Defining the challenges and opportunities for using patient-derived models in prostate cancer research.

BACKGROUND: There are relatively few widely used models of prostate cancer compared to other common malignancies. This impedes translational prostate cancer research because the range of models does not reflect the diversity of disease seen in clinical practice. In response to this challenge, research laboratories around the world have been developing new patient-derived models of prostate cancer, including xenografts, organoids, and tumor explants. METHODS: In May 2023, we held a workshop at the Monash University Prato Campus for researchers with expertise in establishing and using a variety of patient-derived models of prostate cancer. This review summarizes our collective ideas on how patient-derived models are currently being used, the common challenges, and future opportunities for maximizing their usefulness in prostate cancer research. RESULTS: An increasing number of patient-derived models for prostate cancer are being developed. Despite their individual limitations and varying success rates, these models are valuable resources for exploring new concepts in prostate cancer biology and for preclinical testing of potential treatments. Here we focus on the need for larger collections of models that represent the changing treatment landscape of prostate cancer, robust readouts for preclinical testing, improved in vitro culture conditions, and integration of the tumor microenvironment. Additional priorities include ensuring model reproducibility, standardization, and replication, and streamlining the exchange of models and data sets among research groups. CONCLUSIONS: There are several opportunities to maximize the impact of patient-derived models on prostate cancer research. We must develop large, diverse and accessible cohorts of models and more sophisticated methods for emulating the intricacy of patient tumors. In this way, we can use the samples that are generously donated by patients to advance the outcomes of patients in the future.

A case of gangrenous cystitis with bilateral hydronephrosis 10 years after radiotherapy.

An 84-year-old woman who was admitted for protein-losing gastroenteropathy associated with radiation enteritis 10 years after pelvic radiotherapy developed pyelonephritis. She became anuric despite having an indwelling bladder catheter. Imaging studies revealed bladder wall thickening, bilateral hydroureter formation, and hydronephrosis. Autopsy findings led to a diagnosis of gangrenous cystitis (GC). Our case indicates that radiation-induced late effects may be an indirect cause of GC, not a direct cause as previously suggested, and that GC may induce bilateral vesicoureteral junction obstruction.

ATM suppresses c-Myc overexpression in the mammary epithelium in response to estrogen.

ATM gene mutation carriers are predisposed to estrogen-receptor-positive breast cancer (BC). ATM prevents BC oncogenesis by activating p53 in every cell; however, much remains unknown about tissue-specific oncogenesis after ATM loss. Here, we report that ATM controls the early transcriptional response to estrogens. This response depends on topoisomerase II (TOP2), which generates TOP2-DNA double-strand break (DSB) complexes and rejoins the breaks. When TOP2-mediated ligation fails, ATM facilitates DSB repair. After estrogen exposure, TOP2-dependent DSBs arise at the c-MYC enhancer in human BC cells, and their defective repair changes the activation profile of enhancers and induces the overexpression of many genes, including the c-MYC oncogene. CRISPR/Cas9 cleavage at the enhancer also causes c-MYC overexpression, indicating that this DSB causes c-MYC overexpression. Estrogen treatment induced c-Myc protein overexpression in mammary epithelial cells of ATM-deficient mice. In conclusion, ATM suppresses the c-Myc-driven proliferative effects of estrogens, possibly explaining such tissue-specific oncogenesis.

Cell Lines of Circulating Tumor Cells: What Is Known and What Needs to Be Resolved.

The importance of circulating tumor cells (CTC) is well recognized. However, the biological characteristics of CTC in the bloodstream have not yet been examined in detail, due to the limited number of CTC cell lines currently available. Thirty-nine CTC cell lines were reported by 2021. For successful cell culturing, these CTC cell lines were reviewed. Previous studies on short-term cultures of CTC also analyzed approaches for establishing the long-term culture of CTC. Negative selection, hypoxic conditions, three-dimensional conditions, and careful management are preferable for the long-term culture of CTC. However, the establishment of CTC cell lines is dependent on the specific characteristics of each cell type. Therefore, a method to establish CTC cell lines has not yet been developed. Further efforts are needed to resolve this issue.

A case of microsatellite instability-high clinically advanced castration-resistant prostate cancer showing a remarkable response to pembrolizumab sustained over at least 18 months.

