Post-ARPI sequencing in mCRPC: A propensity-matched real-world comparison of ¹⁷⁷ Lu-PSMA-617 versus docetaxel for early clinical outcomes.

5079 Background: Treatment sequencing in metastatic castration-resistant prostate cancer (mCRPC) after ADT and ARPI exposure varies in practice. While 177 Lu-PSMA use is expanding in routine practice, real world head to head comparisons with docetaxel in ARPI-exposed mCRPC are limited, particularly for short-term outcomes and treatment related acute care utilization. Methods: Using TriNetX, adults > 18 years of age with metastatic prostate cancer and prior ARPI exposure who initiated 177 Lu-PSMA or docetaxel were identified (index = first administration). Cohorts were balanced with 1:1 propensity score matching (PSM) on demographics and baseline comorbidities. Outcomes from day 1–180 post-index included all-cause mortality (primary), hospitalization, acute kidney injury (AKI; ICD-10 N17), and thromboembolic/ischemic events (ICD-10 I21/I26/I63/I82). For each outcome, patients with prior documentation of that outcome were excluded. Outcomes are reported as risks and risk ratios (RR) with 95% confidence intervals. Results: Before matching, 563 patients initiated 177 Lu-PSMA-617 and 8,749 initiated docetaxel; after 1:1 PSM, 497 patients per cohort were analyzed. At 180 days, all-cause mortality was 7.3% (36/494) with 177 Lu-PSMA-617 versus 12.2% (60/491) with docetaxel (RR 0.60, 95% CI 0.40–0.88). Hospitalization occurred in 7.2% (21/290) versus 21.1% (52/247) (RR 0.34, 95% CI 0.21–0.55). In a separate matched renal-safety analysis (480 per cohort), AKI occurred in 2.8% (11/390) versus 9.0% (36/399) (RR 0.31, 95% CI 0.16–0.60). Thromboembolic/ischemic events were 3.8% (15/394) versus 6.4% (26/404) (RR 0.59, 95% CI 0.32–1.10). Conclusions: In ARPI-exposed mCRPC, 177 Lu-PSMA was associated with lower 180-day mortality risk and substantially fewer hospitalizations than docetaxel, with a lower risk of AKI. These findings highlight a potential short-term effectiveness and acute-care utilization advantage of 177 Lu-PSMA in routine practice and support further prospective evaluation. Key 180-day outcomes after matching. Outcome 177 Lu-PSMA Docetaxel Effect estimate (180 days) All-cause mortality 36/494 (7.3%) 60/491 (12.2%) RR 0.596 (0.402-0.884) Hospitalization 21/290 (7.2%) 52/247 (21.1%) RR 0.344 (0.213-0.554); Acute kidney injury (AKI)* 11/390 (2.8%) 36/399 (9.0%) RR 0.312 (0.163-0.595) Thromboembolic/ischemic† 15/394 (3.8%) 26/404 (6.4%) RR 0.592 (0.318-1.100) *AKI analysis used a separate matched run (480 per cohort). †Composite of I21, I26, I63, I82.