The researchers divided the patients into three groups of five; each group received two doses of either 1x109, 3.3x109 or 1x1010 units of Listeria at three-week intervals. They administered ampicillin five days after each dose, first intravenously and then orally for 10 days.
Each patient developed flu-like symptoms, including fever, chills and nausea with or without vomiting. In the lower doses, these symptoms were treated with non-prescription non-steroidal anti-inflammatory drugs (NSAIDs) and anti-emetics. Patients in the highest dose group had the same but more severe symptoms.
Rothman used the RECIST criteria to assess the tumors in 13 patients. At the end of the study, five patients had progression of their cancer, seven were stable, and one patient showed a partial response to the therapy. Three of the seven stable patients had tumor reductions of about 20 percent.
The partial response patient who was stage IVb at trial initiation was given six chemotherapy courses and a radical hysterectomy. Currently, she is tumor- free and her blood tests are normal. Six of the 13 patients are surviving, with a median survival of 424 days. Median survival for all 15 treated patients is 327 days.
CTLA-4 blockade for hormone refractory prostate cancer: dose-dependent induction of CD8+ T cell activation and clinical responses: Abstract 2539
Blocking CTLA-4, a cellular molecule on lymphocytes that inhibits immune response, produced meaningful clinical benefits in patients with prostate cancer that hadnt responded to hormone therapy, according to researchers.
CTLA-4 blockade works by removing the brakes on the immune system. Our results show that enhancing immune responses in prostate cancer patients can lead to clinical responses, said Lawrence Fong, M.D., a hematology/oncology research
|Contact: Staci Vernick Goldberg|
American Association for Cancer Research