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Gene expression profiling in germ cell tumors.

4522 Background: Germ cell tumors (GCT) are highly curable. Nevertheless, some patients relapse because of persistent tumor cells. Surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectrometry, a proteomic technology, can detect tumor-associated proteins and diagnose cancer based on the proteomic profiles of serum. We performed this study to detect serum tumor-associated proteins with SELDI-TOF and identify patients with viable tumor cells post GCT chemotherapy. Our long-term goal is to differentiate curable versus persistent tumor after chemotherapy. An additional goal is to identify those bio-markers associated with resistance to chemotherapy.


METHODS
SELDI-TOF analysis of serum was performed to determine the proteomic patterns. The training cohort included patients with active GCT and patients who were disease-free for more than 2 years (NED). Based on the proteomic patterns derived from the training cohort, a prediction system will be developed. The subsequent test cohort will include patients with masked disease status. It will be used to validate the accuracy of the prediction of disease status from the training cohort.


RESULTS
We plan to enroll 50 patients (25 NED, 25 active GCT) in the training cohort. Thus far, SELDI-TOF analysis has been performed in 20 patients from the training cohort (13 NED, and 7 GCT). Detail data analysis has been performed on 9 samples (5 NED, and 4 GCT). After baseline subtraction and noise reduction, total 2700 significant peaks were selected out of 56253 points. Nineteen peaks were found to differentiate patients with or without GCT when the absolute t-test value was set at 4. The proteomic patterns were highly homogenous in each group, but significantly different between the active GCT and NED groups.


CONCLUSIONS
SELDI-TOF has the potential to differentiate patients with or without active GCT. It may be possible to identify those patients with residual disease after chemotherapy and better determine their subsequent therapy. No significant financial relationships to disclose.