Combination therapy increases PSA doubling time in prostate cancer patients

A combination of sipuleucel-T (Provenge) active cellular immunotherapy for prostate cancer and bevacizumab (Avastin) significantly increased the PSA doubling time in patients with prostate cancer who had relapsed after prior surgical and radiation therapy, according to recently published data from the Cleveland Clinic Taussig Cancer Center and the University of California, San Francisco.

The phase II, 22-patient, single-arm trial followed patients with androgen-dependent prostate cancer whose cancer had relapsed following surgical or radiation therapy. Sipuleucel-T was given intravenously at the beginning of the study and again on weeks 2 and 4, followed by bevacizumab, 10 mg/kg, also given intravenously. Treatment with bevacizumab was repeated every 2 weeks until disease progression was reported or until toxicity became unacceptable.

The team found that the combination extended PSA doubling time in the 21 evaluable patients by more than 85%, from 6.9 months before treatment to 12.7 months after treatment (p=.01). In addition, 29% of patients had a more than 200% increase in their PSA doubling time after combination therapy. Furthermore, the therapy led to PSA reductions in nine of 21 evaluable patients, including one patient with a PSA reduction of more than 50% and three patients with PSA reductions of more than 25%.

“These findings support our hypothesis that Provenge may have a significant impact on the progression of patients with recurrent disease after definitive local therapy,” said Mark Frohlich, MD, of Dendreon Corp.

The study appears in the online edition of Cancer (May 30, 2006).