Abstract P1-13-09: Withdrawn

This abstract was withdrawn by the authors.

Abstract PD3-09: Pertuzumab and trastuzumab with or without metronomic chemotherapy for older patients with HER2- positive metastatic breast cancer: Results from the EORTC 75111- 10114 ETF/BCG randomized phase II study

Introduction: Pertuzumab (P) is approved as first line therapy for HER2-positive (HER2+) metastatic breast cancer (MBC) combined with trastuzumab (T) and docetaxel. However older patients are at higher risk of chemotherapy-induced toxicity raising high interest in a less toxic backbone such as metronomic chemotherapy and in chemo-free dual HER2 blockade (TP). Patients and Methods: This phase II selection study randomized (1:1) patients with HER2+ MBC, aged 70+ or frail 60+, to first line chemotherapy with metronomic oral cyclophosphamide 50 mg/day + TP (TPM) or TP alone. Prior endocrine therapy and up to 1 line of anti-HER2 therapy (without chemotherapy) for MBC were allowed.T-DM1 was offered in case of progression. Randomization was stratified according to hormonal receptors, previous anti-HER2 treatment and geriatric assessment. Primary endpoint was progression-free survival (PFS) rate at 6 months seeking a difference of ≥ 10% between the two arms. Results: Between July 2013 and May 2016, 39 and 41 patients were randomized to TP and TPM arm respectively: median age 76.7 years, hormone receptor positivity 69%, prior adjuvant T 11%, prior metastatic T (with endocrine therapy) 3%, visceral involvement 93.7%, potential frailty profile according to geriatric screening G8 (≤14) 71% and/or to short physical performance battery (<10) 81%, Charlson comorbidity score > 0 in 40%. With 20.7 months of median follow-up, 6-month and median PFS were 46.2% (95% CI 30.2-60.7) and 5.6 months (95% CI 3.6-16.8) versus 73.4% (95% CI 56.6-84.6) and 12.7 months (95% CI 6.7-24.8) for TP and TPM, respectively. Four patients in TPM and 2 in TP developed brain metastases only as progression event. OS and breast cancer specific survival were comparable between the two arms; 9/29 deaths were not breast cancer-related. Response rate was 44% in TP arm and 53% in TPM arm. In 29 patients who received T-DM1 second line, 6-month PFS, median PFS and response rate were 49.5% (95% CI 29.2-66.9), 5 months (95% CI 2.5-12.5) and 13.5%. In patients who discontinued TP(M), 37, 9 and 14 stopped because of progression, toxicity or other reasons, respectively. During TPM treatment, 1 patient died of heart failure and 1 developed grade 3 heart failure; 1 patient in each arm developed a ≥ 10% asymptomatic left ventricular ejection fraction decrease below 50%. Diarrhea any grade and grade ≥ 3 were observed in 56% and 8% versus 71% and 12% patients in TP and TPM arms, respectively. No grade 3 or febrile neutropenia was reported. There was no relevant difference in functional evolution between both groups. In the whole population, several geriatric items were of prognostic value by multivariate analysis: e.g. for OS, G8 >14 vs ≤ 14 HR=0.12 (95% CI 0.03-0.55, p 0.006). In 29 patients receiving T-DM1, grade 3 toxicity was rare: fatigue (2 patients), thrombocytopenia and epistaxis (1 patient). Conclusions: Metronomic chemotherapy-based dual blockade (TPM) seems to be superior to dual blockade alone (TP) in an elderly/frail HER2+ MBC population, with an attractive safety profile. TPM, followed by T-DM1 after progression, may delay or supersede taxane chemotherapy in this population.

Citation Format: Wildiers H, Tryfonidis K, dal Lago L, Vuylsteke P, Curigliano G, Waters S, Brouwers B, Aalders K, Meulemans B, Litiere S, Touati N, Cardoso F, Brain E. Pertuzumab and trastuzumab with or without metronomic chemotherapy for older patients with HER2- positive metastatic breast cancer: Results from the EORTC 75111- 10114 ETF/BCG randomized phase II study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD3-09.

A transatlantic perspective on the integration of immuno-oncology prognostic and predictive biomarkers in innovative clinical trial design

Immuno-therapeutics aim to activate the body's own immune system against cancer and are one of the most promising cancer treatment strategies, but currently limited by a variable response rate. Biomarkers may help to distinguish those patients most likely to respond to therapy; they may also help guide clinical decision making for combination therapies, dosing schedules, and determining progression versus relapse. However, there is a need to confirm such biomarkers in preferably prospective clinical trials before they can be used in practice. Accordingly, it is essential that clinical trials for immuno-therapeutics incorporate biomarkers. Here, focusing on the specific setting of immune therapies, we discuss both the scientific and logistical hurdles to identifying potential biomarkers and testing them in clinical trials.

Characterisation of multifocal breast cancer using the 70-gene signature in clinical low-risk patients enrolled in the EORTC 10041/BIG 03-04 MINDACT trial

BACKGROUND

In multifocal breast cancer, guidelines recommend basing adjuvant systemic treatment decisions on characteristics of the largest lesion, disregarding multifocality as an independent prognosticator. We assessed the association between multifocal disease and both the 70-gene signature (70-GS), and distant metastasis-free survival (DMFS) in clinical low-risk breast cancer patients enrolled in the European Organisation for Research and Treatment of Cancer 10041/BIG 03-04 Microarray In Node-negative and 1 to 3 positive lymph node Disease may Avoid ChemoTherapy (MINDACT) trial.

