Phase II study of Sorafenib (BAY 43–9006) in hormone-refractory patients with prostate cancer: A study of the Central European Society for Anticancer Drug Research—EWIV (CESAR)

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Background: Sorafenib (BAY 43–9006) is a novel, orally active multi-kinase inhibitor with anti-angiogenic and anti-proliferative activity, blocking both Raf/MEK/ERK pathway and receptor tyrosine kinases VEGFR-2 and PDGFR. Activity of sorafenib in hormone-refractory progressive patients (pts) with prostate cancer (PC) was investigated in a Phase II clinical study. Methods: Pts received sorafenib 400 mg bid by continuous oral dosing. Pts with progressive disease during hormonal treatment and no prior chemotherapy therapy for advanced prostate cancer, and either one uni-dimensional measurable lesion according to RECIST-criteria or increasing PSA values reflecting a hormone-refractory situation, were eligible for study entry. Tumor PSA-based response was defined as: increase of PSA from baseline or lowest measured value by 100% = progressive disease (PD); decrease of PSA by >50% in two consecutive measurements = responder; PSA levels in between the two definitions above = stable disease (SD). Primary study objective was the proportion of patients with time to progression of ≥12 weeks (PP-TTP-12) using target lesions and PSA based response evaluation. At least 45 evaluable pts were required to detect an increase in PP-TTP-12 from 20 to 40% in a one stage design. Secondary endpoints were overall response and survival, and toxicity according to Common Toxicity Criteria (CTC v3.0). Results: A total of 55 pts with PC were enrolled between October 2004 and June 2005. The majority of pts (40/55, 72.7%) were treated for at least 6 weeks. Among the 42 pts evaluable for PP-TTP-12, 2 pts (4.8%) had a response and 15 pts (35.7 %) showed SD ≥12 weeks and 25 pts (59.5 %) showed PD. The one-sided binomial test of the null-hypthesis of PP-TTP-12 = 20% can be rejected at a significance level of 5% (p= 0.0019). All 55 pts were included in the evaluation of adverse events. Drug-related serious adverse events (diarrhea (1), constipation (1), fatigue (1), skin (1) cardiac (2) were seen in six patients. Conclusions: These results of a PSA-based evaluation indicate that sorafenib has some clinically useful activity in PC. Further investigations are necessary to evaluate the clinical benefit. Final results will be presented.

No significant financial relationships to disclose.