Molecular characterization of prostate cancer in Middle Eastern population highlights differences with Western populations with prognostic implication

Exploring therapeutic applications of PTEN, TMPRSS2:ERG fusion, and tumour molecular subtypes in prostate cancer management

Background

Prostate cancer is defined by the suppression of genes that suppress tumours and the activation of proto-oncogenes. These are the hallmarks of prostate cancer, and they have been linked to numerous genomic variations, which lead to unfavourable treatment outcomes. Prostate cancer can be categorised into various risk groups of tumour molecular subtypes grounded in the idea of genomic structural variations connected to TMPRSS2:ERG fusion and loss of PTEN. Research suggests that certain genomic alterations may be more prevalent or exhibit different patterns in prostate cancer tumours across populations. Studies have reported a higher frequency of PTEN loss and TMPRSS2:ERG fusion in prostate tumours of Black/African American men, which may contribute to the more aggressive nature of the disease in this population. Thus, therapeutically important information can be obtained from these structural variations, including correlations with poor prognosis and disease severity.

Methods

Peer-reviewed articles from 1998 to 2024 were sourced from PubMed and Google Scholar. During the review process, the following search terms were employed: "Tumour suppressor genes OR variations OR alterations OR oncogenes OR diagnostics OR ethnicity OR biomarkers OR prostate cancer genomics OR prostate cancer structural variations OR tumour and molecular subtypes OR therapeutic implications OR immunotherapy OR immunogenetics."

Results

There was a total of 13,012 results for our search query: 5,903 publications from Google Scholar with the patent and citation unchecked filer options, and 7127 articles from PubMed with the abstract, free full text, and full-text options selected. Unpublished works were not involved. Except for four articles published between 1998 and 1999, all other selected articles published in 2000 and later were considered. However, papers with irrelevant information or redundant or duplicate content were not chosen for this review. Thus, 134 met the inclusion criteria and were ultimately retained for this review.

Conclusion

This review extracted 134 relevant articles about genomic structure variations in prostate cancer. Our findings demonstrate the importance of PTEN and TMPRSS2:ERG fusion and tumour molecular subtyping in prostate cancer precision medicine.

Prostate cancer clinical trials in low- and middle-income countries

Background

Prostate cancer is the second most common form of cancer and a leading cause of cancer-related death in men. In an era of evidence-based medicine, clinical trials play a critical role, and adherence to best practices is crucial in managing complicated and non-communicable diseases, such as prostate cancer. For this reason, extrapolating research conducted in high-income countries (HICs) to low-middle-income countries (LMICs) may lead to incorrect findings or treatment plans for patients in these areas. Unfortunately, clinical trials in LMICs face several challenges in terms of design, funding and recruitment. This study aimed to examine clinical trials on prostate cancer in LMICs, including the scope of these trials, the type of interventions being tested and funding sources.

Methods

A search of the Cochrane Library Controlled Trials Registry was conducted between January 2010 and June 2021 using keywords including: 'prostate cancer', 'prostate adenocarcinoma' and 'prostate tumour'). The trials were classified into either HICs or LMICs based on the World Bank Atlas classification. A descriptive analysis was performed to determine the characteristics of the trials.

Results

A total of 3,455 clinical trials for prostate cancer have been conducted globally, with 542 (15.68%) conducted LMICs. Most of these trials (89%) were registered in upper-middle-income countries, with none being conducted in low-income countries. The majority of trials were prospective studies (98.1%), with 65.2% being randomised and 57% being phase III. Of the trials, 48.4% aimed to recruit fewer than 500 participants. The main source of funding was pharmaceutical companies in 78.1% of the cases, followed by institutional funds (16.1%) and public funds (5.8%). At the time of the search query, 74.6% of the trials were inactive, with 37% completed, 5% terminated due to insufficient funding and 75% terminated due to medical inefficacy or poor accrual. The majority of trials (88.2%) were interventional, with only 6% focusing on screening and prevention, and 2% designed for palliative care.

Conclusion

This study sheds light on the challenges faced in conducting clinical trials for prostate cancer in LMICs. The findings underline the need for improved support from international organisations and pharmaceutical companies to bridge the gaps in prostate cancer research and facilitate collaboration between researchers in LMICs and other countries.

Loss of KLK4::KLKP1 pseudogene expression by RNA chromogenic in-situ hybridization is associated with PTEN loss and increased risk of biochemical recurrence in a cohort of middle eastern men with prostate cancer

BACKGROUND

KLK4::KLKP1 fusion is a recently described pseudogene that is enriched in prostate cancer (PCa). This new biomarker has not been characterized in the Middle Eastern population.

OBJECTIVE

To establish the incidence and prognostic value of KLK4::KLKP1 fusion in a cohort of Middle Eastern men with PCa and explore the relationship of this marker to other relevant biomarkers (PTEN, ERG, SPINK1).

DESIGN, SETTING, AND PARTICIPANTS

We interrogated a cohort of 340 Middle Eastern men with localized PCa treated by radical prostatectomy between 2005 and 2015. KLK4::KLKP1 fusion status was assessed by RNA Chromogenic in situ hybridization (CISH) and correlated to pathological and clinical parameters.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

RNA-CISH expression of KLK4::KLKP1 was correlated with prognostic factors, ERG, PTEN, and SPINK1 expression, and biochemical recurrence (BCR) following prostatectomy.

