If the initial results are confirmed in a Phase III study already underway, it would be the first treatment developed in the past decade that can improve outcomes for patients with late-stage lung cancer.
Patients who received Synta's drug ganetespib had a median overall survival of 9.8 months, compared with 7.4 months for those who received the standard treatment.
The drug works by blocking a type of protein known as molecular chaperones that help newly formed proteins assume the proper shape needed to perform their specific biological function.
Since many of the proteins driving lung cancer growth require this chaperone -- heat shock protein 90, or Hsp90 -- blocking it can disable multiple cancer-fueling proteins at the same time.
Researchers believe this may still work in patients who develop mutations that make them resistant to traditional targeted drugs because it ought to also inhibit the function of mutated proteins.
"This is the first randomized study to demonstrate therapeutic benefit with a heat shock protein inhibitor in patients with cancer," said lead study author Suresh Ramalingam, a professor of medical oncology at Emory University in Atlanta, Georgia.
"We hope that the ongoing Phase III study will confirm our findings, as patients with this common form and stage of lung cancer urgently need more effective treatments."
Early Hsp90 drugs did not succeed in previous clinical trials because they were not significantly effective at extending life and caused liver toxicity.
This is the first randomized clinical trial of a second generation inhibitor and the first time this class of drugs was shown to be both safe and effective.
The phase III study examined 252 patients with Stage IV lung adenocarcinoma, which accounts for about 45 percent of the 170,000 non-small cell lung cancer cases diagnosed each year in the United States.
It was presented at the annual meeting of the American Society of Clinical Oncology in Chicago.