On November 26, the FDA approved Vitrakvi (larotrectinib, Loxo Oncology, Inc.) for the treatment of tumors that have no known resistance mutation, are metastatic, or where surgical resection would likely result in severe morbidity.
This “tissue agnostic” drug marks the second time the agency has approved a cancer treatment based on tumor genetics rather than the site of origin in the body.
NTRK genes can fuse to other genes abnormally, resulting in signals that support tumor growth. While rare, NTRK fusions occur in cancers that arise in many areas of the body. Larotrectinib is the first treatment available for cancers that frequently express this mutation, such as mammary analogue secretory carcinoma, cellular or mixed congenital mesoblastic nephroma, and infantile fibrosarcoma.
In clinical trials, larotrectinib showed a 75 percent overall response rate across different types of solid tumors, including soft tissue sarcoma, salivary gland cancer, infantile fibrosarcoma, thyroid cancer, and lung cancer. Seventy-three percent of responses lasted at least six months, and 39 percent lasted one year or more. Tumor types that responded to the drug included soft tissue sarcoma, salivary gland cancer, infantile fibrosarcoma, thyroid cancer and lung cancer.
Common side effects included fatigue, nausea, cough, constipation, diarrhea, dizziness, vomiting, and increased AST and ALT enzyme blood levels in the liver. Women who are pregnant or breastfeeding should not take Vitrakvi as it may harm the developing fetus or newborn baby.
The FDA granted Vitravki priority review, breakthrough therapy, and orphan drug designations.
Source: Drugs.com, November 26, 2018, https://bit.ly/2SdWC41