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Aim: To assess reduction in prostate-specific antigen (PSA) levels among Black and non-Black patients treated with apalutamide for non-metastatic castration-resistant prostate cancer (nmCRPC) or metastatic castration-sensitive prostate cancer (mCSPC). Patients & methods: Patients were identified from electronic medical data. PSA reduction (≥50%, ≥90% or below 0.2 ng/ml) after apalutamide initiation was assessed. Results: A total of 313 patients with nmCRPC and 260 patients with mCSPC were identified. The majority of patients treated with apalutamide achieved a 90% reduction in PSA regardless of indication or race. The proportion of patients achieving a PSA reduction at any level was similar among Black and non-Black patients and was consistent with apalutamide phase III trials. Conclusion: In routine clinical practice, apalutamide consistently produced reduction in PSA levels in Black and non-Black men with nmCRPC or mCSPC.

330 Background: Patients (pts) with localized prostate cancer (LPC) or locally advanced prostate cancer (PC) have several treatment options, including external beam radiation therapy (EBRT) and radical prostatectomy, which can be curative in some pts. However, limited real-world evidence exists on the long-term clinical outcomes of these pts, particularly those with high-risk LPC (HRLPC). This study examines real-world clinical outcomes for HRLPC and low/intermediate risk LPC (LIRLPC) pts treated with EBRT in the US. Methods: A retrospective study using Surveillance, Epidemiology, and End Results (SEER)-Medicare linked registry-claims data from 2012−2019 included LPC pts aged ≥65 treated with EBRT as initial definitive therapy. Baseline demographic and clinical characteristics were summarized for HRLPC and LIRLPC pts. Clinical outcomes of interest (overall survival, metastasis-free survival [MFS] and time to initiation of advanced PC treatment) were compared using Kaplan-Meier (KM) and Cox proportional hazards (PH) models. Results: Of 11,127 LPC pts treated with EBRT within 6 months of LPC diagnosis, ~40% (n=4,414) were HRLPC and ~60% (N=6,713) were LIRLPC. Patient characteristics for both groups appeared similar, with mean age at EBRT initiation >70 years, 86% white, and mean follow-up time >40 months. ADT was used with EBRT in 78% HRLPC and 34% LIRLPC. Median (IQR) duration of ADT therapy (via KM analysis) was 9.9 (5.8, 21.5) months for HRLPC and 7.2 (5.3, 9.8) months for LIRLPC. A higher proportion of HRLPC vs LIRLPC pts experienced metastasis, death, and progression to advanced PC therapies (medians were not reached). Unadjusted Cox PH survival analyses showed higher risk of mortality, metastasis, and advanced PC therapy use for HRLPC vs LIRLPC pts. Conclusions: This real-world study of clinical outcomes in pts with HRLPC and LIRLPC treated with EBRT suggested substantial additional disease burden in pts with HRLPC and highlights the need for additional strategies and treatments to improve clinical outcomes in pts with HRLPC. [Table: see text]

69 Background: For patients with nmCRPC, APA with androgen deprivation therapy is an important therapeutic option with demonstrated efficacy in improving metastasis-free survival (MFS), and other clinical outcomes. However, there is limited real-world information on these outcomes among patients with nmCRPC treated with APA. This study describes PSA response and MFS among patients with nmCRPC treated with APA in the United States as compared to the SPARTAN registrational trial. Methods: Clinical data from 2/2017 to 4/2022 collected from 77 community-based urology practices were used to evaluate patients with nmCRPC who received ≥1 APA dispensation (index date being the date of first dispensation). Patients were excluded if they had previously used another next-generation antiandrogen or had

65 Background: CR is an important clinical indicator of disease progression and worsening overall survival among pts with mCSPC. This study describes real-world time-to-CR progression in an oncology setting among pts with mCSPC who initiated APA, ENZ, or ABI in the United States. Methods: Clinical data from the Flatiron Metastatic Prostate Cancer (PC) Core Registry Electronic DataMart (1/1/2013 – 07/31/2022) were evaluated. Metastatic pts without evidence of CR before initiating a next-generation androgen inhibitor (AAI) were classified into exclusive treatment cohorts based on the start date (index date) for APA, ENZ, or ABI. CR was identified by a Flatiron algorithm searching for: 1) mention of CR in patient charts, 2) rising prostate-specific antigen (PSA) levels documented from laboratory testing, or 3) mention of rising PSA while on hormonal therapy from unstructured data sources. Pts had ≥12 months (mo) of clinical data pre-index date and were followed from the index date until the end of clinical activity (including death) or data availability. The proportion of pts developing CR was described separately for each cohort using Kaplan-Meier analysis up to 24 mo post-index, with no adjustment for baseline confounders. CR progression rates in the current analysis were descriptively compared to those observed in Phase 3 trials where available. Results: A total of 155 APA, 385 ENZ and 711 ABI pts were evaluated. Mean age at index was ~73 years in each group. Mean follow-up was 12.8 mo (APA), 13.4 mo (ENZ) and 20.6 mo (ABI). Use of androgen deprivation therapy prior to initiation of AAI was observed in ~85% of pts. The median time between documented metastasis and the index date was 2.3 mo (APA), 2.8 mo (ENZ), and 2.3 mo (ABI). Progression rates to CR are shown. By 24 mo, the median time-to-CR was not reached with any treatment studied. By 24 mo, progression to CR was observed in 26% of APA pts in this analysis (32% in TITAN); 36% of ENZ pts in this analysis (25% in ARCHES); and 33% of ABI pts in this analysis (progression to CR not reported in LATITUDE). Conclusions: In this real-world database, the observed proportions of pts progressing to CRPC for the APA and ENZ cohorts were generally consistent with results of Phase 3 trials and include a small proportion of pts with early progression to CRPC. Increased physician awareness of the benefits of early initiation of an AAI along with identification of baseline biomarkers associated with early progression to CRPC may improve clinical outcomes. [Table: see text]

