Treatment escalation and de-escalation of de-novo metastatic castration-sensitive prostate cancer.

Androgen receptor signaling inhibitors combined with androgen deprivation therapy have become the standard of care for metastatic castration-sensitive prostate cancer (mCSPC), regardless of tumor volume or risk. However, survival of approximately one-third of these patients has not improved, necessitating further treatment escalation. On the other hand, for patients with oligometastatic mCSPC, there is an emerging role for local radiation therapy. Although data remain scarce, it is expected that treatment of both primary tumor as well as metastasis-directed therapy may improve survival outcomes. In these patients, systemic therapy may be de-escalated to intermittent therapy. However, precise risk stratification is necessary for risk-based treatment escalation or de-escalation. In addition to risk stratification based on clinical parameters, research has been conducted to incorporate genomic and/or transcriptomic data into risk stratification. In future, an integrated risk model is expected to precisely stratify patients and guide treatment strategies. Here, we first review the transition of the standard treatment for mCSPC over the last decade and further discuss the newest concept of escalating or de-escalating treatment using a multi-modal approach based on the currently available literature.

[The Association of Docetaxel Side Effects and Introduction of Subsequent Cabazitaxel for Castration-Resistant Prostate Cancer : A Clinical Study].

The administration of cabazitaxel for patients with castration-resistant prostate cancer (CRPC) requires prior docetaxel therapy. Sequential chemotherapy may have to be discontinued due to docetaxelassociated side effects. This study investigated the relationship between treatment outcome of docetaxel and cabazitaxel and their associated side effects. We retrospectively analyzed 69 patients with CRPC who had been administered docetaxel withand without subsequent cabazitaxel at Toyonaka Municipal Hospital from October 2014 to June 2022. Twenty-eight patients (41%) discontinued docetaxel because of side effects, and the median number of docetaxel cycles at discontinuation was 2 (range : 1-11). Fourteen of these patients received no treatment following docetaxel. A comparison of the 28 patients who had discontinued docetaxel due to side effects with 41 patients who had not revealed a significant difference in the total numbers of chemotherapy cycles (2.5 vs 9 ; P＜0.001) and time to treatment failure (56 days vs 301 days ; P＝ 0.001), with a trend toward shorter overall survival from the start of docetaxel treatment (259 days vs 512 days ; P＝0.06). Multivariate analysis identified discontinuation of docetaxel due to side effects (OR＝0.07 ; P＜0.001) and lower hemoglobin (OR＝0.01 ; P＝0.001) as significant factors inhibiting the introduction of cabazitaxel. Reducing the side effects of docetaxel, including early drug switching, may allow more CRPC patients to be reached with cabazitaxel. Consequently, the resulting taxane-based chemotherapy may contribute to an additional survival advantage.

[A Case of Metastatic Prostate Cancer with Neuroendocrine Differentiation with Long-Term Survival after Multidisciplinary Therapy].

A 74-year-old man visited the urology clinic with the chief complaint of urinary retention in December 2014. Serum level of initial prostate specific antigen (PSA) was 50 ng/ml and he was diagnosed with Gleason Score 4＋4 prostate adenocarcinoma with regional lymphadenopathy (cT3aN1M0). PSA level had declined after the treatment with combined androgen blockade. In November 2018, he was diagnosed with castration resistant prostate cancer (CRPC) as local progression was detected by computed tomography (CT) while PSA level did not increase. Since local symptoms worsened, resulting in repeated hematuria after the treatment with enzalutamide, palliative radiation therapy to the prostate (45 Gy) was performed. Five months later, follow-up CT showed multiple metastasis in bilateral lung and left testicle. Serum level of neuron-specific enolase (NSE) was 24.4 ng/ml without an elevated in serum PSA level. He received rebiopsy of the prostate, but no malignant findings were observed. Consequently, bilateral orchiectomy was performed for diagnosis of left testicular tumor. Pathological examination revealed metastasis of neuroendocrine prostate cancer (NEPC). Chemotherapy using cisplatin and irinotecan was administered after orchiectomy. Complete response of lung lesions was achieved and serum level of NSE decreased within normal range. No recurrence has been confirmed for 4 years after the completion of chemotherapy.

Facile synthesis of elastin nanogels encapsulated decursin for castrated resistance prostate cancer therapy.

