Abiraterone acetate in chemotherapy-naive mCRPC: full data published

An article published this week in the New England Journal of Medicine gives the full results of the Phase III trial of abiraterone acetate + prednisone in men with chemotherapy-naive, metastatic, castration-resistant prostate cancer (mCRPC). These data were originally reported at the ASCO annual meeting in 2011.

Unfortunately, only the abstract of the full paper by Ryan et al. is available to non-subscribers, but (based on that abstract) it does not appear as though the full paper provides any new information that has not already been widely reported on this site and elsewhere. Abiraterone acetate has already been approved by the US Food & Drug Administration to treat men with chemotherapy-naive mCRPC.

6 Responses

  1. “Over a median follow-up period of 22.2 months, overall survival was improved with abiraterone–prednisone (median not reached, vs. 27.2 months for prednisone alone; hazard ratio, 0.75; 95% CI, 0.61 to 0.93; P = 0.01).”

    If median follow up is 22.2 then how is prednisone alone 5 months longer at 27.2?

  2. Dear Tarhoosier:

    Because the median follow-up period for all patients is not the same at all as the median overall or the median radiographic progression-free survival AND because the way these data are analyzed allows for the fact that a trial can demonstrate effectiveness long before all patients demonstrate median survival data.

    I am not a statistician, but I do know that these numbers are potentially (and in fact) correct. If they weren’t, the FDA would never have approved the product and the NEJM would never have published the paper.

  3. Regarding overall survival rate, the first poster seems to have misread something. Here’s how I read the report.

    — At a virtual-two-year mark (median 22.2 months), it could be determined that the control group (placebo + prednisone) had a median survival time of 27.2 months.

    — At the same virtual-two-year mark, median survival time for the treatment group (abiraterone + prednisone) was large enough that it could not yet be determined — in other words, half had not yet died, and the survival rate was good enough that it was not yet possible to project how soon it would be before half would die.

    This report was of more-than-usual interest for me, because today was the day I started abiraterone + prednisone for my chemo-naive cancer. Regardless of what the median survival rate turns out to be (when it can be determined, which I hope won’t occur for quite some time), I’m hoping to be way out on the long tail of the distribution. :-)

  4. Dear Paul:

    Just so that we are clear, we are never going to know what the overall survival time might have been for men taking abiraterone + prednisone in this trial.

    Why? Because the indpenedent trial monitoring committee recommended stopping the trial on the basis of the (statistically significant) difference in radiological progression-free survival, and patients who had been taking the placebo + prednisone were all offered abiraterone + prednisone instead at that time.

  5. Now we need FDA approval for hormone-refractory patients who do not yet show evidence of metastases, rather than waiting for such metastases to have developed.

  6. Well … that will only happen if the manufacturer chooses to conduct the relevant clinical trials.

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