Patterns of treatment and outcome of fulvestrant 500mg in postmenopausal women with hormone-positive (HR+)/Her2-negative (HER2-) metastatic breast cancer (MBC): a real life multicenter Italian experience

Abstract

Background: Fulvestrant 500 mg (F500) is a well-established therapeutic option for HR + /HER2- MBC postmenopausal patients ( pts) who had previously progressed on hormonal therapy. Available data on F500 use in routine clinical practice are lacking. This retrospective multicenter observational study was conducted to describe the patterns of treatment and outcome of F500 in the real life setting, Methods: Data of postmenopausal HR + /HER2- MBC pts who received F500 from January 2011 to December 2014 were collected from institutional databases of 4 Italian Centers. The primary study aim was to analyze progression-free survival (PFS) and Clinical Benefit Rate (CBR: complete response [CR] + partial response [PR] + stable disease [SD] > 24 weeks); secondary endpoints included overall survival (OS) and safety profile. Results: 490 pts were included in the study, 480 were evaluable. F500/month was given as 1st up to 7th treatment line: 1st line in 24% of pts, 2nd line in 35%, >3rd in 41%. 306 pts received the drug upon progression of disease (PD) on prior endocrine treatment, 92 and 68 as maintenance therapy following 1st or 2nd line chemotherapy, respectively; 21% of pts had De novo metastatic disease. Median age: 66 years (range 56-81); visceral metastases: 32%; ECOG PS = 1: 62%. Median of cycles administered: 14 (range 6-28). At a median follow-up of 18 months (range 6-38) median PFS was 11.6 months (range 8.1-16.2: 12.5 in 1st line, 11.4 in 2nd line, 9.2 in >3 lines), CBR was 68.6% (8.8% CR, 21.6 PR, 38,2 SD> 24 weeks). No differences in CBR (67.8% vs 69.1%) and PFS (11.5 vs 11.6 months) were observed between pts receiving F500 as maintenance therapy and those treated at PD on prior therapy. Median OS was 44.2 months (range 35-NR). More frequent toxicities did not exceed grade 1 NCI-CTC: local injection site pain (11.2%), joint disorders (6.2%), hot flushes (4.9%). Conclusions: Our real word experience confirm that F500 can safely be offered to most women with HR + /HER2- MBC, with interesting expectations of PFS and CBR and good safety profile, producing similar outcomes as both upon PD treatment and maintenance therapy.