Phase II randomized trial of different nab-paclitaxel dose schedule in patients with HER-2 negative recurrent/metastatic breast cancer.

Abstract

e13050 Background: This study was to compare the efficacy and safety of different nab-paclitaxel dose schedule in patients with HER-2 negative recurrent/metastatic breast cancer in order to find a more suitable treatment option for Chinese patients. Methods: This is a single-center, open-label, randomized, phase II trial. Eligible female patients with HER-2 negative recurrent/metastatic breast cancer and up to 2 lines of prior chemotherapy regardless of any endocrine therapy were randomly assigned (1:1) to either nab-paclitaxel (125mg/m2 IV days 1, 8, every 21 days, 3-week group) or nab-paclitaxel (125mg/m2 IV days 1, 8, 15, every 28 days, 4-week group) until progressive disease or completion of 6-8 cycles of treatment. After completing 6-8 cycles, if the efficacy evaluation is CR, PR or SD, the investigator can decide whether to carry out maintenance therapy. The primary endpoint is PFS. Secondary endpoints are ORR, OS and safety. Results: Between March 2019 and July 2021, 104 patients with HER-2 negative breast cancer were randomly assigned to treatment (3-week group, n = 51; 4-week group, n = 53). Median follow-up was 16.4 and 15.8 months. In the 3-week and 4-week groups, respectively, 39 (76.5%) and 42 (79.2%) patients had HR positive disease and 37 (72.5%) and 43 (81.1%) patients had visceral metastasis. In two groups, respectively, 30 (58.8%) and 20 (37.7%) patients didn’t receive prior endocrine therapy. 20 (39.2%) and 32 (60.4%) patients had received 1 to 3 lines of prior endocrine therapy. 30 (58.8%) patients of 3-week group and 30 (56.6%) patients of 4-week group were enrolled at first-line chemotherapy, and 13 (25.5%) of 3-week group patients and 16 (30.2%) patients of 4-week group were enrolled at second-line chemotherapy, as third-line chemotherapy there were only 8 (15.7%) in 3-week group and 7 (13.2%) in 4-week group. Among all patients, 33 (64.7%) in the 3-week group and 16 (30.2%) in the 4-week group had received 6-8 cycles according to the regimen of study, and 32 (97.0%) of 3-week group and 15 (93.8%) of 4-week group patients who finished the regimen choose to receive maintenance treatment (endocrine or chemotherapy).In two groups, respectively, median PFS was 9.6 months and 7.5 months (HR 0.905; 95%CI 0.569-1.440) and ORR were 50.0% (23/46) and 46.9% (23/49) in the evaluable population. Median OS was 22.5 months in the 3-week group and has not yet been reached for the 4-week group. According to NCI-CTCAE V5.0, 3-week group vs 4-week group respectively, the grade 3-4 adverse events (≥2 patients) were neutropenia (13.7% vs 34.0%), leukopenia (7.8% vs 17.0%) and peripheral neurotoxicity (0 vs 3.8%). Conclusions: Preliminary results suggest that compared with the 4-week regimen, the 3-week regimen of nab-paclitaxel seems to be more suitable and adaptable for Chinese patients with advanced breast cancer. This study is still in follow-up and updated data will be presented. Clinical trial information: NCT04192331.