Castration-sensitive Prostate Cancer Research Articles

Demonstrating Bioequivalence for Two Dose Strengths of Niraparib andAbiraterone AcetateDual-Action Tablets Versus Single Agents: Utility of Clinical Study Data Supplemented with Modeling and Simulation.

The combination of niraparib and abiraterone acetate (AA) plus prednisone is under investigation for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) and metastatic castration-sensitive prostate cancer (mCSPC). Regular-strength (RS) and lower-strength (LS) dual-action tablets (DATs), comprising niraparib 100 mg/AA 500 mg and niraparib 50 mg/AA 500 mg, respectively, were developed to reduce pill burden and improve patient experience. A bioequivalence (BE)/bioavailability (BA) study was conducted under modified fasting conditions in patients with mCRPC to support approval of the DATs. This open-label randomized BA/BE study (NCT04577833) was conducted at 14 sites in the USA and Europe. The study had a sequential design, including a 21-day screening phase, a pharmacokinetic (PK) assessment phase comprising three periods [namely (1) single-dose with up to 1-week run-in, (2) daily doseon days 1-11, and (3) daily dose ondays 12-22], an extension where both niraparib and AA as single-agent combination (SAC; reference) or AA alone was continued from day 23 until discontinuation, and a 30-day follow-up phase. Patients were randomly assigned in a parallel-group design (four-sequence randomization) to receive a single oral dose of niraparib 100 mg/AA 1000 mg as a LS-DAT or SAC in period 1, and patients continued as randomized into a two-way crossover design during periods 2 and 3 where they received niraparib 200 mg/AA 1000 mg once daily as a RS-DAT or SAC. The design was powered on the basis of crossover assessment of RS-DAT versus SAC. During repeated dosing (periods 2 and 3, and extension phase), all patients also received prednisone/prednisolone 5 mg twice daily. Plasma samples were collected for measurement of niraparib and abiraterone plasma concentrations. Statistical assessment of the RS-DAT and LS-DAT versus SAC was performed on log-transformed pharmacokinetic parameters data from periods 2 and 3 (crossover) and from period 1 (parallel), respectively. Additional paired analyses and model-based bioequivalence assessments were conducted to evaluate the similarity between the LS-DAT and SAC. For the RS-DAT versus SAC, the 90% confidence intervals (CI) of geometric mean ratios (GMR) for maximum concentration at a steady state (Cmax,ss) and area under the plasma concentration-time curve from 0-24 h at a steady state (AUC 0-24h,ss) were respectively 99.18-106.12% and 97.91-104.31% for niraparib and 87.59-106.69 and 86.91-100.23% for abiraterone. For the LS-DAT vs SAC, the 90% CI of GMR for AUC0-72h of niraparib was 80.31-101.12% in primary analysis, the 90% CI of GMR for Cmax,ss and AUC 0-24h,ss of abiraterone was 85.41-118.34% and 86.51-121.64% respectively, and 96.4% of simulated LS-DAT versus SAC BE trials met the BE criteria for both niraparib and abiraterone. The RS-DAT met BE criteria (range 80%-125%) versus SAC based on 90% CI of GMR for Cmax,ss and AUC 0-24h,ss. The LS-DAT was considered BE to SAC on the basis of the niraparib component meeting the BE criteria in the primary analysis for AUC 0-72h; abiraterone meeting the BE criteria in additional paired analyses based on Cmax,ss and AUC 0-24h,ss; and the percentage of simulated LS-DAT versus SAC BE trials meeting the BE criteria for both. NCT04577833.

Prostate-specific antigen (PSA) decline with apalutamide therapy is associated with longer survival and improved outcomes in individuals with metastatic prostate cancer: a plain language summary of the TITAN study.

This summary describes the results from an additional (or post hoc) analysis of the TITAN study. The TITAN study looked at whether the prostate cancer treatment apalutamide could be used to treat individuals with metastatic castration-sensitive prostate cancer (or mCSPC). A total of 1052 participants with mCSPC were included in the TITAN study. Treatment with apalutamide was compared with treatment with placebo. All participants received androgen deprivation therapy (or ADT), which is a type of hormone therapy that has been part of the main treatment for mCSPC for many years. The results showed that apalutamide plus ADT increased the length of time that participants remained alive compared with placebo plus ADT. Apalutamide plus ADT also controlled the growth of the cancer for a longer length of time compared with placebo plus ADT. Additionally, participants who received apalutamide plus ADT experienced a greater reduction in the blood levels of prostate-specific antigen (or PSA), called a deep PSA decline, compared with those who received placebo plus ADT. An additional (or post hoc) analysis was carried out to understand whether a decrease in blood PSA levels, in response to treatment, was associated with improved outcomes, including longer survival time. In participants who received apalutamide plus ADT, a deep PSA decline in response to treatment was associated with longer survival time and improved outcomes. These results demonstrate that individuals with mCSPC can benefit from treatment with apalutamide plus ADT. The association seen between deep PSA decline and the longer survival time and improved outcomes highlights how PSA measurements can be used to help monitor cancer disease evolution in response to treatment. Monitoring PSA levels will assist doctors and other healthcare professionals to understand how effectively a treatment is working for a patient and to tailor their treatment approach to improve PSA decline.

