Summary
The new drug PLX-4032, being developed by Plexxikon and Roche, continues to show impressive short term results in melanoma patients with specific BRAF mutations, with a reported 70% tumor response rate.
Analysis
In this most recent presentation, given at the annual European Oncology (ECCO) meeting in Berlin, updated Phase I data showed partial responses (by RECIST criteria, more than 30% tumor shrinkage) in 17 of 27 patients, and complete responses (complete disappearance of tumor) in 2/27 patients, for an overall response rate of 19/27 or 70%. An additional 5/27 patients showed some tumor shrinkage, not quite enough to rate as a partial response. Only patients with mutations in the BRAF cellular proliferation gene show responses; wild-type BRAF melanomas have not responded to this drug.
Currently, a Phase II trial with about a dozen sites has begun, with stated plans to open up a Phase III trial, comparing PLX-4032 to standard chemotherapy with Dacarbazine (DTIC) by early 2010.
These results are an extension of earlier reported (and analyzed) data. Still unclear are the long term effects of this drug. Is there a prolonged progression free interval? Will this high response rate result in a survival benefit? Are there any longer term significant toxicities, particularly in light of the findings of non-melanoma skin cancers in about 1/4 of treated patients?
Eric Whitman consults with leading institutions through GLG
Analyses are solely the work of the authors and have not been edited or endorsed by GLG.
