Citations

Abstract Background: Advanced prostate cancer is defined as metastatic hormone-sensitive prostate cancer (mHSPC) or castration-resistant prostate cancer (CRPC). Newer and aggressive treatments are leading to increasing lifespans in this population. As such, studying quality of life could have a large impact on the survivorship experience. An important component of quality of life is financial toxicity, defined as the financial burden and distress that can arise for patients and their families because of cancer treatment. Objectives: To understand the prevalence and predictors of financial toxicity in advanced prostate cancer. Methods: IRONMAN (International Registry of Men with Advanced Prostate Cancer) is a prospective cohort of patients with newly diagnosed mHSPC or CRPC enrolling in 15 countries. Financial toxicity was collected using the EORTC QLQ-C30 (“has your physical condition or medical treatment caused you financial difficulties?”) at enrollment and every three months thereafter. For this analysis, we studied 997 patients cared for at 37 US sites enrolled from 7/2017 to 7/2023. We examined baseline and longitudinal reports of financial toxicity across clinical and demographic factors: age at enrollment, race and ethnicity, disease state, marital status, education, employment, military status, and type of health center. We conducted adjusted risk difference analysis and multivariable regression modeling to identify predictors of financial toxicity using a generalized estimating equations approach to calculate odds ratios (OR and 95% confidence intervals, CI). Results: At enrollment, 125 (13%) patients reported experiencing “quite a bit” or “very much” financial toxicity. 21% of Black patients experienced toxicity compared to 10% of White patients. Even after incorporating all other predictors, Black patients experienced 5% (95% CI: 0, 11) greater toxicity than White patients. Independently of other predictors, patients >75 experienced 11% (CI: -17, -4) lower toxicity compared to those <65 years (while patients in the 65-74 group experienced 6% less, CI: -12, 1). Toxicity was 6% greater in patients with mHSPC (CI: 2, 10) than in patients with CRPC, and disabled or unemployed patients were at substantially higher risk. In the multivariable longitudinal analyses, older age (> 75) remained associated with significantly lower odds for financial toxicity (OR: 0.30, 0.15-0.61) while mHSPC (OR: 1.91, 1.14-3.20) and being unemployed (OR: 2.69, 1.03-6.99) or disabled (OR: 5.14, 2.29-11.6) were associated with higher odds. Conclusions: Financial toxicity is prevalent in advanced prostate cancer, especially in patients who are Black, younger than 75, diagnosed with mHSPC, or unemployed/disabled. These results may inform identification of patients at high risk for financial toxicity to support delivery of patient-situation-informed care by clinicians and targeted aid for patients at highest risk. Citation Format: Isani Singh, Bailey Vaselkiv, Emily Rencsok, Karen Autio, Deborah Enting, Alicia Morgans, Joel Nowak, Kevin Kensler, David Nanus, Robert Dreicer, Brian Lewis, Oliver Sartor, Elisabeth Heath, Phillip Kantoff, Deborah Kaye, Daniel George, Lorelei Mucci. Financial toxicity among patients with advanced prostate cancer in the United States [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3410.

