Abstract OT1-1-08: Clinical outcomes among ErbB2+ MBC patients treated with lapatinib-capecitabine after trastuzumab progression: Role of early switch to lapatinib (TYCO study)

Background: Lapatinib in combination with capecitabine is a standard of care treatment for ErbB2+ metastatic breast cancer (MBC) patients who have progressed after anthracyclines, taxanes and trastuzumab treatment. Results from the lapatinib pivotal trial showed that the addition of lapatinib to capecitabine increased median time to progression (TTP) even among heavily pre-treated patients (median of 4 prior lines of therapy). A post-hoc exploratory sub-group analysis of this trial suggested that earlier administration of lapatinib-capecitabine in MBC patients who progress after trastuzumab may produce better clinical outcomes. The TYCO study was designed to evaluate if early initiation of lapatinib-capecitabine in patients with ErbB2+ MBC who have progressed on trastuzumab-containing regimen improves TTP in comparison with a delayed start of the therapy.

Trial design: TYCO is an international, multicenter, prospective, observational study in 269 ErbB2+ MBC patients whose disease has progressed after treatment with trastuzumab in the metastatic setting. Two cohorts will be compared; Group 1: patients receiving lapatinib-capecitabine just after the first trastuzumab progression, and Group 2: patients receiving lapatinib-capecitabine after two or more lines of treatment after first trastuzumab progression. The study duration is of 12 months with data collection at baseline and approximately every 3 months thereafter.

Major Eligibility Criteria: 1. Females ≥18y with confirmed ErbB2+ MBC who have progressed after a previous trastuzumab-containing regimen,2. Pts eligible for standard therapy with lapatinib-capecitabine at approved conventional doses, as per local approved label.3. Pts eligible to start standard treatment with Lapatinib-capecitabine at conventional doses, or receiving standard treatment with Lapatinib-capecitabine at conventional doses, for no longer than 10 weeks from the start of the treatment to the date of inclusion in the study;

Aims: Primary objective of this study is to determine if early switch to lapatinib-capecitabine in patients with ErbB2+ metastatic breast cancer who have progressed on trastuzumab containing regimen improves time to disease progression as determined by treating physician either clinically or radiologically. Secondary objectives include overall response rate and overall survival.

Statistical Methods: Kaplan-Meier plots will be used to describe the median TTP after start of lapatinib-capecetabine. Cox proportional hazard model will be developed to estimate the adjusted hazard ratio (and 95% confidence intervals) comparing TTP for the two treatment group using propensity score methods (trimmed sample, adjustment for the continuous propensity score measure, and doubly robust adjustment) to adjust for potential confounding by indication that may arise due to the non-randomised design.

Present and Target Accrual: Enrollment began in February 2010, and as per May 2012, 266 patients have been included from Turkey, Venezuela, Argentina, Saudi Arabia and Colombia.

Perpetuation of subgingival biofilms in an in vitro model

This study evaluated the reproducibility of in-vitro-grown biofilms, initiated with subgingival plaque from patients with periodontal disease, and continued through several cycles by re-inoculating new biofilms from previously grown biofilms. Subgingival plaque samples from bleeding pockets along with saliva samples were collected from three patients with chronic periodontitis and perpetuated through seven cycles. Calcium hydroxyapatite disks were coated with sterilized saliva inoculated with dispersed subgingival plaque. The biofilms were grown anaerobically at 37 degrees C for 10 days, and at specific intervals total viable bacteria were enumerated and the species present were analysed by DNA-DNA checkerboard hybridization. All cycles of biofilm growth occurred at similar rates and reached steady-state at day 7. No statistically or microbially significant differences were found for viable counts or species present, at the same period of maturation, among the different cycles. This study demonstrated that growth of certain target subgingival periodontal species in this biofilm model was reproducible and could be perpetuated in vitro through several cycles. The model could be useful in future studies to characterize different periodontopathogenic properties and biofilm interactions, especially in recolonization studies.

Differentiation of proximal bronchogenic carcinoma from postobstructive lobar collapse by magnetic resonance imaging. Comparison with computed tomography

MRI and CT studies in 18 patients with proximal bronchogenic carcinoma and postobstructive lobar collapse were analyzed retrospectively. The relative abilities of these imaging techniques to identify central tumor by a contour abnormality and to distinguish tumor mass from collapsed lung by CT attenuation values and MRI signal intensities were compared. MRI and CT were equivalent in their ability to identify a contour abnormality, both succeeding in 13 of 18 (72%) patients. CT was more successful than MRI in differentiating tumor mass from collapsed lung. Dynamic computed tomography scanning differentiated tumor from collapsed lung in eight of ten (80%) patients. MRI demonstrated different signal intensities of tumor and collapsed lung in 8 of 18 (44%) patients. T2-weighted images more often separated tumor from collapsed lung than other imaging sequences.

The binding and processing of plasminogen by Balb/c 3T3 and SV3T3 cells

The binding and processing of plasminogen by Balb/c 3T3 and SV3T3 cells was studied using 125I-labeled canine plasinogen. Throughout a 3-day period, 125I-plasminogen in the incubation medium bound to the cells and was degraded, first to intermediate-sized macromolecules that were the same size as the large (74,600-dalton) and small (25,000-dalton) chains of active plasmin, and to smaller fragments including 3-iodo-L-tyrosine. Binding to SV3T3 cells was independent of the protease-dependent morphological change (PDMC) characteristic of these and many other transformed cells. The SV3T3, and to a somewhat lesser extent, the 3T3 cells, both accumulated and released into the incubation medium 3-iodo-L-tyrosine, a terminal lysozymal digestion product. The results of a sublethal cell-surface trypsinization assay suggest that the cell-associated plasminogen was primarily bound to the surfaces of the 3T3 and SV3T3 cells while the macromolecular degradation products including active plasmin were inside the cells. The rate of 125I plasminogen degradation exhibited by SV3T3 cells was approximately two time greater than that of 3T3 cells, which presumably reflects differences in endocytosis or lysosomal hydrolysis, or both. The rates were unaffected by addition of pancreatic or soybean trypsin inhibitor sufficient to inhibit PDMC. In the incubation medium, plasminogen was activated to plasmin by SV3T3, but not by 3T3 cells. However, 95-100% of plasmin covalently bound to a 47,000-dalton canine serum component, which could be dissociated from plasmin by hydroxylamine: 95-100% of the plasmin was inactive to reaction with DF32P. Thus the serum component is a plasmin inhibitor. The plasmin-containing complex in the medium had an apparent molecular weight of 212,000. Under denaturing conditions, the complex dissociated into two covalently modified plasmin-containing species of 153,000 and 127,000 daltons. In addition to forming a complex with a serum component, the plasmin is cleaved into two small fragments (approximately 10,000 and 12,000 daltons) by as-yet uncharacterized serum factors.