High expression levels of CD90 to predict edema response to steroid treatment in glioblastoma multiforme (GBM) patients.

Abstract

e13008 Background: GBM is the most aggressive brain tumour in the adult, with a median overall survival about 15 months. Patients usually present with many symptoms due to edema in addition of symptoms derived from the increasing tumour mass. Edema- dependent symptoms are currently treated with steroids. However, a number of patients do not respond to this therapy and almost all develop severe adverse effects. Currently, there is no biomarker that allows neuro-oncologists to predict edema response to steroid therapy. Methods: This is an observational study aimed to identify molecular markers based on massive expression analysis to predict edema response to steroids in patients diagnosed with GBM. Patients received dexamethasone (4mg bid) before surgery when high-grade glioma was suspected in contrast-enhanced brain MRI. 7 days later a second brain MRI was performed just before surgery to evaluate edema response according with RANO criteria. We collected neurological examinations at days -7 and -1 before surgery, surgical morbidity and time- to- recovery. Expression patterns (proliferative vs. mesenchymal) and a library of molecular markers related to both glioma-initiating cells and more differentiated cells from tumour mass were explored in tumoral and matched control samples from this cohort. Finally, we compared the expression levels of the selected molecular markers together with edema- responses after steroid therapy measured by brain MRI as well as with clinical values. Results: We recruited 54 patients and observed 32 edema- responses. We found that CD90 expression levels similar or above controls correlates with MRI response to steroids. Symptoms improvement and GBM resection without clinical worsening (p = 0.016). Nonetheless, we did not observed any association between CD90 expression level below controls and lack of response. Interestingly, we have observed that steroid responsiveness is not related with the proliferative and mesenchymal nature of the tumour. Conclusions: CD90 expression is a good predictor of edema response to dexamethasone and may be useful to identify candidates for steroid therapy.