Alterations in homologous recombination repair genes in prostate cancer brain metastases

Incidental Brain Metastases From Prostate Cancer Diagnosed With PSMA PET/CT and MRI: A Case Series and Literature Review

BACKGROUND

Brain metastases (BMETS) from prostate cancer are rare. Hence, brain imaging in neurologically asymptomatic patients with advanced prostate cancer (aPC) is not routinely performed. Prostate-specific membrane antigen (PSMA) PET/CT uses a radiotracer that binds to prostate cancer epithelial cells and is FDA-approved for initial staging for high-risk prostate cancer, detecting prostate cancer recurrence, and determining eligibility for radionuclide therapy.

METHODS

We report six patients with asymptomatic BMETS from aPC found on staging PSMA PET/CT or MRI. Along with cranial MRI, PSMA PET/CT may be useful for detecting asymptomatic intracranial metastasis in select patients with prostate cancer.

RESULTS

Brain metastases were diagnosed in four patients by staging PSMA PET/CT scan-three after systemic disease progression and one during routine surveillance. In two other patients, BMETS were detected using MRI despite negative PSMA PET/CT for brain lesions. All were neurologically asymptomatic. Three patients had undetectable serum prostate-specific antigen (PSA) concentrations; one had neuroendocrine differentiation on histology.

CONCLUSION

In patients with poorly differentiated or neuroendocrine aPC, BMETS may occur without neurologic symptoms and stable PSA. PSMA PET/CT may complement brain MRI for identifying BMETS in these patients.

Key considerations for a prostate cancer mRNA vaccine

Prostate cancer has the second highest cancer mortality rate in the UK in males. Early prostate cancer is typically asymptomatic, with diagnosis at a locally advanced or metastatic stage. In addition, the inherent heterogeneity of prostate cancer tumours differs significantly in terms of genetic, molecular, and histological features. The successful treatment of prostate cancer is therefore exceedingly challenging. Immunotherapies, particularly therapeutic vaccines, have been widely used in preclinical and clinical studies to treat various cancers. Sipuleucel-T was the first cancer vaccine approved by the FDA for the treatment of asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC), ushering in a new era of immunotherapy. In this review, the latest immunotherapy strategies for prostate cancer are considered with key tumour-associated antigens (TAA) and tumour-specific antigens (TSA) highlighted. The key components of mRNA vaccines include in vitro transcription, stability, and immunogenicity. Finally, strategies to circumvent in vivo mRNA degradation and approaches to optimise in vitro transcription (IVT) process are also discussed.

Identification and Validation of Alkaliptosis Resistance-Associated Genes in Prostate Cancer Via Transcriptome Sequencing and Prediction of Biochemical Recurrence

Androgen deprivation therapy (ADT) is the primary treatment strategy for prostate cancer. However, despite an initially favorable response, tumors inevitably progress to castration-resistant prostate cancer (CRPC). Therefore, the exploration of new therapeutic approaches targeting CRPC has become imperative. Increasing evidence suggests that hypoxia plays a crucial role in the development of CRPC. In this study, we found that the emergence of alkaliptosis resistance and the expression of its marker, CA9, significantly contribute to the progression of castration resistance induced by hypoxia. This study utilized bioinformatics approaches to identify genetic determinants associated with alkaliptosis resistance and explored the clinical significance of these marker genes. Transcriptomic sequencing was performed on the DU145 prostate cancer cell line, which had been induced to acquire alkaliptosis resistance. Using least absolute shrinkage and selection operator (LASSO) regression analysis, a prognostic risk model consisting of 12 genes, including ADORA2A, KCNG4, SEC14L5, B3GAT2, SLFNL1, FAM72D, CBWD3, PPM1K, STARD4, DEPDC1B, MATN3, and DDIAS was developed. The risk model score demonstrated a strong correlation with key patient clinical characteristics, including Gleason score, PSA levels, T stage, and N stage, and was also associated with immune therapy response and biochemical recurrence-free survival (BCRFS). Furthermore, ADORA2A expression in cellular models was found to be a critical factor in promoting alkaliptosis resistance.

