First line treatment of BRAF mutated advanced melanoma: Does one size fit all?

Cutaneous melanoma

Cutaneous melanoma is a common cancer in Australia and New Zealand, Europe, and North America, and its incidence is still increasing in many regions. Ultraviolet (UV) radiation exposure (for example, through excessive sunlight exposure) remains the primary risk factor for melanoma; however, public awareness campaigns have led to a marked reduction in mortality. In addition to genetic damage from UV radiation, specific genetic alterations have been linked to melanoma. The stage of the tumour at the time of diagnosis is of greater importance for melanoma prognosis than in almost any other cancer. Context-dependent genetic mutations that attenuate tumour-suppressive mechanisms or activate growth-promoting signalling pathways are crucial factors in the development of cutaneous melanoma. In addition to external factors such as UV radiation, the tumour microenvironment can contribute to melanoma progression, invasion and metastasis. Cutaneous melanoma treatment has improved considerably over the past decade with the discovery and development of immune checkpoint inhibitors and therapy targeting BRAF and MEK. Over the next decade, several priorities are likely to influence melanoma research and management, including the continued advance of precision medicine methods to identify the most suitable patients for the most effective treatment, with the aim of improving clinical outcomes.

Clinical Effectiveness and Cost-Effectiveness of Multigene Panel Sequencing in Advanced Melanoma: A Population-Level Real-World Target Trial Emulation

PURPOSE

Targeted therapy and immunotherapy promise improved survival in patients with advanced melanoma, yet the effectiveness and cost-effectiveness of multigene panel sequencing compared with single-gene BRAF testing to guide therapeutic decisions is unknown.

METHODS

Our population-based quasi-experimental retrospective target trial emulation used comprehensive patient-level data for 364 British Columbia, Canada, adults with an advanced melanoma diagnosis receiving multigene panel sequencing or single-gene BRAF testing between September 1, 2016, and December 31, 2018. We 1:1 matched multigene panel patients to controls using genetic algorithm-based matching. Outcomes included 3-year overall survival (OS) and health care costs (2021 Canadian dollars [CAD]) with incremental net monetary benefit for life-years gained (LYG). Outcomes were analyzed using inverse probability of censoring weighted linear regression for the intention-to-treat (ITT) effect. The per-protocol (PP) effect estimation also included stabilized inverse probability of treatment weights. We then used Weibull regression and Kaplan-Meier survival analysis.

RESULTS

We matched 147 multigene panel patients to controls, achieving balance for all covariates. After matching, ITT incremental costs were $19,447 CAD (95% CI, -$18,516 to $76,006) and incremental LYG were 0.22 (95% CI, -0.05 to 0.49). We found uncertainty in differences on OS using Kaplan-Meier (P = .11) and Weibull regression (hazard ratio [HR], 0.73 [95% CI, 0.51 to 1.03]) in the ITT. PP incremental costs were $36,367 CAD (95% CI, -$6,653 to $120,216]) and incremental LYG were 0.56 (95% CI, 0.39 to 1.24), with corresponding differences in OS using Kaplan-Meier (P = .02) and Weibull regression (HR, 0.56 [95% CI, 0.36 to 0.87]). The probability of multigene panels being cost-effective at $100,000/LYG CAD was 55% for ITT and 65% for PP.

CONCLUSION

The cost-effectiveness of multigene panels was evenly poised at higher thresholds, even when accounting for treatment initiation. Health systems reimbursing multigene panels and expensive therapies may be confronted with a value tradeoff, in which there may be improved survival albeit with a modest change in cost-effectiveness.

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.