Characterizing the real-world economic burden of metastatic castration-sensitive prostate cancer in the United States

Aims To describe healthcare resource utilization (HRU) and costs of patients with metastatic castration-sensitive prostate cancer (mCSPC). Methods Linked data from Flatiron Metastatic PC Core Registry and Komodo’s Healthcare Map were evaluated (01/2016-12/2021). Patients with chart-confirmed diagnoses for metastatic PC without confirmed castration resistance in Flatiron who initiated androgen deprivation therapy (ADT) monotherapy or advanced therapy for mCSPC in 2017 or later (index date) with a corresponding pharmacy or medical claim in Komodo Health were included. Advanced therapies considered were androgen-receptor signaling inhibitors, chemotherapies, estrogens, immunotherapies, poly ADP-ribose polymerase inhibitors, and radiopharmaceuticals. Patients with <12 months of continuous insurance eligibility before index were excluded. Per-patient-per-month (PPPM) all-cause and PC-related HRU and costs (medical and pharmacy; from a payer’s perspective in 2022 $USD) were described in the 12-month baseline period and follow-up period (from the index date to castration resistance, end of continuous insurance eligibility, end of data availability, or death). Results Of 871 patients included (mean age: 70.6 years), 52% initiated ADT monotherapy as their index treatment without documented advanced therapy use. During baseline, 31% of patients had a PC-related inpatient admission and 94% had a PC-related outpatient visit; mean all-cause costs were $2551 PPPM and PC-related costs were $839 PPPM with $787 PPPM attributable to medical costs. Patients had a mean follow-up of 15 months, during which 38% had a PC-related inpatient admission and 98% had a PC-related outpatient visit; mean all-cause costs were $5950 PPPM with PC-related total costs of $4363 PPPM, including medical costs of $2012 PPPM. Limitations All analyses were descriptive; statistical testing was not performed. Treatment effectiveness and clinical outcomes were not assessed. Conclusion This real-world study demonstrated a significant economic burden in mCSPC patients, and a propensity to use ADT monotherapy in clinical practice despite the availability and guideline recommendations of advanced life-prolonging therapies.

Real-World Incidence and Severity of Hypertension Caused by Abiraterone Acetate in Patients With Metastatic Prostate Cancer.

Abiraterone acetate (AA) is used in treatment of patients with metastatic prostate cancer. Despite the survival advantage, AA is associated with hypertension due to mineralocorticoid excess syndrome. We conducted a single-center retrospective analysis to evaluate the real-world incidence and severity of AA-induced hypertension. Electronic health records were used to collect baseline characteristics and prostate cancer history. Patient data, including blood pressure at each 4 (±2)-week interval, were collected for 24 weeks after the initiation of AA therapy. The primary endpoint was the incidence and severity of AA-induced hypertension. The secondary endpoints include effect of different prednisone dosing regimens and prostate cancer types on hypertensive incidence and the impact of clinical pharmacists' involvement in managing AA-induced hypertension. A total of 142 patients who met our inclusion criteria received AA for metastatic prostate cancer, 73 (51.4%) with metastatic castration-resistant prostate cancer (mCRPC), and 69 (48.6%) with metastatic castration-sensitive prostate cancer (mCSPC). Of all, 43.7% experienced all-grade hypertension, and 28.2% experienced grade 3-4 hypertension. There was no difference in incidence of hypertension between patients receiving 5 mg of prednisone daily and those receiving 5 mg of prednisone twice daily. All-grade hypertension occurred in 39.7% of mCRPC and 47.8% of mCSPC patients (P = 0.33). Thirty-two percent of patients were actively managed by a clinical pharmacist and had an overall trend of reduced hypertension severity after 12 weeks. This single-center, retrospective cohort study found that real-world metastatic prostate cancer patients who received AA had substantially higher incidence and severity of hypertension compared with clinical trials regardless of prednisone dose. In patients with mCRPC and mCSPC, the role of prednisone dose in hypertension incidence and severity warrants further investigation. Overall, results indicate the need for closely monitoring hypertension and optimization of anti-hypertensive therapy by multidisciplinary teams in metastatic prostate cancer patients receiving AA.

ERBB3 Overexpression is Enriched in Diverse Patient Populations with Castration-sensitive Prostate Cancer and is Associated with a Unique AR Activity Signature.

Despite successful clinical management of castration-sensitive prostate cancer (CSPC), the 5-year survival rate for men with castration-resistant prostate cancer is only 32%. Combination treatment strategies to prevent disease recurrence are increasing, albeit in biomarker-unselected patients. Identifying a biomarker in CSPC to stratify patients who will progress on standard-of-care therapy could guide therapeutic strategies. Targeted deep sequencing was performed for the University of Illinois (UI) cohort (n = 30), and immunostaining was performed on a patient tissue microarray (n = 149). Bioinformatic analyses identified pathways associated with biomarker overexpression (OE) in the UI cohort, consolidated RNA sequencing samples accessed from Database of Genotypes and Phenotypes (n = 664), and GSE209954 (n = 68). Neutralizing antibody patritumab and ectopic HER3 OE were utilized for functional mechanistic experiments. We identified ERBB3 OE in diverse patient populations with CSPC, where it was associated with advanced disease at diagnosis. Bioinformatic analyses showed a positive correlation between ERBB3 expression and the androgen response pathway despite low dihydrotestosterone and stable expression of androgen receptor (AR) transcript in Black/African American men. At the protein level, HER3 expression was negatively correlated with intraprostatic androgen in Black/African American men. Mechanistically, HER3 promoted enzalutamide resistance in prostate cancer cell line models and HER3-targeted therapy resensitized therapy-resistant prostate cancer cell lines to enzalutamide. In diverse patient populations with CSPC, ERBB3 OE was associated with high AR signaling despite low intraprostatic androgen. Mechanistic studies demonstrated a direct link between HER3 and enzalutamide resistance. ERBB3 OE as a biomarker could thus stratify patients for intensification of therapy in castration-sensitive disease, including targeting HER3 directly to improve sensitivity to AR-targeted therapies.

