Merck looks for a return on its Lynparza investment

When Merck & Co bought into Astrazeneca’s Parp inhibitor Lynparza in 2017 it also kicked off a series of combo pivotal studies designed to broaden the reach of Keytruda. This clinical work alone is thought to be costing Merck $1.2bn, Evaluate Pharma data calculate.

The figures are important because several of these trials, including in ovarian, lung and breast cancers, might be reading out this year. Unfortunately for Merck this effort has got off to an inauspicious start, with the first pivotal combo study, Keylynk-010, in prostate cancer, being halted after an interim analysis found it to be futile.

Keylynk-010 had tested Keytruda plus Lynparza in castrate-resistant prostate cancer patients who had already failed chemotherapy and either Zytiga or Xtandi, pitting the combo against Xtandi or Zytiga in the two respective populations. A data-monitoring board this week recommended scrapping it after seeing no benefit in either of its co-primary endpoints, radiographic progression-free and overall survival.

More on the way

The study was the first of several in the Keylynk programme to yield a result.

Next up are three trials that will add Lynparza as maintenance therapy while patients are still in response to front-line Keytruda plus chemo, in cancers where Keytruda plus chemo is already approved: ovarian cancer (Keylynk-001), squamous NSCLC (Keylynk-008) and triple-negative breast cancer (Keylynk-009). Interestingly, the last study recruits all-comers even though Keytruda’s front-line label mandates ≥10% PD-L1 expression.

Under the companies’ 2017 agreement Merck paid Astra $1.6bn up front, plus $750m for “certain licence options”, for a 50% share of gross profits generated by Lynparza. Monotherapy Lynparza trial costs were to be shared, while Astra took on the burden of funding any studies combining Lynparza with  Imfinzi.

Those in which the Parp inhibitor was being combined with Keytruda, however, were to be the sole responsibility of Merck. According to Evaluate Omnium's estimates, the eight Keylynk trials combined amount to a cost of $1.2bn, including $123m for the failed ‘010 study.

As a brand Lynparza has sold a cumulative $6bn since the 2017 deal, and is expected to bring in $5.6bn in 2026 alone. Even a conservative 85% gross profit margin suggests that Merck might already be close to recouping its up-front fee. As for the Keytruda combo studies, however, the jury is still out.