Efficacy of oral tegafur-uracil (UFT) as adjuvant therapy as compared with classical cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) in early breast cancer: a pooled analysis of two randomized controlled trials (N·SAS-BC 01 trial and CUBC trial)

A risk-based subgroup analysis of the effect of adjuvant S-1 in estrogen receptor-positive, HER2-negative early breast cancer

PURPOSE

The Phase III POTENT trial demonstrated the efficacy of adding S-1 to adjuvant endocrine therapy for estrogen receptor-positive, HER2-negative early breast cancer. We investigated the efficacy of S-1 across different recurrence risk subgroups.

METHODS

This was a post-hoc exploratory analysis of the POTENT trial. Patients in the endocrine-therapy-only arm were divided into three groups based on composite risk values calculated from multiple prognostic factors. The effects of S-1 were estimated using the Cox model in each risk group. The treatment effects of S-1 in patients meeting the eligibility criteria of the monarchE trial were also estimated.

RESULTS

A total of 1,897 patients were divided into three groups: group 1 (≤ lower quartile of the composite values) (N = 677), group 2 (interquartile range) (N = 767), and group 3 (> upper quartile) (N = 453). The addition of S-1 to endocrine therapy resulted in 49% (HR: 0.51, 95% CI: 0.33-0.78) and 29% (HR: 0.71, 95% CI 0.49-1.02) reductions in invasive disease-free survival (iDFS) events in groups 2 and 3, respectively. We could not identify any benefit from the addition of S-1 in group 1. The addition of S-1 showed an improvement in iDFS in patients with one to three positive nodes meeting the monarchE cohort 1 criteria (N = 290) (HR: 0.47, 95% CI: 0.29-0.74).

CONCLUSIONS

The benefit of adding adjuvant S-1 was particularly marked in group 2. Further investigations are warranted to explore the optimal usage of adjuvant S-1.

Adjuvant S-1 plus endocrine therapy for oestrogen receptor-positive, HER2-negative, primary breast cancer: a multicentre, open-label, randomised, controlled, phase 3 trial

BACKGROUND

Oral fluoropyrimidines, such as S-1, have been shown to have a role in controlling disease progression in metastatic breast cancer. We examined adjuvant treatment with S-1 in patients with oestrogen receptor (ER)-positive and HER2-negative primary breast cancer.

METHODS

We did a multicentre, open-label, randomised, controlled, phase 3 trial in 139 sites (137 hospitals and two clinics). Eligible patients were women aged 20-75 years with histologically diagnosed stage I to IIIB invasive breast cancer (intermediate to high risk of recurrence). Patients were temporarily registered at participating institutions and biopsy or surgical samples were collected and sent for central pathological assessment. Patients received 5 years of standard adjuvant endocrine therapy (selective oestrogen receptor modulators with or without ovarian suppression and aromatase inhibitors) with or without 1 year of S-1. Oral S-1 80-120 mg/day was administered twice a day for 14 days with 7 days off. Randomisation (1:1) using the minimisation method was done with six stratification factors (age, axillary lymph node metastasis at surgery or sentinel lymph node biopsy, preoperative or postoperative (neoadjuvant or adjuvant) chemotherapy, preoperative endocrine therapy, proportion of ER-positive cells, and study site). The primary endpoint was invasive disease-free survival, in the full analysis set (all randomly assigned patients, excluding those with significant protocol deviations). The safety analysis set consisted of all patients who received at least one dose of study treatment. Here, we report the results from the interim analysis at the data cutoff date Jan 31, 2019. This trial is registered with Japan Registry of Clinical Trials, jRCTs051180057, and the University hospital Medical Information Network, UMIN000003969.