Integrated multi-omics assessment of lineage plasticity in a prostate cancer patient with brain and dural metastases

Metastases to the brain are rare in prostate cancer. Here, we describe a patient with two treatment-emergent metastatic lesions, one to the brain with neuroendocrine prostate cancer (NEPC) histology and one to the dural membrane of adenocarcinoma histology. We performed genomic, transcriptomic, and proteomic characterization of these lesions and the primary tumor to investigate molecular features promoting these metastases. The two metastatic lesions had high genomic similarity, including TP53 mutation and PTEN deletion, with the most striking difference being the additional loss of RB1 in the NEPC lesion. Interestingly, the dural lesion expressed both androgen receptor and neuroendocrine markers, suggesting amphicrine carcinoma (AMPC). When analyzing pioneer transcription factors, the AMPC lesion exhibited elevated FOXA1 activity while the brain NEPC lesion showed elevated HOXC10, NFYB, and OTX2 expression suggesting novel roles in NEPC formation or brain tropism. Our results highlight the utility of performing multi-omic characterization, especially in rare cancer subtypes.

Brain Metastatic Prostate Adenocarcinoma: Avoiding Mistaken Identities

Brain metastatic carcinoma is a rare occurrence among prostate cancer metastases. 68Gallium prostate-specific membrane antigen PET-CT ([68Ga]PSMA PET/CT) is commonly used for prostate cancer staging and detection of biochemical recurrences. However, various CNS tumors exhibit activity on [68Ga]PSMA PET/CT and may often be included in the differential diagnosis. Herein, we present a case of brain metastatic prostate cancer successfully treated with surgical resection and adjuvant stereotactic Gamma Knife radiosurgery (GKRS) followed by androgen deprivation therapy (ADT) to emphasize the need for histologic confirmation. A 70-year-old male with a history of very high-risk prostatic adenocarcinoma presented with biochemical recurrence following radical prostatectomy and irradiation of the prostatic fossa. [68Ga]PSMA PET/CT and MRI identified a solitary lesion in the left occipital lobe; differential diagnosis included prostate metastasis, meningioma, or a new metastatic primary lesion. The patient underwent surgical resection, and immunohistochemical staining confirmed the lesion as brain metastatic prostate adenocarcinoma. One month after resection, the patient underwent GKRS to the tumor bed and two additional metastases, followed by ADT. Repeated imaging 15 months after GKRS revealed stable posttreatment changes with no evidence of new metastases, thus demonstrating durable, effective local and systemic control. Brain metastatic prostate adenocarcinoma without nodal or osseous metastases is a rare phenomenon. The affinity of [68Ga]PSMA PET/CT for non-prostate histologies such as meningioma introduces uncertainty into the diagnostic process. This case demonstrates the durable local control conferred by GKRS toward these lesions and emphasizes the need for clinical, radiographic, and histopathologic data to identify disease presentations and facilitate appropriate treatment regimens.

Identification of recurrent BRAF non-V600 mutations in intraductal carcinoma of the prostate in Chinese populations

While BRAF alterations have been established as a driver in various solid malignancies, the characterization of BRAF alterations in prostate cancer (PCa) has not been thoroughly interrogated. By bioinformatics analysis, we first found that BRAF alterations were associated with advanced PCa and exhibited mutually exclusive pattern with ERG alteration across multiple cohorts. Of the most interest, recurrent non-V600 BRAF mutations were found in 3 of 21 (14.3 %) PCa patients demonstrating IDC-P morphology. Furthermore, experimental overexpression of BRAFK601E and BRAFL597R exhibited emergence of oncogenic phenotypes with intensified MAPK signaling in vitro, which could be targeted by MEK inhibitors. Comparison of the incidence of BRAF alterations in IDC-P between western and Chinese ancestry revealed an increased prevalence in the Chinese population. The BRAF mutation may represent important genetic alteration in a subset of IDC-P, highlighting the role of MAPK signaling pathway in this subtype of PCa. To the best of knowledge, this is the first description of non-V600 BRAF mutation in setting of IDC-P, which may in part explain the aggressive phenotype seen in IDC-P and could also bring more treatment options for PCa patients with IDC-P harboring such mutations.

DNA Damage Response and Mismatch Repair Gene Defects in Advanced and Metastatic Prostate Cancer

Alterations in DNA damage response (DDR) and related genes are present in up to 25% of advanced prostate cancers (PCa). Most frequently altered genes are involved in the homologous recombination repair, the Fanconi anemia, and the mismatch repair pathways, and their deficiencies lead to a highly heterogeneous spectrum of DDR-deficient phenotypes. More than half of these alterations concern non- BRCA DDR genes. From a therapeutic perspective, poly-ADP-ribose polymerase inhibitors have demonstrated robust clinical efficacy in tumors with BRCA2 and BRCA1 alterations. Mismatch repair-deficient PCa, and a subset of CDK12-deficient PCa, are vulnerable to immune checkpoint inhibitors. Emerging data point to the efficacy of ATR inhibitors in PCa with ATM deficiencies. Still, therapeutic implications are insufficiently clarified for most of the non- BRCA DDR alterations, and no successful targeted treatment options have been established.

