Procollagen C-protein enhancer 1 (PCPE-1) as a potential serum biomarker for osteosarcoma.

Abstract

e23518 Background: Osteosarcoma (OS) is the most common bone malignancy in children and young adults. Treatment with perioperative systemic chemotherapy has improved patient outcome but a third of patients will eventually develop incurable metastatic disease. Currently, there are no biomarkers for monitoring patients’ response to neo-adjuvant (NA) chemotherapy or for patients under active surveillance following treatments. Procollagen C-Proteinase Enhancer-1 (PCPE-1) is an extra-cellular matrix glycoprotein which promotes the maturation of pro-collagen into collagen in various tissues. Elevated serum levels of PCPE-1 are found in bone diseases such as Paget’s disease and Osteoporosis and in patients with breast cancer with bone metastases. Serum PCPE-1 has not been described in patients with OS. We aimed to describe PCPE-1 serum levels in patients with OS compared with healthy volunteers, and across different time points in their treatment and disease course. Methods: We collected serum samples from the Israeli national biobank of 18 adult OS patients. Serum samples were also collected from 6 healthy individuals. Additionally, we obtained serial samples from 4 OS patients prior to and after initiating NA therapy. Quantification of serum PCPE-1 levels was performed using a commercially available enzyme-linked immunosorbent assay (ELISA) kit. Results: We successfully analyzed serum PCPE-1 levels from all patients and healthy volunteers. Mean PCPE-1 levels of 553ng/ml (range 479-614ng/ml) were observed in OS patients, compared with 313ng/ml (285-339ng/ml) in healthy volunteers. Of 4 patients undergoing treatment who had serial samples, a decrease in serum levels was observed 2 responding patients, while an increase in PCPE-1 levels were observed in one patient after NA treatment who had no response to treatment at the time of surgery. Of notice, serum levels nearly doubled in a patient during active surveillance who experienced local disease recurrence (274ng/ml and 423ng/ml, respectively). Conclusions: This is the first study to show elevated PCPE-1 serum levels in patients with OS. Our study also demonstrates potential changes in PCPE-1 levels in response to treatment. We are expanding our study to include a pediatric population to investigate the role of PCPE-1 as a potential tumor biomarker for monitoring treatment and surveillance of OS.