Investigating the discernible and distinct effects of platinum-based chemotherapy regimens for metastatic triple-negative breast cancer on time to progression

Randomised feasibility trial to compare three standard of care chemotherapy regimens for early stage triple-negative breast cancer (REaCT-TNBC trial)

INTRODUCTION

Despite the importance of chemotherapy in the treatment of early stage triple negative breast cancer (TNBC), no one optimal regimen has been identified. We conducted a pilot trial comparing outcomes for the three most commonly used chemotherapy regimens to assess the feasibility of conducting a larger definitive trial.

METHODS

Using integrated consent, newly diagnosed TNBC patients were randomised to one of three standard regimens: dose-dense doxorubicin-cyclophosphamide then paclitaxel, doxorubicin-cyclophosphamide then weekly paclitaxel or 5-FU-epirubicin-cyclophosphamide then docetaxel. Feasibility endpoints included; physician engagement, accrual rates, physician compliance and patient satisfaction with the integrated consent model. Our anticipated pilot trial sample size was 35 randomised patients in one year.

RESULTS

Between August 30th, 2016 and January 31st 2017, 2 patients met eligibility and were randomised. A survey of 10 participating oncologists was performed to identify potential strategies to enhance accrual. Most investigators (9/10) believed that the best regimen for TNBC was unknown, and 4/10 felt this was a pressing clinical question. Physicians' responses suggested that poor accrual was due to: a lack of interest in some study arms as oncologists already had a preferred regimen (4/10) and concerns about trial demands in busy clinics (3/10). The pilot feasibility endpoints were not met and the study was closed.

CONCLUSIONS

Despite initial interest in the trial question and multiple investigators agreeing to approach patients, this trial failed to meet feasibility endpoints. The reasons for poor accrual were multiple and require further evaluation if this important patient-centred question is to be answered.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02688803.

Effectiveness of Platinum-Based Treatment for Triple Negative Metastatic Breast Cancer: a Meta-Analysis

Background:

Triple-negative breast cancer (TNBC) is a sub-group of breast cancers with a particularly poor prognosis. The results of studies investigating the role of platinum-based chemotherapy (PBC) in metastatic TNBC (mTNBC) have been conflicting. In this meta-analysis, our aim was to assess the effectiveness of PBCs for mTNBCs.

Methods:

The PubMed, Cochrane Controlled Trials Register Databases, and EBSCOhost databases were accessed. The English language was used as the search language and only human studies were included. The Newcastle–Ottawa Quality Assessment Scale and the Jadad scoring system were used to evaluate the quality of the included randomized controlled studies.

Results:

Seven studies and 1,571 patients were included in this meta-analysis. The pooled hazard ratio (HR) for overall survival (OS), evaluated on the basis of six studies, showed the use of PBC regimes to be related to OS in mTNBCs (HR 0.620; 95% CI 0.513-0.749; p:<0.001). Four studies containing HR and abstract statistics used for HR calculation were included in the meta-analysis for progression-free survival (PFS). The pooled HR again indicated a significant relation (HR, 0.628; 95% CI, 0.501-0.786; p:<0.001).

Conclusions:

In this meta-analysis, we confirmed that PBC regimes provide OS and PFS advantages compared to non-PBC regimes. The use of PBC regimes could be a good choice in mTNBC patients for better quality of life and survival.

Enhancing accrual to chemotherapy trials for patients with early stage triple-negative breast cancer: a survey of physicians and patients

PURPOSE

The optimal chemotherapy regimen for patients with early stage triple-negative breast cancer (TNBC) remains unknown. The purpose of the study is to survey physicians and breast cancer patients about preferred chemotherapy regimens for early stage TNBC and clinical trial strategies.

METHODS

A standardised online questionnaire was developed and circulated to medical oncologists known to treat breast cancer. A separate questionnaire was given to patients who had received chemotherapy for breast cancer.

RESULTS

The questionnaire was completed by 41/84 medical oncologists (48.8% response rate) and 74 patients. The most commonly used neoadjuvant and adjuvant chemotherapy regimens for TNBC were dose-dense doxorubicin and cyclophosphamide (AC)-paclitaxel (P), dose-dense AC followed by weekly P and fluorouracil, epirubicin, cyclophosphamide-docetaxel (FEC-D). The majority of medical oncologists (80%) would be willing to enrol patients in trials evaluating the most effective chemotherapy regimen for TNBC. Oncologists favoured a three arm trial design comparing currently available standard of care treatments (36%) and trials of novel or non-standard of care agents 22% (9/41). Sixty percent (41/74) of patients indicated that they would be willing to be enrolled in trials evaluating various adjuvant regimens for TNBC. Both oncologists and patients were interested in novel consent approaches such as using the integrated consent model.

