemble those for cutaneous melanoma, the evidence supporting the clinical application of adjuvant therapy for acral melanoma remains inadequate. Our aim was to systematically analyze the efficacy and safety profile of adjuvant therapy in acral melanoma. This systematic review adhered to a pre-registered protocol. We comprehensively searched four electronic databases and reference lists of included articles to identify eligible studies. The primary outcome was therapeutic efficacy, and the secondary outcome was adverse events (AEs). This systematic review included 11 studies with 758 acral melanoma patients undergoing adjuvant therapy. High-dose interferon α-2b (IFN) regimens showed no significant difference in recurrence-free survival (RFS), though the longer regimen was linked to increased hepatotoxicity. Adjuvant anti-PD-1 therapy demonstrated varying efficacy, with improved RFS in patients who experienced immune-related AEs. Targeted therapy with dabrafenib plus trametinib achieved high 12-month RFS in patients with BRAF-mutated acral melanoma. Comparative studies suggested that adjuvant anti-PD-1 therapy is similarly effective to IFN in prolonging survival for high-risk acral melanoma patients. Additionally, prior treatment with pegylated IFN enhanced RFS in patients receiving adjuvant pembrolizumab. High-dose IFN was widely used as adjuvant therapy for acral melanoma, but serious AEs prompted the search for alternatives. Adjuvant anti-PD-1 therapy shows promise, though it may be less effective than in non-acral melanoma. Further prospective studies are needed to determine the optimal adjuvant treatment for acral melanoma.

Multi-omics analysis delineates resistance mechanisms associated with BRAF inhibition in melanoma cells

Mutant BRAF is a critical oncogenic driver in melanoma, making it an attractive therapeutic target. However, the success of targeted therapy using BRAF inhibitors vemurafenib and dabrafenib has been limited due to development of resistance, restricting their clinical efficacy. A prior knowledge of resistance mechanisms to BRAFi or any cancer drug can lead to development of drugs that overcome resistance thus improving clinical outcomes. In vitro cellular models are powerful systems that can be utilized to mimic and study resistance mechanisms. In this study, we employed a multi-omics approach to characterize a panel of BRAF mutant melanoma cell lines to develop and systematically characterize BRAFi persister and resistant cells using exome sequencing, proteomics and phosphoproteomics. Our datasets revealed frequently observed intrinsic and acquired, genetic and non-genetic mechanisms of BRAFi resistance that have been studied in patients who developed resistance. In addition, we identified proteins that can be potentially targeted to overcome BRAFi resistance. Overall, we demonstrate that in vitro systems can be utilized not only to predict resistance mechanisms but also to identify putative therapeutic targets.

Computational Modeling of Drug Response Identifies Mutant-Specific Constraints for Dosing panRAF and MEK Inhibitors in Melanoma.

This study explores the potential of pre-clinical in vitro cell line response data and computational modeling in identifying the optimal dosage requirements of pan-RAF (Belvarafenib) and MEK (Cobimetinib) inhibitors in melanoma treatment. Our research is motivated by the critical role of drug combinations in enhancing anti-cancer responses and the need to close the knowledge gap around selecting effective dosing strategies to maximize their potential. In a drug combination screen of 43 melanoma cell lines, we identified specific dosage landscapes of panRAF and MEK inhibitors for NRAS vs. BRAF mutant melanomas. Both experienced benefits, but with a notably more synergistic and narrow dosage range for NRAS mutant melanoma (mean Bliss score of 0.27 in NRAS vs. 0.1 in BRAF mutants). Computational modeling and follow-up molecular experiments attributed the difference to a mechanism of adaptive resistance by negative feedback. We validated the in vivo translatability of in vitro dose-response maps by predicting tumor growth in xenografts with high accuracy in capturing cytostatic and cytotoxic responses. We analyzed the pharmacokinetic and tumor growth data from Phase 1 clinical trials of Belvarafenib with Cobimetinib to show that the synergy requirement imposes stricter precision dose constraints in NRAS mutant melanoma patients. Leveraging pre-clinical data and computational modeling, our approach proposes dosage strategies that can optimize synergy in drug combinations, while also bringing forth the real-world challenges of staying within a precise dose range. Overall, this work presents a framework to aid dose selection in drug combinations.

Non-coding RNAs in BRAF-mutant melanoma: targets, indicators, and therapeutic potential.

