Could a new drug just approved by the U.S. Food and Drug Administration be the miracle cure some lung cancer patients have been waiting for?

The FDA approved the expanded use of Pfizer’s Xalkori, which is aimed at treating non-small cell lung cancer (NSCLC) in patients who have a specific mutation of a gene called ROS1, according to Pfizer and FDA statements.

It’s a fairly rare mutation, accounting for about 1 percent of NSCLC patients.

Xalkori is taking orally and blocks the ROS1 protein from mutating in the tumors, stopping it from growing and spreading.

The FDA approved the drug in 2011 for NSCLC patients who had the mutation of the anaplastic lymphoma kinase (ALK) gene, which makes up 4 percent of NSCLC patients.

Even though these types of mutations make up a small number of lung cancer patients, it’s a big deal not only for those patients who suffer from it but from a pure numbers statement, as lung cancer is the leading cuase of cancer-related deaths int he United States at 158,040 reported in 2015, so even 1 percent accounts for well over a thousand deaths.

“Lung cancer is difficult to treat, in part, because patients have different mutations, some of which are rare,” Richard Pazdur, M.D., director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, said in a statement. “The expanded use of Xalkori will provide a valuable treatment option for patients with the rare and difficult to treat ROS-1 gene mutation by giving health care practitioners a more personalized way of targeting ROS-1 positive NSCLC.”