Progression-free survival as surrogate end point for overall survival in clinical trials of HER2-targeted agents in HER2-positive metastatic breast cancer.

BACKGROUND: The gold standard end point in randomized clinical trials in metastatic breast cancer (MBC) is overall survival (OS). Although therapeutics have been approved based on progression-free survival (PFS), its use as a primary end point is controversial. We aimed to assess to what extent PFS may be used as a surrogate for OS in randomized trials of anti-HER2 agents in HER2+ MBC. METHODS: Eligible trials accrued HER2+ MBC patients in 1992-2008. A correlation approach was used: at the individual level, to estimate the association between investigator-assessed PFS and OS using a bivariate model and at the trial level, to estimate the association between treatment effects on PFS and OS. Correlation values close to 1.0 would indicate strong surrogacy. RESULTS: We identified 2545 eligible patients in 13 randomized trials testing trastuzumab or lapatinib. We collected individual patient data from 1963 patients and retained 1839 patients from 9 trials for analysis (7 first-line trials). During follow-up, 1072 deaths and 1462 progression or deaths occurred. The median survival time was 22 months [95% confidence interval (CI) 21-23 months] and the median PFS was 5.7 months (95% CI 5.5-6.1 months). At the individual level, the Spearman correlation was equal to ρ = 0.67 (95% CI 0.66-0.67) corresponding to a squared correlation value of 0.45. At the trial level, the squared correlation between treatment effects (log hazard ratios) on PFS and OS was provided by R(2) = 0.51 (95% CI 0.22-0.81). CONCLUSIONS: In trials of HER2-targeted agents in HER2+ MBC, PFS moderately correlates with OS at the individual level and treatment effects on PFS correlate moderately with those on overall mortality, providing only modest support for considering PFS as a surrogate. PFS does not completely substitute for OS in this setting.

Controversial issues in early-stage breast cancer: a global collaborative survey, supported by the European Society for Medical Oncology (ESMO).

BACKGROUND: To explore the current clinical management of early-stage breast cancer (BC) patients, identify areas of controversy, and interrogate how treating physicians implement latest advances. METHODS: We conducted a 27-item survey, disseminated in two stages: paper distribution at selected BC sessions at the ESMO 2012 Congress, and dedicated mailings to ESMO members. Descriptive statistical analysis and logistic regression analysis were applied to explore potential associations between the demographic characteristics of the participants and replies. RESULTS: A total of 512 physicians from 79 countries participated in the study, accounting for 465 (91%) fully completed questionnaires. The majority of the participants were ESMO members (66%), medical oncologists (86.5%), and working in multidisciplinary teams (91.6%). Heterogeneous results were captured, such as the following: 40.9% of the participants consider no genetic test useful for making adjuvant treatment decisions; 15.3% consider PET-CT a useful imaging modality for staging; 68.8% consider that postmenopausal patients with hormone receptor positive disease should always be offered an aromatase inhibitor as part of their adjuvant therapy; 78.7% prefer to administer trastuzumab concurrently with the taxane component of chemotherapy; and 27% would consider bevacizumab in the neoadjuvant setting. The logistic regression analysis did not identify any strong predictor of the probability of giving a reply fully compatible with evidence in the literature. CONCLUSION: This survey captures clinical practice and whether the latest research advances are implemented in the treatment of early-stage BC by an extended number of physicians. Significant individual differences were found. Areas of controversy were detected, and they deserve further exploration in order to generate 'tailored' educational tools, with the final goal being the standardization of the treatment of early-stage BC patients.

Pertuzumab: new hope for patients with HER2-positive breast cancer.

BACKGROUND: Human epidermal growth factor receptor 2 (HER2) overexpression is detected in approximately 15% to 20% of all breast cancers (BCs). A revolutionary change in the prognosis of this subgroup of patients has occurred since trastuzumab therapy was introduced into daily clinical practice. However, because trastuzumab resistance is common, new molecules with complementary and/or synergistic mechanisms of action have been developed. Pertuzumab is a new anti-HER2 humanized monoclonal antibody that prevents the formation of HER2 dimers. MATERIAL AND METHODS: A computer-based literature search was carried out using PubMed (keywords: breast neoplasm, dimerization, HER-2, pertuzumab); data reported at international meetings are included. RESULTS: This paper describes pertuzumab's mechanism of action, safety, and role in HER2-positive BCs. It also explores the role of pertuzumab as a single agent or combined with trastuzumab by reviewing data from preclinical research to ongoing clinical trials. Recently published trials, particularly the CLEOPATRA study, highlight the efficacy, tolerability, and increase in disease-free survival associated with this novel agent when combined with trastuzumab. CONCLUSION: The pertuzumab and trastuzumab anti-HER2 dual blockade is likely to represent a substantial advance for patients with HER2-positive BCs and a new milestone on the way to personalized medicine.