IL-23 secreted by myeloid cells drives castration-resistant prostate cancer.

Patients with prostate cancer frequently show resistance to androgen-deprivation therapy, a condition known as castration-resistant prostate cancer (CRPC). Acquiring a better understanding of the mechanisms that control the development of CRPC remains an unmet clinical need. The well-established dependency of cancer cells on the tumour microenvironment indicates that the microenvironment might control the emergence of CRPC. Here we identify IL-23 produced by myeloid-derived suppressor cells (MDSCs) as a driver of CRPC in mice and patients with CRPC. Mechanistically, IL-23 secreted by MDSCs can activate the androgen receptor pathway in prostate tumour cells, promoting cell survival and proliferation in androgen-deprived conditions. Intra-tumour MDSC infiltration and IL-23 concentration are increased in blood and tumour samples from patients with CRPC. Antibody-mediated inactivation of IL-23 restored sensitivity to androgen-deprivation therapy in mice. Taken together, these results reveal that MDSCs promote CRPC by acting in a non-cell autonomous manner. Treatments that block IL-23 can oppose MDSC-mediated resistance to castration in prostate cancer and synergize with standard therapies.

Adjuvant chemotherapy in upper tract urothelial carcinoma (the POUT trial): a phase 3, open-label, randomised controlled trial.

BACKGROUND: Urothelial carcinomas of the upper urinary tract (UTUCs) are rare, with poorer stage-for-stage prognosis than urothelial carcinomas of the urinary bladder. No international consensus exists on the benefit of adjuvant chemotherapy for patients with UTUCs after nephroureterectomy with curative intent. The POUT (Peri-Operative chemotherapy versus sUrveillance in upper Tract urothelial cancer) trial aimed to assess the efficacy of systemic platinum-based chemotherapy in patients with UTUCs. METHODS: We did a phase 3, open-label, randomised controlled trial at 71 hospitals in the UK. We recruited patients with UTUC after nephroureterectomy staged as either pT2-T4 pN0-N3 M0 or pTany N1-3 M0. We randomly allocated participants centrally (1:1) to either surveillance or four 21-day cycles of chemotherapy, using a minimisation algorithm with a random element. Chemotherapy was either cisplatin (70 mg/m2) or carboplatin (area under the curve [AUC]4·5/AUC5, for glomerular filtration rate <50 mL/min only) administered intravenously on day 1 and gemcitabine (1000 mg/m2) administered intravenously on days 1 and 8; chemotherapy was initiated within 90 days of surgery. Follow-up included standard cystoscopic, radiological, and clinical assessments. The primary endpoint was disease-free survival analysed by intention to treat with a Peto-Haybittle stopping rule for (in)efficacy. The trial is registered with ClinicalTrials.gov, NCT01993979. A preplanned interim analysis met the efficacy criterion for early closure after recruitment of 261 participants. FINDINGS: Between June 19, 2012, and Nov 8, 2017, we enrolled 261 participants from 57 of 71 open study sites. 132 patients were assigned chemotherapy and 129 surveillance. One participant allocated chemotherapy withdrew consent for data use after randomisation and was excluded from analyses. Adjuvant chemotherapy significantly improved disease-free survival (hazard ratio 0·45, 95% CI 0·30-0·68; p=0·0001) at a median follow-up of 30·3 months (IQR 18·0-47·5). 3-year event-free estimates were 71% (95% CI 61-78) and 46% (36-56) for chemotherapy and surveillance, respectively. 55 (44%) of 126 participants who started chemotherapy had acute grade 3 or worse treatment-emergent adverse events, which accorded with frequently reported events for the chemotherapy regimen. Five (4%) of 129 patients managed by surveillance had acute grade 3 or worse emergent adverse events. No treatment-related deaths were reported. INTERPRETATION: Gemcitabine-platinum combination chemotherapy initiated within 90 days after nephroureterectomy significantly improved disease-free survival in patients with locally advanced UTUC. Adjuvant platinum-based chemotherapy should be considered a new standard of care after nephroureterectomy for this patient population. FUNDING: Cancer Research UK.