Abstract Background: Metastatic castration-resistant prostate cancer (mCRPC) resistant to androgen receptor (AR)-targeted agents is often lethal. Unfortunately, biomarkers for this deadly disease remain under investigation, and underpinning mechanisms are ill-understood. Here, we applied epigenomic approaches to identify cell-free (cf) DNA features associated with these lethal AR-resistant mCRPC patients. Methods: Plasma from 99 mCRPC patients was collected from two independent institutions, either prior to first-line AR-targeted therapy (n = 63) or during treatment (n = 36). We applied EnhanceAR-Seq to detect alterations in the AR locus including the upstream enhancer. We then applied genome-wide cfDNA epigenomics to 43 pre-treatment plasma samples and performed both fragmentomics and methylation sequencing to delineate the biology of AR/enhancer-altered lethal mCRPC. Finally, we identified stemness genes by applying CytoTRACE to external single-cell RNA-seq data from mCRPC, and applied these to cfDNA via promoter-level methylation analysis. We then assessed these stem-associated genes in tumor bulk RNA-seq data from an independent mCRPC cohort. Results: AR/enhancer alterations were detected in 44% of pre-treatment cfDNA samples and correlated with significantly worse progression-free survival (PFS) (HR = 2.12, P = 0.01) and overall survival (OS) (HR = 2.48; P = 0.02). AR/enhancer alterations were detected in 19% of on-treatment cfDNA samples and were also associated with profoundly worse PFS (HR = 15.38, P = 0.0003) and OS (HR = 15.53, P = 0.002). Further, genome-wide cfDNA fragmentomic analysis revealed that binding sites for developmentally relevant transcription factors such as FOXA1, NKX-3 and HOXB13 were significantly more accessible in AR/enhancer-altered lethal mCRPC patients. Gene set enrichment analysis of the 20 most accessible transcription factors revealed several pathways associated with stem cell development. Interestingly, the 10 most stem-associated genes obtained using CytoTRACE applied to an external cohort of single-cell RNA-seq data from mCRPC (He et al. 2021) were promoter-hypomethylated in the plasma cfDNA of AR/enhancer-altered lethal mCRPC patients (P = 0.005). Further, metagene analysis of these stem-associated genes revealed worse PFS by Kaplan-Meier analysis (P = 0.04), which was confirmed by multivariate cox proportional hazards modeling. Our stemness metagene further stratified overall survival (P = 0.03) when applied to an external cohort of 80 mCRPC patients from Abida et al. 2019. Conclusions: Alterations in AR including the upstream enhancer are remarkably prognostic in mCRPC with pre-treatment predictive potential. The mechanism can be inferred via cfDNA epigenomic analysis and appears to involve increased tumor cell stemness in AR-altered lethal mCRPC. Citation Format: Pradeep Singh Chauhan, Irfan Alahi, Savar Sinha, Ryan Mueller, Alexander L. Shiang, Jace Webster, Ha X. Dang, Debanjan Saha, Lilli Greiner, Breanna Yang, Elisa M. Ledet, Ramandeep K. Babbra, Wenjia Feng, Peter K. Harris, Faridi Qaium, Ellen B. Jaeger, Patrick J. Miller, Sydney A. Caputo, Oliver A. Sartor, Russell K. Pachynski, Christopher A. Maher, Aadel A. Chaudhuri. Epigenomic analysis of plasma cell-free DNA identifies stemness features associated with worse prognosis in AR-altered lethal metastatic castration resistant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 983.

Abstract A 78-year-old man receiving bicalutamide for prostate cancer was referred for a PSMA PET/CT scan to evaluate his gradually rising prostate-specific antigen level. The PSMA PET/CT revealed gynecomastia with radiotracer uptake in bilateral breast parenchyma, a known but rarely reported effect of bicalutamide monotherapy. This scan also demonstrated metastatic progression of his disease in bone and lymph nodes, and he was started on leuprolide injections. Three months after a decrease in his testosterone level, the radiotracer uptake in his breast tissue had resolved, demonstrating that PSMA-avid bicalutamide-induced gynecomastia is reversible.

