PSA and PSA Kinetics as Predictors for 18F-Fluciclovine PET/CT Positivity in Biochemically Recurrent Prostate Cancer

<b><i>Introduction:</i></b> ¹⁸F-Fluciclovine PET/CT is one of the imaging techniques currently employed to restage prostate cancer (PCa). Due to the conflicting results reported in the literature, it is not yet known at what PSA threshold ¹⁸F-fluciclovine PET/CT could reliably demonstrate the presence of recurring disease. We explored the association between ¹⁸F-fluciclovine PET/CT positivity and prescan PSA, PSA doubling time, and PSA velocity in patients with biochemical recurrence (BCR) of PCa after curative-intent treatment. <b><i>Methods:</i></b> Data from 59 patients who underwent ¹⁸F-fluciclovine PET/CT for BCR after radical prostatectomy or radiotherapy were retrieved from a single institution database. Patients already undergone salvage treatments at the time of PET/CT, with newly diagnosed PCa or with initial diagnosis of metastatic PCa were excluded. A 2-sided independent samples Bayesian <i>t</i> test and Bayesian Mann-Whitney U test were used to assess the association between PET/CT and prescan PSA, PSA doubling time, and PSA velocity. <b><i>Results:</i></b> Evidence for no difference between PET/CT-positive and -negative patients for log-transformed PSA was found (BF₀₁ 3.61, % error: 0.01). Robustness check and sequential analysis showed stability across a wide range of prior distribution specifications. The hypothesis of no difference in terms of PSA-dt and for PSA-vel between groups was found to be more likely compared to the alternative hypothesis (BF₀₁ of 3.44 and 3.48, respectively). <b><i>Conclusion:</i></b> PSA and PSA kinetics are unlikely to be associated with ¹⁸F-fluciclovine PET/CT positivity in patients with BCR, and none of these serum biomarkers might be used as single predictors of PET/CT detection. Larger studies might be needed to evaluate the role of different predictors.

Clinical characteristics and outcomes for patients with non‑metastatic castration-resistant prostate cancer

This study used linked, routinely-collected datasets to explore incidence, clinical characteristics and outcomes of prostate cancer (PC) patients who experience a rise in prostate-specific antigen (PSA) levels despite androgen deprivation therapy (ADT), without evidence of metastases in their patient record, termed non-metastatic castration-resistant PC (nmCRPC). Routinely collected administrative data in Wales were used to identify patients diagnosed with PC and nmCRPC from 2000–2015. Logrank tests and Cox proportional hazard models were used to compare time-to-events across subgroups defined by PSA doubling time and age. Of 38,021 patients identified with PC, 1,465 met nmCRPC criteria. PC incidence increased over the study period, while nmCRPC categorizations reduced. Median time from PC diagnosis to nmCRPC categorization was 3.07 years (95% confidence interval [CI] 2.91–3.26) and from nmCRPC categorization to metastases/death was 2.86 years (95% CI 2.67–3.09). Shorter PSA doubling time (≤ 10 months, versus > 10 months) was associated with reduced time to metastases or death (2.11 years [95% CI 1.92–2.30] versus 5.22 years [95% CI 4.87–5.51]). Age was not significantly associated with time to metastases/death. Our findings highlight key clinical characteristics and outcomes for patients with nmCRPC prior to the introduction of recently approved treatments.