Defective DNA mismatch repair genes can lead to microsatellite instability (MSI)-high status in prostate cancer (PC). Accumulation of replication errors in DNA leads to the production of abundant neoantigens, which could be targets for immune checkpoint inhibitors (CPIs). However, the incidence of MSI-high PC is low, and not all patients show a satisfactory therapeutic response to CPIs. Here, we present the case of a patient with MSI-high castration-resistant PC who showed a remarkable and durable response to pembrolizumab. The patient was resistant to abiraterone, docetaxel, and cabazitaxel and was suffering from multiple tumor-associated or treatment-related complications, such as urinary tract infection, infective endocarditis, and uncontrollable prostatic hemorrhage. Soon after the start of pembrolizumab therapy, the patient showed a dramatic decrease in prostate-specific antigen from 35.67 ng/mL to an undetectable level and a remarkable reduction in the size of a massive prostate mass and lymph node metastases, with an absence of treatment-related complications. Specimens from the transurethral resection of prostate cancer during cabazitaxel treatment for control of prostate bleeding and also that from the prostate biopsy at initial diagnosis revealed MSI-high status. Immunohistochemistry showed loss of MSH2 and MSH6, and whole-exome sequencing revealed an approximate tumor mutation burden of 61 mutations/Mb as well as biallelic loss of MSH2 Pembrolizumab could show a significant effect even in a heavily treated patient with MSI-high advanced PC. Accumulation of detailed clinical and genomic information of cases of MSI-high PC treated with pembrolizumab is necessary for optimal patient selection.

Clinical Impact of Detecting Low-Frequency Variants in Cell-Free DNA on Treatment of Castration-Resistant Prostate Cancer.

PURPOSE: Although cell-free DNA (cfDNA) testing is expected to drive cancer precision medicine, little is known about the significance of detecting low-frequency variants in circulating cell-free tumor DNA (ctDNA) in castration-resistant prostate cancer (CRPC). We aimed to identify genomic profile including low-frequency variants in ctDNA from patients with CRPC and investigate the clinical utility of detecting variants with variant allele frequency (VAF) below 1%. EXPERIMENTAL DESIGN: This prospective, multicenter cohort study enrolled patients with CRPC eligible for treatment with abiraterone or enzalutamide. We performed targeted sequencing of pretreatment cfDNA and paired leukocyte DNA with molecular barcodes, and ctDNA variants with a VAF ≥0.1% were detected using an in-house pipeline. We investigated progression-free survival (PFS) and overall survival (OS) after different ctDNA fraction cutoffs were applied. RESULTS: One hundred patients were analyzed (median follow-up 10.7 months). We detected deleterious ATM, BRCA2, and TP53 variants even in samples with ctDNA fraction below 2%. When the ctDNA fraction cutoff value of 0.4% was applied, significant differences in PFS and OS were found between patients with and without defects in ATM or BRCA2 [HR, 2.52; 95% confidence interval (CI), 1.24-5.11; P = 0.0091] and TP53 (HR, 3.74; 95% CI, 1.60-8.71; P = 0.0014). However, these differences were no longer observed when the ctDNA fraction cutoff value of 2% was applied, and approximately 50% of the samples were classified as ctDNA unquantifiable. CONCLUSIONS: Detecting low-frequency ctDNA variants with a VAF <1% is important to identify clinically informative genomic alterations in CRPC.

Establishment and characterization of a novel treatment-related neuroendocrine prostate cancer cell line KUCaP13.

The prevalence of neuroendocrine prostate cancer (NEPC) arising from adenocarcinoma (AC) upon potent androgen receptor (AR) pathway inhibition is increasing. Deeper understanding of NEPC biology and development of novel therapeutic agents are needed. However, research is hindered by the paucity of research models, especially cell lines developed from NEPC patients. We established a novel NEPC cell line, KUCaP13, from tissue of a patient initially diagnosed with AC which later recurred as NEPC. The cell line has been maintained permanently in vitro under regular cell culture conditions and is amenable to gene engineering with lentivirus. KUCaP13 cells lack the expression of AR and overexpress NEPC-associated genes, including SOX2, EZH2, AURKA, PEG10, POU3F2, ENO2, and FOXA2. Importantly, the cell line maintains the homozygous deletion of CHD1, which was confirmed in the primary AC of the index patient. Loss of heterozygosity of TP53 and PTEN, and an allelic loss of RB1 with a transcriptomic signature compatible with Rb pathway aberration were revealed. Knockdown of PEG10 using shRNA significantly suppressed growth in vivo. Introduction of luciferase allowed serial monitoring of cells implanted orthotopically or in the renal subcapsule. Although H3K27me was reduced by EZH2 inhibition, reversion to AC was not observed. KUCaP13 is the first patient-derived, treatment-related NEPC cell line with triple loss of tumor suppressors critical for NEPC development through lineage plasticity. It could be valuable in research to deepen the understanding of NEPC.

