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# Churchill Pharma NDA for Yonsa Accepted by FDA
- URL: https://www.fdaweb.com/churchill-pharma-nda-for-yonsa-accepted-by-fda/
- Published: 2017-07-20T12:00:00.000Z
- Updated: 2026-09-14T22:35:27.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5139176

FDA has accepted for review a Churchill Pharmaceuticals NDA for Yonsa (abiraterone acetate) ultramicrosize tablets for treating metastatic castration-resistant prostate cancer. The agency has set a 3/19/2018 user fee review action target date.

The submission was based on data from the *STAAR* study, a randomized, open label patient trial in the U.S. comparing Yonsa 500 mg once daily plus methylprednisolone 4 mg twice daily, to another formulation of abiraterone acetate (Zytiga) 1,000 mg once daily plus prednisone 5 mg twice daily. The primary endpoint was comparative lowering of serum testosterone at pharmacodynamic steady-state.

  
Yonsa is a CYP17 inhibitor that sees its active ingredient converted *in vivo* to abiraterone, an androgen biosynthesis inhibitor, that inhibits 17 a-hydroxylase/C17,20-lyase, according to the company. This enzyme is expressed in testicular, adrenal and prostatic tumor tissues and is required for androgen biosynthesis, it says.