Resolution of the Expert Council on the New Approach to Drug Therapy for Non-Metastatic Castration-Resistant Prostate Cancer

Relevance: Prostate cancer (PC) is one of the most common malignant neoplasms in the male population. The widespread introduction of modern diagnostic methods and the determination of prostate-specific antigen (PSA) levels have increased the number of detected cases of localized and locally advanced PC forms. However, in some patients treated with radical methods and long-term androgen deprivation therapy (ADT), the disease continues to progress in the form of an increase in PSA levels with castration testosterone values and with no distant metastases. Such a course of the disease is referred to as non-metastatic castration-resistant prostate cancer (nmCRPC). Purpose: The article reports the results of a meeting of the Expert Council arranged by the Kazakh Research Institute of Oncology and Radiology on December 25, 2020, on non-metastatic castration-resistant prostate cancer diagnostics and treatment. Results: Large clinical studies highlight the critical importance of controlling the PSA doubling time as the main prognostic factor for an unfavorable outcome to increase patient survival and prevent the development of distant metastases. Based on the results of large randomized studies, experts recommended using new-generation androgen receptor antagonists in combination with ongoing ADT to improve the clinical outcomes in nmCRPC patients at high risk of metastatic progression. The Expert Council was presented with the data of a registration clinical study on darolutamide efficacy and safety. The advantages of introducing this drug into clinical practice to expand the choice of therapeutic options were identified. Personalized adjustment of a treatment regimen will increase the treatment efficacy and ensure higher survival in this category of patients. Conclusion: Increasing survival as the main objective in treating nmCRPC patients requires improved diagnostics through regular controlling of testosterone and PSA levels, calculation of PSA doubling time, and the use of radiological diagnostic methods to rule out distant metastases. The choice of therapy in patients at high risk of metastasis shall consider the patient’s status and the treatment efficacy and safety balance.

Resolution of the Expert Council on the new approach to drug therapy for non-metastatic castration-resistant prostate cancer

Prostate cancer (PC) is one of the most common malignant neoplasms in the male population. The widespread introduction of modern diagnostic methods and the determination of prostate-specific antigen (PSA) levels have increased the number of detected cases of localized and locally advanced PC forms. However, in some patients treated with radical methods and long-term androgen deprivation therapy (ADT), the disease continues to progress in the form of an increase in PSA levels with castration testosterone values and with no distant metastases. Such a course of the disease is referred to as non-metastatic castration-resistant prostate cancer (nmCRPC). Purpose: The article reports the results of a meeting of the Expert Council arranged by the Kazakh Research Institute of Oncology and Radiology on December 25, 2020, on non-metastatic castration-resistant prostate cancer diagnostics and treatment. Results: Large clinical studies highlight the critical importance of controlling the PSA doubling time as the main prognostic factor for an unfavorable outcome to increase patient survival and prevent the development of distant metastases. Based on the results of large randomized studies, experts recommended using new-generation androgen receptor antagonists in combination with ongoing ADT to improve the clinical outcomes in nmCRPC patients at high risk of metastatic progression. The Expert Council was presented with the data of a registration clinical study on darolutamide efficacy and safety. The advantages of introducing this drug into clinical practice to expand the choice of therapeutic options were identified. Personalized adjustment of a treatment regimen will increase the treatment efficacy and ensure higher survival in this category of patients. Conclusion: Increasing survival as the main objective in treating nmCRPC patients requires improved diagnostics through regular controlling of testosterone and PSA levels, calculation of PSA doubling time, and the use of radiological diagnostic methods to rule out distant metastases. The choice of therapy in patients at high risk of metastasis shall consider the patient’s status and the treatment efficacy and safety balance.

Efficacy of androgen receptor antagonists in combination with androgen deprivation therapy in nonmetastatic, castration-resistant prostate cancer: A systematic review and meta-analysis of published phase III randomized controlled trials.

