246P - Axillary management and outcomes after neoadjuvant endocrine therapy in the randomized PELOPS trial

Background

There is limited data to guide axillary surgery after neoadjuvant endocrine therapy (NET). Here we report axillary status, surgery and outcomes among patients (pts) enrolled to the Palbociclib and Endocrine therapy for LObular breast cancer Preoperative Study (PELOPS).

Methods

Women with cT >1.5cm, N0-3, hormone receptor-positive, HER2-negative breast cancer were randomized 2:1 to NET + Palbociclib (Palbo) vs NET for 24 weeks. Node-positive (cN+) disease was biopsy-proven. Axillary surgery (sentinel lymph node biopsy (SLNB) +/- axillary dissection (ALND)) and nodal evaluation (H&E +/- IHC) were not protocolized. Pre-specified exploratory endpoints were ypN+ rates, local-regional recurrence-free interval (LRFI), and breast cancer-specific survival (BCSS), compared by univariate Cox proportional hazards model.

Results

188 pts were analyzed (128 treated with NET + Palbo, 60 NET). Median age was 56.5 yrs (range 32.0-83.0); 82 (43.6%) had lobular cancer, 99 (52.7%) were cN0, 84 (44.7%) cN+, 5 (2.6%) unknown cN. Of pts with known cN/ypN status, rates of ypN+ disease were 37/92 (40.2%) and 68/77 (88.3%) among cN0 and cN+ patients, respectively (14 unknown ypN). After NET + Palbo, 24/63 (38.1%) cN0 pts were ypN+ and 6/55 (10.9%) cN+ pts had a nodal pCR; after NET alone, 13/29 (44.8%) cN0 pts were ypN+ and 3/22 (13.6%) cN+ pts had a nodal pCR (Table). At a median follow-up of 4.65 yrs (IQR 3.66, 5.56), there was no difference in LRFI by treatment arm. Overall, among 108 ypN+ pts, 26 (24.1%) underwent SLNB, 82 (75.9%) ALND, 99 (91.7%) radiation, and there was no difference in LRFI or BCSS based on the performance of SLNB or ALND (unadjusted HR 1.55 [0.30, 7.92], p=0.59 and 1.10 [0.12, 9.96], p=0.934, respectively). Table: 246P

Conclusions

The addition of Palbo to NET did not impact pathologic nodal outcomes: nodal pCR rates were 10.9% after NET + Palbo and 13.6% after NET. Among those with ypN+ disease, neither LRFI nor BCSS appears to be impacted by the performance of ALND.

Clinical trial identification

NCT02764541 Dana Farber DFCI IRB: 16-052.

Editorial acknowledgement

Legal entity responsible for the study

Anna Weiss.

Funding

This work was funded by a Breast Cancer Alliance Exceptional Project Award. The PELOPS trial was supported by Pfizer.

Disclosure

A.C. Weiss: Non-Financial Interests, Institutional, Advisory Board: Myriad, Merck, Abbvie. M.A.A. Fenton: Non-Financial Interests, Institutional, Other, Spouse Consultant: Astellas. L.C. Kennedy: Non-Financial Interests, Institutional, Advisory Board: Daiichi Sankyo; Financial Interests, Institutional, Research Funding: Roche-Genentech, Puma Biotechnology. E. Mittendorf: Financial Interests, Personal, Advisory Board: Merck, BioNTech, AstraZeneca; Financial Interests, Personal, Invited Speaker: MSD; Financial Interests, Institutional, Research Grant, I have a grant from SU2C funded by Roche/Genentech that supports the conduct of a clinical trial: Roche/Genentech; Financial Interests, Institutional, Coordinating PI, Gillead provides clinical trial support to my institution for a study that I am the PI on: Gillead; Financial Interests, Personal, Steering Committee Member: Roche/Genentech, BMS; Non-Financial Interests, Member of Board of Directors: American Society of Clinical Oncology; Non-Financial Interests, Advisory Role, I serve in an advisory role as a Komen Scholar: Komen for the Cure. O. Metzger: Financial Interests, Personal, Funding, Grant funding: Pfizer; Financial Interests, Personal, Other, Personal fees: Merck & Co, Oncoclicnicas. T.A. King: Financial Interests, Personal, Advisory Board, Compensated Services and Speakers Honoraria: Exact Sciences; Financial Interests, Personal, Leadership Role, Compensated service as faculty: PrecisCa Cancer Information Service. All other authors have declared no conflicts of interest.