Role of 18F-AlF-NOTATATE PET/CT in selecting pediatric neuroblastoma candidates for 177Lu-DOTATATE peptide receptor radionuclide therapy

Background Neuroblastoma is the most common extracranial solid tumor in children. Peptide receptor radionuclide therapy (PRRT) is a treatment modality with great potential, however, the predictive indicators for its efficacy remain unclear. The aim of the study is to evaluate the prognostic utility of quantitative metrics obtained from 18 F-AlF-NOTATATE PET/CT at baseline and post-treatment for predicting response in PRRT in pediatric neuroblastoma. Methods Patients with high-risk neuroblastoma that was either recurrent or resistant to treatment were prospectively enrolled for one or two cycles of 177 Lu-PRRT. 18 F-AlF-NOTATATE PET/CT was performed 1 month before and after PRRT; some patients underwent mid-treatment scans (7 weeks post-cycle). Treatment response was evaluated using a modified approach combining principles from European Organization for Research and Treatment of Cancer (EORTC) criteria and Response Evaluation Criteria In Solid Tumors (RECIST version 1.1) criteria. Lesions were delineated semiautomatically to obtain maximum standardized uptake value (SUV max ), mean standardized uptake value (SUV mean ), ratio of tumor SUV max to liver SUV max (SUV T/L ), ratio of tumor SUV max to spleen SUV max (SUV T/S ), tumor volume, total lesion activity, and heterogeneity values. Data were analyzed using independent t -tests or Mann–Whitney U tests. Receiver operating characteristic curves were used to determine the optimal cut-offs for PET parameters. Results Twenty-two patients (13 boys, 9 girls) were included. Baseline PET revealed significantly lower SUV T/S , tumor volume, and total lesion activity in non-progressive lesions ( p < 0.05); SUV T/S predicted efficacy (area under the curve [AUC], 0.588). Interim PET showed significantly lower SUV max , SUV mean , SUV T/L , and SUV T/S in non-progressive lesions ( p < 0.05); SUV T/L predicted efficacy (AUC, 0.740). The SUV max ratio (interim/baseline) had the highest predictive accuracy, with a cut-off of 1.25 (AUC, 0.796; sensitivity, 73.03%; specificity, 76.92%). Conclusion Quantitative baseline and mid-treatment 18 F-AlF-NOTATATE PET/CT-derived parameters possess value in predicting PRRT response. An interim-to-baseline PET-derived lesion SUV max ratio of ≤1.25 can effectively predict neuroblastoma response to PRRT.