Sometimes when a drug hits the market, it can take on a life of its own. Researchers start using their imaginations—and their own grant money—to pursue applications the drugmaker itself might never have envisioned. And sometimes, those researchers make important new discoveries, which can provide the company with a running start on a potentially lucrative opportunity.
One of those stories is happening now at Seattle Genetics.
The Bothell, WA-based cancer drug developer (NASDAQ: SGEN) said this month that it is pushing ahead with the final stage of clinical trials to test its brentuximab vedotin (Adcetris) for patients with cutaneous T-cell lymphoma (CTCL). The company agreed to invest in the 124-patient study after seeing that researchers, operating independently at MD Anderson Cancer Center and Stanford University, both ran trials suggesting the Seattle Genetics drug could be an important new advance for CTCL. If the company and its partner, Cambridge, MA-based Millennium Pharmaceuticals, can confirm what the researchers saw in those smaller trials, then it could pave the way to an FDA approval of the drug for a third type of lymphoma. That could open the door to treating another 1,000 new patients a year in the U.S., expanding the number of people eligible to get the drug by about 35 percent.
Cutaneous T-cell lymphoma comes in a lot of different forms, and although it doesn’t usually kill people, it is painful and disfiguring. It’s a disease in which cancerous immune system cells migrate to the skin, causing nasty lesions. There are a few treatments out there, such as topical immune suppressors, radiation, or chemotherapy. There are also more targeted drugs like Eisai Pharmaceuticals’ bexarotene (Targretin), Merck’s vorinostat (Zolinza), or Celgene’s romidepsin (Istodax). But once patients progress past the early rounds of therapy, no treatments have shown tumor shrinkage rates beyond about 35 percent, much less an ability to spur long-term remissions. The Seattle Genetics drug, in the hands of the Stanford and MD Anderson researchers, boosted the response rate up to more than 65 percent, and in one study showed the remissions lasted at least six months and counting. That’s the kind of data that prompted Seattle Genetics to make CTCL one of its more promising new corporate R&D priorities.
“We’ve talked to the doctors extensively, and we are thrilled with the activity they are seeing,” says Seattle Genetics CEO Clay Siegall. “This is the most active drug in CTCL they’ve ever seen.”
Seattle Genetics won FDA approval for brentuximab vedotin back in August, originally as a treatment for relapsed forms of Hodgkin’s lymphoma and anaplastic large cell lymphoma (ALCL). But for years, the company has seen those two conditions as just a starting point. The drug is designed to hit a marker known as CD30 on the surface of cells. Hodgkin’s and ALCL are known to carry the CD30 marker, so there was a good scientific rationale to try the drug first on those patients.
What was less clear to Seattle Genetics, or anybody else, was just how many other cancers have CD30 markers on them, or how prevalent the CD30 markers need to be for the new drug to make a difference. Basically, once Seattle Genetics proved that it had a hammer for CD30, scientists suddenly started looking more aggressively for that nail. Published literature says about half of CTCL patients have tumors expressing the CD30 marker, which made it appear worth exploring, but not necessarily a slam dunk for Adcetris to show anti-tumor activity. “We spent time looking, but the literature was kind of sketchy,” Siegall says. “Before Adcetris was approved, nobody cared that much about CD30.”
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