99mTc-mercaptoacetyltriglycine Cortical Renography Predicts Outcomes in Adult Living Donor Renal Transplant Recipients.

BACKGROUND: The clinical utility of 99mTc-mercaptoacetyltriglycine cortical renography for the prediction of graft function in kidney transplant recipients has been unknown. METHODS: We retrospectively reviewed post-transplant cortical renograms in 40 kidney transplant recipients. We analyzed the correlation between T1/2 (elimination half-life) and graft function (measured-to-expected glomerular filtration rate [GFR]) 1 week, and 1, 3, and 6 months post operation compared with whole-kidney renograms. RESULTS: Delayed drainage (T1/2 > 11 minutes) was observed in 22 recipients (55%). T1/2 and postoperative GFR ratio were inversely correlated (1 week: R2 = 0.317, P = .0002; 1 month: R2 = 0.206, P = .003; 3 months: R2 = 0.117, P = .031; 6 months: R2 = 0.161, P = .010). Recipients with delayed drainage had a significantly lower GFR ratio than those with normal drainage 1 week (median, 0.93 vs 1.32; P = .001), 1 month (median, 1.65 vs 2.23; P = .0010), 3 months (median, 1.55 vs 2.17; P = .041), and 6 months (median, 1.67 vs 2.34; P = .018) post operation, respectively. Whole-kidney renograms failed to discriminate recipients with lower GFR ratio at 1, 3, and 6 months. CONCLUSIONS: T1/2 in post-transplant cortical renography was inversely correlated with early graft function and may predict early post-transplant graft function.

[A Case of Metastatic Clear Cell Renal Cell Carcinoma Showing Long-Term Complete Response after the Discontinuation of Tyrosine Kinase Inhibitor].

Randomized phase III trials demonstrated superiority of targeted therapy with tyrosine kinase inhibitors over cytokine-based therapy as first-line therapy for metastatic renal cell carcinoma. However, the rate of complete response (CR) with targeted therapy is smaller than that with cytokine-based therapy. A 47-year-old man was referred to our hospital with a 12 cm left renal tumor and polycythemia. He was diagnosed with renal cancer, cT3aN0M1, with multiple lung metastases. He underwent cytoreductive nephrectomy, with the histopathological diagnosis of clear cell renal cell carcinoma, Fuhrman nuclear grade 2, INFb, pT2b. Three months postoperatively, spontaneous regression of lung metastases was observed. Seventeen months postoperatively, a 17×13 mm retroperitoneal tumor facing the pancreas recurred. CR of the recurrent tumor was achieved by targeted therapy with sunitinib for 12 months. This CR was maintained for 32 months after the discontinuation of targeted therapy with sunitinib.

[Prostate Cancer Diagnosed during Androgen Replacement Therapy for Late-Onset Hypogonadism Treatment: A Case Report].

We report a 60-year-old man with prostate cancer diagnosed during androgen replacement therapy (ART) for late onset hypogonadism after surgery for pituitary adenoma. He was refered to the department of urology since prostate specific antigen values were elevated after 6 months of ART. After the diagnosis of prostate cancer, ART was discontinued, and robot-asssited laparoscopic radical prostatectomy with pelvic lymphadenoctomy was performed. Pathological examination revealed Gleason score 4 + 5 prostate adenocarcinoma with seminal vesicle invasion and lymph node metastasis(pT3bN1). He has stayed biochemically and radiologically disease-free 33 months postoperatively.

[Reactive Arthritis during the Second Course of Intravesical BCG Therapy Requiring Administration of Methotrexate : A Case Report].

