PSA Response Research Articles

Phase Ib trial of enzalutamide (Enza) with venetoclax (Ven) in metastatic castration-resistant prostate cancer (mCRPC).

182 Background: Androgen receptor (AR) signaling is critical to prostate cancer (PCa) cell survival and proliferation. Androgen ablation leads to expansion of both AR−/lo and AR+/hi resistant clones in CRPC xenografts. Most current therapies for mCRPC are directed towards AR+/hi cells. BCL-2 is highly up-regulated in CRPC xenografts and human tumors post-Enza. Ven, a selective BCL-2 inhibitor, inhibits Enza resistance in AR−/lo and CRPC models. We hypothesize that co-targeting AR−/lo and AR+/hi clones with Ven and Enza may inhibit Enza resistance in human mCRPC. Methods: This is a phase 1b single center, single arm trial of fixed dose Enza (160mg/d) with escalating doses of Ven in patients with mCRPC that has progressed on multiple lines of prior therapies including antiandrogens to evaluate pharmacokinetics, safety and recommended phase 2 dose. A total of 10 patients were enrolled in the study. Three dose levels of Ven (400mg (DL1), 600mg (DL2), and 800mg (DL3)/d q28d) were evaluated using a 3+3 study design. Kaplan Meier method was used to estimate median overall survival (OS) and time to next systemic therapy (TNST). Results: Median age was 71.3 years and mean duration on treatment was 28.7 weeks (range: 8-140 weeks). On an average, each patient received 3 lines of treatment prior to enrollment(range:1-8). The most frequent treatment related adverse events (TRAEs) (>10%) were mostly grade 1-2 as listed. Grade 3 TRAEs included hypertension (20%), fatigue (10%), and thrombocytopenia (10%). Grade 3 fatigue as DLT was reported in one patient in DL3. Only 1/10 (10%) attained PSA50 response; 4/10 (40%) patients had stable disease and 6/10 (60%) had disease progression as their best radiographic response. Median OS for the study population was 18.8 months (95% CI 5.3-28.2 months) and median TNST was 5.4 months (95% CI 0.9-34.6 months). Conclusions: This phase 1b trial demonstrates an acceptable toxicity profile for the combination of Enza and Ven in refractory mCRPC. PK evaluations and correlative biomarker studies are currently ongoing. Clinical trial information: NCT03751436 . [Table: see text]

Efficacy of subsequent treatments in patients who progressed to mCRPC following treatment with apalutamide for nonmetastatic castration-resistant prostate cancer (nmCRPC): A post-hoc analysis of the SPARTAN phase III trial.

157 Background: Apalutamide (Apa) delays the onset of metastases and extends survival in nmCRPC. However, the benefit of subsequent therapy for metastatic castration resistant prostate cancer (mCRPC) following progression on Apa remains inadequately explored. Methods: A post-hoc analysis of SPARTAN, a randomized phase III (NCT01946204), double-blind, placebo-controlled trial with Apa for the treatment of men with nmCRPC was undertaken in order to assess the impact of post-protocol treatment. Patients included in this analysis were SPARTAN patients who developed mCRPC while on Apa and received a first subsequent therapy for mCRPC (the “Next Cohort”). The index date of the analysis was the initiation of first subsequent treatment for mCRPC. The baseline characteristics of the Next Cohort (reported from the time of initial randomization because updated characteristics at the index date could not be derived) were compared to those of the ITT Apa arm in SPARTAN. Subsequent overall survival (sOS) and subsequent progression-free survival per physician assessment (sPFS) were calculated from the index date using Kaplan-Meier method. Results: At study completion, 237 patients remained on Apa without progression, while 311 were included in the Next Cohort. Of these, 241 (77.5%) received abiraterone acetate plus prednisone (AAP) provided by the sponsor as an option as first subsequent treatment, 29 (9.3%) received docetaxel; 20 (6.4%) enzalutamide and 21 other treatments (6.8%). Compared to the ITT Apa arm in SPARTAN, a higher proportion of the Next Cohort had PSA doubling time ≤6 months (79.1% vs 71.5%) and a PSA value above median at baseline, and experienced poorer PSA response (51% PSA90 overall response rate vs 62%) whilst on apalutamide treatment. The median sPFS and sOS were 6.8 months (95% confidence interval, CI, 5.8-7.9) and 20.0 months (95% CI, 17.0-22.6), respectively. Choice of subsequent next treatment did not appear to have an impact on sPFS and sOS. Conclusions: Limitations of this analysis include its retrospective nature and the lack of randomization to first line mCRPC therapy and related potential confounding, and the inclusion of patients who had progressed at SPARTAN study completion with associated poorer prognosis. Nevertheless, the analysis suggests comparable efficacy of selected first line mCRPC therapies, following progression on Apa for nmCRPC. Clinical trial information: NCT01946204 . [Table: see text]

Health disparities in metastatic hormone-sensitive prostate cancer (mHSPC) presentations and outcomes among Hispanic Americans (HA) versus non-Hispanic Whites (NHW).

