PSA response to Lu177-PSMA-617 in patients experiencing xerostomia and ocular dryness in metastatic castration resistant prostate cancer.

127 Background: Lu177-PSMA-617 (PSMA Lu177) therapy can cause dry mouth and/or eyes, as prostate specific membrane antigen (PSMA) is expressed in salivary and lacrimal glands. We evaluate the PSA response in pts with metastatic castration resistant prostate cancer (mCRPC) receiving PSMA-Lu177 who experienced dry mouth/eyes. Methods: The Indiana University Prostate Cancer database was queried for pts with mCRPC who were treated with PSMA Lu177. Adverse Events were documented throughout the course of treatment. PSA30 and PSA50 response were analyzed among subgroups of patients who had presence/absence of xerostomia and ocular dryness. Comparisons between the groups were based on the Chi Square test, or Fisher’s Exact test, if more appropriate. Results: 144 pts with mCRPC were treated with PSMA Lu177 between November 2022 and October 2024. Included pts received at least 2 doses. Median age was 74 (53, 91). 126 pts had metastatic disease in bone, 80 in pelvic lymph nodes, 27 lungs, 20 liver, and 5 brain. 58 pts had 1 prior ARPI, 86 pts had ≥2 prior ARPI. 28 pts had no prior taxane regimen, 116 had at least 1 prior taxane. 23 pts had prior PARP inhibitor. Median follow-up from start of PSMA Lu177 was 9.77 months (1.38-26.9). 62 (43.1%) pts experienced dry mouth, 15 (10.4%) experienced dry eyes, and 13 (9%) experienced both. 92 (63.9%) pts achieved PSA30 response, and 81 (56.3%) achieved PSA 50 response. Conclusions: Patients with mCRPC treated with PSMA Lu177 who reported dry mouth were more likely to experience PSA responses. Number and % of Pts Achieving PSA30 and PSA50 Response Characteristic (N) PSA30 response, N (%) PSA30 p-value PSA50 response, N (%) PSA50 p-value Dry mouth Present (N=62) Absent (N=82) 49 (79%)43 (52.4%) 0.0010 41 (66.1%)40 (48.8%) 0.0377 Dry eyes Present (N=15) Absent (N=129) 11 (73.3%)81 (62.8%) 0.4211 8 (53.3%)73 (56.6%) 0.8099 Dry eyes and/or dry mouth Present (N=64) Absent (N=80) 51 (79.7%)41 (51.3%) 0.0004 43 (67.2%)38 (47.5%) 0.0180