80 Background: Several recurrent mutations that interfere with the HRR DNA damage signaling response pathway have been recently identified as novel biomarkers that may help optimize treatment for patients with mCRPC. There is limited real-world information on clinical outcomes, including TTNT and OS, among patients with mCRPC who initiate 1L, overall and by HRR mutation status in the United States. Methods: This study used the nationwide (de-identified) Flatiron Health – Foundation Medicine Inc. (FMI) Metastatic Prostate Cancer Clinico-Genomic Database (1/1/2011–12/31/2021). The de-identified data originated from approximately 280 US cancer clinics (~800 care sites). Patients who initiated 1L therapy (index date) on or after mCRPC diagnosis and had ≥1 HRR mutation test any time prior to or on the index date were included. Patients were excluded if they initiated a clinical trial drug in 1L or had

410 Background: As use of oral therapies in prostate cancer treatment increases, IOD of oral medication has become more common. The objective of this study was to describe clinical surveillance practices and PSA outcomes in nmCRPC patients (pts) treated in clinics with or without IOD. Methods: nmCRPC pts with ≥1 ARI prescription (Rx) were identified in data from 95 US urology practices between 2018-2021. Pts were categorized into 3 groups: (1) Treated in IOD clinic and received ARI onsite within 14 days of Rx (IOD+), (2) Treated in IOD clinic but no onsite ARI receipt within 14 days of Rx (IOD-), and (3) Treated in a clinic without IOD (non-IOD). Descriptive analyses were conducted on pt characteristics, PSA and imaging data. PSA response, reported using Kaplan-Meier rates, was defined as ≥50% reduction in post-index (PI; index date = 14 days after 1st ARI Rx) PSA compared to baseline PSA (measured within 13 weeks before 1st ARI prescription). PSA progression was defined as ≥25% increase in PI PSA above baseline PSA. Results: 3,300 nmCRPC pts were identified (N = 615 IOD+; 2,474 IOD-; 211 non-IOD). Baseline characteristics differed for race, use of bone resorption agents and 1st generation anti-androgens, and PSA doubling time (PSADT; table). By 6 months PI, PSA screening was observed in similar proportions of pts in IOD and non-IOD, while PSA response was observed in a higher proportion of IOD+ (80%) than IOD- (64%) or non-IOD (63%). PSA progression was observed in fewer IOD+ pts (10%) than IOD- (16%) or non-IOD (17%). PI imaging was conducted in similar proportions of pts in IOD and non-IOD clinics; however, non-IOD performed more imaging per pt and time to imaging was shorter than in IOD+ clinics. Conclusions: Differences were noted in patient characteristics and prior medication use in ARI-treated patients within IOD and non-IOD clinics. IOD+ was observed to have higher rates of PSA response, fewer patients with PSA progression, and use fewer imaging tests after ARI initiation than non-IOD or IOD-. Additional studies controlling for differences in baseline characteristics and examining longer term outcomes are needed to understand how IOD services impact quality of patient care.[Table: see text]

