* Keytruda cuts risk of death 40 pct in big lung cancer study
* Drug also improves outcomes when given with chemotherapy
By Ben Hirschler
COPENHAGEN, Oct 9 (Reuters) - Merck & Co scored a double hit on Sunday with new clinical data showing its Keytruda immunotherapy offered big benefits in previously untreated lung cancer patients, either when given on its own or with chemotherapy.
As a monotherapy, Keytruda halved the risk of disease progression and cut overall deaths by 40 percent compared to chemotherapy alone in pre-selected patients whose tumours had been tested using a biomarker.
In contrast to rival Bristol-Myers Squibb, whose Opdivo drug failed to help such first-line patients, Keytruda was targeted at people who express high levels of a protein called PD-L1, which makes them more receptive to immunotherapy.
U.S. regulators are expected to decide whether to approve Keytruda for first-line non-small cell lung cancer, the most common type, by Dec. 24.
Merck had already said in June that Keytruda worked in the trial but the scale of the benefit was only disclosed at the annual European Society for Medical Oncology (ESMO) congress.
The second trial, mixing Keytruda with chemotherapy, was much smaller but was notable because it was the first time that a combination of immunotherapy and chemotherapy has been shown to work in a randomised Phase II study.
Many experts have been sceptical about this approach and investors' expectations, up until now, have been quite low.
In the event, researchers reported that Merck's combination cut the risk of disease progression or death by 47 percent compared to chemotherapy alone after 10.6 months, while 55 percent of patients saw their tumours shrink versus 29 percent.
Patients in this trial were not selected by PD-L1 expression but the study did find that those with higher PD-L1 had a higher response.
Roger Perlmutter, Merck's head of research, said both trials suggested Keytruda could offer a broad array of patients meaningful improvement over standard platinum-based chemotherapy, which is now more than two decades old.
Drugs like Keytruda and Opdivo work by taking the brakes off the immune system and allowing the body's natural killer cells to home in on tumours.
They are expected to sell tens of billions of dollars in the years ahead, with lung cancer, the biggest cancer killer globally, viewed as the largest market.
Results of Bristol's failed Opdivo trial, which included patients with tumours testing only 5 percent or higher for PD-L1 against the 50 percent cut-off used by Merck, were also presented at ESMO.
These showed progression-free survival was 4.2 months with Opdivo and 5.9 months with chemotherapy, although the difference was not statistically significant. Overall survival was 14.4 months with Opdivo versus 13.2 months.
The failure of Opdivo to work for "all comers" in lung cancer was first announced in August, without any details. It was a major setback for Bristol, wiping out around a quarter of the company's market value, and it has caused investors to rethink prospects for immunotherapy treatments.
Many now believe that combination therapy is the way ahead, with Bristol and AstraZeneca working primarily on using two immunotherapies together, while Roche and Merck look at adding chemotherapy.
Results of Merck's two trials were published online in the New England Journal of Medicine and the Lancet Oncology journal. (Reporting by Ben Hirschler; Editing by Stephen Powell)