Research autopsy programmes in oncology: shared experience from 14 centres across the world.

While there is a great clinical need to understand the biology of metastatic cancer in order to treat it more effectively, research is hampered by limited sample availability. Research autopsy programmes can crucially advance the field through synchronous, extensive, and high-volume sample collection. However, it remains an underused strategy in translational research. Via an extensive questionnaire, we collected information on the study design, enrolment strategy, study conduct, sample and data management, and challenges and opportunities of research autopsy programmes in oncology worldwide. Fourteen programmes participated in this study. Eight programmes operated 24 h/7 days, resulting in a lower median postmortem interval (time between death and start of the autopsy, 4 h) compared with those operating during working hours (9 h). Most programmes (n = 10) succeeded in collecting all samples within a median of 12 h after death. A large number of tumour sites were sampled during each autopsy (median 15.5 per patient). The median number of samples collected per patient was 58, including different processing methods for tumour samples but also non-tumour tissues and liquid biopsies. Unique biological insights derived from these samples included metastatic progression, treatment resistance, disease heterogeneity, tumour dormancy, interactions with the tumour micro-environment, and tumour representation in liquid biopsies. Tumour patient-derived xenograft (PDX) or organoid (PDO) models were additionally established, allowing for drug discovery and treatment sensitivity assays. Apart from the opportunities and achievements, we also present the challenges related with postmortem sample collections and strategies to overcome them, based on the shared experience of these 14 programmes. Through this work, we hope to increase the transparency of postmortem tissue donation, to encourage and aid the creation of new programmes, and to foster collaborations on these unique sample collections. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

BRCA1 and BRCA2 carriers with breast, ovarian and prostate cancer demonstrate a different pattern of metastatic disease compared with non-carriers: results from a rapid autopsy programme.

AIM: To catalogue and compare the pattern of metastatic disease in germline BRCA1/2 pathogenic mutation carriers and non-carriers with breast, ovarian and prostate cancer from a rapid autopsy programme. METHODS AND RESULTS: The number of metastases in the major body systems and the proportion of participants with metastases were documented in 50 participants (19 germline mutation carriers). Analysis was conducted on the participants' pattern of disease for the different cancers and mutation subgroups. The four commonly affected organ systems were the digestive (liver only) (82%), respiratory (76%), gastrointestinal (65%) and reticuloendothelial (42%). There were significant differences in the pattern of metastatic breast cancer in BRCA1/2 germline carriers compared with non-carriers. Breast cancer carriers had significantly fewer organ systems involved (median n = 3, range = 1-3) compared with non-carriers (median n = 9, range = 1-7) (P = 0.03). BRCA1/2 carriers with ovarian carcinomas had significantly more organ systems with metastatic carcinoma (median n = 10, range = 3-8) than non-carriers (median n = 5, range = 3-5) (P < 0.001). There were no significant differences in the number of involved systems in BRCA2 carriers compared with non-carriers with prostate cancer (P = 1.0). There was an absence of locoregional disease (6.5%) compared with distant disease (93.5%) among the three cancer subtypes (P < 0.001). The majority of metastatic deposits (97%) collected during the autopsy were identified by recent diagnostic imaging. CONCLUSION: Even though a major limitation of this study is that our numbers are small, especially in the breast cancer carrier group, the metastatic patterns of breast and ovarian cancers may be impacted by BRCA1/2 carrier status, suggesting that tumours derived from patients with these mutations use different mechanisms of dissemination. The findings may focus clinical diagnostic imaging for monitoring metastases where whole-body imaging resources are scant.

Impact of concurrent tumour events on the prostate cancer outcomes of germline BRCA2 mutation carriers.

