Purpose: p95HER2 is an NH 2 -terminally truncated form of HER2 that lacks the trastuzumab binding site and is therefore thought to confer resistance to trastuzumab treatment. In this report, we introduce a new antibody that has enabled the first direct quantitative measurement of p95HER2 in formalin-fixed paraffin-embedded (FFPE) breast cancer tissues. We sought to show that quantitative p95HER2 levels would correlate with outcome in trastuzumab-treated HER2-positive metastatic breast cancer.Experimental Design: The novel p95HER2 antibody used here was characterized for sensitivity, specificity, and selectivity over full-length HER2. Quantitative p95HER2 levels were measured in 93 metastatic breast tumors using a VeraTag FFPE assay to determine the correlation of p95HER2 levels with outcomes.Results: Within a cohort of trastuzumab-treated metastatic breast cancer patients, high levels of p95HER2 were found to correlate with shorter progression-free survival [hazard ratio (HR), 1.9; P = 0.017] and overall survival (HR, 2.2; P = 0.012) in patients with tumors selected to be HER2 positive by the VeraTag HER2 assay. For those with tumors found to be fluorescence in situ hybridization positive, elevated p95HER2 correlated similarly with shorter progression-free survival (HR, 1.8; P = 0.022) and overall survival (HR, 2.2; P = 0.009).Conclusions: We have successfully generated an antibody that can specifically detect p95HER2, and developed an assay to quantify expression in FFPE tumor specimens. Using this novel assay, we have identified a group of HER2-positive patients expressing p95HER2 that have a worse outcome while on trastuzumab. As p95HER2 retains sensitivity to kinase inhibitors, measurement of p95HER2 in breast tumor sections may be useful in guiding treatment for patients with HER2-positive breast cancer.Clin Cancer Res; 16(16); 4226-35. ©2010 AACR.

Summary Background Endoscopic band ligation (EBL) is used for primary (PP) and secondary prophylaxis (SP) of variceal bleeding. Current guidelines recommend combined use of non‐selective beta‐blockers (NSBBs) and EBL for SP, while in PP either NSBB or EBL should be used. Aim To assess (re‐)bleeding rates and mortality in cirrhotic patients receiving EBL for PP or SP for variceal bleeding. Methods (Re‐)bleeding rates and mortality were retrospectively assessed with and without concomitant NSBB therapy after first EBL in PP and SP. Results Seven hundred and sixty‐six patients with oesophageal varices underwent EBL from 01/2005 to 06/2015. Among the 284 patients undergoing EBL for PP, n = 101 (35.6%) received EBL only, while n = 180 (63.4%) received EBL + NSBBs. In 482 patients on SP, n = 163 (33.8%) received EBL only, while n = 299 (62%) received EBL + NSBBs. In PP, concomitant NSBB therapy neither decreased bleeding rates (log‐rank: P = 0.353) nor mortality (log‐rank: P = 0.497) as compared to EBL alone. In SP, similar re‐bleeding rates were documented in EBL + NSBB vs EBL alone (log‐rank: P = 0.247). However, EBL + NSBB resulted in a significantly lower mortality rate (log‐rank: P<0.001). A decreased risk of death with EBL + NSBB in SP (hazard ratio, HR: 0.50; P<0.001) but not of rebleeding, transplantation or further decompensation was confirmed by competing risk analysis. Overall NSBB intake reduced 6‐months mortality (HR: 0.53, P = 0.008) in SP, which was most pronounced in patients without severe/refractory ascites (HR: 0.37; P = 0.001) but not observed in patients with severe/refractory ascites (HR: 0.80; P = 0.567). Conclusions EBL alone seems sufficient for PP of variceal bleeding. In SP, the addition of NSBB to EBL was associated with an improved survival within the first 6 months after EBL.

Trastuzumab is effective in the treatment of HER2/neu over-expressing breast cancer, but not all patients benefit from it. In vitro data suggest a role for HER3 in the initiation of signaling activity involving the AKT–mTOR pathway leading to trastuzumab insensitivity. We sought to investigate the potential of HER3 alone and in the context of p95HER2 (p95), a trastuzumab resistance marker, as biomarkers of trastuzumab escape. Using the VeraTag® assay platform, we developed a dual antibody proximity-based assay for the precise quantitation of HER3 total protein (H3T) from formalin-fixed paraffin-embedded (FFPE) breast tumors. We then measured H3T in 89 patients with metastatic breast cancer treated with trastuzumab-based therapy, and correlated the results with progression-free survival and overall survival using Kaplan–Meier and decision tree analyses that also included HER2 total (H2T) and p95 expression levels. Within the sub-population of patients that over-expressed HER2, high levels of HER3 and/or p95 protein expression were significantly associated with poor clinical outcomes on trastuzumab-based therapy. Based on quantitative H3T, p95, and H2T measurements, multiple subtypes of HER2-positive breast cancer were identified that differ in their outcome following trastuzumab therapy. These data suggest that HER3 and p95 are informative biomarkers of clinical outcomes on trastuzumab therapy, and that multiple subtypes of HER2-positive breast cancer may be defined by quantitative measurements of H3T, p95, and H2T.Electronic supplementary materialThe online version of this article (doi:10.1007/s10549-013-2665-0) contains supplementary material, which is available to authorized users.