A new cancer drug called Opdivo is working so well that it ended a lung cancer trial two years early. 

The drug Opdivo was approved by the Food and Drug Administration in late December for treatment on advanced melanoma - cancer in the skin cells.

Pharmaceutical giant Bristol-Myers Squibb, which is marketing Opdivo, was conducting a study with 234 patients comparing Opdivo to Docetaxel, a type of chemo used for patients whose cancers have recurred after treatment, reported ABC affiliate News 10

The study was called off Monday by Bristol-Myers because Opdivo was working so well. The trial was scheduled to continue for another two years. 

Opdivo works by "removing a brake that cancer puts on the immune system," reported News 10. In some cases, removing this brake is enough to allow the patient's immune system to fight and contain the cancer.

The called-off study was specifically looking at a type of lung cancer called squamous cell non-small cell lung cancer, which accounts for about 20 to 30 percent of all lung cancers, reported News 10.

"We as a lung cancer community are incredibly excited about the activity of immunotherapy in various aspects of the disease," Pasi Janne, director of the Lowe Center for Thoracic Oncology at the Dana-Farber Cancer Institute in Boston, told News 10. "It's a disease where we're desperately looking for new therapies." 

Janne, who is also a professor at Harvard Medical School, told News 10 that despite the successful test results it's still too early to routinely treat patients with Opdivo.