31 Background: Multiple retrospective studies conducted have demonstrated disparities in access to care and treatment rates for prostate cancer between HA and NHW. We sought to understand the differences in prostate cancer presenting characteristics, prognosis, and outcomes between the two ethnic groups who presented to the University of Arizona Cancer Center (UACC), which serves a large Hispanic community. Methods: A retrospective analysis of mHSPC adenocarcinoma patients who presented to UACC from 2016 to 2022 was conducted. Patients must have had genetic testing to be included. Patients with no metastasis and incomplete data were excluded. Continuous data were analyzed using t-tests or Wilcoxon Rank sum tests depending on whether they were normally distributed. Categorical variables were analyzed using X2 Tests or Fisher's exact tests. Time to Event data was analyzed using Kaplan-Meier Methods. Results: 83 patients were included with 38.5% HA. No difference was observed between the ethnic groups by median age at presentation (66 years), race (90% white), obesity (40% BMI>30), personal cancer history (10%), or family history of cancer (48%). HA were more likely to have a smoking (69%) and alcohol (63%) history compared to NHW (54% and 39%, respectively; p= 0.04). On presentation, 56% of HA were ECOG 0 compared to 22% of NHW (p=0.001). At the time of diagnosis, HA had median PSA levels of 111.5 ng/ml compared to 52.6 ng/ml in NHW (p=0.12). Gleason Grade Group ≥4 in 73% HA vs 79% in NHW (p=0.61). 41% of HA presented with T4 disease compared to 14% of NHW (p=0.01). 69% of HA presented with N1 disease vs 61% of NHW (p=0.85). 41% of HA presented with visceral metastasis, M1c, compared to 16% of NHW (p=0.04). The median time to first-line (1L) treatment was 1 month in HA compared to 3 months for NHW (p<0.01). 84% of all patients had 1L combination therapy. Abiraterone plus ADT was 1L in 47% of HA compared to 20% of NHW (p=0.06). ADT plus androgen receptor blocker was 1L in 41% of NHW compared to 28% of HA (p=0.06). Median PSA response 3 months after starting treatment was 0.8 ng/ml in HA vs 3.96 ng/ml NHW (p=0.05). The median time to 2L was 20 months for HA vs 11 months in NHW (p=0.05). Conclusions: HA in our study presented with higher PSA, more locally advanced disease, and increased rates of visceral metastases, necessitating a shorter time interval to 1L therapy. HA demonstrated a more favorable response to 1L treatment, noted by lower PSA at 3 months and time to the next line of treatment. Overall survival was not calculated due to the small sample size with only 11 (1 HA vs 10 NHW) total deaths. The Hispanic Americans Prostate Cancer Comprehensive Genomic Profiling Study's (THAPCA-GPS) future investigations aim to delineate the pathogenetic differences between HA and NHW and may reduce healthcare disparities and improve clinical outcomes in HA patients.

Tumor transcriptomic profiling of patients (pts) with metastatic castration sensitive prostate cancer (mCSPC) who do versus who do not achieve an optimal PSA response to intensified androgen deprivation therapy (i-ADT).

234 Background: Pts with mCSPC receiving i-ADT and achieving a PSA nadir ≤0.2 ng/mL (PSA-L) demonstrate significantly better overall survival (OS) as compared to those with a PSA nadir > 0.2 ng/mL (PSA-H) (Chi AUA 2021, Saad ASCO 2022). We hypothesized that tumor gene expression profile would differ between PSA-L and PSA-H. Methods: In this IRB-approved retrospective study, eligibility criteria included confirmed mCSPC receiving i-ADT with androgen receptor-axis-targeted therapy (ARAT) and availability of RNAseq profiling performed by a CLIA-certified lab of primary prostate biopsies collected before treatment. Pts were divided into 2 groups: PSA-L and PSA-H based on achieving a PSA nadir ≤0.2 ng/mL at any time during treatment course. The DEseq2 pipeline was used to analyze differentially expressed genes between the groups. The data included the Log2 fold change, Wald-Test p-values, and Benjamini-Hochberg adjusted p values (q values) for each differentially expressed gene. These results were subjected to Gene Set Enrichment Analysis (GSEA) to identify pathways enriched in each cohort. All bioinformatic analysis was undertaken using R studio v4.2. Results: 78 pts were eligible: 55 were PSA-L, and 23 were PSA-H. The most significantly upregulated pathways in PSA-L were the TNFA signaling, androgen response (AR), estrogen response, and interferon-alpha response pathways. The most upregulated pathways in PSA-H were epithelial-mesenchymal transition, coagulation, and bile acid metabolism pathways. Normalized enrichment scores are reported in the table. Differential individual gene expression profiles will be presented at the meeting. Conclusions: These hypothesis-generating data show that mCSPC pts on i-ADT with PSA-L have distinct baseline tumor gene expression profiles, such as upregulation of AR signaling, compared to pts with PSA-H. After external validation, these findings may help personalize medicine prior to initiation of therapy in pts not expected to achieve PSA-L. [Table: see text]

Intra-individual dose escalation of abiraterone (ABI) according to its plasma exposure in patients (pts) with progressive metastatic castration-resistant prostate cancer (mRCPC): Results of the OPTIMABI trial.

