A new class of anti-cancer drugs that allow the immune system to attack cancer cells are generating considerable excitement among patients, doctors, and investors. New results being released ahead of the annual meeting of the American Society of Clinical Oncology (ASCO) are likely to feed that fervor.
ASCO holds its meeting at the end of the month, but releases abstracts on most of its studies this evening. In addition, ASCO held a press briefing earlier today under the requirement that reporters hold their stories until the abstracts went live.
On the press call, Jedd Wolchock of Memorial Sloan-Kettering Medical Center in New York presented data showing that nivolumab, an experimental drug being developed by
Nivolumab works by blocking the programmed death receptor 1 (PD-1), a cell receptor on immune cells that is involved in preventing them from consuming other cells. Turning it off leads the immune cells to eat the cancer.
The combination is potentially important because
In previous studies, patients with advanced metastatic melanoma have had an objective response rate (ORR, a measure of tumor shrinkage) of 11% when treated with Yervoy and 41% when treated with nivolumab. The combination also had a 40% ORR in the 53 patients treated. But in 16 of those patients, or 31%, there was a reduction in the size of their tumors of more than 80% in 12 weeks, a sign that the combination might have profound long-term effects for some patients.
ASCO President Sandra M. Swain said that this “rapid and profound lasting tumor shrinkage kind of response has not been seen with immunotherapies before.”
Bristol shares rose 5% today ahead of the release of the data. “One hypothesis is that somebody in the press may have leaked the data,” said Mark Schoenebaum, a sell-side analyst at ISI Group, on a webcast with clients. Bristol said it could not comment on market movement. “We have not had any indication that an ASCO embargo has been broken or any news has been released in advance of the 6pm public posting of ASCO’s abstracts,” an ASCO spokeswoman said.
Roche also presented data on its similar drug. Instead of targeting PD-1, which is on the immune system cell, it blocks another cell receptor called PDL-1 that is found on tumor cells. The idea is that this may be safer, because it won’t lead to other immune system related side effects. But Bristol had its own PDL-1 drug in cancer development, and dropped it.
Nevertheless, the Roche results, also in advanced melanoma, look promising. Twenty-nine of 140 patients, or 21%, had an ORR. For those whose tumors tested positive for PD-L1 (Roche is also developing a diagnostic) that jumped to 36% (that’s 13 of 36). Interestingly, even when the PD-L1 receptor wasn’t there, 13% had an ORR. (That’s 9 patients out of 67.)
Merck’s PD-1 drug wasn’t part of the press program, but the company will be presenting data on it at ASCO. It looks very similar to Bristol’s: the key question is whether Merck is behind, and whether it can catch up either in melanoma or in other diseases where these drugs show promise. The company is also conducting trials in non-small cell lung cancer, head and neck cancer, metastatic bladder cancer, and triple negative breast cancer, a form of the disease that does not respond well to other medicines.
Gary Gilliland, the Merck senior vice president in charge of the company’s oncology research, told me that he views Merck as “contemporaneous” with Bristol in the PD-1 race. But he also said that this should not be viewed as a horserace. “All we’re trying to do is to move as quickly and rapidly as possible,” Gilliland said.
ISI’s Schoenebaum noted in his webcast that Merck has a big 500 patient melanoma trial that is set to end in 2015, but speculates that it could potentially yield some data as early as 2014. That’s when Bristol is expected by analysts to file for approval.
Another promising drug presented in the press program: Idelalisib from
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