Compatibility of different PET/CT criteria in evaluating treatment response and survival in non-small cell lung cancer patients treated with immunotherapy.

BACKGROUND

Several PET/CT-based criteria have been developed to assess immunotherapy (IT) response, but their correlation with overall survival (OS) and mutual concordance in non-small-cell lung cancer (NSCLC) remains unclear.

METHODS

Pre-treatment and first post-treatment 18F-FDG PET/CT scans of 35 metastatic NSCLC patients receiving second-line or later IT were analyzed using four criteria: PERCIST, PECRIT, PERCIMT, and imPERCIST5. According to each criterion, treatment response was classified as complete metabolic response (CMR), partial metabolic response (PMR), stable metabolic disease (SMD), or progressive metabolic disease (PMD). The primary endpoint was the association with OS, and the secondary was inter-criteria concordance. Patients were stratified by objective response rate (responders: CMR + PMR vs. non-responders: SMD + PMD) and disease control rate (disease control: CMR + PMR + SMD vs. no disease control: PMD).

RESULTS

The mean age was 65 ± 6 years, with 94.3% male patients. Three received pembrolizumab and 32 nivolumab. Median OS after immunotherapy was 12 months (95% CI 8.9-15.1). Responders showed significantly better OS across all four PET/CT criteria. Disease control by PERCIST (HR 0.27, 95% CI 0.10-0.70, p = 0.007) and PERCIMT (HR 0.38, 95% CI 0.16-0.88, p = 0.023) was significantly associated with improved OS, unlike PECRIT and imPERCIST5. Overall concordance among the criteria was good (Fleiss' kappa: 0.70). Concordance was excellent for ORR evaluation (kappa: 0.92), but lower for DCR (kappa: 0.62).

CONCLUSION

In this retrospective exploratory study, PERCIST and PERCIMT demonstrated a stronger association with OS compared with PECRIT and imPERCIST5 when disease control was considered. While agreement across criteria was high for objective response assessment, concordance for disease control was lower.