Impact of Genomic Mutation on Melanoma Immune Microenvironment and IFN-1 Pathway-Driven Therapeutic Responses

The BRAFV600E mutation, found in approximately 50% of melanoma cases, plays a crucial role in the activation of the MAPK/ERK signaling pathway, which promotes tumor cell proliferation. This study aimed to evaluate its impact on the melanoma immune microenvironment and therapeutic responses, particularly focusing on immunogenic cell death (ICD), a pivotal cytotoxic process triggering anti-tumor immune responses. Through comprehensive in silico analysis of the Cancer Genome Atlas data, we explored the association between the BRAFV600E mutation, immune subtype dynamics, and tumor mutation burden (TMB). Our findings revealed that the mutation correlated with a lower TMB, indicating a reduced generation of immunogenic neoantigens. Investigation into immune subtypes reveals an exacerbation of immunosuppression mechanisms in BRAFV600E-mutated tumors. To assess the response to ICD inducers, including doxorubicin and Me-ALA-based photodynamic therapy (PDT), compared to the non-ICD inducer cisplatin, we used distinct melanoma cell lines with wild-type BRAF (SK-MEL-2) and BRAFV600E mutation (SK-MEL-28, A375). We demonstrated a differential response to PDT between the WT and BRAFV600E cell lines. Further transcriptomic analysis revealed upregulation of IFNAR1, IFNAR2, and CXCL10 genes associated with the BRAFV600E mutation, suggesting their involvement in ICD. Using a gene reporter assay, we showed that PDT robustly activated the IFN-1 pathway through cGAS-STING signaling. Collectively, our results underscore the complex interplay between the BRAFV600E mutation and immune responses, suggesting a putative correlation between tumors carrying the mutation and their responsiveness to therapies inducing the IFN-1 pathway, such as the ICD inducer PDT, possibly mediated by the elevated expression of IFNAR1/2 receptors.

Development of Personalized Strategies for Precisely Battling Malignant Melanoma

Melanoma is the most severe and fatal form of skin cancer, resulting from multiple gene mutations with high intra-tumor and inter-tumor molecular heterogeneity. Treatment options for patients whose disease has progressed beyond the ability for surgical resection rely on currently accepted standard therapies, notably immune checkpoint inhibitors and targeted therapies. Acquired resistance to these therapies and treatment-associated toxicity necessitate exploring novel strategies, especially those that can be personalized for specific patients and/or populations. Here, we review the current landscape and progress of standard therapies and explore what personalized oncology techniques may entail in the scope of melanoma. Our purpose is to provide an up-to-date summary of the tools at our disposal that work to circumvent the common barriers faced when battling melanoma.

Moving from conventional to adaptive risk stratification for oropharyngeal cancer

Oropharyngeal cancer (OPC) poses a complex therapeutic dilemma for patients and oncologists alike, made worse by the epidemic increase in new cases associated with the oncogenic human papillomavirus (HPV). In a counterintuitive manner, the very thing which gives patients hope, the high response rate of HPV-associated OPC to conventional chemo-radiation strategies, has become one of the biggest challenges for the field as a whole. It has now become clear that for ~30-40% of patients, treatment intensity could be reduced without losing therapeutic efficacy, yet substantially diminishing the acute and lifelong morbidity resulting from conventional chemotherapy and radiation. At the same time, conventional approaches to de-escalation at a population (selected or unselected) level are hampered by a simple fact: we lack patient-specific information from individual tumors that can predict responsiveness. This results in a problematic tradeoff between the deleterious impact of de-escalation on patients with aggressive, treatment-refractory disease and the beneficial reduction in treatment-related morbidity for patients with treatment-responsive disease. True precision oncology approaches require a constant, iterative interrogation of solid tumors prior to and especially during cancer treatment in order to tailor treatment intensity to tumor biology. Whereas this approach can be deployed in hematologic diseases with some success, our ability to extend it to solid cancers with regional metastasis has been extremely limited in the curative intent setting. New developments in metabolic imaging and quantitative interrogation of circulating DNA, tumor exosomes and whole circulating tumor cells, however, provide renewed opportunities to adapt and individualize even conventional chemo-radiation strategies to diseases with highly variable biology such as OPC. In this review, we discuss opportunities to deploy developing technologies in the context of institutional and cooperative group clinical trials over the coming decade.

