CHICAGO — The combination of pyrotinib and capecitabine significantly prolonged PFS among patients with HER2-positive metastatic breast cancer compared with placebo, according to study results presented at the ASCO Annual Meeting.
“For HER2-positive breast cancer, anti-HER2 treatment is a standard care,” Zefei Jiang, MD, from the Fifth Medical Center of Chinese PLA General Hospital in Beijing, China, said during his presentation.
There has been great progress in neoadjuvant and adjuvant care, but trastuzumab (Herceptin, Genentech) remains the primary therapy, according to Jiang. Pyrotinib is a new drug that targets the epidermal growth factor receptor and has shown promising results in prior trials in terms of tolerability and antitumor activity, he continued.
Jiang and colleagues conducted a double-blind, multicenter, phase 3 study to examine the efficacy of pyrotinib plus capecitabine compared with placebo plus capecitabine in patients with HER2-positive metastatic breast cancer who were treated with taxanes and trastuzumab prior to the study.
The researchers randomly assigned 279 participants 2:1 to receive 400 mg pyrotinib or placebo orally once a day for 21-day cycles plus 1,000 mg/m² capecitabine orally twice a day on days 1-14.
The primary endpoint was PFS as determined by an independent review committee and was evaluated in patients who received one or more doses of the study drug. If disease progression was observed in patients receiving placebo plus capecitabine, they were switched to single-agent pyrotinib.
The median PFS was longer among patients receiving the combination of pyrotinib and capecitabine (11.1 months; 95% CI, 9.66-16.53) than those receiving the combination of placebo and capecitabine (4.1 months; 95% CI, 2.79-4.17).
Subsequent pyrotinib was administered in 71 out of 94 patients in the placebo plus capecitabine arm. These patients had a single-agent response rate of 38% (95% CI, 26.7%-49.3%) and a median PFS of 5.5 months (95% CI, 4.07-6.9).
Diarrhea and hand-foot syndrome were the most common treatment-related adverse events of grade 3 or higher and occurred more often in patients treated with pyrotinib than placebo (30.8% vs. 12.8% for diarrhea and 15.7% vs. 5.3% for hand-foot syndrome).
Overall, however, combination treatment with pyrotinib and capecitabine was well tolerated, Jiang said.
“Pyrotinib plus capecitabine can significantly improve median PFS versus placebo plus capecitabine in women with HER2-positive metastatic breast cancer after treatment with trastuzumab and a taxane,” he concluded. “Patients who progress on capecitabine could benefit from pyrotinib treatment as a single agent.” – by Alaina Tedesco
Jiang Z, et al. Abstract 1001. Presented at: ASCO Annual Meeting; May 31-June 4, 2019; Chicago.
Disclosures: Jiang reports no relevant financial disclosures. Please see the abstract for all other authors’ relevant financial disclosures.