BACKGROUND: Several studies have reported the association of germline BRCA2 (gBRCA2) mutations with poor clinical outcomes in prostate cancer (PCa), but the impact of concurrent somatic events on gBRCA2 carriers survival and disease progression is unknown. PATIENTS AND METHODS: To ascertain the role of frequent somatic genomic alterations and histology subtypes in the outcomes of gBRCA2 mutation carriers and non-carriers, we correlated the tumour characteristics and clinical outcomes of 73 gBRCA2 and 127 non-carriers. Fluorescent in-situ hybridisation and next-generation sequencing were used to detect copy number variations in BRCA2, RB1, MYC and PTEN. Presence of intraductal and cribriform subtypes was also assessed. The independent impact of these events on cause-specific survival (CSS), metastasis-free survival and time to castration-resistant disease was assessed using cox-regression models. RESULTS: Somatic BRCA2-RB1 co-deletion (41% versus 12%, p < 0.001) and MYC amplification (53.4% versus 18.8%, p < 0.001) were enriched in gBRCA2 compared to sporadic tumours. Median CSS from diagnosis of PCa was 9.1 versus 17.6 years in gBRCA2 carriers and non-carriers, respectively (HR 2.12; p = 0.002), Median CSS in gBRCA2 carriers increased to 11.3 and 13.4 years in the absence of BRCA2-RB1 deletion or MYC amplification, respectively. Median CSS of non-carriers decreased to 8 and 2.6 years if BRCA2-RB1 deletion or MYC amplification were detected. CONCLUSIONS: gBRCA2-related prostate tumours are enriched for aggressive genomic features, such as BRCA2-RB1 co-deletion and MYC amplification. The presence or absence of these events modify the outcomes of gBRCA2 carriers.

Multiomic analysis of homologous recombination-deficient end-stage high-grade serous ovarian cancer.

High-grade serous ovarian cancer (HGSC) is frequently characterized by homologous recombination (HR) DNA repair deficiency and, while most such tumors are sensitive to initial treatment, acquired resistance is common. We undertook a multiomics approach to interrogate molecular diversity in end-stage disease, using multiple autopsy samples collected from 15 women with HR-deficient HGSC. Patients had polyclonal disease, and several resistance mechanisms were identified within most patients, including reversion mutations and HR restoration by other means. We also observed frequent whole-genome duplication and global changes in immune composition with evidence of immune escape. This analysis highlights diverse evolutionary changes within HGSC that evade therapy and ultimately overwhelm individual patients.

Targeting MDM4 as a Novel Therapeutic Approach in Prostate Cancer Independent of p53 Status.

Metastatic prostate cancer is a lethal disease in patients incapable of responding to therapeutic interventions. Invasive prostate cancer spread is caused by failure of the normal anti-cancer defense systems that are controlled by the tumour suppressor protein, p53. Upon mutation, p53 malfunctions. Therapeutic strategies to directly re-empower the growth-restrictive capacities of p53 in cancers have largely been unsuccessful, frequently because of a failure to discriminate responses in diseased and healthy tissues. Our studies sought alternative prostate cancer drivers, intending to uncover new treatment targets. We discovered the oncogenic potency of MDM4 in prostate cancer cells, both in the presence and absence of p53 and also its mutation. We uncovered that sustained depletion of MDM4 is growth inhibitory in prostate cancer cells, involving either apoptosis or senescence, depending on the cell and genetic context. We identified that the potency of MDM4 targeting could be potentiated in prostate cancers with mutant p53 through the addition of a first-in-class small molecule drug that was selected as a p53 reactivator and has the capacity to elevate oxidative stress in cancer cells to drive their death.

Novel Germline Mutations in a Cohort of Men with Familial Prostate Cancer.