Unique vulnerability of RAC1-mutant melanoma to combined inhibition of CDK9 and immune checkpoints

RAC1P29S is the third most prevalent hotspot mutation in sun-exposed melanoma. RAC1 alterations in cancer are correlated with poor prognosis, resistance to standard chemotherapy, and insensitivity to targeted inhibitors. Although RAC1P29S mutations in melanoma and RAC1 alterations in several other cancers are increasingly evident, the RAC1-driven biological mechanisms contributing to tumorigenesis remain unclear. Lack of rigorous signaling analysis has prevented identification of alternative therapeutic targets for RAC1P29S-harboring melanomas. To investigate the RAC1P29S-driven effect on downstream molecular signaling pathways, we generated an inducible RAC1P29S expression melanocytic cell line and performed RNA-sequencing (RNA-seq) coupled with multiplexed kinase inhibitor beads and mass spectrometry (MIBs/MS) to establish enriched pathways from the genomic to proteomic level. Our proteogenomic analysis identified CDK9 as a potential new and specific target in RAC1P29S-mutant melanoma cells. In vitro, CDK9 inhibition impeded the proliferation of in RAC1P29S-mutant melanoma cells and increased surface expression of PD-L1 and MHC Class I proteins. In vivo, combining CDK9 inhibition with anti-PD-1 immune checkpoint blockade significantly inhibited tumor growth only in melanomas that expressed the RAC1P29S mutation. Collectively, these results establish CDK9 as a novel target in RAC1-driven melanoma that can further sensitize the tumor to anti-PD-1 immunotherapy.

Improving care of melanoma patients through efficient, integrated cellular-molecular pathology workflows using tissue samples with low tumour nuclear content

AIMS

The aim of this quality improvement project was to improve the turnaround time of B-raf proto-oncogene (BRAF) mutation testing in patients with malignant melanoma to support oncologists in making timely treatment decisions.

METHODS

This is a prospective in-house verification of the Idylla BRAF test as compared with DNA panel next-generation sequencing (NGS) performed at an external laboratory.

RESULTS

The Idylla BRAF test had an overall concordance of 95% compared with NGS. This was considered sufficiently good for use in patients with a poor performance status who were at risk of rapid clinical deterioration. Reliable results can be generated using the Idylla BRAF test in tissue sections with tumour neoplastic cell content below 50%. We present a multidisciplinary clinical care algorithm to support dual testing.

CONCLUSIONS

The Idylla BRAF test has the potential to make a significant positive impact on progression-free survival of malignant melanoma patients due to its rapid turnaround time. The Idylla BRAF test can be used as an adjunct to NGS for timely management of patients, particularly those with a poor performance status at presentation.

Real-World Evaluation of the Management, Treatment Pathways and Outcome of Melanoma Patients with Target Therapies in Italy

INTRODUCTION

In recent years, an increasing trend in the incidence of melanoma has been observed in Europe. Although early diagnosis and prompt intervention with local resection often results in positive outcomes, conversely, metastatic disease is still clinically challenging with a poor prognosis and a 5-year survival of around 30%. The growing awareness of melanoma biology and of antitumor immune responses has allowed the development of novel therapies targeted at specific molecular alterations occurring at advanced stages. This real-world analysis examined patients with melanoma in Italy, focusing on treatment patterns, outcome, time to discontinuation (TTD), and resource consumption.

METHODS

Two retrospective observational analyses were conducted for BRAF+ patients with metastatic melanoma and those with a positive sentinel lymph node biopsy in an adjuvant setting, retrieving data from the administrative databases covering 13.3 million residents. The cohort melanoma BRAF+ in metastatic setting comprised 729 patients with targeted therapy (TT) (n = 671 with TT as first line and 79 as second line).