RESULTS AND LIMITATIONS

51.7% of patient samples showed positive KLK4::KLKP1 expression; more commonly in cores of PCa (38%) versus non-cancer (20.6%) (p < 0.0001) and in lower Gleason Grade Group tumors (1-3) vs (4-5). KLK4::KLKP1 expression positively correlated with ERG positivity and inversely associated with PTEN loss. No significant association was found with SPINK1 expression, seminal vesicle invasion, positive surgical margin, pathological stage, or patient age (< 50 or ≥ 50). The association between PTEN loss and BCR increased when combined with KLK4::KLKP1 negativity (HR 2.31, CI 1.03-5.20, p = 0.042).

CONCLUSIONS

KLK4::KLKP1 expression is more common in this cohort of Middle Eastern men than has been reported in North American men. It is associated with ERG positivity and inversely correlated with PTEN loss. In isolation, KLK4::KLKP1 expression was not significantly associated with clinical outcome or pathological parameters. However, its expression is associated with certain molecular subtypes (ERG-positive, PTEN-intact) and as we demonstrate may help further stratify the risk of recurrence within these groups.

Copy Number Profiles of Prostate Cancer in Men of Middle Eastern Ancestry

Simple Summary

Prostate cancer is the most commonly diagnosed non-skin malignancy in men. Numerous studies have been undertaken to explore the role that genomics plays in prostate cancer initiation and progression. Most of this genomic data comes tumors arising in men with European or Asian ancestry, leaving other ancestry groups understudied. To fill this gap, we investigated the differences in copy number aberrations between prostate cancers arising in men of Middle Eastern ethnicity and those of European, African, or East Asian ethnicities in the hope of better understanding the incidence and risk of prostate cancer in different populations. We identified ancestry-specific gains and deletions, as well as differences in overall genomic instability between ancestry groups. This confirms that ancestry should be considered when investigating and characterizing biomarkers and molecular signatures relative to disease progression, prognosis, and potentially therapeutic targeting.

Abstract

Our knowledge of prostate cancer (PCa) genomics mainly reflects European (EUR) and Asian (ASN) populations. Our understanding of the influence of Middle Eastern (ME) and African (AFR) ancestry on the mutational profiles of prostate cancer is limited. To characterize genomic differences between ME, EUR, ASN, and AFR ancestry, fluorescent in situ hybridization (FISH) studies for NKX3-1 deletion and MYC amplification were carried out on 42 tumors arising in individuals of ME ancestry. These were supplemented by analysis of genome-wide copy number profiles of 401 tumors of all ancestries. FISH results of NKX3-1 and MYC were assessed in the ME cohort and compared to other ancestries. Gene level copy number aberrations (CNAs) for each sample were statistically compared between ancestry groups. NKX3-1 deletions by FISH were observed in 17/42 (17.5%) prostate tumors arising in men of ME ancestry, while MYC amplifications were only observed in 1/42 (2.3%). Using CNAs called from arrays, the incidence of NKX3-1 deletions was significantly lower in ME vs. other ancestries (20% vs. 52%; p = 2.3 × 10⁻³). Across the genome, tumors arising in men of ME ancestry had fewer CNAs than those in men of other ancestries (p = 0.014). Additionally, the somatic amplification of 21 specific genes was more frequent in tumors arising in men of ME vs. EUR ancestry (two-sided proportion test; Q < 0.05). Those included amplifications in the glutathione S-transferase family on chromosome 1 (GSTM1, GSTM2, GSTM5) and the IQ motif-containing family on chromosome 3 (IQCF1, IQCF2, IQCF13, IQCF4, IQCF5, IQCF6). Larger studies investigating ME populations are warranted to confirm these observations.

Primary metastatic prostate cancer between prognosis or adequate/proper medical therapy

Purpose

To define the efficacy of standard androgen deprivation therapy (ADT) in the treatment of metastatic prostate cancer (PCa).

Materials and methods

Fifty patients with mean age of 70.48 ± 9.95 years old (range 52–87) who had metastatic PCa and received ADT between 2014 and 2019 were retrospectively evaluated. Median values of pre-therapeutic PSA and Gleason scores were 50 ng/ml (range 8–1201) and 8 (range 6–9), respectively. All patients received luteinizing hormone-releasing hormone (LHRH) analogue and anti-androgen. The patients were evaluated in terms of age, pre-therapeutic PSA serum levels, Gleason scores, presence of metastasis, number and percentage of cores involved, nadir PSA, time to nadir PSA, duration of ADT, and PSA at last follow-up. Multivariate analysis was used to define the factors which have impact on ADT response. The mean follow-up period was 13.87 ± 7.78 months, (range 2–32).

Results

All patients showed reduction in serum PSA level after initiation of ADT, and the median value of nadir PSA was 1.12 ng/ml (range 0.02–50). The mean value of time to nadir PSA was 3.85 ± 1.57 months (range 2–7). The median value of PSA at last follow-up was 2 ng/ml (range 0.02–50.21). Multi-variant analysis showed that nadir PSA have a significant correlation with pre-therapeutic PSA, PSA at last follow-up, age, and Gleason scores (p < .05).

Conclusion

Standard ADT is a feasible option in the treatment of metastatic PCa. Gleason scores, age, pre-therapeutic PSA, and PSA at last follow-up have significant impact on outcomes of ADT. Further studies of high number of patients with long-term follow-up including other chemo-hormonal therapy and androgen receptor blockers should be carried out to confirm and improve efficacy of ADT.