[GSK already has concerns with cancer drug Zejula, which is under scrutiny as a member of the PARP inhibitor class. Not the company has taken a loss in court as it will have to surrender added royalties to AstraZeneca for the drug which rolled up sales of 463 pound sterling ($571 million) last year. (GSK)]

When Emma Walmsley took over as CEO at GSK in 2017, one of her first moves was to beef up the company’s oncology portfolio with a $5.1 billion acquisition of cancer specialist Tesaro and its newly approved drug Zejula.

The ovarian cancer treatment generated 463 pound sterling ($571 million) in 2022, representing a 17% increase from the previous year. So far, so good, right?

Well, not exactly. After losing a patent case in court on Wednesday, GSK will have to surrender a portion of its sales of Zejula to Tesaro’s partner on the drug, AstraZeneca. 

The High Court of Justice Business and Property Court of England and Wales has sided with AZ in a royalty dispute, which could net the company hundreds of millions of pounds, a source told The Times when the suit was filed in 2021.

The case involves technology Tesaro licensed from AZ eleven years ago in the development of PARP inhibitor Zejula.

While Tesaro claimed that the royalty was payable only on sales for uses covered by licensed patents, AZ maintained, according to court documents, that the royalty should be calculated based on total sales of Zejula.

More than a decade later however, PARP inhibitors are under scrutiny. Last year, the FDA persuaded drugmakers to pull their PARP inhibitor approvals in late-line ovarian cancer, including GSK’s for Zejula.

Later this month, the FDA will gather an advisory committee of external experts to review AZ and Merck’s application for Lynparza in metastatic castration-resistant prostate cancer.

Reference: https://www.fiercepharma.com/pharma/gsk-will-have-pay-additional-royalties-astrazeneca-over-cancer-drug-zejula