RESULTS

Median TTD was 10.6 months in first line and 8.1 months in second line. Median overall survival from the start of first TT line was 27 months and was 11.8 months for patients with brain metastasis. In the dabrafenib plus trametinib patients, main healthcare resource consumption tended to increase in the presence of brain metastasis. The cohort with a positive sentinel lymph node biopsy under adjuvant therapy (n = 289) included 8% patients treated with dabrafenib plus trametinib or tested BRAF+, 5% BRAF wild-type, and 10% under immunotherapy.

CONCLUSION

Our findings provided an overview on TT utilization on metastatic melanoma patients in real clinical practice and highlighted an increased burden in brain metastatic patients.

Unique vulnerability of RAC1-mutant melanoma to combined inhibition of CDK9 and immune checkpoints

RAC1P29S is the third most prevalent hotspot mutation in sun-exposed melanoma. RAC1 alterations in cancer are correlated with poor prognosis, resistance to standard chemotherapy, and insensitivity to targeted inhibitors. Although RAC1P29S mutations in melanoma and RAC1 alterations in several other cancers are increasingly evident, the RAC1-driven biological mechanisms contributing to tumorigenesis remain unclear. Lack of rigorous signaling analysis has prevented identification of alternative therapeutic targets for RAC1P29S-harboring melanomas. To investigate the RAC1P29S-driven effect on downstream molecular signaling pathways, we generated an inducible RAC1P29S expression melanocytic cell line and performed RNA-sequencing (RNA-seq) coupled with multiplexed kinase inhibitor beads and mass spectrometry (MIBs/MS) to establish enriched pathways from the genomic to proteomic level. Our proteogenomic analysis identified CDK9 as a potential new and specific target in RAC1P29S-mutant melanoma cells. In vitro, CDK9 inhibition impeded the proliferation of in RAC1P29S-mutant melanoma cells and increased surface expression of PD-L1 and MHC Class I proteins. In vivo, combining CDK9 inhibition with anti-PD-1 immune checkpoint blockade significantly inhibited tumor growth only in melanomas that expressed the RAC1P29S mutation. Collectively, these results establish CDK9 as a novel target in RAC1-driven melanoma that can further sensitize the tumor to anti-PD-1 immunotherapy.

New Phenylspirodrimanes from the Sponge-Associated Fungus Stachybotrys chartarum MUT 3308

Two phenylspirodrimanes, never isolated before, stachybotrin J (1) and new stachybocin G (epi-stachybocin A) (2), along with the already reported stachybotrin I (3), stachybotrin H (4), stachybotrylactam (5), stachybotrylactam acetate (6), 2α-acetoxystachybotrylactam acetate (7), stachybotramide (8), chartarlactam B (9), and F1839-J (10) were isolated from the sponge-associated fungus Stachybotrys chartarum MUT 3308. Their structures were established based on extensive spectrometric (HRMS) and spectroscopic (1D and 2D NMR) analyses. Absolute configurations of the stereogenic centers of stachybotrin J (1), stachybocin G (2), and stachybotrin I (3), were determined by comparison of their experimental circular dichroism (CD) spectra with their time-dependent density functional theory (TD-DFT) circular dichroism (ECD) spectra. The putative structures of seventeen additional phenylspirodrimanes were proposed by analysis of their respective MS/MS spectra through a Feature-Based Molecular Networking approach. All the isolated compounds were evaluated for their cytotoxicity against five aggressive cancer cell lines (MP41, 786, 786R, CAL33, and CAL33RR), notably including two resistant human cancer cell lines (786R, CAL33RR), and compounds 5, 6, and 7 exhibited cytotoxicity with IC50 values in the range of 0.3−2.2 µM.