Background: Germline mutations in BRCA2 are associated with aggressive prostate cancer. Additional information regarding the clinical phenotype of germline pathogenic variants in other prostate cancer predisposition genes is required. Clinical testing has been limited by evidence, further restricting knowledge of variants that contribute to prostate cancer development. Objective: Prostate cancer patients who were first- and second-degree relatives from multi-case prostate cancer families underwent a gene panel screen to identify novel (non-BRCA) germline pathogenic variants in cancer predisposition genes and define clinical phenotypes associated with each gene. Methods: The germline genomic DNA (gDNA) of 94 index cases with verified prostate cancer from families with a minimum of two verified prostate cancer cases was screened with an 84-cancer-gene panel. Families were recruited for multi-case breast/ovarian cancer (n = 66), or multi-case prostate cancer (n = 28). Prostate cancer characteristics associated with each gene were compared with prostate cancer cases of confirmed non-mutation carriers (BRCAX), also from multi-case prostate cancer families (n = 111), and with data from the Prostate Cancer Outcomes Registry (PCOR). Results: Ninety-four prostate cancer index cases underwent gene panel testing; twenty-two index cases (22/94; 23%) were found to carry a class 4-5 (C4/5) variant. Six of twenty-two (27%) variants were not clinically notifiable, and seven of twenty-two (31.8%) variants were in BRCA1/2 genes. Nine of twenty-two (40.9%) index cases had variants identified in ATM (n = 4), CHEK2 (n = 2) and HOXB13G84 (n = 3); gDNA for all relatives of these nine cases was screened for the corresponding familial variant. The final cohort comprised 15 confirmed germline mutation carriers with prostate cancer (ATM n = 9, CHEK2 n = 2, HOXB13G84 n = 4). ATM and CHEK2-associated cancers were D'Amico intermediate or high risk, comparable to our previously published BRCA2 and BRCAX prostate cancer cohort. HOXB13G84 carriers demonstrated low- to intermediate-risk prostate cancer. In the BRCAX cohort, 53.2% of subjects demonstrated high-risk disease compared with 25% of the PCOR cohort. Conclusions:ATM and CHEK2 germline mutation carriers and the BRCAX (confirmed non-mutation carriers) cohort demonstrated high risk disease compared with the general population. Targeted genetic testing will help identify men at greater risk of prostate-cancer-specific mortality. Data correlating rare variants with clinical phenotype and familial predisposition will strengthen the clinical validity and utility of these results and establish these variants as significant in prostate cancer detection and management.

Novel germline mutations for active surveillance and imaging strategies in prostate cancer.

PURPOSE OF REVIEW: This review highlights the emerging role of genetics-lead medicine (GLM) in prostate cancer. We describe the benefits of GLM integration into prostate cancer screening, diagnosis and management. Imaging techniques enhancing prostate cancer detection are advancing concurrently, facilitating strategic active surveillance protocols for appropriately selected patients. We aim to improve clinician awareness of the role of GLM in current and future practice. RECENT FINDINGS: We explore recent literature advancing the role of GLM in prostate cancer detection and management, particularly as this coexists with the development of imaging technology. Our current understanding of germline mutations implicated in familial prostate cancer development is summarized. We describe how these developments are being utilized to inform screening, surveillance and the development of novel therapies. We summarize current guidelines and explore factors inhibiting optimal implementation of recommendations in clinical practice. SUMMARY: Integration and further development of genetics-lead medicine in the detection, surveillance and management of prostate cancer will improve clinical outcomes for men at risk of aggressive disease as a result of familial predispositions to prostate cancer. This review summarizes the pertinent developments in the field including improving clinician awareness to facilitate implantation of these strategies into current clinical practice.

Tumor immune microenvironment of primary prostate cancer with and without germline mutations in homologous recombination repair genes.

BACKGROUND: Aberrations in homologous recombination repair (HRR) genes are emerging as important biomarkers for personalized treatment in prostate cancer (PCa). HRR deficiency (HRD) could affect the tumor immune microenvironment (TIME), potentially contributing to differential responses to poly ADP-ribose polymerase (PARP) inhibitors and immune checkpoint inhibitors. Spatial distribution of immune cells in a range of cancers identifies novel disease subtypes and is related to prognosis. In this study we aimed to determine the differences in the TIME of PCa with and without germline (g) HRR mutations. METHODS: We performed gene expression analysis, multiplex immunohistochemistry of T and B cells and quantitative spatial analysis of PCa samples from 36 patients with gHRD and 26 patients with sporadic PCa. Samples were archival tumor tissue from radical prostatectomies with the exception of one biopsy. Results were validated in several independent cohorts. RESULTS: Although the composition of the T cell and B cells was similar in the tumor areas of gHRD-mutated and sporadic tumors, the spatial profiles differed between these cohorts. We describe two T-cell spatial profiles across primary PCa, a clustered immune spatial (CIS) profile characterized by dense clusters of CD4+ T cells closely interacting with PD-L1+ cells, and a free immune spatial (FIS) profile of CD8+ cells in close proximity to tumor cells. gHRD tumors had a more T-cell inflamed microenvironment than sporadic tumors. The CIS profile was mainly observed in sporadic tumors, whereas a FIS profile was enriched in gHRD tumors. A FIS profile was associated with lower Gleason scores, smaller tumors and longer time to biochemical recurrence and metastasis. CONCLUSIONS: gHRD-mutated tumors have a distinct immune microenvironment compared with sporadic tumors. Spatial profiling of T-cells provides additional information beyond T-cell density and is associated with time to biochemical recurrence, time to metastasis, tumor size and Gleason scores.

