SIDEBAR: Progression-free Survival Curve for Regorafenib Hints at Subgroup Effect
In all likelihood, only a subset of patients given regorafenib derive benefit, as suggested by the progression-free survival curve seen in the CORRECT trial, according to Dr. Overman.
“This is a very interesting curve. The medians don’t really capture the difference.… If you look more at the area of separation between the two, that’s captured better with a hazard ratio—big difference,” he noted.
“This curve is … reminiscent of another curve that we’ve seen before. That other curve is related to the experience we have had with anti-EGFR antibodies. This is actually a curve pulled from panitumumab [Vectibix] vs best supportive care prior to any knowledge about KRAS. And this shape of the curve is a subset effect,” he explained, whereby patients with wild-type KRAS benefit, but patients with mutant KRAS do not.
“This is the same thing we are seeing with regorafenib—likely a population that is getting no benefit and a population that is getting benefit,” Dr. Overman asserted. “One of the problems we have right now is we have no way to determine what that population is. So that’s a very interesting area for us to explore and try to sort out.” ■
Key colorectal cancer studies presented at this year’s ASCO Annual Meeting are changing the treatment landscape in this disease, according to Michael Overman, MD, of The University of Texas MD Anderson Cancer Center, who reviewed the data at the Best of ASCO San Diego meeting. The mix included...
“Microsatellite instability status is a validated prognostic marker in stage II colorectal cancer. It is the strongest prognostic marker we have in that group,” Dr. Overman commented. “The fact is that we should be getting this [test] consistently to help us make this discussion [of prognosis]...