Study: Janssen’s Delay of Generics for Zytiga Achieved $2.05 Billion in Additional Sales

After generic entry, Zytiga’s market share fell to about 14% and monthly net sales across the entire market fell 85%.

Efforts by pharmaceutical companies to delay a generic entry with patent extensions can generate significant sales for companies and can be costly to the health care system, investigators in a newly released study found. Investigators profiled the example of Zytiga (abiraterone) developed by Janssen. They estimated that from December 2016, when the original patent was to expire, to December 2020, when generics became available after the courts ruled against the patent extension, Zytiga sales gained an additional $2.05 billion.

“The experience of abiraterone highlights a key challenge facing the modern drug market—delaying generic entry can be highly profitable to branded manufacturers,” investigators wrote. “Importantly, even an ultimately successful patent challenge requires substantial time and has major implications for consumer spending on pharmaceuticals.”

In 2011, the FDA approved abiraterone for the treatment of metastatic castrate-resistant prostate cancer. The use of abiraterone was then further expanded in 2017 to treat patients with metastatic castrate-sensitive prostate cancer. The original patent was filed in 1994 and set to expire in December 2016.

Janssen filed a patent in 2014 for co-administration of Zytiga with prednisone. This patent was controversial from the start. Investigators said the standard of care was to use prednisone with Zytiga because the therapy triggers glucocorticoid deficiency.

Using data from IQVIA’s National Sales Perspective and SSR Health US Brand Rx Net Pricing Tool were able to assess the additional sales Zytiga achieved during its extended patent monology.

Not unsurprisingly, the entry of generics reduced Zytiga’s market share to about 14% and monthly net sales across the entire market fell roughly 85% to $23 million in December 2020, research said.