CONCLUSION

Optimisation of chemotherapy for TNBC is an important and unmet clinical need. It is apparent that various chemotherapy regimens are used for patients with early stage TNBC. The majority of medical oncologists and patients are interested in entering trials to optimise chemotherapy choices.

The Evolution of Triple-Negative Breast Cancer: From Biology to Novel Therapeutics

Triple-negative breast cancer (TNBC) is clinically defined as lacking expression of the estrogen receptor (ER), progesterone receptor (ER), and HER2. Historically, TNBC has been characterized by an aggressive natural history and worse disease-specific outcomes compared with other breast cancer subtypes. The advent of next-generation sequencing (NGS) has allowed for the dissection of TNBC into molecular subtypes (i.e., basal-like, claudin-low). Within TNBC, several subtypes have emerged as "immune-activated," consistently illustrating better disease outcome. In addition, NGS has revealed a host of molecular features characteristic of TNBC, including high rates of TP53 mutations, PI3K and MEK pathway activation, and genetic similarities to serous ovarian cancers, including inactivation of the BRCA pathway. Identified genetic vulnerabilities of TNBC have led to promising therapeutic approaches, including DNA-damaging agents (i.e., platinum salts and PARP inhibitors), as well as immunotherapy. Platinum salts are routinely incorporated into the treatment of metastatic TNBC; however, best outcomes are observed among those with deficiencies in the BRCA pathway. Although the incorporation of platinum in the neoadjuvant care of patients with TNBC yields higher pathologic complete response (pCR) rates, the impact on longer-term outcome is less clear. The presence of immune infiltrate in TNBC has shown both a predictive and prognostic role. Checkpoint inhibitors, including PD-1 and PD-L1 inhibitors, are under investigation in the setting of metastatic TNBC and have shown responses in initial clinical trials. Finally, matching emerging therapeutic strategies to optimal subtype of TNBC is of utmost importance as we design future research strategies to improve patient outcome.

Silencing of CXCR4 sensitizes triple-negative breast cancer cells to cisplatin

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer for which there is no effective treatment. Previously, we and others demonstrated that CXCR4 surface expression is an independent prognostic factor for disease relapse and survival in breast cancer. In this study, we investigated the effects of CXCR4 gene silencing on cisplatin chemosensitivity in human triple-negative breast cancer cell lines. We found that CXCR4 silencing significantly inhibited cell growth, decreased colony formation, and enhanced cisplatin sensitivity while overexpression of CXCR4 rendered cells more resistant to cisplatin. Moreover, the percentage of apoptosis and cell cycle arrest at the G2/M phase of cisplatin-treated CXCR4 knockdown cells was significantly higher than control cells. Furthermore, we demonstrated CXCR4 knockdown cells showed lower levels of mutant p53 and Bcl-2 protein than the control group, while also having higher levels of caspase-3 and Bax. However overexpression of CXCR4 had the reverse effect. In vivo experiments confirmed that downregulation of CXCR4 enhanced cisplatin anticancer activity in tumor-bearing mice, and that this enhanced anticancer activity is attributable to tumor cell apoptosis. Thus, this study indicates that CXCR4 can modulate cisplatin sensitivity in TNBC cells and suggests that CXCR4 may be a therapeutic target for TNBC.

Platinum-based chemotherapy in triple-negative advanced breast cancer

The purpose of this study was to evaluate the efficacy of platinum-based chemotherapy (PBC) versus conventional non-PBC regimens in a metastatic triple-negative breast cancer (TNBC) setting. We reviewed the electronic patient records of patients with confirmed metastatic TNBC at four major cancer centres in Canada. All patients were allocated into two groups based on type of chemotherapy received (PBC vs. non-PBC) and line of treatment (first-, second-, or third-line). The primary objective of this study was to evaluate the efficacy of PBC in metastatic TNBC in terms of median duration of overall survival (OS) from diagnosis of distant metastatic disease and compare it with the efficacy of conventional non-platinum-based chemotherapy in metastatic TNBC after controlling for known prognostic factors. A total of 153 metastatic TNBC patients were identified, 58 treated with PBC and 95 with non-PBC. The median time in first-line PBC versus non-PBC was not different between the two groups (2 vs. 2 months, p = 0.9), the median time on treatment in second and third-line therapy was longer for the PBC group compared to the conventional treated group (4 vs. 1 months, p = 0.004; 4 vs. 0.5 months, p = 0.004, respectively). Patients who received PBC had a longer OS compared to those managed conventionally (14.5 vs. 10 months, p = 0.041). This study evaluates the survival outcomes in a homogenous group of TNBC metastatic patients treated with or without PBC. Our results confirmed our hypothesis of a better OS among PBC-treated TNBC patients compared to conventionally managed TNBC patients. Currently ongoing Phase III trials assessing the benefit of PBC versus other chemotherapeutic regimens in advanced TNBC will help define the role of these agents for the management of this breast cancer subtype.