Management of advanced prostate cancer in a middle-income country: real-world consideration of the Advanced Prostate Cancer Consensus Conference 2017

TAS3681, an androgen receptor antagonist, prevents drug resistance driven by aberrant androgen receptor signaling in prostate cancer

Second-generation androgen receptor (AR) signaling inhibitors (ARSIs), such as abiraterone and enzalutamide, prolong the life of patients with castration-resistant prostate cancer (CRPC). However, patients receiving ARSIs ultimately develop resistance through various complex mechanisms, including AR mutations, constitutively active AR-splice variants (AR-Vs), and AR overexpression. Here, we characterized a novel AR pure antagonist, TAS3681, which inhibits AR transcriptional activity and downregulates AR-full length (AR-FL) and AR-Vs. TAS3681 reduced the protein levels of AR-FL and AR-Vs including AR-V7 in enzalutamide-resistant cells (SAS MDV No. 3-14), in vitro and in vivo, showing strong antitumor efficacy in an AR-V7-positive xenograft model. In AR-overexpressing VCaP (prostate cancer) cells, conversely to enzalutamide, TAS3681 effectively suppressed cell proliferation and downregulated AR expression. Importantly, TAS3681 blocked the transcriptional activity of various mutant ARs, including mutations F877L/T878A and H875Y/T878A, which confer resistance to enzalutamide, and V716M and H875Y mutations, which confer resistance to darolutamide. Our results demonstrate that TAS3681 suppresses the reactivation of AR signaling, which causes resistance to ARSIs, via a newly identified mechanism of action. Therefore, TAS3681 could be a new therapeutic option for CRPC treatment.

Prostate cancer management in Southeast Asian countries: a survey of clinical practice patterns

Background

Prostate cancer (PC) has a serious public health impact, and its incidence is rising due to the aging population. There is limited evidence and consensus to guide the management of PC in Southeast Asia (SEA). We present real-world data on clinical practice patterns in SEA for advanced PC care.

Method

A paper-based survey was used to identify clinical practice patterns and obtain consensus among the panelists. The survey included the demographics of the panelists, the use of clinical guidelines, and clinical practice patterns in the management of advanced PC in SEA.

Results

Most panelists (81%) voted prostate-specific antigen (PSA) as the most effective test for early PC diagnosis and risk stratification. Nearly 44% of panelists agreed that prostate-specific membrane antigen positron emission tomography-computed tomography imaging for PC diagnostic and staging information aids local and systemic therapy decisions. The majority of the panel preferred abiraterone acetate (67%) or docetaxel (44%) as first-line therapy for symptomatic mCRPC patients. Abiraterone acetate (50%) is preferred over docetaxel as a first-line treatment in metastatic castration-sensitive prostate cancer patients with high-volume disease. However, the panel did not support the use of abiraterone acetate in non-metastatic castration-resistant prostate cancer (nmCRPC) patients. Apalutamide (75%) is the preferred treatment option for patients with nmCRPC. The cost and availability of modern treatments and technologies are important factors influencing therapeutic decisions. All panelists supported the use of generic versions of approved therapies.

Conclusion

The survey results reflect real-world management of advanced PC in a SEA country. These findings could be used to guide local clinical practices and highlight the financial challenges of modern healthcare.

Burden of prostate cancer in the Middle East: A comparative analysis based on global cancer observatory data

BACKGROUND

Prostate cancer represents a significant global health issue, yet our understanding of its impact in the Middle East remains limited. This study aimed to assess the incidence and mortality of prostate cancer in the Middle East, and compare these rates to those in Europe and North America.

MATERIALS AND METHODS

We utilized the 2020 Global Cancer Observatory data, compiling incidence and mortality rates of prostate cancer in 20 Middle Eastern countries. We calculated mortality-to-incidence ratios (MIR) and compared the age-standardized incidence rate (ASIR) and MIR between the Middle East and the combined regions of North America and Europe. The countries were further stratified based on the Human Development Index (HDI) and income level for additional analysis.

RESULTS

In 2020, the Middle East documented an estimated 51,649 new prostate cancer diagnoses, accounting for 3.7% of global cases. Despite a significantly lower ASIR in the Middle East compared with Europe and North America (10.50 vs. 21.50, p = 0.0087), the region had a higher MIR (12.35 vs. 3.00, p = 0.0476). When stratified based on HDI or income levels, there was no significant difference in MIRs; however, a significant trend of increasing MIR with decreasing HDI (p = 0.028) and income levels (p = 0.016) was observed.

CONCLUSIONS

Despite a lower incidence, our analysis showed a significantly higher MIR for prostate cancer in the Middle East compared with Europe and North America. These findings underscore the unique challenges posed by prostate cancer in the Middle East and emphasize the necessity of tailored strategies to address this pressing public health issue.

