Clinical Profile and Outcomes in Anti-TIF1γ Positive Idiopathic Inflammatory Myositis Patients: A Greek Cohort Study.

Background: Anti-transcription intermediary factor 1-gamma (anti-TIF1γ) antibodies are closely associated with Inflammatory myositis (IIM) and cancer-associated myositis.

Objective: Description of clinical characteristics of anti-TIF1γ(+) IIM patients in a Greek population.

Material & methods: Retrospective analysis with 113 IIM cases between 2001 and 2024 was performed and clinical and laboratory data were collected. Disease manifestations and outcomes were compared between anti-TIF1γ-positive and -negative groups.

Results: Twenty patients (17.7%) were anti-TIF1γ(+), of which 70% were women. The mean age was 64.8 ± 12.5 years vs 59.61 ± 12.81 of anti-TIF1γ(-) patients (p>0.05). Anti-TIF1γ was strongly associated with Dermatomyositis (DM) (95%, p < 0.001) and more severe cutaneous involvement (mean CDASI=27.35 ± 15.01 vs 14 ± 12.25 p =0.0015). Malignancy was significantly more frequent in the anti-TIF1γ(+) group (60% vs. 20.4%, p = 0.001), with an odds ratio of 5.84 (95% CI 2.09-16.31). Logistic regression identified anti-TIF1γ positivity as independent predictor of malignancy. Interstitial Lung Disease was uncommon among anti-TIF1γ(+) cases (15%, p = 0.004), while dysphagia was far more prevalent (55% vs. 22.6%, p = 0.001). Muscle power (MMT-8score) and CPK levels did not differ significantly, and survival was lower in anti-TIF1γ(+) patients (55.7% vs. 82.6% p<0.001), associated with malignancy.

Conclusions: In our cohort, anti-TIF1γ antibodies define a distinct IIM subset marked by severe skin disease, high malignancy risk, and poorer survival, supporting comprehensive cancer screening and tailored immunosuppressive treatment. This study describes this phenotype in a Greek cohort, aligning with international evidence and highlighting the need for collaborative studies.