Clinical utility of C-terminal telopeptide of type 1 collagen in multiple myeloma.

Myeloma bone disease (MBD) is a major cause of morbidity in multiple myeloma (MM). We investigated bone turnover markers (BTM) as relapse predictors and biomarkers for monitoring MBD. We measured C-terminal telopeptide of type I collagen (CTX-1), and Procollagen type 1 N Propeptide (P1NP) in 86 MM patients and 26 controls. CTX-1 was higher in newly diagnosed patients compared to control, remission and relapse (P < 0·05), and decreased following treatment. In the setting of relapse, a CTX-1 rise greater than the calculated least significant change (LSC) was observed in 26% of patients 3-6 months prior to relapse (P = 0·007), and in 60·8% up to 3 months before relapse (P = 0·015). Statistically significant changes in CTX-1 levels were also observed in patients who were with and without bisphosphonate therapy at the time of relapse. In patients with normal renal function, mean CTX-1 level was highest in the newly diagnosed group (0·771 ± 0·400 µg/l), and lowest in the remission group (0·099 ± 0·070 µg/l) (P < 0·0001). P1NP levels were not statistically different across the patient groups. We conclude that CTX-1, measured on an automated hospital laboratory platform, has a role in routine treatment monitoring and predicting relapse of MBD, even in patients on bisphosphonates.