Thousands of cancer researchers are meeting at the American Association for Cancer Research (AACR) 2015 Annual Meeting where the first research abstracts highlighted to the media included experimental immunotherapy applications to three kinds of advanced cancers: melanoma, lung cancer, and virus-associated lymphoma and leukemia in patients receiving bone marrow transplants.
Johns Hopkins melanoma and immunotherapy expert Suzanne Topalian moderated the press briefing on Sunday, April 19.
First, Antoni Ribas from UCLA presented data comparing two different types of immunotherapy drugs for melanoma: one that blocks the PD-1 receptor (pembrolizumab) and the other that blocks CTLA-4 (ipilimumab). Ribas and his team found that response rates nearly tripled, and progression-free survival and overall survival both improved significantly in patients who received pembrolizumab compared with ipilimumab. According to Topalian, ipilimumab approval by the FDA in 2011 was a landmark point, signaling the first drug of any kind to show a survival advantage for patients with advanced melanoma in a randomized trial. "Ipilimumab is now the gold standard by which everything is measured," said Topalian. " With the new data, both Topalian and Ribas say a change in the treatment landscape for melanoma is happening.
Next, Edward Garon from UCLA presented data on another immunotherapy drug that targets PD-L1 proteins in a trial of lung cancer patients. The trial also evaluated a potential biomarker for response to the immunotherapy drug class. According to the research team, most of the patients receiving the immunotherapy drug had better outcomes than would be expected with standard therapies. But results of the biomarker to predict outcomes were less clear as the range of responses to the immunotherapy drug varied over the spectrum of biomarker levels in evaluated patients. Patients with more expression of the biomarker experienced more favorable outcomes than those who had lesser expression, but, according to Topalian, "even patients with lower expression [levels of the biomarker] have good outcomes." What does this mean for patients and clinicians? According to Garon, the pursuit for more biomarkers, particularly those that can predict the level of response, continues.
Finally, Richard O'Reilly from Memorial Sloan Kettering Cancer Center presented data that demonstrates, according to Topalian, "the power of T-lymphocytes to eradicate cancer." O'Reilly and his team conducted a clinical trial to test a new immune-based treatment to treat a lethal complication of bone marrow transplantation called Epstein-Barr virus-associated lymphoproliferative disorder. The research team created a bank of immune system cells called T cells, taken from the blood of individuals without cancer, which responded to proteins associated with the Epstein-Barr virus. In patients experiencing the BMT-related complication, the research team compared this type of "banked" treatment taken from third-party healthy individuals with a similar type of T-cell treatment created from each patient's donor T cells. O'Reilly said that outcomes of transplants were similar using the T cell treatment from both third-party "banked" and transplant donor sources. The advantage, he said, is that banked treatments are immediately available to patients in need of rapid therapy.
Also included in a news briefing for the media was a preliminary human study of immunotherapy in triple-negative breast cancer, presented by Johns Hopkins Kimmel Cancer Center oncologist Leisha Emens. Emens said results show the immune-based therapy is "generally safe and well tolerated" in women with metastatic, triple-negative breast cancer, a persistently difficult form of the disease to treat.