Novel Framework for Treatment Response Evaluation Using PSMA PET/CT in Patients with Metastatic Castration-Resistant Prostate Cancer (RECIP 1.0): An International Multicenter Study.

Abstract

Our objective was to develop version 1.0 of a novel framework for response evaluation criteria in prostate-specific membrane antigen (PSMA) PET/CT (RECIP) and a composite response classification that combines responses by prostate-specific antigen (PSA) measurements and by RECIP 1.0 (PSA + RECIP). Methods: This was an international multicenter, retrospective study. One hundred twenty-four men with metastatic castration-specific prostate cancer (mCRPC) who underwent 177Lu-PSMA therapy and received PSMA PET/CT at baseline and at an interim time point of 12 wk were included. Pairs of baseline interim PET/CT scans were interpreted by consensus among 3 masked readers for appearance of new lesions. Tumor lesions were segmented, and total PSMA-positive tumor volume (PSMA-VOL) was obtained. Appearance of new lesions and changes in PSMA-VOL were combined to develop RECIP 1.0, which included classifications of complete response (RECIP-CR: absence of any PSMA-ligand uptake on interim PET/CT), partial response (RECIP-PR: decline ≥ 30% in PSMA-VOL and no appearance of new lesions), progressive disease (RECIP-PD: increase ≥ 20% in PSMA-VOL and appearance of new lesions), and stable disease (RECIP-SD: any condition but RECIP-PR or RECIP-PD). Changes in PSA levels at 12 wk by Prostate Cancer Working Group Criteria 3 were recorded. PSA + RECIP results were defined as response (PSA decline ≥ 50% or RECIP-PR/CR) or progression (PSA increase ≥ 25% or RECIP-PD). The study's primary outcome measure was the prognostic value of RECIP 1.0 for overall survival (OS). The secondary outcome measure was the prognostic accuracy (C-index) of PSA + RECIP versus PSA responses. Results: Patients with RECIP-PD (n = 39; 8.3 mo) had a shorter OS than patients with stable disease (RECIP-SD) (n = 47; 13.1 mo; P < 0.001) or RECIP-PR (n = 38; 21.7 mo; P < 0.001). In identifying responders and progressors, PSA + RECIP had C-indices superior to those of PSA only: 0.65 versus 0.62 (P = 0.028) and 0.66 versus 0.63 (P = 0.044), respectively. Conclusion: PSMA PET/CT by RECIP 1.0 is prognostic for OS and can be used as a response biomarker to monitor early efficacy of 177Lu-PSMA in men with mCRPC. PSA + RECIP may be used as a novel composite endpoint in mCRPC clinical trial design.

• Authors: Andrei Gafita, Isabel Rauscher, Manuel Weber, Boris Hadaschik, Hui Wang, Wesley R Armstrong, Robert Tauber, Tristan R Grogan, Johannes Czernin, Matthew B Rettig, Ken Herrmann, Jeremie Calais, Wolfgang A Weber, Matthias R Benz, Wolfgang P Fendler, Matthias Eiber
• Journal: Journal of nuclear medicine : official publication, Society of Nuclear Medicine (J Nucl Med) Vol. 63 Issue 11 Pg. 1651-1658 (11 2022) ISSN: 1535-5667 [Electronic] United States
• PMID: 35422442 (Publication Type: Multicenter Study, Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2022 by the Society of Nuclear Medicine and Molecular Imaging.

Chemical References

• Prostate-Specific Antigen
• Heterocyclic Compounds, 1-Ring
• Lutetium
• Radiopharmaceuticals
• Dipeptides

Topics

• Male
• Humans
• Positron Emission Tomography Computed Tomography
• Prostatic Neoplasms, Castration-Resistant (pathology)
• Prostate-Specific Antigen
• Heterocyclic Compounds, 1-Ring (therapeutic use)
• Lutetium (therapeutic use)
• Retrospective Studies
• Radiopharmaceuticals (therapeutic use)
• Dipeptides (therapeutic use)
• Treatment Outcome