New drug shows promise for some cancer types

While doctors most often receive information about new drugs from their professional societies and pharmaceutical representatives, every now and then, we get blind-sided. Such was the case recently with an oral drug I would soon learn was called Vitrakvi.

In the same day, one patient I was seeing and a couple of others via phone asked if I was aware of a new drug that was curing cancer. They had seen a report on the nightly news. While they could not recall the name of the drug or the specifics of what cancers were benefitted, I clearly had an assignment to learn more.

Turns out, the drug is larotrectinib (brand name Vitrakvi). Medically speaking, it inhibits a specific tyrosine kinase (an enzyme) signal that makes a normal cell act like a cancer cell. The specific tyrosine kinase is encoded by DNA at a gene locus known as NTRK. In some cancers, this gene is mutated.

Unfortunately, in the more common cancer subtypes, this gene is not mutated; therefore, the drug is ineffective. However, the mutation has been found—and the drug shown effective—in cancers of the salivary and thyroid glands, some lung cancers and some sarcomas.

More and more frequently, cancer specialists are sending cancer tissue for mutation analysis by what is known as Next Generation Sequencing. In this way, these specialists determine mutations present in the cancer cells, including some deemed to be “driver” mutations, which can be targeted by drugs such as larotrectinib. This new drug is only the second therapy approved by the FDA for biomarker-positive patients across all solid tumor types.

The drug and its treatment were approved via an accelerated approval based on overall response rate and duration. Continued approval for its indication (namely, treatment of tumors with NRTK gene mutation) is contingent on verification of benefit in confirmatory trials.

Of course, while not emphasized in the news report, the drug has side effects including fatigue, nausea and other GI complaints, dizziness, and liver and nerve toxicity. I have not been able to find an accurate quote as to the cost, but it likely may produce financial toxicity as well!

In summary, this new drug can help patients who have a cancer bearing a specific gene mutation. I am ecstatic to have it, and although it is unlikely to help a large number of patients, I hope it proves to be a wonderful therapy for those with this specific gene mutation.

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