Immunotherapy-Chemo Combo Possible
Data suggests this approach may prolong life in men with androgen-independent prostate cancer
Daniel Petrylak, MD, explained that immunotherapy and chemotherapy have been considered to be an-tagonistic and thus should not be combined when treating AIPC. Preclinical evidence, however, suggests that the modalities can be safely and effectively combined, said Dr. Petrylak, associate professor of medicine and director of genitourinary oncology at Columbia Pres- byterian
Dr. Petrylak presented pooled data on 212 men with asymptomatic AIPC enrolled in two randomized, controlled trials. Patients received an infusion of either sipuleucel-T or placebo every two weeks for a total of three infusions. If disease progressed, patients in the sipuleucel-T arm were treated according to physician preference; 37% received docetaxel. Patients who progressed in the placebo arm received sal-vage therapy with a different preparation of sipuleucel-T consisting of frozen dendritic cells every two weeks for a total of three treatments; 41% received docetaxel.
Patients treated with sipuleucel-T first had a survival advantage of a median of 4.3 months com-
pared with placebo. At 36 months, 36% of patients treated with sipuleucel-T were alive versus 15% in the placebo arm. The immunotherapy was generally well tolerated. The most common adverse events were low grade and transient, lasting one or two days following infusion. They included rigors, fever, headache, fatigue, dyspnea, vomiting, and tremor.
Therapeutic sequence unclear
It is unclear whether sipuleucel-T or docetaxel should be given first or if the two agents should be given intermittently, Dr. Petrylak said. This issue is of particular importance for asymptomatic patients, who often prefer to wait as long as possible to be treated.
In Dr. Petrylak's view, evidence from these randomized trials suggests that the optimal sequence would be to give sipuleucel-T first, followed by chemotherapy. This is because the immune system remains activated three to six months following treatment with sipuleucel-T, and
a sustained immune response could potentially interact with subsequent chemotherapy, which is what appears to have occurred in the two randomized trials.
Median survival in patients who received docetaxel was 34.5 months in the sipuleucel-T arm (14 months longer than predicted by Halabi nomogram) versus 25.4 months in the placebo arm.