FINDINGS

Between Feb 1, 2012, and Feb 1, 2016, 1930 patients were enrolled in the full analysis set, 957 (50%) received endocrine therapy plus S-1 and 973 (50%) received endocrine therapy alone. Median follow-up was 52·2 months (IQR 42·1-58·9). 155 (16%) patients in the endocrine therapy alone group and in 101 (11%) patients in the endocrine therapy plus S-1 group had invasive disease-free survival events (hazard ratio 0·63, 95% CI 0·49-0·81, p=0·0003). As the primary endpoint was met at interim analysis, the trial was terminated early. The most common grade 3 or worse adverse events were decreased neutrophil count (72 [8%] of 954 patients in the endocrine therapy plus S-1 group vs seven [1%] of 970 patients in the endocrine therapy alone group), diarrhoea (18 [2%] vs none), decreased white blood cells (15 [2%] vs two [<1%]), and fatigue (six [<1%] vs none). Serious adverse events were reported in nine (1%) of 970 patients in the endocrine therapy alone group and 25 (3%) of 954 patients in the endocrine therapy plus S-1 group. There was one (<1%) possible treatment-related death in the endocrine therapy plus S-1 group due to suspected pulmonary artery thrombosis.

INTERPRETATION

These data suggest that this combination of S-1 with endocrine therapy could be a potential treatment option for this intermediate and high-risk group of patients with ER-positive, HER2-negative primary breast cancer.

FUNDING

Public Health Research Foundation (Japan), Taiho Pharmaceutical.

Relationships between pathological factors and long-term outcomes in patients enrolled in two prospective randomized controlled trials comparing the efficacy of oral tegafur-uracil with CMF (N·SAS-BC 01 trial and CUBC trial)

PURPOSE

To evaluate the efficacies of cyclophosphamide, methotrexate, and fluorouracil (CMF) and tegafur-uracil (UFT) as adjuvant therapy in patients with resected stage I-IIIA breast cancer by immunohistochemistry (IHC)-based subtype and to determine the relationships between clinicopathological factors and long-term outcomes.

METHODS

A pooled analysis of the randomized controlled N·SAS-BC 01 and CUBC studies was conducted. Expression of hormone receptors (HRs; estrogen and progesterone receptors), human epidermal growth factor receptor 2 (HER2), and Ki67were assessed by IHC. Tumor-infiltrating lymphocytes (TILs) and nuclear/histological grades were determined by hematoxylin and eosin staining. Relapse-free survival (RFS) and overall survival (OS) were estimated by Kaplan-Meier analysis and hazard ratios were determined by Cox model adjusted for baseline tumor size and nodal status.

RESULTS

A total of 689 patients (342 CMF and 347 UFT) were included in the analyses with a median follow-up of 11.1 years. There was no significant difference in RFS or OS between the two cohorts (RFS: 0.96 [95% confidence interval: 0.71-1.30], log-rank test p = 0.80; OS: 0.93 [0.64-1.35], p = 0.70). There was no difference in RFS or OS between the two cohorts for HR+/HER2- and HR+/HER2+ subtypes. RFS was significantly longer in patients treated with UFT compared with CMF in patients with HR-/HER2+ subtype (0.30 [0.10-0.88], p = 0.03). A high TILs level was associated with a better OS compared with low TILs level (p = 0.02).

CONCLUSIONS

This long-term follow-up study showed that RFS and OS were similar in patients with luminal-type breast cancer treated with CMF and UFT.

Estrogen Down-regulator Fulvestrant Potentiates Antitumor Activity of Fluoropyrimidine in Estrogen-responsive MCF-7 Human Breast Cancer Cells

BACKGROUND

Endocrine therapy is clinically administered in hormone-responsive breast cancer. Combinations of fluoropyrimidine S-1 and an aromatase inhibitor or anti-estrogen are considered beneficial in Japan. Herein we assessed new combinations of S-1 and fulvestrant.

PATIENTS AND METHODS

Cytotoxicity of fulvestrant and 5-fluorouracil (5-FU) was assessed in hormone-responsive (MCF-7) and non-responsive (MDA-MB-231) breast cancer cell cultures. Fulvestrant and S-1 were evaluated for antitumor activity in mice and their effects on estrogen receptor (ER)-α and progesterone receptor (PgR) levels in MCF-7 xenografts using immunohistochemical methods.