ERBB3 expression in racially diverse patients with castration-sensitive prostate cancer and its association with a unique AR activity signature.

23 Background: Despite successful clinical management of castration sensitive prostate cancer (CSPC), the 5-year survival rate for men with castration-resistant prostate cancer (CRPC) is only 32%. This number is even more striking in the context of racial disparities where prostate cancer mortality rates for Black/African American (AA) men are two to four times higher than those in every other racial and ethnic group in the US. Identification of molecular expression and activity patterns that vary by racial group may provide a key to addressing outcomes related to survival disparities, as current treatments have not been developed with attention to the inclusion of diverse patient populations. Developing a biomarker in CSPC to stratify patients who will progress on standard-of-care therapy could guide intelligent intensification of therapeutic strategies and improve survival, particularly in high-risk patient populations. Methods: Targeted deep sequencing was performed as routine care for treatment naïve patients in the UI cohort (n=30), and immunostaining was performed in racially diverse tissue microarray (n=149). Bioinformatics analyses were utilized to identify signaling pathways associated with biomarker overexpression in the UI cohort, consolidated publicly available RNA-seq datasets (n=664), and a racially diverse Gene Expression Omnibus dataset (n=68). Results: We identified ERBB3 overexpression (OE) in racially diverse CSPC patient populations, where it was associated with advanced disease at diagnosis. At the protein level, HER3 expression was negatively correlated with intraprostatic androgen in Black/AA men. Bioinformatics analyses showed a positive correlation between ERBB3 expression and the Androgen Response pathway despite low intraprostatic androgen and stable expression of androgen receptor (AR) transcript in Black/AA men. Clinically, ERBB3 OE is associated with high pre-treatment serum PSA in Black/AA men and is positively correlated with a clinically adaptable AR signature score. Preliminary outcomes data suggest Black/AA men with ERBB3 OE have a shorter time to disease progression. Conclusions: In diverse CSPC patient populations, ERBB3 OE was associated with high AR signaling and serum PSA despite low intraprostatic androgen, suggesting ERBB3 OE as a prospective biomarker for ligand-independent AR activation. In this context, ERBB3 OE could stratify patients for intensification of therapy in castration-sensitive disease and emphasizes the importance of biomarker-directed clinical trials with diverse populations.

ARAMON: A phase 2, randomized, open-label study comparing darolutamide (DARO) vs enzalutamide (ENZA) monotherapy on serum testosterone levels in patients (pts) with castration-sensitive prostate cancer (CSPC) after biochemical recurrence (BCR).

TPS243 Background: DARO, a structurally distinct and highly potent androgen receptor inhibitor, has low blood–brain barrier (BBB) penetration and limited potential for drug–drug interactions. In phase 3 trials, DARO showed significant efficacy and a favorable safety profile. In ARAMIS (NCT02200614), DARO and androgen-deprivation therapy (ADT) significantly improved metastasis-free survival and overall survival (OS) vs placebo + ADT in pts with nonmetastatic castration-resistant prostate cancer. In ARASENS (NCT02799602), DARO + ADT + docetaxel significantly improved OS in pts with metastatic hormone-sensitive prostate cancer vs placebo + ADT + docetaxel. In both studies, the incidence of adverse events (AEs) was similar between treatment groups. Currently, the ARASTEP study (NCT05794906) is evaluating DARO and ADT in pts with high-risk BCR following primary therapy who have prostate-specific membrane antigen PET/CT-positive lesions. Based on a neuroimaging study of healthy volunteers, cerebral blood flow was not altered with DARO but was significantly reduced in brain areas related to cognition with ENZA. It is postulated that the low BBB penetration of DARO may result in lower serum testosterone elevations than those seen with ENZA, which may reduce the frequency of AEs. The ARAMON study (NCT05526248) will compare the effect of DARO and ENZA monotherapy on post-treatment testosterone levels in pts with CSPC who developed a BCR after definitive treatment for localized disease. Methods: ARAMON is a two-stage, open-label, phase 2 study of pts with histologically or cytologically confirmed adenocarcinoma of the prostate who experienced BCR after radical primary prostatectomy (RP) or radiation therapy (RT), with &lt;5 asymptomatic oligometastatic disease sites. Key inclusion criteria are prostate-specific antigen (PSA) ≥2 ng/mL, PSA doubling time of ≤20 months, serum testosterone &gt;150 ng/dL, and Eastern Cooperative Oncology Group performance status 0/1. During the lead-in phase, 25 pts will receive DARO 600 mg twice daily for 52 weeks. If serum testosterone criteria are met at 12 weeks, the study will proceed to the randomized phase where approximately 40 pts will be randomized 1:1 to DARO (600 mg twice daily) or ENZA (160 mg once daily) for 52 weeks. The primary endpoint is the change in serum testosterone level from baseline to Week 12. Secondary endpoints include the change in serum testosterone levels from baseline to Weeks 24 and 52; PSA at Weeks 4, 12, 24, 36, and 52; changes in blood levels of endocrine, glycemic, and lipid metabolism markers; incidence of AEs; and quality of life. As of September 2023, 23 of 25 planned pts in the lead-in phase have been enrolled. Clinical trial information: NCT05526248 .