TPS246 Background: Prostate cancer (PC) is common and despite recent advances in treatment options, patients with metastatic disease still have poor outcomes, warranting the development of new effective therapies in this setting. Prostate-specific membrane antigen (PSMA) is expressed in benign and malignant prostate tissues and luminal surface of salivary/lacrimal glands, small intestine and renal tubules. The double PSMA binding moiety of SAR-bisPSMA in 64Cu-SAR-bisPSMA (imaging) and 67Cu-SAR-bisPSMA (therapy) may offer advantages compared to currently used single-target PSMA agents. Clinical evidence demonstrated 2-3 times higher uptake of 64Cu-SAR-bisPSMA compared to the single-target PSMA agent, 68Ga-PSMA-11. Pre-clinical efficacy data of 67Cu-SAR-bisPSMA in mice showed statistically significant tumor growth inhibition compared to the control group as well as a dose-dependent delay in eventual tumor regression in a PC xenograft study. These results led to the development of this clinical study, which aims to assess safety and anti-tumor efficacy of 67Cu-SAR-bisPSMA in patients with metastatic castrate resistant PC (mCRPC). Methods: SECuRE is a phase I/IIa multi-center, open-label, non-randomized, dose-escalation and cohort expansion study of 64Cu-SAR-bisPSMA and 67Cu-SAR-bisPSMA. mCRPC patients with progression, prior exposure to at least one androgen receptor pathway inhibitor, and positive 64Cu-SAR-bisPSMA PET may be treated with 67Cu-SAR-bisPSMA. This study is being conducted in 3 phases: a 64Cu-SAR-bisPSMA Dosimetry Phase (n=6), a 67Cu-SAR-bisPSMA Dose Escalation Phase (n=up to 24), and a 67Cu-SAR-bisPSMA Cohort Expansion Phase (n=14). The primary and key secondary objectives include assessment of 64Cu- and 67Cu-SAR-bisPSMA safety and dosimetry, determining the maximum tolerated dose (MTD) or maximum feasible dose (MFD) and anti-tumor efficacy of 67Cu-SAR-bisPSMA. The 67Cu-SAR-bisPSMA dose levels investigated in the escalation phase include: 4 GBq (cohort 1, single dose), 8 GBq (cohort 2, single dose), 12 GBq (cohort 3, single dose) and up to 24 GBq across two doses (cohort 4, two doses at MTD or MFD). The Dose Expansion Phase of the study will allow the administration of up to 4 doses of 67Cu-SAR-bisPSMA at the MTD/MFD. Response measurements include reduction in PSA levels, radiological progression-free survival, duration of response and overall survival. Radiological response will be assessed by RECIST 1 V1.1 and PCWG3. At the time of submission of this abstract, cohort 3 is open for recruitment and no dose limiting toxicities have been observed to date. Clinical trial information: NCT04868604 .

93 Background: The treatment paradigm for mCSPC patients has rapidly evolved over the last few years with the emergence of triplet therapy and prognostication by volume of disease. However, the health economic implications of triplet therapy by disease volume remain unclear. Methods: A Markov model where patients transitioned between the progression-free, progression and death states was developed. State utilities were derived from the LATITUDE trial. Point probabilities for overall survival, progression-free survival, grade ≥ 3 and 5 toxicities were obtained from the eligible mCSPC phase III clinical trials. Medicare Advantage and commercial total paid amounts (2022 US$) of treatments were obtained from OptumLabs Data Warehouse. Costs and disutilities of adverse events were derived from published literature. Half-cycle corrected costs and utilities were accrued monthly over a 20-year lifetime horizon and were discounted at 3%. Monte Carlo simulation was used to calculate incremental cost-effectiveness ratios (ICERs). A willingness-to-pay (WTP) threshold of US$100,000 was used. Results: In terms of Medicare Advantage payer’s perspective (Table), docetaxel (D)+ADT was observed to provide additional 0.068 QALYs compared to ADT at an ICER of US$16,544 per QALY in high volume disease. Compared to D+ADT, abiraterone (AAP) triplet provided additional 1.03 QALYs at US$56,641 per QALY. Compared to AAP triplet, apalutamide (APA)+ADT provided additional 0.048 QALYs at US$5,846,248 per QALY in high volume disease. In low volume disease, D+ADT provided 0.45 more QALYs at US$20,690 per QALY compared to ADT alone. Compared to D+ADT, AAP triplet provided an additional 1.51 QALYS at US$44,267 per QALY. In terms of total paid commercial costs, AAP triplet provided an additional 1.19 QALYs compared to ADT at US$91,952 per QALY in high volume disease. In low volume, D+ADT provided additional 0.38 QALYs at US$22,058 per QALY compared to ADT. Compared to D+ADT, AAP triplet provided a 0.97 QALY gain at US$105,958 per QALY. Compared to AAP triplet, darolutamide (DARO) triplet provided a 0.47 QALY at US$689,196 per QALY. Compared to DARO triplet, APA+ADT provided an additional 0.49 QALYs at an ICER of US$971,389 per QALY. All other treatments (not reported here) were dominated. Conclusions: At the selected WTP of US$100,000 per QALY, AAP triplet therapy was most likely the cost-effective strategy in overall mCSPC population particularly in patients with high volume disease. However, these results should be interpreted with careful accounting for timing of metastases. [Table: see text]

49 Background: Ductal carcinoma (DC) is the second most commonly encountered histologic variant of prostate cancer. Previous studies have described its molecular features and aggressive behavior, but few have explored the performance of PSMA PET/CT in the initial staging and follow-up of DC. Methods: To address this gap, we performed a single-institution retrospective analysis using the Mayo Clinic PSMA PET database. All patients receiving a PSMA PET/CT scan in the interval of January 1, 2021, to December 31, 2022, were eligible for inclusion. Cases were filtered and categorized by histology at the time of diagnosis to select for pure DAC and mixed ductal variants. Trained research personnel annotated disease- and treatment-related variables. A board-certified radiologist performed tumor burden segmentation with calculations of SUV max, total lesion SUV mean and volume, and total lesion uptake, and ascribed a miPSMA expression score. Results: We queried 1792 patients from our PSMA PET/CT registry and identified 32 (1.8%) patients with a pathologically confirmed DC, including 8 (25%) patients with pure ductal and 25 (75%) patients with mixed histology. The indication for PSMA PET/CT was biochemical progression or restaging for 29 (91%) patients and initial staging for 3 (9%) patients. The median (IQR) time from prostate cancer diagnosis to PSMA PET scan was 41.6 (11.5-64.7) months, during this time 50% (n= 16) of patients developed CRPC. At the time of the PSMA PET/CT scan, the median age was 70 years, the median (IQR) PSA was 0.5 ng/mL (0.2-2.6). The distribution of metastatic spread and quantitative imaging parameters from PSMA PET are shown in the Table. Conclusions: Despite low PSA at the time of imaging, PSMA PET/CT frequently detected high volume osseous and/or visceral metastases in patients with DC. However, it is noteworthy that more than 50% of patients with DC had a low miPSMA score (0-1). Additional studies are needed to better understand the performance of novel imaging modalities when evaluating variant prostate cancers. [Table: see text]

320 Background: sRT is used in men with prostate cancer (PC) recurrence following radical prostatectomy (RP) signaled by a persistent or delayed elevation in PSA. It was previously reported that the use of AAT with RT improved cancer control and overall survival (OS). Long-term follow-up (FU) results are presented here. Methods: From 1998to 2003, 760 eligible post-RP patients with Stage pT3N0 or with pT2N0 and positive margins and PSA from 0.2 to 4.0 ng/mL were randomly assigned on a double-blinded, placebo-controlled trial of RT + placebo vs. RT + anti-androgen therapy (AAT) (24 months of bicalutamide, 150mg daily) during and after RT (64.8 Gy in 36 fractions prostate bed). The primary endpoint was OS estimated using Kaplan-Meier method. Time to PC death and metastatic PC (competing risk of death without an event) was estimated