Avastin does NOT extend survival of patients with HRPC

The pharmaceutical company Roche announced this morning that the combination of bevacizumab (Avastin) with docetaxel and prednisone does not extend the overall survival of men with hormone-refractory prostate cancer (HRPC) compared to docetaxel + prednisone alone.

While this will obviously be a disappointment to men with advanced, progressive disease who have been hoping for additional options for treatment once hormone therapy alone can no longer suspend disease progression, The “New” Prostate Cancer InfoLink has long wondered whether a successful outcome in this trial would be a good thing.

This clinical trial (CALGB 90401) was designed as a multicenter, randomized, double-blind, placebo-controlled Phase III study to evaluate whether the addition of bevacizumab to standard chemotherapy with docetaxel and prednisone could extend the lives of men with HRPC (also known as castration-resistant prostate cancer of CRPC). Just over 1,000 patients were enrolled into the trial, and the  primary endpoint of the study was overall survival. Other secondary endpoints of the study included progression-free survival, PSA response rate, and safety.

The media release from Roche this morning gives no specific data regarding the results of this trial. It does state, however, that more detailed data will be presented later this year at the annual meeting of the American Society of Clinical Oncology (on June 4 to 8, in Chicago). It also says that, “A preliminary assessment of safety performed by CALGB has shown adverse events that have been previously observed in pivotal trials with Avastin.”

Our concern about this trial had always been whether it might show a very small survival benefit (another few weeks) for the combination of bevacizumab with docetaxel and prednisone compared to chemotherapy alone. In such a case, doctors and their patients would have been faced with the difficult task of deciding whether the additional survival was sufficient to counterbalance the well-known risks associated with bevacizumab.

Bevacizumab is an extraordinary and valuable biologic agent. It has shown very clear and significant benefits in the treatment of advanced forms of colorectal and lung cancers, and has revolutionized research into the field of angiogenesis. However, studies of the efficacy of bevacizumab in some other forms of cancer have provided data that are less clear cut relative to the risks. Bevacizumab has been associated with a series of very serious side effects in a small proprotion of patients, including gastrointestinal perforations and severe or even fatal hemorrhages. If the combination of bevacizumab with docetaxel and prednisone had increased overall survival from the proven 18.9 months without bevacizumab to (say) 19.4 months with its addition, it might have been very difficult for patients and their oncologists to balance the potential risk against the potential benefit on an individual basis.

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