Continuous Chemotherapy Improves TTF But Not OS in ER+/HER2- Advanced Breast Cancer

Vinorelbine plus cyclophosphamide and capecitabine (VEX) led to a significant improvement in time to treatment failure (TTF) compared with paclitaxel alone in patients with estrogen receptor (ER)–positive, HER2-negative locally advanced or metastatic breast cancer, according to findings from the phase 2 METEORA-II trial (NCT02954055) that were presented at the 2022 ESMO Congress.

The median TTF was 8.3 months with VEX (n = 71) vs 5.7 months with paclitaxel (n = 69; HR, 0.61; 95% CI, 0.42-0.88; P = .008). The 12-month TTF rates in the VEX and paclitaxel arms were 34.3% and 8.6%, respectively.

In the population of patients who had received prior endocrine therapy in combination with a CDK4/6 inhibitor, the median TTF was 8.4 months with VEX vs 5.6 months with paclitaxel (HR, 0.63; 95% CI, 0.37-1.06). The 12-month TTF rates with VEX and paclitaxel were 25.0% and 8.0%, respectively.

“METEORA-II successfully met its primary end point showing that the metronomic VEX significantly improved TTF compared with paclitaxel and should be considered as an option in patients requiring chemotherapy,” the study authors wrote in a presentation of the data.

A total of 140 patients were enrolled across 15 centers in Italy. Seventy patients received VEX and 63 received paclitaxel. A total of 70 patients in the VEX arm and 63 patients in the paclitaxel arm were analyzed for efficacy and safety.

To be eligible for enrollment, patients had to have histologically or cytologically confirmed ER-positive, HER2-negative locally advanced or metastatic breast cancer. The disease could have been measurable or non-measurable but needed to be radiologically evaluable per RECIST v1.1 criteria.

Additionally, patients needed to be at least 18 years of age, female, and have an ECOG performance status of 0 or 1. They could not have received more than 1 line of chemotherapy for advanced or metastatic breast cancer, nor could they have received more than 2 lines of prior endocrine therapy for locally advanced or metastatic disease.

Participants were randomly assigned 1:1 to 90 mg/m² of intravenous paclitaxel on days 1, 8, and 15 every 4 weeks, or metronomic VEX consisting of 40 mg of oral vinorelbine on days 1, 3, and 5 of every week; 50 mg of continuous oral cyclophosphamide daily; and 500 mg of continuous oral capecitabine 3 times a day until disease progression or lack of tolerability.

The primary end point of the trial was TTF. Secondary end points were investigator-assessed PFS, safety and tolerability, disease control, and OS.

Baseline characteristics illustrated that 46.7% of patients had received prior endocrine therapy in combination with a CDK4/6 inhibitor.

Additional results indicated that the median progression-free survival (PFS) was 11.1 months with VEX vs 6.9 months with paclitaxel (HR, 0.67; 95% CI, 0.46-0.96). The 12-month PFS rates with VEX and paclitaxel were 43.5% and 21.9%, respectively.

The median overall survival (OS) was 29.5 months with VEX vs 33.7 months with paclitaxel (HR, 0.98; 95% CI, 0.59-1.63). The 12-month OS rates with VEX and paclitaxel were 79.9% and 79.2%, respectively.

Regarding adverse effects (AEs) prior to the TTF event, 95.5% of patients (n = 127/133; 95% CI, 90.4%-98.3%) experienced at least 1 targeted AE. At least 1 AE was grade 3 or higher in 36.1% of patients (n = 48/133; 95% CI, 27.9%-44.9%).

More grade 3 or higher targeted AEs occurred in the VEX arm compared with the paclitaxel arm, at 42.9% (95% CI, 31.1%-55.3%) vs 28.6% (95% CI, 17.9%-41.3%), respectively.

Reference

Munzone E, Regan MM, Cinieri S, et al. A randomized phase II trial of metronomic oral vinorelbine plus cyclophosphamide and capecitabine (VEX) vs weekly paclitaxel as firstor second-line treatment in patients with ER+/HER2- metastatic breast cancer (MBC): the METEORA-II trial (IBCSG 54-16). Ann Oncol. 2022;33(suppl 7):S636-S637. doi:10.1016/j.annonc.2022.07.255