Role of Bone Scan Index (BSI) in the Prognosis and Treatment Efficacy in Castration-Sensitive Prostate Cancer Patients with Bone Metastasis

Bone is the most common metastatic site in prostate cancer (PCa). Although the extent of disease (EOD) grade is used for evaluating burden of bone metastasis, the accuracy of bone metastasis classification needs improvement. Bone scan index (BSI) was developed as a quantitative tool to enhance the interpretability and clinical relevance of the bone scan. This study aimed to explore the role of BSI using BONENAVI® software in determining the prognosis and treatment efficacy in castration-sensitive PCa (mCSPC) patients with bone metastasis. We retrospectively reviewed 61 mCSPC patients with bone metastasis who had received primary androgen deprivation therapy (PADT) at our institution. All patients received PADT with luteinizing hormone-releasing hormone agonist or surgical castration accompanied by first-generation antiandrogen, bicalutamide. Bone scans were performed with ⁹⁹[m]Tc-MDP. BSI (%) was divided into two groups (＜1.0 and ≧1.0), and BSI response rates(change at 0 months to after 6 months) were determined using thresholds of 45% decline. Castration-resistant prostate cancer (CRPC) -free survival (CRPC-FS) and Overall survival (OS) rates were analyzed using the Kaplan-Meier method. The median follow-up was 41. 9 months. Overall, 16 patients (26. 2%) died. Multivariate analysis on pretreatment factors revealed that hemoglobin (P＝0.03) and BSI (P＝0.04) were independent prognostic factors for OS. The 5-year OS rates in patients with low BSI and high BSI were 84.6% and 39.2%, respectively (P＝0.02). In 40 patients who had a bone scan before and after PADT, OS rates in patients with a good response (≧45%) were significantly higher than those with a poor response (＜45%) (P＝0.001). Nadir PSA titers within 6 months after the start of treatment (P＝0.005), Hb (P＝0.003), and BSI change (P＝0.014) were independent prognostic factors for OS. In mCSPC patients with bone metastases, BSI at diagnosis was an important predictor of CRPC progression and OS as a pre-treatment factor, and BSI change rate and PSA nadir as post-treatment factors.

A real-world observational study characterizing patients (pts) with metastatic castration-sensitive prostate cancer (mCSPC) treated with or without androgen receptor pathway inhibitors (ARPIs).

59 Background: mCSPC treatment is rapidly evolving with androgen deprivation therapy (ADT) plus ARPIs viewed as the standard of care for most pts. Data are needed to understand the real-world characteristics and treatment patterns of mCSPC (PC) pts in this dynamic field. This study aimed to define clinical features of mCSPC pts, estimate the proportion of pts receiving ARPIs, and evaluate clinical and demographic features associated with ARPI use. Methods: This retrospective cohort study used data from electronic health records and administrative databases in the province of Alberta, Canada. All newly diagnosed metastatic PC pts between 2017-2020 were identified. Pts were considered to have mCSPC if they initiated ADT within 30 days prior to, or at any time after diagnosis. ARPI exposure was defined as receiving ARPI within 180 days of initiating ADT. ARPI-naïve pts may have received ADT alone or other non-ARPI therapy (i.e., docetaxel) within 180 days of initiating ADT. Multivariable logistic regression was used to evaluate pt characteristics related to the receipt of ARPI. Overall survival (OS) was defined as the date of diagnosis to death from any cause or last known contact. Results: Of the 976 mCSPC pts identified, 33.5% received an ARPI. In ARPI exposed pts, the median time from ADT to ARPI start was 7.9 weeks and median time on ARPI was 13.1 months (mos). In multivariable analyses, ARPI use was associated with younger pt age, more recent diagnosis, fewer comorbidities, a higher metastatic burden, treatment centre, referral to a medical oncologist, and prior local therapy (all p&lt;0.05). The median time to next therapy was 24.6 mos (95%CI=19.5-33.0) vs. 18.5 mos (95%CI+16.9-21.1), and median OS was 38.5 mos (95%CI=32.8-NA) vs. 34.2 mos (95%CI=33.3-38.8) for APRI exposed vs. ARPI-naive pts, respectively (p=0.03). Conclusions: This study identified factors associated with ARPI use in mCSPC, potentially allowing targeted efforts to improve ARPI uptake for pts in whom use is low. These findings are important as they reflect outcomes seen in real world pts.

Characteristics and outcomes of patients (pts) with metastatic castration-sensitive prostate cancer (mCSPC) showing a primary resistance (PR) to docetaxel (DOC): Results from a large real-world database.

158 Background: ECHOS trial is a large real-world study, which is collecting data on mCSPC patients treated in the daily clinical practice in Italy from 2015. To date, &gt; 1500 pts were included in the study, most of them treated with DOC, according to the availability of the active agents over the time in Italy. In the present analysis, we assessed the characteristics and outcomes of mCSPC pts progressing within 6 mos from the start of DOC. Methods: We retrospectively and prospectively reviewed the clinical records of a consecutive series of mCSPC pts treated with DOC in the daily clinical practice in 69 Italian Hospitals. The treatment mostly consisted of DOC at the standard dose of 75 mg/sqm every 3 wks for six courses. For each pt we recorded the pre and post-DOC clinical history, the baseline characteristics of the pts, the treatment details and clinical outcomes. For the purpose of the present study, we considered only pts who ended chemotherapy by September 2022. PR was defined as the onset of progressive disease within 6 mos from the DOC start. Results: Among 920 mCSPC pts treated with DOC, 122 (14.3%) were PR. Most of them (95.6%) presented a de novo (DN) disease, which showed mostly high volume (HV) features (82.3%). Compared to the pts without PR, those showing PR presented more frequently a visceral involvement (26.2% vs 18.2%; p = 0.038), had lower baseline levels of hemoglobin (12.8 g/dl vs 13.4 g/dl; p &lt; 0.0001), and higher baseline levels of lactate dehydrogenase (266 U/L vs 220,5 U/L; p &lt; 0.002). No other significant differences were observed in terms of baseline PSA and alkaline phosphatase levels, symptoms degree, disease volume and timing of mets presentation between PR e no-PR pts. The median number of life prolonging agents administered after DOC progression was 1 in pts with PR as well as in pts without PR. The median overall survival was 11.9 mos and 44.9 mos in PR and no-PR pts, respectively (p &lt; 0.0001). Conclusions: Our data suggest that PR led a significant worsening of prognosis with a relevant shortening of life expectancy in pts who receive DOC for mCSPC.

