More on docetaxel given every 2 weeks

A few days ago we reported on a paper by a Finnish research team who had compared treatment of men with mCRPC with docetaxel given every 2 weeks as opposed to the standard therapy of every 3 weeks.

We have now had the opportunity to read the full text of this paper, so we are able to add some clarification to our earlier comments.

In the first place, the 15 of the 361 patients initially entered into the study (seven to be treated with docetaxel every 2 weeks and eight with docetaxel every 3 weeks) who were subsequently excluded from the analysis were identified as either not having fully met the study eligibility criteria or (in three cases) had withdrawn their consent for participation in the study. So these exclusions seem completely reasonable.

Secondly, and perhaps much more importantly, despite the fact that the authors make relatively little mention of this fact, there was a very real (and statistically significant) difference in the overall survival of the patients in the two arms of the trial:

  • Median overall survival for men on Regimen A (the standard regimen of docetaxel + prednisolone every 3 weeks) was 17.0 months (range, 15.0 to 19.0 months).
  • Median overall survival for men on Regimen B (the alternate regimen of docetaxel + prednisolone every 2 weeks) was 19.5 months (range, 15.9 to 23.1 months).
  • The hazard ratio (HR) was 1.4, and p-value was 0.021.

In addition, there was a better median time to disease progression or death (TTP) for the patients in Regimen B (although this was only barely statistically significant):

  • Median TTP for men on Regimen A was 14.6 months (range, 13.2 to 16.0 months).
  • Median TTP for men on Regimen B was 15.8 months (range, 13.6 to 18.1 months).
  • HR = 1.3 and p-value = 0.047.

As we noted previously, it would help if there was data from a larger study available to confirm the data from this relatively small Phase III trial. However, the significant reduction in side effects associated with the smaller, more frequent dose of docetaxel used in Regimen B, combined with an apparent increase in median survival, is strongly suggestive of a potential clinical benefit from using docetaxel every 2 weeks as opposed to every 3 weeks in routine clinical practice.

The relatively conservative conclusion offered by Kellokumpu-Lehtinen et al. in their paper states only that:

Administration of docetaxel every 2 weeks seems to be well tolerated in patients with castration-resistant advanced prostate cancer and could be a useful option when 3-weekly single-dose administration is unlikely to be tolerated.

Editorial note: The “New” Prostate Cancer InfoLink thanks Prof. Pirkko-Liisa Kellokumpu-Lehtinen of the University of Tampere for kindly providing us with a copy of the full text of this paper.

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