LONDON – Tumor necrosis factor may play a role in erosive hand osteoarthritis, and treatments such as etanercept that target this cytokine may help prevent progression of the condition, according to the results of two studies presented at the European Congress of Rheumatology.
In one of the studies, immunoscintigraphic detection of radiolabeled certolizumab pegol was used to show that tumor necrosis factor (TNF) was present in swollen finger joints. In another study, researchers looked to see if treatment with etanercept would have any specific effects on the joints of patients with erosive hand osteoarthritis (OA) and performed a separate analysis of the potential effect on synovitis and the effect on bone marrow lesions.
“We previously had the idea that TNF is an important cytokine in the pathogenesis of erosive [hand] osteoarthritis; but there have been no animal studies, and it’s very difficult to take biopsies or fluid aspiration from these small finger joints,” Dr. Ruth Wittoek, a staff rheumatologist at Ghent University Hospital in Belgium and a coauthor of all three studies, explained in a precongress interview. “We needed to look for other possibilities to really identify the presence of TNF in those affected joints.”
Dr. Wittoek and her associates used immunoscintigraphy to take static images of both hands of five patients with erosive OA immediately (less than 15 minutes) after administration of radiolabeled certolizumab pegol (early phase) and 4-6 hours following the injection (late phase).
The patients studied had erosive OA for a median of 8.4 years, and their median age was 55.6 years. All patients underwent clinical examination for presence of tenderness and palpable swelling of the joints and ultrasound 1 day prior to undergoing immunoscintigraphy.
All 18 interphalangeal (IP) finger joints were scored according to the anatomical phase scoring system on x-ray, and 90 IP finger joints were studied in total. The uptake of radiolabeled certolizumab pegol was semiquantitatively described as being absent, weak, or strong.
During the early phase following administration, uptake of the radiolabeled TNF inhibitor was seen in seven (7.8%) joints, although the uptake was described as weak in all cases. The radiolabeled TNF inhibitor was seen in 24 (26.7%) joints during the late phase following administration, with five instances described as strong uptake and the remaining 19 instances being weak uptake. No uptake of the radiolabeled TNF inhibitor was seen in metacarpophalangeal joints.
Uptake of the radiolabeled TNF inhibitor was linked to signs of disease activity, including tender, swollen, and radiographically active joints.
Late uptake was present in 12 (36.4%) of 33 tender joints and in 12 (21.1%) of 57 nontender joints (odds ratio, 2.1; 95% confidence interval, 0.8-5.6; P was nonsignificant).
The relationship was most pronounced with palpable joint swelling: Late uptake was present in 14 (61%) of 23 swollen joints and 10 (14.9%) of 67 nonswollen joints (OR, 8.9; 95% CI, 3.3-26.0; P less than .001).
Late uptake was present in 18 (29%) of 62 sonographically active joints (defined as any presence of effusion or synovial proliferation) but just 6 (21.4%) of 28 noninflamed joints (OR, 1.5; 95% CI, 0.5-4.3; P was nonsignificant).
Uptake of the radiolabeled TNF inhibitor was observed in all anatomical phases of erosive hand OA, Dr. Wittoek noted, but the strongest association was found during the final remodeling (R) phase.
“Soft-tissue swelling strongly correlated with uptake of certolizumab, meaning in these joints a lot of TNF was present,” Dr. Wittoek said. “These data further solidify the rationale for cytokine-directed therapies in erosive OA.”
Although the data provide proof of concept that TNF may be involved in erosive hand OA, the lack of a control tracer was noted as a limitation of the study after the investigator’s presentation. Dr. Wittoek conceded that it would be interesting to examine that in a future study.
So, if TNF is present, what effect does anti-TNF therapy have on the joints in erosive hand OA?
That question was addressed in a multicenter, double-blind, randomized, placebo-controlled trial involving 90 patients who were randomized to receive either 50 mg of subcutaneous etanercept weekly for 24 weeks, then 25 mg weekly for the remainder of 1 year (45 patients), or placebo (45 patients). Participants were a mean age of 60 years, 81% were women, and 96% fulfilled the American College of Rheumatology hand OA criteria.
“Synovial inflammation is often present in erosive hand OA; moreover, synovitis is associated with pain and with structural damage after around 2 and a half years,” the lead study author, Dr. Margreet Kloppenburg, a professor of rheumatology at Leiden University Medical Centre in the Netherlands, said in an interview.