Nanogels offer hope for precise drug delivery, while addressing drug delivery hurdles is vital for effective prostate cancer (PCa) management. We developed an injectable elastin nanogels (ENG) for efficient drug delivery system to overcome castration-resistant prostate cancer (CRPC) by delivering Decursin, a small molecule inhibitor that blocks Wnt/ßcatenin pathways for PCa. The ENG exhibited favourable characteristics such as biocompatibility, flexibility, and low toxicity. In this study, size, shape, surface charge, chemical composition, thermal stability, and other properties of ENG were used to confirm the successful synthesis and incorporation of Decursin (DEC) into elastin nanogels (ENG) for prostate cancer therapy. In vitro studies demonstrated sustained release of DEC from the ENG over 120 h, with a pH-dependent release pattern. DU145 cell line induces moderate cytotoxicity of DEC-ENG indicates that nanomedicine has an impact on cell viability and helps strike a balance between therapeutics efficacy and safety while the EPR effect enables targeted drug delivery to prostate tumor sites compared to free DEC. Morphological analysis further supported the effectiveness of DEC-ENG in inducing cell death. Overall, these findings highlight the promising role of ENG-encapsulated decursin as a targeted drug delivery system for CRPC.

Synthesis of curcumin derivatives targeting androgen receptor for castration-resistant prostate cancer therapy.

In this work, a series of curcumin derivatives (1a-1h, 2a-2g, and 3a-3c) were synthesized for the suppression of castration-resistant prostate cancer cells. All synthesized compounds were characterized by 1H NMR, 13C NMR, HRMS, and melting point. The in vitro cytotoxicity study shows that compounds 1a, 1e, 1f, 1h, 2g, 3a, and 3c display similar or enhanced cytotoxicity against 22Rv1 and C4-2 cells as compared to ASC-J9, other synthesized compounds display reduced cytotoxicity against 22Rv1 and C4-2 cells as compared to ASC-J9. Molecular docking simulation was performed to study the binding affinity and probable binding modes of the synthesized compounds with androgen receptor. The results show that all synthesized compounds exhibit higher cdocker interaction energies as compared to ASC-J9. Compounds 1h, 2g, and 3c not only show strong cytotoxicity against 22Rv1 and C4-2 cells but also exhibit high binding affinity with androgen receptor. In androgen receptor suppression study, compounds 1f and 2g show similar androgen receptor suppression effect as compared to ASC-J9 on C4-2 cells, compound 3c displays significantly enhanced AR suppression effect as compared to ASC-J9, 1f and 2g. Compounds 1a, 1e, 1f, 1h, 2g, 3a and 3c prepared in this work have significant potential for castration-resistant prostate cancer therapy.

Discovery of a peptide proteolysis-targeting chimera (PROTAC) drug of p300 for prostate cancer therapy.

BACKGROUND: The E1A-associated protein p300 (p300) has emerged as a promising target for cancer therapy due to its crucial role in promoting oncogenic signaling pathways in various cancers, including prostate cancer. This need is particularly significant in prostate cancer. While androgen deprivation therapy (ADT) has demonstrated promising efficacy in prostate cancer, its long-term use can eventually lead to the development of castration-resistant prostate cancer (CRPC) and neuroendocrine prostate cancer (NEPC). Notably, p300 has been identified as an important co-activator of the androgen receptor (AR), highlighting its significance in prostate cancer progression. Moreover, recent studies have revealed the involvement of p300 in AR-independent oncogenes associated with NEPC. Therefore, the blockade of p300 may emerge as an effective therapeutic strategy to address the challenges posed by both CRPC and NEPC. METHODS: We employed AI-assisted design to develop a peptide-based PROTAC (proteolysis-targeting chimera) drug that targets p300, effectively degrading p300 in vitro and in vivo utilizing nano-selenium as a peptide drug delivery system. FINDINGS: Our p300-targeting peptide PROTAC drug demonstrated effective p300 degradation and cancer cell-killing capabilities in both CRPC, AR-negative, and NEPC cells. This study demonstrated the efficacy of a p300-targeting drug in NEPC cells. In both AR-positive and AR-negative mouse models, the p300 PROTAC drug showed potent p300 degradation and tumor suppression. INTERPRETATION: The design of peptide PROTAC drug targeting p300 is feasible and represents an efficient therapeutic strategy for CRPC, AR-negative prostate cancer, and NEPC. FUNDING: The funding details can be found in the Acknowledgements section.