RESULTS

Fulvestrant inhibited growth of MCF-7, but not of MDA-MB-231 xenografts. Combinations of 5-FU and fulvestrant were superior to monotherapy in vitro. In vivo antitumor activity of S-1/fulvestrant combination therapy was significantly (p<0.05) enhanced compared to that of both monotherapies. Fulvestrant partially down-regulated expression of ERα and PgR, but in combination with S-1, it almost completely blocked their expression.

CONCLUSION

Chemo-endocrine combination therapy using S-1 and fulvestrant is beneficial in estrogen-responsive breast cancer.

Association between SLCO1B1 rs4149056 and tegafur-uracil-induced hepatic dysfunction in breast cancer

Aim: The aim of this study was to identify pharmacogenomic biomarkers to predict tegafur-uracil (UFT)-induced liver dysfunction. Patients & methods: A total of 68 patients, who were administered UFT, were evaluated using a two-step pharmacogenomics analysis. Results: The first screening revealed the association between five SNPs and UFT-induced hepatic dysfunction. In the second step, SLCO1B1 (rs4149056) was found to be the only SNP associated with UFT treatment-related elevation of aspartate aminotransferase (odds ratio: C/C vs T/T = 7.8, C/T vs T/T = 5.7; p = 0.037) and alanine transaminase (odds ratio: C/C vs T/T = 12.2, C/T vs T/T = 4.1; p = 0.034) levels. Conclusion: The SLCO1B1 polymorphisms are possible predictors of UFT treatment-related hepatic dysfunction.

Randomized phase II study of anastrozole plus tegafur-uracil as neoadjuvant therapy for ER-positive breast cancer in postmenopausal Japanese women (Neo-ACET BC)

Purpose

This phase II study evaluated the efficacy and safety of anastrozole concurrent with tegafur/uracil (UFT) as neoadjuvant therapy for ER-positive postmenopausal breast cancer.

Methods

Postmenopausal Japanese women with ER-positive, HER2-negative, T2,N0-1,M0 breast cancer seen at tertiary hospitals were eligible for this open-label, randomized, multicenter study. Patients were randomized 1:1 by minimization to orally receive either anastrozole (1 mg once daily) plus UFT (tegafur/uracil combination in 1:4 molar ratio; 270 mg/m²/day in two divided doses) or anastrozole (as above) alone for 24 weeks. Tumor response was assessed by investigator and central review as per RECIST v1.1. The primary endpoint was the proportion of patients with best overall response of CR or PR [clinical response rate (RR)] determined by central radiologic review.

Results

The study was prematurely terminated due to Grade ≥ 3 liver dysfunction reported in 3 patients receiving anastrozole/UFT. Of 57 patients randomized before termination (29 anastrozole/UFT, 28 anastrozole), all were analyzed for safety and 56 (28 each group) for tumor response. Compared with anastrozole alone, anastrozole/UFT did not achieve significantly higher RR [39.3% (90% CI 23.8–56.5%) vs 14.3% (90% CI 5.0–29.8%); p = 0.0683, Fisher’s exact test], but produced significantly greater tumor shrinkage (mean tumor reduction rate 31.0 vs. 14.2%; p = 0.0181, unpaired t-test). Grade ≥ 3 adverse events were more common with anastrozole/UFT than with anastrozole (17.2 vs. 0%).

Conclusion

Although the study was terminated owing to the altered liver function, it showed that there was a trend to greater shrinkage of tumor in the combination group for ER-positive, HER2-negative postmenopausal breast cancer.

