Sun Pharma Gets FDA Go-Ahead for Yonsa for Prostate Cancer

Sun Pharmaceutical Industries, located in Mumbai, Indi and Princeton, New Jersey received approval from the U.S. Food and Drug Administration (FDA) for Yonsa (abiraterone acetate) to treat metastatic castration-resistant prostate cancer (mCRPC). Sun will launch the drug in the U.S. via a licensing deal with Churchill Pharmaceuticals, the original developer of the drug. Churchill is eligible for upfront fees, as well as milestone payments and royalties.

In January, a U.S. court invalidated a patent that Johnson & Johnson had on its prostate cancer drug Zytiga. The Patent Trial and Appeal Board indicated that a J&J patent describing how to administer Zytiga was obvious, and shouldn’t have been granted. This was a victory for Argentum Pharmaceuticals, and opened up the possibility of generic competition.

Sun’s Yonsa isn’t a generic, but it is definitely a competitor for J&J’s blockbuster Zytiga. They both contain the same active ingredient, abiraterone acetate, but the Sun formulation doesn’t run into trouble with J&J’s patents.

Yonsa is formulated for administration in combination with methylprednisolone. Zytiga is approved for use in combination with prednisone, a different steroid. In 2017, Zytiga brought in $1.23 billion in the U.S.

After the patent ruling, Vamil Divan, an analyst with Credit Suisse, wrote that he didn’t “expect the final patent remaining on Zytiga to hold up to challenge, and we have been anticipating a generic entry following the expiration of a 30-month stay in October 2018.”

J&J is expected to appeal that patent decision, but barring any suits involving Sun or Churchill, Sun’s Yonsa should enter the market.

“We are pleased to add Yonsa to our growing oncology portfolio and continue to deliver on Sun Pharma’s commitment for enhanced patient access to innovative cancer therapies,” said Abhay Gandhi, chief executive officer, North America, for Sun Pharma, in a statement.

Yonsa is a CYP17 inhibitor. It utilizes a proprietary SoluMatrix Fine Particle Technology to create a smaller particle size formulation of abiraterone acetate tablets. The active ingredient is converted in the body to abiraterone, which inhibits CYP17, which is expressed in testicular, adrenal and prostatic cancer tissues.

In a U.S.-based randomized, open-label clinical trial, 500mg of Yonsa once per day and methylprednisolone 4 mg twice a day, was observed to treat 90 percent of prostate cancer patients with absolute testosterone levels of <1 ng/dL. This was an improvement on Zytiga. The trial also showed no statistical difference between Zytiga and Yonsa, but Yonsa required lower dosages than Zytiga.

Churchill Pharmaceuticals, based in King of Prussia, Pennsylvania, announced the New Drug Application for Yonsa on July 20, 2017. The submission was based on the results of the STAAR Study.

“Yonsa represents a new potential treatment option for the nearly 30,000 men diagnosed annually in the U.S. with mCRPC,” said Ben Steinmetz, Churchill’s senior vice president, Commercial, in a statement at the time. “Yonsa sets the stage in our initial commercial approach with an exciting and innovative opportunity to deliver on the Churchill commitment to responsibly enhance product access to critical therapies.”