Presented at the most recent Annual Meeting of the American Thyroid Association (ATA) in Washington, Larotrectinib has drawn a lot of attention by becoming the latest form of therapy for cases of non-medullary thyroid cancer.
This is not the first time the drug made news, as earlier this year it was granted Priority Review by the FDA, only months after it had received Breakthrough therapy designation from the same agency.
Larotrectinib is an “oral and selective inhibitor of tropomyosin receptor kinases (TRK), a family of signaling proteins that play an important role in cellular communication and tumor growth”. When NTRK genes (which encode TRKs) abnormally fuse with other genes, they can lead to cancers. This drug was designed to target TRK, disrupting the signaling path that promotes the disease.
A small study conducted on patients with cancers that featured TRK fusions displayed an objective response rate of 75%. The trial involved 7 participants, all treated with 100mg doses of Larotrectinib twice a day, during a 28-day program. These were all subjects that had underwent surgery for thyroid removal. At the end of the project, there was one complete response and four cases of partial response. The duration of the response was between 1.9 and 18.8 months.
Overall, the drug is very well tolerated, more than 90% of all adverse events being only slight, the most common being dizziness, nausea, vomiting.
Another more extensive study revealed similar results and concluded that “TRK fusions defined a unique molecular subgroup of advanced solid tumors in children and adults in whom larotrectinib was highly active. Durable responses were observed without regard to the age of the patient, tumor tissue, and fusion status. The side-effect profile of larotrectinib suggests that long-term administration is feasible for patients