Aug 7 (Reuters) – A small study of Amgen Inc’s Lumakras drug combined with immunotherapy found it helped 29% of advanced lung cancer patients, but liver toxicity was high and further study is needed, the company said ahead of the data presentation on Sunday at the World Conference on Lung Cancer in Vienna.Nearly all of the 58 trial patients treated with the highest dose of genetic-mutation targeting Lumakras experienced elevated liver enzyme levels, and about 20% given the lowest dose saw significant liver toxicity, researchers said.The findings are the first indication of how well Lumakras works in combination with drugs that help the immune system attack cancer – Merck & Co’s (MRK.N) Keytruda and Roche Holding AG’s (ROG.S) Tecentriq.Lumakras is an oral drug designed to target a mutated form of a gene known as KRAS that occurs in about 13% of non-small cell lung cancers, the most common form of the disease, and less frequently in some other solid tumors.It was approved by the U.S. Food and Drug Administration last year for advanced lung cancer patients with KRAS mutations whose disease has worsened after treatment with chemotherapy or other medicines, but Amgen is testing whether the drug could be used as an earlier treatment.The study found that 17 out of 58 patients with advanced NSCLC – most of whom were previously treated with immunotherapies – had tumor shrinkage. Among the 17 responders, the median duration of response was 17.9 months.”It is not a slam-dunk success with the combination as we had hoped for … clearly high doses were not tolerable,” Dr. Bob Li, an oncologist at Memorial Sloan Kettering Cancer Center and the study’s lead investigator, told Reuters. “There still seems to be a path forward.”Amgen said the next iteration of the study will enroll only patients not previously treated with an immunotherapy. To limit the risk of liver toxicity, it will use a low dose of Lumakras as a lead-in, followed by the combination of Lumakras and Keytruda. Tecentriq will no longer be part of the trial.”I suspect we will have data some time next year,” said David Reese, Amgen’s research and development chief.Amgen said it is also starting a study of Lumakras in combination with chemotherapy as an initial treatment for advanced NSCLC patients who test negative for PD-L1, a protein targeted by drugs like Keytruda that helps cancer cells hide from the body’s immune system.