Ultrasound-detected inflammation and structural changes in the joints, tendons and entheses of patients with cancer who developed arthritis or arthralgia after exposure to immune checkpoint inhibitors.

OBJECTIVES

To explore the prevalence and distribution of ultrasound-detected inflammation and structural damage in the joints, tendons and entheses of patients who developed new-onset arthritis or arthralgia following exposure to immune checkpoint inhibitor (ICI) therapy, including a comparison between those with ICI-induced arthritis and those with ICI-induced arthralgia.

METHODS

Patients with cancer who developed clinical arthritis or arthralgia (ie, joint pain without clinical synovitis) after receiving ICIs were consecutively recruited from six international centres. Patients underwent a full clinical assessment and ultrasound evaluation of 18 joints, 15 tendons and 5 entheses bilaterally, using the Outcome Measures in Rheumatology definitions.

RESULTS

A total of 101 patients were included: 53 (52.5%) had ICI-arthralgia (absent clinical synovitis). Among them, 25 (47.2%) had ultrasound-detected subclinical synovitis, 10 (18.9%) tenosynovitis, 1 (1.9%) digital extensor peritendinitis and 13 (24.5%) enthesitis. In the 48 patients with ICI-arthritis, ultrasound-detected synovitis was more prevalent than in ICI-arthralgia (93.8% vs 47.2%, p<0.001), particularly in the wrists (56.3% vs 20.8%, p<0.001) and the knees (54.2% vs 13.2%, p<0.001), which were the most frequently affected joints. Tenosynovitis (52.1% vs 18.9%, p<0.001), peritendinitis (10.4% vs 1.9%, p=0.099) and bone erosions (25% vs 7.5%, p=0.027) were also more frequent in ICI-arthritis. 'Active' enthesitis was similar between groups (31.3% vs 24.5%), with no significant differences.

CONCLUSIONS

This multicentre study reveals a higher burden of ultrasound-detected changes in ICI-arthritis compared with ICI-arthralgia, with diverse patterns across joints, tendons and entheses in both subtypes. Significant subclinical inflammation suggests that many cases of non-specific ICI-arthralgia may benefit from targeted interventions.