Association between post-operative hPG80 (circulating progastrin) detectable level and worse prognosis in glioblastoma

BACKGROUND

Patients with glioblastomas have a dismal prognosis, and there is no circulating predictive or prognostic biomarker. Circulating progastrin, hPG80, is a tumor-promoting peptide present in the blood of patients with various cancers that has been shown to have prognostic value. We evaluated the prognostic value of plasma hPG80 in patients with isocitrate dehydrogenase-wild type glioblastoma after surgery.

PATIENTS AND METHODS

A multicentric retrospective study in glioblastoma patients treated with standard radio-chemotherapy was conducted. The hPG80 levels were measured in plasma EDTA samples collected after surgery with an ELISA DxPG80.lab kit (Biodena Care, Montpellier, France), which has a detection threshold of 1.2 pM. The relationship between post-operative hPG80 plasma levels, in combination with other known prognostic factors, and patients' progression-free survival (PFS) and overall survival (OS) was evaluated.

RESULTS

Sixty-nine patients were assessable. Plasma samples were collected after tumor biopsy (B), partial resection (PR), and complete resection (CR) for 22, 25, and 22 patients, respectively. At a median concentration of 5.37 pM (interquartile range 0.00-13.90 pM), hPG80 was detected in 48 (70%) patients (hPG80+). CR was associated with significant lower values of hPG80 levels: the median value was 0.7 versus 9.1 pM for PR (P = 0.02) and 8.3 pM for B (P = 0.004). The hPG80 detection rate was also significantly lower: 50% (CR) versus 72% (PR) versus 86% (B) (P = 0.005). The median follow-up was 39 months [22.4 months-not reached]. hPG80 post-operative detection was associated with numerically shorter PFS (6.4 versus 9.4 months, P = 0.13) and OS (14.5 versus 20.9 months, P = 0.11). In multivariate analysis, hPG80 was a prognostic factor for OS (P = 0.034).

CONCLUSIONS

Circulating hPG80 could serve as a new prognostic biomarker after surgery in patients with glioblastoma treated with radio-chemotherapy.

Issues and limitations of available biomarkers for fluoropyrimidine-based chemotherapy toxicity, a narrative review of the literature

Fluoropyrimidine-based chemotherapies are widely used to treat gastrointestinal tract, head and neck, and breast carcinomas. Severe toxicities mostly impact rapidly dividing cell lines and can occur due to the partial or complete deficiency in dihydropyrimidine dehydrogenase (DPD) catabolism. Since April 2020, the European Medicines Agency (EMA) recommends DPD testing before any fluoropyrimidine-based treatment. Currently, different assays are used to predict DPD deficiency; the two main approaches consist of either phenotyping the enzyme activity (directly or indirectly) or genotyping the four main deficiency-related polymorphisms associated with 5-fluorouracil (5-FU) toxicity. In this review, we focused on the advantages and limitations of these diagnostic methods: direct phenotyping by evaluation of peripheral mononuclear cell DPD activity (PBMC-DPD activity), indirect phenotyping assessed by uracil levels or UH2/U ratio, and genotyping DPD of four variants directly associated with 5-FU toxicity. The risk of 5-FU toxicity increases with uracil concentration. Having a pyrimidine-related structure, 5-FU is catabolised by the same physiological pathway. By assessing uracil concentration in plasma, indirect phenotyping of DPD is then measured. With this approach, in France, a decreased 5-FU dose is systematically recommended at a uracil concentration of 16 ng/ml, which may lead to chemotherapy under-exposure as uracil concentration is a continuous variable and the association between uracil levels and DPD activity is not clear. We aim herein to describe the different available strategies developed to improve fluoropyrimidine-based chemotherapy safety, how they are implemented in routine clinical practice, and the possible relationship with inefficacy mechanisms.