Dabrafenib and trametinib versus dabrafenib and placebo for Val600 BRAF-mutant melanoma: a multicentre, double-blind, phase 3 randomised controlled trial

Challenges in Conducting Clinical Research on Patients With Advanced Melanoma

Unprecedented advances in the treatment of melanoma and the large number of investigational therapies entering clinical studies not only represent outstanding achievements, but also create major challenges for clinical research in melanoma. The challenges for accrual and for developing important new data in trials include the relatively low incidence of melanoma compared with other diseases, a shrinking pool of patients for trials because of the high efficacy of standard of care therapy, requirements for larger studies and longer duration of follow-up to detect signals of activity or establish efficacy, and suboptimal predictive biomarkers for the vast number of new combinations and new agents. The cost of new treatments remains a major concern, particularly because current standard of care involves doublets of targeted therapy or immune therapy, and clinically meaningful further increases in efficacy may require development of triplets or larger multidrug combinations. Toxicities of the current doublets, particularly for immune therapy, may limit development of some multidrug regimens or may require novel solutions such as sequencing or alternating schedules. The activity of first-line therapies may push development of new drugs or combinations into the second-line setting or into subgroups with suboptimal response to the first-line doublets as identified by predictive clinical variables or tissue biomarkers.

Targeted Therapies in Combination With Immune Therapies for the Treatment of Metastatic Melanoma

In recent years, the field of oncology has witnessed many breakthroughs in the treatment of advanced malignancies, particularly in patients with advanced melanoma. Targeted and immune checkpoint therapies have emerged as the primary treatment strategies for these patients. Molecular profiling of melanoma is incorporated into routine practice to identify potential therapeutic targets, and patients are offered either a targeted or immune checkpoint inhibitor therapy approach. Both strategies have limitations where not all patients experience durable responses. Preclinical data have demonstrated the ability of targeted therapy to enhance activity of effector T cells, reduce immunosuppressive cytokine production, and increase tumor cell antigen presentation, which can augment antitumor immunity. In vivo models have shown synergy with improved tumor control when targeted and immune checkpoint agents are combined. Therefore, combination strategies with targeted and immune checkpoint therapy may improve patient outcomes. Early clinical data with anti-programmed cell-death protein 1/programmed cell-death ligand 1 agents in combination with targeted inhibitors appear to have acceptable toxicity rates and the potential for enhanced antitumor activity. This review explores the current status of preclinical and clinical development for these combination approaches in patients with advanced melanoma.

Novel Targeted Therapies for Metastatic Melanoma

Oncogene-targeted therapy is a major component of precision oncology, and although patients with metastatic melanoma have experienced improved outcomes with this strategy, there are a number of potential therapeutic targets currently under study that may further increase the drug armamentarium for this patient population. In this review, we discuss the landscape of targeted therapies for patients with advanced melanoma, focusing on oncogene mutation-specific targets. In patients with typical BRAF V600-mutant melanoma, combination BRAF and MEK inhibition has surpassed outcomes compared with monotherapy with BRAF or MEK inhibition alone, and current strategies seek to address inevitable resistance mechanisms. For patients with NRAS-mutant melanoma, MEK inhibitor monotherapy and combined MEK and CDK4/6 inhibition are burgeoning strategies; for patients with KIT-mutant melanoma, tyrosine kinase inhibition is being leveraged, and for NF-1-mutant melanoma, mTOR and MEK inhibition is being actively evaluated. In patients with atypical, non-V600 BRAF-mutant melanoma, MEK inhibitor monotherapy is the potential novel targeted approach on the horizon. For advanced uveal melanoma, novel targets such as IMCgp100 and glembatumumab have shown activity in early studies. We review additional strategies that remain in the preclinical and early clinical pipeline, so there is much hope for the future of targeted agents for distinct molecular cohorts of patients with advanced melanoma.

Multiple treatment comparison of seven new drugs for patients with advanced malignant melanoma: a systematic review and health economic decision model in a Norwegian setting

OBJECTIVE

To assess the relative effectiveness and cost-effectiveness of seven new drugs (cobimetinib, dabrafenib, ipilimumab, nivolumab, pembrolizumab, trametinib and vemurafenib) used for treatment of patients with advanced malignant melanoma in the Norwegian setting.

DESIGN

A multiple technology assessment.

PATIENTS

Patients with advanced malignant melanoma aged 18 or older.

DATA SOURCES

A systematic search for randomised controlled trials in relevant bibliographic databases.

METHODS

We performed network meta-analyses using both direct and indirect evidence with dacarbazine as a common comparator. We ranked the different treatments in terms of their likelihood of leading to the best results for each endpoint. The cost-utility analysis was based on a probabilistic discrete-time Markov cohort model. The model calculated the costs and quality-adjusted life years (QALYs) with different treatment strategies from a healthcare perspective. Sensitivity analysis was performed by means of Monte Carlo simulation.

RESULTS

Monotherapies with a programmed cell death 1 (PD-1) immune-checkpoint-inhibitor had a higher probability of good performance for overall survival than monotherapies with ipilimumab or BRAF/MEK inhibitors. The combination treatments had all similar levels of effectiveness to the PD-1 immune-checkpoint-inhibitors.PD-1 immune-checkpoint-inhibitors are more effective and more costly compared with ipilimumab in monotherapy. Nivolumab in combination with ipilimumab had higher costs and the same level of effectiveness as the PD-1 immune-checkpoint-inhibitors in monotherapy.BRAF/MEK inhibitor combinations (dabrafenib and trametinib or vemurafenib and cobimetinib) had both similar effectiveness and cost-effectiveness; however, the combination therapies are more likely to give higher quality adjusted life year gains than BRAF or MEK inhibitor monotherapies, but to a higher cost.

CONCLUSIONS

None of the drugs investigated can be considered cost-effective at what has normally been considered a reasonable willingness-to-pay (WTP) in Norway. Price reductions (from the official list prices) in the region of 63%-84% would be necessary for these drugs to be cost-effective at a WTP of €55 850 per QALY.

Somatic driver mutations in melanoma

Melanoma has one of the highest somatic mutational burdens among solid malignancies. Although the rapid progress in genomic research has contributed immensely to our understanding of the pathogenesis of melanoma, the clinical significance of the vast array of genomic alterations discovered by next-generation sequencing is far from being fully characterized. Most mutations prevalent in melanoma are simply neutral "passengers," which accompany functionally significant "drivers" under transforming conditions. The delineation of driver mutations from passenger mutations is critical to the development of targeted therapies. Novel advances in genomic data analysis have aided in distinguishing true driver mutations involved in tumor progression. Here, the authors review the current literature on important somatic driver mutations in melanoma, along with the implications for treatment. Cancer 2017;123:2104-17. © 2017 American Cancer Society.

Interaction of molecular alterations with immune response in melanoma

Major advances have been made in melanoma treatment with the use of molecularly targeted therapies and immunotherapies, and numerous regimens are now approved by the US Food and Drug Administration for patients with stage IV disease. However, therapeutic resistance remains an issue to both classes of agents, and reliable biomarkers of therapeutic response and resistance are lacking. Mechanistic insights are being gained through preclinical studies and translational research, offering potential strategies to enhance responses and survival in treated patients. A comprehensive understanding of the immune effects of common mutations at play in melanoma is critical, as is an appreciation of the molecular mechanisms contributing to therapeutic resistance to immunotherapy. These mechanisms and the interplay between them are discussed herein. Cancer 2017;123:2130-42. © 2017 American Cancer Society.

