The key prostate cancer presentations today at the annual meeting of the American Society of Clinical Oncology (ASCO) were all given at a morning session on high-risk and advanced prostate cancer.
We have previously commented on the presentation by Ryan giving the detailed information from the Phase III clinical trial of abiraterone acetate + prednisone in the treatment of men with chemotherapy-naive, metastatic, castration-resistant prostate cancer (mCRPC) and the presentation by Taplin on the use of abiraterone acetate + LHRH therapy in the pre-surgical treatment of men with high-risk prostate cancer. The actual oral presentations of these two papers offered us no unexpected additional insights.
A discussion by Halabi immediately following Ryan’s presentationprovided a detailed statistical assessment of the rationale for breaking the blinding on the abiraterone + prednisone trial in chemotherapy-naive mCRPC. It would be impossible for us to do justice to Dr. Halabi’s careful assessment of the accuracy of this decision. Suffice it to say that she made two very clear points:
- She believed it was the correct decision under the circumstances, but
- She also made it clear that this had to have been a very close call.
This analysis raised a question from the audience about whether the FDA would concur that the available data supported approval of abiraterone acetate + prednisone for the treatment of chemotherapy-naive mCRPC. It has to be said that the FDA and other regulatory agencies are likely to look at these data with great care.
The “New” Prostate Cancer InfoLink is optimistic that the FDA will approve the use of abiraterone acetate + prednisone in the treatment of chemotherapy-naive mCRPC based on these data. However, it is evident that if there are data in the actual clinical trial reports that are not fully supportive of an approval, the FDA may have serious reservations about the strength of the available data to support an approval.
The other major presentation for the session was an update by de Bono on outcomes and quality of life-related data based on the AFFIRM trial of enzalutamide (MDV3100) compared to a placebo in treatment of men with mCRPC who had already progressed after treatment with docetaxel-based chemotherapy. This presentation was followed by a discussion of the paper by Kelly, but neither the paper nor the discussion offered any surprising new insights.
It should be noted that Dr. de Bono did make the point that there were potentially good explanations for at least four of the five cases of seizures among patients in the enzalutamide arm of the trial. However, he was equally emphatic that there were no reports at all of seizures in the placebo arm.