Reactive arthritis, formerly called Reiter's syndrome, is one of the rare complications following intravesical instillation of Bacillus Calmette Guerin (BCG). A 58-year-old man was admitted to our hospital because of fever, hyperemia of conjunctiva, and arthralgia following the second course of intravesical instillation of BCG in the treatment of pT1 and pTis bladder cancer. We diagnosed him with reactive arthritis due to the clinical course. Reactive arthritis is usually well controlled with the discontinuation of instillation and administration of nonsteroidal anti-inflammatory drugs (NSAIDs). However, his symptoms were not improved after administration of NSAIDs, prednisolone, and isoniazid. Following initiation of methotrexate, however, there was remission. He has been free from recurrence of bladder cancer for 20 months.

[Port-Site Metastasis of Prostate Cancer after Robot-Assisted Laparoscopic Prostatectomy : A Case Report].

The incidence of port-site metastasis in urologic laparoscopic surgery is low, especially in prostate cancer, with 4 reported cases to date. A 65-year-old man was introduced to our hospital presenting with gross hematuria and dysuria. His prostate-specific antigen (PSA) level was 3.1 ng/ml. He was diagnosed with poorly differentiated adenocarcinoma of the prostate, Gleason 9 (5＋4), cT3aN0M0 with non-invasive urothelial cancer of bladder (pTaN0M0, low grade). Robot-assisted laparoscopic prostatectomy was performed. Histopathological examination revealed adenocarcinoma, Gleason 9 (5＋4), pT3bN0, and surgical margins were positive. Eighteen weeks postoperatively, local recurrence, lymph node metastases, and a port-site metastasis were observed. Androgen deprivation therapy with 4 courses of induction docetaxel chemotherapy achieved a complete response on imaging study, 2 years postoperatively.

[Urinary Diversion Using an Appendicovesicostomy for Idiopathic Urethral Stricture : A Case Report].

A 55-year-old woman was referred to our hospital with dysuria. We were unable to catheterize her using a nelaton catheter because of a urethral stricture, resulting in a large residual urine volume on ultrasonography. The circumference of the periurethral tissue was also thickened and the entire length of the urethra was stenotic, without apparent cause, on magnetic resonance imaging. Biopsy did not reveal malignancy. The pathological diagnosis of the periurethral tissue was simply fibrosis, and there was no definitive diagnosis. We decided to place a guidewire to attempt transurethral dilation, but it was unsuccessful because of the urethral stricture. The patient then underwent Mitrofanoff appendicovesicostomy. Three years later, there was no difficulty with catheterization through the appendix, despite her suffering from a bladder stone during the interim. We consider the Mitrofanoff appendicovesicostomy a good substitute technique for catheterization in patients with very severe urethral stricture.

[Advanced Adenocarcinoma of the Bladder after Augmentation Gastrocystoplasty].

A 29-year-old woman had undergone gastrocystoplasty with Mitrofanoff appendicovesicostomy for urethral trauma at 9 years of age. Since then, she was being followed up for performing clean intermittent self-catheterization at regular intervals. Twenty years after the surgery, she presented with gross hematuria. Ultrasonographic findings revealed bilateral hydronephrosis. Cystoscopy and computed tomography (CT) revealed invasive bladder cancer with pelvic lymph node metastases. A biopsy confirmed the diagnosis of adenocarcinoma with signet ring cell carcinoma. Subsequently, neo-adjuvant combination chemotherapy with TS-1 and cisplatin (CDDP) was initiated, which was followed by open radical cystectomy with extended pelvic lymphadenectomy. The tumor was found to infiltrate from the anastomotic site into the entire native bladder and histopathological diagnosis was muscle invasive adenocarcinoma with neuroendocrine differentiation and lymph node metastasis (ypT3bN2). TS-1 was continued as adjuvant chemotherapy and the patient did not have any evidence of recurrence for 12 months postoperatively.

[A Case of Rapidly Progressive Metastatic Castration-Resistant Prostate Cancer : Durable Control by Early Induction of Carboplatin and Paclitaxel].

A 60-year-old man visited the previous hospital with difficulty of urination in July 2004. Serum prostate specific antigen (PSA) was 5.4 ng/ml and he was diagnosed with prostate adenocarcinoma, Gleason Score 4＋4＝8, cT1cN0M0. Although radical prostatectomy was recommended, he refused any treatment and never visited that hospital again. He was admitted to our hospital for exacerbation of dysuria with anal pain newly appeared in March 2005, when it was found that his disease had progressed to cT4N0M1b (thoracic spine, sacroiliac joint and ischium). Serum PSA decreased and the primary lesion shrunk after androgen deprivation therapy (ADT), whereas the left ischial lesion enlarged and serum carcinoembryonic antigen (CEA) and alkaline phosphatase (ALP) were elevated. For the castration-resistant progression, 30 Gy of local irradiation to the left ischial lesion and systemic chemotherapy with carboplatin (CBDCA) and paclitaxel (PTX) were administered, which led the patient to complete radiological and biochemical remission. The chemotherapy was discontinued in 2009 after the 18th course, and then ADT was also discontinued in 2010. The patient remains free from radiological or biochemical evidence of disease at the latest follow up in December 2014.