e17606 Background: Nonmetastatic, castration-resistant prostate cancer (nmCRPC) often heralds metastatic disease which is responsible for majority of the morbidity and mortality associated with prostate cancer. Hence, delaying metastasis is an expedient therapeutic goal for the patients with nmCRPC. Three androgen receptor (AR) antagonists — apalutamide, enzalutamide, and darolutamide — have been approved recently for nmCRPC on the basis of prolongation of metastasis-free survival. The purpose of our meta-analysis is to consolidate the efficacy data of AR-antagonists prolonging metastasis-free survival in nmCRPC. Methods: We conducted a systematic search at PUBMED, MEDLINE, EMBASE, and meeting abstracts as per PRISMA guidelines from inception until November 2019. Phase 3 RCTs using AR-antagonists for nmCRPC were included in the final analysis. We used generic inverse variance method and random effects model to calculate the pooled hazard ratio (HR) for distant metastasis or death with 95% confidence interval (CI). Heterogeneity was tested with I2 value and Cochran’s Q test. Results: Three phase 3 RCTs (ARAMIS, PROSPER, and SPARTAN) randomizing 2694 patients in the AR-antagonist arms and 1423 patients in the control arms are included in the final analysis. All studies enrolled only patients with prostate specific antigen (PSA) doubling time of 10 months or less. AR-antagonists used in the study arms were — ARAMIS: darolutamide, PROSPER: enzalutamide, and SPARTAN: apalutamide. Placebo was used in the control arms. All patients continued androgen deprivation therapy (ADT). Randomization was 2:1 in all studies. The pooled HR for distant metastasis or death was highly significant at 0.32 (95% CI: 0.25 - 0.41; P < 0.00001, I2 = 79%) in the favor of AR-antagonist arm in overall population. The pooled HR remained significant when patients were stratified according to PSA doubling time. For patients with PSA doubling time > 6months, the pooled HR was 0.34 (95% CI: 0.27 - 0.43; P < 0.00001, I2 = 0%); for patients with PSA doubling time ≤6 months, the pooled HR was 0.32 (95% CI: 0.25 - 0.41; P < 0.00001, I2 = 73%). Conclusions: Our meta-analysis demonstrated addition of AR-antagonists to ADT significantly prolongs the metastasis-free survival in patients with nmCRPC — an exciting new development in the management of prostate cancer.

A phase IIa randomized placebo-controlled trial of pomegranate fruit extract/POMx in subjects with clinically localized prostate cancer undergoing active surveillance.

285 Background: Due to its high prevalence and often indolent natural history, prostate cancer(PC) active surveillance(AS) is an ideal setting for chemoprevention. Studies assessing pomegranate and its extracts have shown promising anti-proliferative and pro-apoptotic effects in cell lines and animal models and a single-arm clinical trial of pomegranate fruit extract(PFE) reported an increase in PSA doubling time(PSADT) during AS. The primary objective of this trial was to assess the effect of PFE supplementation on plasma levels of Insulin-like Growth Factor-1(IGF-1). Secondary objectives addressed PSA doubling time(PSADT), tumor volume on end-of-study(EOS) biopsy and plasma and prostate tissue biomarkers. Methods: Men with organ-confined favorable-risk PC on AS were randomly assigned to receive PFE 1,000 mg(n=15) or placebo(n=15) once daily for twelve months. Prostate biopsies were performed at study entry and upon completion of the one-year intervention. Tissue biomarkers were assessed by immunohistochemistry(IHC) with automated quantitation. Results: PFE was well-tolerated with no significant toxicities. One patient withdrew before study initiation and 29 completed the one-year intervention. No differences in plasma IGF-1 levels(p=0.5), PSADT, or tissue biomarkers of apoptosis or proliferation were observed. A significant increase in urolithin A(a urinary metabolite of pomegranate) was observed in the PFE arm. IHC analyses of both tumor (Table) and normal-appearing tissue adjacent to tumor showed reductions from baseline in IGF-1, 8-OHdG(DNA damage marker), and androgen receptor expression associated with PFE treatment. A trend towards a reduction in the maximum percent of biopsy core tumor involvement was observed(p=0.06) in PFE. Conclusions: PFE administration for 12-months was not associated with a decrease in plasma IGF-1 levels nor an increase in PSADT. However, exploratory analyses suggest that PFE may contain bioactive compounds capable of altering biomarkers in PC and normal-appearing adjacent tissue providing a rationale for further investigation of PFE in the active surveillance population.