Radiological evaluation of malignant pleural mesothelioma - defining distant metastatic disease.

BACKGROUND: Malignant pleural mesothelioma (MPM) is traditionally characterized by local destructive spread of the pleura and surrounding tissues. Patient outcomes in MPM with distant metastatic dissemination are lacking. METHODS: In this retrospective study, we reviewed a cohort of 164 MPM patients referred to a Phase I trials unit, aiming to describe identified metastatic sites, and correlate with clinical outcomes. RESULTS: 67% of patients were diagnosed with distant metastatic disease with a high incidence of bone (19%), visceral (14%), contralateral lung (35%) and peritoneal metastases (22%). Peritoneal metastases were more likely in epithelioid versus biphasic/ sarcomatoid MPM (p = 0.015). Overall survival was 23.8 months with no statistical difference in survival between those with distant metastases and those without. CONCLUSIONS: This report highlights the frequency of distant metastases and encourages further radiological investigations in the presence of symptoms. In particular, given the relatively high incidence of bone metastases, bone imaging should be considered in advanced MPM clinical workflow and trial protocols. The presence of distant metastases does not appear to have prognostic implications under existing treatment paradigms. This cohort of MPM patients gives an indication of patterns of metastatic spread that are likely to become prevalent as prognosis improves with emerging treatment paradigms.

Diffusion-weighted MRI in Advanced Epithelial Ovarian Cancer: Apparent Diffusion Coefficient as a Response Marker.

Background Treatment of advanced epithelial ovarian cancer results in a relapse rate of 75%. Early markers of response would enable optimization of management and improved outcome in both primary and recurrent disease. Purpose To assess the apparent diffusion coefficient (ADC), derived from diffusion-weighted MRI, as an indicator of response, progression-free survival (PFS), and overall survival. Materials and Methods This prospective multicenter trial (from 2012-2016) recruited participants with stage III or IV ovarian, primary peritoneal, or fallopian tube cancer (newly diagnosed, cohort one; relapsed, cohort two) scheduled for platinum-based chemotherapy, with interval debulking surgery in cohort one. Cohort one underwent two baseline MRI examinations separated by 0-7 days to assess ADC repeatability; an additional MRI was performed after three treatment cycles. Cohort two underwent imaging at baseline and after one and three treatment cycles. ADC changes in responders and nonresponders were compared (Wilcoxon rank sum tests). PFS and overall survival were assessed by using a multivariable Cox model. Results A total of 125 participants (median age, 63.3 years [interquartile range, 57.0-70.7 years]; 125 women; cohort one, n = 47; cohort two, n = 78) were included. Baseline ADC (range, 77-258 × 10-5mm2s-1) was repeatable (upper and lower 95% limits of agreement of 12 × 10-5mm2s-1 [95% confidence interval {CI}: 6 × 10-5mm2s-1 to 18 × 10-5mm2s-1] and -15 × 10-5mm2s-1 [95% CI: -21 × 10-5mm2s-1 to -9 × 10-5mm2s-1]). ADC increased in 47% of cohort two after one treatment cycle, and in 58% and 53% of cohorts one and two, respectively, after three cycles. Percentage change from baseline differed between responders and nonresponders after three cycles (16.6% vs 3.9%; P = .02 [biochemical response definition]; 19.0% vs 6.2%; P = .04 [radiologic definition]). ADC increase after one cycle was associated with longer PFS in cohort two (adjusted hazard ratio, 0.86; 95% CI: 0.75, 0.98; P = .03). ADC change was not indicative of overall survival for either cohort. Conclusion After three cycles of platinum-based chemotherapy, apparent diffusion coefficient (ADC) changes are indicative of response. After one treatment cycle, increased ADC is indicative of improved progression-free survival in relapsed disease. Published under a CC BY 4.0 license. Online supplemental material is available for this article.

