By james art Tucatinib and trastuzumab work by blocking a protein known as human epidermal growth factor receptor 2 (HER2) in cancer cells to stop them from growing or spreading.
The drugs are recommended by the National Institute for Health and Care Excellence (Nice) as an option for patients with HER2-positive locally advanced or metastatic breast cancer who have had two or more anti-HER2 therapies.
Researchers have explored using the treatment for other types of cancer, including bile duct cancer.
Bile duct cancer, also known as cholangiocarcinoma, affects the small tubes that connect various organs, including the liver and gallbladder.
The phase two study included 217 patients with various tumors that had spread throughout the body and had signs of HER2 changes.
They were given 21-day cycles of tucatinib tablets twice daily and intravenous trastuzumab once every three weeks.
The researchers found that the cancer shrank in 22.2% of patients overall. However, among the 30 patients with bile duct cancer, the cancer decreased by 46.7%.
Dr Yoshiaki Nakamura, of the National Cancer Center East Hospital in Kashiwa, Japan, said: “This chemotherapy-free combination has been shown to be safe and well tolerated. Very few patients had to stop treatment due to side effects.
“The results of the study show variable effects in different tumor types.
“However, patients with HER2-positive metastatic biliary tract cancer and HER2-mutated metastatic breast cancer had clinically meaningful overall response rates.
“These results support the inclusion of this drug combination in the guidelines for patients with previously treated HER2-positive biliary tract cancer.”
“The results for patients with metastatic breast cancer suggest that those with HER2-mutated tumors may also benefit from these HER2-targeted treatments.”
According to Liver Cancer UK, around 2,200 people in England are diagnosed with bile duct cancer each year.
The results of the study will be presented at the EORTC-NCI-AACR Symposium on Molecular Targets and Cancer Therapy in Barcelona on Thursday.
Dr. Tim Gretten, co-chair of the EORTC-NCI-AACR symposium and senior investigator at the National Cancer Institute’s Center for Cancer Research, added: “Cancer research often focuses on a particular type of tumor, such as breast or bowel cancer.
“This trial is designed to focus on the molecular makeup of the tumor, no matter where it is in the body.
“This means researchers can target rare forms of the disease, such as bile duct cancer, that urgently need more treatment options.”
“HER2 has been well studied in breast cancer, but we are beginning to see that it may be a useful target for the treatment of other cancers.
“This study suggests that using two drugs that target HER2 may prove beneficial for a wider group of breast cancer patients and for some patients with biliary tract cancer. However, this is an early experience and we need to see further research to confirm these results.