Monitoring of serum Her-2/neu predicts histopathological response to neoadjuvant trastuzumab-based therapy for breast cancer.

Background: This prospective pilot study was performed to elucidate whether early changes in serum levels of the Her-2/neu extracellular domain (ECD) reflect histopathological response to trastuzumab-based neoadjuvant therapy in patients with Her-2/neu-overexpressing breast cancer.

Patients And Methods: ECD levels were measured throughout neoadjuvant trastuzumab-based treatment in 16 patients using a Her-2/neu Microtiter ELISA.

Results: In 9 (56%) patients with Her-2/neu shedding tumors (ECD > 15 ng/ml), ECD values (in % of baseline) of non-responders vs.

Monitoring of serum Her-2/neu predicts response and progression-free survival to trastuzumab-based treatment in patients with metastatic breast cancer.

Purpose: The present pilot study was performed to elucidate whether early changes in serum Her-2/neu extracellular domain (ECD) levels during trastuzumab-based treatment would predict the clinical course of disease in patients with metastatic breast cancer.

Experimental Design: Sera from 55 patients with Her-2/neu-overexpressing metastatic breast cancer obtained immediately before each weekly administration of trastuzumab were analyzed by a serum Her-2/neu ELISA.

Results: Whereas response rates were significantly higher in patients with elevated (>or=15 ng/ml) ECD levels before initiation of treatment (35% versus 7%, P = 0.