Abstract 222P
Background
Patients with inflammatory breast cancer (IBC) have a poor prognosis owing to the aggressive biology of the disease and relatively inferior response to standard of care therapies. Cyclin dependent kinase 4/6 inhibitors (CDKI) are utilized in the metastatic setting for hormone receptor-positive HER2-negative/low (HR+ HER2-) breast cancer. The outcomes of these patients treated with CDKI combined with hormone directed therapy are presented.
Methods
Patients with HR+ HER2- IBC for which CDKI was administered in the metastatic setting were identified from the IBC registry at MD Anderson Cancer Center (N= 58). Medians (95% confidence intervals) of overall survival (OS), progression free survival (PFS), and time on treatment (ToT) from the time of CDKI initiation are reported by Kaplan-Meier methods. Differences are tested by log-rank test.
Results
All patients (42 stage III, 16 de novo stage IV) received induction chemotherapy at diagnosis. Median OS, PFS, and ToT in the total cohort was 26 (16, 37), 7 (5, 10), and 7 (5, 10) months (mos), respectively. No differences were observed between pre and post-menopausal patients. OS, PFS, and ToT in initial diagnosis of Stage III (N=42) vs IV (N=16) patients was 19 (15, 34) vs 34 (21, NR), 7 (5, 14) vs 9 (6, NR), and 6 (5, 10) vs 9 (4, NR) mos, respectively (ns). Patients treated with abemaciclib (N=11), Palbociclib (N=36), and ribociclib (N=9) show PFS of 7 (3, NR), 6 (4, 10), 9 (7, NR) mos; and ToT of 6 (3, NR), 6 (4, 9), 9 (7, NR) mos. OS, PFS, and ToT in patients receiving CDKI in the fistr-line vs second-line metastatic setting were 27 (19, 44) vs 17 (12, 39), 7 (5, 15) vs 6 (3, NR), and 7 (5, 15) vs 6 (3, 20) mos, respectively (ns). Brain metastases were observed in 12/42 stage III patients.
Conclusions
Patients with metastatic HR+ HER2- IBC demonstrate a poor response to CDKI based therapy. Patients receiving CDKI in the first vs second-line setting demonstrated a relatively superior outcome. Overall, however, outcomes are significantly inferior to historical data compared to non-IBC. Small sample size precludes definitive conclusions and data should be interpreted cautiously.
Legal entity responsible for the study
A. Nasrazadani.
Funding
Has not received any funding.
Disclosure
A. Nasrazadani: Other, Personal, Invited Speaker: AstraZeneca; Other, Personal, Advisory Role: Novartis. All other authors have declared no conflicts of interest.