GSK and AstraZeneca's PARP Inhibitors Will Flex Their Muscles at ESMO

Giving a presentation

PARP inhibitors will be taking center stage at the European Society of Medical Oncology Congress as rival drugmakers aim to show off data that supports broader use of the drug in treating various cancers.

Both AstraZeneca and GlaxoSmithKline will showcase the power of Lynparza (co-developed with Merck) and Zejula, respectively. At ESMO, both companies will highlight clinical data supporting the efficacy and safety of the PARP inhibitors. AstraZeneca will provide details of Lynparza studies in ovarian cancer and prostate cancer, as well as pancreatic cancer. GSK will present Zejula data from its late-stage ovarian cancer trial, as well as data from breast cancer studies.

PARP inhibitors have mainly been tied to cancers that have a BRCA mutation. However, a recent study conducted by UT Southwestern has shown that PARP inhibitors could have broader effectiveness in treating other types of cancer, including ovarian and prostate cancer. PARP stands for poly ADP ribose polymerase, which is an enzyme many cancer cells are more dependent upon than regular, healthy cells are. PARP inhibitors are designed to disable DNA repair pathways in cancer cells, which make it difficult for those cells to survive.

Positive data that is well-received is something both companies need to bolster their oncology programs, an analyst told Reuters. Echoing the UT Southwestern study, John Bowler, an asset manager at Schroders, told Reuters that the “utility of PARP inhibitors” could become much broader than patients with the BRCA mutation.

“That becomes relevant when you start thinking about the drugs’ role in other tumor types like prostate cancer and breast cancer where the incidence of new patients each year is much greater than in ovarian cancer,” Bowler told Reuters.

For GSK, the data could be especially important since the company laid out its new R*D strategy last year that focuses on genetics and the immune system. R&D Head Hal Barron laid out a strategy that focuses on the development of medicines that target mechanisms of action with strong human genetic validations. Those targets have a higher probability of success, which means a shift to a genetics-driven portfolio. Bowler said the data from the Zejula trials will be an important milestone for Barron’s strategy. GSK acquired Tesaro Oncology, the maker of Zejula, in December 2018 for $5.1 billion. That bet appears to have paid off. In July, GSK reported that Zejula hit the mark in a Phase III ovarian cancer study. The PRIMA study met its primary endpoint of a statistically significant improvement in progression-free survival for women regardless of their biomarker status. The PRIMA study is one of the Zejula trials that GSK will tout at ESMO.

Not to be outdone, last month AstraZeneca reported that for the second time, Lynparza met its endpoints as a potential first-line treatment for ovarian cancer in a Phase III trial. The Phase III PAOLA-1 trial assessed Lynparza as a companion to the standard of care treatment Bevacizumab (Genentech’s Avastin) in women with advanced ovarian cancer. The combination treatment proved to be a powerhouse in the intent-to-treat population with a statistically-significant and clinically-meaningful improvement in progression-free survival.

In its analysis of the PARP field, Reuters predicted that Lynparza will generate about $3.1 billion by 2023, while Zejula will post about $1.1 billion in sales that year.

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