"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  percent compared to chemotherapy alone in preselected patients whose tumors had been tested using a biomarker.  And when given with two older chemotherapy drugs in nonselected patients it was almost twice as likely to shrink tumors as chemotherapy alone.  Another similar drug from Roche also demonstrated broad efficacy as a socalled secondline option in patients who had received prior treatment.  Remember this day. Its a new day for lung cancer treatment Stefan Zimmermann of Lausannes University Hospital told reporters at the European Society for Medical Oncology ESMO congress as the results were presented.  An editorial in the New England Journal of Medicine where the Merck monotherapy results were published said Keytruda could become a new standard of care.  The various findings suggest that treating lung cancer  the biggest cancer killer globally  with powerful new immune systemboosting medicines is going to involve more permutations than some experts originally expected.  Rival drugmaker BristolMyers Squibb had tried a catchall approach with its Opdivo drug but it failed to help previously untreated patients when given on its own in a trial that included people with low levels of a protein called PDL.  Keytruda as a sole agent was targeted only at patients with high PDL making them more receptive to immunotherapy.  Lead researcher Martin Reck of Germanys Lung Clinic Grosshansdorf predicted that testing for the PDL biomarker would now become standard from today.  U.S. regulators are expected to decide whether to approve Keytruda for firstline nonsmall cell lung cancer the most common type by Dec. .  Merck had already said in June that Keytruda worked in the trial but the scale of the benefit was only disclosed at ESMO.  COMBINATION THERAPY  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 randomized Phase II study.  Many experts have been skeptical about this approach and investors expectations up until now have been quite low.  In the event researchers reported that Mercks combination cut the risk of disease progression or death by  percent compared to chemotherapy alone after . months while  percent of patients saw their tumors shrink versus  percent.  Patients in this trial were not selected by PDL expression but the study did find that those with higher PDL had a higher response.  Roger Perlmutter Mercks head of research said both trials suggested Keytruda could offer a broad array of patients meaningful improvement over standard platinumbased 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 bodys natural killer cells to home in on tumors.  They are expected to sell tens of billions of dollars in the years ahead with lung cancer the largest market.  Up until now Bristol has dominated the field but investors have started to shift their bets with forecasts for Opdivo declining while those for Keytruda have risen.  The current consensus forecast among analysts is for Keytruda sales to reach  billion in  with Opdivo selling . billion according to Thomson Reuters data.  Results of Bristols failed Opdivo trial which included patients with tumors testing only  percent or higher for PDL against the  percent cutoff used by Merck were also presented at ESMO.  These showed progressionfree survival was . months with Opdivo and . months with chemotherapy although the difference was not statistically significant. Overall survival was . months with Opdivo versus . 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 companys 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."