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kill tumor cells while sparing healthy ones. Celldex CEO Anthony Marucci estimates that about 3,000 patients in the U.S., and 6,000 in Europe, have glioblastoma with an EGFRvIII mutation. The cancer recurs for most of them.
“Targeted therapy has been very successful in melanoma, in breast cancer, in a lot of the leukemias and lymphomas, where the actual mutations are being targeted,” O’Rourke says. If it were to end up getting approved, “to my knowledge, this would be the first approval of a targeted therapy [in glioblastoma] where the goal of the therapy is to induce an immune response against a specific mutation in the tumor.”
Celldex’s vaccine has a fairly long history. The company, which was spun out of Medarex (now owned by Bristol-Myers Squibb) several years ago, cut a deal with Pfizer in 2008 to co-develop it. Pfizer bailed on rindo (then known as CDX-110) two years later, sending Celldex shares spiraling downward, but the company has continued its development. Rindo is the furthest along of a group of immuno-oncology drugs Celldex is trying to advance.
Celldex aims to position the vaccine both as a front-line treatment, in combination with temozolomide, and for patients who relapse. A phase 3 trial testing rindo for newly-diagnosed brain cancer patients is expected to produce interim data in mid-2015. Celldex decided to try testing the vaccine in people who’ve relapsed after temozolomide therapy only after some patients who weren’t eligible for its studies but received the treatment under a “compassionate use” program—sicker patients, whose tumors had continued to grow despite radiation and chemotherapy—appeared to have some benefits. The idea was to see if rindo could be used on even the sickest of glioblastoma patients: those who were just about to go on bevacizumab, and those who hadn’t responded to it.
“We looked at this study as a challenge,” Davis says.
This is also the first rindo study Celldex has reported data from with a control arm. The other mid-stage trials it ran, in newly-diagnosed glioblastoma patients, were all single-arm trials comparing survival figures to “historical” control groups.
In this trial, Celldex divided patients into a few groups. The first group of 72 patients hadn’t taken bevacizumab yet. They were randomized, to receive either rindo and bevacizumab, or bevacizumab alone. Celldex then enrolled 25 patients into a second arm to see how the drug would fare in patients whose disease had progressed despite treatment with bevacizumab, where there are no approved therapies. After seeing a couple of responses in that group to treatment last year, Celldex added another 28 patients into it, with the idea of deciding whether or not to continue developing the drug there if the data looked good.
Celldex saw what it was hoping to see for patients who hadn’t taken bevacizumab. But for the sicker patients—those whose cancer progressed despite treatment—it didn’t. Though there were some signs of activity in those patients, Davis says Celldex hasn’t seen any additional responses in that group since the first few it reported last year, so it’s going to focus on other stages of brain cancer progression.
“Realistically, knowing that we’ll have data from other studies and have pretty good data in [patients who hadn’t taken bevacizumab yet], it doesn’t really make sense for us to expand [the other group] at this point anyway,” he says.
If the data for the other patient groups hold up, and Celldex can continue to show a benefit, it would be bucking a trend. There is a long list of cancer vaccines that have flopped in clinical trials, among them GlaxoSmithKline’s MAGE-A3, and Merck KGaA’s Stimuvax. While Celldex still has a long way to go, it’s taken one step closer than most.