Real-world economic burden associated with disease progression from metastatic castration-sensitive to castration-resistant prostate cancer on treatment in the United States.

BACKGROUND: The advent of next-generation imaging will likely reduce nonmetastatic prostate cancer (PC) prevalence and increase identification of metastatic prostate cancer cases, resulting in two predominant advanced stages in the metastatic setting. There is a need to characterize changes in health care resource utilization (HRU) and costs when metastatic castration-sensitive PC (mCSPC) progresses to metastatic castration-resistant PC (mCRPC) to identify value drivers from current and new treatments. OBJECTIVE: To describe treatment patterns, HRU, and total health care costs among patients with mCSPC, before and after progression to mCRPC. METHODS: Clinical data from the Flatiron Metastatic PC Core Registry (January 1, 2013, to December 1, 2021) and linked claims from Komodo Health (January 1, 2014, to December 1, 2021) were used to identify patients with progression from mCSPC to mCRPC (date of progression was the index date) and subsequently initiated first-line mCRPC therapy on/after January 1, 2017. Treatment patterns and all-cause/PC-related HRU and health care costs were described per-patient-per-month (PPPM), separately for no more than 12 months pre-index (mCSPC disease state) and post-index (mCRPC disease state). Costs (payer's perspective) included those for services/procedures from medical claims and costs from pharmacy claims. Continuous HRU and costs were compared between the mCSPC and mCRPC disease states using Wilcoxon signed rank tests. RESULTS: Among 296 patients with mCSPC progressing to mCRPC (median age 69.0 years, 60.5% White, 15.9% Black), use of systemic therapies with androgen deprivation therapy increased dramatically from 35.1% in the mCSPC disease state to 92.9% in the mCRPC disease state, and use of androgen deprivation therapy monotherapy decreased from 25.7% to 2.4%, respectively. Although 39.2% received none of these therapies in the mCSPC disease state, this proportion decreased to 4.7% after transition to mCRPC. The mean number of days with PC-related outpatient visits increased from 1.57 to 2.16 PPPM in the mCSPC and mCRPC disease states (P < 0.001). From the mCSPC to mCRPC disease states, mean all-cause total health care costs PPPM increased from $4,424 (medical costs: $2,846) to $9,717 (medical costs: $4,654), and mean PC-related total health care costs PPPM increased from $2,859 (medical costs: $1,626) to $8,012 (medical costs: $3,285; all P < 0.001). CONCLUSIONS: In this real-world study of patients with disease progression from mCSPC to mCRPC in US clinical practice, nearly 2-in-3 patients did not receive treatment with additional systemic therapies before progression to castration resistance. Post-progression, mean PC-related total costs increased nearly 3-fold, with a more than 2-fold increase in PC-related medical costs. Use of additional systemic therapies may delay the time and cost associated with disease progression to castration resistance.

Single-cell analysis of treatment-resistant prostate cancer: Implications of cell state changes for cell surface antigen-targeted therapies.

Targeting cell surface molecules using radioligand and antibody-based therapies has yielded considerable success across cancers. However, it remains unclear how the expression of putative lineage markers, particularly cell surface molecules, varies in the process of lineage plasticity, wherein tumor cells alter their identity and acquire new oncogenic properties. A notable example of lineage plasticity is the transformation of prostate adenocarcinoma (PRAD) to neuroendocrine prostate cancer (NEPC)-a growing resistance mechanism that results in the loss of responsiveness to androgen blockade and portends dismal patient survival. To understand how lineage markers vary across the evolution of lineage plasticity in prostate cancer, we applied single-cell analyses to 21 human prostate tumor biopsies and two genetically engineered mouse models, together with tissue microarray analysis on 131 tumor samples. Not only did we observe a higher degree of phenotypic heterogeneity in castrate-resistant PRAD and NEPC than previously anticipated but also found that the expression of molecules targeted therapeutically, namely PSMA, STEAP1, STEAP2, TROP2, CEACAM5, and DLL3, varied within a subset of gene-regulatory networks (GRNs). We also noted that NEPC and small cell lung cancer subtypes shared a set of GRNs, indicative of conserved biologic pathways that may be exploited therapeutically across tumor types. While this extreme level of transcriptional heterogeneity, particularly in cell surface marker expression, may mitigate the durability of clinical responses to current and future antigen-directed therapies, its delineation may yield signatures for patient selection in clinical trials, potentially across distinct cancer types.