Small molecule inhibitors targeting the cancers

Compared with traditional therapies, targeted therapy has merits in selectivity, efficacy, and tolerability. Small molecule inhibitors are one of the primary targeted therapies for cancer. Due to their advantages in a wide range of targets, convenient medication, and the ability to penetrate into the central nervous system, many efforts have been devoted to developing more small molecule inhibitors. To date, 88 small molecule inhibitors have been approved by the United States Food and Drug Administration to treat cancers. Despite remarkable progress, small molecule inhibitors in cancer treatment still face many obstacles, such as low response rate, short duration of response, toxicity, biomarkers, and resistance. To better promote the development of small molecule inhibitors targeting cancers, we comprehensively reviewed small molecule inhibitors involved in all the approved agents and pivotal drug candidates in clinical trials arranged by the signaling pathways and the classification of small molecule inhibitors. We discussed lessons learned from the development of these agents, the proper strategies to overcome resistance arising from different mechanisms, and combination therapies concerned with small molecule inhibitors. Through our review, we hoped to provide insights and perspectives for the research and development of small molecule inhibitors in cancer treatment.

Targeting Mutant p53 for Cancer Treatment: Moving Closer to Clinical Use?

Simple Summary

Cancer is largely caused by genetic alterations such as mutations in a group of genes known as cancer driver genes. Many of the key advances in cancer treatment in recent years have involved blocking these driver genes using a new generation of anti-cancer drugs. Although p53 is the most frequently mutated gene in human cancers, historically, it has proved difficult to develop drugs against it. However, recently, several new drugs have become available for neutralizing the cancer-promoting effects of mutant p53. The aim of this article is to discuss the most promising of these drugs, especially those that are being investigated in clinical trials.

Abstract

Mutant p53 is one of the most attractive targets for new anti-cancer drugs. Although traditionally regarded as difficult to drug, several new strategies have recently become available for targeting the mutant protein. One of the most promising of these involves the use of low molecular weight compounds that promote refolding and reactivation of mutant p53 to its wild-type form. Several such reactivating drugs are currently undergoing evaluation in clinical trials, including eprenetapopt (APR-246), COTI-2, arsenic trioxide and PC14586. Of these, the most clinically advanced for targeting mutant p53 is eprenetapopt which has completed phase I, II and III clinical trials, the latter in patients with mutant TP53 myelodysplastic syndrome. Although no data on clinical efficacy are currently available for eprenetapopt, preliminary results suggest that the drug is relatively well tolerated. Other strategies for targeting mutant p53 that have progressed to clinical trials involve the use of drugs promoting degradation of the mutant protein and exploiting the mutant protein for the development of anti-cancer vaccines. With all of these ongoing trials, we should soon know if targeting mutant p53 can be used for cancer treatment. If any of these trials show clinical efficacy, it may be a transformative development for the treatment of patients with cancer since mutant p53 is so prevalent in this disease.

First-line pembrolizumab versus dabrafenib/trametinib treatment for BRAF V600-mutant advanced melanoma

BACKGROUND

Limited data are available to assist the selection between immune checkpoint inhibitors and BRAF/mitogen-activated protein kinase kinase inhibitors as first-line treatment for patients with BRAF-mutant advanced malignant melanoma.

OBJECTIVE

To investigate the outcomes associated with first-line pembrolizumab or dabrafenib/trametinib treatment for advanced melanoma with activating BRAF V600 mutation.

METHODS

Data of patients with BRAF V600-mutant melanoma who were treated with first-line pembrolizumab (n = 40) or dabrafenib/trametinib (n = 32) were analyzed. Tumor response, progression-free survival, and overall survival were evaluated. Immune evasion accompanied with emerging resistance to BRAF/mitogen-activated protein kinase kinase inhibitors was assessed.

RESULTS

A longer overall survival was observed after first-line pembrolizumab treatment than after first-line dabrafenib/trametinib treatment (hazard ratio = 2.910, 95% CI: 1.552-5.459), although there were no significant differences in progression-free survival (P = .375) and response rate (P = .123). Emergence of resistance to dabrafenib/trametinib co-occurred with immune evasion, enabling melanoma cells to escape recognition and killing by Melan-A-specific CD8⁺ T cells.

