Phase I/ II study of vemurafenib in patients with unresectable or recurrent melanoma with BRAF V 600 mutations

Optimal strategy in managing advanced melanoma

The advent of immune checkpoint inhibitors and combination therapy with BRAF inhibitors and MEK inhibitors has dramatically improved the prognosis of advanced melanoma. However, since acral melanoma and mucosal melanoma, which are rare in Western countries but are major subtypes of melanoma in East Asia, including Japan, have a low frequency of BRAF mutations, there are currently no treatment options other than immune checkpoint inhibitors in most such cases. Furthermore, owing to a lower tumor mutation burden, immune checkpoint inhibitors are less effective in acral and mucosal melanoma than in cutaneous melanoma. The aim of this review was to summarize the current status and future prospects for the treatment of advanced melanoma, comparing cutaneous melanoma, acral melanoma, and mucosal melanoma.

Safety and Tolerability of BRAF Inhibitor and BRAF Inhibitor-Based Combination Therapy in Chinese Patients With Advanced Melanoma: A Real World Study

The toxicity spectrum between Chinese and Caucasian patients with melanoma who were treated with BRAF inhibitors (BRAFi) may differ. The purpose of the present study was to assess the safety and tolerability of BRAFi and BRAFi-based combination therapies [MEK inhibitors (MEKi) or anti-programmed death-1 (PD-1) antibody] in Chinese patients with BRAF V600E/K mutation-positive metastatic melanoma. We also investigated whether treatment-related adverse events (AEs) correlated with the prognosis. This retrospective study collected data from 43 patients with BRAF V600E/K mutation-positive metastatic melanoma from a single Chinese cancer center. Of the 43 patients, 12 patients received BRAFi monotherapy, 12 patients received BRAFi+MEKi, and 19 patients received BRAFi combined with the anti-PD-1 antibody. The median follow-up time was 19 months. In the BRAFi group, the most common AEs were rashes, palmoplantar erythrodysesthesia, and arthralgia. Four out of 12 (30%) patients experienced grade 3–4 treatment-related AEs. All grades of AEs in the BRAFi+MEKi group were similar to the BRAFi group, except for higher pyrexia (58.3%) and fewer cutaneous AEs. Three out of 12 (25%) patients experienced grade 3–4 AEs, especially pyrexia (16.7%). In the BRAFi+anti-PD-1 antibody group, AEs were similar to the BRAFi group, except for an increased aminotransferase level (36.8%), increased bilirubin (31.6%), and hypothyroidism (15.8%). Eleven out of 19 (57.9%) patients experienced grade 3–4 AEs and four out of 19 (21%) patients discontinued the therapy due to AEs. Treatment-related hepatotoxicity (trHE), defined as an increase in either alanine aminotransferase (ALT), aspartate transaminase (AST), or bilirubin levels, was the only AE identified as a significant poor-prognosis indicator in this study. The median progression-free survival of patients with trHE (41.9%) was 8 months, whereas it was 18 months for those without trHE [p = 0.046, hazard ratio (HR) = 2.116]. Moreover, this association was independent of medication regimens (p = 0.014, HR = 2.971). The overall response rate of patients with trHE was significantly lower than those without trHE (44.4 vs. 60.0%, p = 0.024), and we observed a similar trend in patients treated with BRAFi, BRAFi+MEKi, and BRAFi+anti-PD-1 antibody. In conclusion, BRAFi and BRAFi-based combination therapies were tolerable with reversible AEs in Chinese patients with melanoma. The trHE in patients receiving BRAFi and BRAFi-based regimens might indicate a poor therapy-related prognosis.

Targeted Therapy and Immunotherapy for Melanoma in Japan

OPINION STATEMENT

Melanoma has several clinically and pathologically distinguishable subtypes, which also differ genetically. Mutation patterns vary among different melanoma subtypes, and efficacy of immune-checkpoint inhibitors differs depending on the subtype of melanoma. In spite of the recent revolution of systemic therapies for advanced melanoma, access to innovative agents is still restricted in many countries. This review article aimed to describe the epidemiology and current status of systemic therapies for melanoma in Japan, where melanoma is rare, but access to innovative agents is available. Acral and mucosal melanomas, which are common in Asian populations, predominantly occur in sun-protected areas and share several biological features. Both the melanomas harbor KIT mutation in approximately 15% of the cases; BRAF or NRAS mutation is found in approximately 10-15% of acral melanoma, but these mutations are less frequent in mucosal melanoma. Combined use of BRAF and MEK inhibitors is one of the standards of care for patients with advanced BRAF-mutant melanoma. In patients with melanoma harboring KIT mutation in exon 11 or 13, KIT inhibitors can be a treatment option; however, none of them have been approved in Japan. Immune-checkpoint inhibitors are expected to be less effective against acral and mucosal melanomas because their somatic mutation burden is lower than those in non-acral cutaneous melanomas. A recently completed phase II trial of nivolumab and ipilimumab combination therapy in 30 Japanese patients with melanoma, including seven with acral and 12 with mucosal melanoma, demonstrated an objective response rate of 43%. Regarding oncolytic viruses, canerpaturev (C-REV, also known as HF10) and talimogene laherparepvec (T-VEC) are currently under review in early phase trials. In the adjuvant setting, dabrafenib plus trametinb combination, nivolumab monotherapy, and pembrolizumab monotherapy were approved in July, August, and December 2018 in Japan, respectively. However, most of the adjuvant phase III trials excluded patients with mucosal melanoma. A phase III trial of adjuvant therapy with locoregional interferon (IFN)-β versus surgery alone is ongoing in Japan (JCOG1309, J-FERON), in which IFN-β is injected directly into the site of the primary tumor postoperatively, so that it would be drained through the untreated lymphatic route to the regional node basin. After the recent approval of these new agents, the JCOG1309 trial will be revised to focus on patients with stage II disease. In conclusion, acral and mucosal melanomas have been treated based on the available medical evidence for the treatment of non-acral cutaneous melanomas. Considering the differences in genetic backgrounds and therapeutic efficacy of immunotherapy, specialized therapeutic strategies for these subtypes of melanoma should be established in the future.

