262MO - Prognostic significance of deep and rapid prostate-specific antigen (PSA) response with docetaxel (DOC) or abiraterone (ABI): A territory-wide real-world analysis of 574 Asian metastatic hormone-sensitive prostate cancer (mHSPC) patients

Background

The prognostic significance of PSA kinetics after DOC or ABI treatment in Asian mHSPC patients (pts) remains undetermined. We evaluated PSA response to DOC or ABI and its association with survival outcome.

Methods

The medical records of 574 mHSPC pts who received DOC (n = 419) or ABI (n = 155) in addition to androgen-deprivation therapy at seven public oncology centers in Hong Kong between 2015 and 2021 were reviewed. Overall survival (OS) and progression-free survival (PFS) for pts with and without a deep and rapid PSA decline (≥90% decline in PSA level [PSA90] at 3 months [mo] or undetectable PSA nadir (<0.1 ng/mL) were compared. Survival and hazard ratios (HRs) were estimated using the Kaplan-Meier method and Cox proportional hazard model, respectively.

Results

Median follow-up period was 22.4 (DOC: 23.8; ABI: 17.3) mo. A substantially higher proportion of pts achieved PSA90 with ABI than with DOC at 3 (74% vs 26.2%, p < 0.001) mo. Median time to undetectable PSA nadir was 6.2 (interquartile range: 3.6 – 11.5) mo. At 6 mo, an undetectable PSA nadir was observed in 46.0% and 11.9% of ABI and DOC pts, respectively. Pts who achieved PSA90 at 3 mo had better median PFS (entire cohort: 27.1 vs 14.5 months, p < 0.001, HR = 0.47; DOC: 17.7 vs 13.8 mo, p < 0.001, HR = 0.62; ABI: not reached [NR] vs 29.1 mo, p = 0.03, HR = 0.53) and OS (entire cohort: NR vs 58.5 mo, p < 0.001, HR = 0.43; DOC: NR vs 58.5 mo, p < 0.001, HR = 0.38; ABI: NR vs 43.0 mo, p = 0.01, HR = 0.39). Pts who achieved undetectable PSA nadir also had better median PFS (53.6 vs 13.2 mo, p < 0.001, HR = 0.14) and OS (NR vs 48.4 mo, p < 0.001, HR = 0.13). These associations remained significant for the separate treatment groups (PFS: DOC: 42.5 vs 13.4 mo, p < 0.001, HR = 0.21; ABI: NR vs 11.0 mo, p < 0.001, HR = 0.08; OS: DOC: NR vs 58.5 mo, p < 0.001, HR = 0.09; ABI: NR vs 26.1 mo, p < 0.001, HR = 0.08).

Conclusions

Deep and rapid PSA responses with DOC or ABI in Asian mHSPC patients were associated with significantly improved survival outcome, with potentially valuable prognostic significance for patient management and future trial design.

Clinical trial identification

Editorial acknowledgement

Assistance with statistical analysis and language editing were provided by Best Solution Co. Ltd.

Legal entity responsible for the study

The authors.

Funding

Hong Kong Society of Uro-Oncology.

Disclosure

All authors have declared no conflicts of interest.