Diplopia and Ptosis: An Unusual Case of Prostate Cancer Metastasis to the Sphenoid Bone Treated With Palliative Radiotherapy

We report a case of a 72-year-old male who presented to the hospital with a chief complaint of diplopia in the setting of a recent onset of urinary incontinence and right-sided back pain. He was subsequently diagnosed with prostate cancer, notably metastasizing to the right sphenoid bone, causing impingement of the oculomotor nerve. Our case is unique in that the patient's initial presentation of prostate cancer was oculomotor nerve palsy with subsequent histologic analysis of the primary tumor showing both small cell neuroendocrine carcinoma along with adenocarcinoma. Also, the initial routine stroke protocol MRI and computed tomography angiography (CTA) missed the lesion, while gadolinium-enhanced targeted MRI revealed lesions in both the spine and the orbit. This case emphasizes the need for enhanced contrast as well as focused imaging in patients presenting with diplopia with a negative initial workup for stroke. Ptosis can be a sign of metastasis from other cancers and it is important to have a broad differential including metastatic disease in patients' presenting with similar symptoms and negative initial workup who may otherwise be at risk of cancer.

Evolution of structural rearrangements in prostate cancer intracranial metastases

Intracranial metastases in prostate cancer are uncommon but clinically aggressive. A detailed molecular characterization of prostate cancer intracranial metastases would improve our understanding of their pathogenesis and the search for new treatment strategies. We evaluated the clinical and molecular characteristics of 36 patients with metastatic prostate cancer to either the dura or brain parenchyma. We performed whole genome sequencing (WGS) of 10 intracranial prostate cancer metastases, as well as WGS of primary prostate tumors from men who later developed metastatic disease (n = 6) and nonbrain prostate cancer metastases (n = 36). This first whole genome sequencing study of prostate intracranial metastases led to several new insights. First, there was a higher diversity of complex structural alterations in prostate cancer intracranial metastases compared to primary tumor tissues. Chromothripsis and chromoplexy events seemed to dominate, yet there were few enrichments of specific categories of structural variants compared with non-brain metastases. Second, aberrations involving the AR gene, including AR enhancer gain were observed in 7/10 (70%) of intracranial metastases, as well as recurrent loss of function aberrations involving TP53 in 8/10 (80%), RB1 in 2/10 (20%), BRCA2 in 2/10 (20%), and activation of the PI3K/AKT/PTEN pathway in 8/10 (80%). These alterations were frequently present in tumor tissues from other sites of disease obtained concurrently or sequentially from the same individuals. Third, clonality analysis points to genomic factors and evolutionary bottlenecks that contribute to metastatic spread in patients with prostate cancer. These results describe the aggressive molecular features underlying intracranial metastasis that may inform future diagnostic and treatment approaches.

Minor intron splicing is critical for survival of lethal prostate cancer

The evolutionarily conserved minor spliceosome (MiS) is required for protein expression of ∼714 minor intron-containing genes (MIGs) crucial for cell-cycle regulation, DNA repair, and MAP-kinase signaling. We explored the role of MIGs and MiS in cancer, taking prostate cancer (PCa) as an exemplar. Both androgen receptor signaling and elevated levels of U6atac, a MiS small nuclear RNA, regulate MiS activity, which is highest in advanced metastatic PCa. siU6atac-mediated MiS inhibition in PCa in vitro model systems resulted in aberrant minor intron splicing leading to cell-cycle G1 arrest. Small interfering RNA knocking down U6atac was ∼50% more efficient in lowering tumor burden in models of advanced therapy-resistant PCa compared with standard antiandrogen therapy. In lethal PCa, siU6atac disrupted the splicing of a crucial lineage dependency factor, the RE1-silencing factor (REST). Taken together, we have nominated MiS as a vulnerability for lethal PCa and potentially other cancers.