PSA doubling time 4.65 months as an optimal cut-off of Japanese nonmetastatic castration-resistant prostate cancer.

A multicenter study of nonmetastatic castration-resistant prostate cancer (nmCRPC) was conducted to identify the optimal cut-off value of prostate-specific antigen (PSA) doubling time (PSADT) that correlated with the prognosis in Japanese nmCRPC. Of the 515 patients diagnosed and treated for nmCRPC at 25 participating Japanese Urological Oncology Group centers, 450 patients with complete clinical information were included. The prognostic values of clinical factors were evaluated with respect to prostate specific antigen progression-free (PFS), cancer-specific survival (CSS), and overall survival (OS). The optimal cutoff value of PSADT was identified using survival tree analysis by Python. The Median PSA and PSADT at diagnosis of nmCRPC were 3.3 ng/ml, and 5.2 months, respectively. Patients treated with novel hormonal therapy (NHT) showed significantly longer PFS (HR: hazard ratio 0.38, p < 0.0001) and PFS2 (HR 0.45, p < 0.0001) than those treated with vintage nonsteroidal antiandrogen agent (Vintage). The survival tree identified 4.65 months as the most prognostic PSADT cutoff point. Among the clinical and pathological factors PSADT of < 4.65 months remained an independent prognostic factor for OS (HR 2.96, p = 0.0003) and CSS (HR 3.66, p < 0.0001). Current data represented optimal cut-off of PSADT 4.65 months for a Japanese nmCRPC.

Natural History of Nonmetastatic Prostate Cancer Managed With Watchful Waiting.

Importance: It is uncertain to what extent watchful waiting (WW) in men with nonmetastatic prostate cancer (PCa) and a life expectancy of less than 10 years is associated with adverse consequences. Objective: To report transitions to androgen deprivation therapy (ADT), castration-resistant prostate cancer (CRPC), death from PCa, or death from other causes in men treated with a WW strategy. Design, Setting, and Participants: This nationwide, population-based cohort study included men with nonmetastatic PCa diagnosed since 2007 and registered in the National Prostate Cancer Register of Sweden with WW as the primary treatment strategy and with life expectancy less than 10 years. Life expectancy was calculated based on age, the Charlson Comorbidity Index (CCI), and a drug comorbidity index. Observed state transition models complemented observed data to extend follow-up to more than 20 years. Analyses were performed between 2022 and 2023. Exposure: Nonmetastatic PCa. Main Outcomes and Measures: Transitions to ADT, CRPC, death from PCa, and death from other causes were measured using state transition modeling. Results: The sample included 5234 men (median [IQR] age at diagnosis, 81 [79-84] years). After 5 years, 954 men with low-risk PCa (66.2%) and 740 with high-risk PCa (36.1%) were still alive and not receiving ADT. At 10 years, the corresponding proportions were 25.5% (n = 367) and 10.4% (n = 213), respectively. After 10 years, 59 men with low-risk PCa (4.1%) and 221 with high-risk PCa (10.8%) had transitioned to CRPC. Ten years after diagnosis, 1330 deaths in the low-risk group (92.3%) and 1724 in the high-risk group (84.1%) were from causes other than PCa. Conclusions and Relevance: These findings suggest that the WW management strategy is appropriate for minimizing adverse consequences of PCa in men with a baseline life expectancy of less than 10 years.

Impact of Novel Agents on Patient Characteristics, Treatment Patterns, and Outcomes in Patients With Metastatic Castration-resistant Prostate Cancer.

