The findings support previously reported results showing the efficacy of 1- and 3-year treatment regimens with denosumab, a monoclonal antibody against the receptor activator of nuclear factor κβ ligand, suggesting “[d]enosumab is a highly useful therapeutic agent for osteoporosis in patients with PBC,” say the researchers in a poster at The Liver Meeting 2023, held in Boston, Massachusetts, USA.

Yoshitaka Arase (Tokai University School of Medicine, Isehara, Japan) and colleagues randomly assigned 21 patients with PBC to receive 60 mg of denosumab every 6 months and 20 to receive zoledronic acid (ZOL) 5 mg once a year.

The participants were women aged a mean 68 to 69 years, of whom 98% were taking ursodeoxycholic acid and 20–33% bezafibrate. Baseline mean alkaline phosphatase (ALP) levels were 347.5 IU/L and total bilirubin levels were 0.8 mg/dL.

At 12 months, bone mineral density (BMD) at the lumbar spine had increased significantly in both treatment groups, by 7.5% with denosumab and 6.4% with ZOL from a mean 0.74 g/cm² at baseline. The between group difference was a mean of 1.1%, which was within the noninferiority margin of 2.4%, the investigators report.

While there were also significant increases with both treatments in total BMD at the hip, from a baseline mean of 0.62 g/cm², denosumab was not inferior to ZOL, with a reduction of 5.0%, versus 2.6% with ZOL, giving a between group difference of 2.4%.

There was a significant decrease in the ratio of serum ALP to upper limit of normal in both groups, but the rates of change did not differ significantly, at 24.8% with denosumab and 23.1% with ZOL. Similarly, markers of bone turnover – tartrate-resistant acid phosphatase 5b and bone-type ALP – significantly decreased in both groups to a similar degree, at 52.9% versus 49.6% and 45.0% versus 36.9%, respectively

Arase et al note that the adverse event rate was significantly lower among patients in the denosumab arm, at 14.3% versus 50.0% among those in the ZOL arm. The biggest difference was in the number of patients experiencing fever, occurring in seven patients in the ZOL group, compared with none of those in the denosumab arm.