Predicting Complete Response in ERBB2-Positive Breast Cancer

In a recent study, published in JAMA Oncology, researchers evaluated whether the HER2DX assay could predict pathological complete response (pCR) in patients with early-stage ERBB2-positive breast cancer after neoadjuvant therapy. The authors suggested the ability to predict pCR may improve neoadjuvant treatment optimization.

According to the study’s lead author, Adrienne Waks, analysis of diagnostic and prognostic data indicated that the HER2DX assay pCR score could predict pCR after deescalated neoadjuvant treatment with paclitaxel, trastuzumab, and pertuzumab in patients with newly diagnosed stage II to III ERBB2-positive breast cancer.

The study assessed pretreatment tumor biopsy samples from 80 of 97 (82.5%) patients ERBB2-positive breast cancer in the phase 2 DAPHNe clinical trial. The cohort was 98.8% female and had a mean age of 50.3 years (range, 26.0-78.0).

Participants received neoadjuvant paclitaxel once weekly plus trastuzumab and pertuzumab every 3 weeks over 12-week cycles, with 4 cycles in total. The primary end point of this analysis was a likelihood score from 0-100 to predict pCR .

HER2DX Predicts Response in ERBB2-Positive Breast Cancer

Researchers found HER2DX pCR score was significantly associated with pCR in their patients (odds ratio [OR], 1.05; 95% CI, 1.03-1.08; P<.001). Furthermore, high-, medium-, and low-risk groups stratified by pCR score had pCR rates of 92.6%, 63.6%, and 29.0%, respectively (high vs low OR, 30.6; P<.001).

Notably, this association was independent of hormone receptor status, ERBB2 immunohistochemistry score, HER2DX ERBB2 expression score, and microarray 50 ERBB2-enriched subtype prediction analysis.

The report noted HER2DX pCR score had a weak correlation with a prognostic risk score, though investigators added they could not assess the risk score’s performance due to a lack of recurrence cases.

Overall, the authors concluded that the HER2DX assay was able to predict pCR in patients with early-stage ERBB2-positive breast cancer after deescalated neoadjuvant therapy. They suggested that “the HER2DX pCR score might guide therapeutic decisions by identifying patients who are candidates for deescalated or escalated approaches.”

Related: HER2-Positive Breast Cancer: 10-Year Paclitaxel and Trastuzumab Survival