CHICAGO--Now that we know that a single immunotherapy can slow cancer, it stands to reason that two can do better. And that's what investigators say happened when they combined Sanofi's ($SNY) white blood cell booster GM-CSF with Bristol-Myers Squibb's ($BMY) Yervoy.
After a year of treatment, investigators say that more than two-thirds of the melanoma patients on the combo regimen were still alive, versus half of those receiving Yervoy alone. Both agents spur an immune response but take different approaches. Yervoy targets CTLA-4, which keeps T cells in neutral, while GM-CSF is a nonspecific immunotherapy that boosts white blood cell levels. It's commonly used to help bolster cancer patients after chemotherapy.
Investigators knew full well that Yervoy could work on melanoma. It was approved in 2011. "The main question," Dana-Farber's Stephen Hodi told an audience at ASCO on Saturday, "was how to improve on these results."
A total of 245 patients with metastatic melanoma were recruited for the study, with 68.9% of the patients in the combo arm alive after a year. Exactly 52.9% in the Yervoy monotherapy arm were alive at the same point. There was no significant difference in tumor shrinkage, but the combo arm enjoyed a 35% reduction in the risk of death.
"The result of the E1608 study provided another important sign that immunotherapy can have a big impact for patients with advanced melanoma," says Hodi. "At the same time, we still need to clarify the best way to apply these findings in everyday practice."
Immunotherapy is the key theme at ASCO this year, and this study of two approved immunotherapies in combination highlights the potential for a full range of combination studies that match experimental and approved treatments. Look for many more such studies in the years to come.