Immune checkpoint inhibitors (ICIs) have transformed the treatment of solid tumors but are associated with immune-related adverse events (irAEs) that can affect virtually any organ system. While many irAEs are well recognized, neurological, neurocognitive, and psychiatric toxicities remain diagnostically challenging, potentially severe, and poorly understood, with limited predictive biomarkers.

This prospective longitudinal observational cohort study enrolls adult patients with solid tumors initiating a new course of ICI therapy. Participants undergo standardized baseline clinical assessments and biospecimen collection prior to ICI initiation, followed by longitudinal follow-up and event-driven sampling. Patients are dynamically assigned to organ-specific irAE cohorts based on the first clinically significant irAE that dictates management. Patients without grade ≥2 irAEs during follow-up serve as a comparator control cohort.

The primary objective is to characterize longitudinal immune and inflammatory biomarker trajectories associated with the development of irAEs and to identify predictive and prognostic biomarkers, with particular emphasis on neurological, neurocognitive, and psychiatric toxicities. Integrated clinical, imaging, and multi-omics data will be used to elucidate mechanisms of toxicity and inform future risk stratification and personalized management strategies.

Immune checkpoint inhibitors targeting CTLA-4, PD-1, and PD-L1 pathways have demonstrated substantial clinical benefit across multiple solid malignancies. However, their mechanism of action can also lead to immune-related adverse events (irAEs), which may involve dermatologic, gastrointestinal, hepatic, pulmonary, endocrine, musculoskeletal, cardiovascular, renal, hematologic, neurological, and psychiatric systems. Neurological and neurocognitive irAEs, in particular, are uncommon but potentially devastating and remain poorly characterized.

This study is a hybrid prospective longitudinal observational cohort designed to move beyond reactive identification of irAEs toward proactive prediction and mechanistic understanding. Adult patients with solid tumors initiating a new ICI regimen are enrolled prior to treatment initiation. Longitudinal clinical data, imaging, and biospecimens are collected at predefined intervals and at the time of suspected irAE onset when feasible.

Participants are assigned to event-defined cohorts based on the first grade ≥2 irAE that drives clinical management, including neuro-sensory, gastrointestinal/hepatic, rheumatologic/musculoskeletal, vascular/renal, hematologic, multi-organ, or control (no significant irAE) cohorts. Deep phenotyping and multi-omics analyses-including immune cell profiling, proteomics, metabolomics, and microbiome analyses-are performed to identify biomarkers associated with irAE risk, severity, and outcomes.

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

Adult patients (≥18 years) with histologically confirmed solid malignancies who are initiating a new immune checkpoint inhibitor regimen, either as standard of care or within an approved clinical trial. Participants are enrolled prior to the first immune checkpoint inhibitor dose and followed longitudinally to assess the development of immune-related adverse events and associated immune and inflammatory biomarker changes.

1. Baseline Characteristics & Demographics: Age, sex, race/ethnicity, baseline body weight and height, diagnosis, treatment history, relevant comorbidities, smoking/alcohol status.
2. Exposure/Treatment Data: Specific checkpoint inhibitor(s) received, dosing regimen, treatment start and end dates, medications.
3. Laboratory & Diagnostic Data: Serial laboratory test results, key imaging findings relevant to irAEs, pathology reports.
4. Outcomes: CTCAE grades, date to primary outcomes, management strategies.
5. Oncologic Outcomes: Tumor response assessments.
6. Supporting Documents for Data Interpretation.

2026.3 to 2029.1

The de-identified IPD and supporting documents will be made available to qualified researchers worldwide upon request. Researchers will have access to the fully de-identified individual participant data listed in the previous section, along with the supporting documents including: the final study protocol, statistical analysis plan, the annotated case report forms. The data dictionary.

All data will be anonymized in accordance with the HIPAA Safe Harbor method. Interested researchers must submit a formal research proposal outlining their study objectives, analysis plan, and ethical considerations via email for review by our Data Access Committee. Requestors will be required to sign a Data Use Agreement that legally binds them to use the data only for the approved purpose, maintain data security, and prevent re-identification or redistribution. Data will then be securely transferred via encrypted file sharing or made available through a controlled-access repository