Large Retroperitoneal Mass Diagnosed as Adrenal Chronic Expanding Hematoma.

Chronic expanding hematoma is defined as a structure with central mass of blood and granulation tissue encapsulated with dense fibrous membrane that slowly grows over a month. We report a case of a 67-year-old man with left adrenal chronic expanding hematoma who underwent surgical resection after 7-year surveillance, presenting natural history of an adrenal chronic expanding hematoma.

[Pelvic lymph node dissection in robot-assisted laparoscopic radical prostatectomy: safety and adequacy in introductory series].

To evaluate the safety and adequacy of pelvic lymph node dissection (LND) in robot-assisted laparoscopic radical prostatectomy (RALP) in an institutional introductory case series, we retrospectively reviewed the first 135 patients with clinically localized prostate cancer who underwent RALP with no LND (n＝78), limited LND (LLND, n＝40), or extended LND (ELND, n＝17). Data were collected foroperating time itemized by each surgical procedure, estimated blood loss, lymph node yield, total postoperative drainage amount, postoperative days to drainage tube removal and urethral catheter removal, perioperative complication, and postoperative hospital stay. LLND and ELND took a median of 19 (interquartile range 15-22) and 69 (60.5-91) min, respectively. Total operating time was significantly longer (p＜0.0001) for those with ELND (median 329 min ; interquartile 272-375) than those with no LND (239 ; 195-292) and LLND (281 ; 230-314). Lymph node yield was 7 (5-9) and 23 (12-30) for LLND and ELND, respectively, which was equivalent to the yield of lymph nodes dissected in open prostatectomy ashistorical and institutional control. Although total drainage amount was significantly greater and drainage tube was placed significantly longer in the ELND group, there were no significant differences in time to urethral catheter removal and postoperative hospital stay among the groups. There were no severe perioperative complications associated with LND except for prolonged lymph fistula in each case of the LLND and ELND groups. In conclusion, LND can be performed safely and adequately in introductory RALP cases.

[A case of adrenal metastasectomy in renal cell carcinoma after neoadjuvant therapy with sunitinib].

A 58-year-old man had undergone laparoscopic radical nephrectomy for right renal cell carcinoma. The histopathological diagnosis was clear cell carcinoma, grade 2＞3, pT1b. Two years and 10 months postoperatively, computed tomography scans demonstrated an enhanced mass on the right adrenal gland. As we could not detect other metastatic lesions, it was diagnosed as solitary adrenal metastasis of renal cell carcinoma. Albeit metastasectomy was planned with curative intent, right hemihepatectomy was also required for surgical removal because the tumor was adherent to the right lobe of the liver broadly and had indistinct margins. So we started neoadjuvant therapy with sunitinib. Eight courses of treatment shrunk the metastatic tumor enough to allow it to be removed completely without partial hepatectomy. Neoadjuvant therapy with the molecular targeted drugs may provide an effective option for metastasectomy in renal cell carcinoma regarding increased curability and decreased the risk of an operation.

[Case of juxtaglomerular cell tumor (reninoma) treated with laparoscopic partial nephrectomy].

We report a case of a 22-year-old male with juxtaglomerular cell tumor treated with laparoscopic partial nephrectomy. He was referred to our hospital with hypertension, high concentration of plasma renin activity (PRA) and renal mass. Dynamic enhanced computed tomography showed 17-mm weak contrast-enhancing tumor at the upper pole of the left kidney. Renin suppression and stimulation test revealed autonomous renin secretion although renal venous sampling failed to show significant difference in the PRA between the right and left renal vein. We performed laparoscopic left partial nephrectomy. The histological diagnosis was juxtaglomerular cell tumor. After the operation, his blood pressure and PRA were immediately normalized. Juxtaglomerular cell tumor is an important renal tumor as a curable cause of secondary hypertension.