Novel 4-Drug Combo Significantly Improves Treatment Responses in Group of Patients with Breast Cancer

The use of pyrotinib combined with the chemotherapies trastuzumab, docetaxel and carboplatin (TCbH) was associated with a significantly improved complete response rate in patients with HER2-positive breast cancer, compared to treatment with triplet chemotherapy combination.

“In this study, TCbH plus pyrotinib neoadjuvant therapy significantly improved the total (complete response) rate of HER2-positive breast cancer patients for about twice (that of) TCbH with a manageable safety (profile),” the study authors wrote.

The data, which were recently presented at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting, included 67 patients who were randomized into either treatment group.

The aim of the study was to evaluate the efficacy and safety of the addition of pyrotinib, an irreversible second-generation HER2-targeted tyrosine kinase inhibitor (TKI), to TCbH versus TCbH alone given as neoadjuvant (pre-treatment therapeutics) treatment in patients with stage 2-3 HER2-positive breast cancer and invasive carcinoma.

Measuring pathologic complete response (defined as no evidence of invasive or in situ disease in the breast or axilla [armpit]) was the main goal of the study. Additional goals included assessing toxicity, event-free survival (time after primary treatment ends that a patient stays free of complication or events that the treatment was supposed to prevent or delay), disease-free survival (the time after treatment without signs of cancer) and objective response rate (percentage of patients with partial and complete responses to the treatment).

From 2019 to 2021, 67 patients with HER2-positive breast cancer were randomized equally into the pyrotinib group or TCbH alone group. Investigators hypothesized that patients treated in the pyrotinib plus TCbH group could have a higher complete response rate than the group that received the triple chemo combination alone. Their hypothesis proved true with the total complete response rate in the treatment group measuring 71.4% versus 36.7% in the TCbH group.

Thirty-four patients received the four-drug combination. As of data cutoff, 21 patients had undergone surgery, seven had not completed treatment, and six withdrew consent and discontinued treatment. Of the 33 patients who received the triplet chemotherapy regimen without pyrotinib, 30 had undergone surgery and three had not completed neoadjuvant therapy.

All the 21 patients in the pyrotinib group who proceeded to surgery achieved a response, while 83.3% of those who received the chemotherapy alone and proceeded to surgery achieved a response.

The most common side effect was diarrhea, with serious events occurring in six cases (28.6%) in the treatment group, most of which were limited to the first treatment cycle. In the control group, three patients (10%) experienced serious diarrhea.

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