Chemotherapy for the treatment of hormone-refractory prostate cancer

AIMS

This review aims at analysing the published literature on chemotherapy for hormone-refractory prostate cancer (HRPC) to provide recommendations for the treatment of this important patient group.

METHODS

The information for this review was compiled using the PubMed and Medline databases and the Proceedings of the American Society of Clinical Oncology annual meetings to search for articles, abstracts and presentations up to 1 March 2007. Electronic early-release publications were also included. Only articles published in English were considered. The search terms included hormone-refractory prostate cancer, docetaxel, mitoxantrone, satraplatin, ixabepilone, cyclophosphamide, vinorelbine, atrasentan, calcitriol, bevacizumab and targeted therapies. Priority was given to studies in high impact factor journals when available.

RESULTS AND CONCLUSION

Two recent trials (TAX 327 and SWOG 9916) have shown that docetaxel chemotherapy can significantly improve survival for HRPC. Docetaxel has become the standard of care for first-line chemotherapy for HRPC and has been approved for use in the United States and Europe. Many patients with HRPC will require second- and even third-line treatment upon progression and more data are required in this setting. It is likely that the future management of patients with HRPC will build on the success of docetaxel using a sequence of chemotherapy and targeted therapies to reduce the risk of death, prevent or improve disease-related symptoms and improve quality of life for this important condition.

Achieving Treatment Goals for Hormone‐Refractory Prostate Cancer with Chemotherapy

The belief that hormone-refractory prostate cancer (HRPC) is a chemotherapy-resistant disease has been effectively refuted by the results of two recent randomized phase III trials. The TAX327 trial compared weekly docetaxel, every-3-weeks (Q3W) docetaxel, and Q3W mitoxantrone plus prednisone in 1,006 patients with HRPC, and results demonstrated that survival was significantly longer with a docetaxel-based regimen than with mitoxantrone. That trial demonstrated that only Q3W docetaxel was significantly superior to mitoxantrone with respect to overall survival. Quality of life was also superior in the docetaxel groups. In the Southwest Oncology Group (SWOG) 9916 trial, 674 men with progressive HRPC were randomized to 3-week cycles of docetaxel plus estramustine or mitoxantrone plus prednisone. Overall and disease-free survival times were significantly longer in the docetaxel arm. Collectively, the results of these trials demonstrate that survival can be significantly improved with chemotherapy in patients with HRPC to an extent that is comparable with the survival benefits seen in other cancers considered sensitive to chemotherapy such as breast cancer. Among various research tasks in HRPC is the definition of potential surrogate end points for survival, which will facilitate the conduct of pivotal trials. Prostate-specific antigen (PSA) response rate and changes in PSA constructs (i.e., PSA doubling time and PSA velocity) are promising potential surrogate end points for future trials and are being actively evaluated at the present time. Until there is clear demonstration of a surrogate role for these alternative end points, survival remains the appropriate end point for phase III trials in HRPC. There is a need for safe and effective second- and third-line regimens for patients progressing after docetaxel, and these patients should enter clinical trials designed for this population. Mitoxantrone, vinorelbine, the platinum analogue satraplatin, and epothilone are among compounds that require careful testing in this setting. The addition of targeted therapies, such as the endothelin receptor antagonist, atrasentan, and angiogenesis inhibitors, such as thalidomide and bevacizumab, to docetaxel-based therapy is being evaluated. High-dose calcitriol may also be an effective addition to docetaxel. The extensive effort devoted to the evaluation of chemotherapy and other systemic modalities of treatment of HRPC is likely to yield additional clinical benefit for patients, making HRPC a more manageable, less lethal, and less debilitating disease.