new opportunities this trial might unearth for Adcetris. It could be that 5 percent of ovarian cancer patients have abundant CD30 counts that make them prime candidates, or maybe it will be 5-10 percent of pancreatic cancer patients. As Siegall and Reynolds acknowledged, this study is more about helping Seattle Genetics and researchers form hypotheses about where to test Adcetris in the future than it is about gathering bulletproof evidence in favor of the drug. That kind of hard data will have to come in more precisely goal-oriented follow-up trials. But David Miller, president of Biotech Stock Research in Seattle, said this approach could provide a strong rationale for future clinical trials, and those studies could be attractive because they are likely to be shorter, less risky, and cheaper than investors are accustomed to.
What it amounts to is that the FDA might be willing to allow Seattle Genetics to get additional uses for Adcetris approved for certain CD30-positive patient groups, on the basis of testing just 100 or so patients, as long as it can show two-thirds or more of them are going to respond to therapy, and it’s paired with a companion diagnostic. Many of today’s cancer trials—in which companies can’t precisely predict who will or won’t respond to the drug—are forced to enroll many more patients in order to capture a relatively small percentage who will benefit.
Besides changing the financial equation for drug development, these new uses of Adcetris could change the math for insurers as well. Suddenly an expensive drug like this one—which costs $13,500 for an every-third-week infusion—doesn’t look as expensive when it’s only going to be used by precisely identified niche of patients who are 60-80 percent likely to benefit.
Like any clinical trial, there are plenty of risks. Patients on the Seattle Genetics drug have been diagnosed with PML, a rare and potentially deadly brain infection, and it could be a warning sign if a disproportionate number of those turn up. And while Adcetris looks like a potent hammer against CD30, it’s possible that it won’t be as effective in hitting that target on solid tumors, which can be more difficult for antibody drugs like Adcetris to penetrate, as compared to blood-based liquid tumors. Those are questions that would have to be answered in subsequent trials. But the odds of an anti-CD30 antibody working in people who overexpress the CD30 receptor on their tumors are bound to be high.
“This isn’t like throwing the spaghetti up against the wall and seeing what sticks,” Miller says. “I’m very hopeful they will find additional indications that can expand the (FDA-approved) label. If they can, it will be good for the industry, not just good for the company.”