PATIENTS AND METHODS

The analysed population consisted of enrolled patients in the MINDACT trial with clinical low-risk disease, defined by a modified Adjuvant! Online cut-off for the 10-year risk of recurrent disease or death. Eligibility criteria of MINDACT dictate that patients with multifocal disease could be included if the different lesions had similar pathological characteristics. The presence of multifocal disease was deducted from the case report form (CRF)-question for sum of diameter for all invasive tumour foci. Clinicopathological characteristics and gene expression of patients with unifocal and multifocal (largest lesion) disease were compared. Subsequently, the association between multifocal disease and the 70-GS was evaluated as well as the association between multifocality and 5-year DMFS.

RESULTS

The study included 3090 clinical low-risk patients with unifocal and 238 patients with multifocal disease. Apart from a higher prevalence of lobular tumours (21.8% versus 10.8%, by local pathology), we did not observe differences in baseline characteristics between multifocal and unifocal tumours. Patients with multifocal tumours were more likely to be at high genomic risk as compared to patients with unifocal tumours (22.7% versus 17.3%, odds ratio [OR] 1.45, 95% confidence interval [CI] 1.02-2.07, P = 0.038). We did not find a significant association between tumour focality and DMFS (97.1% for unifocal versus 96.9% for multifocal, hazard ratio [HR] = 1.55, 95% CI 0.68-3.46, P = 0.172), nor a signal for a potential interaction between the prognostic effect of the 70-GS and focality of the tumour regarding DMFS.

CONCLUSION

In the group of clinical low-risk MINDACT patients, multifocal tumours were more likely to have a high-risk 70-GS profile compared to unifocal tumours. We did not observe a significant interaction between multifocality and the 70-GS with respect to survival without distant metastasis in these patients.

Abstract OT1-3-02: The treat CTC trial – A new approach targeting circulating tumor cells (CTC) in early breast cancer (EBC)

Background:

The presence of CTC in metastatic BC is associated with an impaired prognosis. Recent data show a reduced disease-free survival and increased risk of death in the presence of CTC in EBC. Therefore, patients with persisting CTC after (neo)adjuvant chemotherapy might benefit from additional systemic treatment.

Recent data have reinforced the hypothesis that trastuzumab can eliminate tumor cells by antibody dependent cell cytotoxicity (ADCC) or other immune mechanisms. Preclinical data have provided evidence that the benefit of trastuzumab may be associated with targeting cancer stem cells in a HER2 independent model (Ithimakin et al Cancer Res 2013). Trastuzumab eliminated CTC, irrespective of the HER2 status of the primary tumor and of CTC and this was associated with reduced relapses(Georgoulias et al Ann Oncol 2012).

Trial Design:

Treat CTC trial is a multicenter European randomized phase II trial, sponsored by the EORTC and run under the BIG umbrella. It will assess the efficacy of trastuzumab in eliminating persisting CTC after the completion of (neo)adjuvant chemotherapy and surgery in patients with HER-2-negative EBC. Eligible patients will be randomized in a 1:1 ratio to either 6 cycles of trastuzumab or observation. Patients’ peripheral blood will be tested again for CTC after 18 weeks.

Main Eligibility criteria:

- Adequately excised HER2-negative EBC

- Evidence of CTC detection using the CellSearch technology after completion of (neo)adjuvant chemotherapy

- Completion of adjuvant chemotherapy for node-positive disease or neoadjuvant chemotherapy with residual invasive disease in breast or lymph nodes (no complete pathological response)

- Histological Grade > 1 and primary tumor size > 1 cm

Specific aims:

The primaryobjective of the trial is to evaluate whether trastuzumab decreases the detection rate of CTC in patients with HER2-negative EBC by comparing the trastuzumab treated arm to the observation arm. Furthermore, clinical outcomes as measured by Recurrence Free Interval (RFI), Invasive Disease Free Survival (IDFS), Disease Free Survival (DFS) and Overall Survival (OS)) between the trastuzumab and observation arms will be compared.

Present accrual and target accrual:

Treat CTC started patient screening in April 2013 in Belgium. It is estimated that 2175 women will be registered to include 174 patients eligible for randomization. Accrual is expected to be completed in 2 years.

Methods:

The primary test will be a one-sided test to compare the trastuzumab arm to the observation arm for the CTC detection rate at week 18 (superiority test). The comparison for the primary endpoint will be performed on the intention-to-treat population using a one-sided test with overall a of 0.1. The odds ratio and its confidence interval will be estimated using a logistic regression model. The comparison of RFI, IDFS, DFS and OS will be done using a two-sided test in a proportional hazards model for cause specific hazard, adjusted for the stratification factors.

Perspectives:

Given the prognostic relevance of CTC in BC, the Treat CTC trial will be the first multicenter, randomized trial in which CTC are used to guide treatment decisions in EBC. The results of this trial will help to clarify the clinical utility of CTCs in early disease.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT1-3-02.