In an effort to get more gonadotropin-releasing hormone (GnRH) analogues to market for advanced prostate cancer patients, the FDA has published final guidance that advises sponsors to conduct single-arm trials using T levels as pharmacodynamics/response biomarkers.

The agency expects these trials to show that participants attained a castrate plasma testosterone (T) level, maintained castrate T levels until the end of a dosing interval and maintained castrate T levels starting immediately after subsequent doses of the trial drug.

Because plasma T levels have served as pharmacodynamic/response biomarkers for traditional approvals of GnRH analogues for advanced prostate cancer, it’s essential that these trials use robust, fully validated bioanalytical methods for measuring them, the guidance notes.

To show the drug has these effects, the agency recommends the treatment period be at least double the length of the dosing interval. For investigational products that act over a short amount of time, such as a single month, the treatment period should extend over three to four dosing intervals, the guidance says. Sponsors should consult with the FDA on randomized designs meant to support comparisons of safety and efficacy among GnRH analogues.

Read the full guidance here: https://bit.ly/3LRnJ0r.