PFS was extended by nearly 6 months among patients who received pyrotinib, a novel pan-HER2 inhibitor, combined with capecitabine. Grade 3 diarrhea occurred in nearly 31% of patients receiving the pyrotinib-capecitabine combination, though none of the patients discontinued treatment due to this adverse event.
Binghe Xu, MD, PhD, of the National Cancer Center/Cancer Hospital at the Chinese Academy of Medical Sciences and Peking Union Medical College in Beijing,
The value of pyrotinib
Although there are already many targeted therapies for HER2-positive metastatic breast cancer, accessibility can be an issue, with drugs such as pertuzumab and trastuzumab emtansine (T-DM1) not available in all regions of the world, according to Dr. Xu.
“Before we initiated this clinical trial, lapatinib plus capecitabine was the only second-line standard of care against HER2-positive metastatic breast cancer in China,” he said.
Based, in part, on results of the PHOEBE trial, the combination of pyrotinib and capecitabine was approved in China as a second-line standard of care for patients with HER2-positive metastatic breast cancer, according to Dr. Xu.
Pyrotinib has now demonstrated “clinical value” in two phase 3 clinical trials, but its value in relation to pertuzumab, T-DM1, tucatinib, trastuzumab deruxtecan, or neratinib is less clear, said Aleix Prat, MD, PhD, of Hospital Clinic of Barcelona.
“Also, in my opinion, the toxicity profile needs attention,” Dr. Prat said in a discussion of the PHOEBE results that was also part of the virtual ASCO meeting.
The 31% incidence of grade 3 diarrhea was “very similar,” he said, to what was seen in PHENIX, another phase 3 trial of pyrotinib plus capecitabine that was presented at the 2019 ASCO annual meeting ().
“What is the current therapy landscape? In my opinion, today, the first line remains taxane, trastuzumab, and pertuzumab; the second line T-DM1; and the third line tucatinib, trastuzumab, and capecitabine, with other treatment strategies reserved for later lines,” Dr. Prat said.