Molecular insights into melanoma brain metastases

Substantial proportions of patients with metastatic melanoma develop brain metastases during the course of their disease, often resulting in significant morbidity and death. Despite recent advances with BRAF/MEK and immune-checkpoint inhibitors in the treatment of patients who have melanoma with extracerebral metastases, patients who have melanoma brain metastases still have poor overall survival, highlighting the need for further therapy options. A deeper understanding of the molecular pathways involved in the development of melanoma brain metastases is required to develop more brain-specific therapies. Here, the authors summarize the currently known preclinical data and describe steps involved in the development of melanoma brain metastases. Only by knowing the molecular background is it possible to design new therapeutic agents that can be used to improve the outcome of patients with melanoma brain metastases. Cancer 2017;123:2163-75. © 2017 American Cancer Society.

Optimal Use of BRAF Targeting Therapy in the Immunotherapy Era

PURPOSE OF REVIEW

The therapeutic landscape for metastatic melanoma has been revolutionized in recent years. This review will discuss existing evidence for therapeutic approaches for BRAF-mutated metastatic melanoma.

RECENT FINDINGS

Clinical trials involving combined BRAF/MEK inhibition with either vemurafenib plus cobimetinib or dabrafenib plus trametinib have shown improved overall survival compared to monotherapy with BRAF inhibitors alone. In a subset of patients with good prognostic factors, long-term clinical benefit has been noted. Simultaneously, developments in immunotherapy have suggested long-lasting survival for some patients. In advanced BRAF-mutated melanoma, both BRAF/MEK inhibition and immunotherapy agents show improved overall survival and, in a small population of patients, prolonged and long-term benefit as compared to standard chemotherapy. Trials are currently underway evaluating sequencing of these therapies and the safety of targeted therapy plus immunotherapy combinations.

Distant intracranial failure in melanoma brain metastases treated with stereotactic radiosurgery in the era of immunotherapy and targeted agents

Purpose

Stereotactic radiosurgery (SRS) in combination with immunotherapy (IMT) or targeted therapy is increasingly being used in the setting of melanoma brain metastases (MBMs). The synergistic properties of combination therapy are not well understood. We compared the distant intracranial failure rates of intact MBMs treated with SRS, SRS + IMT, and SRS + targeted therapy.

Methods and materials

Combination therapy was defined as delivery of SRS within 3 months of IMT (anti-CTLA-4 /anti-PD-1 therapy) or targeted therapy (BRAF/MEK inhibitors). The primary endpoint was distant intracranial failure after SRS, which was defined as any new MBM identified on brain magnetic resonance imaging. Outcomes were evaluated using the Kaplan Meier method and Cox proportional hazards.

Results

A total of 72 patients with melanoma with 233 MBMs were treated between April 2006 and April 2016. The number of MBMs within each treatment group was as follows: SRS: 121; SRS + IMT: 48; and SRS + targeted therapy: 64. The median follow-up was 8.9 months. One-year distant intracranial control rates for SRS, SRS + IMT, and SRS + targeted therapy were 11.5%, 60%, and 10%, respectively (P < .001). On multivariate analysis, after adjusting for steroid use and number of MBMs, SRS + IMT remained associated with a significant reduction in distant intracranial failure compared with SRS (hazard ratio [HR], 0.48; 95% confidence interval [CI], 0.29-0.80; P = .003) and compared with SRS + targeted therapy (HR, 0.41; 95% CI, 0.25-0.68; P = .001).One-year local control for SRS, SRS + IMT, and SRS + targeted therapy was 66%, 85%, and 72%, respectively (P = .044). On multivariate analysis, after adjusting for dose, SRS + IMT remained associated with a significant reduction in local failure compared with SRS alone (HR, 0.37; 95% CI, 0.14-0.95; P = .04).

Conclusions

SRS with immunotherapy is associated with decreased distant and local intracranial failure compared with SRS alone. Prospective studies are warranted to validate this result.

Trametinib Drives T-cell-Dependent Control of KRAS-Mutated Tumors by Inhibiting Pathological Myelopoiesis

Targeted therapies elicit seemingly paradoxical and poorly understood effects on tumor immunity. Here, we show that the MEK inhibitor trametinib abrogates cytokine-driven expansion of monocytic myeloid-derived suppressor cells (mMDSC) from human or mouse myeloid progenitors. MEK inhibition also reduced the production of the mMDSC chemotactic factor osteopontin by tumor cells. Together, these effects reduced mMDSC accumulation in tumor-bearing hosts, limiting the outgrowth of KRas-driven breast tumors, even though trametinib largely failed to directly inhibit tumor cell proliferation. Accordingly, trametinib impeded tumor progression in vivo through a mechanism requiring CD8⁺ T cells, which was paradoxical given the drug's reported ability to inhibit effector lymphocytes. Confirming our observations, adoptive transfer of tumor-derived mMDSC reversed the ability of trametinib to control tumor growth. Overall, our work showed how the effects of trametinib on immune cells could partly explain its effectiveness, distinct from its activity on tumor cells themselves. More broadly, by providing a more incisive view into how MEK inhibitors may act against tumors, our findings expand their potential uses to generally block mMDSC expansion, which occurs widely in cancers to drive their growth and progression. Cancer Res; 76(21); 6253-65. ©2016 AACR.

BRAF-Mutated Colorectal Cancer: What Is the Optimal Strategy for Treatment?

OPINION STATEMENT

The BRAF activating mutation, harbored by approximately 10% of colorectal cancers (CRC), confers dramatic prognosis to advanced diseases. In early-stage setting, the identification of the BRAF mutation does not impact the therapeutic decision. Yet, the BRAF mutation could be considered as a stratification factor in adjuvant trials, because of its prognostic impact after relapse. Moreover, both BRAF mutation and mismatch repair (MMR) statuses should be determined in all CRC to help identify sporadic tumors versus Lynch syndrome-related tumors. Indeed, in patients with MMR-deficient (dMMR) tumors and MLH1 loss of expression, the BRAFV600E mutation indicates a sporadic origin. In advanced BRAF-mutated CRC, the standard of care remains fluoropyrimidine-based cytotoxic regimen in combination with bevacizumab. Although a recent meta-analysis showed that there was insufficient data to justify the exclusion of anti-EGFR monoclonal antibodies, antiangiogenic agents should be preferred in the first-line setting. Despite the lack of a randomized phase 3 study dedicated to BRAF-mutated CRC, chemotherapy intensification combining a quadruple association of 5-fluorouracil, oxaliplatin, irinotecan (FOLFOXIRI), and bevacizumab seems like a valid option. Although first results with BRAF inhibitors as single agents in BRAF-mutated CRC were disappointing, their association with therapies targeting the MAPK pathway seems to overcome the primary resistance to BRAF inhibition. In the field of sporadic CRC, the BRAF mutation is strongly associated with MMR deficiency. Considering breakthrough results of immune checkpoint inhibitors in dMMR repair tumors, determination of the MMR status appears to be mandatory. Given the dramatic prognosis conferred by the BRAF mutation, patients with BRAF-mutated advanced CRC need to be systematically identified and proposed for clinical trial enrolment in order to benefit from innovative therapies.

A Multikinase and DNA-PK Inhibitor Combination Immunomodulates Melanomas, Suppresses Tumor Progression, and Enhances Immunotherapies

Combination therapies have the potential to improve outcomes in melanoma patients but have not yet been clinically efficacious. Here, we used high-throughput flow cytometry-based screening to identify and characterize candidate therapies that might synergize with and augment T-cell immunotherapy efficacy. Two lead therapies, regorafenib (Reg) and NU7441, were selected based on their ability to alter a variety of immunomodulatory proteins, including CD55, CD73, CD155, programmed death-ligand 1 (PD-L1), nerve growth factor receptor (NGFR), and HLA class I in a heterogeneous panel of melanomas. The therapies also upregulated several melanoma antigens, inhibited proliferation, and perturbed activation of oncogenic signaling pathways in melanomas. T cells treated with the therapies proliferated normally and exhibited a favorably altered phenotype, including increased CD25, CD28, inducible T-cell costimulator (ICOS), and reduced expression of coinhibitory receptors. Cytokine production was also increased in treated T cells. When administered in mice, REg suppressed melanoma progression in a CD8⁺ T cell-dependent manner when used alone and with various immunotherapies. Additionally, Reg altered the number, phenotype, and function of various T-cell subsets in the tumor microenvironment. These studies reveal that Reg and NU7441 influence the immunobiology of both tumor cells and T cells and enhance the efficacy of various immunotherapies. Cancer Immunol Res; 5(9); 790-803. ©2017 AACR.

