Novel insights into the pathogenesis and treatment of NRAS mutant melanoma

The Molecular Evolution of Melanoma Distant Metastases

The evolution of primary melanoma to lymph node and distant metastasis is incompletely understood. We examined the genomic diversity in melanoma progression in matched primary melanomas and lymph node and distant metastases from 17 patients. FISH analysis revealed cancer cell fractions with monotonic copy number alterations, including PHIP gain and PTEN loss, in the metastatic cascade. By contrast, the cancer cell fraction with copy number alterations for BPTF and MITF was reduced in lymph node metastases but increased in distant metastases. Separately, the cancer cell fraction with NCOA3 copy number alteration was comparable between primary tumors and lymph node metastases yet increased in distant metastases. These results suggest enrichment of the phosphoinositide 3-kinase and MITF pathways in the transition through the metastatic cascade. By contrast, next-generation sequencing analysis did not identify a consistent pattern of changes in variant allele frequency while revealing several intriguing findings, including decreased variant allele frequency in distant metastases and distinct drivers in lymph node versus distant metastases. These results provide evidence that distant melanoma metastasis does not always emanate from lymph node metastasis. These results enhance our understanding of clonal patterns of melanoma metastasis, with possible implications for targeted therapy and metastasis competency.

Objective response to immune checkpoint inhibitor therapy in NRAS-mutant melanoma: A systematic review and meta-analysis

Introduction

NRAS mutations are common in melanoma and confer a worse prognosis. Although most patients with metastatic melanoma receive immune checkpoint inhibitors (ICIs), the impact of NRAS mutational status on their efficacy remains under debate.

Methods

We performed a comprehensive literature search across several large databases. Inclusion criteria were trials, cohorts, and large case series that analyzed the primary outcome of objective response rate by NRAS mutational status in patients with melanoma treated with any line of ICI. At least two reviewers independently screened studies using Covidence software, extracted data, and assessed risk of bias. Standard meta-analysis was performed in R with sensitivity analysis and tests for bias.

Results

Data on 1770 patients from ten articles were pooled for meta-analysis, and the objective response rate to ICIs was calculated to compare NRAS-mutant and NRAS-wildtype melanoma. The objective response rate was 1.28 (95% confidence interval: 1.01-1.64). Sensitivity analysis identified the study by Dupuis et al. with influential impact on the pooled effect size and heterogeneity, favoring NRAS-mutant melanoma.

Discussion

In this meta-analysis evaluating the impact of NRAS mutational status on objective response to ICIs in metastatic melanoma, NRAS-mutant cutaneous melanoma demonstrated an increased likelihood of partial or complete tumor response, relative to NRAS-wildtype cutaneous melanoma. Genomic screening for NRAS mutations in patients with metastatic melanoma may improve predictive ability when initiating ICIs.

A first-in-human, phase 1a dose-escalation study of the selective MEK1/2 inhibitor FCN-159 in patients with advanced NRAS-mutant melanoma

BACKGROUND

A phase 1a first-in-human study evaluated the safety/tolerability, preliminary antitumour activity and pharmacokinetics of the oral MEK1/2 inhibitor FCN-159 in Chinese patients with advanced, NRAS-mutant melanoma.

PATIENTS AND METHODS

Patients received a single FCN-159 dose at assigned levels, proceeding to continuous dosing (once daily [QD] for 28-day cycles) if no dose-limiting toxicities (DLTs) occurred within the next 3 days. Dose escalation was initiated after review of data for the previous dose level. The primary end-point was incidence of DLTs after the first dose.

RESULTS

Thirty-three patients were enrolled across nine FCN-159 dose groups (0.2-15 mg QD). One DLT occurred: grade 3 folliculitis in the 15-mg group. There was one grade >3 treatment-emergent adverse event (TEAE), death of unknown aetiology (not FCN-159 related). The most common FCN-159-related TEAE was rash (36.4%), and the incidence of grade ≥3 FCN-159-related TEAEs was 15.2%. Antitumour activity at QD doses <6 mg was limited; therefore, efficacy data are presented only for doses ≥6 mg (n = 21). The objective response and clinical benefit rates were 19.0% (four partial responses) and 52.4%, respectively. Median (95% confidence interval) duration of response and progression-free survival were 4.8 months (2.8-not reached) and 3.8 months (1.8-5.6), respectively. FCN-159 exposure increased dose-proportionately; geometric mean terminal half-life was 29.9-56.9 h.

CONCLUSIONS

FCN-159 was well tolerated and demonstrated promising antitumour activity at doses ≥6 mg QD in patients with advanced, NRAS-mutant melanoma. The recommended phase 2 dose was 12 mg QD.

CLINICALTRIALS

GOV IDENTIFIER

NCT03932253. https://clinicaltrials.gov/ct2/show/NCT03932253.

Validation of a Patient-Derived Xenograft Model for Cervical Cancer Based on Genomic and Phenotypic Characterization

Simple Summary

The rate of total tumor engraftment of patient-derived xenografts is 50% in cervical cancer. These cancers retain their histopathological characteristics. The gene mutations and expression patterns associated with carcinogenesis and infiltration and the expression levels of genes in extracellular vesicles released from the tumors are similar between patient-derived xenograft models and primary tumors. Patient-derived xenograft models of cervical cancer could be potentially useful tools for translational research.

Abstract

Patient-derived xenograft (PDX) models are useful tools for preclinical drug evaluation, biomarker identification, and personalized medicine strategies, and can be developed by the heterotopic or orthotopic grafting of surgically resected tumors into immunodeficient mice. We report the PDX models of cervical cancer and demonstrate the similarities among original and different generations of PDX tumors. Fresh tumor tissues collected from 22 patients with primary cervical cancer were engrafted subcutaneously into NOD.CB17-PrkdcSCID/J mice. Histological and immunohistochemical analyses were performed to compare primary and different generations of PDX tumors. DNA and RNA sequencing were performed to verify the similarity between the genetic profiles of primary and PDX tumors. Total RNA in extracellular vesicles (EVs) released from primary and PDX tumors was also quantified to evaluate gene expression. The total tumor engraftment rate was 50%. Histologically, no major differences were observed between the original and PDX tumors. Most of the gene mutations and expression patterns related to carcinogenesis and infiltration were similar between the primary tumor and xenograft. Most genes associated with carcinogenesis and infiltration showed similar expression levels in the primary tumor and xenograft EVs. Therefore, compared with primary tumors, PDX models could be potentially more useful for translational research.