e14580 Background: The use of immune-checkpoint inhibitors (ICIs) for solid malignancies is rapidly rising, and many new agents and treatment combinations are in development. However, ICIs have a unique side-effect profile of immune-related adverse events (irAEs) compared with chemotherapeutic agents or targeted therapies. The aim of this work was to describe the irAEs in diverse types of malignant tumors using real-world data. Methods: This is a retrospective and descriptive study of patients with diverse types of advanced malignancies treated with immunotherapy at Centro Oncológico Integral of the Hospital Ángeles in Puebla, México; during the period 2016-2020. Data about the primary neoplasm, ICIs, irAEs, organ system affected, grade and treatment was collected. Clinical and laboratory parameters were obtained by reviewing medical records. Results: A total of 117 patients were included, median age of 65 years, of which 63.2% were male and 36.8% were female. The most frequent neoplasms treated with ICIs were: lung (27.4%), kidney (16.2%), melanoma (12.8%), hepatocellular (9.4%), breast (8.5%), non-melanoma skin cancer (6.0%), mesothelioma (4.3%) and other tumors (15.3%). 39.3% of the patients had no metastases, 41.9% had metastases to at least 1 or 2 sites, and 18.8% to 3 or more sites. The types of ICIs were: nivolumab (35.0%), pembrolizumab (28.2%), atezolizumab (23.9%), ipilimumab + nivolumab (12.0%) and durvalumab (0.9%). The most frequent irAEs were: gastrointestinal (61.5%), neurologic (46.2%), pulmonary (38.5%), metabolic (32.5%) and hematologic (29.1%). 39.3% of the irAEs were reported as grade 1, 31.6% as grade 2, 14.5% as grade 3 and 2.6% as grade 4. Conclusions: Our work shows the incidence of irAEs in a poorly studied population and provides new data that complement that reported by other works, however, further prospective studies are necessary.[Table: see text]