Journal
CLINICAL CANCER RESEARCH
Volume 14, Issue 24, Pages 8302-8307Publisher
AMER ASSOC CANCER RESEARCH
DOI: 10.1158/1078-0432.CCR-08-1002
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Funding
- National Cancer Institute [NO1-CM-17105, NO1 NCI-SAIC-Fredrick 24XS097-01, CA112899-01, R21 CA109388]
- Sergei S. Zlinkobb Fund for Medical Education
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Purpose: Activation of the mitogen-activated protein kinase (MAPK) pathway and the phosphatidylinositol 3-kinase/AKT pathway seems to be critical for melanoma proliferation. Components of these pathways are client proteins of heat-shock protein 90 (hsp90), suggesting that inhibition of hsp90 could have significant antimelanoma effects. We conducted a phase II trial using the hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) in melanoma patients. The primary end points were clinical responses and whether treatment inhibited MAPK pathway activity. Experimental Design: Melanoma patients with measurable disease were stratified on the basis of whether or not their tumor harbored a V600E BRAF mutation. The hsp90 inhibitor 17-AAG was administered i.v. once weekly x6 weeks at 450 mg/m(2). Tumor biopsies were obtained pretreatment and 18 to 50 hours after the first dose of 17-AAG, and were snap-frozen. Results: Fifteen evaluable patients were treated; nine had BRAF mutations and six were wild-type. No objective responses were observed. Western blot analysis of tumor biopsies showed an increase in hsp70 and a decrease in cyclin D1 expression in the posttreatment biopsies but no significant effect on RAF kinases or phospho - extracellular signal-regulated kinase expression. Plasma analyzed by mutant-specific PCR for V600E BRAF showed 86% sensitivity and 67% specificity in predicting tumor DNA sequencing results. Conclusions: At this dose and schedule of 17-AAG, the effects of 17-AAG on RAF kinase expression were short-lived, and no objective antimelanoma responses were seen. Future trials in melanoma should focus on a more potent hsp90 inhibitor or a formulation that can be administered chronically for a more prolonged suppression of the MAPK pathway.
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