(CNN) - Combining an immunotherapy drug with chemotherapy nearly doubled the survival time of some lung cancer patients compared to patients treated with chemotherapy alone, new research published Monday in the New England Journal of Medicine showed.
The study results apply only to patients whose lung cancer does not begin in the squamous cells (or surface lung cell layer) and who also lack certain genetic mutations. Of the two types of lung cancer, small cell lung cancer is less common than non-small cell lung cancer, which affects up to 85% of all lung cancer patients. Worldwide, lung cancer causes 1.69 million deaths annually.
"Non-small cell lung cancer is actually the leading cause of cancer death in the world even though it's not the most common cancer," said Dr. Leena Gandhi, lead investigator of the study and director of the thoracic medical oncology program at Perlmutter Cancer Center at NYU Langone Health.
Gandhi explained that the reason non-small cell lung cancer is so deadly is the existing chemotherapy drugs provide only limited survival benefits for patients. "A matter of months, not years," she said.
Immunotherapy, which harnesses the body's immune system to attack tumors, is known to improve survival in patients who have already been treated with chemo.
Gandhi wondered, Would using immunotherapy earlier in treatment, alongside chemotherapy, do more for patients?
The study, a phase III clinical trial testing treatment effectiveness and side effects, included 616 patients at 118 medical facilities around the globe.
One group of 400 patients received standard chemotherapy and the immunotherapy drug pembrolizumab, while a smaller group of patients received chemotherapy.
Pembrolizumab, sold under the brand name Keytruda, is an FDA-approved drug sold by a subsidiary of Merck & Company, Inc. that sponsored this study.
The combined use of standard chemotherapy with pembrolizumab was "superior in terms of response -- keeping people alive without progression of their cancer -- and improving the overall survival of patients with metastatic lung cancer compared to chemotherapy alone," said Gandhi. "And the differences were not small."
For patients receiving the combined therapy, the chance of death or progression of their cancer was reduced by 48% compared to the patients receiving only chemotherapy. The most common side effects were nausea, anemia and fatigue and in both groups about 65% of patients experienced severe side effects. However, the risk of one side effect, acute kidney injury, was higher for combination treated patients: 5.2% vs. 0.5%.
Dr. Jorge Gomez, a volunteer spokesperson for the American Lung Association and a medical oncologist and director of thoracic oncology at Mount Sinai Hospital in New York, explained that "about 220,000 patients are diagnosed with lung cancer a year in the US."
Non-squamous lung cancer patients make up about 80% of all the non-small cell lung cancers, so that amounts to over 150,000 patients in the US each year, said Gomez, who was not involved in the new study.
"What we look at in these trials is overall survival -- how long patients live -- and we look at a number called the median survival -- how long 50% of patients live," said Gomez. Median survival is met when 50% of the patients die.
For non-squamous non-small cell lung cancer patients, median survival with chemotherapy alone is somewhere around 11 or 12 months, he said. Yet, median survival among the study participants who received both immunotherapy and chemo has not yet been reached.
"It's already been 21 months," said Gomez. "The differences are big enough now that you know it's going to be a very big number and it's important to get this information to people so they can start using this regimen."
Gomez believes it could be as high as double chemotherapy alone, "which would be very impressive," he said. "I only treat lung cancer and I've been doing that for about 20 years. These drugs are very, very interesting. Now, not everybody benefits unfortunately, but some of the people who benefit seem to benefit in a way we've never seen."
Recalling a patient with advanced lung cancer whose tumor disappeared and has not grown back after finishing treatment 24 months ago, Gomez said, "I'm now becoming much more optimistic that if we can really find a way to perfect this treatment and to really figure out who are the patients who do the best and why that we may be able to do something like get rid of lung cancer for at least some patients."