Impact of Age on Outcomes with Immunotherapy for Patients with Melanoma

BACKGROUND

Monoclonal antibodies (mAb) targeting PD-1/PD-L1 have revolutionized melanoma treatment, yet data regarding effectiveness and tolerability across age groups is limited. We sought to determine the impact of age on overall survival (OS), progression-free survival (PFS), and rates of immune-mediated toxicities in patients treated with anti-PD-1/anti-PD-L1 mAb at two academic medical centers.

METHODS

We retrospectively collected data on all patients with metastatic melanoma treated with anti-PD-1/PD-L1 mAb between May 2009 and April 2015. We used Kaplan-Meier and Cox regression analyses to assess OS and PFS and identify factors associated with these outcomes. We also compared rates of autoimmune toxicity across age groups.

RESULTS

Of 254 patients, 57 (22.4%) were <50 years old, 85 (33.5%) were age 50-64, 65 (25.6%) were age 65-74, and 47 (18.5%) were ≥75 years. Across age groups, no differences existed in median OS (age <50: 22.9 months, age 50-64: 25.3 months, age 65-74: 22.0 months, age ≥75: 24.3 months) or PFS (age <50: 4.1 months, age 50-64: 6.5 months, age 65-74: 5.4 months, age ≥75: 7.9 months). The presence of liver metastases and elevated pre-treatment lactate dehydrogenase (LDH) were associated with reduced OS. Presence of liver metastasis, pretreatment LDH, BRAF mutation, and type of melanoma correlated with PFS. Overall, 110 patients (43.3%) experienced immune-mediated toxicities; 25 (9.8%) had colitis and 26 (10.2%) had endocrine toxicity. Rates of colitis, hepatitis, and pneumonitis did not differ across age groups.

CONCLUSION

We demonstrated that patients could safely tolerate anti-PD1/PDL-1 mAb therapy and achieve similar outcomes regardless of their age.

IMPLICATIONS FOR PRACTICE

Immunotherapy has revolutionized treatment for patients with metastatic melanoma, yet data are lacking regarding the effectiveness and tolerability of these treatments for older patients. In this study, we demonstrated that patients with melanoma safely tolerate immunotherapy and achieve similar outcomes regardless of their age. Specifically, we utilized data from two academic cancer centers and found no significant difference in overall survival, progression free survival, or immune-related toxicities, other than arthritis, across age groups. As the population ages, studies such as this will become critical to help us understand how best to treat older adults with cancer.

A review of binimetinib for the treatment of mutant cutaneous melanoma

Although significant progress has been made in the treatment of unresectable or metastatic melanoma, at least half of all advanced melanoma patients eventually progress and pass away due to their disease. In particular, patients with NRAS-mutated melanoma still face limited therapeutic options, with immunotherapy being the current treatment type of choice. Binimetinib is a selective inhibitor of MEK, a central kinase in the tumor-promoting MAPK pathway. The results of a recent Phase III trial rendered binimetinib the first targeted therapy agent to significantly improve progression-free survival in NRAS-mutated melanoma. This review will summarize the development and clinical data of binimetinib in melanoma in general and also explore the potential future role of this substance as single agent or combination therapy.

Treatment Outcomes for Metastatic Melanoma of Unknown Primary in the New Era: A Single-Institution Study and Review of the Literature

BACKGROUND

Metastatic melanoma of unknown primary (MUP) is uncommon, biologically ill defined, and clinically understudied. MUP outcomes are seldom reported in clinical trials. In this study, we analyze responses of MUP patients treated with systemic therapy in an attempt to inform treatment guidelines for this unique population.

METHODS

New York University (NYU)'s prospective melanoma database was searched for MUP patients treated with systemic therapy. PubMed and Google Scholar were searched for MUP patients treated with immunotherapy or targeted therapy reported in the literature, and their response and survival data were compared to the MUP patient data from NYU. Both groups' response data were compared to those reported for melanoma of known primary (MKP).

RESULTS

The MUP patients treated at NYU had better outcomes on immunotherapy but worse on targeted therapy than the MUP patients in the literature. The NYU MUP patients and those in the literature had worse outcomes than the majority-MKP populations in 10 clinical trial reports.

CONCLUSIONS

Our study suggests that MUP patients might have poorer outcomes on systemic therapy as compared to MKP patients. Our cohort was small and limited data were available, highlighting the need for increased reporting of MUP outcomes and multi-institutional efforts to understand the mechanism behind the observed differences.

Influences of BRAF Inhibitors on the Immune Microenvironment and the Rationale for Combined Molecular and Immune Targeted Therapy

The identification of key driver mutations in melanoma has led to the development of targeted therapies aimed at BRAF and MEK, but responses are often limited in duration. There is growing evidence that MAPK pathway activation impairs antitumor immunity and that targeting this pathway may enhance responses to immunotherapies. There is also evidence that immune mechanisms of resistance to targeted therapy exist, providing the rationale for combining targeted therapy with immunotherapy. Preclinical studies have demonstrated synergy in combining these strategies, and combination clinical trials are ongoing. It is, however, becoming clear that additional translational studies are needed to better understand toxicity, proper timing, and sequence of therapy, as well as the utility of multidrug regimens and effects of other targeted agents on antitumor immunity. Insights gained through translational research in preclinical models and clinical studies will provide mechanistic insight into therapeutic response and resistance and help devise rational strategies to enhance therapeutic responses.

Photoaging Mobile Apps as a Novel Opportunity for Melanoma Prevention: Pilot Study

Background

Around 90% of melanomas are caused by ultraviolet (UV) exposure and are therefore eminently preventable. Unhealthy tanning behavior is mostly initiated in early adolescence, often with the belief that it increases attractiveness; the problems related to skin atrophy and malignant melanoma are too far in the future to fathom. Photoaging desktop programs, in which an image is altered to predict future appearance, have been successful in positively influencing behavior in adiposity or tobacco prevention settings.

Objective

To develop and test a photoaging app designed for melanoma prevention.

Methods

We harnessed the widespread availability of mobile phones and adolescents’ interest in appearance to develop a free mobile app called Sunface. This app has the user take a self-portrait (ie, a selfie), and then photoages the image based on Fitzpatrick skin type and individual UV protection behavior. Afterward, the app explains the visual results and aims at increasing self-competence on skin cancer prevention by providing guideline recommendations on sun protection and the ABCDE rule for melanoma self-detection. The underlying aging algorithms are based on publications showing UV-induced skin damage by outdoor as well as indoor tanning. To get a first impression on how well the app would be received in a young target group, we included a total sample of 25 students in our cross-sectional pilot study with a median age of 22 (range 19-25) years of both sexes (11/25, 44% female; 14/25, 56% male) attending the University of Essen in Germany.

Results

The majority of enrolled students stated that they would download the app (22/25, 88%), that the intervention had the potential to motivate them to use sun protection (23/25, 92%) and that they thought such an app could change their perceptions that tanning makes you attractive (19/25, 76%). Only a minority of students disagreed or fully disagreed that they would download such an app (2/25, 8%) or that such an app could change their perceptions on tanning and attractiveness (4/25, 16%).

