May etanercept and PTH (1-34) association heal erosions in early rheumatoid arthritis? A pilot study

Rheumatoid arthritis (RA) is characterized by the formation in the joints of an inflammatory tissue, which causes the appearance of localized erosions on the margins of the joints. The molecular mechanism that causes the bone erosion is multifactorial. Inflammatory cytokines imbalance and OPG-RANK-L system are involved.

The aim of the study is to evaluate the possibility of inducing healing or reduction in the number of erosions in Rheumatoid Arthritis patients treated with anti-TNF-alpha adding Teriparatide (PTH1-34) to standard treatment with anti-TNF.

Twenty adult patients with active RA diagnosed according to American Rheumatism Association (ARA) criteria at least 6 months before study begin were enrolled. Only patients affected by established RA (6 to 18 months from symptoms beginning) were recruited. Eligible patients were randomized to receive a standard dosage of etanercept (50 mg/week) or etanercept at same dosage with an addition of teriparatide (20 mg). Evaluation of eventual healing of arthritic erosions by magnetic resonance imaging was performed at time zero and then at twelve months. The following evaluation was assessed at baseline and after 12 months according to the Outcome Measures in Rheumatology Clinical Trials (OMERACT) definitions: number of erosion and presence or absence of synovitis, effusion and bone oedema. A comparative examination of quantitative and qualitative assessment of each parameter was applied. Plain radiographs of the hands were obtained at baseline and 52 weeks. Radiographs were scored blindly using the van der Heijde modification of the Sharp method. Safety of each treatment was evaluated by means of the adverse events (AES) evaluation and report.

There were no significant differences in baseline characteristics between the groups. The study did not achieve its primary endpoint of healing erosions. In the active arm no healing of erosions was found. At 52 weeks, there were no new MRI erosions in two arms. Bone oedema scores were significantly improved at 52 weeks in favour of both treatments versus baseline scores, without inter-groups differences. X-ray patterns were unchanged in all patients of both groups. No new erosions or previous erosions' healing were observed. No AEs were reported. Patients from both groups demonstrated a significant reduction in the DAS 28 scores at 52 weeks (p < 0.005) if compared with baseline values.

These data confirm rapid control of inflammation and MRI damage benefits after Etanercept administration without a significant improvement in MRI findings after concomitant addition of teriparatide. Even though these results could seem to suggest to avoid the simultaneous use of these two drugs to treat RA erosions, further studies might be suggested to asses if sequential adminstration of an anabolic agent such as Teriparatide, after achieving clinical remission, may be able to improve bone damage.