Combined vemurafenib and fotemustine in patients with BRAF V600 melanoma progressing on vemurafenib

Oxidative Stress-Related Mechanisms in Melanoma and in the Acquired Resistance to Targeted Therapies

Melanoma is a highly aggressive cancer with the poorest prognosis, representing the deadliest form of skin cancer. Activating mutations in BRAF are the most frequent genetic alterations, present in approximately 50% of all melanoma cases. The use of specific inhibitors towards mutant BRAF variants and MEK, a downstream signaling target of BRAF in the MAPK pathway, has significantly improved progression-free and overall survival in advanced melanoma patients carrying BRAF mutations. Nevertheless, despite these improvements, resistance still develops within the first year of therapy in around 50% of patients, which is a significant problem in managing BRAF-mutated advanced melanoma. Understanding these mechanisms is one of the mainstreams of the research on BRAFi/MEKi acquired resistance. Both genetic and epigenetic mechanisms have been described. Moreover, in recent years, oxidative stress has emerged as another major force involved in all the phases of melanoma development, from initiation to progression until the onsets of the metastatic phenotype and chemoresistance, and has thus become a target for therapy. In the present review, we discuss the current knowledge on oxidative stress and its signaling in melanoma, as well as the oxidative stress-related mechanisms in the acquired resistance to targeted therapies.

Treatment beyond progression and locoregional approaches in selected patients with BRAF-mutated metastatic melanoma

The clinical management of BRAF-mutated metastatic melanoma had an important turning point after the introduction of the targeted therapy. Despite the efficacy and good tolerability of this treatment, the development of resistance mechanisms causes disease progression. The aim of this review is to investigate the role of treatment beyond progression and locoregional approaches in BRAF-mutated metastatic melanoma and provide oncologists dealing with this malignancy a useful road map on when and why to choose this strategy.

The article is structured in the form of a narrative review reporting the most significant studies on the subject. Most of the available articles are represented by retrospective studies and case reports, leading to limitations in the final interpretations. Nevertheless, a correct analysis of the selected studies allows the drawing of some conclusions. In well-selected cases, treatment beyond progression could play an important role in the treatment sequence of patients with BRAF-mutated advanced melanoma and would seem to produce good disease control rates and positive survival outcomes. A careful evaluation of the radiological examinations and laboratory tests, based on the clinical conditions, allows the identification of which patients can benefit from this strategy. Such patients are those who, at the time of progression, have favourable features such as a lower performance status according to Eastern Cooperative Oncology Group (ECOG-PS), normal lactate dehydrogenase levels and lower disease burden. The clinical benefit is also consolidated by the addition of locoregional approaches. Locoregional approaches can include electrochemotherapy, radiotherapy or surgery, and their use provides local disease control and a better quality of life for patients.

Treatment Following Progression in Metastatic Melanoma: the State of the Art from Scientific Literature to Clinical Need

INTRODUCTION

In the last few years, the advent of targeted therapy and immunotherapy has improved the management and the prognosis of metastatic melanoma, but the spread of resistance mechanisms can lead to disease progression. The clinical management in this setting can be challenging because the oncologist has to decide what is the best treatment strategy among therapy beyond progression (TBP), therapy change, and the rechallenge approach. This review of the relevant scientific literature is intended to clarify which patients with progressing metastatic melanoma will benefit from continuation of ongoing therapy and which ones will not. The data are based on a total of about 4300 patients coming from the main retrospective studies in the chosen field. The article body is divided into four sections which analyze respectively the targeted therapy beyond progression, the immunotherapy beyond progression, the possible treatment sequences, and finally the rechallenge strategy.

RECENT FINDINGS

Despite the possible approaches of TBP or rechallenge, the patient may not have an optimal response and may need new therapy, which is currently missing. To broaden the pharmacological offer in the fight against melanoma, cancer research is studying new disease targets, like the NRAS, PI3K, and cKIT pathways or combination treatment of targeted therapy plus immunotherapy. Despite the limitations of this work, mainly due to the limited number of studies, their retrospective nature and the lack of comparative studies, the analysis performed allows us to draw some important conclusions: therapy beyond progression, both targeted therapy and immunotherapy, represents a valid treatment option with positive effects on disease control and survival outcomes for patients with low clinical risk, expressed as low disease burden, normal LDH levels, and good performance status; moreover, the prognosis and quality of life of these patients improve when TBP is associated with locoregional treatments. In patients with progressive metastatic melanoma and high clinical risk (high disease burden, high LDH levels, and poor performance status), it is recommended to change therapy, without ever forgetting the possibility of enrolling the patient in a clinical trial. Finally, an efficacious treatment alternative is the rechallenge strategy; this approach consists in a re-treatment with the same drug after a variable interval of discontinuation. Preliminary studies seem to have demonstrated that patients retreated with targeted therapy achieved a greater benefit if they had a low clinical risk and if the drug doublet (BRAF + MEK inhibitors) was used. On the side of immunotherapy, the rechallenge strategy produced a major benefit in patients who prior experienced a severe toxic episode.