using cumulative incidence. The hazard ratio (HR) was obtained using Cox models (OS) and subdistribution HRs (sHRs) used the Fine-Gray model (time to PC death and metastatic PC). All tests are one-sided based on study design. Results: Median FU for surviving patients was 19 years. OS at 18 years was 53% [95% confidence interval (CI): 47-58%] for RT + AAT and 43% [95% CI: 38-48%] for RT + placebo (adjusted HR 0.82 [95% CI: 0.67-1.00], p = 0.025). The 18-year incidence of centrally reviewed PC deaths were 18% [95% CI: 14-22%] RT + AAT and 28% [95% CI: 23-32%] RT + placebo (adjusted sHR = 0.57 [95% CI: 0.42-0.78], p<0.001). The 18-year incidence of metastatic PC was 22% [95% CI: 18-26%] and 31% [95% CI: 26-35%] for AAT and placebo arms respectively with adjusted sHR = 0.59 [95% CI: 0.44-0.80, p<0.001]. Subgroup analyses is shown in the Table. Conclusions: Long term results of 24-month duration AAT during and after sRT are consistent with the primary report with significantly improved long-term OS, reduced incidence of metastatic PC and PC death for RT+AAT. Statistically significant metastatic PC was noted for Gleason score 8-10, study entry PSA>1.5 and margin positive patients and borderline significance was observed in patients with study entry PSA 0.7-1.5. Clinical trial information: NCT00002874 . [Table: see text]

220 Background: There is a critical need to identify biomarkers of response and resistance to 177Lu-PSMA-617. Post-hoc analyses of VISION have explored the prognostic and predictive value of select clinical parameters. However, we are still in the early stages of deciphering which molecular changes are associated with favorable or adverse treatment outcomes. Methods: We conducted a retrospective analysis of patients with metastatic castration-resistant prostate cancer (mCRPC), who received 177Lu-PSMA-617 at Mayo Clinic in Rochester, Minnesota, in the interval of March 2022 to March 2023. We included patients who provided research authorization, had a baseline PSA of at least 2 ng/mL, received at least 2 cycles of treatment, and had circulating tumor DNA (ctDNA) genomic profiling performed by Guardant (83 gene panel) within 60 days of treatment initiation. Clinical, laboratory, genomic, and radiomic parameters were abstracted by trained research personnel. Two independent analyses of “response” and “resistance” were performed. Response to treatment was defined as 50% or greater decrease in PSA from baseline (PSA50 response: dichotomized yes versus no), and resistance was defined as non-decreasing or rising PSA during treatment (PSA non-response: dichotomized yes versus no). Associations between gene alterations and response and resistance were evaluated via Fisher’s exact tests. Results: Between March 2022 and March 2023, 273 patients received cycle 1 of 177Lu-PSMA-617. A total of 108 patients met the inclusion criteria. The median number of cycles at data cutoff was 6 (IQR: 4,6) with 57 (53%) patients receiving all 6 planned cycles. The median PSA at baseline was 16.65 ng/ml (IQR: 5.20, 66.12). A total of 65 patients (60%) experienced a PSA50 response. No molecular alterations were associated with a higher rate of PSA50 response; however, alterations in ARID1A, AR, and CHEK2 were associated with lack of PSA50 response (Fisher’s exact p < 0.05). Of the 108 evaluable patients, 20 (19%) met criteria for PSA non-response. Alterations in AR, ARID1A, MYC, TP53, CHEK2, ATM, EGFR, and NOTCH1 were significantly associated with PSA non-response (Fisher’s exact p < 0.05); in each case, the presence of the alteration was positively associated with resistance (i.e., more instance of PSA non-response). No biomarkers were found to be inversely associated with PSA non-response. Conclusions: ctDNA assessed by commercially available, targeted sequencing panels prior to treatment may be useful in identifying the patients least likely to benefit from 177Lu-PSMA-617. Further work is ongoing to integrate ctDNA findings with clinical parameters in the hopes of understanding the factors mediating response and resistance to therapy.

