Akt and mTORC1 signaling as predictive biomarkers for the EGFR antibody nimotuzumab in glioblastoma.
Michael W RonellenfitschPia S ZeinerMichel MittelbronnHans UrbanTorsten PietschDirk ReuterChristian SenftJoachim P SteinbachManfred WestphalPatrick N HarterPublished in: Acta neuropathologica communications (2018)
Glioblastoma (GB) is the most frequent primary brain tumor in adults with a dismal prognosis despite aggressive treatment including surgical resection, radiotherapy and chemotherapy with the alkylating agent temozolomide. Thus far, the successful implementation of the concept of targeted therapy where a drug targets a selective alteration in cancer cells was mainly limited to model diseases with identified genetic drivers. One of the most commonly altered oncogenic drivers of GB and therefore plausible therapeutic target is the epidermal growth factor receptor (EGFR). Trials targeting this signaling cascade, however, have been negative, including the phase III OSAG 101-BSA-05 trial. This highlights the need for further patient selection to identify subgroups of GB with true EGFR-dependency. In this retrospective analysis of treatment-naïve samples of the OSAG 101-BSA-05 trial cohort, we identify the EGFR signaling activity markers phosphorylated PRAS40 and phosphorylated ribosomal protein S6 as predictive markers for treatment efficacy of the EGFR-blocking antibody nimotuzumab in MGMT promoter unmethylated GBs. Considering the total trial population irrespective of MGMT status, a clear trend towards a survival benefit from nimotuzumab was already detectable when tumors had above median levels of phosphorylated ribosomal protein S6. These results could constitute a basis for further investigations of nimotuzumab or other EGFR- and downstream signaling inhibitors in selected patient cohorts using the reported criteria as candidate predictive biomarkers.
Keyphrases
- epidermal growth factor receptor
- tyrosine kinase
- phase iii
- small cell lung cancer
- advanced non small cell lung cancer
- clinical trial
- phase ii
- open label
- study protocol
- gene expression
- randomized controlled trial
- radiation therapy
- signaling pathway
- combination therapy
- transcription factor
- quality improvement
- replacement therapy
- newly diagnosed
- adverse drug
- placebo controlled
- radiation induced