BACKGROUND/AIM: The therapeutic landscape for metastatic castration-resistant prostate cancer (mCRPC) has changed dramatically with the introduction of several novel agents. However, limited data are available to determine whether the introduction of novel agents affected patient characteristics, treatment patterns, and outcomes compared with the period when these agents were not available. The objective of this study was to evaluate the impact of the introduction of novel mCRPC agents on patient characteristics, treatment patterns, and outcomes. PATIENTS AND METHODS: Two cohorts of Japanese patients diagnosed with mCRPC between 2009 and 2014 (Epoch 1) and 2015 and 2019 (Epoch 2) were retrospectively analyzed. RESULTS: A total of 125 treatment-naïve mCRPC patients, consisting of 42 patients in Epoch 1 and 83 patients in Epoch 2, were evaluated. We obtained the following results: (i) a dramatic shift in the first-line treatment from docetaxel to androgen receptor axis-targeted agents (ARATs), (ii) an age range expansion for first-line treatment, and (iii) an overall survival (OS) advantage in Eopch 2 compared to Epoch 1. Multivariate analysis in the overall population showed that Epoch 2 and low prostate-specific antigen (PSA) levels at the start of first-line treatment were independent prognostic factors for OS. CONCLUSION: In real-world mCRPC practice, the introduction of novel agents has improved the prognosis of mCRPC while allowing more patients to receive mCRPC treatment across a broad age range. In addition, low PSA levels at the start of first-line treatment were associated with improved OS, indicating the importance of starting mCRPC treatment while PSA levels are low.

Efficacy of Enzalutamide Rechallenge for Metastatic Castration-Resistant Prostate Cancer.

OBJECTIVE: There have been several reports on rechallenge with docetaxel, cabazitaxel, abiraterone acetate, or ethinylestradiol for metastatic castration-resistant prostate cancer (mCRPC). However, the efficacy of enzalutamide rechallenge for mCRPC has not been evaluated. METHODS: We retrospectively reviewed 63 consecutive patients who received enzalutamide for mCRPC at our institution between 2014 and 2022. Eight of these patients underwent rechallenge with enzalutamide after disease progression on prior enzalutamide and other therapy and were the focus of this study. The prostate-specific antigen (PSA) response (PSA decrease >50%), PSA progression-free survival, treatment duration, overall survival (OS) after CRPC, and treatment-related adverse events were evaluated. RESULTS: PSA decline to enzalutamide rechallenge was observed in 6 patients (75%), of which 2 patients had a PSA response. The median treatment duration was 4 months (range 1-12) and median PSA progression-free survival was 3 months (range 1-7). Median OS after CRPC was 41 months. OS after CRPC was not increased in patients with a PSA response. No toxicities were worse than grade ≥3. CONCLUSION: Enzalutamide rechallenge achieved a PSA response in a quarter of our patients with mCRPC after disease progression on prior enzalutamide. However, no improvement of OS was identified in these patients.

Long-Term Pharmacokinetic Follow-Up of Abiraterone Acetate in Patients with Metastatic Castration-Resistant Prostate Cancer.

This ABIGENE pharmacokinetic (PK) study sought mainly to characterize the unchanged drug PK during long-term abiraterone acetate (AA) administration in advanced prostate cancer patients (81 patients). It was observed that individual AA concentrations remained constant over treatment time, with no noticeable changes during repeated long-term drug administration for up to 120 days. There was no correlation between AA concentrations and survival outcomes. However, a significant association between higher AA concentrations and better clinical benefit was observed (p = 0.041). The safety data did not correlate with the AA PK data. A significant positive correlation (r = 0.40, p < 0.001) was observed between mean AA concentration and patient age: the older the patient, the higher the AA concentration. Patient age was found to impact steady-state AA concentration: the older the patient, the higher the mean AA concentration. Altogether, these data may help to guide future research and clinical trials in order to maximize the benefits of AA metastatic castration-resistant prostate cancer patients.

A phase II study (AARDVARC) of AZD4635 in combination with durvalumab and cabazitaxel in patients with progressive, metastatic, castration-resistant prostate cancer.

BACKGROUND: This phase II nonrandomized study evaluated the efficacy and safety of AZD4635 in combination with durvalumab (Arm A) or durvalumab plus cabazitaxel (Arm B) in patients with metastatic castration-resistant prostate cancer (mCRPC) previously treated with docetaxel and ≥1 novel hormonal agent. PATIENTS AND METHODS: The primary endpoint was radiographic progression-free survival (rPFS) per RECIST v1.1 (soft tissue) or the Prostate Cancer Clinical Trials Working Group 3 (bone). Secondary endpoints included safety, tolerability, overall survival, confirmed prostate-specific antigen (PSA50) response, pharmacokinetics, and objective response rate. Enrollment in Arm A was stopped following a sponsor decision unrelated to safety. The study was stopped based on the planned futility analysis due to low PSA50 response in Arm B. RESULTS: In the final analysis (1 November 2021), 30 patients were treated (Arm A, n = 2; Arm B, n = 28). The median rPFS in Arm B was 5.8 months (95% confidence interval 4.2-not calculable). Median rPFS was 5.8 months versus 4.2 months for patients with high versus low blood-based adenosine signature. The most common treatment-related adverse events in Arm B were nausea (50.0%), diarrhea (46.4%), anemia and neutropenia (both 35.7%), asthenia (32.1%), and vomiting (28.6%). Overall, AZD4635 in combination with durvalumab or AZD4635 in combination with cabazitaxel and durvalumab showed limited efficacy in patients with mCRPC. CONCLUSIONS: Although the safety profile of both combinations was consistent with known safety data of the individual agents, the results of this trial do not support further development of the combinations.

