Pharmacokinetic Study of Therapeutic Plasma Exchange

Inclusion Criteria: * Adults ≥ 18 years of age * Diagnosis of any malignancy. * Receiving or recently received an immune checkpoint inhibitor, including anti-PD-1, anti-PD-L1, anti-CTLA-4, or combination ICI therapy. Eligible agents may include, but are not limited to, pembrolizumab, nivolumab, atezolizumab, durvalumab, avelumab, cemiplimab, dostarlimab, and ipilimumab. * Received an ICI within 12 weeks prior to planned enrollment, or within a timeframe considered appropriate by the PI for PK evaluation based on the specific ICI agent, dosing history, and assay feasibility. * Suspected or confirmed severe or clinically significant immune-related adverse event for which the treating clinical team considers TPE/PLEX clinically appropriate. * Planned to undergo or currently undergoing TPE/PLEX at the University of Chicago Medicine. * Approval from the patient's primary clinical service for study participation. * Able to provide written informed consent, or has a legally authorized representative able to provide consent if permitted by the IRB-approved consent process. * In the opinion of the treating team and study team, PK blood sample collection can be performed without delaying or interfering with clinically indicated care. Exclusion Criteria: * No prior exposure to an immune checkpoint inhibitor. * TPE/PLEX is being performed for an indication unrelated to a suspected or confirmed ICI-associated immune-related adverse event. * Inability to provide informed consent and no …