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
5763 - cfDNA is an acceptable but insufficient means of characterizing FGFR3 mutation in patients with metastatic urothelial cancer (mUC)
Presenter: Sumanta Pal
Session: Poster Display session 3
Resources:
Abstract
5877 - Efficacy of anti-PD(L)1 treatment in patients with metastatic urothelial cancer based on mRNA- and protein- based PD-L1 determination: Results from the multicentric, retrospective FOsMIC trial
Presenter: Jonas Jarczyk
Session: Poster Display session 3
Resources:
Abstract
5204 - A differential bladder microbiota composition is associated with tumor grade in bladder cancer.
Presenter: Monica Parra-Grande
Session: Poster Display session 3
Resources:
Abstract
4904 - Molecular characterization of metastatic urothelial carcinoma (mUC) in prior or current smokers (PCS) vs non-smokers (NS)
Presenter: Victor Sacristan Santos
Session: Poster Display session 3
Resources:
Abstract
5370 - Evaluation of different diagnostic methods for identification of FGFR alteration in advanced urothelial carcinomas: Proficiency Results based on multiple RNA extraction kits and mutation detection methods
Presenter: Veronika Weyerer
Session: Poster Display session 3
Resources:
Abstract
2579 - Title: Genomic characterization of non-schistosomiasis-related squamous cell carcinoma (NSR-SCC) of the urinary bladder: a retrospective study of potential prognostic and predictive biomarkers
Presenter: Esmail Al-ezzi
Session: Poster Display session 3
Resources:
Abstract
2203 - TiNivo: Tivozanib combined with nivolumab results in prolonged progression free survival in patients with metastatic renal cell carcinoma (mRCC). Final Results.
Presenter: Philippe Barthelemy
Session: Poster Display session 3
Resources:
Abstract
4712 - First-Line Pembrolizumab (pembro) Monotherapy for Advanced Non‒Clear Cell Renal Cell Carcinoma (nccRCC): Updated Follow-Up for KEYNOTE-427 Cohort B
Presenter: Cristina Suárez
Session: Poster Display session 3
Resources:
Abstract
2091 - First-Line Pembrolizumab (pembro) Monotherapy in Advanced Clear Cell Renal Cell Carcinoma (ccRCC): Updated Follow-Up For KEYNOTE-427 Cohort A
Presenter: James Larkin
Session: Poster Display session 3
Resources:
Abstract
2368 - Association Between Depth of Response and Overall Survival: Exploratory Analysis in Patients With Previously Untreated Advanced Renal Cell Carcinoma (aRCC) in CheckMate 214
Presenter: Viktor Grünwald
Session: Poster Display session 3
Resources:
Abstract