VIENNA — "These are exciting times in the field of finger polyarthritis, as there are new data that help us better understand and possibly treat arthritis in the hands," said Margreet Kloppenburg, MD, PhD, professor of rheumatology at Leiden University in Leiden, the Netherlands, at the European Alliance of Associations for Rheumatology (EULAR) 2024 Annual Meeting.

A promising approach for the erosive form of finger polyarthritis is treatment with an osteoporosis medication: The monoclonal antibody denosumab, which targets the receptor activator of nuclear factor-kappa B ligand. The corresponding study was also mentioned by Willem Lems, MD, PhD, professor of immunology at the University of Amsterdam, Amsterdam, in a session on osteoporosis.

Finger Polyarthritis Common 

Finger polyarthritis often takes a back seat to arthritis of the knees and hips, which is why Kloppenburg referred to it as a "forgotten disease." It is not a rarity, however. "Up to 10%-25% of older women suffer from it."

The term "hand arthritis" may be misleading. "It sounds so simple, as if it were just one joint," said Kloppenburg. In fact, it is mostly a polyarticular disease that affects various finger joints, usually middle and end joints, and the thumb saddle joint.

Arthritis leads to deformities, painful movement restrictions, and sometimes erosive joint changes. "This is seen in around 10% of people with symptomatic, radiologically detectable finger polyarthritis, often accompanied by inflammation," said Kloppenburg.

Inadequate Therapeutic Options 

Treatment is based on nonpharmacologic measures: Education, exercise therapy, and orthoses for rhizarthrosis. The current EULAR guideline from 2018 recommends topical and oral nonsteroidal anti-inflammatory drugs, potentially paracetamol, intra-articular glucocorticoids, weak opioids such as tramadol, and chondroitin sulfate for pharmacologic therapy.

The guideline advises against the use of disease-modifying antirheumatic drugs, specifically biologics, in rheumatology, even though finger polyarthritis sometimes presents with synovitis, and there is evidence of the effectiveness of methotrexate in this indication.

"What we really lack are medications that can stop, reverse, or prevent structural damage," said Kloppenburg. In other words, disease-modifying osteoarthritis drugs are needed. The understanding that there are apparently different endotypes of arthritis helps in the search for potentially suitable agents. "The best known are synovitis-driven, cartilage-driven, and bone-driven endotypes."

"We know that osteoclast and osteoblast activation play a role in arthritis, and that's also what we see in erosive finger polyarthritis," said Kloppenburg. Studies suggest that osteoclasts resorb the subchondral bone, leading to bone remodeling at the cartilage interface. MRI studies, such as a meta-analysis with data from nearly 2000 patients, support this observation. "There is an association between these subchondral bone lesions and local joint tenderness," said Kloppenburg.

These findings appear to be clinically relevant. "Bone marrow lesions are also associated with radiographic progression," said Kloppenburg.

There seems to be a link to osteoporosis, she added, describing long-term data from the population-based Rotterdam Study over 4-8 years. "Especially patients with vertebral fractures at study baseline had a higher incidence of finger polyarthritis over time."

Can Denosumab Help?

Could osteoporosis medications help? That question was exactly what researchers from Belgium investigated in a randomized, placebo-controlled phase 2a study. They enrolled 101 patients with at least one erosive or pre-erosive interphalangeal joint, a soft swelling in at least one interphalangeal joint with ultrasound evidence of synovitis, and temporary inflammatory activations. Over 48 weeks, participants received subcutaneous denosumab or placebo every 12 weeks.

The primary endpoint was the change in the Ghent University Scoring System at week 24. The semiquantitative score developed specifically for finger polyarthritis combines radiologic signs of progressive erosion and repair. A significant improvement was achieved, which was even more pronounced after 48 weeks.

"What I find promising is that the number of new erosive joints after 48 weeks in the denosumab group was lower than in the placebo group," said Kloppenburg. Erosions first appeared in nine joints in the denosumab group, compared with 38 in the placebo group.

"This is a really exciting study," said Kloppenburg, despite one disappointment. "Unfortunately, they could not demonstrate an improvement in pain and function." The difference on the numerical rating scale from 0 to 10 was only 0.3 points in favor of denosumab at week 24, which was not significant. Kloppenburg attributed it to the study design and suggested new randomized controlled studies with pain as an outcome.

"It was only about radiologic changes," said Lems, who also found the study "quite remarkable," especially "in a disease where we do not have many treatment options."