Conclusions

Based on previous studies and the initial study results presented here, it is reasonable to speculate that the app may induce behavioral change in the target population. Further work is required to implement and examine the effectiveness of app-based photoaging interventions within risk groups from various cultural backgrounds.

Efficient treatment of a metastatic melanoma patient with a combination of BRAF and MEK inhibitors based on circulating tumor DNA analysis: a case report

Background

Fixed tissues are the standard samples used in routine practice for molecular testing. But sometimes tissues are lacking or difficult to obtain. In these cases, circulating tumor DNA released from tumor cells can be used as an alternative source of tumor DNA.

Case presentation

We present the case of a 63-year-old Caucasian woman with a metastatic melanoma and a very poor performance status. A plasma sample was tested and the BRAF p.V600E mutation was detected. Based on this result, a treatment combining a BRAF inhibitor and a MEK inhibitor was immediately started. This patient achieved a complete response. In addition, by repeating the plasma test, we could obtain a precise kinetic of release of mutated BRAF DNA in plasma.

Conclusions

We report here for the first time the efficient treatment of a metastatic melanoma patient on the basis of circulating tumor DNA analysis. This urgent treatment provided a dramatic response in a patient with a very poor initial condition. The kinetic data most likely reflect treatment efficacy.

Meningeal melanomatosis following discontinuation of dabrafenib: implications for the maintenance of long-term complete remission

A subset of 10-20% of patients under continuous BRAF inhibitor monotherapy achieve long-term progression-free and overall survival. Definitive criteria for the safe cessation of BRAF inhibitor monotherapy in treatment-responsive melanoma patients are lacking. We report a patient who remained in complete remission (CR) for 5 years under dabrafenib. The treatment was withdrawn because of concerns about cardiac toxicity. Four months thereafter the patient developed neurological symptoms, including diplopia and bilateral visual loss. Meningeal melanomatosis and parenchymal brain metastases were diagnosed. Extracerebral metastases were excluded. Reinduction of dabrafenib, combined with trametinib, led to the rapid relief of the neurological symptoms, and a partial remission was confirmed radiologically. Unfortunately, the response was not maintained and the patient died 9 months later. This observation demonstrates that discontinuation of BRAF inhibition can result in loss of disease control. On the basis of this observation, we suggest that BRAF-targeted therapy should be withdrawn only when the risks of continued treatment exceed the risk for disease relapse. However, future studies are urgently required to confirm and quantify the risk for rapid disease relapse following withdrawal of BRAF inhibitor monotherapy.

BRAF Inhibitors Amplify the Proapoptotic Activity of MEK Inhibitors by Inducing ER Stress in NRAS-Mutant Melanoma

Purpose: NRAS mutations in malignant melanoma are associated with aggressive disease requiring rapid antitumor intervention, but there is no approved targeted therapy for this subset of patients. In clinical trials, the MEK inhibitor (MEKi) binimetinib displayed modest antitumor activity, making combinations a requisite. In a previous study, the BRAF inhibitor (BRAFi) vemurafenib was shown to induce endoplasmic reticulum (ER) stress that together with inhibition of the RAF-MEK-ERK (MAPK) pathway amplified its proapoptotic activity in BRAF-mutant melanoma. The present study investigated whether this effect might extent to NRAS-mutant melanoma, in which MAPK activation would be expected.Experimental Design and Results: BRAFi increased pERK, but also significantly increased growth inhibition and apoptosis induced by the MEKi in monolayer, spheroids, organotypic, and patient-derived tissue slice cultures of NRAS-mutant melanoma. BRAFi such as encorafenib induced an ER stress response via the PERK pathway, as detected by phosphorylation of eIF2α and upregulation of the ER stress-related factors ATF4, CHOP, and NUPR1 and the proapoptotic protein PUMA. MEKi such as binimetinib induced the expression of the proapoptotic protein BIM and activation of the mitochondrial pathway of apoptosis, the latter of which was enhanced by combination with encorafenib. The increased apoptotic rates caused by the combination treatment were significantly reduced through siRNA knockdown of ATF4 and BIM, confirming its critical roles in this process.Conclusions: The data presented herein encourage further advanced in vivo and clinical studies to evaluate MEKi in combination with ER stress inducing BRAFi as a strategy to treat rapidly progressing NRAS-mutant melanoma. Clin Cancer Res; 23(20); 6203-14. ©2017 AACR.

Unusual Skin Carcinomas Induced by BRAF Inhibitor for Metastatic Melanoma: A Case Report

The most frequently reported skin tumours during treatment with targeted therapies for BRAF (B type Rapidly Accelerated Fibrosarcoma kinase) mutated metastatic melanoma are squamous cell carcinomas (SCCs). Basal cell carcinomas (BCCs) have been described in such setting, but no cases of multiple and recurring tumours have been reported so far. A patient with a history of chronic sun exposure and more than 10 BCCs removed since 1998 started treatment with vemurafenib for BRAF mutated metastatic melanoma. Therapy was complicated by sporadic episodes of atrial fibrillation and by the development of recurrent, multiple and diffuse BCCs. So, vemurafenib was discontinued and dabrafenib and trametinib were started. Since then, only four BCCs occurred in the patient. Histopathological re-examination showed that most BCCs occurred under vemurafenib presented with squamous features. Such characteristic was significantly less evident before therapy start and in lesions removed under treatment with dabrafenib and trametinib. BRAF inhibition (BRAFi) without MEK inhibition induces mitogen activated kinases overactivation, with consequent skin toxicity and acquired drug resistance. The BCCs removed from our patient showed squamous features, more evident during vemurafenib monotherapy. Both the switch from vemurafenib to dabrafenib and the addition of MEK inhibitor (MEKi) might have reduced the incidence of BCCs and their squamous differentiation.

Variation of mutant allele frequency in NRAS Q61 mutated melanomas

BACKGROUND

Somatic mutations of BRAF or NRAS activating the MAP kinase cell signaling pathway are present in 70% of cutaneous melanomas. The mutant allele frequency of BRAF V600E (M%BRAF) was recently shown to be highly heterogeneous in melanomas. The present study focuses on the NRAS Q61 mutant allele frequency (M%NRAS).

METHODS

Retrospective quantitative analyze of 104 NRAS mutated melanomas was performed using pyrosequencing. Mechanisms of M%NRAS imbalance were studied by fluorescence in situ hybridization (FISH) and microsatellite analysis.

RESULTS

M%NRAS was increased in 27.9% of cases. FISH revealed that chromosome 1 instability was the predominant mechanism of M%NRAS increase, with chromosome 1 polysomy observed in 28.6% of cases and intra-tumor cellular heterogeneity with copy number variations of chromosome 1/NRAS in 23.8%. Acquired copy-neutral loss of heterozygosity (LOH) was less frequent (19%). However, most samples with high M%NRAS had only one copy of NRAS locus surrounding regions suggesting a WT allele loss. Clinical characteristics and survival of patients with either <60% or ≥60% of M%NRAS were not different.

CONCLUSION

As recently shown for M%BRAF, M%NRAS is highly heterogeneous. The clinical impacts of high M%NRAS should be investigated in a larger series of patients.

Dabrafenib plus trametinib in patients with BRAFV600-mutant melanoma brain metastases (COMBI-MB): a multicentre, multicohort, open-label, phase 2 trial

BACKGROUND

Dabrafenib plus trametinib improves clinical outcomes in BRAFV600-mutant metastatic melanoma without brain metastases; however, the activity of dabrafenib plus trametinib has not been studied in active melanoma brain metastases. Here, we report results from the phase 2 COMBI-MB trial. Our aim was to build on the current body of evidence of targeted therapy in melanoma brain metastases through an evaluation of dabrafenib plus trametinib in patients with BRAFV600-mutant melanoma brain metastases.

