GlaxoSmithKline to Acquire Tesaro, Gaining PARP Inhibitor Zejula

GlaxoSmithKline and Tesaro have entered into a definitive agreement pursuant to which GSK will acquire Tesaro, an oncology-focused company based in Waltham, Massachusetts, for an aggregate cash consideration of approximately $5.1 billion. The proposed transaction will significantly strengthen GSK’s pharmaceutical business, accelerating the build of GSK’s pipeline and commercial capability in oncology.

Tesaro is a commercial-stage biopharmaceutical company, with a major marketed product, Zejula (niraparib), an oral poly ADP ribose polymerase (PARP) inhibitor currently approved for use in ovarian cancer. PARP inhibitors are transforming the treatment of ovarian cancer, notably demonstrating marked clinical benefit in patients with and without germline mutations in a BRCA gene (gBRCA).

Zejula is currently approved in the U.S. and Europe as a treatment for adult patients with recurrent ovarian cancer who are in response to platinum-based chemotherapy, regardless of BRCA mutation or biomarker status.

Clinical trials to assess the use of Zejula in “all-comers” patient populations, as a monotherapy and in combinations, for the significantly larger opportunity of first line maintenance treatment of ovarian cancer are also underway. These ongoing trials are evaluating the potential benefit of Zejula in patients who carry gBRCA mutations as well as the larger population of patients without gBRCA mutations whose tumours are HRD-positive and HRD-negative. Results from the first of these studies, PRIMA, are expected to be available in the second half of 2019.

GSK also believes PARP inhibitors offer significant opportunities for use in the treatment of multiple cancer types. In addition to ovarian cancer, Zejula is currently being investigated for use as a possible treatment in lung, breast and prostate cancer, both as a monotherapy and in combination with other medicines, including with TESARO’s own anti-PD-1 antibody (dostarlimab, formerly known as TSR-042).

In addition to Zejula, Tesaro has several oncology assets in its pipeline including antibodies directed against PD-1, TIM-3 and LAG-3 targets.

Hal Barron, chief scientific officer and president, R&D, GSK, commented, “Our strong belief is that PARP inhibitors are important medicines that have been under appreciated in terms of the impact they can have on cancer patients. We are optimistic that Zejula will demonstrate benefit in patients with ovarian cancer beyond those who are BRCA-positive as front-line treatment. We are also very excited that through this transaction, we will have the opportunity to work with an outstanding Boston-based oncology group with deep clinical development expertise and together we will explore Zejula’s efficacy beyond ovarian cancer into multiple tumour types to help many more patients.”

Lonnie Moulder, CEO, Tesaro , said, “This transaction marks the beginning of a new global partnership that will accelerate our oncology business and allow our mission of delivering transformative products to individuals living with cancer to endure. Our Board and Management team are very pleased to announce this transaction, and we are grateful to the management team at GSK for their tremendous vision and the opportunity to preserve and build upon the impact we have had in the cancer community to date.”

(Source: GlaxoSmithKline plc)