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
1122 - Platelets from metastatic cancer patients have increased aggregation and activation
Presenter: Meera Chauhan
Session: Poster Display session 3
Resources:
Abstract
2671 - Luminal B breast cancer prognosis prediction by comprehensive analysis of Homeobox genes
Presenter: Ayako Nakashoji
Session: Poster Display session 3
Resources:
Abstract
2650 - Long non-coding RNA E2F4as promotes tumor progression and predicts patient prognosis in human ovarian cancer
Presenter: Sun-Ae Park
Session: Poster Display session 3
Resources:
Abstract
1462 - FGF19 promotes esophageal squamous cell carcinoma progression by inhibiting autophagy
Presenter: Lisha Ying
Session: Poster Display session 3
Resources:
Abstract
5787 - Proof of concept on the role of ex vivo lung cancer spheroids, cytokines expression and PBMCs profiling in monitoring disease history and response to treatments.
Presenter: Raimondo Di Liello
Session: Poster Display session 3
Resources:
Abstract
5253 - Circulating microRNAs related to DNA damage response as predictors of survival in metastatic non- small cell lung cancer patients treated with platinum-based chemotherapy
Presenter: Dimitris Mavroudis
Session: Poster Display session 3
Resources:
Abstract
5286 - Prognostic value of CTCs in advanced NSCLC patients treated with platinum-based chemotherapy
Presenter: Silvia Calabuig-Fariñas
Session: Poster Display session 3
Resources:
Abstract
5781 - Exosomes in NSCLC as a source of biomarkers
Presenter: Elena Duréndez
Session: Poster Display session 3
Resources:
Abstract
1447 - The role of Pim-1 in the development and progression of papillary thyroid carcinoma
Presenter: Xin Zhu
Session: Poster Display session 3
Resources:
Abstract
1323 - Development and Validation of a RNA-Seq Based Prognostic Signature in Neuroblastoma
Presenter: Jian-Guo Zhou
Session: Poster Display session 3
Resources:
Abstract