METHODS

This ongoing, multicentre, multicohort, open-label, phase 2 study evaluated oral dabrafenib (150 mg twice per day) plus oral trametinib (2 mg once per day) in four patient cohorts with melanoma brain metastases enrolled from 32 hospitals and institutions in Europe, North America, and Australia: (A) BRAFV600E-positive, asymptomatic melanoma brain metastases, with no previous local brain therapy, and an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1; (B) BRAFV600E-positive, asymptomatic melanoma brain metastases, with previous local brain therapy, and an ECOG performance status of 0 or 1; (C) BRAFV600D/K/R-positive, asymptomatic melanoma brain metastases, with or without previous local brain therapy, and an ECOG performance status of 0 or 1; and (D) BRAFV600D/E/K/R-positive, symptomatic melanoma brain metastases, with or without previous local brain therapy, and an ECOG performance status of 0, 1, or 2. The primary endpoint was investigator-assessed intracranial response in cohort A in the all-treated-patients population. Secondary endpoints included intracranial response in cohorts B, C, and D. This study is registered with ClinicalTrials.gov, number NCT02039947.

FINDINGS

Between Feb 28, 2014, and Aug 5, 2016, 125 patients were enrolled in the study: 76 patients in cohort A; 16 patients in cohort B; 16 patients in cohort C; and 17 patients in cohort D. At the data cutoff (Nov 28, 2016) after a median follow-up of 8·5 months (IQR 5·5-14·0), 44 (58%; 95% CI 46-69) of 76 patients in cohort A achieved an intracranial response. Intracranial response by investigator assessment was also achieved in nine (56%; 95% CI 30-80) of 16 patients in cohort B, seven (44%; 20-70) of 16 patients in cohort C, and ten (59%; 33-82) of 17 patients in cohort D. The most common serious adverse events related to study treatment were pyrexia for dabrafenib (eight [6%] of 125 patients) and decreased ejection fraction (five [4%]) for trametinib. The most common grade 3 or worse adverse events, regardless of study drug relationship, were pyrexia (four [3%] of 125) and headache (three [2%]).

INTERPRETATION

Dabrafenib plus trametinib was active with a manageable safety profile in this melanoma population that was consistent with previous dabrafenib plus trametinib studies in patients with BRAFV600-mutant melanoma without brain metastases, but the median duration of response was relatively short. These results provide evidence of clinical benefit with dabrafenib plus trametinib and support the need for additional research to further improve outcomes in patients with melanoma brain metastases.

FUNDING

Novartis.

Targeting BRAF-Mutant Non-Small Cell Lung Cancer: From Molecular Profiling to Rationally Designed Therapy

Non-small cell lung cancer (NSCLC) remains the leading cause of cancer-related deaths globally. However, the identification of oncogenic driver alterations involved in the initiation and maintenance of NSCLC, such as epidermal growth factor receptor mutations and anaplastic lymphoma kinase translocation, has led to the development of novel therapies that directly target mutant proteins and associated signaling pathways, resulting in improved clinical outcomes. As sequencing techniques have improved, the molecular heterogeneity of NSCLC has become apparent, leading to the identification of a number of potentially actionable oncogenic driver mutations. Of these, one of the most promising therapeutic targets is B-Raf proto-oncogene, serine/threonine kinase (BRAF). Mutations in BRAF, observed in 2%-4% of NSCLCs, typically lead to constitutive activation of the protein and, as a consequence, lead to activation of the mitogen-activated protein kinase signaling pathway. Direct inhibition of mutant BRAF and/or the downstream mitogen-activated protein kinase kinase (MEK) has led to prolonged survival in patients with BRAF-mutant metastatic melanoma. This comprehensive review will discuss the clinical characteristics and prognostic implications of BRAF-mutant NSCLC, the clinical development of BRAF and MEK inhibitors from melanoma to NSCLC, and practical considerations for clinicians involving BRAF mutation screening and the choice of targeted therapy.

IMPLICATIONS FOR PRACTICE

Personalized medicine has begun to provide substantial benefit to patients with oncogene-driven non-small cell lung cancer (NSCLC). However, treatment options for patients with oncogenic driver mutations lacking targeted treatment strategies remain limited. Direct inhibition of mutant B-Raf proto-oncogene, serine/threonine kinase (BRAF) and/or downstream mitogen-activated protein kinase kinase (MEK) has the potential to change the course of the disease for patients with BRAF-mutant NSCLC, as it has in BRAF-mutant melanoma. Optimization of screening strategies for rare mutations and the choice of appropriate agents on an individual basis will be key to providing timely and successful intervention.

Perioperative BRAF inhibitors in locally advanced stage III melanoma

BACKGROUND AND OBJECTIVES

Stage III malignant melanoma is a heterogeneous disease where those cases deemed marginally resectable or irresecatble are frequently incurable by surgery alone. Targeted therapy takes advantage of the high incidence of BRAF mutations in melanomas, most notably the V600E mutation. These agents have rarely been used in a neoadjuvant setting prior to surgery.

METHODS

Thirteen consecutive patients with confirmed BRAF^V600E regionally advanced melanoma deemed marginally resectable or irrresectable, were treated with BRAF inhibiting agents, prior to undergoing surgery. The primary outcome measures were a successful resection and pathological response. Disease-free survival was a secondary outcome measure.

RESULTS

Overall, 12/13 patients showed a marked clinical responsiveness to medical treatment, enabling a macroscopically successful resection in all cases. Four patients had a complete pathological response with no viable tumor evident in the resected specimens and eight patients showed evidence of minimally residual tumor with extensive tumoral necrosis and fibrosis. One patient progressed and died before surgery. At a median follow up of 20 months, 10 patients remain free of disease.

CONCLUSIONS

Perioperative treatment with BRAF inhibiting agents in BRAFV600E mutated Stage III melanoma patients facilitates surgical resection and affords satisfactory disease free survival.

Clinical features of serous retinopathy observed with cobimetinib in patients with BRAF-mutated melanoma treated in the randomized coBRIM study

BACKGROUND

Serous chorioretinopathy has been associated with MEK inhibitors, including cobimetinib. We describe the clinical features of serous retinopathy observed with cobimetinib in patients with BRAF V600-mutated melanoma treated in the Phase III coBRIM study.

METHODS

In the coBRIM study, 493 patients were treated in two randomly assigned treatment groups: cobimetinib and vemurafenib (n = 247) or vemurafenib (n = 246). All patients underwent prospective ophthalmic examinations at screening, at regular intervals during the study, and whenever ocular symptoms developed. Patients with serous retinopathy were identified in the study database using a group of relevant and synonymous adverse event terms.

RESULTS

Eighty-six serous retinopathy events were reported in 70 patients (79 events in 63 cobimetinib and vemurafenib-treated patients vs seven events in seven vemurafenib-treated patients). Most patients with serous retinopathy identified by ophthalmic examination had no symptoms or had mild symptoms, among them reduced visual acuity, blurred vision, dyschromatopsia, and photophobia. Serous retinopathy usually occurred early during cobimetinib and vemurafenib treatment; median time to onset was 1.0 month. Most events were managed by observation and continuation of cobimetinib without dose modification and resolved or were resolving by the data cutoff date (19 Sept 2014).

CONCLUSIONS

Cobimetinib treatment was associated with serous retinopathy in patients with BRAF V600-mutated melanoma. Retinopathy was generally asymptomatic or mild. Periodic ophthalmologic evaluations at regular intervals and at the manifestation of any visual disturbance are recommended to facilitate early detection and resolution of serous retinopathy while patients are taking cobimetinib. Trial Registration Clinicaltrials.gov (NCT01689519). First received: September 18, 2012.

