The influence and clinical significance of proteasome inhibitor on serum bone metabolite markers in patients with myeloma bone disease

Abstract

Objective: To investigate the influence and clinical significance of proteasome inhibitor on serum bone metabolite markers including tartrate-resistant acid phosphatase 5b isoenzyme (TRACP-5b), type I collagen carboxy terminal peptide β(β-CTX), type I procollagen amino terminal prolongation peptide (PINP) and vitamin D3 in patients with myeloma bone disease (MBD). Methods: From April 2015 to June 2018, 68 patients with newly diagnosed MBD who admitted to our hospital were treated with proteasome inhibitor-based regimen. Serum concentration of TRACP-5b、β-CTX、PINP and vitamin D3 were measured before treatment and after 4 and 8 cycles of chemotherapy, and imaging changes were observed. Results: After 4 and 8 cycles of chemotherapy, serum levels of TRACP-5b, β-CTX and vitamin D3 were decreased significantly (P<0.05). The serum concentration of PINP was (78.1±44.9) ng/L before chemotherapy, while after 4 cycles, it turned to (94.5±56.1) ng/L without significant difference (t=-1.871, P=0.063). Moreover, it increased to (173.3±80.5) ng/L after 8 cycles of chemotherapy with significant difference (t=-8.272, P<0.001). The proportion of imaging classification ≥3 among all patients was 66.2%, and it decreased to 60.3% after 4 cycles of chemotherapy without significant difference (χ(2)=0.569, P=0.477). The proportion of imaging classification ≥3 after 8 cycles of chemotherapy decreased to 44.5%, which was significantly lower than that before treatment (χ(2)=6.260, P=0.012). After 8 cycles of chemotherapy, 63 patients were evaluable, of which 50 were effective and 13 were ineffective. Serum concentration of PINP in the effective group was higher than that in the ineffective group ((190.7±78.5) ng/L vs (106.5±47.3) ng/L,t=5.762, P<0.001), and the serum concentration of vitamin D3 in the effective group was lower than that in the ineffective group ((11.7±4.8) μg/L vs (15.6±5.5) μg/L, t=-2.478, P=0.016). The proportion of patients with more than grade 3 bone disease of the effective group was also significantly lower than that of the ineffective group (38.0% vs 69.2%, χ(2)=4.076, P=0.044). There was no significant difference in the serum concentration of TRACP-5b and β-CTX between two groups. Conclusion: After treatment with the proteasome inhibitor -based regimen, the serum concentrations of TRACP-5b, β-CTX and vitamin D3, which reflect osteoclast activity in MBD patients were decreased, the serum concentration of PINP indicating osteoblast activity was increased, and the grade of imaging of bone disease was decreased.