Abstract
To evaluate the accuracy of Response Evaluation Criteria In PSMA-Imaging (RECIP) 1.0 determined by visual reads of nuclear medicine physicians for response evaluation using PSMA-PET/CT in men with mCRPC treated with 177Lu-PSMA radioligand therapy. In total, 124 patients were included in this multicenter retrospective study. All patients received 177Lu-PSMA and underwent PSMA-PET/CT scans at baseline (bPET) and at 12 weeks (iPET). Five nuclear medicine specialists individually interpreted each pair of PSMA-PET/CT scans for responses in PSMA-positive total tumor volume (PSMA-VOL) assessed visually and for occurrence of new lesions. Responses in PSMA-VOL were also assessed quantitatively using semi-automatic segmentation software. Occurrence of new lesions was combined: 1) with visual responses in PSMA-VOL to determine visual RECIP; and 2) with quantitative responses in PSMA-VOL to determine quantitative RECIP. RECIP response classes were dichotomized for differentiation of clinically relevant progressive (PD) vs. non-progressive disease (nPD): RECIP-PD vs. RECIP-nPD. Primary outcome measure was the inter-reader reliability of visual RECIP and agreement between visual vs. quantitative RECIP (by Cohen's κ coefficient). Secondary outcome measure was the prognostic value of visual RECIP (by Cox regression) for overall survival (OS). Based on readers’ majority rule, 41/124 (33%) and 83/124 (67%) patients had visual RECIP-PD and RECIP-nPD, respectively. Agreement among readers in classifying visual RECIP-PD vs. RECIP-nPD was observed in 103 (83%) patients (excellent agreement: κ = 0.81). Agreement between visual vs. quantitative RECIP was observed in 118 (95%) patients (excellent agreement: κ = 0.89). OS was significantly shorter in men with visual RECIP-PD vs. RECIP-nPD (HR 2.55; 95%CI, 1.71–3.81; P < 0.001). The median OS was 8.4 months (95%CI, 7.0–9.8) for patients with RECIP-PD and 16.1 months (95%CI, 13.6–18.5) for patients with RECIP-nPD. Visual RECIP demonstrated excellent inter-reader reliability and excellent agreement with quantitative RECIP calculated using semi-automatic segmentation software. Visual RECIP was prognostic for overall survival of men undergoing 177Lu-PSMA radioligand therapy. RECIP 1.0 evaluated visually by nuclear medicine physicians can be used in practice and clinical trials for response evaluation using PSMA-PET/CT in men with mCRPC.
Published Version
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