Overcoming resistance to targeted therapy with immunotherapy and combination therapy for metastatic melanoma

Resistance to targeted therapy is an ongoing problem for the successful treatment of Stage IV metastatic melanoma. For many patients, the use of targeted therapies, such as BRAF kinase inhibitors, were initially promising yet resistance inevitably occurred. Even after combining BRAF kinase inhibitors with MEK pathway inhibitors to offset re-activation of the MAP kinase pathway, resistance is still documented. Similarly, outcomes with immune checkpoint inhibitors as monotherapy were optimistic for some patients without relapse or progression, yet the majority of patients undergoing monotherapy have progressive disease. Will immunotherapy and combination therapy trials overcome resistance in metastatic melanoma? In an effort to treat resistant disease, new clinical trials evaluating the combination of immunotherapy with other therapies, such as kinase inhibitors, adoptive cell therapy, chimeric CD40 ligand to boost costimulation, or a tumor-specific oncolytic virus enhancing granulocyte macrophage colony-stimulating factor (GM-CSF) expression, are currently underway. Updated studies on the mechanisms of resistance, immune escape and options to reinvigorate immune cells support the continued discovery of new and improved forms of therapy.

Phase I Dose-Escalation and -Expansion Study of the BRAF Inhibitor Encorafenib (LGX818) in Metastatic BRAF-Mutant Melanoma

Purpose: Encorafenib, a selective BRAF inhibitor (BRAFi), has a pharmacologic profile that is distinct from that of other clinically active BRAFis. We evaluated encorafenib in a phase I study in patients with BRAFi treatment-naïve and pretreated BRAF-mutant melanoma.Experimental Design: The pharmacologic activity of encorafenib was first characterized preclinically. Encorafenib monotherapy was then tested across a range of once-daily (50-700 mg) or twice-daily (75-150 mg) regimens in a phase I, open-label, dose-escalation and -expansion study in adult patients with histologically confirmed advanced/metastatic BRAF-mutant melanoma. Study objectives were to determine the maximum tolerated dose (MTD) and/or recommended phase II dose (RP2D), characterize the safety and tolerability and pharmacokinetic profile, and assess the preliminary antitumor activity of encorafenib.Results: Preclinical data demonstrated that encorafenib inhibited BRAF V600E kinase activity with a prolonged off-rate and suppressed proliferation and tumor growth of BRAF V600E-mutant melanoma models. In the dose-escalation phase, 54 patients (29 BRAFi-pretreated and 25 BRAFi-naïve) were enrolled. Seven patients in the dose-determining set experienced dose-limiting toxicities. Encorafenib at a dose of 300 mg once daily was declared the RP2D. In the expansion phase, the most common all-cause adverse events were nausea (66%), myalgia (63%), and palmar-plantar erythrodysesthesia (54%). In BRAFi-naïve patients, the overall response rate (ORR) and median progression-free survival (mPFS) were 60% and 12.4 months [95% confidence interval (CI), 7.4-not reached (NR)]. In BRAFi-pretreated patients, the ORR and mPFS were 22% and 1.9 months (95% CI, 0.9-3.7).Conclusions: Once-daily dosing of single-agent encorafenib had a distinct tolerability profile and showed varying antitumor activity across BRAFi-pretreated and BRAFi-naïve patients with advanced/metastatic melanoma. Clin Cancer Res; 23(18); 5339-48. ©2017 AACR.

Precision medicine for hepatocellular carcinoma: driver mutations and targeted therapy

Hepatocellular carcinoma (HCC) is the third most frequent cause of tumor-related mortality and there are an estimated approximately 850,000 new cases annually. Most HCC patients are diagnosed at middle or advanced stage, losing the opportunity of surgery. The development of HCC is promoted by accumulated diverse genetic mutations, which confer selective growth advantages to tumor cells and are called "driver mutations". The discovery of driver mutations provides a novel precision medicine strategy for late stage HCC, called targeted therapy. In this review, we summarized currently discovered driver mutations and corresponding signaling pathways, made an overview of identification methods of driver mutations and genes, and classified targeted drugs for HCC. The knowledge of mutational landscape deepen our understanding of carcinogenesis and promise future precision medicine for HCC patients.

Clinical responses to ERK inhibition in BRAFV600E-mutant colorectal cancer predicted using a computational model

Approximately 10% of colorectal cancers harbor BRAFV600E mutations, which constitutively activate the MAPK signaling pathway. We sought to determine whether ERK inhibitor (GDC-0994)-containing regimens may be of clinical benefit to these patients based on data from in vitro (cell line) and in vivo (cell- and patient-derived xenograft) studies of cetuximab (EGFR), vemurafenib (BRAF), cobimetinib (MEK), and GDC-0994 (ERK) combinations. Preclinical data was used to develop a mechanism-based computational model linking cell surface receptor (EGFR) activation, the MAPK signaling pathway, and tumor growth. Clinical predictions of anti-tumor activity were enabled by the use of tumor response data from three Phase 1 clinical trials testing combinations of EGFR, BRAF, and MEK inhibitors. Simulated responses to GDC-0994 monotherapy (overall response rate = 17%) accurately predicted results from a Phase 1 clinical trial regarding the number of responding patients (2/18) and the distribution of tumor size changes ("waterfall plot"). Prospective simulations were then used to evaluate potential drug combinations and predictive biomarkers for increasing responsiveness to MEK/ERK inhibitors in these patients.

Primary oral malignant melanoma metastasis to the brain and breast: A case report and literature review

Primary oral malignant melanoma is a rare tumor, which is estimated to comprise 0.2–8.0% of all melanoma cases. This type of cancer is fairly uncommon, its prognosis is dismal, and it frequently exhibits a biologically aggressive behavior. The common location of primary oral malignant melanoma is the hard palate and maxillary alveolus. In ~85% of cases, the melanoma will metastasize to the liver, lung, bone and brain early in the course of the disease. The present study reports the case of a 50-year-old premenopausal woman who presented with primary oral malignant spindle cell melanoma (T3bN2aM0) and underwent complete surgical resection followed by an adjuvant course of radiation therapy. After 1 year, the patient presented with sudden onset slurred speech, and upon examination, was found to have left-sided hemiparesis and a hard left breast mass. Workup confirmed breast and brain metastasis. The patient developed lung metastasis 4 weeks later and was referred for palliative care.

[Clinical features and prognosis of Langerhans cell histiocytosis in children: an analysis of 34 cases]

OBJECTIVE

To investigate the clinical features and prognosis of children with Langerhans cell histiocytosis (LCH).

METHODS

A retrospective analysis was performed for the clinical data of 34 children with newly diagnosed LCH.

RESULTS

The 34 children had a median age of 14.5 months (range: 22 d to 60 months). Of all 34 children, 23 were aged 0-2 years and 11 were aged >2 years. There were 17 children in the high-risk group and 17 in the low-risk group. Thirty children received chemotherapy, and the 6-week and 12-month overall response rates were 67% (20/30) and 87% (26/30), respectively. The 3-year overall survival (OS) rate was 86%±6% and the 3-year event-free survival (EFS) rate was 64%±9%. Compared with the low-risk group, the high-risk group had significantly lower 6-week chemotherapy response rate (47% vs 87%; P<0.05), 3-year OS rate (72%±12% vs 100%; P<0.05), and 3-year EFS rate (46%±13% vs 82%±9%; P<0.05). There was no significant difference in the 12-month chemotherapy response rate between the high-risk and low-risk groups (80% vs 93; P>0.05). The high-risk group had a recurrence rate of 27% and a mortality rate of 27%. There were no recurrence or deaths in the low-risk group.

CONCLUSIONS

Children with LCH have a high overall survival rate, but the high-risk patient has a low 6-week response rate of induction chemotherapy and poor long-term prognosis.

