Circulating Extracellular Matrix Fragments As Biomarkers in Myeloproliferative Neoplasms - Baseline Data from the Daliah Trial

Background Chronic bone marrow inflammation is associated with the myeloproliferative neoplasms (MPNs) and may lead to bone marrow failure due to accumulation of connective tissue in the bone marrow (myelofibrosis). The bone marrow stroma changes are elicited by an altered turnover of type I collagen and type III collagen (associated with ‘collagen’ and ‘reticulin’ fibrosis, respectively), leading to bone marrow fibrosis (BMF). Reducing or stabilizing BMF is considered a key therapeutic goal in MPNs. Non-invasive biomarkers that reflect collagen turnover have the potential to improve early detection of BMF and disease activity of MPNs and to monitor the disease modifying effect of treatment. In this study, non-invasive serological biomarkers of type I collagen synthesis (PRO-C1) and degradation (C1M) as well as type III collagen synthesis (PRO-C3) and degradation (C3M) were investigated in patients with MPNs. Methods PRO-C3, C3M, PRO-C1, and C1M were measured by ELISAs in pre-treatment serum from patients enrolled in the DALIAH trial (NCT01387763), a randomized phase III trial of hydroxyurea (HU) vs. pegylated interferon-α (IFN-α) in newly diagnosed or untreated patients with MPNs (n, subtypes: ET=49, PV=60, pre-PMF=8, PMF=13). Biomarker levels in patients with MPNs were compared to age- and gender-matched healthy individuals (n=32) by using unpaired t-test, and were assessed according to disease subtypes, somatic driver mutation status, and JAK2V617F allele burden using ordinary one-way ANOVA. Results PRO-C3 and C1M were significantly elevated in patients with MPNs (mean=61.18 ng/mL, mean=35.18 ng/mL, respectively) compared to healthy individuals (mean=49.79 ng/mL p=0.033, 95% CI=0.9343 , 21.93 and mean=28.83 ng/mL, p=0.016, 95%CI=1.188 , 11.52, respectively), whereas C3M was significantly decreased with a mean of 11.97 ng/mL compared to 14.76 ng/mL in healthy individuals (p=<0.0001, 95%CI=-3.898 , -1.677). PRO-C1 did not show any significant difference between MPN patients and healthy individuals. According to MPN subtypes, PRO-C3 was significantly elevated in patients with PMF (mean=88.52 ng/mL) compared to patients with ET (mean=56.10 ng/mL, p=0.0012, 95%CI=-54.51 , -10.33) or PV (mean=58.48 ng/mL, p=0.0024, 95%CI=-51.70 , -8.387). Higher C1M was observed in patients with PV (mean=38.19 ng/mL) compared to ET (mean=31.13 ng/mL) patients (p=0.0462, 95%CI=-14.04 , -0.082). No difference was observed in the collagen biomarker levels according to somatic driver mutation status. However, patients with high JAK2V617F allele burden (>50%) had a high disease activity and significantly higher levels of PRO-C3 and C3M (p=0.0397, 95%CI=0.4996 , 20.35 and p=0.0201, 95%CI=0.2636 , 3.021, respectively). Conclusion The collagen and reticulin turnover are altered in patients with MPNs, likely reflecting increased disease activity. The non-invasive fibrosis associated biomarker PRO-C3, was higher in patients with PMF as compared to ET or PV and in patients with JAK2V617F allele burden >50% indicating that PRO-C3 may be a marker of MPN disease severity. PRO-C3 and other serological collagen biomarkers, hold promise as useful non-invasive bone marrow fibrosis biomarkers to stratify and monitor the disease course in patients with MPNs.