An experimental drug being developed by Bristol-Myers Squibb Co (BMY.N) when used with chemotherapy appeared to keep advanced lung cancer from progressing modestly longer than chemotherapy alone, according to a summary of data from a mid-stage study.

The biotechnology drug ipilimumab, which augments the body’s immune response by inhibiting certain proteins, kept advanced non-small cell lung cancer from worsening about a month longer when given in addition to a chemotherapy regimen, data from an abstract of the study showed.