Churchill Pharmaceuticals Announces NDA Filing Acceptance for YONSA

Churchill Pharmaceuticals announced the New Drug Application (NDA) for YONSA (abiraterone acetate) ultramicrosize tablets has been accepted for filing by the U.S. Food and Drug Administration (FDA). Under the Prescription Drug User Fee Act (PDUFA), the FDA has set a target date of March 19, 2018 to complete its review.

The submission was based primarily on the final results of the STAAR Study, a randomized, open label patient trial in the U.S. comparing YONSA 500mg once daily plus methylprednisolone 4 mg twice daily, to another formulation of abiraterone acetate (Zytiga) 1000 mg once daily plus prednisone 5 mg twice daily. STAAR was an evaluation of 53 male patients with metastatic castration-resistant prostate cancer  (mCRPC), a mean age of 75 years and a majority of whom had Gleason scores >7. Over 90% of patients treated with YONSA achieved absolute testosterone levels of <1 ng/dL at each time point, while non-detectable testosterone levels (≤0.1 ng/dL) were achieved in a higher percentage of patients treated with YONSA versus patients treated with the comparator.

"We are pleased that the NDA for YONSA has been accepted. The notification from the FDA indicated that the application is sufficiently complete to permit a substantive review and that no potential review issues have been identified. Our team looks forward to working closely with the FDA throughout the review process," said Scott Megaffin, President, Churchill.

YONSA is an investigational oral agent, formulated as abiraterone acetate ultramicrosize tablets. YONSA is a CYP17 inhibitor being developed for the treatment of metastatic castration-resistant prostate cancer in combination with methylprednisolone. The active ingredient is converted in vivo to abiraterone, an androgen biosynthesis inhibitor, that inhibits 17 α-hydroxylase/C17,20-lyase (CYP17). This enzyme is expressed in testicular, adrenal and prostatic tumor tissues and is required for androgen biosynthesis.  YONSA ultramicrosize tablets have double the bioavailability of the comparator formulation of abiraterone acetate. YONSA has been formulated using the SoluMatrix Fine Particle Technology.

The STAAR Study (CHL-AA-201, A Randomized, Open-Label, Active-Controlled, Multi-Center Study to Evaluate Serum Testosterone Levels in Patients with Metastatic Castration-Resistant Prostate Cancer) was an 84-day study in the U.S. comparing YONSA in combination with methylprednisolone against Zytiga in combination with prednisone. The primary endpoint was comparative lowering of serum testosterone at pharmacodynamic steady-state. Additional secondary endpoints included safety assessments, PSA and pharmacokinetic measurements. The full results of the STAAR Study will be presented at a future scientific meeting.