Tucatinib/tucatinib Chinese usage guide

1. Main treatment areas:

1) Treatment of metastatic breast cancer (MBC): Tucatinib, also known as tucatinib, when used in combination with trastuzumab and capecitabine, is particularly indicated for the treatment of patients with advanced unresectable or metastatic HER2-positive breast cancer who may have experienced one or more prior anti-HER2-based treatment regimens, even those who have developed brain metastases.

2) Treatment of unresectable or metastatic colorectal cancer (CRC): For adult patients with RAS wild-type, HER2-positive, unresectable or metastatic colorectal cancer, if their disease still progresses after chemotherapy with fluoropyrimidine, oxaliplatin and irinotecan, the combination treatment of tucatinib and trastuzumab will be an effective option.

2. Medication Guide:

1) Patient screening: For patients with unresectable or metastatic colorectal cancer, before choosing to use tucatinib, they should be confirmed to have HER2 overexpression or gene amplification and be RAS wild-type.

2) Recommended dosage: Patients should take tucatinib twice a day, 300mg each time until the disease progresses or drug toxicity reaches an unacceptable level. When used in combination with trastuzumab and capecitabine, the recommended dose of capecitabine is 1000 mg/m² twice daily, taken within 30 minutes after a meal. All medications should be administered in accordance with relevant clinical guidelines.

3) Medication precautions: Patients should swallow tucatinib whole and do not chew, crush or split the tablets. Tablets should not be taken if they are broken, cracked, or incomplete. The two doses should be taken approximately 12 hours apart and have nothing to do with meal times. If the patient vomits or misses a dose, the next dose can be taken at the scheduled time.

4) Dose adjustment: Based on adverse reactions, doctors may adjust the dose of tucatinib, which can be reduced to 250 mg twice a day for the first time, 200 mg twice a day for the first time, 200 mg twice a day for the first time, and finally 150 mg twice a day. For patients unable to tolerate the 150 mg dose, the drug should be permanently discontinued.

Patients with severe liver impairment should reduce to 200mg twice daily At the same time, concurrent use with strong CYP2C8 inhibitors should be avoided. If this cannot be avoided, tucatinib should be reduced to 100 mg twice daily. After stopping the inhibitor, the previous dose should be resumed.

3. Possible side effects:

atIn patients with MBC, common side effects include diarrhea, paresthesias in the palms and soles of the feet, nausea, liver damage, vomiting, mouth ulcers, decreased appetite, anemia, and rash. For patients with CRC, common side effects include diarrhea, fatigue, rash, nausea, abdominal pain, infusion reactions, and fever. In addition, laboratory tests may reveal increases in creatinine, glucose, transaminases and other indicators, as well as decreases in hemoglobin and lymphocytes.

4. Drug storage recommendations:

Tucatinib is available in tablet form and should be stored at room temperature (20°C to 25°C) and allowed to fluctuate within the range of 15°C to 30°C. Medications should be stored in their original containers to protect them from moisture and tightly closed after each use. Desiccant should not be discarded and once opened, medicines should be used within 3 months and any unused tablets should be discarded 3 months after opening.

5. Drug action mode:

Tucatinib is aHER2 tyrosine kinase inhibitor. In a laboratory setting, it inhibits the phosphorylation process of HER2 and HER3, thereby blocking downstream MAPK and AKT signaling, inhibiting excessive cell proliferation, and showing anti-tumor effects in HER2-expressing tumor cells. In vivo, tucatinib can effectively inhibit the growth of HER2-expressing tumors. Tucatinib in combination with trastuzumab has shown greater antitumor activity in the laboratory and in vivo than trastuzumab alone.