Abstract 3454
Background
The clinical benefit of combined treatment with BRAF- and MEK-inhibitors (BRAFi; MEKi) in BRAFV600 mutant (BRAFm) melanoma is limited due to resistance after 6-14 months, associated with emerging secondary mutations. Withholding of treatment leads to reversible hyperactivation of the MAPK pathway, causing transient growth arrest and increase in Reactive Oxygen Species (ROS) in preclinical studies. Treatment of BRAFi/MEKi resistant melanoma cells with vorinostat leads to a further increase in ROS, effectively killing BRAFi resistant cells. In vivo, switch from BRAFi to vorinostat in BRAFi resistant BRAFm melanoma resulted in a decline in tumor volume. Six patients with resistant BRAFm melanoma were treated with vorinostat 360 mg QD continuously. These patients revealed regression of mutant clones and progression of BRAFi sensitive clones. Tumor biopsies showed newly developed secondary MAPK pathway mutations, e.g. NRASQ61H and KRASG12C amplifications at start and a complete absence of these resistant mutations after two weeks of vorinostat. Based on these findings we postulate that BRAFi resistant BRAFm melanoma cells can be eliminated by a short treatment with vorinostat due to killing of tumor cells harboring a secondary mutation in the MAPK pathway. In vitro experiments confirmed this hypothesis.
Trial design
This is a proof of concept study to determine the efficacy of sequential treatment with vorinostat and BRAFi/MEKi in BRAFi resistant BRAFm melanoma. Patients with age ≥ 18 years, WHO performance 0-2 and progression on BRAFi/MEKi are eligible. 26 evaluable patients with resistant BRAFm melanoma will be treated with vorinostat 360 mg continuously for 2 weeks and thereafter switch back to BRAFi/MEKi. The primary aim is to demonstrate ≥ 30% anti-tumor response of progressive lesions according to RECIST 1.1 upon sequenced treatment with vorinostat and BRAFi/MEKi. Secondary endpoints are to demonstrate that emerging resistant clones with a secondary mutation in the MAPK pathway can be detected by ctDNA analysis and purged by short term treatment with vorinostat. Blood and tumor biopsies will be taken for pharmacokinetic, pharmacodynamic and pharmacogenetic exploratory analyses.
Clinical trial identification
NCT02836548.
Editorial acknowledgement
Legal entity responsible for the study
The Netherlands Cancer Institute.
Funding
Oncode.
Disclosure
J.H.M. Schellens: Shareholder / Stockholder / Stock options, and patent holder on oral taxenes: Modra Pharmaceutical. All other authors have declared no conflicts of interest.
Resources from the same session
5544 - Evaluation of a radiomic signature of CD8 cells in patients treated with immunotherapy-radiotherapy in three clinical trials.
Presenter: Roger Sun
Session: Poster Display session 3
Resources:
Abstract
1117 - Biomarkers predictive of overall survival in advanced cancer patients treated with a peptide-based cancer vaccine.
Presenter: Shigetaka Suekane
Session: Poster Display session 3
Resources:
Abstract
1922 - Expression of PD-L1 in plasma exosomes of NSCLC patients and its associations with PD-L1 expression of corresponding tumor tissues
Presenter: Shaorong Yu
Session: Poster Display session 3
Resources:
Abstract
5495 - Patient’s perspective on digital biomarkers in advanced urologic malignancies
Presenter: Severin Rodler
Session: Poster Display session 3
Resources:
Abstract
3166 - A comprehensive Pan-cancer study of FGFR Aberrations in Chinese cancer patients
Presenter: Yang Gao
Session: Poster Display session 3
Resources:
Abstract
3277 - A Systemic Inflammation Response Index (SIRI) correlates with survival and could be a Predictive Factor for mFOLFIRINOX in Metastatic Pancreatic Cancer (PC)
Presenter: Vilma Pacheco-Barcia
Session: Poster Display session 3
Resources:
Abstract
2680 - Circulating biomarkers and risk of immune-related adverse events (irAEs) in patients (pts) with advanced Non-small cell lung cancer (aNSCLC) and metastatic melanoma (mMel)
Presenter: Alberto Pavan
Session: Poster Display session 3
Resources:
Abstract
4066 - Breast cancer in young women of Kazakh population depending on germline mutations: results of next-generation sequencing
Presenter: Dilyara Kaidarova
Session: Poster Display session 3
Resources:
Abstract
5514 - Discovery of an ImmunoTranscriptomics signature in blood for early colorectal cancer detection
Presenter: Paolo Angelino
Session: Poster Display session 3
Resources:
Abstract
1595 - Serum Netrin-1 as a Biomarker for Colorectal Cancer Detection
Presenter: Jinzhou Zhu
Session: Poster Display session 3
Resources:
Abstract