Melanoma, a highly aggressive skin cancer, is often driven by BRAF mutations, such as the V600E mutation, which promotes cancer growth through the MAPK pathway and contributes to treatment resistance. Understanding the role of non-coding RNAs (ncRNAs) in these processes is crucial for developing new therapeutic strategies. This review aims to elucidate the relationship between ncRNAs and BRAF mutations in melanoma, focusing on their regulatory roles and impact on treatment resistance. We comprehensively reviewed current literature to synthesize evidence on ncRNA-mediated regulation of BRAF-mutant melanoma and their influence on therapeutic responses. Key ncRNAs, including microRNAs and long ncRNAs, were identified as significant regulators of melanoma development and therapy resistance. MicroRNAs such as miR-15/16 and miR-200 families modulate critical pathways like Wnt signaling and melanogenesis. Long ncRNAs like ANRIL and SAMMSON play roles in cell growth, invasion, and drug susceptibility. Specific ncRNAs, such as BANCR and RMEL3, intersect with the MAPK pathway, highlighting their potential as therapeutic targets or biomarkers in BRAF-mutant melanoma. Additionally, ncRNAs involved in drug resistance, such as miR-579-3p and miR-1246, target processes like autophagy and immune checkpoint regulation. This review highlights the pivotal roles of ncRNAs in regulating BRAF-mutant melanoma and their contribution to drug resistance. These findings underscore the potential of ncRNAs as biomarkers and therapeutic targets, paving the way for innovative treatments to improve outcomes for melanoma patients.

First-Line Nivolumab Plus Relatlimab Versus Nivolumab Plus Ipilimumab in Advanced Melanoma: An Indirect Treatment Comparison Using RELATIVITY-047 and CheckMate 067 Trial Data.

Nivolumab plus relatlimab and nivolumab plus ipilimumab have been approved for advanced melanoma on the basis of the phase II/III RELATIVITY-047 and phase III CheckMate 067 trials, respectively. As no head-to-head trial comparing these regimens exists, an indirect treatment comparison was conducted using patient-level data from each trial. Inverse probability of treatment weighting (IPTW) adjusted for baseline characteristic differences. Minimum follow-ups (RELATIVITY-047, 33 months; CheckMate 067, 36 months) were selected to best align assessments. Outcomes included progression-free survival (PFS), confirmed objective response rate (cORR), and melanoma-specific survival (MSS) per investigator; overall survival (OS); and treatment-related adverse events (TRAEs). A Cox regression model compared PFS, OS, and MSS. A logistic regression model compared cORRs. Subgroup analyses were exploratory. After IPTW, key baseline characteristics were balanced for nivolumab plus relatlimab (n = 339) and nivolumab plus ipilimumab (n = 297). Nivolumab plus relatlimab demonstrated similar PFS (hazard ratio [HR], 1.08 [95% CI, 0.88 to 1.33]), cORR (odds ratio, 0.91 [95% CI, 0.73 to 1.14]), OS (HR, 0.94 [95% CI, 0.75 to 1.19]), and MSS (HR, 0.86 [95% CI, 0.67 to 1.12]) to nivolumab plus ipilimumab. Subgroup comparisons showed larger numerical differences favoring nivolumab plus ipilimumab with acral melanoma, BRAF-mutant melanoma, and lactate dehydrogenase >2 × upper limit of normal, but were limited by small samples. Nivolumab plus relatlimab was associated with fewer grade 3-4 TRAEs (23% v 61%) and any-grade TRAEs leading to discontinuation (17% v 41%). Nivolumab plus relatlimab demonstrated similar efficacy to nivolumab plus ipilimumab in the overall population, including most-but not all-subgroups, and improved safety in patients with untreated advanced melanoma. Results should be interpreted with caution.

Computational modeling of drug response identifies mutant-specific constraints for dosing panRAF and MEK inhibitors in melanoma.

This study explores the potential of preclinical in vitro cell line response data and computational modeling in identifying optimal dosage requirements of pan-RAF (Belvarafenib) and MEK (Cobimetinib) inhibitors in melanoma treatment. Our research is motivated by the critical role of drug combinations in enhancing anti-cancer responses and the need to close the knowledge gap around selecting effective dosing strategies to maximize their potential. In a drug combination screen of 43 melanoma cell lines, we identified unique dosage landscapes of panRAF and MEK inhibitors for NRAS vs BRAF mutant melanomas. Both experienced benefits, but with a notably more synergistic and narrow dosage range for NRAS mutant melanoma. Computational modeling and molecular experiments attributed the difference to a mechanism of adaptive resistance by negative feedback. We validated in vivo translatability of in vitro dose-response maps by accurately predicting tumor growth in xenografts. Then, we analyzed pharmacokinetic and tumor growth data from Phase 1 clinical trials of Belvarafenib with Cobimetinib to show that the synergy requirement imposes stricter precision dose constraints in NRAS mutant melanoma patients. Leveraging pre-clinical data and computational modeling, our approach proposes dosage strategies that can optimize synergy in drug combinations, while also bringing forth the real-world challenges of staying within a precise dose range.

