Overall Survival Benefit with the Addition of Capecitabine to Adjuvant Chemotherapy

SUMMARY: Breast cancer is the most common cancer among women in the US and about 1 in 8 women (12%) will develop invasive breast cancer during their lifetime. Approximately 290,560 new cases of breast cancer will be diagnosed in 2022 and about 43,780 individuals will die of the disease, largely due to metastatic recurrence.

Patients with early stage breast cancer often receive adjuvant chemotherapy to improve Overall Survival (OS), and this is even more so true for HER positive and triple negative (ER, PR and HER negative) breast cancer patients, who are at an increased risk to develop recurrent disease. Meta-analyses conducted by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) has shown a 20-25% relative risk reduction in breast cancer mortality with first-generation adjuvant chemotherapy regimens such as CMF (Cyclophosphamide/Methotrexate/Fluorouracil) and additional survival benefit with the Anthracyclines and Taxane based regimens. This benefit is dependent on the type of chemotherapy administered and chemotherapy dose intensity.

XELODA® (Capecitabine) is an oral prodrug of fluorouracil which is presently approved for the treatment of advanced breast cancer, but NOT for neoadjuvant or adjuvant treatment of early breast cancer. Meta-analysis of randomized trials has found that addition of Capecitabine to standard adjuvant chemotherapy regimens prolongs Disease Free Survival (DFS), whereas replacing a standard agent with Capecitabine did not improve DFS. Preclinical models have suggested that chemotherapy agents such as taxanes, and Cyclophosphamide increase thymidine phosphorylase concentration in the cancer cell, potentially leading to improved conversion of Capecitabine to fluorouracil within the tumor, suggesting that concomitant administration of Capecitabine with these agents improves efficacy, compared with single-agent Capecitabine. The researchers in this publication addressed the question whether addition of Capecitabine to these regimens could lead to improved survival outcomes.

The Finland Capecitabine Trial (FinXX) is a randomized, open-label, multicenter, Phase III trial that evaluated the addition of Capecitabine to an adjuvant chemotherapy regimen containing a taxane and an anthracycline for the treatment of early breast cancer. In this study, 1,500 patients with axillary node-positive or high-risk node-negative early breast cancer were randomly assigned to 6 cycles of either the Capecitabine arm- TX-CEX (N=753) or to the control group-T-CEF (N=747). TX-CEF consisted of Docetaxel 60 mg/m2 IV day 1 and Capecitabine 900 mg/m2 PO BID on days 1-15 of a 21-day cycle for 3 cycles followed by CEX consisting of Cyclophosphamide 600 mg/m2 IV Day 1, Epirubicin 75 mg/m2 IV on Day 1 and Capecitabine 900 mg/m2 PO BID on days 1-15 of a 21 day cycle for 3 cycles. T-CEF consisted of Docetaxel 80 mg/m2 IV Day 1, every 3 weeks for 3 cycles followed by CEF consisting of Cyclophosphamide 600 mg/m2 IV, Epirubicin 75 mg/m2 IV and Fluorouracil 600 mg/m2 IV, all administered on Day 1, every 3 weeks for 3 cycles. Adjuvant endocrine therapy was initiated within 2 months after completion of chemotherapy if the tumor was ER or PR-positive. Radiotherapy was given after completion of chemotherapy according to each institution’s practice. Adjuvant Trastuzumab was approved while the trial accrual was ongoing and was allowed for women with HER2-positive cancer after May 2005, and adjuvant Trastuzumab was administered to 13% patients assigned to TX-CEF and 11% patients assigned to T-CEF. The median patient age was 52.5 yrs, 76% of patients had ER-positive tumors, 19% had HER2-positive cancer, 13% had Triple Negative Breast Cancer, more than 90% had T1 or T2 tumors, and 89% were node positive. The researchers then performed a protocol-scheduled analysis of Overall Survival on the basis of approximately 15-year follow up of the patients.

At a median follow up of 15.3 years, the Overall Survival was 77.6% in the TX-CEX group and 73.3% in the T-CEF group (HR=0.81; P=0.037). Exploratory subgroup analysis suggested that patients with ER-negative disease and those with Triple Negative Breast Cancer lived longer with the addition of Capecitabine (TX-CEX regimen), than those treated with T-CEF.

It was concluded that the addition of Capecitabine to a chemotherapy regimen significantly improved Overall Survival at median follow up of 15 years in a patient population with early breast cancer, suggesting that Capecitabine may be an important addition to adjuvant chemotherapy in patients with high risk disease.

Adjuvant Capecitabine for Early Breast Cancer: 15-Year Overall Survival Results from a Randomized Trial. Joensuu H, Kellokumpu-Lehtinen P-L , Huovinen R, et al. DOI: 10.1200/JCO.21.02054 Journal of Clinical Oncology. Published online January 12, 2022.