Immunotherapies in Clinical Trials: Do They Demand Different Evaluation Tools?

Extract

Melanoma patients and immunotherapy researchers alike had cause to celebrate in late March when the U.S. Food and Drug Administration approved ipilimumab (Yervoy) to treat metastatic melanoma. For patients, the drug is a much-needed alternative to the commonly used dacarbazine (DTIC-Dome), the first agent shown to prolong overall survival. For immunotherapy researchers, the drug, which works by binding to a receptor on the surface of T lymphocytes and releasing the brakes on the immune system, represents one more piece of evidence that they can recruit a patient's immune system to fight cancer.

Despite ipilimumab's success, a key question in the field remains how best to measure disease response in patients treated with immunotherapies. No one will argue with the statistically significant increase in overall survival that occurred in the pivotal ipilimumab trial (10 months in patients treated with ipilimumab with or without an experimental vaccine vs. 6.5 months for patients treated with the experimental vaccine alone). However, many researchers are concerned that response and progression-free survival criteria developed in the era of cytotoxic therapies are inappropriate measures for immunotherapeutic agents and may lead to premature closures of trials and, perhaps, loss of active therapies.