Clinical characteristics and cancer risk of anti-OJ antisynthetase syndrome: A cohort comparative study and a systematic literature review.

[BACKGROUND] Antisynthetase syndrome (ASyS) is a systemic autoimmune disease that primarily affects the lungs, joints, and muscles, and is associated in over 90% of cases with anti-Jo-1, anti-PL7, or anti-PL12 antibodies. ASyS is not associated with malignancy. Anti-OJ autoantibody-positive ASyS is poorly characterized, as it is a rare anti-synthetase antibody and commercial immunoassay kits lack reliability.

[METHODS] We conducted a retrospective comparative cohort study of anti-OJ patients. Anti-OJ was identified by immunoprecipitation. Clinical, biological, radiological, and myopathological data were collected. ASyS OJ-negative patients positive for anti-Jo-1, anti-PL7, or anti-PL12 antibodies were used as controls. Cancer incidences were compared to the aged and sex matched general population using standardized incidence ratios. A systematic literature review of anti-OJ patients was also conducted for descriptive comparison.

[RESULTS] Anti-OJ patients (n = 22) were older at diagnosis (69 years [51.5-75], p < 0.01) and exhibited lower frequencies of muscular (54.5%, p < 0.01) and articular involvement (26.7%, p < 0.01) compared OJ-negative ASyS patients (n = 158), while interstitial lung disease remained a prominent feature in both groups. Cancer incidence was markedly increased in the anti-OJ patients (SIR = 3.23 [95% CI: 1.21-8.62]) compared to general population, in contrast to anti-Jo-1 and anti-PL7/12 patients, where no significant difference was observed. The literature review of anti-OJ patients (n = 106) showed consistent results with our cohort.

[CONCLUSION] Anti-OJ ASyS define a distinct clinical subset within the ASyS spectrum, and a unique increased risk of malignancy. These findings advocate for enhanced malignancy screening and dedicate serological testing in this rare subgroup.