Pathologic complete response (pCR) rates in hormone receptor (HR)-positive, HER2-positive breast cancer were unchanged by the addition of an aromatase inhibitor (AI) to neoadjuvant docetaxel, carboplatin, trastuzumab and pertuzumab, according to findings from a phase 3 clinical trial presented at the 2016 San Antonio Breast Cancer Symposium.1
“At this point, we cannot recommend a change to the standard-of-care neoadjuvant treatment regimen for patients with HR-positive, HER2-positive breast cancer,” reported Mothaffar F. Rimawi, MD, of the Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas.
“There had been concern that chemotherapy and endocrine therapy may have opposing, antagonistic effects,” he noted. “We did not see that.”
A total of 308 patients with operable, locally-advanced HR-positive, HER2-positive breast cancer were randomly assigned to receive neoadjuvant docetaxel, carboplatin, trastuzumab and pertuzumab (TCHP), with or without an aromatase inhibitor (308 patients and 154 patients, respectively).
pCR of breast and nodal tumors for the TCHP-only and TCHP+AI study arms was 40.9% and 46.1% (P = 0.36), respectively, Dr Rimawi reported; breast tumor pCR was 44.2% and 47.4%, respectively (P = 0.57).
Grade 3/4 adverse event rates were similar between the 2 study arms, and included diarrhea, vomiting, and febrile neutropenia.
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“Discovering which patients need more therapy and which patients need less is crucial,” Dr Rimawi said.
The team is studying whether particular patient subgroups might benefit from adding an AI to neoadjuvant therapy.
- Rimawi MF, Cecchini RS, Rastogi P, et al. A phase III trial evaluating pCR in patients with HR+, HER2-positive breast cancer treated with neoadjuvant docetaxel, carboplatin, trastuzumab, and pertuzumab (TCHP) +/- estrogen deprivation: NRG Oncology/NSABP B-52. Paper presented at: 39th San Antonio Breast Cancer Symposium; Dec 2016; San Antonio, TX.