Darolutamide for non-metastatic castration-resistant prostate cancer: Efficacy, safety, and clinical perspectives of use

Darolutamide, a second-generation androgen receptor inhibitor (SGARI), has been shown to increase metastasis-free survival and overall survival among men with non-metastatic castration-resistant prostate cancer (nmCRPC). Its unique chemical structure potentially provides efficacy and safety advantages over the SGARIs apalutamide and enzalutamide, which are also indicated for nmCRPC. Despite a lack of direct comparisons, the SGARIs appear to have similar efficacy, safety, and quality of life (QoL) results. Indirect evidence suggests that darolutamide is preferred for its good adverse event profile, an attribute valued by physicians, patients, and their caregivers for maintaining QoL. Darolutamide and others in its class are costly; access may be a challenge for many patients and may lead to modifications to guideline-recommended regimens.

Prostate cancer in multi-ethnic Asian men: Real-world experience in the Malaysia Prostate Cancer (M-CaP) Study

Prostate cancer is the third most common cancer in Malaysia with the lifetime risk of 1 in 117 men. Here, we initiated a longitudinal Malaysia Prostate Cancer (M‐CaP) Study to investigate the clinical and tumour characteristics, treatment patterns as well as disease outcomes of multi‐ethnic Asian men at real‐world setting. The M‐CaP database consisted of 1839 new patients with prostate cancer diagnosed between 2016 and 2018 from nine public urology referral centres across Malaysia. Basic demographic and clinical parameters, tumour characteristics, primary treatment, follow‐up and vital status data were retrieved prospectively from the hospital‐based patients’ case notes or electronic medical records. Primary endpoints were overall survival (OS) and biochemical progression‐free survival (bPFS). The median age at diagnosis of M‐CaP patients was 70 years (interquartile range, IQR 65–75). Majority of patients were Chinese (831, 45.2%), followed by Malays (704, 38.3%), Indians (124, 6.7%) and other races (181, 9.8%). The median follow‐up for all patients was 23.5 months (IQR 15.9–33.6). Although 58.1% presented with late‐stage cancer, we observed ethnic and geographic disparities in late‐stage prostate cancer diagnosis. Curative radiotherapy and primary androgen deprivation therapy were the most common treatment for stage III and stage IV diseases, respectively. The median OS and bPFS of stage IV patients were 40.1 months and 19.2 months (95% CI 17.6–20.8), respectively. Late stage at presentation remains a challenge in multi‐ethnic Asian men. Early detection is imperative to improve treatment outcome and survival of patients with prostate cancer.

Recent trend of androgen deprivation therapy in newly diagnosed prostate cancer patients: Comparing between high- and middle-income Asian countries

The number of newly diagnosed prostate cancer cases varies across Asia, with higher mortality‐to‐incidence ratio reported in developing nations. Androgen deprivation therapy (ADT), alone or in combination, remains the mainstay of first‐line treatment for advanced prostate cancer. Key findings of extensive research and randomized controlled trials have shaped current clinical practice and influenced clinical guideline recommendations. We describe here the recent trend of ADT in newly diagnosed prostate cancer for Asia focusing on Japan (high‐income country) and Malaysia (middle‐income country) based on the Asian Prostate Cancer (A‐CaP) Study. The combination of radiotherapy and ADT or ADT alone was common in patients with intermediate‐to‐high risk localized and locally advanced disease. For metastatic prostate cancer, maximum androgen blockade (gonadotrophin‐releasing hormone [GnRH] agonist/antagonist plus antiandrogen) was prevalent among the Japanese patients while primary ADT alone with GnRH agonist/antagonist was widely practiced in the Malaysian cohort. Upfront combined therapy (ADT plus docetaxel or androgen receptor pathway inhibitor) has significantly improved the outcomes of patients with metastatic castration‐naïve prostate cancer. Its application, however, remains low in our cohorts due to patients’ financial capacity and national health insurance coverage. Early detection remains the cornerstone in prostate cancer control to improve treatment outcome and patient survival.

Modified J-CAPRA scoring system in predicting treatment outcomes of metastatic prostate cancer patients undergoing androgen deprivation therapy

The J‐CAPRA score is an assessment tool which stratifies risk and predicts outcome of primary androgen deprivation therapy (ADT) using prostate‐specific antigen, Gleason score, and clinical TNM staging. Here, we aimed to assess the generalisability of this tool in multi‐ethnic Asians. Performance of J‐CAPRA was evaluated in 782 Malaysian and 16,946 Japanese patients undergoing ADT from the Malaysian Study Group of Prostate Cancer (M‐CaP) and Japan Study Group of Prostate Cancer (J‐CaP) databases, respectively. Using the original J‐CAPRA, 69.6% metastatic (M1) cases without T and/or N staging were stratified as intermediate‐risk disease in the M‐CaP database. To address this, we first omitted clinical T and N stage variables, and calculated the score on a 0–8 scale in the modified J‐CAPRA scoring system for M1 patients. Notably, treatment decisions of M1 cases were not directly affected by both T and N staging. The J‐CAPRA score threshold was adjusted for intermediate (modified J‐CAPRA score 3–5) and high‐risk (modified J‐CAPRA score ≥6) groups in M1 patients. Using J‐CaP database, validation analysis showed that overall survival, prostate cancer‐specific survival, and progression‐free survival of modified intermediate and high‐risk groups were comparable to those of original J‐CAPRA (p > 0.05) with Cohen's coefficient of 0.65. Around 88% M1 cases from M‐CaP database were reclassified into high‐risk category. Modified J‐CAPRA scoring system is instrumental in risk assessment and treatment outcome prediction for M1 patients without T and/or N staging.

