483P - Prognostic value of androgen receptor expression in patients with advanced triple-negative metastatic breast cancer treated with sacituzumab govitecan: A French multicentre retrospective study

Background

Androgen receptor (AR) is expressed in around 30% of triple-negative breast cancer (TNBC) tumors, and presents with different clinical evolution and resistance to standard chemotherapy. Sacituzumab govitecan (SG) is an antibody-drug conjugate recently approved in TNBC advanced tumors.

Methods

We conducted a retrospective study in 8 French University Hospitals and cancer centers. All patients with TNBC MBC treated with SG were included. The primary endpoint was progression-free survival (PFS) as per AR expression (cut-off 10%). Secondary endpoints included overall survival (OS). Univariable and multivariable analyses were performed.

Results

A total of 127 patients were included, of which 88 (69%) were AR-. The median age was 51yo (range 25 - 77), with younger patients in AR- (47yo) vs. AR+ (55.5yo; p=0.02). AR- tumors were mostly ductal subtype (95.5% vs. 82.1%; p=0.005) and higher grade III (79.8% vs. 58.3%; p=0.021). No differences were observed between AR- and AR+ in the median number of prior treatments at SG start: 2 (0 - 11) and the median number of SG cycles: 6 (1 - 28) with 27 patients (21.3%) still on SG at the time of analyses. With a median FU of 10.4m [95%CI 8.3-11.2], median PFS was 4.1m [3.7-4.7] with no differences based on AR expression (4.1m vs. 4.3 m, AR- vs. AR+, respectively; HR 0.83 [95%CI: 0.53-1.32], p=0.432). In univariable analysis, age at SG treatment (HR 0.98 [0.97-1.00]; p=0.028), adjuvant capecitabine (HR 1.65 [1.06-2.56]; p=0.025), and metastasis-free interval (MFI) (HR 2.39 [1.38-4.14] and 1.09 [0.63-1.91] for 6-24m and > 24m respectively vs. < 6m) were associated with PFS. Short MFI remained significant for worse prognosis in a multivariable analysis (HR (6-24m vs. <6m) 2.0 [1.04-3.88]; p=0.039). The mOS was 9.7m [7.1-12.2] with 67 (52.8%) patients still alive. AR was not associated with OS in the univariable (HR 0.66 [0.37-1.19]; p=0.165] or multivariable analyses (HR=0.69 [0.34-1.38]; p=0.290].

Conclusions

Despite AR+ tumors being described as lesser chemo-sensitive, in this large retrospective cohort, AR expression was not associated with benefit in terms of PFS and OS from SG in patients with advanced TNBC.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Institut Bergonie.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.