Background Androgen receptor targeted therapies (ARTs) are widely preferred over taxane chemotherapy due to their good tolerability and similar efficacy. However, there is a paucity of data that supports the use of ART therapy or describes end-of-life (EOL) outcomes in mCRPC patients with reduced PS (PS) (ECOG ≥ 2). Methods We performed a retrospective, single-institution study of 142 patients with mCRPC who received ART therapy between 2010 and 2021. We assessed each record for baseline demographic and clinical information, ART treatment course, and survival and EOL outcomes. Our primary aim was to compare overall survival between the two groups (ECOG > 2 vs. 0-1), and our secondary aim was to describe EOL outcomes. Fisher's Exact Tests and Wilcoxon signed rank tests were used to compare baseline characteristics. Cox regression was used to compare overall survival (OS) for patients with ECOG ≥ 2 at the start of treatment with those who had an ECOG of 0 or 1. Descriptive analyses were performed to assess EOL outcomes between the groups. Results Patients with mCRPC and decreased PS experienced shorter overall survival on ART, compared to those with higher PS. Moreover, when examining EOL outcomes, a near majority of these patients died in the hospital, with a greater percentage among those with an ECOG ≥ 2. Conclusion These findings highlight the need for continual assessment of PS, improved shared decision-making in ART treatment, and additional research exploring the association between PS and EOL outcomes.

117 Background: Prostate cancer (PCa) and especially advanced PCa largely affects older adults with a median age of diagnosis of 67. Despite ART’s role as a mainstay of treatment (tx) in advanced PCa, little is known about its risks/benefits in older adults. We aimed to examine survival outcomes and safety in patients (pts) with mCRPC ≥75 years-old (y.o) on ART. Methods: The records of mCRPC pts treated with ART at the Mount Sinai Hospital between 2010 and 2021 were screened for demographics, medical history, ART course, tx toxicity, and survival outcomes. PSA progression free survival (PFS) between pts ≥75 y.o and pts ≤75 y.o was assessed as the primary outcome. Secondary outcomes were overall survival (os) and tx toxicity. Tx toxicity was evaluated using physician documented tx side-effects (SE)s. Fischer’s exact was used to compare baseline characteristics and tx SEs. Cox proportional hazards models were used to compare survival outcomes. Results: Of 153 pts, 97 were < 75 y.o and 56 were ≥75 y.o. Within the <75 y.o group, 17 (17.5%) were post-chemo compared to 7 (12.5%) in the ≥75 group (p = .493) Relevant baseline characteristics (ECOG ≥2, Race, Gleason 4-5, hospitalizations, and CCI) were not significantly different. Median PSA PFS was 14.2 (≥75 y.o) and 17.3 months (<75 y.o) with no significant difference on univariate or multivariate analysis (HR: 1.1 [0.69, 1.74;] p = 0.697. Median OS was 32.4 months for the ≥75 y.o cohort and 32.3 months for the <75 y.o cohort (HR: 1.38 [0.88, 2.17;] p = 0.156). The 5 most common SEs by group are reported below. Of note, adults ≥75 y.o were more likely to report edema compared to the <75 y.o pts (8.2% vs 21.4%, p-value = .026). Conclusions: Pts ≥75 on ART experienced similar survival benefits compared with pts <75. While older adults were more likely to report edema, overall tx toxicity profiles did not differ significantly. Ultimately, these findings ground evidence-based counseling and tx for older adults with mCRPC considering ART. [Table: see text]

135 Background: mCRPC is associated with (a/w) increased mortality among prostate cancer pts and new and safe txs are needed. In recent clinical trials, ARTs improved survival outcomes within this population, however, a significant portion will go on to discontinue tx. We aim to describe reasons for ART tx discontinuation and to identify predictors a/w increased risk of tx discontinuation due to tx toxicity or death. Methods: We performed a single-institution retrospective review of mCRPC pts on ART between 2010 and 2021. We screened for demographics, medical history, ART course, and tx side-effects. Our primary aim was to identify risk factors for tx discontinuation due to toxicity or death. Our secondary aim was to describe ART discontinuation among mCRPC. Fisher’s Exact was used to identify significant predictors of tx discontinuation due to toxicity or death. Significant outcomes were included in a multivariate logistic regression to determine odds ratios. Results: 133 pts with mCRPC started and discontinued ARTs. Among this cohort, 27 pts (20.3%) discontinued tx due to death or toxicity. Reasons for tx discontinuation are described in the table below. Significant predictors of tx discontinuation due to toxicity or death on bivariate analysis included pt-reported sepsis, hypertension (htn), weakness, falls, ECOG ≥2, and hospitalization during tx. Adjusting for confounders, pt-reported falls (OR 2.35; [0.91-2.59]; p=0.009), htn (OR 2.06; [0.94-2.21]; p=0.027), and weakness (OR 1.63; [0.59-2.72]; p=0.007) were a/w an increased risk of pt tx discontinuation from toxicity or death. Conclusions: Our results illustrate that the majority of mCRPC pts discontinued tx due to progression of disease. The data also indicates that mCRPC pts reporting new onset htn, falls, or weakness were more likely to discontinue tx due to toxicity or death. Early monitoring of this population is warranted to prolong duration of tx and prevent unnecessary txs. [Table: see text]