Comparative survival in metastatic castration-sensitive prostate cancer (mCSPC) by prognostic subgroups: A living network meta-analysis.

171 Background: Treatment effects vary by volume of disease and timing of metastatic presentation in patients with mCSPC. Therefore, we updated the existing body of evidence to assess the comparative efficacy of systemic therapy in mCSPC by prognostic subgroups to inform clinical practice guidelines. Methods: This living systematic review was conducted using the living interactive evidence (LIvE) synthesis framework. Phase III clinical trials assessing contemporary systemic therapy in mCSPC and reporting overall survival (OS) by four prognostic subgroups were included. Prognostic subgroups included synchronous high volume (SHV), synchronous low volume (SLV), metachronous high volume (MHV), and metachronous low volume (MLV) disease. Mixed treatment comparisons were made using a network-meta-analytic approach in each subgroup. P-scores were used to assess relative treatment rankings in congruency with pairwise estimates. Higher scores indicated better efficacy. Results: This study included a total of nine trials with eight unique treatment options. In patients with SHV disease, darolutamide+docetaxel+ADT (DARO+D+ADT) significantly improved OS when compared to D+ADT (HR: 0.69; 0.57-0.85), enzalutamide (E)+ADT (HR: 0.67; 95% CI: 0.46-0.99), and apalutamide (APA)+ADT (HR: 0.65; 95% CI: 0.43-0.96). In patients with SLV disease, E+ADT (HR: 0.62; 95% CI: 0.42-0.91) and AAP+ADT (HR: 0.66; 95% CI: 0.49-0.89) significantly improved OS when compared to ADT. Although E+D+ADT trended toward improvement compared to other treatments, the results were not statistically significant. In patients withMHV disease, no statistically significant differences were observed among mixed treatment comparisons. However, OS with DARO+D+ADT trended toward improvement when compared to D+ADT (HR: 0.69; 95% CI: 0.39-1.23), APA+ADT (HR: 0.72; 95% CI: 0.23-2.33), E+ADT (HR: 0.67; 95% CI: 0.24-1.86), and E+D+ADT (HR: 0.59; 95% CI: 0.26-1.34). In patients with MLV disease, E+ADT significantly improved OS compared to ADT (HR: 0.51; 95% CI: 0.32-0.79), and D+ADT (HR: 0.48; 95% CI: 0.27-0.85). APA+ADT significant improved OS compared to ADT (HR: 0.22; 95% CI: 0.09-0.54), and D+ADT (HR: 0.21; 95% CI: 0.08-0.55). No other statistically significant differences were observed among mixed treatment comparisons. Conclusions: Current evidence suggests that triplet systemic therapy may be preferred in SHV, E systemic triplet and E hormonal doublet in SLV, DARO systemic triplet and APA hormonal doublet in MHV, and APA or E hormonal doublets in MLV mCSPC. [Table: see text]

Barriers and facilitators to first-line (1L) treatment intensification (TI) in metastatic castration-sensitive prostate cancer (mCSPC): The IMPLEMENT study.

224 Background: Despite evidence of benefits and guideline recommendations for first-line treatment intensification (ie, androgen-deprivation therapy with chemotherapy, novel hormonal therapies, or both) in mCSPC, it is underutilized. We examined barriers and facilitators that US urologists and oncologists face with treatment intensification for mCSPC and identified behavior change techniques to address these through an implementation science approach. Methods: We conducted 36 double-blind, semi-structured, virtual interviews with practicing US urologists and oncologists who manage mCSPC using an interview guide based on the theoretical domains framework. Saturation was met when no new themes emerged. Physician statements were coded into 11 domains and themes to identify barriers and facilitators. To confirm codebook reliability, 10% of transcripts were double coded independently (k=0.77). Key domains and the associated barriers and facilitators were analyzed for frequency, perceived potential to impact behavior, and presence of disagreement. Top domains were cross-referenced with a taxonomy of validated behavior change techniques. Results: 36 interviewed physicians (20 low intensifiers[≤50% of patients get treatment intensification]; 16 high intensifiers [&gt;50% of patients get treatment intensification]), 14 (39%) were from academic centers. Five impactful domains and the associated barriers and facilitators were identified along with behavior change techniques to overcome them (Table). Conclusions: Underutilization of treatment intensification in US is multifactorial. Poor knowledge, habit, anticipated regret, costs, and reserving treatment intensification for later use were prominent barriers. These can be addressed through behavior change techniques to improve mCSPC care. [Table: see text]

Analysis of real-world survival for patients with metastatic castration-sensitive prostate cancer (mCSPC) treated with apalutamide (APA) or abiraterone acetate (ABI) in an oncology database: ROMA study.

