The definition of progression on vemurafenib (zelboraf) has a definition in clinical trials but does not necessarily have the same one in clinical practice. The issue of how much disease progression to “tolerate” before discontinuing vemurafenib is a difficult issue as many patients were treated beyond the first evidence of progression even in the clinical trials and some patients fared well thereafter. Much of the decision is influenced by the issue of whether there are other therapies to pursue (in other words, whether the patient has received ipilimumab previously or not). Similarly, the availability of a compelling clinical trial influenced the decision with regard to how quickly one considers discontinuing vemurafenib in the face of disease progression.
See more about our Scientific Board member Keith Flaherty at: http://www.massgeneral.org/cancer/news/multimedia.aspx?id=618