The Food and Drug Administration has approved the first drug for a specific mutation causing lung cancer in adults who have undergone at least one systemic treatment, such as chemotherapy.

U.S. regulators approved a 960 milligram dose of Lumakras (sotorasib) to battle non-small cell lung cancer with tumors involving a genetic mutation called KRAS G12C. The accelerated approval stemmed from modeling and a study involving 124 lung cancer patients with the specific mutation. Researchers were assessing whether the treatment destroyed or reduced patients’ tumors and the duration of response. Results indicated 36% of patients benefited from treatment and 58% saw responses lasting for at least six months.

KRAS mutations are blamed for about 25% of non-small cell lung cancers, and KRAS G12C mutations comprise some 13% of mutations in non-small cell lung cancers, per the FDA.

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"KRAS mutations have long been considered resistant to drug therapy, representing a true unmet need for patients with certain types of cancer," Dr. Richard Pazdur, director of the FDA’s Oncology Center of Excellence and acting director of the Office of Oncologic Diseases in the FDA’s Center for Drug Evaluation and Research, said in a statement posted Friday. "Today’s approval represents a significant step towards a future where more patients will have a personalized treatment approach."

Lung cancer is the third most common cancer in the U.S., according to the Centers for Disease Control and Prevention (CDC), and it is associated with the highest mortality among both sexes compared to other cancers. The FDA says lung cancer can be characterized by the genetic mutations behind it. KRAS for instance "is a type of mutation in a group of genes that help regulate cell growth and division," the agency wrote.

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The treatment was granted accelerated approval, and requires an additional trial to assess whether a lower dose could result in the same clinical effect. Common side effects include diarrhea, musculoskeletal pain, nausea, fatigue, liver damage and cough, according to the FDA. Providers should halt treatment upon suspected interstitial lung disease, and end treatment if the disease is confirmed.

Providers were advised to monitor patients' liver function during treatment, and adjust or stop treatment upon liver damage. While on treatment, patients should avoid taking acid-reducing agents, or drugs involving enzymes in the liver, the FDA advised.