In rheumatoid arthritis, the incidence of malignancies that are indicated for immune checkpoint inhibitors is increasing.

72 Background: An important side effect of immune checkpoint inhibitors (ICI) is immune related side effects, and in autoimmune diseases, the incidence is increased. For this reason, ICI for autoimmune diseases are carefully administered. However, among the malignancies that develop in autoimmune diseases, the frequency at which the (ICI) is indicated is unclear. This study is to clarify the incidence of malignancies to which ICIs are indicated in rheumatoid arthritis (RA), a typical autoimmune disease. Methods: In RA patients, the development of malignant tumors that can be indicated for IC was investigated at every year from September 2014, (September 2014 - August 2015: 2014 group; September 2015 - August 2016: Group 2015; September 2016 - August 2017: 2016 Group; September 2017 - August 2018: 2017 group). Patients with a history of malignant tumor treatment within 10 years were excluded at registration. IC adaptation was judged by the presence or absence of IC adaptation approval at diagnosis of malignant tumor. Results: The number of RA patients, age (year), disease duration (year), malignant tumor incidence (%), IC adaptive malignant tumor incidence (%) of each group are shown; [n = 479, 68(61-77), 8.8 (4.4-13.9), 9 (1.9%), 0 (0%)], [n = 504, 68 (61-77), 8.0 (3.7-12.8), 12 (2.4%), 0 (0%)], [n = 514, 68(61-77), 7.4 (3.4-12.7), 7 (1.4%), 1 (0.2%)], [n = 526、67 (60-76), 7.3 (3.1-12.6), 37 (7.0%), 9 (1.7%)]. Conclusions: The incidence of IC-adapted malignancy has increased in RA due to an increase in malignant tumor incidence, development of a new IC (methods), combined use of IC and other cancer treatment methods, and expansion of IC indication diseases. Due to the coexistence of autoimmune diseases and malignancy therapy, familiarity with malignant tumor treatment is essential for rheumatologists.