What should I do if I become resistant to Trastuzumab?

HER2 is a transmembrane oncoprotein encoded by the HER2/neu gene and is overexpressed in approximately 20-25% of invasive breast cancers. It can be targeted by treatment with trastuzumab, and while trastuzumab is currently considered one of the most effective treatments in oncology, a large number of patients with HER2-overexpressing breast cancer do not benefit from it.

Trastuzumab is used at clinical doses thought to produce receptor saturation. In a phase I trial, the mean maximum plasma concentration of trastuzumab was approximately 70 μg/mL when 22 patients received a conventional 4 mg/kg loading dose followed by 2 mg/kg weekly doses. For patients who develop trastuzumab resistance due to interference with trastuzumab binding, strategies to overcome resistance may include the use of treatments that do not rely on binding to HER2 extracellular domain molecules, including the use of TK inhibitors, such as lapatinib, or inhibitors of HER2 downstream signaling pathways. However, everyone’s physique is different and their resistance to drugs is also different. If you feel unwell, please inform your doctor in time.

Trastuzumab is sold under the brand name Herceptin in China and has entered the scope of Class B medical insurance, but it may be limited to patients who meet the indications for this drug, such as patients with HER2-positive metastatic breast cancer and its adjuvant and neoadjuvant treatment or HER2-positive metastatic gastric cancer. The price is around 6,000 yuan. The original trastuzumab drug has also been launched overseas. The drug ingredients of domestic and foreign original drugs are basically the same. For specific prices and drug details, you can consult the medical consultant. There is currently no generic drug of trastuzumab on the market.