Novel gene therapy for drug-resistant melanoma: Synergistic combination of PTEN plasmid and BRD4 PROTAC-loaded lipid nanocarriers

Patients suffering from BRAF mutant melanoma have tumor recurrence within merely 7 months of treatment with a potent BRAF inhibitor (BRAFi) like vemurafenib (VEM). It has been proven that diverse molecular pathways driving BRAFi resistance converge to activation of c-Myc in melanoma. Therefore, we identified a novel combinatorial therapeutic strategy by targeting loss of PTEN tumor suppressor gene and upregulated BRD4 oncoprotein as Myc-dependent vulnerabilities of drug-resistant melanoma. Being promising therapeutic targets, we decided to concomitantly deliver PTEN plasmid and BRD4 targeted PROteolysis-TArgeting Chimera (ARV) to drug the “undruggable” c-Myc in BRAFi-resistant melanoma. Since PTEN plasmid and ARV are distinct in their physicochemical properties, we fabricated PTEN-plasmid loaded LNPs (PL-NANO) and ARV-825 loaded nanoliposomes (AL-NANO) to yield mean particle size of <100 nm and >99% encapsulation efficiency for each therapeutic payload. Combination of PL-NANO and AL-NANO displayed synergistic tumor growth inhibition and substantial apoptosis in in vitro 2D and 3D models. Importantly, simultaneous delivery of PL-NANO and AL-NANO achieved significant upregulation of PTEN expression levels and degradation of BRD4 protein to ultimately downregulate c-Myc levels in BRAFi-resistant melanoma cells. Altogether, lipid nanocarriers delivering this novel lethal cocktail stands as “one-of-a-kind” gene therapy to target “undruggable” c-Myc oncogene in BRAFi-resistant melanoma.

Synthetic RIG-I agonist-mediated cancer immunotherapy synergizes with MAP kinase inhibition against BRAF-mutated melanoma

The implementation of targeted molecular therapies and immunotherapy in melanoma vastly improved the therapeutic outcome in patients with limited efficacy of surgical intervention. Nevertheless, a large fraction of patients with melanoma still remain refractory or acquire resistance to these new forms of treatment, illustrating a need for improvement. Here, we report that the clinically relevant combination of mitogen-activated protein (MAP) kinase pathway inhibitors dabrafenib and trametinib synergize with RIG-I agonist-induced immunotherapy to kill BRAF-mutated human and mouse melanoma cells. Kinase inhibition did not compromise the agonist-induced innate immune response of the RIG-I pathway in host immune cells. In a melanoma transplantation mouse model, the triple therapy outperformed individual therapies. Our study suggests that agonist-induced activation of RIG-I with its synthetic ligand 3pRNA could vastly improve tumor control in a substantial fraction of patients with melanoma receiving MAP kinase inhibitors.

Polyamine and EIF5A hypusination downstream of c-Myc confers targeted therapy resistance in BRAF mutant melanoma

