Factors affecting prognosis in patients treated with bevacizumab plus paclitaxel as first-line chemotherapy for HER2-negative metastatic breast cancer: an international pooled analysis of individual patient data from four prospective observational studies

Background: Bevacizumab (BV) plus paclitaxel (PTX) is a treatment option in patients with HER2-negative metastatic breast cancer (mBC). We conducted an international pooled analysis with individual patient data to evaluate the effectiveness of BV + PTX as a first-line treatment for HER2-negative mBC patients under routine practice.

Methods: A total of 2,474 mBC patients treated with BV + PTX from four prospective observational studies were analyzed. The primary endpoint was overall survival (OS). The other endpoints including identifying independent prognostic factors and validation of the modified Prognostic Factor Index (PFI) developed in the ATHENA trial.

Results: Median follow-up time was 10.9 months (M). Median OS were 21.4 M (95% confidential interval 19.8-22.7 M). The seven independent prognostic factors (tumor subtype, age, ECOG performance status (PS), disease-free interval (DFI), liver metastases, number of metastatic organs, and prior anthracycline and/or taxane treatment) for OS found in this analysis included the five risk factors (RFs [DFI < 24 months, ECOG PS 2, liver metastases and/or > 3 metastasis organ sites, TNBC, prior anthracycline and/or taxane therapy]). High- (> 3 RFs [median OS 12.6 M]) and intermediate-risk groups (2 RFs [median OS 18.0 M]) had a significantly worse prognosis than the low-risk group (< 1 RF [median OS 27.4 M]), (p < 0.0001).

Conclusions: This international pooled analysis showed the effectiveness of first-line BV + PTX for HER2-negative mBC patients identifying seven independent prognostic factors as real-world evidence. The usefulness of the modified PFI developed in the ATHENA trial in predicting OS among patients receiving BV + PTX was also verified.