Androgen Receptor Splice Variant 7 in Asian Patients With Metastatic Castration-Resistant Prostate Cancer.

PURPOSE: Androgen receptor splice variant 7 (ARV-7) is a resistance mechanism to hormonal therapy in metastatic castrate-resistant prostate cancer (mCRPC). It has been associated with poor outcomes. On progression to castrate resistance, ARV-7 positivity has been identified in global populations at an incidence of 17.8%-28.8%. Here, we characterize the incidence of ARV-7 positivity in Asian patients with mCRPC in a prospective fashion and evaluate its implications on treatment outcomes. METHODS: Patients with mCRPC from multiple centers in Southeast and East Asia were enrolled in a prospective manner before initiation of androgen receptor signaling inhibitors or docetaxel. ARV-7 status was evaluated at baseline with three commercially available assays: AdnaTest Prostate Cancer platform, Clearbridge method, and IBN method. Clinical outcomes at progression were assessed. The primary end point of this study was prevalence of ARV-7 positivity; secondary end points were incidence of ARV-7 positivity, prostate specific antigen (PSA) response rate, PSA progression-free survival (PFS), and overall survival (OS). RESULTS: A total of 102 patients with a median age of 72 years at enrollment participated. Overall, an incidence of ARV-7 positivity of between 14.3% and 33.7% in Asian patients with mCRPC was demonstrated depending on the assay used. Patients found to have ARV-7 positivity at enrollment had a numerically worse PSA PFS compared with ARV-7 negative patients. CONCLUSION: In this study, the incidence of ARV-7 positivity in Asian patients with mCRPC was shown to be similar to the global population. Patients with ARV-7 positivity appear to have more aggressive disease with numerically worse PSA PFS and OS. Further prospective studies are needed to fully characterize the relationship that ARV-7 positivity has on prognosis of Asian patients with mCRPC.

Preclinical evidence for the use of anti-Trop-2 antibody-drug conjugate Sacituzumab govitecan in cerebral metastasized castration-resistant prostate cancer.

PURPOSE: Improved survival rates have been observed in castration-resistant prostate cancer (CRPC) due to advancements in treatment options. However, individuals with brain metastases still have limited therapeutic options and an unfavorable prognosis. Therefore, there is an urgent need to explore new therapeutic avenues, such as antibody-drug conjugates (ADCs), which have demonstrated significant clinical activity against active brain metastases in solid tumors. Our objective was to determine the expression levels of the ADC targets Trop-2 and NECTIN-4 in cerebral metastasized CRPC (mCRPC). METHODS: Immunohistochemical staining of Trop-2 and NECTIN-4 with evaluation of H-score was performed in CRPC brain metastases (n = 31). Additionally, we examined Trop-2 protein expression in prostate cancer cell lines and studied their responsiveness to the anti-Trop-2 ADC Sacituzumab govitecan (SG) in vitro. RESULTS: Our analysis revealed that most patients exhibited moderate to strong Trop-2 expression [n = 27/31 with H-score ≥100, median H-score 220 (IQR 180-280)], while NECTIN-4 was absent in all cerebral metastases. Mechanistically, we demonstrated that the efficacy of SG depends on Trop-2 expression levels in vitro. Overexpression of Trop-2 in Trop-2-negative PC-3 cells led to sensitization to SG, whereas CRISPR-Cas9-mediated knockdown of Trop-2 in Trop-2-expressing DU-145 cells conferred resistance to SG. CONCLUSION: The substantial expression of Trop-2 in cerebral metastases, along with our preclinical in vitro results, supports the efficacy of SG in treating cerebral mCRPC. Thus, our results extend the understanding of the potential of ADCs in prostate cancer treatment and provide an additional treatment strategy for the challenging subset of patients with cerebral metastases.

