For the second time, the US Food and Drug Administration (FDA) has approved a drug to treat tumors with a specific genetic change regardless of the type of cancer. Vitrakvi (larotrectinib) is for adults and children with solid tumors that test positive for NTRK genes, which can help cancerous tumors grow. Tumors with this type of genetic change are not common but can be found in cancers of the salivary gland, thyroid, lung, and soft tissue sarcoma. The drug is to be used to treat tumors that have spread or can’t be surgically removed and that have grown during previous treatments.
This approval is a significant step in the development of cancer drugs that treat tumors based on the genetic properties of the tumor, rather than their location in the body. Last year, the FDA expanded the approval of Keytruda (pembrolizumab) to include treatment for adults and children with advanced solid tumors that have either high levels of microsatellite instability (MSI-H) or mismatch repair deficiency (dMMR).
"Today’s approval marks another step in an important shift toward treating cancers based on their tumor genetics rather than their site of origin in the body," said FDA Commissioner Scott Gottlieb, MD. "This new site-agnostic oncology therapy isn’t specific to a cancer arising in a particular body organ, such as breast or colon cancer. Its approval reflects advances in the use of biomarkers to guide drug development and the more targeted delivery of medicine. We now have the ability to make sure that the right patients get the right treatment at the right time.”
The FDA based its approval on 3 clinical trials that included 55 adults and children with several different cancer types, all with NTRK positive tumors. The patients’ tumors could not be removed through surgery or had gotten worse after treatment.
All the patients were given Vitrakvi, which comes in pill form. The overall response rate, which is the portion of patients whose tumors shrank, was 75%. The improvement lasted for at least 6 months in 73% of those who responded, and for at least a year in 39% of those who responded.
Vitrakvi was approved using several FDA approaches designed to speed up the availability of drugs to treat serious diseases – breakthrough therapy designation, priority review status, and accelerated approval. It was also granted orphan drug designation, which provides financial incentives to encourage the development of drugs for rare diseases.
Common side effects included fatigue, nausea and vomiting, cough, constipation, diarrhea, and dizziness. Regular blood tests are needed to check liver function. Women who are pregnant or breastfeeding should not take Vitrakvi. Patients should report signs of neurologic reactions such as dizziness.
Vitrakvi is marketed by Bayer and Loxo Oncology, Inc.
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