58 Background: Androgen receptor signaling inhibitors (ARSI), including APA and ABI plus prednisone, are approved for the treatment of mCSPC. However, studies evaluating survival for these agents in clinical trials or the real-world have not been investigated. This study describes real-world survival among men with mCSPC who initiated APA or ABI in the United States (US). Methods: Data from the Flatiron Metastatic Prostate Cancer (PC) Core Registry Electronic DataMart (1/1/2013–05/31/2023) was used to identify ARSI-naïve patients with chart-confirmed metastasis and without evidence of castration resistance at ARSI initiation. Patients were classified into two treatment cohorts based on the start date for APA or ABI (index date) on/after 9/17/2019. Patients had ≥12 months of clinical data pre-index and were followed from the index date until the earliest of 24 months post-index, end of clinical activity, or end of data availability. Patients’ date of death was obtained by integrating data from electronic medical records, the Social Security Death Index, and or other confirmed sources. Using an intention-to-treat approach, Kaplan-Meier analysis was used to describe the proportion of patients surviving by 24 months post-index. An unadjusted Cox proportional hazards model was used to describe crude differences in survival rates between patients initiating APA and ABI. Results: This study included 242 APA (mean age: 73.0 years; 60.3% White, 13.6% Black) and 607 ABI (mean age: 73.1 years; 57.3% White, 16.8% Black) patients. APA median time on-treatment was 11.4 months over a median observation period of 14.3 months. ABI median time on-treatment was 10.8 months over a median observation of 14.0 months. By 24 months, 85.7% of the APA cohort and 75.9% of the ABI cohort were living (unadjusted hazard ratio=0.60, 95% confidence interval: 0.38, 0.96; p=0.033; Table). Conclusions: In this study, we observed that more ARSI-naïve patients with mCSPC survived by 24 months after initiating APA than those who initiated ABI. While the current study presents unadjusted comparisons, additional causal analyses controlling for confounding variables should be conducted to confirm these initial findings. [Table: see text]

A phase IIa study of sequential ("first strike, second strike") therapies, modeled on evolutionary dynamics of anthropocene extinctions, for high-risk metastatic castration-sensitive prostate cancer.

A phase IIa study of sequential ("first strike, second strike") therapies, modeled on evolutionary dynamics of anthropocene extinctions, for high-risk metastatic castration-sensitive prostate cancer.

Understanding variation in treatment intensification for de novo metastatic castration-sensitive prostate cancer (mCSPC): A population-based cohort study.

69 Background: Treatment intensification using androgen receptor signaling inhibitors (ARSIs) or chemotherapy is guideline-recommended for patients with mCSPC based on improved survival and preserved quality of life. However, numerous studies across jurisdictions have shown relatively limited uptake, with most patients receiving androgen deprivation therapy (ADT) monotherapy. Therefore, we sought to understand patient, physician, and tumor characteristics associated with treatment intensification. Methods: This population-based cohort study in Ontario, Canada included older men (age ≥66 years) diagnosed with de novo mCSPC between Jan 2014 and Nov 2021 for whom the ADT-prescribing physician could be identified (&gt;99.5% of all mCSPC patients). We used hierarchical regression modelling to assess the association (presented as odds ratio, OR) between patient sociodemographic characteristics and comorbidities, tumor characteristics, and physician characteristics with receipt of intensified treatment for mCSPC, defined as receipt of an ARSI, docetaxel, or both within 6mo. We used Darlington’s method to assess the relative importance of these predictors (presented as standardized regression coefficients, SRC). Results: Among 4450 eligible older men newly diagnosed with de novo mCSPC, 18.8% received treatment intensification, with rates increasing from 6.3% in 2014 to 31.9% by 2021. In multivariable modeling, patient age was the most influential variable, with older patients significantly less likely to receive treatment intensification (SRC -43.8, OR 0.91, 95% CI 0.90-0.92). Socioeconomic status (SRC -12.2; OR 0.54, 95% CI 0.33-0.88 for quintile 1 vs 5) and a history of stroke (SRC -11.5, OR 0.28, 95% CI 0.09-0.86), but no other patient factors including comorbidity, were significantly associated with intensification. Patients prescribed ADT for mCSPC by radiation oncologists were less likely to receive intensification (SRC -16.5; OR 0.47, 95% CI 0.23-0.95) compared to other providers without significant differences between patients treated by urologists, medical oncologists, or other physicians. No other physician-level characteristic (age, sex, years in practice, or annual volume of prostate cancer patients) was associated with treatment intensification. More contemporary year of diagnosis was also strongly predictive (mean SRC 31.2) of intensification. We noted significant geographic variation (mean SRC 10.2; p&lt;0.0001), that could not be explained by rurality (p=0.08) and persisted after adjustment for socioeconomic status and patient characteristics. Conclusions: Patient, disease, and physician characteristics contribute to variation in treatment intensification for mCSPC. These data may allow focused intervention to improve guideline-concordant care for patients with mCSPC.

Real-world survival of men with metastatic castration-sensitive prostate cancer (mCSPC) initiated on apalutamide (APA) or enzalutamide (ENZ) in an oncology database: ROME Study.

