Following the news (Monday 3 December) that GSK has struck a deal to purchase Tesaro for $5.1bn, Paul Jeng, Pharma Analyst at GlobalData, a leading data and analytics company, offers his view on the company’s prospects in oncology:

‘‘Although the acquisition of Tesaro bolsters GSK’s oncology program with Zejula, an approved PARP inhibitor for treatment of ovarian cancer, GSK is taking a risk by entering a highly competitive market currently dominated by Merck and AstraZeneca’s Lynparza.

“Given the absence of efficacy data to significantly distinguish Zejula from other PARP inhibitors, it is unclear whether GSK’s bet on Zejula will pay significant dividends unless clinical evidence justifies label expansion as first-line treatment for ovarian cancer.”

According to GlobalData’s report: ‘PARP Inhibitors in Oncology,’ the total diagnosed incident cases of ovarian cancer in the eight major markets (8MM*) are expected to increase over the next 10 years, reaching 111,817 by 2027.

“Like other drugs in its class, Zejula provides the greatest benefit for ovarian cancer patients with BRCA1/2 mutations who are sensitive to platinum-based chemotherapy. In 2017 Zejula was the first PARP inhibitor approved as second-line maintenance treatment of ovarian cancer regardless of BRCA mutations, leading to speculation that the drug had unique potential to reach a broader range of patients.

“However, since then Lynparza and Clovis’s Rubraca have also been approved for the same indication. There remains an opportunity for GSK to position Zejula as combination therapy with checkpoint inhibitors, including dostarlimab, Tesaro’s own anti-PD-1 monoclonal antibody.
“The rest of Tesaro’s oncology pipeline does not considerably mitigate the risk of GSK’s move. Early stage clinical programs include monoclonal antibodies targeting LAG-3, TIM-3, as well as PD-1, which is arguably the most crowded immune-modulating target space in oncology, and currently dominated by Merck’s Keytruda.

“Competition will only grow stronger in the coming year, as results from the Phase III PAOLA-1 trial of Lynparza as first-line maintenance treatment for ovarian cancer are expected in 2019. Clovis is seeking approval for Rubraca in metastatic castration-resistant prostate cancer (mCRPC), and Pfizer recently entered the field with its own PARP inhibitor Talzenna for treatment of patients with germline BRCA-mutated, HER2-negative breast cancer.

“Although Zejula may eventually carve a lucrative niche through label expansion, it is possible that GSK may end up allocating significant resources on clinical development just to keep pace with a crowded field.”

*8MM: eight major markets – US, France, Germany, Italy, Spain, UK, Japan, and China.