159 Background: Abiraterone acetate (ABI) improves survival in mCRPC. In a previous observational study, worse PSA response and shorter progression-free survival (PFS) were associated with mean ABI plasma through concentration (ABI Cmin) < 8.5 ng/mL within the first three months (ms) of treatment (Carton E et al. Eur J Cancer 2017). The OPTIMABI study, a multicenter non-randomized study (NCT 03458247), aimed to investigate whether a dose escalation of ABI improve PFS in underexposed progressive mCRPC pts. Methods: In step 1, pts with docetaxel-naive progressive mCRPC received ABI at the standard dose of 1000 mg/d + Prednisone 10 mg/d. Mean ABI Cmin was calculated from three monthly dosages. Pts experiencing progression within the first 6 ms and for whom mean ABI Cmin was < 8.5 ng/mL were included in step 2 and received 1000 mg twice daily (2000 mg/d) of ABI. ABI Cmin was assessed every month. The primary endpoint was the non-progression rate at 12 weeks in step 2. Identification of risk factors of 6 ms-PFS was done using Cox regression analysis. Results: From 06/2018 to 09/2021, 81 of 93 pts (median age: 72 yrs) included in step 1 were evaluable for statistical analysis. The median ABI Cmin was 10.0 (IQR: 4.5-15. 0) ng/mL over the first three ms. Inter-individual variability was 59%. The 6 ms-PFS was 68% (IC 95%: 56% - 80%) with no statistical difference between pts with mean ABI Cmin ≥ or < 8.5 ng/mL (log-rank test, p= 0.24). In multivariate analysis, liver metastasis (Hazard ratio, HR = 5.95, CI95% = 1.22–28.92; p=0.027) and creatinine clearance < 60 mL/min (HR = 3.51, CI95% = 1.12–10.99; p=0.031) were independently associated with 6 ms-PFS. Among 21 pts (25.9%), with mean ABI Cmin < 8.5 ng/mL, 8 pts (38.1%) experienced tumor progression within the first 6 ms; four of them could be included in step 2. None of them fulfilled the primary endpoint despite a significant increase in plasma ABI Cmin (p <0.036 by paired t-test). Conclusions: Despite high inter-individual variability of mean ABI Cmin, the OPTIMABI study does not support the strategy of intra-individual dose escalation according to plasma concentration of ABI in mCRPC. Underexposure to ABI (ABI Cmin < 8.5 ng/mL) was not statistically associated with shorter PFS. Clinical trial information: NCT03458247 .

Oral EPI-7386 in patients with metastatic castration-resistant prostate cancer.

177 Background: EPI-7386 is a next generation aniten, a novel class of compounds designed to inhibit androgen receptor (AR) activity by binding to the N-terminal domain. Preclinical data supports disruption of AR regulated gene transcription even in the presence of resistance mechanisms including ligand-binding domain point mutations and truncated splice variants. Here we report results of the Part 1a first-in-human trial of EPI-7386 in mCRPC (NCT04421222). Methods: This Phase 1, open-label, multicenter, dose escalation (Part 1a) and expansion (Part 1b) trial was designed to evaluate the safety, pharmacokinetics, pharmacodynamics, and antitumor activity of EPI-7386 in mCRPC patients (pts) progressing on standard of care treatment, including next generation antiandrogen(s) and chemotherapy. Originally designed to assess up to 5 doses of EPI-7386 (200, 400, 600, 800, and 1000 mg QD), two additional cohorts were added examining 400 and 600 mg BID due to 600 mg QD showing exposure saturation while demonstrating a favorable safety profile. Results: 31 pts were enrolled in the QD cohorts and 8 in the BID cohorts. Pts had a median of 4 lines of prior therapy for mCRPC: 83% received abiraterone and at least one next generation AR inhibitor, and 58% had at least one line of prior chemotherapy. No DLTs were observed; EPI-7386 was safe and well tolerated at all doses/schedules evaluated. All related adverse events (AEs) were Grade 1 and 2 and consistent with AEs associated with second-generation antiandrogens. For doses above 400 mg QD, exposures were at or above those associated with antitumor activity in animal models. Evidence of antitumor activity (including significant and durable PSA responses and/or decreases in ctDNA, and/or radiographically documented tumor shrinkage) were observed in pts with fewer than 3 lines of treatment for mCRPC, no visceral metastases and no prior chemotherapy (9/31 pts). Conclusions: Part 1a treatment with EPI-7386 monotherapy was safe, well tolerated up to a daily dose of 1200 mg (600 mg BID), achieved target clinical exposures and showed preliminary signals of antitumor activity in heavily-pretreated mCRPC. Part 1b is open with enrollment focused on pre-chemotherapy, post-second generation antiandrogen treated mCRPC pts in one cohort, and treatment-naïve non-mCRPC pts in a window of opportunity proof-of-concept second cohort. Two doses will be evaluated (600 mg BID and QD) based on FDA Project Optimus recommendations. Clinical trial information: NCT04421222 .