Developments in therapy for brain metastases in melanoma patients

Introduction: Cutaneous melanoma brain metastases (MBM) are a major cause of morbidity and mortality. While cytotoxic agents, interferon, or interleukin-2, have been used with some success in extracranial disease, limited efficacy is demonstrated in MBM. The rare patient with long-term survival presented with limited intracranial disease amenable to surgery or radiation therapy. However, the development of targeted therapy and immunotherapy over the last decade has significantly improved overall survival in this formerly devastating presentation of metastatic melanoma.Areas covered: This article reviews the mechanism of brain metastasis, challenges with treating the central nervous system, historical treatment of MBM, and outcomes in clinical trials with targeted therapy and immunotherapy.Expert opinion: The MBM patient population now, more than ever, requires a multidisciplinary approach with surgery, radiation therapy, and the use of newer systemic therapies such as immunotherapy agents and targeted therapy agents. MBM has traditionally been excluded from clinical trials for systemic therapy due to poor survival. However, recent data show overall survival rates have significantly improved, supporting the need for inclusion of MBM patients in systemic therapy clinical trials. Understanding the mechanisms of therapeutic activity in the brain, resistance  mechanisms, and the appropriate multi-modality treatment approach requires further investigation. Nevertheless, these therapies continue to give some hope to patients with historically poor survival.

Novel therapies for advanced skin carcinomas

Advanced skin carcinomas are a serious therapeutic problem. The statistical analysis shows a continuous increase in the incidence of both melanoma and non-melanoma skin cancers. Traditional therapies are characterized by low effectiveness and patients overall survival is not affected by them. By understanding the molecular pathways that lead to the neoplastic transformation and thanks to the knowledge of the immune system, it is possible to use personalized medicine in novel therapies for advanced skin carcinomas.

Melanoma Brain Metastases in the Era of Target Therapies: An Overview

Malignant melanoma is the third most common type of tumor that causes brain metastases. Patients with cerebral involvement have a dismal prognosis and their treatment is an unmet medical need. Brain involvement is a multistep process involving several signaling pathways such as Janus kinase/signal Transducer and Activator of Transcription (JAK/STAT), Phosphoinositide 3-kinase/Protein Kinase B (PI3K/AKT), Vascular Endothelial Growth Factor and Phosphatase and Tensin Homolog (PTEN). Recently therapy that targets the MAPK signaling (BRAF/MEK inhibitors) and immunotherapy (anti-CTLA4 and anti-PD1 agents) have changed the therapeutic approaches to stage IV melanoma. In contrast, there are no solid data about patients with brain metastases, who are usually excluded from clinical trials. Retrospective data showed that BRAF-inhibitors, alone or in combination with MEK-inhibitors have interesting clinical activity in this setting. Prospective data about the combinations of BRAF/MEK inhibitors have been recently published, showing an improved overall response rate. Short intracranial disease control is still a challenge. Several attempts have been made in order to improve it with combinations between local and systemic therapies. Immunotherapy approaches seem to retain promising activity in the treatment of melanoma brain metastasis as showed by the results of clinical trials investigating the combination of anti-CTL4 (Ipilimumab) and anti-PD1(Nivolumab). Studies about the combination or the sequential approach of target therapy and immunotherapy are ongoing, with immature results. Several clinical trials are ongoing trying to explore new approaches in order to overcome tumor resistance. At this moment the correct therapeutic choices for melanoma with intracranial involvement is still a challenge and new strategies are needed.

Phase 1 study of the combination of vemurafenib, carboplatin, and paclitaxel in patients with BRAF-mutated melanoma and other advanced malignancies

BACKGROUND

BRAF inhibitors are effective against selected BRAFV600 -mutated tumors. Preclinical data suggest that BRAF inhibition in conjunction with chemotherapy has increased therapeutic activity.

