BRAF inhibitor activity in V600R metastatic melanoma--response

The clinical characteristics of melanoma with BRAF V600R mutation: a case series study

Currently, several targeted therapy regimens are approved as first-line treatment in V600E/K-mutant advanced and metastatic melanoma. Patients with the third most common pathologic variant in the BRAF gene, V600R, were not included in BRAF/MEK inhibitors clinical trials, so there is lack of information about the clinical characteristics and predictive value of this mutation in systemic therapy of unresectable disease. We retrospectively reviewed clinical BRAF mutation testing results and the records of melanoma patients at the University of Iowa Hospitals and Clinics from 2011 to 2017. DNA from formalin-fixed, paraffin-embedded tumor specimens were sequenced using a next-generation sequencing panel or dye terminator sequencing covering exon 15 of the BRAF gene. The study protocol was approved by the University of Iowa Institutional Review Board. Nine patients (5.3% of 168 cases with BRAF mutation) were found to have the V600R mutation. We report our experience in treatment of seven patients with V600R-mutant melanoma, whose clinical records were available for review. Four patients in our cohort received BRAF inhibitors. Three patients demonstrated partial objective response to BRAF/MEK targeted therapy. V600R-mutant melanoma accounts for a significant number of cases even in single-institution practices. We believe that testing for BRAF-mutation status should include rare variants of this mutation. From our experience, the high rate of ulceration, male predominance and advanced age at diagnosis are features of melanoma with V600R mutation, which are similar to those reported for V600K mutation. We observed objective response to BRAF/MEK inhibitors in three cases with V600R variant.

The World of Melanoma: Epidemiologic, Genetic, and Anatomic Differences of Melanoma Across the Globe

PURPOSE OF REVIEW

As cancer remains an increasing problem in industrial countries, the incidence of melanoma has risen rapidly in many populations during the last decades and still continues to rise. Current strategies aiming to control the disease have largely focused on improving the understanding of the interplay of causal factors for this cancer.

RECENT FINDINGS

Cutaneous melanoma shows clear differences in incidence, mortality, genomic profile, and anatomic presentation, depending on the country of residence, ethnicity, and socioeconomic status. Known risk factors are multiple atypical nevi, positive family and/or personal history, immune suppressive diseases or treatments, and fair skin phenotype. Besides new adjuvant therapeutic options, changed attitude toward leisure and sun exposure, primary prevention, and early detection are major contributors to disease control. Melanoma is a disease of multifactorial causality and heterogeneous presentation. Its subtypes differ in origin, anatomical site, role of UV radiation, and mutational profile. Better understanding of these differences may improve prevention strategies and therapeutic developments.

Melanoma: What do all the mutations mean?

Melanoma is one of the most highly mutated malignancies, largely as a function of its generation through ultraviolet light and other mutational processes. The wide array of mutations in both "driver" and "passenger" genes can present a confusing array of data for practitioners, particularly within the context of the recent revolutions in targeted and immune therapy. Although mutations in BRAF V600 clearly confer sensitivity to BRAF and mitogen-activated protein kinase kinase (MEK) inhibitors, the clinical implications of most other mutations are less often discussed and understood. In this review, we provide an overview of the high-frequency genomic alterations and their prognostic and therapeutic relevance in melanoma.

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.

Genome variation across cancers scales with tissue stiffness - an invasion-mutation mechanism and implications for immune cell infiltration

Many different types of soft and solid tumors have now been sequenced, and meta-analyses suggest that genomic variation across tumors scales with the stiffness of the tumors' tissues of origin. The opinion expressed here is based on a review of current genomics data, and it considers multiple 'mechanogenomics' mechanisms to potentially explain this scaling of mutation rate with tissue stiffness. Since stiff solid tissues have higher density of fibrous collagen matrix, which should decrease tissue porosity, cancer cell proliferation could be affected and so could invasion into stiff tissues as the nucleus is squeezed sufficiently to enhance DNA damage. Diversification of a cancer genome after constricted migration is now clear. Understanding genome changes that give rise to neo-antigens is important to selection as well as to the development of immunotherapies, and we discuss engineered monocytes/macrophages as particularly relevant to understanding infiltration into solid tumors.

Integrating first-line treatment options into clinical practice: what's new in advanced melanoma?

