IDH1-mutation and MGMT-promoter methylation are established prognostic markers in Glioblastoma multiforme (GBM); however, invasive procedures are needed to obtain the required tumor tissue. Metastasis-associated in colon cancer-1 (MACC1) can easily be measured in peripheral blood and has been established as a prognostic plasma marker for several solid cancer entities. Further, MACC1 has been identified by us and others as a promising biomarker for prognostication for GBM, when detected in the tumor tissue. Here, we evaluated whether circulating MACC1 transcripts could be useful to predict clinical outcome and response to therapy in GBM.

Plasma samples were collected from GBM patients (IDH1 wildtype (wt), IDH1R132H, and unspecified) before surgery. Samples from healthy volunteers served as controls. MACC1-transcript levels, determined by qRT-PCR, were correlated with patient overall survival (OS) and clinical data of known prognostic significance. Cut-off values for Kaplan-Meier analyses were determined by ROC calculations. Cluster analyses were performed.

MACC1 transcripts were higher in plasma of GBM patients compared to healthy controls (P<0.0001), yet differentially distributed within the cohort. Low MACC1 levels clustered together with all other favorable markers, i.e. small tumor volume, young age, IDH1R132H and MGMT promoter methylation. MACC1 levels correlated with patient prognosis in conjunction with the IDH mutation status: patients with IDH1R132H mutation and low MACC1 levels showed the most favorable outcome (mean OS 54.0 months (m), SD=9.8; 95% CI 34.7-73.3), those with IDH1wt and high MACC1 had the worst prognosis (mean OS 10.5 m), while those with IDH1wt and low MACC1 were intermediate (mean OS 20.3 m). No patients in this cohort displayed IDH1R132H and high MACC1 expression. Interestingly, patients with low MACC1 levels receiving standard therapy (operation and radiochemotherapy according to Stupp) survived longest (mean OS 36.9 m, SD=6.5; 95% CI 24.1-49.7). Patients with high MACC1 showed shorter OS (mean OS 13.0 m). The worst prognosis had patients not receiving the standard regimen, independently of their MACC1 levels (MACC1 low: 5.2 m; MACC1 high: 5.5 m).

The inclusion of circulating MACC1 transcript levels into the diagnostic workup might improve the accuracy of outcome prediction and thus help to define more precise risk categories of GBM patients. Whether pharmaceutical inhibition of MACC1 expression might be of general benefit for the treatment response and survival of GBM patients remains to be determined.

Citation Format: Carsten Hagemann, Nikolas Neuhaus, Mathias Dahlmann, Almut F. Kessler, Dennis Kobelt, Pia Herrmann, Matthias Eyrich, Benjamin Freitag, Thomas Linsenmann, Camelia Monoranu, Ralf-Ingo Ernestus, Mario Löhr, Ulrike S. Stein. Plasma levels of circulating MACC1 transcripts co-segregate with other prognostic markers and treatment response in glioblastoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5583.