Current biologics for treatment of biliary tract cancers

Biliary tract cancers (BTC) is a group of malignancies that arise from the epithelial cells of the biliary tree. These cancers are typically classified by anatomic site of origin: intrahepatic cholangiocarcinoma (IHCC) and extrahepatic cholangiocarcinoma (EHCC), and gallbladder cancer (GBC). To date, complete surgical resection remains the mainstay of treatment especially for earlier stage disease. Unfortunately, most patients present with advanced or metastatic disease, when systemic chemotherapy is the only treatment option. Due to the paucity of effective treatments, BTCs have a dismal prognosis. There is a tremendous need to better understand the disease biology, discover new therapies, and improve clinical outcomes for this challenging disease. Next-generation sequencing has produced a more accurate and detailed picture of the molecular signatures in BTCs. The three BTC histologic subtypes are, in fact, quite molecularly distinct. IHCC commonly contain FGFR2 fusions and IDH 1 and 2 mutations, whereas EHCC and GBC tend to carry mutations in EGFR, HER2, and MAPK pathway. In light of this emerging knowledge, clinical trials have become more biomarker-driven, which allows capturing of subsets of patients that are most likely to respond to certain therapies. Many new and promising targeted therapeutics are currently in the pipeline. Here we review the genetic landscape of BTCs while focusing on new molecular targets and targeted therapeutics currently being investigated in biomarker-driven clinical trials.

Pediatric low-grade gliomas: implications of the biologic era

For the past decade, it has been recognized that pediatric low-grade gliomas (LGGs) and glial-neuronal tumors carry distinct molecular alterations with resultant aberrant intracellular signaling in the Ras-mitogen-activated protein kinase pathway. The conclusions and recommendations of a consensus conference of how best to integrate the growing body of molecular genetic information into tumor classifications and, more importantly, for future treatment of pediatric LGGs are summarized here. There is uniform agreement that molecular characterization must be incorporated into classification and is increasingly critical for appropriate management. Molecular-targeted therapies should be integrated expeditiously, but also carefully into the management of these tumors and success measured not only by radiographic responses or stability, but also by functional outcomes. These trials need to be carried out with the caveat that the long-term impact of molecularly targeted therapy on the developing nervous system, especially with long duration treatment, is essentially unknown.

Promising therapeutics of gastrointestinal cancers in clinical trials

Many novel therapeutics are being developed for patients with cancers along the gastrointestinal (GI) tract. These emerging agents are frequently classified by their biological targets such as tumor growth pathways, tumor metabolism, microenvironment, etc. Some agents targeting cancer growth pathways are based on existing clinically validated therapeutic targets, such as regorafenib for hepatocellular carcinoma (HCC), while other agents focus on newly identified targets, such as FGFR fusions in cholangiocarcinoma. Drugs modifying the immunosuppressive tumor microenvironment have emerged as an attractive area of clinical investigation. Moreover, drugs targeting the stem-cell like qualities of cancer and the tight junction protein claudin 18.2 have generated quite a lot of excitement in the field. In this paper, we will systemically review the recent promising agents and therapeutic strategies in GI cancers.

Next-Generation Sequencing to Guide Treatment of Advanced Melanoma

Next-generation sequencing (NGS) has provided significant insights into the pathogenesis of human malignancies. In advanced melanoma, two therapeutic avenues have appeared and have immediately become the standard of care, i.e. targeted therapy with small molecule inhibitors, and immune checkpoint blockade. Sequencing has always been essential for determining which patients may benefit from targeted therapies (e.g. the presence of BRAF mutations). While sequencing does not currently help recognize which patients might benefit from immune checkpoint blockade, recent data suggest that this may change. Multiple studies have identified tumor mutation profiles associated with patients benefiting from immune checkpoint blockade therapy. These findings suggest comprehensive tumor sequencing may become a critical step for predicting therapy responses to all systemic therapies. In this review, the current and potential future impact of NGS on treatment decisions in advanced melanoma will be summarized and discussed.

Reactivation of the p90RSK-CDC25C Pathway Leads to Bypass of the Ganetespib-Induced G2-M Arrest and Mediates Acquired Resistance to Ganetespib in KRAS-Mutant NSCLC

A subset of non-small cell lung cancers (NSCLC) are dependent upon oncogenic driver mutations, including the most frequently observed driver mutant KRAS, which is associated with a poor prognosis. As direct RAS targeting in the clinic has been unsuccessful to date, use of Hsp90 inhibitors appeared to be a promising therapy for KRAS-mutant NSCLC; however, limited clinical efficacy was observed due to rapid resistance. Furthermore, the combination of the Hsp90 inhibitor (Hsp90i), ganetespib, and docetaxel was tested in a phase III clinical trial and failed to demonstrate benefit. Here, we investigated the mechanism(s) of resistance to ganetespib and explored why the combination with docetaxel failed in the clinic. We have not only identified a critical role for the bypass of the G₂-M cell-cycle checkpoint as a mechanism of ganetespib resistance (GR) but have also found that GR leads to cross-resistance to docetaxel. Reactivation of p90RSK and its downstream target, CDC25C, was critical for GR and mediated the bypass of a G₂-M arrest. Overexpression of either p90RSK or CDC25C lead to bypass of G₂-M arrest and induced ganetespib resistance in vitro and in vivo Moreover, resistance was dependent on p90RSK/CDC25C signaling, as synthetic lethality to ERK1/2, p90RSK, or CDC25C inhibitors was observed. Importantly, the combination of ganetespib and p90RSK or CDC25C inhibitors was highly efficacious in parental cells. These studies provide a way forward for Hsp90 inhibitors through the development of novel rationally designed Hsp90 inhibitor combinations that may prevent or overcome resistance to Hsp90i. Mol Cancer Ther; 16(8); 1658-68. ©2017 AACR.

Combination therapy of BRAF inhibitors for advanced melanoma with BRAF V600 mutation: a systematic review and meta-analysis

BACKGROUND

Although BRAF inhibitors have been used to treat advanced melanoma with BRAF mutation, combination strategies are suggested due to acquired resistance to BRAF inhibitors.

OBJECTIVE

To assess the efficacy of BRAF inhibitor-based combination therapy for the treatment of advanced melanoma with BRAF mutation.

METHODS

We conducted a systematic review and meta-analysis of studies that compared BRAF inhibitor-based combination therapy with BRAF inhibitor monotherapy. We searched MEDLINE, EMBASE, the Cochrane Library and relevant conference proceedings. The random-effects inverse variance and Mantel-Haenszel methods were used to pool the results.

RESULTS

Four randomized controlled trials and one cohort study were identified. A combination therapy with BRAF inhibitors and MEK inhibitors was used in all studies. The combined hazard ratios of overall survival (OS) and progression-free survival (PFS) comparing combination therapy with monotherapy were 0.70 [95% confidence interval (CI) 0.62-0.78] and 0.59 (95% CI 0.55-0.63), respectively. The combined risk ratio of objective response rate (ORR) was 1.30 (95% CI 1.20-1.40), which meant more patients achieved complete/partial responses in combination therapy group than those in the monotherapy group.

