Provenge: Lessons Learned
Last week’s FDA approval of Provenge, the therapeutic prostate cancer vaccine, was a win for Dendreon, but also is a boon for companies involved in developing cancer immunotherapies. This morning at BIO, I spoke to Jens Oliver Funk, senior vice president, Merck Serono R&D, and global head of oncology for the company, about what it might mean for other immunotherapeutics in the pipeline.
“This is great news and will change the field,” Funk said. “Until last Thursday, people said therapeutic vaccines could work. Now, they can say the therapeutic principle has been validated.”
For its part, Merck Serono is trying to push Stimuvax, a cancer vaccine that has hit a few road blocks during mid-stage trials, to the finish line.
However, Funk cautioned that despite Dendreon’s success, there is still a long way to go towards making immunotherapies that are effective and viable in large patient populations. Provenge “is still a very laborsome, highly individualized therapy,” he noted. Now, companies need to build on the groundwork laid by Dendreon and evolve the science to make vaccines that are more effective and easier to make.
Funk cited several key lessons learned from Provenge’s long road to FDA approval. First, it has become clear that clinical trials for therapeutic cancer vaccines need to be structured differently than studies for traditional drugs, like chemotherapies. “Historically, late-stage tumor patients were included in such studies, and we now know we need patients earlier on, when they have little tumor mass.”
Second, in order to optimize an immunotherapy’s activity, companies need to pick patient populations carefully. You need to create “an environment in patients’ bodies for fostering T-cells,” Funk explained. Chemotherapy depletes the very T-cells that immunotherapies are trying to stimulate, meaning patients that have just undergone an intensive round of chemo aren’t primed to respond to the vaccines.
Last, companies and regulatory authorities will need to reconsider the endpoints in clinical trials. Traditional cancer drug trials look at how quickly and by how much a tumor is shrinking, but its possible that a therapeutic vaccine can extend patients’ lives without ever actually reducing tumor mass.
For anyone at BIO, run over to room S403b, where a panel discussion on cancer immunotherapies moderated by Funk is going on now!