Melanoma remains a serious form of skin cancer in Europe and worldwide. Localized, early-stage melanomas can usually be treated with surgical excision. However, the prognosis is poorer for patients with advanced disease. Before 2011, treatment for advanced melanoma included palliative surgery and/or radiotherapy, and chemotherapy with or without immunotherapy, such as interleukin-2. As none of these treatments had shown survival benefits in patients with advanced melanoma, European guidelines had recommended that patients be entered into clinical trials. The lack of approved first-line options and varying access to clinical trials meant that European clinicians relied on experimental regimens and chemotherapy-based treatments when no other options were available. Since 2011, ipilimumab, an immuno-oncology therapy, and vemurafenib and dabrafenib, targeted agents that inhibit mutant BRAF, have been approved by the European Medicines Agency for the treatment of advanced melanoma. More recently, the MEK inhibitor, trametinib, received European marketing authorization for use in patients with BRAF mutation-positive advanced melanoma. In 2014, the anti-PD-1 antibody nivolumab was approved as a first-line therapy in Japan. Whereas nivolumab and another anti-PD-1 antibody, pembrolizumab, were approved as second-line therapies in the USA, their recent approval in Europe are for first-line use based on new clinical trial data in this setting. Together these agents are changing clinical practice and making therapeutic decisions more complex. Here, we discuss current and emerging therapeutic options for the first-line treatment of advanced melanoma, and how these therapies can be optimized to provide the best possible outcomes for patients.

Recent advances in the treatment of melanoma with BRAF and MEK inhibitors

Selective inhibition of the mitogen activated protein kinase (MAPK) pathway with either BRAF or MEK inhibition has emerged as the key component for the treatment of BRAF-mutant metastatic melanoma. New evidence from several phase III trials suggests that the combination of BRAF and MEK inhibitors improves tumor response rate and progression-free survival (PFS). Some of the serious adverse events, in particular, the incidence of cutaneous squamous cell carcinoma seen with the monotherapy treatment with a BRAF inhibitor are attenuated with combination therapy, whereas milder side effects such as pyrexia can be more common with combination therapy. Although dose reductions and dose interruptions are slightly more common with combination therapy, overall data supports the notion that combination therapy is safe and improves the outcomes for metastatic melanoma patients compared to single agent BRAF inhibitors.

Non-p.V600E BRAF Mutations Are Common Using a More Sensitive and Broad Detection Tool

OBJECTIVES

To assess the performance of a next-generation sequencing (NGS) platform for the clinical detection of BRAF mutations.

METHODS

In this retrospective quality assessment of an NGS assay, we analyzed BRAF mutations within parts of exons 11 and 15 in 835 neoplastic tissues submitted to our molecular diagnostics laboratory.

RESULTS

The NGS assays detected a BRAF mutation in 5.9% of lung adenocarcinomas, 13% of colorectal cancers, and 44% of melanomas. Mutant allele frequencies were less than 20% in 28% of 88 BRAF-mutated specimens. Two lymph node specimens with subcapsular or infiltrative metastasis showed 1% to 2% mutant alleles. There were 26 unique BRAF mutations in exons 11 and 15, including three novel mutations. Mutations were located outside codon 600 in 39% of BRAF-mutated tumors. Lung adenocarcinomas showed significantly higher non-p.V600E mutations (86%) than did colorectal cancers (23%) and melanomas (34%). The three most common BRAF mutations in lung cancers accounted for only 41% of the observed BRAF mutations (p.D594G [18%], p.V600E [14%], and p.G469A [9%]).

CONCLUSIONS

The NGS assay demonstrated a high analytic sensitivity and a broad reportable range for clinical detection of BRAF mutations. Elucidating the spectrum of non-p. V600E BRAF mutations in different malignancies is a first step toward understanding their clinical significance.

[Systemic treatment of melanoma brain metastases]

Melanomas have a high rate of brain metastases. Both the functional prognosis and the overall survival are poor in these patients. Until now, surgery and radiotherapy represented the two main modalities of treatment. Nevertheless, due to the improvement in the management of the extracerebral melanoma, the systemic treatment may be an option in patients with brain metastases. Immunotherapy with anti-CTLA4 (cytotoxic T-lymphocyte-associated protein 4) - ipilimumab - or BRAF (serine/threonine-protein kinase B-raf) inhibitors - vemurafenib, dabrafenib - has shown efficacy in the management of brain metastases in a- or pauci-symptomatic patients. Studies are ongoing with anti-PD1 (programmed cell death 1) and combinations of targeted therapies associating anti-RAF (raf proto-oncogene, serine/threonine kinase) and anti-MEK (mitogen-activated protein kinase kinase).

Molecular pathology of cutaneous melanoma

Cutaneous melanoma is associated with strong prognostic phenotypic features, such as gender, Breslow's thickness and ulceration, although the biological significance of these variables is largely unknown. It is likely that these features are surrogates of important biological events rather than directly promoting cutaneous melanoma progression. In this article, we address the molecular mechanisms that drive these phenotypic changes. Furthermore, we present a comprehensive overview of recurrent genetic abnormalities, both germline and somatic, in relation to cutaneous melanoma subtypes, ultraviolet exposure and anatomical localization, as well as pre-existing and targeted therapy-induced mutations that may contribute to resistance. The increasing knowledge of critically important oncogenes and tumor-suppressor genes is promoting a transition in melanoma diagnosis, in which single-gene testing will be replaced by multiplex and multidimensional analyses that combine classical histopathological characteristics with the molecular profile for the prognostication and selection of melanoma therapy.