Value of the loss of heterozygosity to BRCA1 variant classification.

At least 10% of the BRCA1/2 tests identify variants of uncertain significance (VUS) while the distinction between pathogenic variants (PV) and benign variants (BV) remains particularly challenging. As a typical tumor suppressor gene, the inactivation of the second wild-type (WT) BRCA1 allele is expected to trigger cancer initiation. Loss of heterozygosity (LOH) of the WT allele is the most frequent mechanism for the BRCA1 biallelic inactivation. To evaluate if LOH can be an effective predictor of BRCA1 variant pathogenicity, we carried out LOH analysis on DNA extracted from 90 breast and seven ovary tumors diagnosed in 27 benign and 55 pathogenic variant carriers. Further analyses were conducted in tumors with PVs yet without loss of the WT allele: BRCA1 promoter hypermethylation, next-generation sequencing (NGS) of BRCA1/2, and BRCAness score. Ninety-seven tumor samples were analyzed from 26 different BRCA1 variants. A relatively stable pattern of LOH (65.4%) of WT allele for PV tumors was observed, while the allelic balance (63%) or loss of variant allele (15%) was generally seen for carriers of BV. LOH data is a useful complementary argument for BRCA1 variant classification.

Weight is More Informative than Body Mass Index for Predicting Postmenopausal Breast Cancer Risk: Prospective Family Study Cohort (ProF-SC).

We considered whether weight is more informative than body mass index (BMI) = weight/height2 when predicting breast cancer risk for postmenopausal women, and if the weight association differs by underlying familial risk. We studied 6,761 women postmenopausal at baseline with a wide range of familial risk from 2,364 families in the Prospective Family Study Cohort. Participants were followed for on average 11.45 years and there were 416 incident breast cancers. We used Cox regression to estimate risk associations with log-transformed weight and BMI after adjusting for underlying familial risk. We compared model fits using the Akaike information criterion (AIC) and nested models using the likelihood ratio test. The AIC for the weight-only model was 6.22 units lower than for the BMI-only model, and the log risk gradient was 23% greater. Adding BMI or height to weight did not improve fit (ΔAIC = 0.90 and 0.83, respectively; both P = 0.3). Conversely, adding weight to BMI or height gave better fits (ΔAIC = 5.32 and 11.64; P = 0.007 and 0.0002, respectively). Adding height improved only the BMI model (ΔAIC = 5.47; P = 0.006). There was no evidence that the BMI or weight associations differed by underlying familial risk (P > 0.2). Weight is more informative than BMI for predicting breast cancer risk, consistent with nonadipose as well as adipose tissue being etiologically relevant. The independent but multiplicative associations of weight and familial risk suggest that, in terms of absolute breast cancer risk, the association with weight is more important the greater a woman's underlying familial risk. PREVENTION RELEVANCE: Our results suggest that the relationship between BMI and breast cancer could be due to a relationship between weight and breast cancer, downgraded by inappropriately adjusting for height; potential importance of anthropometric measures other than total body fat; breast cancer risk associations with BMI and weight are across a continuum.

Risks of breast and ovarian cancer for women harboring pathogenic missense variants in BRCA1 and BRCA2 compared with those harboring protein truncating variants.