43 Background: Deep prostate-specific antigen (PSA) response, defined as a ≥90% decline in PSA (PSA90), is an important early prognostic factor for achieving radiographic progression free survival and overall survival in patients with metastatic castration-sensitive prostate cancer (mCSPC) treated with a next generation androgen receptor inhibitor (ARI) or androgen biosynthesis inhibitor. This study compared PSA90 responses among patients with mCSPC at first use of a next generation ARI. Methods: Clinical data from 69 community urology practices in the United States were evaluated. Patients with mCSPC were classified into treatment cohorts based on their first filled prescription (index date) for apalutamide (APA) or enzalutamide (ENZ) after 12/16/2019. Patients were followed from index date until the earliest of index regimen discontinuation, treatment switch, end of clinical activity or end of data availability (03/05/2021). Included patients had ≥12 months of clinical activity to assess baseline characteristics. Inverse probability of treatment weighting (IPTW) was used to reduce baseline confounding by controlling for age, race, index year, androgen deprivation therapy (ADT) use ≥6 months, first-generation antiandrogen use, most recent PSA level, most recent testosterone level, Gleason score, and time between metastasis and the index date. PSA90 was defined as the earliest attainment of ≥90% decline in PSA relative to baseline PSA (most recent value within 13 weeks pre-index). The proportion of patients achieving a PSA90 and the time to PSA90 was compared using a weighted Kaplan-Meier (KM) analysis and weighted Cox proportional hazards models. Results: A total of 186 APA patients and 165 ENZ patients met the study criteria. Patients’ characteristics were generally well balanced after IPTW (Table). By 6 months, 73.6% of APA and 69.5% of ENZ patients had a post index PSA measurement. At 6 months, significantly more mCSPC patients initiated on APA attained PSA90 response than patients initiated on ENZ (p=0.014; Table). This result continued to remain significant at 9 months and at the end of the follow-up (Table). The median time to PSA90 was 3.1 months for APA patients and 5.2 months for ENZ patients. Conclusions: This real-world study of mCSPC cohorts demonstrates that initiation of APA leads to significantly more patients achieving a deep PSA response more rapidly than patients initiating ENZ. [Table: see text]

e16784 Background: For localized pancreatic cancer treatment, surgical resection is the only potentially curative option. Currently, little is known about whether racial disparities exist in elderly patients’ access to resection and outcomes after resection. This study aims to understand the relationship between race/ethnicity and both resection rate and survival after surgery in elderly patients. Methods: The analysis included patients aged ≥65 years diagnosed with locoregional resectable (stage I and II according to the 6th AJCC TNM staging system) pancreatic cancer between 2007 and 2016 in the Surveillance, Epidemiology, and End Results database. Patients without complete surgical or survival data were excluded from the analysis. Multiple logistic regression was used to assess the association between race/ethnicity and receipt of resection. The effect of resection on 6-month and 5-year overall survival (OS) was evaluated using multivariate Cox proportional hazards regression, controlling for other clinical and demographic factors, such as sex, age, martial status, residence region, tumor location, tumor size, and year of diagnosis. Results: Of 12,829 patients, 4,310 (46.0%) received resection and 5,062 (54.0%) did not. Median follow-up among resected patients was 16 months (1-60 months), and 6-month and 5-year OS was 62.83% and 4.54%, respectively. The majority of the patients were white (73.1%), followed by Hispanic (9.3%), black (9.1%), and other (American Indian, Asian/Pacific Islander) (8.6%). Black (OR 0.69; 95%CI 0.60-0.80) and Hispanic patients (OR 0.78; 95%CI 0.68-0.90) were less likely to receive resection compared to white patients. While Hispanic patients had worse 6-month OS compared to white patients (HR 1.43; 95%CI 1.19-1.72), 5-year OS was not significantly different across the racial/ethnic groups. Other factors significantly worsened 5-year OS were being age 75 years or older, living in South region, and having tumor size greater than 50mm. Conclusions: Our findings support that racial disparities exist in resection rate in elderly populations. However, no racial difference was seen in the long-term survival after pancreatic resection. This may suggest that improving the access to resection for minorities with pancreatic cancer may improve their health outcomes. [Table: see text]

e19403 Background: The Oncology Care Model (OCM) incentivizes participants to keep episode expenditure below target price; however, little is known about the adequacy of adjustments in target price calculation. This study investigates predictors of increased expenditures and explores how these predictors are associated with exceeding target price for hematologic and solid malignancies. Methods: Non-decedent OCM episodes, categorized as hematologic malignancies (HMs) or solid malignancies (SMs), from 7/1/2016 - 7/1/2018 attributed to our institute were analyzed. Multiple linear regression was used to identify factors associated with increased episode expenditure. Multiple logistic regression was used to evaluate whether such factors increased likelihood of expenditure exceeding target price. Results: Of 1,975 episodes, 499 (25.3%) were HMs and 1,476 (74.7%) were SMs. 54.3% of HMs and 35.2% of SMs had episode expenditure exceeding target price. In HMs, novel therapy use (NT), inpatient admission (INPT), Part B drug use (PB), Part D use (PD), and radiation therapy (XRT) were associated with increased episode expenditure. Of those, INPT and PD increased the likelihood of expenditure exceeding target price. XRT decreased the likelihood of expenditure exceeding target price (Table). In SMs, NT, INPT, emergency department visit, home health aides, durable medical equipment use, PB, PD, XRT, and surgery were associated with increased episode expenditure. Of those, NT, INPT, PB and PD increased the likelihood of expenditure exceeding target price. XRT and receipt of surgery decreased the likelihood of expenditure exceeding target price (Table). Conclusions: INPT and PD significantly increased episode expenditures in both HMs and SMs, leading to expenditures exceeding target prices determined by the OCM benchmark risk-adjustments in both cancer types. NT and PB were significant predictors of increased expenditure and the likelihood of exceeding target price in SMs, but not in HMs. Our findings suggest that there may be opportunities to improve the current model by refining the adjustment for these factors to better reflect real world expenditures. [Table: see text]