SAT0271 RELATIONSHIP BETWEEN ANTI-MDA5 ANTIBODIES AND CANCER: RETROSPECTIVE ANALYSIS OF AN INTERNATIONAL AND MULTIDISCIPLINARY COHORT

Abstract

Background: Myositis specific antibodies play a central role in the assessment of idiopathic inflammatory myopathies (IIMs) as their presence may indicate specific disease subsets/manifestations or cancer risk. At present, anti-MDA5 antibodies have been associated with the occurrence of rapidly progressive interstitial lung disease (RP-ILD), a life-threatening condition, generally refractory to treatment. Objectives: To describe the relationship between malignancy and anti-MDA5 antibodies in IIMs. Methods: Patients with anti-MDA5+ IIMs and a history of cancer were included in this study. Data were retrospectively collected. Because of the lack of RP-ILD shared definitions, we defined RP-ILD as an admission to the Intensive Care Unit (ICU) for IIMs related respiratory insufficiency. Results: In our cohort (n=133, 67% females) we identified 17 patients (13%) with a history of cancer (8 males [47%], 9 females [53%]; median age at IIMs onset 62 years [IQR 53-67], at cancer diagnosis 56 years [IQR 51-66]). All but 1 patient had solid tumours, 5 (29%) had breast cancer. In 9 patients (53%) cancer diagnosis ranged ± 3 years from IIMs onset; in 3 patients the delay exceeded 120 months. Three patients (18%) developed RP-ILD respectively 82, 66 and 0 months after the diagnosis of cancer. Four (24%) patients died respectively 0 (neoplasia), 0 (RP-ILD in ICU, diagnosis of cancer after an autopsy), 7 (neoplasia) and 66 (infection after RP-ILD in ICU) months after cancer diagnosis. The 13 surviving patients had a median rheumatological follow-up of 47 months (IQR 19-84) and an oncological follow-up of 57 months (IQR 10-130). Interestingly, in the overall cohort 66% of patients without cancer (76 out of 116) had less than 3 years of follow-up. Of the 22 RP-ILD patients without neoplasia 14 died, 11 during ICU admission. In the latter patients, we could not rule out an occult neoplasia due to the emergency of the situation. Only one patient, with a 18 month history of IIMs before ICU admission, underwent autopsy and was reported negative for cancer. Conclusion: This is the first study addressed to tackle the relationship between cancer and anti-MDA5+ IIMs. Although in some cases no clear relationship between IIMs and cancer can be proved because of the time gap, in others the timing of occurrence of cancer and IIMs was very close, suggesting a link between these manifestations. Finally, we emphasize the importance of an accurate neoplasm screening in anti-MDA5+ RP-ILD, because treatment refractoriness could suggest the paraneoplastic nature of the manifestation.