BackgroundBRAF inhibitors are widely employed in the treatment of melanoma with the BRAF V600E mutation. However, the development of resistance compromises their therapeutic efficacy. Diverse genomic and transcriptomic alterations are found in BRAF inhibitor resistant melanoma, posing a pressing need for convergent, druggable target that reverse therapy resistant tumor with different resistance mechanisms.MethodsCRISPR-Cas9 screens were performed to identify novel target gene whose inhibition selectively targets A375VR, a BRAF V600E mutant cell line with acquired resistance to vemurafenib. Various in vitro and in vivo assays, including cell competition assay, water soluble tetrazolium (WST) assay, live-dead assay and xenograft assay were performed to confirm synergistic cell death. Liquid Chromatography-Mass Spectrometry analyses quantified polyamine biosynthesis and changes in proteome in vemurafenib resistant melanoma. EIF5A hypusination dependent protein translation and subsequent changes in mitochondrial biogenesis and activity were assayed by O-propargyl-puromycin labeling assay, mitotracker, mitoSOX labeling and seahorse assay. Bioinformatics analyses were used to identify the association of polyamine biosynthesis with BRAF inhibitor resistance and poor prognosis in melanoma patient cohorts.ResultsWe elucidate the role of polyamine biosynthesis and its regulatory mechanisms in promoting BRAF inhibitor resistance. Leveraging CRISPR-Cas9 screens, we identify AMD1 (S-adenosylmethionine decarboxylase 1), a critical enzyme for polyamine biosynthesis, as a druggable target whose inhibition reduces vemurafenib resistance. Metabolomic and proteomic analyses reveal that polyamine biosynthesis is upregulated in vemurafenib-resistant cancer, resulting in enhanced EIF5A hypusination, translation of mitochondrial proteins and oxidative phosphorylation. We also identify that sustained c-Myc levels in vemurafenib-resistant cancer are responsible for elevated polyamine biosynthesis. Inhibition of polyamine biosynthesis or c-Myc reversed vemurafenib resistance both in vitro cell line models and in vivo in a xenograft model. Polyamine biosynthesis signature is associated with poor prognosis and shorter progression free survival after BRAF/MAPK inhibitor treatment in melanoma cohorts, highlighting the clinical relevance of our findings.ConclusionsOur findings delineate the molecular mechanisms involving polyamine-EIF5A hypusination-mitochondrial respiration pathway conferring BRAF inhibitor resistance in melanoma. These targets will serve as effective therapeutic targets that can maximize the therapeutic efficacy of existing BRAF inhibitors.

Purinergic Ca2+ Signaling as a Novel Mechanism of Drug Tolerance in BRAF-Mutant Melanoma.

Drug tolerance is a major cause of relapse after cancer treatment. Despite intensive efforts, its molecular basis remains poorly understood, hampering actionable intervention. We report a previously unrecognized signaling mechanism supporting drug tolerance in BRAF-mutant melanoma treated with BRAF inhibitors that could be of general relevance to other cancers. Its key features are cell-intrinsic intracellular Ca2+ signaling initiated by P2X7 receptors (purinergic ligand-gated cation channels) and an enhanced ability for these Ca2+ signals to reactivate ERK1/2 in the drug-tolerant state. Extracellular ATP, virtually ubiquitous in living systems, is the ligand that can initiate Ca2+ spikes via P2X7 channels. ATP is abundant in the tumor microenvironment and is released by dying cells, ironically implicating treatment-initiated cancer cell death as a source of trophic stimuli that leads to ERK reactivation and drug tolerance. Such a mechanism immediately offers an explanation of the inevitable relapse after BRAFi treatment in BRAF-mutant melanoma and points to actionable strategies to overcome it.

Tumor eradication by triplet therapy with BRAF inhibitor, TLR 7 agonist, and PD-1 antibody for BRAF-mutated melanoma.

Programmed death 1 (PD-1)/programmed death-ligand 1 inhibitors are commonly used to treat various cancers, including melanoma. However, their efficacy as monotherapy is limited, and combination immunotherapies are being explored to improve outcomes. In this study, we investigated a combination immunotherapy involving an anti-PD-1 antibody that blocks the major adaptive immune-resistant mechanisms, a BRAF inhibitor that inhibits melanoma cell proliferation, and multiple primary immune-resistant mechanisms, such as cancer cell-derived immunosuppressive cytokines, and a Toll-like receptor 7 agonist that enhances innate immune responses that promote antitumor T-cell induction and functions. Using a xenogeneic nude mouse model implanted with human BRAF-mutated melanoma, a BRAF inhibitor vemurafenib was found to restore T-cell-stimulatory activity in conventional dendritic cells by reducing immunosuppressive cytokines, including interleukin 6, produced by human melanoma. Additionally, intravenous administration of the Toll-like receptor 7 agonist DSR6434 enhanced tumor growth inhibition by vemurafenib through stimulating the plasmacytoid dendritic cells/interferon-α/natural killer cell pathways and augmenting the T-cell-stimulatory activity of conventional dendritic cells. In a syngeneic mouse model implanted with murine BRAF-mutated melanoma, the vemurafenib and DSR6434 combination synergistically augmented the induction of melanoma antigen gp100-specific T cells and inhibited tumor growth. Notably, only triplet therapy with vemurafenib, DSR6434, and the anti-PD-1 antibody resulted in complete regression of SIY antigen-transduced BRAF-mutated melanoma in a CD8 T-cell-dependent manner. These findings indicate that a triple-combination strategy targeting adaptive and primary resistant mechanisms while enhancing innate immune responses that promote tumor-specific T cells may be crucial for effective tumor eradication.