Prognostic value of hPG80 (circulating progastrin) in IDH-wild type glioblastoma treated with radio-chemotherapy.

Abstract

2049 Background: hPG80 (circulating progastrin) is a protein secreted by many cancer types, playing a role in tumorigenesis by regulating cancer stem cells, angiogenesis, proliferation/differentiation and decreasing apoptosis. hPG80 is detectable in plasma of cancer patients and previous studies have shown its prognostic role in various cancers. Given the lack of circulating biomarker in glioblastoma, we evaluated the prognostic value of plasma hPG80 in patients with IDH wild type glioblastoma Methods: This multicentric retrospective study included IDHwt glioblastoma patients treated with standard radio-chemotherapy. The ELISA DxPG80.lab kit (Biodena Care, Lausanne, Switzerland) was used to measure hPG80 levels after surgery with a detection threshold of 1 pM in all plasma EDTA samples according to the manufacturer’s instruction. The prognostic impact of hPG80 was evaluated on patient’s progression-free survival (PFS) and overall survival (OS). Results: We included 70 patients (38 males /32 women) with a median age of 64 years (Range 19 - 84). Karnofsky index was > 70% in 52 (91%) of 57 evaluable patients. Tumor biopsy (B), partial resection (PR), complete resection (CR) were performed in 22, 25 and 23 patients respectively. MGMT promotor was methylated in 22 (40%) of the 55 evaluable patients. After surgery, hPG80 was detected in 48 (69%) patients (hPG80+) with a median concentration of 9.52 pM (IQR 5.21 - 21.20). Complete surgery was associated with undetectable levels of hPG80 (52% (CR) vs 28% (PR) vs 14% (B), p = 0.006) and lower concentration if hPG80+ (CR: 5.8 pM [IQR 1.92 - 11.38] vs PR: 12.84 pM [IQR 8.09 - 37.09]; p = 0.04 vs B: 9.86 pM [IQR 4.66 - 21.63]; p = 0.16). With a median follow-up of 39 months (22.4-NR), 86% of patients had progressed and 70% had died. In univariate analysis, hPG80 positivity was associated with PFS (5.6m vs 8.5m, p = 0.053) and OS (14.5 vs 22m, p = 0.04) in hPG80+ vs hPG80- patients respectively. hPG80+ patients with complete surgery had worse median OS than hPG80- patients (14.5 vs 22.0 m; p = 0.051 respectively. Cox proportional hazards model did not fit for covariate analysis. Conclusions: Our findings show that hPG80 could serve as a new circulating prognostic biomarker in IDHwt glioblastoma patients treated with radio-chemotherapy. Further explorations are ongoing in larger cohorts including longitudinal evaluation during the course of the disease.