Prognostic Value of Low-Pass Whole Genome Sequencing of Circulating Tumor DNA in Metastatic Castration-Resistant Prostate Cancer.

Multiple treatments are available for metastatic castration-resistant prostate cancer (mCRPC), including androgen receptor signaling inhibitors (ARSI) enzalutamide and abiraterone, but therapy resistance remains a major clinical obstacle. We examined the clinical utility of low-pass whole-genome sequencing (LPWGS) of circulating tumor DNA (ctDNA) for prognostication in mCRPC. A total of 200 plasma samples from 143 mCRPC patients collected at the start of first-line ARSI treatment (baseline) and at treatment termination (n = 57, matched) were analyzed by LPWGS (median: 0.50X) to access ctDNA% and copy number alteration (CNA) patterns. The best confirmed prostate specific antigen (PSA) response (≥50% decline [PSA50]), PSA progression-free survival (PFS), and overall survival (OS) were used as endpoints. For external validation, we used plasma LPWGS data from an independent cohort of 70 mCRPC patients receiving first-line ARSI. Baseline ctDNA% ranged from ≤3.0% to 73% (median: 6.6%) and CNA burden from 0% to 82% (median: 13.1%) in the discovery cohort. High ctDNA% and high CNA burden at baseline was associated with poor PSA50 response (P = 0.0123/0.0081), poor PFS (P < 0.0001), and poor OS (P < 0.0001). ctDNA% and CNA burden was higher at PSA progression than at baseline in 32.7% and 42.3% of the patients. High ctDNA% and high CNA burden at baseline was also associated with poor PFS and OS (P ≤ 0.0272) in the validation cohort. LPWGS of ctDNA provides clinically relevant information about the tumor genome in mCRPC patients. Using LPWGS data, we show that high ctDNA% and CNA burden at baseline is associated with short PFS and OS in 2 independent cohorts.

Salvage vesiculectomy for local prostate cancer recurrence: PSA response and oncological outcomes

Salvage vesiculectomy for local prostate cancer recurrence: PSA response and oncological outcomes

Retrospective Real-world Evaluation of Enzalutamide in Metastatic Hormone Sensitive Prostate Cancer (mHSPC) during the COVID-19 Pandemic Compared to Docetaxel in mHSPC Pre-COVID-19

Purpose: Indirect comparison suggests that androgen receptor targeted agents (ARTA) improve progression free survival and are better tolerated compared to docetaxel in mHSPC [1]. NICE interim guidance during the COVID-19 pandemic allowed the use of ARTA in patients with a new diagnosis of mHSPC instead of docetaxel [2]. In this retrospective observational cohort study, we aimed to assess the use of ARTA as a first line treatment in mHSPC during the COVID-19 pandemic compared to docetaxel pre-COVID-19. The primary endpoint was time to progression (biochemical or radiological). Secondary endpoints included PSA response and adverse event rates. Methods: Patients were identified using the ARIA chemotherapy system as those with mHSPC prescribed first line ARTA between 1 March 2020 and 28 February 2021 compared to patients treated with docetaxel between 1 January 2019 and 31 December 2019. Results: 67 (45 ARTA, 22 docetaxel) eligible patients were identified, with a median overall follow-up of 19 months. The median time to progression was significantly longer in the ARTA group when compared with the docetaxel group (56 weeks versus 48 weeks; P = 0.02). The proportion with a PSA reduction >50% was greater in the ARTA group (97.8% versus 90.9%). The proportion of patients with adverse events leading to dose reduction was lower in the ARTA group (26.7% versus 36.4%) as were the rates of treatment related hospital admission (0% versus 22.7%). Conclusion: These data show that ARTA is better tolerated and associated with a longer progression free survival compared with docetaxel in our patient cohort. These data give further evidence for the efficacy and safety of ARTA and supports their continued use as a first line treatment of mHSPC post-COVID-19 pandemic.

Neutrophil function following treatment of psoriatic arthritis patients with secukinumab: altered cytokine signalling but no impairment of host defence.