Metronomics in the neoadjuvant and adjuvant treatment of breast cancer

The concept of metronomic chemotherapy (MC) has evolved from a descriptive preclinical phenomenon encompassing inhibition of angiogenesis to a clinically validated treatment concept involving multiple potential mechanisms of action. Clinicians are progressively more incline to consider MC as a component of mainstream medical oncology practice in advanced breast cancer. However, more recently MC has been tested even in the adjuvant/neoadjuvant setting, taking the opportunity to obtain tumor specimens and blood samples, in order to identify tumor-specific or patient-specific biomarkers for personalizing treatments. In addition, the antiangiogenic and pro-immune nature of metronomic chemotherapy made triple negative breast cancer (TNBC) a good candidate for exploring low-dose maintenance treatment in the adjuvant setting or in combination with immunomodulatory drugs. The potential development of MC in breast cancer pass through the research to identify biomarkers and individual tumor characteristics that can better address the use of this treatment strategy in the future. Finally, the subjective attitude of patients represents one of the major factors that influence the choice and acceptance of a therapeutic program. Personal preference and considerations about quality of life should guide the treatment choice eventually prioritizing the use of MC. Nevertheless, more robust data from randomized phase III trials are needed in the future, in order to make clinicians more confident in using metronomic strategies.

Antitumor and anticancer stem cell activities of eribulin mesylate and antiestrogens in breast cancer cells

BACKGROUND

Eribulin mesylate (eribulin), a non-taxane microtubule dynamic inhibitor, has been widely used in the treatment of patients with advanced or metastatic breast cancer. The combined antitumor and anticancer stem cell (CSC) activities of eribulin with endocrine therapeutic agents have not yet been examined in breast cancer cells. We herein investigated the combined effects of eribulin and antiestrogens.

METHODS

A panel of eight breast cancer cell lines, including five estrogen receptor (ER)-positive and three ER-negative cell lines, was used. These cells were treated with eribulin and/or the antiestrogen, 4-hydroxytamoxifen or fulvestrant. Their growth inhibitory activities and effects on cell cycle progression, apoptosis, and the CSC population were investigated. CSCs were detected using the CD44/CD24/EpCAM, Aldefluor, and mammosphere assays.

RESULTS

The 50% growth inhibitory concentrations of eribulin were 0.38-2.64 nM for the eight cell lines tested. Eribulin exhibited significant antitumor activity under estrogen-supplemented conditions in ER-positive breast cancer cells. The combined antitumor activity of eribulin with an antiestrogen was evaluated using the combination index. The combination index was 0.43-1.46 for ER-positive cell lines. The additive antitumor effect of eribulin with 4-OHT was only significant in MCF-7 cells. Eribulin induced the accumulation of G2/M and apoptosis, while antiestrogens induced the retardation of G1-S cell cycle and apoptosis, respectively. Estrogen markedly increased the proportion of CSCs, whereas antiestrogens inhibited increases in ER-positive cell lines. Moreover, eribulin decreased the proportion of CSCs in either ER-positive or ER-negative cell lines. The combined treatment of eribulin with an antiestrogen did not additively decrease the proportion of CSCs in ER-positive cell lines.

DISCUSSION

The results of the present study demonstrated that eribulin had potent antitumor effects on estrogen-stimulated ER-positive breast cancer cells and the combined treatment of eribulin with an antiestrogen resulted in a weakly additive antitumor effect. We herein suggested for the first time that eribulin exhibited anti-CSC effects on either ER-positive or ER-negative breast cancer cells.

Orally administered S-1 suppresses circulating endothelial cell counts in metastatic breast cancer patients

BACKGROUND

S-1 is an oral cytotoxic preparation that contains tegafur. Gamma-butyrolactone (GBL) is a metabolite of tegafur that is known to suppress vascular endothelial growth factor (VEGF)-mediated angiogenic activity. The aim of this study was to determine the change in circulating endothelial cell (CEC) counts, GBL levels, and angiogenesis-related factors during S-1 administration in metastatic breast cancer (MBC) patients.

METHODS

Patients with HER2-negative MBC were eligible. S-1 was administered orally twice daily in a 4 week on/2 week off cycle until disease progression or unacceptable toxicity occurred. Blood was collected on the following: days 1, 43, 85 (before each cycle of S-1 administration), days 15, 57 (1 h after S-1 administration), and day 29. The CellSearch(®) system was used to count the CECs. The gas chromatographic-mass spectrometric method was used to measure plasma GBL and 5-FU levels. Levels of VEGF were assayed by enzyme-linked immunosorbent assay.

