Similar Efficacy, Less Toxicity with Neoadjuvant Letrozole/Palbociclib Versus Chemo in Breast Cancer
Although there was less toxicity, neoadjuvant letrozole plus palbociclib had similar response and BCS rates when compared with chemotherapy.
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Neoadjuvant letrozole plus palbociclib, a CDK inhibitor, resulted in less toxicity but similar response and breast conserving surgery (BCS) rates compared with chemotherapy among women with luminal breast cancer, according to late-breaking abstract presented at the European Society of Medical Oncology (ESMO) 2017 Congress in Spain.
Neoadjuvant chemotherapy has had limited success in luminal breast cancer, and palbociclib plus endocrine therapy improves outcomes among women with advanced disease. The purpose of this trial was to determine the efficacy and safety of letrozole plus palbociclib in the neoadjuvant setting.
The phase 2 trial randomly assigned 106 women with stage II to III estrogen receptor–positive, HER2-negative luminal breast cancer who were not candidates for BCS to receive chemotherapy or letrozole plus palbociclib. The primary endpoint was residual cancer burden (RCB) rate and secondary endpoints included objective response rate, BCS rates, and safety.
RCB rates were similar between groups, with 0, I, II, and III rates of 3.8%, 3.8%, 52%, and 40.4%, respectively, in the letrozole plus palbociclib arm compared with 5.9%, 9.8%, 37.3%, and 47.1%, respectively, in the chemotherapy arm.
The objective response rates were also similar at 74.5% and 76% in the letrozole plus palbociclib and chemotherapy arms, respectively. The BCS rates were 69.2% among those who received letrozole and palbociclib compared with 68.6% among patients who received chemotherapy.
Serious adverse events occurred more frequently with chemotherapy (17 patients) compared with letrozole plus palbociclib (2 patients; P < .001).
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The investigators indicated that analyses of the data are ongoing. Though the clinical response and BCS rates were similar between arms, neoadjuvant treatment with letrozole plus palbociclib resulted in fewer serious adverse events.
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- Cottu P, D'Hondt V, Dureau S, et al. Letrozole and palbociclib versus 3rd generation chemotherapy as neoadjuvant treatment of minal breast cancer. Results of the UNICANCER-eoPAL study. Presented at: European Society of Medical Oncology (ESMO) 2017 Congress; Madrid, Spain: September 8-12, 2017. Abstract LBA9.