When to Use Targeted Therapy for Iodine-Refractory Thyroid Cancer

Krzysztof J. Misiukiewicz, MD, associate professor of hematology and medical oncology at the Icahn School of Medicine at Mount Sinai and clinical director of the Center for Personalized Cancer Therapeutics at the Tisch Cancer Institute, discusses when targeted therapy may be used for patients with NTRK-positive thyroid cancer.

Misiukiewicz says that patients with thyroid cancer will first receive surgery and/or radioactive iodine therapy. Those who continue to progress following total thyroidectomy and receiving radioactive iodine need further treatment. Genetic testing can reveal potential targets for therapy including RET, BRAF V600E, and NTRK, which have different recommended regimens.

Those who have an NTRK fusion, are iodine-refractory, and have no alternative treatment options are eligible for the NTRK inhibitors larotrectinib (Vitrakvi) and entrectinib (Rozlytrek). These therapies are approved for patients with any solid tumor with an NTRK fusion, which can also include salivary gland tumors and soft tissue sarcoma.

According to Misiukiewicz, larotrectinib would be his preferred next line of therapy for any patient with iodine-refractory thyroid cancer with an NTRK fusion based on the efficacy seen with NTRK inhibition.

TRANSCRIPTION:

0:08 | In thyroid cancer, we treat patients [who] are iodine-refractory, meaning that they underwent total thyroidectomy; they underwent treatment with radioactive iodine and for any reason, those treatments were not effective, and the cancer is still progressing, so we label those patients as iodine-refractory patients. In those situations, those patients are being referred to me, where I do first genetic testing. And then I would consider treating those patients with larotrectinib. So they have to have evidence of progressive cancer that hasn't responded to previous treatments such as surgery or radioactive iodine.

Whenever I have [patients with] the NTRK-positive disease, I prefer targeted therapy. Currently we have 2 drugs on the market that are approved; my preferred drug is larotrectinib. That is approved for NTRK-mutated patients. And this is the drug that usually I choose when I have patients with the NTRK-positive mutation.