"Merck  Cos approved Keytruda lung cancer treatment provided superior overall survival to chemotherapy in a latestage study of patients with advanced disease whose tumors produce a protein called PDL associated with increased risk of the disease.  The U.S. drugmaker on Monday said patients taking the approved  milligram dosage of Keytruda and those taking an experimental  milligram dose had longer overall survival compared with those taking docetaxel a standard treatment for non small cell lung cancer NSCLC the most common form of lung cancer. Keytruda thereby met its main goal of the study.  Patients whose tumors had especially high levels of PDL also went longer without a progression of disease than those taking docetaxel Merck said. Those whose tumors expressed PDL but not at high levels did not show such a statistically significant benefit in progressionfree survival.  Safety of Keytruda was consistent with what had been seen in previous trials among lung cancer patients Merck said in a release that included only summary topline information from the results.  More detailed data from the study will be provided soon Merck said adding that it will ask the U.S. Food and Drug Administration later this year to add the new data to the drugs package insert label.  U.S. regulators in October approved Keytruda on an accelerated basis for patients with advanced nonsmall cell lung cancer whose tumors produce PDL. The approval was contingent on the company providing more detailed data in the future on Keytrudas safety and effectiveness.  Keytruda and a similar treatment from BristolMyers Squibb Co called Opdivo are antibodies designed to block the interaction between PDL and another protein PD whose natural function is to put checks on the immune system. By blocking the interaction the drugs aim to enable the patients own immune system to recognize and therefore attack the cancer.  Wall Street analysts expect cancer immunotherapies to earn combined annual sales of over  billion by ."