216 Background: PCa harbors recurrent FOXA1 alterations, yet distinct alteration types may drive divergent consequences. Here, we established several classes of FOXA1 alterations and evaluated their clinical outcomes, molecular correlates, and immunologic landscape in a large cohort of primary and metastatic PCa samples from Caris Life Sciences. Methods: We interrogated the Caris DNA (592-gene/whole exome) and RNA (whole transcriptome) NGS databases. FOXA1 alterations were annotated based on amino acid (a.a.) location and prior functional studies (Table). Real-world overall survival (OS) was determined from insurance claims data using Kaplan-Meier estimates. Gene set enrichment analyses (GSEA) was used to estimate signaling pathway activity. Immune-cell fractions were inferred from bulk RNA-seq using quanTIseq. All comparisons are made relative to FOXA1 WT cases. Results: The overall prevalence of FOXA1 alterations was 16%, with no enrichment in metastatic PCa samples (15.5%). Class 2 mutations were enriched in histologic NEPC, were associated with a classical NEPC mRNA signature, and showed poor survival with ADT (HR 5.6, 95% CI: 2.5–12.5, p<0.001). Conversely, metastatic PCa patients with Class 1B mutations had numerically improved survival with ADT (HR 0.76, 95% CI: 0.50–1.14, p=0.18). All FOXA1 alterations (except Class 2) resulted in increased FOXA1 transcripts, with 1B and 1C having the greatest effects (q<0.0001). Class 0 and 3 alterations had 2–5 fold higher frequency of TMB-high and MSI-high status (q<0.05). Conversely, Class 1B exhibited lower TMB and markedly fewer TP53 mutations (35.7% vs 20.3%, q<0.001) and TMPRSS2-ERG fusions (34.5% vs 4.6%, q<0.001). Class 1B was depleted of AR transcriptional signatures (q=0.01) but enriched of MYC signaling in GSEA analysis (FDR<0.001), and showed reduced expression of B7-H3. On immune-cell deconvolution analysis, Class 1B showed reduced dendritic cells, but increased B cells and neutrophils (DC: 1.96% vs 0.01%, B cell: 4.27% vs 5.29%, neutrophils: 5.05% vs 8.00%, each q<0.001). Conclusions: Different FOXA1 alterations exhibit divergent molecular and clinical features, and should not be interpreted in aggregate. In particular, Class 1B mutations are associated with a unique molecular and immunological landscape with potentially better outcomes to ADT, while Class 2 mutations are associated with NEPC phenotype with inferior ADT sensitivity. [Table: see text]

212 Background: Patients with prostate cancer with liver metastases are known to have a worse prognosis. In this study, we evaluated ctDNA in mCRPC (metastatic castration-resistant prostate cancer) patients with and without liver metastases. Methods: A retrospective chart review identified mCRPC patients with liver metastases at Tulane Cancer Center and Huntsman Cancer Institute. Liver metastases were confirmed via molecular or conventional imaging. All patients had ctDNA assessed with a multi-gene cancer panel via the Guardant 360 assay. Alterations with <0.1% allelic fraction, synonymous alterations, and variants of unknown significance were excluded from analyses. Statistical analyses were performed using Fisher’s Exact and Wilcoxon Rank Sum Tests. Correction for multiple testing was not performed, hence these alterations may be subject to a type 1 error. Results: 53 mCRPC patients with liver metastases and 144 mCRPC patients without liver metastases were included in the study. We found seven genes that are more likely to be pathologically altered in ctDNA in mCRPC patients with liver metastases (See Tables 1-3): AR (OR=2.38, 95% CI: [1.25, 4.52], p=0.01), BRAF (OR=2.74, 95% CI:[1.05, 7.18], p=0.05), BRCA2 (OR=5.33, 95% CI:[1.49, 19.02], p=0.01), CDK6 (OR=4.09, 95% CI:[1.35, 12.42], p=0.01), EGFR (OR=3.12, 95% CI:[1.22, 7.99], p=0.02), FGFR1 (OR=5.69, 95% CI:[1.81, 17.86], p-value=0.003), MYC (OR=4.55, 95% CI:[1.63, 12.68], p=0.004), and PIK3CA (OR=4.34, 95% CI:[1.87, 10.06], p=0.01). Additionally, mCRPC patients with liver metastases are more likely to have copy number alterations (CNA) (p= 0.01) compared to mCRPC patients without liver involvement. There were no other significant differences in the remaining 70 genes interrogated. Germline pathogenic alterations did not vary between the two groups. Conclusions: In mCRPC patients with liver metastases, these exploratory analyses suggest ctDNA testing is more likely to detect pathologic alterations in AR, BRAF, BRCA2, CDK6, EGFR, FGFR1, MYC, and PIK3CA. Additionally, mCRPC patients were more likely to have copy number alterations (CNA). Limitations of the Guardant 360 assays are notable in this setting given the incomplete ascertainment of gene deletions and the incomplete number of prostate-relevant genes assessed. [Table: see text]