Can fitness predict how well immunotherapy works? new study aims to find out

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Age ≥18 years * Histologically confirmed solid malignancy * Receiving immune checkpoint inhibitors in one of the following settings: * Adjuvant: Single-agent anti-PD-1, anti-PD-L1, or anti-CTLA-4 * Metastatic/Palliative: Single-agent or dual-agent anti-PD-1, anti-PD-L1, or anti-CTLA-4 * ECOG Performance Status 0-2 * Able to perform cardiopulmonary exercise testing * Able to provide written informed consent * Willing and able to comply with study procedures and follow-up schedule Exclusion Criteria: * Age \<18 years * Prior systemic anti-cancer immunotherapy for unresectable or metastatic disease, EXCEPT: * Prior adjuvant or neoadjuvant immunotherapy if all treatment-related adverse events have returned to baseline or stabilized * Prior anti-PD-1, anti-PD-L1, or anti-CTLA-4 therapy with at least 6 months since last dose and date of disease recurrence * Absolute contraindications to cardiopulmonary exercise testing: * Acute myocardial infarction within 6 weeks * Unstable angina * Uncontrolled cardiac arrhythmias causing symptoms or hemodynamic compromise * Active endocarditis * Symptomatic severe aortic stenosis * Uncontrolled heart failure * Acute pulmonary embolism or pulmonary infarction * Acute myocarditis or pericarditis * Suspected or known dissecting aneurysm * Acute systemic infection * Inability to perform cardiopulmonary exercise testing (e.g., severe lower limb dysfunction, severe peripheral vascular disease) * Inability to provide informed consent * Currently enrolled in another interventional clinical trial that would confound study outcomes ADDITIONAL EXCLUSION CRITERIA FOR RESEARCH BIOPSY SUB-STUDY: * Severe cardiopulmonary disease precluding safe sedation (for endoscopic biopsies) * Suspected bowel obstruction or perforation (for gastrointestinal biopsies) * Uncorrectable severe coagulopathy (INR \>1.5, platelet count \<50,000/µL) * Severe portal hypertension with high-risk varices (for upper endoscopy) * Lesion inaccessible for safe biopsy as determined by a performing clinician