Palbociclib as single agent or in combination with the endocrine therapy received before disease progression for estrogen receptor-positive, HER2-negative metastatic breast cancer: TREnd trial.

Background: The activity of palbociclib as a single agent in advanced breast cancer has not been extensively studied, with the only available clinical data limited to heavily pretreated patients. Preclinical data suggests palbociclib may partially reverse endocrine resistance, though this hypothesis has not been evaluated in previous clinical studies. This phase II, open-label, multicenter study examined the activity of palbociclib monotherapy, as well as palbociclib given in combination with the same endocrine therapy (ET) that was received prior to disease progression, in postmenopausal women with moderately pretreated, estrogen receptor-positive, HER2 negative advanced breast cancer. Patients and methods: Eligible women with advanced disease which had progressed on one or two prior ETs were randomized 1 : 1 to receive either palbociclib alone, or palbociclib in combination with the ET as previously received. Primary end point was clinical benefit rate (CBR); secondary end points included progression-free survival (PFS). Results: Between October 2012 and July 2016, a total of 115 patients were randomized. The CBR was 54% [95% confidence interval (CI): 41.5-63.7] for combination therapy, and 60% (95% CI: 47.8-72.9) for monotherapy. Median PFS was 10.8 months (95% CI: 5.6-12.7) for combination therapy, and 6.5 months (95% CI: 5.4-8.5) for monotherapy [hazard ratio (HR) 0.69; 95% CI: 0.4-1.1, exploratory P-value = 0.12]. Exploratory analyses revealed the PFS advantage for combination therapy was seen in the subgroup of patients who received prior ET for >6 months (HR 0.53; 95% CI: 0.3-0.9, exploratory P-value = 0.02), but not in those who received prior ET for ≤6 months. Conclusion: Palbociclib has clinical activity as a single agent in women with moderately pretreated, oestrogen receptor-positive, HER2-negative advanced breast cancer. Palbociclib may have potential to reverse endocrine resistance in patients with a history of previous durable response to ET. Clinical trial information: NCT02549430.

Chemotherapy with or without trastuzumab.

The prognosis of pT1N0M0/stage I breast cancer has generally been considered so favourable that these patients are not routinely offered adjuvant systemic therapy. However, biological heterogeneity within pT1N0M0 dictates diverse outcomes within the subgroup. HER2 gene amplification or protein overexpression is uncommon in pT1N0M0 disease, but, when present, is clearly associated with a higher risk of recurrence. The role of anti-HER2 therapy in these patients is controversial. Few women with node-negative, small tumours were included in the adjuvant trastuzumab trials. There are no robust data on trastuzumab in this patient subset, although subgroup analyses suggest that proportional benefits are independent of T and N. With current guidelines and scheduling, committing to adjuvant trastuzumab involves concurrent chemotherapy, 1 year of treatment and potential cardiotoxicity. A further challenge with anti-HER2 therapy is the potential benefit in patients with demonstrable HER2 positivity within a predominantly HER2-negative tumour. The decision for therapy requires a yes/no answer, but HER2 status derives from a continuum of gene copy number and protein expression. The diagnostic threshold is made more complex by heterogeneity of the HER2 status within a tumour. This review focuses on available data for HER2-positive pT1N0M0 disease and explores the significance of intratumoural HER2 heterogeneity.

New strategies to identify molecular markers predicting chemotherapy activity and toxicity in breast cancer.

Despite significant improvements in the treatment and outcomes of early-stage breast cancer, the quest continues to find biological and molecular markers that would enable earlier diagnosis or better prediction of treatment efficacy and toxicity. Metabolomics--the latest and one of the most exciting of the 'omic' sciences--has shown early promise as a non-invasive diagnostic aid in ovarian cancer, and may allow the detection of subtle metabolic changes that could have diagnostic, prognostic or predictive value in breast cancer. Routine monitoring of circulating tumour cells (CTCs) has also been advocated as a novel means of detecting breast cancer progression earlier, and identifying alterations in tumour cells that might signal the need for therapy changes. Ongoing studies should help to answer important questions relating to the use of metabolomics and CTC evaluation as new strategies to monitor cancer progression and identify markers of chemotherapy activity and toxicity.

Feasibility and safety of dose-dense docetaxel after conventional epirubicin and cyclophosphamide as adjuvant treatment for early breast cancer patients.

BACKGROUND: Although dose-dense chemotherapy may reduce breast cancer recurrence and death, phase II studies show that dose-dense docetaxel is poorly tolerated following administration of dose-dense anthracycline-based chemotherapy mainly because of cutaneous toxicity. MATERIAL AND METHODS: This pilot study was designed to explore feasibility and safety of dose-dense docetaxel after conventional anthracycline-based therapy. Treatment consisted of sequential administration of 4 cycles of 3-weekly epirubicin (90 mg/m(2)) plus cyclophosphamide (600 mg/m(2)), followed by 4 cycles of bi-weekly docetaxel with pelfilgrastim on day 2 of each docetaxel cycle. Two docetaxel dose levels were planned: 75 mg/m(2) (D75) and 100 mg/m(2) (D100). Patients could only be assigned to the higher docetaxel dose if no early treatment discontinuations due to toxicity were seen, and a median relative dose intensity of docetaxel >90% among the first 5 evaluable patients was achieved. RESULTS: Fifty three patients received 4 cycles of epirubicin/cyclophosphamide (EC). Six patients withdrew from study before commencing docetaxel: four for toxicity, and two who declined further study participation. Eight patients, 2 in the first dose level and 6 in the second dose level, stopped treatment for toxicity after the first cycle of docetaxel and before densification. Therefore these events were not considered early treatment discontinuations. No patients required dose interruption after the second docetaxel administration. Overall 5 patients in the first dose level and 34 patients in the second dose level received 4 cycles of accelerated (dose-dense) docetaxel. No grade 3 or grade 4 toxicities occurred at the first dose level. No grade 4 toxicities occurred at the second dose level, while grade 3 toxicities occurring in >2 patients were myalgia and bone pain (5 and 8 patients respectively, 13% and 20%) and skin-nail toxicity (7 patients, 21%). No dose-reductions or significant treatment delays were required, translating to median relative dose intensity of 100% for docetaxel 75 mg/m(2), and 99% for 100 mg/m(2). CONCLUSIONS: Administration of docetaxel 100 mg/m(2) bi-weekly after conventional EC is feasible in selected early breast cancer patients. Lack of prior exposure to dose-dense anthracycline, as well as the use of stringent criteria implemented in the treatment protocol, might explain the improved safety profile and high treatment compliance observed in this study.