RESULTS

A total of 18 patients were enrolled. The plasma GBL levels on days 15 and 57 were 41.3 ± 15.8 and 41.0 ± 11.2 ng/mL, respectively. The CEC levels decreased on day 15, and significantly low levels were maintained until day 85 (P = 0.002 vs day 1). The plasma VEGF levels significantly decreased on day 15 (P = 0.012 vs day 1) and had a tendency to decrease until day 57.

CONCLUSIONS

This exploratory study showed that GBL levels increased, VEGF levels decreased, and CEC levels were suppressed during S-1 administration. S-1 appears to have anti-angiogenic activity.

Metronomic chemotherapy for cancer treatment: a decade of clinical studies

PURPOSE

Over the past few years, more and more new selective molecules directed against specific cellular targets have become available for cancer therapy, leading to impressive improvements. In this evolving scenario, a new way of delivering older cytotoxic drugs has also been developing. Many studies demonstrated that several cytotoxic drugs have antiangiogenic properties if administered frequently and at lower doses compared with standard schedules containing maximal tolerated doses (MTD). Such a new strategy, named metronomic chemotherapy, focuses on a different target: the slowly proliferating tumour endothelial cells. About 10 years ago, metronomic chemotherapy was firstly enunciated and hereafter many clinical experiences were published related to almost any cancer disease. This review analyses available studies dealing with metronomic chemotherapy and its combination with several targeted agents in solid tumours.

METHODS

A computerized literature search of MEDLINE was performed using the following search terms: metronomic OR "continuous low dose" AND chemotherapy AND cancer OR solid tumours.

RESULTS

Satisfactory results have been achieved in diverse tumour types, such as breast and prostate cancer or paediatric sarcomas. Moreover, many studies have reported that metronomic chemotherapy determined minimal toxicity compared to MTD chemotherapy. Overall, published series on metronomic schedules are very heterogeneous often reporting on retrospective data, while only very few studies were randomized trials. These limitations still prevent to draw definitive conclusions in diverse tumour types.

CONCLUSIONS

Large well-designed studies are eagerly awaited for confirming the promises of metronomic schedules and their combinations with targeted molecules.

Evidence produced in Japan: tegafur-based preparations for postoperative chemotherapy in breast cancer

Oral fluoropyrimidine anticancer agents (oral 5-fluorouracil [5-FU]) able to be used as chemotherapy for breast cancer include tegafur–uracil (UFT), tegafur–gimeracil–oteracil potassium (S-1), doxifluridine, and capecitabine. Since the 1980s, UFT has been most widely used for postoperative chemotherapy in breast cancer. UFT is an oral preparation that was designed to achieve and maintain high concentrations of 5-FU in plasma by combining tegafur, a prodrug of 5-FU, with uracil. UFT is characterized by mild adverse events, allowing long-term treatment. The prolonged maintenance of high plasma 5-FU concentrations has been suggested to inhibit micrometastases after surgery. Recently, large clinical trials conducted in Japan have shown that UFT-based postoperative chemotherapy is therapeutically useful in patients with node-negative (n0), high-risk breast cancer. We review the results of clinical trials of postoperative chemotherapy with UFT in Japan and discuss its roles and future prospects.

Preferences for oral versus intravenous adjuvant chemotherapy among early breast cancer patients

PURPOSE

The purpose of this study was to evaluate preferences for oral versus intravenous adjuvant chemotherapy among early breast cancer patients (UMIN-CTR number UMIN000004696).

PATIENTS AND METHODS

Eighty-two postmenopausal women with estrogen receptor-positive, human epidermal growth-factor receptor 2-negative breast cancer who had completed adjuvant chemotherapy were asked about their preferred route of administration of chemotherapy and the reason. Women also answered questions about their physical and psychological status and quality of life during chemotherapy.

RESULTS

Patients who had received oral chemotherapy preferred it more frequently than those who had received intravenous chemotherapy (100% versus 37%, respectively, chi-square =15.5; P<0.001). Patients who preferred the same route of administration of chemotherapy as they had previously received showed a significantly better psychological status during chemotherapy compared with those who preferred a different route.