The efficacy and safety of PARP inhibitors in mCRPC with HRR mutation in second-line treatment: a systematic review and bayesian network meta-analysis.

BACKGROUND: Poly (ADP- ribose) polymerase inhibitors (PARPi) has been increasingly adopted for metastatic castration-resistance prostate cancer (mCRPC) patients with homologous recombination repair deficiency (HRD). However, it is unclear which PARPi is optimal in mCRPC patients with HRD in 2nd -line setting. METHOD: We conducted a systematic review of trials regarding PARPi- based therapies on mCRPC in 2nd -line setting and performed a Bayesian network meta-analysis (NMA). Radiographic progression-free survival (rPFS) was assessed as primary outcome. PSA response and adverse events (AEs) were evaluated as secondary outcomes. Subgroup analyses were performed according to specific genetic mutation. RESULTS: Four RCTs comprised of 1024 patients (763 harbored homologous recombination repair (HRR) mutations) were identified for quantitative analysis. Regarding rPFS, olaparib monotherapy, rucaparib and cediranib plus olaparib showed significant improvement compared with ARAT. Olaparib plus cediranib had the highest surface under cumulative ranking curve (SUCRA) scores (87.5%) for rPFS, followed by rucaparib, olaparib and olaparib plus abiraterone acetate prednisone. For patients with BRCA 1/2 mutations, olaparib associated with the highest probability (98.1%) of improved rPFS. For patients with BRCA-2 mutations, olaparib and olaparib plus cediranib had similar efficacy. However, neither olaparib nor rucaparib showed significant superior effectiveness to androgen receptor-axis-targeted therapy (ARAT) in patients with ATM mutations. For safety, olaparib showed significantly lower ≥ 3 AE rate compared with cediranib plus olaparib (RR: 0.72, 95% CI: 0.51, 0.97), while olaparib plus cediranib was associated with the highest risk of all-grade AE. CONCLUSION: PARPi-based therapy showed considerable efficacy for mCRPC patients with HRD in 2nd -line setting. However, patients should be treated accordingly based on their genetic background as well as the efficacy and safety of the selected regimen. TRIAL REGISTRATION: CRD42023454079.

Rare histologic transformation of a CTNNB1 (ß-catenin) mutated prostate cancer with aggressive clinical course.

BACKGROUND: Catenin (Cadherin-Associated Protein), Beta 1 (CTNNB1) genomic alterations are rare in prostate cancer (PCa). Gain-of-function mutations lead to overexpression of ß-catenin, with consequent hyperactivation of the Wnt/ß-catenin signaling pathway, implicated in PCa progression and treatment resistance. To date, successful targeted treatment options for Wnt/ß-catenin - driven PCa are lacking. METHODS: We report a rare histologic transformation of a CTNNB1 (ß-catenin) mutated metastatic castration resistant prostate cancer (mCRPC), clinically characterized by highly aggressive disease course. We histologically and molecularly characterized the liver metastatic tumor samples, as well as successfully generated patient-derived organoids (PDOs) and patient-derived xenograft (PDX) from a liver metastasis. We used the generated cell models for further molecular characterization and drug response assays. RESULTS: Immunohistochemistry of liver metastatic biopsies and PDX tumor showed lack of expression of typical PCa (e.g., AR, PSA, PSAP, ERG) or neuroendocrine markers (synaptophysin), compatible with double-negative CRPC, but was positive for nuclear ß-catenin expression, keratin 7 and 34ßE12. ERG rearrangement was confirmed by fluorescent in situ hybridization (FISH). Drug response assays confirmed, in line with the clinical disease course, lack of sensitivity to common drugs used in mCRPC (e.g., enzalutamide, docetaxel). The casein kinase 1 (CK1) inhibitor IC261 and the tankyrase 1/2 inhibitor G700-LK showed modest activity. Moreover, despite harbouring a CTNNB1 mutation, PDOs were largely insensitive to SMARCA2/4- targeting PROTAC degraders and inhibitor. CONCLUSIONS: The reported CTNNB1-mutated mCRPC case highlights the potential challenges of double-negative CRPC diagnosis and underlines the relevance of further translational research to enable successful targeted treatment of rare molecular subtypes of mCRPC.