The average decrease of the three biomarkers with a threshold of 10% appears to be the best parameter to distinguish patients with progressive disease from other patients. breast malignancy patients treated with trastuzumab in combination with paclitaxel. Evaluation of the disease was performed according to the Response Evaluation Criteria in Solid Tumor (RECIST) at day 90. Results Patients with progressive disease at day 90 had smaller relative changes between day 1 and day 30 than those with complete, partial or stable responses at day 90: -9% versus -38% for sHER2 (P = 0.02), +23% versus -17% for CA15.3 Z-Ile-Leu-aldehyde (P = 0.005) and +29% versus -26% for CEA (P = 0.02). Patients with progressive disease at day 90 were less likely than the other patients to have a relative decrease of 20% in their biomarker levels at day 30: 6% vs 33% for sHER2 (P = 0.03), 0% vs 27% for CA15.3 (P = 0.03), 4% vs 29% for CEA (P = 0.04). No individual with progressive disease at day 90 experienced 20% reduction of the average combined biomarker levels at day 30 whereas 63% of the other patients experienced (P = 0.003). Moreover, when we analyzed a 10% reduction of the average biomarker levels no patient with progressive disease at day 90 experienced a decrease 10% at day 30 whereas 78% of other patients experienced (P 0.001, Se = 100%, Sp = 78%). Conclusion We show that regular measurement of sHER2, CA15.3, and CEA levels is useful for predicting the therapeutic response and for monitoring HER2-targeted therapy in patients with HER2-positive metastatic breast cancer. The average decrease of the three biomarkers with a threshold of 10% appears to be the best parameter to distinguish patients who go on to have progressive Z-Ile-Leu-aldehyde disease from those who will have a complete, partial or stable response. Introduction Breast cancer is the most frequent malignancy in women; over a million new cases are diagnosed Rabbit Polyclonal to ZNF420 per year worldwide and thus this is an important health issue [1]. The transmembrane receptor tyrosine kinase HER2 (human epidermal growth factor receptor 2) is usually overexpressed in approximately 15% Z-Ile-Leu-aldehyde of breast tumors [2], and this overexpression is usually linked to poor clinical prognosis and disease progression [3]. Determination of HER2 status has become a necessary step in breast cancer diagnosis that is important not only for the prognosis but also for the choice of therapy. HER2 protein expression is usually most commonly measured in routine practice by immunohistochemistry. HER2-positive breast cancers respond to anti-HER2 treatments, particularly to monoclonal antibodies such as trastuzumab, which have significantly improved the prognosis for patients with non-metastatic and metastatic disease [4, 5]. The serum markers used most widely to predict clinical response to trastuzumab-based anti-HER2 therapy (hybridization) first line metastatic breast cancer were recruited for any prospective evaluation of CEA, CA15-3 and sHER2 on treatment response prediction. In this study, we included patients with metastases who had not previously been treated and patients with metastases who experienced previously received treatment for their primary tumors. All the patients had been treated with a combination of trastuzumab (4 mg/kg on week 1, followed by 2 Z-Ile-Leu-aldehyde mg/kg/week) and paclitaxel (175 mg/m2 every 3 weeks or 80 mg/m2/weekly, 6 weeks/8) until progression or unacceptable toxicity. Evaluation of the disease was performed according to the Response Evaluation Criteria in Solid Tumor (RECIST). Inclusion criteria for these patients (IC) were: first collection metastatic breast malignancy measurable according to RECIST or not measurable (bone metastases, isolated pleural effusion) (IC 1), overall performance index (WHO) 2 (IC 2), life expectancy 3 months (IC 3), overexpression of HER2 (level 3+ by immunohistochemistry or 2+ by immunohistochemistry associated with positive.