A recent imaging study found that patients who develop joint pain after receiving immune checkpoint inhibitors (ICIs) for cancer often show signs of inflammation and joint damage on whole-body magnetic resonance imaging (MRI), even in the absence of joint swelling or clinical signs of arthritis.
The findings suggest that musculoskeletal side effects of these therapies may be more common and underrecognized than previously reported.
Investigators examined 60 adults who developed new musculoskeletal symptoms during or within six months of initiating ICI treatment. All underwent contrast-enhanced whole-body MRI and were compared with 20 healthy control participants. Patients were classified as having either arthralgia (joint pain without swelling) or inflammatory arthritis (pain with swelling or stiffness).
Both patient groups had significantly more inflammation and joint erosions on MRI compared with healthy controls. Median synovitis scores were 9 in the arthralgia group and 10 in the inflammatory arthritis group, compared with 2 in controls. Erosion scores were also elevated in both patient groups, with a median score of 2 versus 0 in controls
Three distinct inflammatory patterns were identified: peripheral inflammatory arthritis, polymyalgia rheumatica, and a mixed pattern combining features of both. The most common was peripheral inflammatory arthritis, found in 37% of patients. This group had the highest frequency of treatment with glucocorticoids and disease-modifying antirheumatic drugs (DMARDs); four of five patients who required DMARDs were in this group.
The mixed-pattern group, comprising 20% of patients, exhibited signs of both peripheral arthritis and polymyalgia rheumatica, an inflammatory condition affecting the shoulders and hips. These patients had the most rapid symptom onset and were more likely to be older and on combination ICI therapy.
One patient demonstrated a spondyloarthropathy pattern, which affects the spine. Nineteen patients did not meet criteria for a specific pattern but showed evidence of inflammation that may evolve over time. Four additional patients had myofascial inflammation involving muscles and surrounding connective tissue.
Notably, patients with arthralgia had nearly the same level of MRI-detected inflammation and erosions as those with clinical arthritis, despite the absence of joint swelling. This suggests physical examination alone may not be sufficient to evaluate joint toxicity in patients undergoing ICI therapy.
The study population had a mean age of 65 and included individuals treated for melanoma, lung, renal, and other cancers. Most were receiving anti–PD-1 or anti–PD-L1 monotherapy, while 30% were on combination therapy with CTLA-4 inhibitors.
The results indicate that rheumatologic complications from ICIs may be underdiagnosed, particularly in patients presenting only with joint pain. The authors suggest that clinicians may need to consider imaging to fully assess musculoskeletal symptoms during or following ICI therapy.
Full disclosures can be found in the study.
Source: The Lancet Rheumatology