CONCLUSIONS

Combination therapy with BRAF inhibitors and MEK inhibitors significantly improved OS, PFS, and ORR in patients with advanced melanoma with BRAF mutation.

mTORC1/autophagy-regulated MerTK in mutant BRAFV600 melanoma with acquired resistance to BRAF inhibition

BRAF inhibitors (BRAFi) and the combination therapy of BRAF and MEK inhibitors (MEKi) were recently approved for therapy of metastatic melanomas harbouring the oncogenic BRAFV600 mutation. Although these therapies have shown pronounced therapeutic efficacy, the limited durability of the response indicates an acquired drug resistance that still remains mechanistically poorly understood at the molecular level. We conducted transcriptome gene profiling in BRAFi-treated melanoma cells and identified that Mer tyrosine kinase (MerTK) is specifically upregulated. MerTK overexpression was demonstrated not only in melanomas resistant to BRAFi monotherapy (5 out of 10 samples from melanoma patients) but also in melanoma resistant to BRAFi+MEKi (1 out of 3), although MEKi alone does not affect MerTK. Mechanistically, BRAFi-induced activation of Zeb2 stimulates MerTK in BRAFV600 melanoma through mTORC1-triggered activation of autophagy. Co-targeting MerTK and BRAFV600 significantly reduced tumour burden in xenografted mice, which was pheno-copied by co-inhibition of autophagy and mutant BRAFV600.

Ubiquitination in melanoma pathogenesis and treatment

Melanoma is one of the most aggressive skin cancers with fiercely increasing incidence and mortality. Since the progressive understanding of the mutational landscape and immunologic pathogenic factors in melanoma, the targeted therapy and immunotherapy have been recently established and gained unprecedented improvements for melanoma treatment. However, the prognosis of melanoma patients remains unoptimistic mainly due to the resistance and nonresponse to current available drugs. Ubiquitination is a posttranslational modification which plays crucial roles in diverse cellular biological activities and participates in the pathogenesis of various cancers, including melanoma. Through the regulation of multiple tumor promoters and suppressors, ubiquitination is emerging as the key contributor and therefore a potential therapeutic target for melanoma. Herein, we summarize the current understanding of ubiquitination in melanoma, from mechanistic insights to clinical progress, and discuss the prospect of ubiquitination modification in melanoma treatment.

Targeting GPNMB with glembatumumab vedotin: Current developments and future opportunities for the treatment of cancer

GPNMB has emerged as an immunomodulator and an important positive mediator of tumor progression and metastasis in numerous solid cancers. Tumor intrinsic GPNMB-mediated effects on cellular signaling, coupled with the ability of GPNMB to influence the primary tumor and metastatic microenvironments in a non-cell autonomous fashion, combine to augment malignant cancer phenotypes. In addition, GPNMB is often overexpressed in a variety of cancers, making it an attractive therapeutic target. In this regard, glembatumumab vedotin, an antibody-drug conjugate (ADC) that targets GPNMB, is currently in clinical trials as a single agent in multiple cancers. In this review, we will describe the physiological functions of GPNMB in normal tissues and summarize the processes through which GPNMB augments tumor growth and metastasis. We will review the pre-clinical and clinical development of glembatumumab vedotin, evaluate on-going clinical trials, explore emerging opportunities for this agent in new disease indications and discuss exciting possibilities for this ADC in the context of combination therapies.

Management of Treatment-Related Adverse Events with Agents Targeting the MAPK Pathway in Patients with Metastatic Melanoma

Tremendous progress has been made in the clinical landscape of advanced-stage BRAF V600-mutant melanoma treatment over the past 5 years. Targeted therapies that inhibit specific steps of the mitogen-activated protein kinase pathway have been shown to provide significant overall treatment benefit in patients with this difficult-to-treat disease. Combination therapy with BRAF and MEK inhibitors (dabrafenib plus trametinib or vemurafenib plus cobimetinib, respectively) has become standard of care. These agents are administered until disease progression or unacceptable toxicity occurs; thus, some patients may remain on maintenance therapy for an extended period of time, while toxicities may result in early discontinuation in other patients. Because the goal of treatment is to prolong survival with minimal impairment of quality of life, drug-related adverse events (AEs) require prompt management to ensure that patients derive the best possible benefit from therapy. Proper management depends on an understanding of which AEs are most likely BRAF or MEK inhibitor associated, thus providing a rationale for dose modification of the appropriate drug. Additionally, the unique safety profile of the chosen regimen may influence patient selection and monitoring. This review discusses the toxicity profiles of these agents, with a focus on the most commonly reported and serious AEs. Here, we offer practical guidance derived from our clinical experience for the optimal management of key drug-related AEs.

IMPLICATIONS FOR PRACTICE

Targeted therapy with BRAF plus MEK inhibitors has become the standard of care for patients with advanced-stage BRAF V600-mutant metastatic melanoma. To provide optimal therapeutic benefit to patients, clinicians need a keen understanding of the toxicity profiles of these drugs. Prompt identification and an understanding of which adverse events are most likely BRAF or MEK inhibitor associated provide a rationale for appropriate therapy adjustments. Practical recommendations derived from clinical experience are provided for management of key drug-related toxicities.

Identification of the Serine Biosynthesis Pathway as a Critical Component of BRAF Inhibitor Resistance of Melanoma, Pancreatic, and Non-Small Cell Lung Cancer Cells

Metastatic melanoma cells commonly acquire resistance to BRAF V600E inhibitors (BRAFi). In this study, we identified serine biosynthesis as a critical mechanism of resistance. Proteomic assays revealed differential protein expression of serine biosynthetic enzymes PHGDH, PSPH, and PSAT1 following vemurafenib (BRAFi) treatment in sensitive versus acquired resistant melanoma cells. Ablation of PHGDH via siRNA sensitized acquired resistant cells to vemurafenib. Inhibiting the folate cycle, directly downstream of serine synthesis, with methotrexate also displayed similar sensitization. Using the DNA-damaging drug gemcitabine, we show that gemcitabine pretreatment sensitized resistant melanoma cells to BRAFis vemurafenib and dabrafenib. We extended our findings to BRAF WT tumor cell lines that are intrinsically resistant to vemurafenib and dabrafenib. Pretreatment of pancreatic cancer and non-small cell lung cancer cell lines with sublethal doses of 50 and 5 nmol/L of gemcitabine, respectively, enhanced killing by both vemurafenib and dabrafenib. The novel aspects of this study are the direct identification of serine biosynthesis as a critical mechanism of BRAF V600E inhibitor resistance and the first successful example of using gemcitabine + BRAFis in combination to kill previously drug-resistant cancer cells, creating the translational potential of pretreatment with gemcitabine prior to BRAFi treatment of tumor cells to reverse resistance within the mutational profile and the WT. Mol Cancer Ther; 16(8); 1596-609. ©2017 AACR.

Circulating tumour DNA sequence analysis as an alternative to multiple myeloma bone marrow aspirates

The requirement for bone-marrow aspirates for genomic profiling of multiple myeloma poses an obstacle to enrolment and retention of patients in clinical trials. We evaluated whether circulating cell-free DNA (cfDNA) analysis is comparable to molecular profiling of myeloma using bone-marrow tumour cells. We report here a hybrid-capture-based Liquid Biopsy Sequencing (LB-Seq) method used to sequence all protein-coding exons of KRAS, NRAS, BRAF, EGFR and PIK3CA in 64 cfDNA specimens from 53 myeloma patients to >20,000 × median coverage. This method includes a variant filtering algorithm that enables detection of tumour-derived fragments present in cfDNA at allele frequencies as low as 0.25% (median 3.2%, range 0.25–46%). Using LB-Seq analysis of 48 cfDNA specimens with matched bone-marrow data, we detect 49/51 likely somatic mutations, with subclonal hierarchies reflecting tumour profiling (96% concordance), and four additional mutations likely missed by bone-marrow testing (>98% specificity). Overall, LB-Seq is a high fidelity adjunct to genetic profiling of bone-marrow in multiple myeloma.

Genetic profiling of multiple myeloma requires painful bone marrow biopsies. Here, the authors develop an alternative non-invasive method for sequencing of five oncogenes in circulating cell-free DNA from myeloma patients, demonstrating 96% concordance with bone marrow tumour profiling results.