Precautions for tucatinib

Tucatinib can treat advanced unresectable or metastaticadult patients with HER2-positive breast cancer, RAS wild-type, and HER2-positive unresectable or metastatic colorectal cancer. During use, attention should be paid to the occurrence of adverse events such as diarrhea and hepatotoxicity. Women of reproductive potential need to adjust the dose according to medical advice.

1. Diarrhea: Tucatinib may cause severe diarrhea, including dehydration, hypotension, acute kidney injury and death. Diarrhea occurred in 81% of patients receiving tucatinib, including Grade 4 diarrhea in 0.5% and Grade 3 diarrhea in 12%. Two patients who developed grade 4 diarrhea subsequently died, and diarrhea was a cause of death. Depending on the severity of the diarrhea, dose interruption was followed by dose reduction or permanent discontinuation of tucatinib.

2. Hepatotoxicity: 8% of patients who received tucatinib had ALT elevation >5×ULN, 6% of patients had AST elevation >5×ULN, and 1.5% had bilirubin elevation >3×ULN. Hepatotoxicity resulted in tucatinib dose reduction in 8% of patients and tucatinib discontinuation in 1.5% of patients.

3. Embryo-fetal toxicity: According to the results of animal studies and its mechanism of action, tucatinib taken by pregnant women can cause harm to the fetus. In animal reproduction studies, when maternal exposure≥ Administration of tucatinib to pregnant rats and rabbits during organogenesis caused embryonic fetal death, reduced fetal weight, and fetal malformations at 1.3 times the recommended human exposure (AUC).

According to the original drug of Tucatinib, it has not yet been launched in China, so it has not been covered by domestic medical insurance. The price of the European version of Tucatinib, which is available overseas, is around 72,000 yuan (the price may fluctuate due to the exchange rate), which is expensive. There are also generic drugs of tucatinib produced in other countries. The price produced by Laos pharmaceutical factory is around 6,400 yuan (the price may fluctuate due to the exchange rate). The ingredients of foreign generic drugs are basically the same as the original drugs.