The Context of Sexual Risk Behaviour Among Men Who Have Sex with Men Seeking PrEP, and the Impact of PrEP on Sexual Behaviour.

There are still important gaps in our understanding of how people will incorporate PrEP into their existing HIV prevention strategies. In this paper, we explore how PrEP use impacted existing sexual risk behaviours and risk reduction strategies using qualitative data from the PROUD study. From February 2014 to January 2016, we conducted 41 in-depth interviews with gay, bisexual and other men who have sex with men (GBMSM) enrolled in the PROUD PrEP study at sexual health clinics in England. The interviews were conducted in English and were audio-recorded. The recordings were transcribed, coded and analysed using framework analysis. In the interviews, we explored participants' sexual behaviour before joining the study and among those using or who had used PrEP, changes to sexual behaviour after starting PrEP. Participants described the risk behaviour and management strategies before using PrEP, which included irregular condom use, sero-sorting, and strategic positioning. Participants described their sexual risk taking before initiating PrEP in the context of the sexualised use of drugs, geographical spaces linked with higher risk sexual norms, and digitised sexual networking, as well as problematic psychological factors that exacerbated risk taking. The findings highlight that in the main, individuals who were already having frequent condomless sex, added PrEP to the existing range of risk management strategies, influencing the boundaries of the 'rules' for some but not all. While approximately half the participants reduced other risk reduction strategies after starting PrEP, the other half did not alter their behaviours. PrEP provided an additional HIV prevention option to a cohort of GBMSM at high risk of HIV due to inconsistent use of other prevention options. In summary, PrEP provides a critical and necessary additional HIV prevention option that individuals can add to existing strategies in order to enhance protection, at least from HIV. As a daily pill, PrEP offers protection in the context of the sex cultures associated with sexualised drug use, digitised sexual applications and shifting social norms around sexual fulfilment and risk taking. PrEP can offer short or longer-term options for individuals as their sexual desires change over their life course offering protection from HIV during periods of heightened risk. PrEP should not be perceived or positioned in opposition to the existing HIV prevention toolkit, but rather as additive and as a tool that can and is having a substantial impact on HIV.

Pre-exposure prophylaxis to prevent the acquisition of HIV-1 infection (PROUD): effectiveness results from the pilot phase of a pragmatic open-label randomised trial.

BACKGROUND: Randomised placebo-controlled trials have shown that daily oral pre-exposure prophylaxis (PrEP) with tenofovir-emtricitabine reduces the risk of HIV infection. However, this benefit could be counteracted by risk compensation in users of PrEP. We did the PROUD study to assess this effect. METHODS: PROUD is an open-label randomised trial done at 13 sexual health clinics in England. We enrolled HIV-negative gay and other men who have sex with men who had had anal intercourse without a condom in the previous 90 days. Participants were randomly assigned (1:1) to receive daily combined tenofovir disoproxil fumarate (245 mg) and emtricitabine (200 mg) either immediately or after a deferral period of 1 year. Randomisation was done via web-based access to a central computer-generated list with variable block sizes (stratified by clinical site). Follow-up was quarterly. The primary outcomes for the pilot phase were time to accrue 500 participants and retention; secondary outcomes included incident HIV infection during the deferral period, safety, adherence, and risk compensation. The trial is registered with ISRCTN (number ISRCTN94465371) and ClinicalTrials.gov (NCT02065986). FINDINGS: We enrolled 544 participants (275 in the immediate group, 269 in the deferred group) between Nov 29, 2012, and April 30, 2014. Based on early evidence of effectiveness, the trial steering committee recommended on Oct 13, 2014, that all deferred participants be offered PrEP. Follow-up for HIV incidence was complete for 243 (94%) of 259 patient-years in the immediate group versus 222 (90%) of 245 patient-years in the deferred group. Three HIV infections occurred in the immediate group (1·2/100 person-years) versus 20 in the deferred group (9·0/100 person-years) despite 174 prescriptions of post-exposure prophylaxis in the deferred group (relative reduction 86%, 90% CI 64-96, p=0·0001; absolute difference 7·8/100 person-years, 90% CI 4·3-11·3). 13 men (90% CI 9-23) in a similar population would need access to 1 year of PrEP to avert one HIV infection. We recorded no serious adverse drug reactions; 28 adverse events, most commonly nausea, headache, and arthralgia, resulted in interruption of PrEp. We detected no difference in the occurrence of sexually transmitted infections, including rectal gonorrhoea and chlamydia, between groups, despite a suggestion of risk compensation among some PrEP recipients. INTERPRETATION: In this high incidence population, daily tenofovir-emtricitabine conferred even higher protection against HIV than in placebo-controlled trials, refuting concerns that effectiveness would be less in a real-world setting. There was no evidence of an increase in other sexually transmitted infections. Our findings strongly support the addition of PrEP to the standard of prevention for men who have sex with men at risk of HIV infection. FUNDING: MRC Clinical Trials Unit at UCL, Public Health England, and Gilead Sciences.

