CHICAGO — Replacing paclitaxel with nab-paclitaxel in an anthracycline regimen failed to significantly improve the pathologic complete response rate in patients with HER2-negative breast cancer, according to research presented at the 2016 American Society of Clinical Oncology (ASCO) Annual Meeting.1
“Sequential anthracycline and taxane regimens are a reference adjuvant therapy for high-risk breast cancer,” said lead investigator Luca Gianni, MD, medical oncologist at San Raffaele Scientific Institute in Milano, Italy. “In the sequence, weekly paclitaxel is superior to a taxane every 3 weeks.”
Neoadjuvant chemotherapy regimens with a taxane followed by an anthracycline doubled pathologic complete response rates, and the reverse sequence is at least equally effective. Because nab-paclitaxel, an albumin-bound nanoparticle formulation of paclitaxel that allows for safe infusion with premedication, is associated with a significantly higher pathologic complete response rate compared with paclitaxel in the neoadjuvant setting,2 investigators decided to compare outcomes after neoadjuvant nab-paclitaxel with paclitaxel followed by an anthracycline-based regimen in a phase 3 trial.
In the multicenter, open-label ETNA trial, researchers enrolled 695 patients with centrally confirmed HER2-negative breast cancer and randomly assigned them to receive paclitaxel 90 mg/m2 or nab-paclitaxel 125 mg/m2 on weeks 1, 2, and 3, followed by a 1-week rest, for 4 cycles. All patients then received an anthracycline-based regimen per investigator choice.
Results showed that the pathologic complete response rate was 18.6% (95% CI, 14.7-23.1) with paclitaxel vs 22.5% (95% CI, 18.2-27.3) with nab-paclitaxel (OR, 0.77; 95% CI, 0.52-1.13; P=.1858).
“The improved rate of pathologic complete response rate after nab-paclitaxel did not reach statistical significance,” Dr Gianni noted.
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In addition, multivariate analyses demonstrated that tumor subtype was most significantly associated with treatment outcome (OR, 4.85).
In terms of safety, the protein-bound paclitaxel was associated with a higher overall rate of grade 3 or worse peripheral neuropathy, neutropenia, fatigue, and vomiting compared with paclitaxel.
Dr Gianni concluded that extensive collection and banking of tumor (>90%) and blood were performed and translational studies might provide clues for informative correlations with available clinical findings.
- Gianni L, Mansutti M, Anton A, et al. ETNA (Evaluating Treatment with Neoadjuvant Abraxane) randomized phase III study comparing neoadjuvant nab-paclitaxel (nab-P) versus paclitaxel (P) both followed by anthracycline regimens in women with HER2-negative high-risk breast cancer: A MICHELANGO study. J Clin Oncol. 2016; 34 (suppl; abstr 502).
- Untch M, Jackisch C, Schneeweiss A, et al. Nab-paclitaxel versus solvent-based paclitaxel in neoadjuvant chemotherapy for early breast cancer (GeparSepto-GBG 69): a randomised, phase 3 trial. Lancet Oncol. 2016;17(3):345-56. doi:10.1016/S1470-2045(15)00542-2.