How effective is tucatinib in shrinking tumors?

Tucatinib can shrink tumors under certain conditions. Tucatinib is an oral, small-molecule tyrosine kinase inhibitor that specifically targets HER2-positive tumors. HER2 (human epidermal growth factor receptor 2) is a transmembrane tyrosine kinase receptor that is overexpressed or genetically mutated in a variety of tumors and is closely related to the occurrence, development and prognosis of tumors. Tucatinib inhibits the tyrosine kinase activity of the HER2 receptor and blocks the conduction of the HER2 signaling pathway, thereby inhibiting the proliferation and migration of tumor cells.

In the HER2CLIMB clinical trial, tucatinib was combined with trastuzumab and capecitabine to treat HER2positive metastatic breast cancer, the progression-free survival (PFS) and overall survival (OS) are significantly prolonged.

For patients with brain metastases, the addition of tucatinib significantly reduced the risk of disease progression or death.

In the MOUNTAINEER clinical trial, tucatinib was combined with trastuzumab to treat patients with HER2-positive metastatic colorectal cancer. The results of the study showed that the objective response rate (ORR) of patients in the dual-targeted therapy group reached 38.1%, which means that nearly 40% of patients had their tumors significantly shrunk by 30% or even disappeared.

In addition, the therapy also significantly prolonged the patients' median progression-free survival (PFS) and median overall survival (OS).

Although tucatinib has shown remarkable efficacy in tumor treatment, its safety and tolerability are also the focus of clinical attention. Clinical trials have shown that tucatinib may cause some side effects, such as diarrhea, fatigue, nausea, rash, fever, etc. However, most of these side effects are mild to moderate and can be effectively managed with dose adjustment and supportive care. In addition, tucatinib has relatively low cardiotoxicity, which is particularly important for patients requiring long-term treatment.

References:

https://www.cancer.gov/news-events/cancer-currents-blog/2020/tucatinib-trastuzumab-deruxtecan-her2-positive-metastatic-breast-cancer