Impact of race on dose selection of molecular-targeted agents in early-phase oncology trials

Background

We examined the impact of race on the maximum tolerated doses (MTD) and final approved doses (FAD) of single-agent molecular-targeted agents (MTA) in North America/Europe (NA/EU) and Asia.

Methods

We searched PubMed and regulatory databases to identify targeted drugs approved globally and compared their FAD and MTD in corresponding phase I/II studies conducted separately in NA/EU and Asia. To evaluate this further, we conducted parallel, prospective, first-in-human studies of DS-7423, a dual PI3K/mTOR inhibitor, in patients with advanced solid tumours in the US and Japan. We pooled and compared the pharmacokinetics (PK), pharmacodynamics (PD), toxicity, and efficacy between these populations.

Results

17 MTA were approved in NA/EU and Asia from 2001 to 2015. Recommended phase 2 doses (RP2D) were identical across races in 14 of 17 (80%) studies and differences were not clinically meaningful. FAD were identical across all regions. 42 and 27 patients from US and Japan, respectively, were enrolled in the phase I studies of DS-7423. Despite differences in race, body weight, and body mass index, the RP2D were 240 mg/day with no differences in toxicities, PK, PD, or efficacy.

Conclusions

Conducting separate clinical trials of single-agent MTA in Caucasian and Asian populations may be redundant.

Vemurafenib in Chinese patients with BRAFV600 mutation-positive unresectable or metastatic melanoma: an open-label, multicenter phase I study

Background

Melanoma is a rare, deadly disease without effective treatment options in China. Vemurafenib is a selective inhibitor of oncogenic BRAF^V600 kinase approved in more than 90 countries, based on results obtained primarily in Caucasian patients. Limited data are available regarding the efficacy and safety of vemurafenib in Asian patients.

Methods

This phase I study investigated the pharmacokinetics, efficacy, and tolerability of vemurafenib (960 mg twice daily) in Chinese patients with BRAF^V600 mutation–positive unresectable or metastatic melanoma. The study included two cohorts: a pharmacokinetic cohort (n = 20) and an expansion cohort (n = 26).

Results

After 21 days of dosing, vemurafenib demonstrated marked accumulation and relatively constant steady-state exposure over the dosing period. Confirmed best overall response rate was 52.2% (95% CI 37.0–67.1%). Median progression-free survival was 8.3 months (95% CI 5.7–10.9%); median overall survival was 13.5 months (95% CI 12.2%–not estimable). The most common adverse events were dermatitis acneiform, arthralgia, diarrhea, blood cholesterol level increase, blood bilirubin level increase, melanocytic nevus, and alopecia. A total of nine grade 3 or 4 adverse events were reported in seven patients (15.2%).

Conclusion

Overall, vemurafenib showed a favorable benefit-risk profile among Chinese patients. Pharmacokinetics, safety, and efficacy were generally consistent with those reported in Caucasian patients.

Trial registration

ClinicalTrials.gov identification: NCT01910181. Registered 29 July 2013, prospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4336-3) contains supplementary material, which is available to authorized users.

Melanoma therapy: Check the checkpoints

Recent mutational and translational studies have revealed that the Ras/Raf/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway plays a key role in melanomagenesis. Mutations in NRAS and BRAF are found in the majority of melanomas resulting in the formation of constitutively active NRAS and BRAF molecules, which leads to the proliferation and survival of melanoma cells through the activation of MEK/ERK signals. Inhibitors of BRAF or MEK significantly extend the progression-free survival and overall survival of melanoma patients compared with conventional chemotherapies. Combining BRAF and MEK inhibitors further enhances the clinical effectiveness. Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) is an immune checkpoint molecule that downregulates T-cell activation by binding to B7 (CD80/CD86) molecules on antigen-presenting cells. Programmed death receptor ligand 1 on melanoma cells negatively regulates T-cell function by binding to the programmed death-1 (PD-1) receptor on T cells. Antibodies against CTLA-4 and PD-1 also enhance the survival of melanoma patients. In this review, we summarize the clinical effectiveness and adverse events of the BRAF inhibitors, MEK inhibitors and anti-immune checkpoint antibodies in melanoma treatment.