PURPOSE: Germline genetic testing for BRCA1 and BRCA2 variants has been a part of clinical practice for >2 decades. However, no studies have compared the cancer risks associated with missense pathogenic variants (PVs) with those associated with protein truncating (PTC) variants. METHODS: We collected 582 informative pedigrees segregating 1 of 28 missense PVs in BRCA1 and 153 pedigrees segregating 1 of 12 missense PVs in BRCA2. We analyzed 324 pedigrees with PTC variants in BRCA1 and 214 pedigrees with PTC variants in BRCA2. Cancer risks were estimated using modified segregation analysis. RESULTS: Estimated breast cancer risks were markedly lower for women aged >50 years carrying BRCA1 missense PVs than for the women carrying BRCA1 PTC variants (hazard ratio [HR] = 3.9 [2.4-6.2] for PVs vs 12.8 [5.7-28.7] for PTC variants; P = .01), particularly for missense PVs in the BRCA1 C-terminal domain (HR = 2.8 [1.4-5.6]; P = .005). In case of BRCA2, for women aged >50 years, the HR was 3.9 (2.0-7.2) for those heterozygous for missense PVs compared with 7.0 (3.3-14.7) for those harboring PTC variants. BRCA1 p.[Cys64Arg] and BRCA2 p.[Trp2626Cys] were associated with particularly low risks of breast cancer compared with other PVs. CONCLUSION: These results have important implications for the counseling of at-risk women who harbor missense PVs in the BRCA1/2 genes.

The MURAL collection of prostate cancer patient-derived xenografts enables discovery through preclinical models of uro-oncology.

Preclinical testing is a crucial step in evaluating cancer therapeutics. We aimed to establish a significant resource of patient-derived xenografts (PDXs) of prostate cancer for rapid and systematic evaluation of candidate therapies. The PDX collection comprises 59 tumors collected from 30 patients between 2012-2020, coinciding with availability of abiraterone and enzalutamide. The PDXs represent the clinico-pathological and genomic spectrum of prostate cancer, from treatment-naïve primary tumors to castration-resistant metastases. Inter- and intra-tumor heterogeneity in adenocarcinoma and neuroendocrine phenotypes is evident from bulk and single-cell RNA sequencing data. Organoids can be cultured from PDXs, providing further capabilities for preclinical studies. Using a 1 x 1 x 1 design, we rapidly identify tumors with exceptional responses to combination treatments. To govern the distribution of PDXs, we formed the Melbourne Urological Research Alliance (MURAL). This PDX collection is a substantial resource, expanding the capacity to test and prioritize effective treatments for prospective clinical trials in prostate cancer.

Evolution of late-stage metastatic melanoma is dominated by aneuploidy and whole genome doubling.

Although melanoma is initiated by acquisition of point mutations and limited focal copy number alterations in melanocytes-of-origin, the nature of genetic changes that characterise lethal metastatic disease is poorly understood. Here, we analyze the evolution of human melanoma progressing from early to late disease in 13 patients by sampling their tumours at multiple sites and times. Whole exome and genome sequencing data from 88 tumour samples reveals only limited gain of point mutations generally, with net mutational loss in some metastases. In contrast, melanoma evolution is dominated by whole genome doubling and large-scale aneuploidy, in which widespread loss of heterozygosity sculpts the burden of point mutations, neoantigens and structural variants even in treatment-naïve and primary cutaneous melanomas in some patients. These results imply that dysregulation of genomic integrity is a key driver of selective clonal advantage during melanoma progression.

Association between BRCA2 alterations and intraductal and cribriform histologies in prostate cancer.

BACKGROUND: Intraductal (IDC) and cribriform (CRIB) histologies in prostate cancer have been associated with germline BRCA2 (gBRCA2) mutations in small retrospective series, leading to the recommendation of genetic testing for patients with IDC in the primary tumour. PATIENTS AND METHODS: To examine the association of gBRCA2 mutations and other tumour molecular features with IDC and/or cribriform (CRIB) histologies, we conducted a case-control study in which primary prostate tumours from 58 gBRCA2 carriers were matched (1:2) by Gleason Grade Group and specimen type to 116 non-carriers. Presence/absence of IDC and CRIB morphologies was established by two expert uropathologists blinded to gBRCA2 status. Fluorescent in-situ hybridization (FISH) and next-generation sequencing (NGS) were used to detect BRCA2 alterations, PTEN deletions and TMPRSS2-ERG fusions. Chi-squared tests were used to compare the frequency of IDC and CRIB in gBRCA2 carriers and controls and to assess associations with other variables. Logistic regression models were constructed to identify independent factors associated with both histology patterns. RESULTS: No significant differences between gBRCA2 carriers and non-carriers were observed in the prevalence of IDC (36% gBRCA2 versus 50% non-carriers, p = 0.085) or CRIB (53% gBRCA2 versus 43% non-carriers p = 0.197) patterns. However, IDC histology was independently associated with bi-allelic BRCA2 alterations (OR 4.3, 95%CI 1.1-16.2) and PTEN homozygous loss (OR 5.2, 95%CI 2.1-13.1). CRIB morphology was also independently associated with bi-allelic BRCA2 alterations (OR 5.6, 95%CI 1.7-19.3). CONCLUSIONS: While we found no association between gBRCA2 mutations and IDC or CRIB histologies, bi-allelic BRCA2 loss in primary prostate tumours was significantly associated with both variant morphologies, independently of other clinical-pathologic factors.

