The Soluble Urokinase-Type Plasminogen Activator Receptor as a Biomarker for Survival and Early Treatment Effect in Metastatic Colorectal Cancer

SIMPLE SUMMARY: Patients with metastatic colorectal cancer are likely to have a poor outcome. Chemotherapy is the primary treatment, but because of toxicity and a lack of benefit for a large group of patients, it is important to monitor the treatment effect. The only tool for evaluating treatment effect currently is imaging. Biomarkers associated with disease progression could therefore be important for treatment monitoring in the future. The biomarker suPAR is prognostic for the overall survival in colorectal cancer. This study aimed to investigate if plasma suPAR levels before and during treatment were prognostic of survival and predictive for treatment effect. Our study confirmed that higher plasma suPAR levels before initiation of palliative chemotherapy were prognostic of shorter survival. ABSTRACT: The soluble urokinase-type plasminogen activator receptor (suPAR) is prognostic for overall survival (OS) in colorectal cancer (CRC). Our study explored the association between baseline suPAR and OS and progression-free survival (PFS) in metastatic CRC (mCRC). It is also the first study to explore the association between the initial change in suPAR level and OS, PFS and the first CT response evaluation. The study included 132 patients with mCRC treated with chemotherapy (FOLFIRI) with or without an EGFR-inhibitor. Blood samples were drawn before the first treatment cycle and in between the first and second treatment cycle. suPAR levels were determined using an ELISA assay. Using the Kaplan-Meyer method, we demonstrated a significantly shorter OS for patients with suPAR levels above the median (HR = 1.79, 95%CI = 1.10–2.92, p = 0.01). We also showed association between plasma suPAR level, gender and performance status (PS). However, we could not show any association with PFS, and analysis on the change in suPAR level provided no significant results. The results showing association between baseline suPAR and OS are in line with previous findings.