CONCLUSION

Our study showed that preferences for oral and intravenous chemotherapy strongly depended on the actual prior administration of chemotherapy and patients' own experiences during chemotherapy.

Current status of therapy for breast cancer worldwide and in Japan

The results of clinical trials conducted in Europe and North America have been incorporated into treatment strategies for breast cancer in Japan. Despite the use of similar treatment regimens, why has mortality from breast cancer been increasing in Japan? Procedures for surgical treatment and sentinel lymph node biopsy in breast cancer do not differ between Japan and Western countries, but the strategies for radiotherapy differ slightly. Hormonal therapy is now selected on the basis of scientific evidence, and similar regimens are used in Japan and Western countries. As for postoperative adjuvant chemotherapy, an anthracycline plus cyclophosphamide and taxane-based regimens are standard treatments in Japan and Western countries. In 2009, however, the results of two large clinical studies designed to determine whether intravenous or oral treatment was superior for postoperative adjuvant chemotherapy were reported in Japan. Both studies showed that relapse-free survival and overall survival (OS) at 5 years after surgery were similar for a combination of cyclophosphamide, methotrexate, and 5-fluorouracil and for tegafur/uracil. Many chemotherapeutic agents that are used to treat recurrent or metastatic breast cancer have not yet been approved in Japan. As for molecular targeted therapy, some agents that target the human epidermal growth factor receptor family have been approved in Japan, whereas angiogenesis inhibitors have not. The results of many clinical trials have been incorporated into clinical practice in Japan, therefore, the outcomes of breast cancer therapy have surpassed those in other countries. Many pivotal clinical trials have been conducted outside Japan. Treatment regimens that have been developed on the basis of these studies might be suitable for the management of breast cancer in Western women, but not for Japanese women because of differences in genetic factors, physique, body mass index, pharmacokinetics, and drug metabolism. Such regimens should be modified on the basis of the characteristics of breast cancer in Japan to develop treatment that is optimally suited for Japanese women. In particular, local studies of pharmacokinetics, pharmacodynamics, and optimal dose levels and treatment intervals should be carefully performed. The establishment of treatment regimens optimally suited for Japanese patients with breast cancer could put the brakes on the trend towards increasing mortality from breast cancer in Japan.

Oral fluoropyrimidine may augment the efficacy of aromatase inhibitor via the down-regulation of estrogen receptor in estrogen-responsive breast cancer xenografts

The present preclinical study was designed to evaluate a new combination therapy comprised of the aromatase inhibitor anastrozole (ANA) and the oral fluoropyrimidines, UFT and S-1 against the estrogen receptor (ER)-positive human breast cancer cell line MCF-7/Arom 14, which was stably transfected with the cDNA of human aromatase. MCF-7/Arom 14 cells showed a high aromatase activity and notably were able to grow in the presence of testosterone and estradiol (E(2)) in vitro. ANA and 5-fluorouracil (5-FU) inhibited cell growth at concentrations of 0.005-10 and 0.2-5 μM, respectively, and the combination of both drugs additively inhibited cell growth. The growth of MCF-7/Arom 14 tumors was significantly inhibited by ANA and S-1 or UFT in vivo. The combination of ANA with S-1 or UFT administered using a 21-day consecutive, metronomic-like regimen significantly enhanced the antitumor efficacy, suppressing tumor growth for 2-4 times longer than monotherapy. To investigate the mechanisms by which S-1 enhances the antitumor activity of ANA, the protein and mRNA expression levels of ER-α in tumor tissue after treatment with S-1, ANA, and the typical chemotherapeutic agents doxorubicin (ADM) or paclitaxel (TXL) were analyzed. The protein and mRNA expression levels of ER-α in the tumor tissue were markedly decreased after treatment with S-1 or S-1 + ANA, but not after treatment with either ADM or TXL. The reduced ER-α level after S-1 treatment might contribute to the increased antitumor activity of ANA by reducing ER-α-induced growth signaling in addition to the decrease in estrogen production induced by ANA. Based on these results, the combination of ANA and S-1 might yield a greater benefit than other chemotherapeutic agents in postmenopausal women with ER-positive breast cancer.