118 Background: mCRPC pts with significant comorbidities or poor performance status (PS) are often excluded from clinical trials for ART. These cohorts may not be representative of or comparable to real-world pts. We aimed to determine whether (1) baseline characteristics or (2) survival outcomes differed in pts with mCRPC categorized as eligible or ineligible for ART clinical trials. Methods: We screened for pts with mCRPC treated with abiraterone (abi-) or enzalutamide (enza-) at our institution between 2010 and 2021. Baseline characteristics were reviewed at treatment start and ART course recorded. We applied the inclusion/exclusion criteria from clinical trials, COU-AA-301, COU-AA-302, PREVAIL, and AFFIRM, to categorize pts as ineligible or eligible. Fischer’s exact was used to evaluate pt characteristics. Cox proportional hazards model was used to compare survival outcomes. Results: We identified 150 pts with mCRPC who initiated abi- or enza-. 54.7% of pts were deemed trial ineligible. Among pts on abi-, 48 of 86 (55.8%) pts were ineligible. Among those on enza-, 34 of 64 (53.1%) were ineligible. Common reasons for ineligibility included poor PS, radiation during treatment, and trial specific comorbidities. Among ineligible pts, 11% were post-chemotherapy compared to 20.6% of eligible pts (p = .162). Notably, trial ineligible pts were more likely to be non-Hispanic black when compared to trial eligible pts (29.3% vs. 17.6%, p = 0.036). Median OS was 30.2 for ineligible pts and 37.1 for eligible pts p = 0.46). for the ineligible pts and eligible pts respectively and there was no significant difference on univariate or multivariate analyses (HR: 0.84 [0.54, 1.32;]. Conclusions: Pts classified as trial ineligible had comparable survival outcomes when compared to trial eligible pts. Consistent with prior research on systemic racism in clinical trials, ineligible pts were more likely to identify as Black compared to eligible pts. Further research is warranted to confirm safety of ART in ineligible pts and identify strategies for reducing racial disparity gaps in cancer clinical trials.

194 Background: Statins may reinforce and provide a compounded effect on ART by decreasing cholesterol levels thus decreasing de novo androgen synthesis. We aim to investigate the clinical effect of concurrent statin and ART use on outcomes of mCRPC patients. Methods: We conducted a retrospective analysis on mCRPC patients receiving ART from a single institution. Relevant demographic and clinical data was collected in addition to ART treatment course, statin treatment, and survival outcomes. Our primary outcome was PSA progression free survival (PFS) and our secondary outcomes were overall survival (OS) and associated prognostic factors for both PSA PFS and OS. Chi-squared test and Wilcoxon signed ranked test were used to compare baseline characteristics, and a Cox proportional hazards regression model was used to estimate hazard ratios (HR) with 95% confidence interval (CI) for overall survival (OS) and PSA PFS. Results: 153 patients were included in the analysis between 2010 and 2021. 67 patients (mean age 73.8 years) received concurrent statins and 86 patients (mean age 67.6 years) did not. Median PSA PFS was 37.4 months for patients that received concurrent statins and 17.4 months for patients that did not receive statins. On univariate and multivariate analyses, there was no statistically significance difference between groups for PSA PFS (HR 0.7; CI 0.44-1.1; p=0.122). Median OS was 35.6 months for patients that received concurrent statins and 24.0 months for patients who did not. There was no statistical significance between groups for OS on univariate or multivariate analyses (HR 0.67; CI 0.42-1.06; p=0.087). Conclusions: Although results were not statistically significant, our study illustrates that concurrent statin use exhibits improved time to PSA progression and OS in mCRPC patients. Larger multi-center and further prospective studies are warranted to elucidate the relationship between statin use and overall outcomes in this population.