Efficacy and Safety Analysis of Nab-Paclitaxel Treatment in Elderly Patients with HER-2 Negative Metastatic Breast...

Background: Older women represent a significant and increasing population of patients with breast cancer, accounting for over 40% of new cases of breast cancer. However, this growing subgroup of patients is still underrepresented in clinical trials, and treatment is usually selected based on limited data from retrospective subgroup analyses. However, the ESMO guidelines for metastatic breast cancer (mBC) suggest that the management decision should not be based on age alone. Nab-paclitaxel (nab-P) was associated with improved efficacy and a better safety profile than solvent-based taxanes without steroid or antihistamine premedication, making this treatment appealing to elderly patients. Patients and methods: This is an observational, retrospective, multicenter study, evaluating the safety and activity of nab-paclitaxel (nab-P) in elderly patients (≥65 years old) with HER2-negative mBC from 11 Sicilian oncology centers. The primary endpoint of the study was the safety nab-P in elderly mBC patients; secondary endpoints included the overall response rate (ORR), progression-free survival (PFS), and overall survival (OS). Results: We included 70 patients, and all were evaluable for safety and efficacy. All patients had previously been pretreated with taxane-based chemotherapy in a (neo)-adjuvant or metastatic setting. One third of the patients received nab-P as a fourth line therapy. Most of the patients were treated with nab-P at doses of 260 mg/m² 3-weekly (87.1%), and 12.9% received a nab-P dose of 125 mg/m² weekly. Patients' characteristics included a median age of 67 years (range 65-83 years), a median ECOG PS of 1 (range 0-2), and the following intrinsic molecular subtypes: Luminal A (18.8%), Luminal B HER-2 negative (62.5%), and triple negative (18.8%). Nab-P was administered for a median of six cycles (range 1-21), with 35.5% of patients experiencing a dose reduction, and 11.5% treatment discontinuation due to toxicity. Adverse events were mainly G2-G3 and occurred mostly in patients treated with 3-weekly nab-P (85.7%). The ORR was 31.3% (CR in 6.3% and PR in 25% of pts) and the DCR was 70.4%. Median PFS was 6 months (95% CI, 2-38), and median OS was 40.5 months (95% CI, 7-255). Conclusions: Our real-life study showed that nab-P is an effective, well-tolerated regimen in elderly mBC patients, including taxane-pretreated patients, and can be safely administered in elderly mBC patients.