FDA Approves Vitrakvi as New Oncology Drug

On Monday, November 26th, 2018, the U.S. Food and Drug Administration (FDA) announced the approval of a new oncology medication, Vitrakvi (larotrectinib). This drug is the second approved medication in a class of immune therapies that treats cancers based on the biomarkers of the tumor rather than on the location of the tumor. Vitrakvi is the first type of drug that is considered “tissue agnostic,” which means that it is able to treat multiple types of cancers as long as they share the same, targeted biomarker.

Vitrakvi is used to treat both pediatric and adult solid-tumor cancers (not blood cancers) that have a neurotrophic receptor tyrosine kinase (NTRK) gene fusion without a known acquired resistance mutation. To qualify for this treatment, the cancer must have metastasized, or it should be in a place in the body where surgery to remove the tumor could cause harm. The drug should be used when there are no other treatment options available when first diagnosed, or when the patient has progressed following other therapies, such as a relapse.

About NTRK mutations

When NTRK genes become attached to other genes, they can send out signals that make tumors grow. This process is not common, but can happen in many different areas of the body, such as the lung, soft tissues, kidney, breast and thyroid. This is the first medication that has been approved to treat this specific NTRK gene mutation, and is a breakthrough in approvals for tissue agnostic therapies.

About Vitrakvi

Vitrakvi was tested in three separate clinical trials in both pediatric and adult patients. There were 55 patients treated with the medication who had the NTRK gene, and either had no other good treatment options, or had relapsed. There was a 75% overall response rate, which was not limited to any of the types of solid tumors. In the time beyond that, 73% of responses lasted more than six months, and 39% of responses lasted over a year. There were many different types of tumors that responded to the medication, including, lung, thyroid, salivary gland, soft tissue sarcomas, and infantile fibrosarcoma.

Accelerated approval

Because the patients were treated so successfully, and there are not other drugs that treat NTRK gene mutations, Vitrakavi received an accelerated approval from the FDA. This approval is specifically for drugs that fill an unmet medical need, whose research has shown that it has a clinical benefit for patients. This drug will continue to undergo research to show that the clinical benefit can be confirmed.

Possible side effects with Vitrakvi

Like most drugs, Vitrakvi causes some side effects. The most common side effects reported in the clinical trials were fatigue, nausea, cough, constipation, diarrhea, vomiting, dizziness and increased liver enzyme levels (ALT and AST). Patients should report symptoms of dizziness to their doctor right away, as they can be signs of neurological reactions. Patients should also have their ALT and AST levels checked every two weeks for the first month of treatment, then once a month as clinically indicated.

Why this is important

This approval of this drug is important because it means that physicians and researchers are treating cancer by looking at tumor genetics, which means that the treatments are becoming much more targeted to the specific tumor. This approval paves the way for researchers to study other targeted therapies that may treat multiple cancers rather than cancers by locations within the body, giving patients better treatment, and more effective therapy.

View References
  1. FDA approves an oncology drug that targets a key genetic driver of cancer, rather than a specific type of tumor. U.S. Food and Drug Administration. Available at https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm626710.htm. Published 2018. Accessed November 28, 2018.

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