Identifying that dysfunction of the IL-23/17 axis underlies PsA has led to the development of effective targeted therapies such as the IL-17A inhibitor secukinumab. As IL-17A stimulates the secretion of neutrophil chemoattractants, such as CXCL8 (IL-8), we examined the effect of secukinumab on neutrophil function in PsA. Nineteen patients with active PsA were treated with secukinumab. Clinical response [PsA Response Criteria (PsARC) and Psoriasis Area and Severity Index (PASI)] and peripheral blood neutrophil function (apoptosis, receptor expression, phagocytosis/killing, chemotaxis and RNA expression) were measured at 12 week intervals for 48 weeks and compared with age- and sex-matched healthy controls. At 12 weeks, 12/16 (75%) patients had a PsARC response (100% at 36 weeks) and 10/14 (71%) achieved a 90% PASI response. At baseline, there were no differences in PsA neutrophil reactive oxygen species generation, constitutive or cytokine-delayed apoptosis, chemotaxis or phagocytosis of opsonized Staphylococcus aureus compared with healthy controls. Similarly, there were no differences in these functions from baseline to 12 weeks of therapy. However, surface levels of CD11b/CD18 and CD63 increased and expression of CD16 decreased during therapy. In addition, in a subgroup of early (12 week) responders to secukinumab, RNA sequencing revealed transcriptome changes predicting down-regulation of cytokine signalling and chemotaxis pathways and up-regulation of de novo gene expression pathways, including translation initiation, mRNA catabolism and translation. Complex changes in the properties of circulating neutrophils occur with secukinumab treatment in PsA that may indicate altered responsiveness to changes in both local and systemic levels of pro-inflammatory cytokines. However, host defence processes of neutrophils were unaltered.

Patient outcomes following a response biomarker-guided approach to treatment using 177Lu-PSMA-I&T in men with metastatic castrate-resistant prostate cancer (Re-SPECT).

177LuPSMA is an effective treatment in metastatic castrate-resistant prostate cancer with trials adopting a standardised dose interval. Adjusting treatment intervals utilising early response biomarkers may improve patient outcomes. This study evaluated progression-free survival (PFS) and overall survival (OS) based on treatment interval adjustment utilising 177LuPSMA 24-h SPECT/CT (177Lu-SPECT) and early prostate-specific antigen (PSA) response. Retrospective analysis of a clinical 177Lu-PSMA-I&T treatment programme. In all, 125 men were treated with 6-weekly 177LuPSMA-I&T [median 3 cycles, interquartile range (IQR): 2-4], median dose 8.0 GBq [95% confidence interval (CI): 7.5-8.0]. Imaging screening involved 68GaPSMA-11 PET/diagnostic CT. 177Lu-SPECT/diagnostic CT was acquired following each therapy, and clinical assessments 3-weekly. Following dose 2 (week 6), a composite PSA and 177Lu-SPECT/CT imaging response [partial response (PR), stable disease (SD), and progressive disease (PD)] determined ongoing management. Response group (RG) 1 (marked reduction in PSA/imaging PR) break in treatment until subsequent PSA rise, then re-treatment. RG 2 (stable or reduced PSA and/or imaging SD) 6-weekly treatments until six doses, or no longer clinically benefitting. RG 3 (rise in PSA and/or imaging PD) recommended for an alternative treatment. Overall PSA50% response rate (PSARR) was 60% (75/125), median PSA-PFS 6.1 months (95%CI: 5.5-6.7), and median OS 16.8 months (95%CI: 13.5-20.1). 35% (41/116) were classified as RG 1, 34% (39/116) RG 2, and 31% (36/116) RG 3. PSARRs by RG were 95% (38/41), 74% (29/39), and 8% (3/36); median PSA-PFS rates were 12.1 months (95%CI: 9.3-17.4), 6.1 months (95%CI: 5.8-9.0), and 2.6 months (95%CI: 1.6-3.1); and OS rates were 19.2 months (95%CI: 16.8-20.7), 13.2 months (95%CI: 12.0-18.8), and 11.2 months (95%CI: 8.7-15.6) for RG 1, 2, and 3, respectively. The median months of 'treatment holiday' for RG 1 was 6.1 months (IQR: 3.4-8.7). Nine men had received prior 177LuPSMA-617 and were retreated with 177LuPSMA-I&T, with a PSARR of 56% on re-treatment. Personalising dosing regimens using early response biomarkers with 177LuPSMA has the potential to achieve similar treatment responses to continuous dosing while allowing treatment breaks or intensification. Further evaluation of early response biomarker-guided treatment regimens in prospective trials is warranted. Lutetium-PSMA therapy is a new therapy for metastatic prostate cancer that is well tolerated and effective. However, not all men respond equally, with some responding very well and others progressing early. Personalising treatments require tools that can accurately measure treatment responses, preferably early in the treatment course, so adjustments to treatment can be made. Lutetium-PSMA can measure tumour sites after each therapy by taking whole body 3D images at 24 h using a small radiation wave from the treatment itself. This is called a SPECT scan. Previous work has shown that both prostate-specific antigen (PSA) response and changes in tumour volume on a SPECT scan can predict how patients will respond to treatment as early as dose 2. This study demonstrates that stratifying how men are treated based on the results of the 6-week SPECT scan and PSA response potentially allows a third of men to have break in treatment and that these men have both longer time to disease progression and OS. Men with an increase in tumour volume and increase in PSA early in treatment (6 weeks) had shorter time to disease progression and OS. Men with early biomarker disease progression were offered alternative treatments early in an attempt to allow the opportunity to allow a more effective potential therapy, if one was available. The study is an analysis of a clinical programme, and was not a prospective trial. As such, there are potential biases that could influence results. Hence, while the study is encouraging for the use of early response biomarkers to guide better treatment decisions, this must be validated in a well-designed clinical trial.