57 Background: Androgen receptor signaling inhibitors (ARSIs), including APA and ENZ, have demonstrated progression-free and overall survival benefits for men with mCSPC in the clinical trial setting, but data evaluating real-world treatment effectiveness remains limited. The aim of this study was to describe real-world survival among men with mCSPC who initiated APA or ENZ in the United States (US). Methods: In this retrospective longitudinal cohort study, clinical data from the Flatiron Metastatic Prostate Cancer (PC) Core Registry Electronic DataMart (1/1/2013–05/31/2023) were used. Patients with chart-confirmed metastasis and without castration resistance were classified into two treatment cohorts based on earliest initiation of APA or ENZ on/after 12/16/2019 (index date). Patients had ≥12 months of clinical data pre-index and were followed from the index date until the earliest of 24 months post-index, end of clinical activity, or end of data availability. Patients’ date of death was obtained from electronic medical records, Social Security Death Index, or other confirmed sources. Using an intention-to-treat approach, Kaplan-Meier analysis was used to describe the proportion of patients surviving by 24 months post-index. An unadjusted Cox proportional hazards model was used to describe crude differences in survival rates between patients initiating APA and ENZ. Results: There were 234 APA (mean age: 73.2 years; 59.8% White, 13.7% Black) and 527 ENZ (mean age: 73.9 years; 55.2% White, 13.1% Black) patients included in this study (Table). APA median time on-treatment was 10.9 months over a median observation period of 13.3 months, while ENZ median time on-treatment was 11.1 months over a median 14.8 months observation period. By 24 months, a higher proportion of patients in the APA cohort survived than in the ENZ cohort (85.4% vs 73.9%; unadjusted hazard ratio=0.59, 95% confidence interval: 0.39, 0.95; p=0.030; Table). Conclusions: In this real-world analysis of patients with mCSPC, more patients treated with APA survived by 24 months following treatment initiation as compared to treatment with ENZ. While the current study reports unadjusted analyses, future studies adjusting for potential confounding variables should be conducted to confirm these findings in order to inform clinicians on treatment selection for patients with mCSPC. [Table: see text]

Prostate-specific antigen (PSA) response among patients with metastatic castration-sensitive prostate cancer (mCSPC) initiated on apalutamide (APA) or abiraterone acetate (ABI) in real-world urology practices.

53 Background: Recently approved oral therapies APA and ABI (plus prednisone) are effective mCSPC treatments. Prior real-world evidence showed that, relative to ABI, patients who initiated APA had significantly higher rates of PSA decline ≥90% (PSA90), which has been associated with longer overall survival. The objective of this study was to compare PSA90 response among an enhanced cohort of patients with mCSPC initiated on APA or ABI. Methods: Electronic medical records from PPS Analytics including data from US community urology practices were linked with administrative claims from the Komodo Health Solutions Research Database. Androgen receptor signaling inhibitor (ARSI)-naïve patients with mCSPC with ≥12 months of pre-index clinical activity were selected into the APA or ABI cohort based on their first paid claim/dispensation on or after 17 Sep 2019 (index date). Patients were followed to earliest of index ARSI discontinuation or switch, radiopharmaceutical use, end of insurance or clinical activity, or end of data availability (30 Sep 2022). Inverse probability treatment weighting (IPTW) was used to reduce potential pre-index confounding, controlling for age, race, region, insurance payer, index year, time from metastasis to index date, time from first prostate cancer (PC) diagnosis to index date, metastasis locations, de novo PC, use of androgen deprivation therapy, first-generation antiandrogens or chemotherapy, most recent PSA and testosterone levels, and most recent Gleason score. PSA90 was defined as the earliest attainment of ≥90% decline in PSA relative to pre-index (most recent value within 13 weeks). The proportion of patients achieving PSA90 was compared using a weighted Kaplan-Meier analysis and the time-to-PSA90 response was compared using a weighted Cox proportional hazards model. Results: A total of 917 APA and 632 ABI patients were identified. Patient characteristics were balanced with IPTW (Table). By 6 months post-index, 80.9% of APA and 72.8% of ABI patients had a PSA measurement. By 6 months, significantly more APA patients attained a PSA90 response, as compared to ABI patients (P &lt; 0.001; Table). Median time-to-PSA90 was 3.5 months for APA patients and 8.8 months for ABI patients. Conclusions: This real-world study supports previous findings that a greater percentage of patients with mCSPC in the US initiating APA achieved deep PSA response compared to those initiating ABI. [Table: see text]

Adverse outcomes (AOs) in patients (pts) with metastatic castration-sensitive prostate cancer (mCSPC) treated with intensified androgen deprivation therapy (ADT+).

113 Background: mCSPC pts experience adverse outcomes (AOs) with intensified androgen deprivation, resulting in treatment discontinuation; however, there is limited data to identify those at risk. The IRONMAN registry is a global initiative to enroll advanced prostate cancer patients worldwide, and survey data on AOs, patient-reported outcomes (PROs), and clinico-epidemiologic (demographic, cancer, and treatment) details. We report the prevalence and predictors of AOs from baseline demographic, clinical, and PRO information with the onset of AOs and present a risk prediction model for clinical use. Methods: We analyzed data from 553 mCSPC patients in the IRONMAN registry from inception to March 2023 who received ADT+ alone (Abiraterone 47.6%, Enzalutamide 26.9%, Apalutamide 22.6%, Darolutamide 2.9%) and had completed baseline PROs. We defined AOs, reported by 60 global sites, as non-progression-related clinically significant serious adverse events (csSAE), treatment discontinuation, and dose reductions (DR/DC), delineated as a composite outcome based on first event. We processed baseline variable groups: Demographics (race, ethnicity, marital status, study site), Clinical Factors (age, ECOG score, metastatic sites, ADT+, concurrent medications, labs [ALP, Hb, LDH, and PSA]), Concurrent therapies (steroid use within 30 days [d] &amp; steroid dose, radiation/surgery prior or planned in 6months) and PROs (EORTC QLQ-C30 and EPIC-23). We developed a multifactorial logistic regression model to predict adverse outcomes (AOs) within two years of initiating ADT+ therapy. All variables with less than 25-30% missing data were included. Variable selection was conducted in two layers: intra-group stepwise selection followed by an inter-group selection of variables retained from the first layer. The model's discriminatory ability was evaluated using the area under curve (AUC). Results: 553 pts met inclusion (51.6% North America, 72% White, mean age: 71 years [range, 40 to 96 years], and 62.9% confirmed bone-metastatic mCSPC). 119 pts (21.5%) developed AOs (61 csSAEs [18 dead; Median: 140 d; IQR 81-360 d], 58 DR/DC [Median: 122 d; IQR 43-262 d]). &lt;5% went off study. The multifactorial model (n=314 pts) performed well at predicting AOs (AUC 0.77 [0.70-0.84]), with significant factors being more self-reported pain, greater urinary frequency, prednisone&gt;5mg within 30d, more self-reported weakness and poor sexual function within 3 months of ADT+ initiation. Conclusions: 1 in 5 mCSPC patients on ADT+ experienced non-progression-related AOs at 2 years. Significant, easily assessed predictive factors are identified and may be utilized in their clinical management. A novel multifactorial model is presented to predict AOs at 2 years. Further validation, assessment of missingness bias, and imputation are planned.