Deep learning model accurately classifies metastatic tumors from primary tumors based on mutational signatures

Metastatic propagation is the leading cause of death for most cancers. Prediction and elucidation of metastatic process is crucial for the treatment of cancer. Even though somatic mutations have been linked to tumorigenesis and metastasis, it is less explored whether metastatic events can be identified through genomic mutational signatures, which are concise descriptions of the mutational processes. Here, we developed MetaWise, a Deep Neural Network (DNN) model, by applying mutational signatures as input features calculated from Whole-Exome Sequencing (WES) data of TCGA and other metastatic cohorts. This model can accurately classify metastatic tumors from primary tumors and outperform traditional machine learning (ML) models and a deep learning (DL) model, DiaDeL. Signatures of non-coding mutations also have a major impact on the model's performance. SHapley Additive exPlanations (SHAP) and Local Surrogate (LIME) analyses identify several mutational signatures which are directly correlated to metastatic spread in cancers, including APOBEC-mutagenesis, UV-induced signatures, and DNA damage response deficiency signatures.

Micelle encapsulation zinc-doped copper oxide nanocomposites reverse Olaparib resistance in ovarian cancer by disrupting homologous recombination repair

Micelle Encapsulation Zinc-doped copper oxide nanocomposites (MEnZn-CuO NPs) is a novel doped metal nanomaterial prepared by our group based on Zinc doped copper oxide nanocomposites (Zn-CuO NPs) using non-micellar beam. Compared with Zn-CuO NPs, MEnZn-CuO NPs have uniform nanoproperties and high stability. In this study, we explored the anticancer effects of MEnZn-CuO NPs on human ovarian cancer cells. In addition to affecting cell proliferation, migration, apoptosis and autophagy, MEnZn-CuO NPs have a greater potential for clinical application by inducing HR repair defects in ovarian cancer cells in combination with poly (ADP-ribose) polymerase inhibitors for lethal effects.

DNA Methylation Landscapes of Prostate Cancer Brain Metastasis Are Shaped by Early Driver Genetic Alterations

Metastases from primary prostate cancers to rare locations, such as the brain, are becoming more common due to longer life expectancy resulting from improved treatments. Epigenetic dysregulation is a feature of primary prostate cancer, and distinct DNA methylation profiles have been shown to be associated with the mutually exclusive SPOP-mutant or TMPRSS2-ERG fusion genetic backgrounds. Using a cohort of prostate cancer brain metastases (PCBM) from 42 patients, with matched primary tumors for 17 patients, we carried out a DNA methylation analysis to examine the epigenetic distinction between primary prostate cancer and PCBM, the association between epigenetic alterations and mutational background, and particular epigenetic alterations that may be associated with PCBM. Multiregion sampling of PCBM revealed epigenetic stability within metastases. Aberrant methylation in PCBM was associated with mutational background and PRC2 complex activity, an effect that is particularly pronounced in SPOP-mutant PCBM. While PCBM displayed a CpG island hypermethylator phenotype, hypomethylation at the promoters of genes involved in neuroactive ligand-receptor interaction and cell adhesion molecules such as GABRB3, CLDN8, and CLDN4 was also observed, suggesting that cells from primary tumors may require specific reprogramming to form brain metastasis. This study revealed the DNA methylation landscapes of PCBM and the potential mechanisms and effects of PCBM-associated aberrant DNA methylation.

SIGNIFICANCE

DNA methylation analysis reveals the molecular characteristics of PCBM and may serve as a starting point for efforts to identify and target susceptibilities of these rare metastases.

Clinical and Genetic Analysis of Metastatic Prostate Cancer to the Central Nervous System: A Single-Institution Retrospective Experience

BACKGROUND

Prostate cancer (PC) rarely metastasizes to the central nervous system (CNS). In this retrospective single-institution study at a tertiary cancer center, we aimed to evaluate the clinical and genetic characteristics of advanced PC patients with CNS metastases.

PATIENTS AND METHODS

Between January 2010 and March 2020, 12 out of 579 patients with extracranial metastatic PC were identified to have CNS metastases based on imaging, including six patients with brain metastases (BMs), five patients with dural metastases, and one unknown. These patients were followed up through March 2022. Clinical data were compared to the overall cohort of patients evaluated at our cancer center during that decade. Genetics information was also analyzed for the patients with available data via cell-free DNA (cfDNA) blood samples.

RESULTS

Median time from development of extracranial metastatic disease to development of CNS metastases was 5.5 years (95% CI, 1.8-7.0). Median overall survival (mOS) from diagnosis of CNS metastases was 6.1 months (95% CI, 5.8-8.2). Notably, there was no significant difference in mOS after development of extracranial metastases in patients with CNS metastases (6.4 years; 95% CI, 4.6-7.9) compared to the patients without known CNS metastases (5.2 years; 95% CI, 4.6-5.7) (P = .91). For the cohort with CNS metastases, nine patients had germline testing and seven patients had somatic testing via cfDNA.