METHODS

Patients with advanced cancers and BRAF mutations were enrolled into a dose-escalation study (3+3 design) to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLTs).

RESULTS

Nineteen patients with advanced cancers and BRAF mutations were enrolled and received vemurafenib (480-720 mg orally twice a day), carboplatin (area under the curve [AUC] 5-6 intravenously every 3 weeks), and paclitaxel (100-135 mg/m2 intravenously every 3 weeks). The MTD was not reached, and vemurafenib at 720 mg twice a day, carboplatin at AUC 5, and paclitaxel at 135 mg/m2 were the last safe dose levels. DLTs included a persistent grade 2 creatinine elevation (n = 1), grade 3 transaminitis (n = 1), and grade 4 thrombocytopenia (n = 1). Non-dose-limiting toxicities that were grade 3 or higher and occurred in more than 2 patients included grade 3/4 neutropenia (n = 5), grade 3/4 thrombocytopenia (n = 5), grade 3 fatigue (n = 4), and grade 3 anemia (n = 3). Of the 19 patients, 5 (26%; all with melanoma) had a partial response (PR; n = 4) or complete response (CR; n = 1); these responses were mostly durable and lasted 3.1 to 54.1 months. Of the 13 patients previously treated with BRAF and/or mitogen-activated protein kinase kinase (MEK) inhibitors, 4 (31%) had a CR (n = 1) or PR (n = 3). Patients not treated with prior platinum therapy had a higher response rate than those who did (45% vs 0%; P = .045).

CONCLUSIONS

The combination of vemurafenib, carboplatin, and paclitaxel is well tolerated and demonstrates encouraging activity, predominantly in patients with advanced melanoma and BRAFV600 mutations, regardless of prior treatment with BRAF and/or MEK inhibitors.

BRAF kinase inhibitors for treatment of melanoma: developments from early-stage animal studies to Phase II clinical trials

INTRODUCTION

Approximately, 30.4-66.0% of cutaneous melanomas possess a mutation in the BRAF gene that activates downstream signaling through the mitogen-activated protein (MAP) kinase pathway; this provides an attractive target for the treatment of advanced melanoma. Although BRAF inhibitors rapidly suppress melanoma growth, median progression-free survival remains unsatisfactory. Recent clinical trials have investigated drugs that can optimally enhance and prolong the anti-melanoma effects of BRAF inhibitors.

AREAS COVERED

This review discusses the development of BRAF inhibitor-based combination therapies for BRAF-mutant advanced melanoma.

EXPERT OPINION

Future strategies for the treatment of advanced melanoma include novel combination therapies using BRAF/MEK inhibitors and immune checkpoints inhibitors or histone deacetylase inhibitors. These combination therapies might enhance antitumor responses against melanoma, prolonging survival in advanced melanoma patients. Further clinical studies are needed to optimize these novel combination therapies.

Combination Treatment of Patients with BRAF-Mutant Melanoma: A New Standard of Care

Raf-mitogen-activated protein kinase (Raf-MAPK) pathway inhibition with the BRAF inhibitors vemurafenib and dabrafenib, alone or in combination with a MEK inhibitor, has become a standard therapeutic approach in patients with BRAF-mutated metastatic melanoma. Both vemurafenib and dabrafenib have shown good safety and efficacy as monotherapy compared with chemotherapy. However, the duration of response is limited in the majority of patients treated with BRAF inhibitor monotherapy because of the development of acquired resistance. The addition of a MEK inhibitor can improve blockade of the MAPK pathway and may help to overcome resistance and thereby prolong efficacy, as well as reduce cutaneous toxicity. Combinations of BRAF inhibitors and MEK inhibitors (dabrafenib plus trametinib and vemurafenib plus cobimetinib) have been approved for the treatment of BRAF-mutant metastatic melanoma and may become a new standard of care. However, acquired resistance is still a significant concern with BRAF and MEK inhibitor combination therapy, and other strategies are being investigated, including the use of sequential and intermittent schedules. The combination of BRAF or MEK inhibitors with immunotherapy has been shown to hold considerable promise, with several combinations being evaluated in clinical trials. Preliminary results from clinical trials involving triple combination therapy with BRAF-MEK inhibitors and anti-PD-L1 antibodies appear promising and may indicate a new strategy to treat patients with BRAF-mutated metastatic melanoma. Biomarkers are needed to help identify patients with BRAFV600 mutations most likely to benefit from first-line BRAF/MEK inhibitor therapy rather than immunotherapy and vice versa.