Bipolar androgen therapy plus olaparib in men with metastatic castration-resistant prostate cancer.

Bipolar androgen therapy (BAT) results in rapid fluctuation of testosterone (T) between near-castrate and supraphysiological levels and has shown promise in metastatic castration-resistant prostate cancer (mCRPC). Its clinical effects may be mediated through induction of DNA damage, and preclinical studies suggest synergy with PARP inhibitors. This was a single-center, Phase II trial testing olaparib plus BAT (T cypionate/enanthate 400 mg every 28 days) with ongoing androgen deprivation. Planned recruitment was 30 subjects (equal proportions with/without homologous recombination repair [HRR] gene mutations) with mCRPC post abiraterone and/or enzalutamide. The primary objective was to determine PSA50 response (PSA decline ≥50% from baseline) rate at 12-weeks. The primary analysis utilized the entire (intent-to-treat [ITT]) cohort, with those dropping out early counted as non-responders. Secondary/exploratory analyses were in those treated beyond 12-weeks (response-evaluable cohort). Thirty-six patients enrolled and 6 discontinued prior to response assessment. In the ITT cohort, PSA50 response rate at 12-weeks was 11/36 (31%; 95% CI 17-48%), and 16/36 (44%, 95% CI 28-62%) had a PSA50 response at any time on-study. After a median follow-up of 19 months, the median clinical/radiographic progression-free survival in the ITT cohort was 13.0 months (95% CI 7-17). Clinical outcomes were similar regardless of HRR gene mutational status. BAT plus olaparib is associated with high response rates and long PFS. Clinical benefit was observed regardless of HRR gene mutational status.

This Month in Adult Urology.

This Month in Adult Urology.

Theranostics in prostate cancer

SummaryThis review summarizes current evidence of “theranostics” for patients with prostate cancer. Prostate-specific membrane antigen (PSMA) is a glycoprotein which can be labeled with positron-emitting tomographic (PET) tracers like fluorine-18, gallium-68, or copper-64 and can be labeled with beta emitters like lutetium-177 to treat patients with metastatic castration-resistant prostate cancer (mCRPC). PSMA PET/CT has been shown to be superior to computer tomography (CT) and bone scintigraphy in accuracy, sensitivity, and specificity in the evaluation of metastatic tumor sites and may change treatment management. However, outcome studies showing an improvement in progression-free survival (PFS) and/or overall survival (OS) after management change is missing. PSMA PET/CT is highly recommended in prostate cancer patients with biochemical recurrence (PSA &gt; 0.2 ng/ml). Patients presenting with high PSMA expression in PSMA PET/CT may be favorably treated with 177lutetium-617. In the TheraP study, a multicenter phase 2 trial, patients with mCRPC were randomly assigned to receive either 177lutetium-617 or cabazitaxel. The results indicate fewer treatment-related adverse events in patients treated with 177lutetium-617, an improvement in PSA response, but no improvement in OS after 36 months follow-up. In the VISION trial, a phase 3 international study, patients with mCRPC were randomly assigned to receive either 177lutetium-617 and standard of care (SOC) or SOC alone. At 12 months, radiographic PFS or PSA-PFS was 18% in patients treated with 177lutetium-617 and 3% in patients treated with SOC alone. The real status of 177lutetium-617 in the sequel of treatment regimens remains unclear and additional studies are therefore warranted.

Single Center Experience with a 4-Week 177Lu-PSMA-617 Treatment Interval in Patients with Metastatic Castration-Resistant Prostate Cancer.

177Lu-PSMA-617 is a promising theragnostic treatment for metastatic castration-resistant prostate cancer (mCRPC). However, both the optimal treatment dose and interval in mCRPC and the rate of identification of responders from non-responders among possible treatment candidates are unknown. 62 men with mCRPC who were treated with 177Lu-PSMA-617 during 1/2017-2/2019 were included in the study. Treatment responses, overall survival (OS) and progression free survival (PFS) were determined. The median follow-up time was 1.4 years (IQR 0.5-2.2). Tumor volume of metastases (MTV), SUVmax and tumor lesion activity (TLA) were quantitated from pre-treatment PSMA PET/CT images together with pre-treatment PSA. An average of three treatment cycles (2-5) were given within a four-week interval. PFS was 4.9 months (2.4-9.6) and OS was 17.2 months (6-26.4). There were no major adverse events reported. A significant PSA response of &gt;50% was found in 58.7% of patients, which was significantly associated with longer OS, p &lt; 0.004. PSA response was not associated with staging PSMA-derived parameters. 177Lu-PSMA-617 treatment in four-week intervals was safe and effective. Almost 60% of patients had a significant PSA response, which was associated with better OS. Pre-treatment PSA kinetics or staging PSMA PET/CT-derived parameters were not helpful in identifying treatment responders from non-responders; better biomarkers are needed to aid in patient selection.