LIMITATIONS

Analysis was conducted in a retrospective manner.

CONCLUSION

Pembrolizumab may be recommended over BRAF/mitogen-activated protein kinase kinase inhibitors as the first-line treatment in patients with advanced BRAF V600-mutant melanoma.

Oropharyngeal cancer outcomes correlate with p16 status, multinucleation and immune infiltration

Oropharyngeal squamous cell carcinoma (OPSCC), largely fueled by the human papillomavirus (HPV), has a complex biological and immunologic phenotype. Although HPV/p16 status can be used to stratify OPSCC patients as a function of survival, it remains unclear what drives an improved treatment response in HPV-associated OPSCC and whether targetable biomarkers exist that can inform a precision oncology approach. We analyzed OPSCC patients treated between 2000 and 2016 and correlated locoregional control (LRC), disease-free survival (DFS) and overall survival (OS) with conventional clinical parameters, risk parameters generated using deep-learning algorithms trained to quantify tumor-infiltrating lymphocytes (TILs) (OP-TIL) and multinucleated tumor cells (MuNI) and targeted transcriptomics. P16 was a dominant determinant of LRC, DFS and OS, but tobacco exposure, OP-TIL and MuNI risk features correlated with clinical outcomes independent of p16 status and the combination of p16, OP-TIL and MuNI generated a better stratification of OPSCC risk compared to individual parameters. Differential gene expression (DEG) analysis demonstrated overlap between MuNI and OP-TIL and identified genes involved in DNA repair, oxidative stress response and tumor immunity as the most prominent correlates with survival. Alteration of inflammatory/immune pathways correlated strongly with all risk features and oncologic outcomes. This suggests that development of OPSCC consists of an intersection between multiple required and permissive oncogenic and immunologic events which may be mechanistically linked. The strong relationship between tumor immunity and oncologic outcomes in OPSCC regardless of HPV status may provide opportunities for further biomarker development and precision oncology approaches incorporating immune checkpoint inhibitors for maximal anti-tumor efficacy.

Long Term Results and Prognostic Biomarkers for Anti-PD1 Immunotherapy Used after BRAFi/MEKi Combination in Advanced Cutaneous Melanoma Patients

(1) Background: BRAFi/MEKi are usually offered as a first line treatment for patients requiring rapid response; with elevated lactate dehydrogenase (LDH) activity, large tumor burden, and with brain metastases. The efficacy of second line therapies after BRAFi/MEKI failure is now well defined. (2) Methods: Patients treated with first line target BRAFi/MEKi therapy (vemurafenib plus cobimetinib, dabrafenib plus trametinib or encorafenib plus binimetinib); and for the second line treatment immunotherapy with programmed cell death 1 (PD-1) checkpoint inhibitors (nivolumab or pembrolizumab) with at least one cycle of second line were analyzed for survival and prognostic biomarkers. (3) Results: There were no statistically significant differences in ORR between the treatment groups with nivolumab and pembrolizumab, as well as median progression free-survival (PSF) and overall survival (OS) since the initiation of second line therapy; on nivolumab OS was 6.6 months, and on pembrolizumab 5.0 months. The greatest clinical benefit with second line immunotherapy was observed in patients with LDH ≤ ULN and <3 organ sites with metastasis at baseline. Longer OS was also noted in patients with time to PD  >6 months in first line (slow progression). (4) Conclusions: Second line anti-PD1 immunotherapy is effective in BRAF-mutated melanoma patients after BRAFi/MEKi therapy failure.