CONCLUSION

PC patients with CNS metastases did not often die from a neurological cause. With advancing therapies, the overall prognosis of metastatic PC continues to improve, and CNS metastases will become more common.

Molecular predictors of metastasis in patients with prostate cancer

INTRODUCTION

Prostate cancer is a serious threat to the health of older adults worldwide. The quality of life and survival time of patients sharply decline once metastasis occurs. Thus, early screening for prostate cancer is very advanced in developed countries. The detection methods used include Prostate-specific antigen (PSA) detection and digital rectal examination. However, the lack of universal access to early screening in some developing countries has resulted in an increased number of patients presenting with metastatic prostate cancer. In addition, the treatment methods for metastatic and localized prostate cancer are considerably different. In many patients, early-stage prostate cancer cells often metastasize due to delayed observation, negative PSA results, and delay in treatment time. Therefore, the identification of patients who are prone to metastasis is important for future clinical studies.

AREAS COVERED

this review introduced a large number of predictive molecules related to prostate cancer metastasis. These molecules involve the mutation and regulation of tumor cell genes, changes in the tumor microenvironment, and the liquid biopsy.

EXPERT OPINION

In next decade, PSMA PET/CT and liquid biopsy will be the excellent predicting tools, while ¹⁷⁷ Lu- PSMA-RLT will be showed excellent anti-tumor efficacy in mPCa patients.

Plexin-B1 Mutation Drives Metastasis in Prostate Cancer Mouse Models

Metastatic prostate cancer is essentially incurable and is a leading cause of cancer-related morbidity and mortality in men, yet the underlying molecular mechanisms are poorly understood. Plexins are transmembrane receptors for semaphorins with divergent roles in many forms of cancer. We show here that prostate epithelial cell-specific expression of a mutant form of Plexin-B1 (P1597L) which was identified in metastatic deposits in patients with prostate cancer, significantly increases metastasis, in particular metastasis to distant sites, in two transgenic mouse models of prostate cancer (PbCre⁺Pten^{fl /fl}Kras^G12V and PbCre⁺Pten^{fl /fl}p53^{fl/ fl} ). In contrast, prostate epithelial cell-specific expression of wild-type (WT) Plexin-B1 in PbCre⁺Pten^{fl /fl}Kras^G12V mice significantly decreases metastasis, showing that a single clinically relevant Pro1597Leu amino-acid change converts Plexin-B1 from a metastasis-suppressor to a metastasis-promoter. Furthermore, PLXNB1^P1597L significantly increased invasion of tumor cells into the prostate stroma, while PLXNB1^WT reduced invasion, suggesting that Plexin-B1 has a role in the initial stages of metastasis. Deletion of RhoA/C or PDZRhoGEF in Pten^{fl /fl}Kras^G12VPLXNB1^P1597L mice suppressed metastasis, implicating the Rho/ROCK pathway in this phenotypic switch. Germline deletion of Plexin-B1, to model anti-Plexin-B1 therapy, significantly decreased invasion and metastasis in both models. Our results demonstrate that Plexin-B1 plays a complex yet significant role in metastasis in mouse models of prostate cancer and is a potential therapeutic target to block the lethal spread of the disease.

Significance

Few therapeutic targets have been identified specifically for preventing locally invasive/oligometastatic prostate cancer from becoming more widely disseminated. Our findings suggest Plexin-B1 signaling, particularly from the clinically relevant P1597L mutant, is such a target.

Lineage plasticity in prostate cancer: Looking beyond intrinsic alterations

Emergence of small cell prostate cancer is linked to the plasticity of tumour cells and avoidance of environmental pressures. This process is thought to be reversable, however to-date evidence of this has been demonstrated in small-cell prostate cancer. To study the plasticity of prostate tumours, we look to clinical cohorts of patients covering the spectra of malignancy subtypes and utilise in vitro and in vivo models of disease progression. Current models have assisted in the understanding of the extremities of this plasticity, elucidating internal mechanisms and adaptations to stressors through transition to altered cell states. By interrogating the tumour microenvironment and earlier time points, we are beginning to form a deeper understanding of the full spectra of tumour plasticity. It could be proffered that this deeper understanding will lead to better patient outcome, with earlier interventions more likely to reverse plasticity and prevent trans-differentiation to the aggressive, small cell phenotype.