Experience of bipolar androgen therapy (BAT) in Argentinian oncology centres.

Previous studies with bipolar androgen therapy (BAT) have shown clinical activity in metastatic Castration Resistant Prostate Cancer (mCRPC) as well as the potential to re-sensitise prostate cancer cells to prior androgen receptor-targeted agents. None of these studies had tested BAT after chemotherapy. In this study, we gathered real-world evidence from three centres in Argentina where BAT is being used in castration-resistant prostate cancer (CRPC), not only prior to chemotherapy but also after several lines of treatment. This retro-prospective nonrandomised multicentre cohort study included patients with mCRPC, who received BAT in different scenarios defined by the treating physician at three centres in Argentina. A total of 21 asymptomatic patients with mCRPC were included. There was a median of two lines before BAT, with nine patients (42.8%) receiving three or more lines, and 13 patients (61.9%) receiving chemotherapy previously. Previous lines included next-generation hormonal agents (NHA) in 100% (abiraterone 33.3% and enzalutamide 71.4%), chemotherapy in 61.9%, Radium-223 in 47.6% and others in 4.8%. The progression free survival (PFS) after BAT was 3.5 months (95% CI: 3.06-7.97). PSA50 response rate (RR) was 28.5% and the overall RR was 14.3%. Of the 17 patients who had disease progression, 9 had a rechallenge to NHA, achieving a 55% RR, 6 received other treatment (chemotherapy in 5 and 177Lu-PSMA in 1) with a 66% RR and 2 best supportive care. The PFS2, calculated after the initiation of BAT in the 15 patients who received further therapy, was 7.93 months (95% CI: 6.73-NR). Treatment was overall well tolerated, with only two patients requiring hospitalisation and treatment interruption due to worsening pain. To the authors' knowledge, this is the first publication of BAT in later lines of therapy in mCRPC. BAT showed clinical activity in this scenario. Our data supports that BAT may play a role in CRPC re-sensitisation after multiple treatment lines.

The Prognostic Significance of Homologous Recombination Repair Pathway Alterations in Metastatic Hormone Sensitive Prostate Cancer.

The homologous recombination repair (HRR) pathway is a frequently mutated pathway in advanced prostate cancer. The clinical course of patients with HRR gene alterations who have metastatic hormone sensitive prostate cancer (mHSPC) has not been fully characterized. Here, we examine the outcomes of men with mHSPC with HRR alterations. We conducted a single-center retrospective analysis of men with mHSPC who underwent next generation sequencing. The primary objective was to assess the time from diagnosis of mHSPC to metastatic castrate resistance prostate cancer (mCRPC) in patients with pathogenic HRR alterations compared to individuals lacking these alterations. Key secondary objectives included time to mCRPC in prespecified cohorts, PSA response, and overall survival. 151 men with mHSPC were identified for the study. 24% (N=37) had pathogenic HRR gene alterations detected with the most common alterations found in BRCA2 (n=15), ATM (n=10), and CDK12 (n=7). Time to mCRPC was significantly decreased in patients with HRR gene alterations versus those without such alterations (12.7 vs. 16.1 months, HR 1.95, P=.02). In multivariate analysis, the effect of HRR gene alterations on time to CRPC remained significant when adjusting for age, mHSPC therapy, the volume of disease, the presence of visceral metastases, and PSA (adjusted HR 1.69, P=.02). Stratified by specific HRR gene alteration, patients with BRCA2 or CDK12 had significantly decreased time to mCRPC compared to other HRR alterations. HRR gene alterations are associated with the worse outcomes in mHSPC with significantly shorter time to mCRPC. Given the established role of Poly (ADP-ribose) Polymerase (PARP) inhibitors in mCRPC, these data highlight an opportunity to examine PARP inhibitors earlier in the clinical course for prostate cancer patients. Ongoing prospective studies will further validate the role of PARP inhibitors in mHSPC patients.

Serum testosterone measured by liquid chromatography-tandem mass spectrometry is an independent predictor of response to castration in metastatic hormone-sensitive prostate cancer

BackgroundAlthough testosterone levels have been associated with progression-free survival (PFS) in metastatic hormone-sensitive prostate cancer (mHSPC) patients, this has primarily been investigated using inaccurate immunoassays (IA). Here, we investigated whether castrate testosterone levels determined by a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay is an independent risk factor for treatment response in mHSPC. MethodsIn total, 106 mHSPC patients treated with luteinizing-hormone releasing-hormone (LHRH) agonists were retrospectively analyzed between March 2018 and August 2021. Testosterone levels in serum samples were quantitated using an LC-MS/MS assay. In a subset of patients, IA (Roche Cobas Pro) values were compared with LC-MS/MS results. Survival analysis was performed using Kaplan-Meier curves and Cox proportional hazard models. ResultsMedian PFS was shorter for high testosterone levels (>0.231 nmol/L, 18.4 v. 42.6 months, HR 1.7, p = 0.018). Low testosterone levels and a PSA response below 4 ng/mL was associated with longer median PFS (46.2 months) than the remaining combinations (13.8–19.3 months, 3.4–5.8, overall p < 0.01). In 67 patients, testosterone levels below the median remained associated with longer PFS, whereas IA measurements did not show a similar difference. ConclusionOur results suggest that high castration testosterone levels measured by LC-MS/MS is an independent response predictor for mHSPC patients.

