Taxane-based treatment options for patients with HER2-positive advanced breast cancer: results of an observational study

Background: Treatment of HER2-positive (HER2+) breast cancer is based on the use of drugs targeting HER2 (anti-HER2 treatment). Trastuzumab is the current standard treatment (trt) for patients (pts) with HER2+ advanced breast cancer (BC) not previously treated with trastuzumab. This study explores taxane-based trt options for pts with HER2+ advanced BC in daily practice and assesses their effectiveness.

Methods: This was a prospective non-interventional study to determine factors associated with the choice of taxane-based trt in pts with advanced BC pre-treated with anthracyclines unless contra-indicated. Patient characteristics were analysed using descriptive statistics. Progression-free survival (PFS) was estimated by the Kaplan-Meier method.

Results: 465 pts prescribed first-line trt were eligible for analysis. Among them there were 104 HER2+ patients with median age of 53 years (in scope of this abstract). ECOG performance status (PS) was 0-1 in 88.5% and hormonal receptors status was positive (HR+) in 50.0% of pts. Median disease free interval (DFI) was 25.5 months (mo). 91.3% had metastatic breast cancer (MBC) and 61.5% of pts had visceral metastases. No patients had received trastuzumab as adjuvant treatment. Trastuzumab in combination with taxane was prescribed in only 61 pts (59%): 47 pts (45%) without other cytotoxic and 14 pts (13%) in combination with other cytotoxic agents. 11 pts (11%) were assigned to trt with single-agent taxane. PFS results for different treatment options are presented in the table.

Trt options	No. of	PFS, mo
	pts	Median	95% CI
All HER2-positive pts	104
Trastuzumab trt	61	19.7	(9.3, unest.)
Non-trastuzumab trt	41	7.9	(5.0 to 19.2)
- Taxane combinationCT	30	18.8	(5.0 to 22)
- Taxane monotherapy	11	6.1	(3.8 to 13.3)
CT = chemotherapy, PFS =
progression-free survival

Conclusions: Patient with HER2+ advanced breast cancer may not receive anti-HER2 trt in practice. These results suggest that taxane-combination chemotherapy might be a trt option for this population. Further studies are warranted to understand the potential hurdles for use of anti-HER2 trt and to define the best trt strategy for this population. Funding: Study B9E-VI-B007 was sponsored by Eli Lilly.

Disclosure: A. Kral, S. Weitckus and V. Soldatenkova: Employee of Eli Lilly; K. Benhadji: Lilly employment and stock ownership. All other authors have declared no conflicts of interest.