work quickly for some patients, but not all who responded. Some patients had a “delayed response” in which their tumors first appeared to spread, and then shrink later, as if it took a while for the immunotherapy boost to kick in. Researchers don’t know why some patients responded quickly and others had the delay.
—Patients whose tumors shrank appeared to have long-lasting remissions. Scientists said 26 of the 29 who responded saw their tumors remain in check for long periods of time, between three and 15 months of follow-up. As time goes on, researchers will gather more complete statistics on how long-lasting the responses really are.
—Side effects of the treatment weren’t trivial, and they were consistent with what researchers have seen with Bristol-Myers’ ipilimumab. About 39 percent of patients had moderate to severe side effects, including toxicities to the liver (hepatitis), the skin (rash), and the gut (colitis).
—Genentech, through working internally with Roche diagnostic colleagues, is seeking to develop a companion diagnostic that can help doctors sort out which patients are most likely to respond to the immunotherapy. In this study, Genentech asked whether patients were overexpressing the PD-L1 target on their tumors, and whether that made them more likely to respond. The answer wasn’t clear-cut. Researchers saw that 13 of 33 patients deemed to be PD-L1 overexpressers (39 percent) responded to the anti-PD-L1 antibody, while 8 of 61 patients (13 percent) who were classified as having PD-L1 “negative” tumors ended up responding to the drug. More research is being done to develop the diagnostic test and study the way the drug is working, Bowden says.
Like with all immunotherapies, there was quite a bit of variability in responses, which researchers still don’t understand well. The patients were heavily pre-treated, and many had weakened immune systems, which didn’t appear to stop them from responding to the immunotherapy, Bowden said.
Based on the data Genentech has gathered thus far, the company has decided to forge ahead into the third and final phase of clinical trials required for FDA approval—the kind of studies which take the most time and money, and which generate the most thorough datasets. Genentech is going ahead to that phase in lung cancer and kidney cancer, Bowden said. A mid-stage study is currently enrolling 100 patients with non-small cell lung cancer on the new immunotherapy, according to a posting on clinicaltrials.gov.
This year at ASCO, Bowden said he’ll be watching several other companies make presentations about their various immunotherapies in the works. The progress of this new mode of therapy is likely to be one of the big stories to watch at the big convention this year.
“The story continues to build,” Bowden said. “We’re going to start seeing more data, and people are going to start talking about combinations and how you can move the needle even further. If you talk to oncologists in general, immunotherapy is now in their oncologist’s lexicon. They understand it. The science is moving forward.”