Effectiveness and durability of benefit of mTOR inhibitors in a real-world cohort of patients with metastatic prostate cancer and PI3K pathway alterations.

Alterations in the PTEN/PI3K/AKT/mTOR pathway are prevalent in prostate cancer. In this retrospective study, we evaluated the clinical effectiveness of mTOR inhibitors (mTORi) in patients with metastatic prostate cancer (mPCA) and tissue assessed phosphatidyl-3-inositol kinase (PI3K) pathway alterations. This study used a nationwide (US-based) de-identified PCA clinico-genomic database, originating from approximately 280 US cancer clinics (~800 sites of care). We evaluated treatment data for patients with PCA from October 2014 to February 2020. In a cohort of 2301 PCA patients with 7208 evaluable treatment lines, we selected 17 mPCA patients (2 hormone-sensitive, 15 castrate-resistant) with tissue assessed PI3K pathway alterations by comprehensive genomic profiling who received mTORi treatment. Patients had a median age of 72 years (IQR 68.0, 76.0) and were heavily pretreated with a median 3 lines of therapy prior to mTORi use (range 0-6). The PI3K pathway alterations included PTENdel (10 patients, 58.8%), AKT1mut (4 patients, 23.5%), PTENmut (2 patients, 11.8%), and dual PTENmut and PIK3CAmut (1 patient, 5.9%). Most (15 patients, 88.2%) were treated with everolimus monotherapy. Among 10 patients with on treatment PSA available, 2 patients had a PSA decrease ≥10% at week 12 and 5 patients overall had a subsequent PSA decrease. For those on mTORi, the median time to next treatment was 3.62 months (range 0, 8.52). In this small cohort of mPCA patients with tissue assessed PI3K pathway alterations, mTORi therapy was not effective with few PSA responses and short duration of therapy.

AlphaBet: Combination of Radium-223 and [17 7Lu]Lu-PSMA-I&T in men with metastatic castration-resistant prostate cancer (clinical trial protocol).

[177Lu]Lu-PSMA is a radioligand therapy used in metastatic castration-resistant prostate cancer (mCRPC). Despite a survival benefit, the responses for many patients receiving [177Lu]Lu-PSMA are not durable, and all patients eventually develop progressive disease. The bone marrow is the most common site of progression. Micrometastases in this area likely receive an inadequate dose of radiation, as the emitted beta-particles from 177Lu travel an average range of 0.7 mm in soft tissue, well beyond the diameter of micrometastases. Radium-223 (223Ra) is a calcium-mimetic and alpha-emitting radionuclide approved for use in men with mCRPC with bone metastases. The range of emitted alpha particles in soft tissue is much shorter (≤100 μm) with high linear energy transfer, likely more lethal for osseous micrometastases. We anticipate that combining a bone-specific alpha-emitter with [177Lu]Lu-PSMA will improve eradication of micrometastatic osseous disease, and thereby lead to higher and longer responses. This is a single-center, single-arm phase I/II trial evaluating the combination of 223Ra and [177Lu]Lu-PSMA-I&T in men with mCRPC. Thirty-six patients will receive 7.4 GBq of [177Lu]Lu-PSMA-I&T, concurrently with 223Ra in escalating doses (28 kBq/kg - 55kBq/kg), both given intravenously every six weeks for up to six cycles. Eligible patients will have at least two untreated bone metastases visible on bone scintigraphy, and PSMA-positive disease on PSMA PET scan. Patients must have adequate bone marrow and organ function and be willing to undergo tumor biopsies. Patients with discordant disease visible on FDG PET scan (defined as FDG positive disease with minimal or no PSMA expression and no uptake on bone scan) will be excluded. Other key exclusion criteria include the presence of diffuse marrow disease, prior treatment with 223Ra or [177Lu]Lu-PSMA, or more than one prior line of chemotherapy for prostate cancer. The co-primary objectives of this study are to determine the maximum tolerated dose of 223Ra when combined with [177Lu]Lu-PSMA-I&T and the 50% PSA response rate. The AlphaBet trial is a phase I/II study combining 223Ra with [177Lu]Lu-PSMA-I&T in patients with mCRPC. We aim to enroll the first patient in Q3 2022, and recruitment is anticipated to continue for 24 months. NCT05383079.