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PLoS One. 2014 Jul 1;9(7):e101286. doi: 10.1371/journal.pone.0101286. eCollection 2014.

Clinical profiling of BCL-2 family members in the setting of BRAF inhibition offers a rationale for targeting de novo resistance using BH3 mimetics.

Author information

1
Division of Surgical Oncology, Massachusetts General Hospital, Boston, Massachusetts, United States of America.
2
Division of Surgical Oncology, Massachusetts General Hospital, Boston, Massachusetts, United States of America; Harvard Medical School, Boston, Massachusetts, United States of America.
3
Division of Medical Oncology, Massachusetts General Hospital Cancer Center, Boston, Massachusetts, United States of America.
4
Department of Surgical Oncology and Genomic Medicine, University of Texas, M.D.Anderson Cancer Center, Houston, Texas, United States of America.
5
Harvard Medical School, Boston, Massachusetts, United States of America; Division of Medical Oncology, Massachusetts General Hospital Cancer Center, Boston, Massachusetts, United States of America.
6
Harvard Medical School, Boston, Massachusetts, United States of America; Division of Hematology Oncology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America.
7
Harvard Medical School, Boston, Massachusetts, United States of America; Department of Dermatology, Massachusetts General Hospital, Boston, Massachusetts, United States of America.

Abstract

While response rates to BRAF inhibitiors (BRAFi) are high, disease progression emerges quickly. One strategy to delay the onset of resistance is to target anti-apoptotic proteins such as BCL-2, known to be associated with a poor prognosis. We analyzed BCL-2 family member expression levels of 34 samples from 17 patients collected before and 10 to 14 days after treatment initiation with either vemurafenib or dabrafenib/trametinib combination. The observed changes in mRNA and protein levels with BRAFi treatment led us to hypothesize that combining BRAFi with a BCL-2 inhibitor (the BH3-mimetic navitoclax) would improve outcome. We tested this hypothesis in cell lines and in mice. Pretreatment mRNA levels of BCL-2 negatively correlated with maximal tumor regression. Early increases in mRNA levels were seen in BIM, BCL-XL, BID and BCL2-W, as were decreases in MCL-1 and BCL2A. No significant changes were observed with BCL-2. Using reverse phase protein array (RPPA), significant increases in protein levels were found in BIM and BID. No changes in mRNA or protein correlated with response. Concurrent BRAF (PLX4720) and BCL2 (navitoclax) inhibition synergistically reduced viability in BRAF mutant cell lines and correlated with down-modulation of MCL-1 and BIM induction after PLX4720 treatment. In xenograft models, navitoclax enhanced the efficacy of PLX4720. The combination of a selective BRAF inhibitor with a BH3-mimetic promises to be an important therapeutic strategy capable of enhancing the clinical efficacy of BRAF inhibition in many patients that might otherwise succumb quickly to de novo resistance. Trial registrations: ClinicalTrials.gov NCT01006980; ClinicalTrials.gov NCT01107418; ClinicalTrials.gov NCT01264380; ClinicalTrials.gov NCT01248936; ClinicalTrials.gov NCT00949702; ClinicalTrials.gov NCT01072175.

PMID:
24983357
PMCID:
PMC4077767
DOI:
10.1371/journal.pone.0101286
[Indexed for MEDLINE]
Free PMC Article

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