Intermittent treatment of BRAFV600E melanoma cells delays resistance by adaptive resensitization to drug rechallenge

Preclinical studies of metastatic melanoma treated with targeted therapeutics have suggested that alternating periods of treatment and withdrawal might delay the onset of resistance. This has been attributed to drug addiction, where cells lose fitness upon drug removal due to the resulting hyperactivation of mitogen-activated protein (MAP) kinase signaling. This study presents evidence that the intermittent treatment response can also be explained by the resensitization of cells following drug removal and enhanced cell loss upon drug rechallenge. Resensitization is accompanied by adaptive transcriptomic switching and occurs despite the sustained expression of resistance genes throughout the intermittent treatment.

Patients with melanoma receiving drugs targeting BRAF^V600E and mitogen-activated protein (MAP) kinase kinases 1 and 2 (MEK1/2) invariably develop resistance and face continued progression. Based on preclinical studies, intermittent treatment involving alternating periods of drug withdrawal and rechallenge has been proposed as a method to delay the onset of resistance. The beneficial effect of intermittent treatment has been attributed to drug addiction, where drug withdrawal reduces the viability of resistant cells due to MAP kinase pathway hyperactivation. However, the mechanistic basis of the intermittent effect is incompletely understood. We show that intermittent treatment with the BRAF^V600E inhibitor, LGX818/encorafenib, suppresses growth compared with continuous treatment in human melanoma cells engineered to express BRAF^V600E, p61-BRAF^V600E, or MEK2^C125 oncogenes. Analysis of the BRAF^V600E-overexpressing cells shows that, while drug addiction clearly occurs, it fails to account for the advantageous effect of intermittent treatment. Instead, growth suppression is best explained by resensitization during periods of drug removal, followed by cell death after drug readdition. Continuous treatment leads to transcriptional responses prominently associated with chemoresistance in melanoma. By contrast, cells treated intermittently reveal a subset of transcripts that reverse expression between successive cycles of drug removal and rechallenge and include mediators of cell invasiveness and the epithelial-to-mesenchymal transition. These transcripts change during periods of drug removal by adaptive switching, rather than selection pressure. Resensitization occurs against a background of sustained expression of melanoma resistance genes, producing a transcriptome distinct from that of the initial drug-naive cell state. We conclude that phenotypic plasticity leading to drug resensitization can underlie the beneficial effect of intermittent treatment.

JAK2 inhibitor persistence in MPN: uncovering a central role of ERK activation

The Philadelphia chromosome negative myeloproliferative neoplasms, including polycythemia vera, essential thrombocytosis, and myelofibrosis, are driven by hyper activation of the JAK2 tyrosine kinase, the result of mutations in three MPN driving genes: JAK2, MPL, and CALR. While the anti-inflammatory effects of JAK2 inhibitors can provide improved quality of life for many MPN patients, the upfront and persistent survival of disease-driving cells in MPN patients undergoing JAK2 inhibitor therapy thwarts potential for remission. Early studies indicated JAK2 inhibitor therapy induces heterodimeric complex formation of JAK2 with other JAK family members leading to sustained JAK2-dependent signaling. Recent work has described novel cell intrinsic details as well as cell extrinsic mechanisms that may contribute to why JAK2 inhibition may be ineffective at targeting MPN driving cells. Diverse experimental strategies aimed at uncovering mechanistic details that contribute to JAK2 inhibitor persistence have each highlighted the role of MEK/ERK activation. These approaches include, among others, phosphoproteomic analyses of JAK2 signaling as well as detailed assessment of JAK2 inhibition in mouse models of MPN. In this focused review, we highlight these and other studies that collectively suggest targeting MEK/ERK in combination with JAK2 inhibition has the potential to improve the efficacy of JAK2 inhibitors in MPN patients. As MPN patients patiently wait for improved therapies, such studies should further strengthen optimism that pre-clinical research is continuing to uncover mechanistic insights regarding the ineffectiveness of JAK2 inhibitors, which may lead to development of improved therapeutic strategies.

