Longitudinal Cohort Study of Immune-Related Adverse Events in Solid Tumor Patients Treated With Immune Checkpoint Inhibitors

Inclusion Criteria: * Age ≥18 years * Histologically confirmed solid malignancy * Planned initiation of a new immune checkpoint inhibitor regimen (monotherapy or combination) as standard of care or on an approved clinical trial * Ability to provide informed consent * Baseline study assessments and biospecimen collection completed prior to first ICI dose * Life expectancy of at least 6 months as determined by treating oncologist * Availability of archival tumor tissue or willingness to undergo biopsy if archival tissue is unavailable Exclusion Criteria: * Uncontrolled medical, psychiatric, or social conditions that would interfere with study participation or data interpretation * Chronic systemic immunosuppression exceeding 10 mg/day prednisone equivalent within 14 days prior to enrollment (excluding inhaled, topical, or physiologic replacement doses) * Prior solid organ transplantation or allogeneic hematopoietic stem cell transplantation * Untreated, symptomatic, or progressing brain metastases (treated and stable brain metastases allowed if off systemic steroids for at least 7 days) * Inability or unwillingness to provide required baseline biospecimens