AstraZeneca PLC Steals Tesaro's PARP Thunder With Phase III Ovarian Cancer Data

March 15, 2017
By Alex Keown, BioSpace.com Breaking News Staff

LONDON – Shares of Tesaro Inc. continue to decline this morning following AstraZeneca ’s Tuesday announcement that its PARP inhibitor Lynparza delayed the recurrence of ovarian cancer by more than two years compared to placebo.

AstraZeneca’s oral tablet Lynparza is expected to line up against rival Tesaro’s niraparib, also a PARP inhibitor as a maintenance therapy for ovarian cancer patients. Following AstraZeneca’s announcement, shares of Tesaro fell 14 percent on Tuesday. This morning the stock is down another 2 percent, trading at $150.42. The stock hit a morning low of $145.

In the latest Phase III study, Lynparza was used as a maintenance therapy in a trial of 295 patients with the BRCA mutation. The study demonstrated a “significant improvement in progression-free survival (PFS) in germline BRCA-mutated (gBRCA), platinum-sensitive, relapsed ovarian cancer,” the company said in a statement. In a central-blinded review of the drug versus placebo, patients taking Lynparza saw a progression-free survival rate of 30.2 months compares to 5.5 months for the placebo, the company said. Not only that, but AstraZeneca said the drug also achieved a statistically significant result in time to second progression or death.

Sean Bohen, AstraZeneca’s chief medical officer, said in a statement that the company intends to work with regulators to bring the pills to market as soon as possible.

In 2014, Lynparza was approved by the U.S. Food and Drug Administration for the treatment of one form of ovarian cancer. In 2016, the drug generated $218 million for AstraZeneca. PARP stands for poly ADP ribose polymerase, which is an enzyme many cancer cells are more dependent upon than regular, healthy cells are.

Not only has Lynparza wowed with ovarian cancer, in February the company announced Lynparza in tablet form met primary endpoints in a Phase III trial to treat patients with HER2-negative metastatic breast cancer harboring germline BRCA1 or BRCA2 mutations. If approved for this type of breast cancer, Lynparza will be the first PARP inhibitor for that type of cancer.

The latest news regarding Lynparza is a shot in the arm for the company, particularly as the company announced in February that profit and revenue streams will likely fall in 2017 as generic drugs eat into the marketshare of its blockbuster anti-cholesterol drug Crestor.

Last year, Waltham, Mass.-based Tesaro’s Niraparib, an oral, once-daily PARP inhibitor, met its endpoints of progression-free survival (PFS) in a Phase III trial. At the time Tesaro announced its Phase III results, some analysts were saying that niraparib was the PARP inhibitor to beat in ovarian cancer. However, with AstraZeneca’s latest announcement, Lynparza may be the holder of that title now.

However, another PARP manufacturer is riding high as a result of the latest news. Shares of Clovis Oncology have jumped due to its PARP drug Rubraca, which was approved by the FDA in December. The drug was approved for patients who have already gone through two chemotherapy treatments, but Clovis is looking to expand the use of the drug as a maintenance therapy.

Pfizer is also looking to join in as well. When that company acquired Medivation last year, it also picked up an experimental PARP treatment.