Comparing the safety and effectiveness of pyrotinib versus trastuzumab etamsine for the treatment of HER2-positive metastatic breast cancer.

This study compared the safety and effectiveness between pyrotinib (SHR-1258) and trastuzumab emtansine (T-DM1; Kadcyla) in patients with HER2+ metastatic breast cancer (BC) after previous treatment with trastuzumab (Herceptin) and chemotherapy. The data showed that pyrotinib may be more effective than T-DM1 for these patients.

Breast cancer (BC) is classified into different subtypes depending on the presence or absence of certain receptors (proteins found on the surface of the cancer cells). HER2 (human epidermal growth factor receptor 2) is a protein that promotes the growth of some BC. This subtype of BC is called HER2-positive (HER2+) BC. Patients with metastatic HER2+ BC (that has spread to distant organs) have limited treatment options. Trastuzumab (Tra) is a targeted therapy drug used to treat metastatic HER2+ BC. However, some patients become resistant and stop responding to trastuzumab treatment.

Trastuzumab emtansine (T-DM1) is a drug similar to Tra used in patients with BC that have high levels of HER2. Previous studies have shown this drug to be associated with significantly longer time before disease progression and overall survival compared to a combination of capecitabine (Cap; Xeloda) and lapatinib (Lap; Tyverb).

Pyrotinib (Pyr) is a type of targeted therapy known as a tyrosine kinase inhibitor (TKI). It is a new drug that targets HER2 and stops the cells from growing and spreading. Pyrotinib plus capecitabine has been approved in China for HER2+ metastatic BC in patients who have received previous trastuzumab treatment. However, the safety and effectiveness of pyrotinib versus T-DM1 in patients with metastatic HER2+ BC after previous treatment with trastuzumab and chemotherapy remain under investigation.

This study analyzed 12 other studies involving a total of 4353 women with metastatic HER2+ BC. 9 treatment regimens were included in the analysis. These regimens were T-DM1 alone, Lap-Cap, Tra-Cap, Cap alone, neratinib (Ner; Nerlynx), pertuzumab (Per; Perjeta)-Tra-Cap, Pyr-Cap, atezolizumab (Ate; Tecentriq)-T-DM1, and Ner-Cap.

Patients who received Pyr-Cap had a 23% lower risk of cancer progression compared to patients who received T-DM1. The survival without cancer progression for patients who received Pyr-Cap was also more favorable than those who received Lap-Cap, Tra-Cap, Cap, Ner, Per-Tra-Cap, and Ner-Cap.

Patients who received Pyr-Cap had a better overall survival (OS) rate than those who received Lap-Cap, Cap, and Ner. Patients who received Pyr-Cap were 7.87 times more likely to respond better to treatment than Cap.

No significant difference was observed in side effects among all the regimens. Pyr-Cap treatment had the highest probability to be the best treatment regimen in terms of better survival without cancer progression (99.4%), OS (89.7%), response rate (86.4%), and severe side effects (89.3%).

This study concluded that pyrotinib may be more effective than T-DM1 for patients with HER2-positive metastatic BC after previous treatment with trastuzumab and chemotherapy. However, it may be associated with more side effects.

This study analyzed the results of multiple studies with different protocols. None of the studies directly compared the effectiveness and safety between pyrotinib and T-DM1. The results of this study need to be verified in future randomized controlled trials.