Tomorrow the American Society of Clinical Oncology* will host its 9th annual GI Cancers Symposium. Bloomberg and the LA Times have already reported findings of a paper, still in abstract form, to be presented on Saturday.
The drug of interest is regorafenib, a pill that loosely inhibits quite a few kinases – enzymes critical in cell signals that control growth of normal cells, tumors and blood vessels. The experimental med, manufactured by Bayer, is also known as BAY 73-4506. The new data emerge from an international, randomized Phase III trial that goes by a loaded acronym: CORRECT.
The study included 760 patients with advanced colon or rectal cancer whose tumor progressed after receiving standard treatments. Participants received either the study drug or BSC (best supportive care) and a placebo. According to the paper, BSC includes antibiotics, pain meds, radiation for bone mets, steroids and some other treatments. The median survival in patients who received the Regorafenib was 6.4 months, compared with 5.0 months in patients who got the placebo. This difference, of 1.4 months in the median, was statistically significant. The “disease control rate” – a term that warrants separate explanation – was 44% in the regorafenib group c/w 15% in the placebo group.
The most frequent high-grade toxicities reported so far include a skin reaction affecting patients’ hands and feet, fatigue, diarrhea, elevated bilirubin in the blood, and high blood pressure. (Question to ask the oncologist who’s presenting these data at the meeting – was the elevated bilirubin from liver damage or hemolysis? With all the $millions spent on this trial, surely someone’s followed up on that detail.)
The language of the report and investigators’ comments are reminiscent of some regarding Avastin for advanced breast cancer. According to a media release: “…a subset of patients in the trial have responded particularly well to regorafenib, continuing to have stable disease for a relatively long time; research is ongoing to find ways to identify these individuals.” There are no biomarkers known to check for Regorafenib responsiveness.
What’s odd is that, according to the abstract, # LBA385, all patients entered the study between May, 2010 and March, 2011. This means some subjects were evaluated for less than a year, and the longest observation period for any patient on the trial is 20 months. Seems early to draw meaningful conclusions about the long-term toxicity and possible benefits of a cancer drug, especially for tumor types, like colorectal cancer, that don’t generally grow fast (c/w a condition like acute leukemia).
The list of investigators’ disclosures regarding ties to industry is too long to post here. You can find them at the tail end of the release. The FDA has assigned Fast Track status to this drug, according to Bayer.
*I am an ASCO member.