Intermittent chemo feasible in advanced prostate cancer

September 1, 2006

Atlanta-Like intermittent androgen deprivation, could intermittent chemotherapy give men with prostate cancer welcome treatment holidays and still control cancer?

Tomasz M. Beer, MD, thinks that it could for some men, based on data from the multicenter Androgen-Independent Prostate Cancer Study of Calcitriol Enhancing Taxotere (ASCENT) trial that compared docetaxel (Taxotere) alone with the combination of docetaxel and DN-101, a high-dose formulation of calcitriol (vitamin D).

"At the present time, we've not defined what to recommend to those patients beyond chemotherapy," said Dr. Beer, associate professor of medicine, division of hematology and medical oncology, Oregon Health Sciences University Cancer Institute, Portland. "Indefinite chemo is not very practical because of toxicity."

Those who were eligible for the intermittent therapy were not representative of the entire patient population, Dr. Beer pointed out. Although they were similar in age and in the number of metastatic sites, they had better performance status, less measurable disease, and lower PSA, higher hemoglobin, and lower serum alkaline phosphatase levels before they started chemotherapy. Patients could choose to suspend treatment if they had a confirmed reduction in PSA of 50% or more and serum PSA of 4.0 ng/mL or less.

After completing the first cycle of chemotherapy, these men were followed up with serum PSA every 4 weeks; those with measurable disease underwent computed tomography scans every 8 weeks. Chemotherapy was resumed when patients' PSA increased by ≤50% and was≤2.0 ng/mL or if other evidence of cancer progression was detected.

Patient response after break

Of 45 patients, 38 completed the first treatment holiday. Of those, 36 have been re-treated, and data are available on 34 of them. Seven patients remain on a treatment holiday. Mean duration of the first chemotherapy holiday was 17 weeks, with 42% of men having a treatment hiatus of 20 weeks or longer. The treatment holiday ranged from 4 to 71 weeks "and counting," Dr. Beer said.

After the first chemotherapy holiday, 56% of patients responded with a 50% or better reduction in serum PSA from the post-holiday baseline, and 21% met the criteria for stable PSA for at least 12 weeks, whereas 24% resumed chemotherapy. The DN-101 and placebo groups were not compared because of lack of power to do so.