Association of initial adjustment dose of apalutamide with progression to castration-resistant prostate cancer and skin-adverse events in men with metastatic castration-sensitive prostate cancer: A multicenter retrospective study of CsJUC cohort.

137 Background: Japanese patients with prostate cancer (PC) treated with apalutamide often encounter skin-adverse events (AE), which might lead to adjust the initial-dose of apalutamide. However, concerns have emerged regarding the potential impact of these dose adjustments on the overall efficacy of apalutamide in real-world clinical practice. We aimed to evaluate the association between adjustment of apalutamide dose and clinical outcome in Japanese men with metastatic castration-sensitive PC (mCSPC). Methods: We retrospectively evaluated 108 mCSPC patients treated with apalutamide. We divided patients into two groups: initial full-dose and reduced-dose recipients. The primary outcome was the impact of apalutamide dose adjustment on progression to castration-resistant prostate cancer (CRPC) and PSA response. The secondary outcomes were the impact of apalutamide dose adjustment on the incidence of the skin-AE. Results: Initial reduced-dose recipients of apalutamide were observed in 16.7%. There were no differences in cancer characteristics, such as CHAARTED criteria between the groups. Initial full-dose recipients were significantly associated with a longer time to CRPC than initial reduced-dose recipients [median NA (NA - NA) vs. 19 months (95% CI, 10 - NA), P=0.0161], although the percentages of the initial full-dose recipients who reduced apalutamide dose were 30%, 44.4%, 60%, and 63.3% at 3, 6, 9, and 12 months, respectively. The percentage of PSA &lt;0.2 decline at 3 months did not differ between the groups (59.1% vs 50%, P=0.602), but overall PSA 90% decline was higher in the initial full-dose recipients (88.8% vs 66.7%, P=0.027). Skin-AE occurred 50% in initial reduced-dose recipients and 51.1% in initial full-dose recipients, with no difference between the groups (P&gt;0.999). Furthermore, time to skin-AE was not different between the groups (74 days vs. 69 days, P=0.992). Conclusions: Our study suggested the potential negative implications of initial apalutamide dose adjustments on clinical outcomes in Japanese men with mCSPC.

What criteria do clinicians use to classify men as “high risk” among patients with biochemically recurrent nonmetastatic castration-sensitive prostate cancer?

300 Background: In patients with biochemically recurrent (BCR) nonmetastatic castration-sensitive prostate cancer (nmCSPC), guidelines support the use of clinical factors such as prostate-specific antigen doubling time (PSADT) and Gleason score to identify high-risk patients who are more likely to develop metastases and could benefit from earlier intervention. The current study aimed to understand criteria used by physicians in the real-world to categorize patients with BCR nmCSPC as high-risk. Methods: This analysis used data from the Adelphi Real World nmCSPC retrospective survey, completed by urologists and radiation oncologists in the US. Physicians extracted data from medical charts for their last 6–8 patients diagnosed with high-risk BCR nmCSPC since January 2021 (until July 2023). A physician attitudinal survey was also completed. Data were analyzed descriptively. Results: Overall, 84 physicians provided data (68 urologists; 16 radiation oncologists). When asked in general (not patient specific) to name clinical factors used to determine level of risk, physicians cited using multiple factors, most frequently PSADT (93%), Gleason score (88%), absolute PSA rise following definitive therapy (86%), and clinical stage (85%). PSADT was cited as the single most important clinical factor by nearly 50%, followed by Gleason score, clinical stage, and absolute PSA rise following definitive therapy (Table). For physicians who used PSADT to risk stratify, the median (IQR) threshold for high-risk was 6 (6–9) months. Aggregated patient-level data were analyzed for 352 patients with high-risk BCR nmCSPC, as defined by the physicians. Clinical factors used to classify patients as having high-risk BCR in this study included PSADT (58%), Gleason score (44%), absolute PSA rise after definitive therapy (42%), clinical stage (21%), and pathological findings at radical prostatectomy (15%). Overall, 65% of patients had a PSADT ≤9 months after BCR, and 68% had a PSADT &lt; 12 months (high-risk per the AUA guidelines). Conclusions: Physicians reported using multiple clinical factors to classify patients as having high-risk BCR nmCSPC, with PSADT considered the most important for risk stratification. Appropriate and timely identification of patients as high-risk may help to identify patients for whom earlier intervention could be beneficial.[Table: see text]