What should I do if I develop drug resistance after taking trifluridine and tipiracil tablets (Lonsurf)?

Lonsurf, trifluridine tipiracil tablets (Lonsurf), is a fixed-dose combination drug used as a third- or fourth-line treatment for metastatic colorectal or gastric cancer after failure of chemotherapy and targeted therapy. It is a combination of two active pharmaceutical ingredients: the nucleoside analog trifluridine and the thymidine phosphorylase inhibitor tipiracil. Tipiracil prevents the rapid metabolism of trifluridine and increases the bioavailability of trifluridine.

The most common side effects of trifluridine and tipiracil include neutropenia, nausea, fatigue, and anemia. If the patient fails to respond to treatment after use, drug resistance testing can be performed to confirm whether drug resistance has indeed occurred. By analyzing tumor tissue samples or blood samples, relevant drug-resistant gene mutations or changes in expression levels can be detected. This can help determine if treatment strategies need to be adjusted. In cases of drug resistance, combination treatment strategies may be considered. That is, trifluridine tipiracil tablets can be used in combination with other drugs to enhance the therapeutic effect. For example, it can be combined with chemotherapy, targeted therapy, immunotherapy and other methods in order to obtain better curative effects.

The original drug of trifluridinetipiracil tablets has been marketed in China under the trade name Langsif, but it has not yet entered the scope of medical insurance. The price per box may be around RMB 6,000, and the price per box of the Hong Kong version may be more than RMB 10,000 (the price may fluctuate due to exchange rates). The Japanese version of trifluridine tipiracil tablets sold overseas may cost around more than 5,000 yuan per box (the price may fluctuate due to exchange rates). There are also cheaper generic versions of trifluridine and tipiracil tablets available overseas. Their pharmaceutical ingredients are basically the same as those of the original drugs sold domestically and abroad. For example, the price of each box produced by an Indian pharmaceutical factory may be around more than 1,000 yuan (the price may fluctuate due to exchange rates).