Clinical outcomes of abiraterone acetate and predictors of its treatment duration in metastatic castration-resistant prostate cancer: Real-world experience in the Southeast Asian cohort

It is of much interest to understand the efficacy of abiraterone acetate (AA) in routine clinical practice. We assessed the clinical outcome of AA in patients with metastatic castration-resistant prostate cancer (mCRPC) and determined clinical factors associated with AA treatment duration in real-world setting. This real-world cohort consisted of 93 patients with mCRPC treated with AA in Thailand (58.1%) and Malaysia (41.9%). Primary endpoints were overall survival (OS) and biochemical progression-free survival (bPFS). Secondary endpoints were predictors associated with AA treatment duration evaluated with Cox proportional hazards regression. Around 74% were chemotherapy-naïve. The median AA treatment duration was 10 months (IQR 5.6-17.1). Malaysians had a relatively lower median OS and bPFS (OS 17.8 months; 95% CI 6.4-29.1, bPFS 10.4 months; 95% CI 8.8-12.0) compared to Thais (OS 27.0 months; 95% CI 11.3-42.7, bPFS 14.0 months; 95% CI 5.8-22.2), although it did not achieve statistical significance (P > .05). Patients with longer AA treatment duration (>10 months) had lower risk of death and longer bPFS, compared to those with shorter AA treatment duration (≤10 months) (hazard ratio [HR] 0.10, 95% CI 0.05-0.22 and HR 0.13, 95% CI 0.06-0.25, respectively). Multivariable analysis showed that PSA at AA initiation, presence of PSA response and chemotherapy-naive were independently associated with AA duration (P < .05). Abiraterone acetate is well-tolerated in the Southeast Asian cohort with comparable survival benefits to other Asian populations in real-world setting. Lower PSA levels at AA initiation, presence of PSA response, and chemotherapy-naive were significant in determining AA treatment duration.

Preclinical profile and phase I clinical trial of a novel androgen receptor antagonist GT0918 in castration-resistant prostate cancer

PURPOSE

We conducted preclinical experiments and phase I clinical trial to investigate the safety, pharmacokinetics (PK) and antitumour effects of GT0918 in castration-resistant prostate cancer (CRPC).

EXPERIMENTAL DESIGN

An androgen receptor (AR) competitive binding assay was performed, followed by evaluation of GT0918 on AR protein expression. The efficacy of GT0918 was investigated in a castration-resistant xenograft model. A phase I dose-escalation study of GT0918 in CRPC was also carried out to evaluate its safety, PK and antitumour efficacy.

RESULTS

GT0918 was demonstrated to inhibit the binding of androgen to AR more potently than MDV3100, and to effectively reduce the AR protein level. GT0918 inhibited the transcriptional activity of wild-type AR and AR with clinically relevant ligand-binding domain mutations. Furthermore, GT0918 significantly inhibited the growth of prostate cancer. A total of 16 patients was treated with GT0918 at five dose levels. Among these 16 patients, 10 and 2 patients, respectively, completed a three-cycle and six-cycle treatment, in which MTD was not reached. All the treatment-related adverse events were grade I, including hypercholesterolemia, hypertriglyceridemia, fatigue and anaemia. PK parameters showed that drug exposure increased with dose proportionally from 50 to 300 mg and a saturation was observed between 300 and 400 mg. PSA declines of ≥30% and ≥50% were, respectively, observed in six and two cases. All the 12 patients with metastatic soft tissue lesions confirmed stable disease.

CONCLUSIONS

GT0918, a full AR antagonist without agonist effect, has high binding affinity to AR with AR protein down-regulation activity. GT0918 is demonstrated to be well tolerated with a favourable PK profile and exhibits promising antitumour activity in CRPC. CLINICALTRIALS: gov identifier CTR20150501.

Management of Advanced and Metastatic Prostate Cancer: A Need for a Sub-Saharan Guideline

The estimated incidence rate of prostate cancer in Africa was 22.0/100,000 in 2016. The International Agency for Research on Cancer (IARC) has cited prostate cancer as a growing health threat in Africa with approximated 28,006 deaths in 2010 and estimated 57,048 deaths in 2030. The exact incidence of advanced and metastatic prostate cancer is not known in sub-Saharan Africa. Hospital-based reports from the region have shown a rising trend with most patients presenting with advanced or metastatic disease. The management of advanced and metastatic prostate cancer is challenging. The available international guidelines may not be cost-effective for an African population. The most efficient approach in the region has been surgical castration by bilateral orchidectomy or pulpectomy. Medical androgen deprivation therapy is expensive and may not be available. Patients with metastatic castrate-resistant prostate cancer tend to be palliated due to the absence or cost of chemotherapy or second-line androgen deprivation therapy in most of Africa. A cost-effective guideline for developing nations to address the rising burden of advanced prostate cancer is warranted at this moment.