Background

Immunotherapy can produce atypical response patterns such as pseudoprogression which complicates assessment by size alone. Imaging biomarkers including radiomics PET metrics and functional MRI parameters may provide earlier indicators of response or resistance. Robust validation is required before clinical adoption.

Candidate Biomarkers

PET based metrics of metabolic activity and radiomic texture features from CT or MRI have shown promise in early studies. Dynamic contrast MRI and diffusion metrics may reflect changes in tumor microenvironment and immune infiltration. Combining imaging biomarkers with blood based markers may improve predictive performance.

Clinical Trials and Validation

Prospective trials with standardized imaging protocols are needed to validate biomarkers and define thresholds for clinical decisions. Harmonization across scanners and reconstruction methods is essential for reproducibility. Regulatory qualification pathways should be pursued for biomarkers intended as trial endpoints.

Clinical Integration

Imaging biomarkers can inform early treatment modification and trial stratification when validated and standardized. Implement biomarker reporting with clear interpretation and recommended actions for clinicians. Multidisciplinary tumor boards should incorporate biomarker data into decision making.