Cancer Therapy Guided by Mutation Tests: Current Status and Perspectives

The administration of many cancer drugs is tailored to genetic tests. Some genomic events, e.g., alterations of EGFR or BRAF oncogenes, result in the conformational change of the corresponding proteins and call for the use of mutation-specific compounds. Other genetic perturbations, e.g., HER2 amplifications, ALK translocations or MET exon 14 skipping mutations, cause overproduction of the entire protein or its kinase domain. There are multilocus assays that provide integrative characteristics of the tumor genome, such as the analysis of tumor mutation burden or deficiency of DNA repair. Treatment planning for non-small cell lung cancer requires testing for EGFR, ALK, ROS1, BRAF, MET, RET and KRAS gene alterations. Colorectal cancer patients need to undergo KRAS, NRAS, BRAF, HER2 and microsatellite instability analysis. The genomic examination of breast cancer includes testing for HER2 amplification and PIK3CA activation. Melanomas are currently subjected to BRAF and, in some instances, KIT genetic analysis. Predictive DNA assays have also been developed for thyroid cancers, cholangiocarcinomas and urinary bladder tumors. There is an increasing utilization of agnostic testing which involves the analysis of all potentially actionable genes across all tumor types. The invention of genomically tailored treatment has resulted in a spectacular improvement in disease outcomes for a significant portion of cancer patients.

Circular RNA ZNF609 drives tumor progression by regulating the miR-138-5p/SIRT7 axis in melanoma

Melanoma serves as a prevailing and lethal skin malignancy with high mortality and a growing number of patients globally. Circular RNAs (circRNAs), as a type of emerging cellular regulator, are involved in the modulation of melanoma. Nevertheless, the function of circZNF609 in melanoma development remains obscure. In this study, we were interested in the effect and the underlying mechanism of circZNF609 on DNA damage during melanoma progression. The circZNF609 depletion significantly suppressed melanoma cell invasion, migration, and proliferation, and stimulated apoptosis. Meanwhile, comet assays showed that the tail length and γH2AX levels were elevated by circZNF609 depletion. Mechanically, circZNF609 sponged miR-138-5p and miR-138-5p targeted SIRT7 in the melanoma cells. The SIRT7 overexpression and miR-138-5p inhibitor could reverse circZNF609 depletion-mediated DNA damage and malignant progression in melanoma cells. Functionally, CircZNF609 promoted cell growth of melanoma in the nude mice. Consequently, we conclude that circZNF609 suppresses DNA damage and potentially enhances melanoma progression at the experimental condition by modulating the miR-138-5p/SIRT7 axis. Our finding provides new insights into the mechanism by which circZNF609 modulates the development of melanoma. CircZNF609 and miR-138-5p may be utilized as therapeutic targets for melanoma.

A Novel Regimen for Treating Melanoma: MCL1 Inhibitors and Azacitidine

Although treatment options for melanoma patients have expanded in recent years with the approval of immunotherapy and targeted therapy, there is still an unmet need for new treatment options for patients that are ineligible for, or resistant to these therapies. BH3 mimetics, drugs that mimic the activity of pro-apoptotic BCL2 family proteins, have recently achieved remarkable success in the clinical setting. The combination of BH3 mimetic ABT-199 (venetoclax) plus azacitidine has shown substantial benefit in treating acute myelogenous leukemia. We evaluated the efficacy of various combinations of BH3 mimetic + azacitidine in fourteen human melanoma cell lines from cutaneous, mucosal, acral and uveal subtypes. Using a combination of cell viability assay, BCL2 family knockdown cell lines, live cell imaging, and sphere formation assay, we found that combining inhibition of MCL1, an anti-apoptotic BCL2 protein, with azacitidine had substantial pro-apoptotic effects in multiple melanoma cell lines. Specifically, this combination reduced cell viability, proliferation, sphere formation, and induced apoptosis. In addition, this combination is highly effective at reducing cell viability in rare mucosal and uveal subtypes. Overall, our data suggest this combination as a promising therapeutic option for some patients with melanoma and should be further explored in clinical trials.