PSMA PET and FDG PET as predictors of response and prognosis in a randomized phase 2 trial of 177Lu-PSMA-617 (LuPSMA) versus cabazitaxel in metastatic, castration-resistant prostate cancer (mCRPC) progressing after docetaxel (TheraP ANZUP 1603).

• DOI: 10.1200/jco.2022.40.6_suppl.010
• Publication Date: 2022-02-16T16:35:25Z
• Authors: James Patrick Buteau; Andrew James Martin; Louise Emmett; Amir Iravani; Shahneen Kaur Sandhu; Anthony M. Joshua; Alison Yan Zhang; Roslyn J. Francis; Andrew Mark Scott; Arun Azad; Margaret Mary McJ...; Martin R. Stockler; Scott Williams; Ian D. Davis; Michael S Hofman
• Keywords: Cabazitaxel; Clinical endpoint

10 Background: The TheraP trial showed that LuPSMA improved PSA≥50% response rate (PSA50-RR), PSA-PFS, and radiographic PFS (rPFS) compared with cabazitaxel in mCRPC progressing after docetaxel. Study inclusion required high PSMA uptake (SUVmax≥20) no lesions were FDG+ PSMA-. Here we report on PET FDG as potential predictive prognostic biomarkers. Methods: We prospectively analysed semi-automated quantitative parameters centrally- collected 68 Ga-PSMA-11 18 F-FDG 200 eligible men. SUVmean ≥10 was evaluated a biomarker for to Lu-PSMA vs cabazitaxel. Metabolic tumor volume (MTV) ≥200mL tested accounting the randomly assigned treatment. Quantitative cut-offs pre-specified from prior research (PMID:32140802). Responses defined according PSA50-RR (primary endpoint), PSA-PFS rPFS. Binary endpoints analyzed using logistic Cox regression, respectively. Results: Very (SUVmean≥10) seen 35/99 (35%) 30/101 (30%) odds of vs. significantly higher men SUVmean≥10 (OR 12.2, 95%CI 3.4-59 2.2, 1.1-4.5; p = 0.03). In SUVmean≥10, 32/35 (91%) 14/30 (47%). < 10, 33/64 (52%) 23/71 (32%). High-volume metabolic disease (MTV ≥200mL) 30/99 these 17/30 (57%) 6/30 (20%) comparison, MTV 200mL 48/69 (70%) 31/71 (44%) After treatment, PSA50-response lower among 0.44; 0.01). HR 0.45 (95%CI 0.25-0.80) 0.77 0.53-1.12) (p 0.2). Findings similar HRs adjusted treatment 1.44 1.03-2.02) 0.03); 1.79 1.28-2.52) rPFS 0.001). Conclusions: mCRPC, likelihood favourable than cabazitaxel, whilst associated worse prognosis regardless Clinical information: NCT03392428.