Multiple ABCB1 transcriptional fusions in drug resistant high-grade serous ovarian and breast cancer.

ABCB1 encodes Multidrug Resistance protein (MDR1), an ATP-binding cassette member involved in the cellular efflux of chemotherapeutic drugs. Here we report that ovarian and breast samples from chemotherapy treated patients are positive for multiple transcriptional fusions involving ABCB1, placing it under the control of a strong promoter while leaving its open reading frame intact. We identified 15 different transcriptional fusion partners involving ABCB1, as well as patients with multiple distinct fusion events. The partner gene selected depended on its structure, promoter strength, and chromosomal proximity to ABCB1. Fusion positivity was strongly associated with the number of lines of MDR1-substrate chemotherapy given. MDR1 inhibition in a fusion positive ovarian cancer cell line increased sensitivity to paclitaxel more than 50-fold. Convergent evolution of ABCB1 fusion is therefore frequent in chemotherapy resistant recurrent ovarian cancer. As most currently approved PARP inhibitors (PARPi) are MDR1 substrates, prior chemotherapy may precondition resistance to PARPi.

Patient-derived Models of Abiraterone- and Enzalutamide-resistant Prostate Cancer Reveal Sensitivity to Ribosome-directed Therapy.

BACKGROUND: The intractability of castration-resistant prostate cancer (CRPC) is exacerbated by tumour heterogeneity, including diverse alterations to the androgen receptor (AR) axis and AR-independent phenotypes. The availability of additional models encompassing this heterogeneity would facilitate the identification of more effective therapies for CRPC. OBJECTIVE: To discover therapeutic strategies by exploiting patient-derived models that exemplify the heterogeneity of CRPC. DESIGN, SETTING, AND PARTICIPANTS: Four new patient-derived xenografts (PDXs) were established from independent metastases of two patients and characterised using integrative genomics. A panel of rationally selected drugs was tested using an innovative ex vivo PDX culture system. INTERVENTION: The following drugs were evaluated: AR signalling inhibitors (enzalutamide and galeterone), a PARP inhibitor (talazoparib), a chemotherapeutic (cisplatin), a CDK4/6 inhibitor (ribociclib), bromodomain and extraterminal (BET) protein inhibitors (iBET151 and JQ1), and inhibitors of ribosome biogenesis/function (RNA polymerase I inhibitor CX-5461 and pan-PIM kinase inhibitor CX-6258). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Drug efficacy in ex vivo cultures of PDX tissues was evaluated using immunohistochemistry for Ki67 and cleaved caspase-3 levels. Candidate drugs were also tested for antitumour efficacy in vivo, with tumour volume being the primary endpoint. Two-tailed t tests were used to compare drug and control treatments. RESULTS AND LIMITATIONS: Integrative genomics revealed that the new PDXs exhibited heterogeneous mechanisms of resistance, including known and novel AR mutations, genomic structural rearrangements of the AR gene, and a neuroendocrine-like AR-null phenotype. Despite their heterogeneity, all models were sensitive to the combination of ribosome-targeting agents CX-5461 and CX-6258. CONCLUSIONS: This study demonstrates that ribosome-targeting drugs may be effective against diverse CRPC subtypes including AR-null disease, and highlights the potential of contemporary patient-derived models to prioritise treatment strategies for clinical translation. PATIENT SUMMARY: Diverse types of therapy-resistant prostate cancers are sensitive to a new combination of drugs that inhibit protein synthesis pathways in cancer cells.

Clinical Outcome of Prostate Cancer Patients with Germline DNA Repair Mutations: Retrospective Analysis from an International Study.

BACKGROUND: Germline DNA damage repair gene mutation (gDDRm) is found in >10% of metastatic prostate cancer (mPC). Their prognostic and predictive impact relating to standard therapies is unclear. OBJECTIVE: To determine whether gDDRm status impacts benefit from established therapies in mPC. DESIGN, SETTING, AND PARTICIPANTS: This is a retrospective, international, observational study. Medical records were reviewed for 390 mPC patients with known gDDRm status. All 372 patients from Royal Marsden (UK), Weill-Cornell (NY), and University of Washington (WA) were previously included in a prevalence study (Pritchard, NEJM 2016); the remaining 18 were gBRCA1/2m carriers, from the kConFab consortium, Australia. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Response rate (RR), progression-free survival (PFS), and overall survival (OS) data were collected. To account for potential differences between cohorts, a mixed-effect model (Weibull distribution) with random intercept per cohort was used. RESULTS AND LIMITATIONS: The gDDRm status was known for all 390 patients (60 carriers of gDDRm [gDDRm+], including 37 gBRCA2m, and 330 cases not found to carry gDDRm [gDDRm-]); 74% and 69% were treated with docetaxel and abiraterone/enzalutamide, respectively, and 36% received PARP inhibitors (PARPi) and/or platinum. Median OS from castration resistance was similar among groups (3.2 vs 3.0 yr, p=0.73). Median docetaxel PFS for gDDRm+ (6.8 mo) was not significantly different from that for gDDRm- (5.1 mo), and RRs were similar (gDDRm+=61%; gDDRm-=54%). There were no significant differences in median PFS and RR on first-line abiraterone/enzalutamide (gDDRm+=8.3 mo, gDDRm-=8.3 mo; gDDRm+=46%, gDDRm-=56%). Interaction test for PARPi/platinum and gDDRm+ resulted in an OS adjusted hazard ratio of 0.59 (95% confidence interval 0.28-1.25; p=0.17). Results are limited by the retrospective nature of the analysis. CONCLUSIONS: mPC patients with gDDRm appeared to benefit from standard therapies similarly to the overall population; prospective studies are ongoing to investigate the impact of PARPi/platinum. PATIENT SUMMARY: Patients with inherited DNA repair mutations benefit from standard therapies similarly to other metastatic prostate cancer patients.

Intraductal carcinoma of the prostate can evade androgen deprivation, with emergence of castrate-tolerant cells.

OBJECTIVE: To determine the relevance of intraductal carcinoma of the prostate (IDC-P) in advanced prostate cancer by first examining whether IDC-P was originally present in patients who later developed advanced prostate cancer and then using patient-derived xenografts (PDXs) to investigate the response of IDC-P to androgen deprivation therapy (ADT). MATERIALS AND METHODS: We conducted a retrospective pathology review of IDC-P in primary prostate biopsy or surgery specimens from 38 men who subsequently developed advanced prostate cancer. Overall survival was calculated using the Kaplan-Meier method. To demonstrate the response of IDC-P to ADT, we established PDXs from seven patients with familial and/or high-risk sporadic prostate cancer. After castration and testosterone restoration of host mice, we measured the volume and proliferation of IDC-P within PDX grafts. RESULTS: We found that IDC-P was a prominent feature in the primary prostate specimens, present in 63% of specimens and often co-existing with poorly differentiated adenocarcinoma. Overall survival was similar in patients with or without IDC-P. In the PDXs from all seven patients, IDC-P was identified and present at a similar volume to adenocarcinoma. Residual IDC-P lesions persisted after host castration and, similar to castrate-tolerant adenocarcinoma, testosterone restoration led to tumour regeneration. CONCLUSION: The study showed that IDC-P is prevalent in aggressive prostate cancer and contains cells that can withstand androgen deprivation. Thus, IDC-P appears functionally relevant in advanced prostate cancer. The presence of IDC-P may be a trigger to develop innovative clinical management plans.