The virological durability of first-line ART among HIV-positive adult patients in resource limited settings without virological monitoring: a retrospective analysis of DART trial data.

BACKGROUND: Few low-income countries have virological monitoring widely available. We estimated the virological durability of first-line antiretroviral therapy (ART) after five years of follow-up among adult Ugandan and Zimbabwean patients in the DART study, in which virological assays were conducted retrospectively. METHODS: DART compared clinically driven monitoring with/without routine CD4 measurement. Annual plasma viral load was measured on 1,762 patients. Analytical weights were calculated based on the inverse probability of sampling. Time to virological failure, defined as the first viral load measurement ≥200 copies/mL after 48 weeks of ART, was analysed using Kaplan-Meier plots and Cox regression models. RESULTS: Overall, 65% of DART trial patients were female. Patients initiated first-line ART at a median (interquartile range; IQR) age of 37 (32-42) and with a median CD4 cell count of 86 (32-140). After 240 weeks of ART, patients initiating dual-class nucleoside reverse-transcriptase inhibitor (NRTI) -non-nucleoside reverse-transcriptase (NNRTI) regimens containing nevirapine + zidovudine + lamivudine had a lower incidence of virological failure than patients on triple-NRTI regimens containing tenofovir + zidovudine + lamivudine (21% vs 40%; hazard ratio (HR) =0.48, 95% CI:0.38-0.62; p < 0.0001). In multivariate analyses, female patients (HR = 0.79, 95% CI: 0.65-0.95; p = 0.02), older patients (HR = 0.73 per 10 years, 95% CI: 0.64-0.84; p < 0.0001) and patients with a higher pre-ART CD4 cell count (HR = 0.64 per 100 cells/mm3, 95% CI: 0.54-0.75; p < 0.0001) had a lower incidence of virological failure after adjusting for adherence to ART. No difference in failure rate between the two randomised monitoring strategies was observed (p= 0.25). CONCLUSIONS: The long-term durability of virological suppression on dual-class NRTI-NNRTI first-line ART without virological monitoring is remarkable and is enabled by high-quality clinical management and a consistent drug supply. To achieve higher rates of virological suppression viral-load-informed differentiated care may be required. TRIAL REGISTRATION: Prospectively registered on 18/10/2000 as ISRCTN13968779 .

Low frequency of genotypic resistance in HIV-1-infected patients failing an atazanavir-containing regimen: a clinical cohort study.

OBJECTIVES: To determine protease mutations that develop at viral failure for protease inhibitor (PI)-naive patients on a regimen containing the PI atazanavir. METHODS: Resistance tests on patients failing atazanavir, conducted as part of routine clinical care in a multicentre observational study, were randomly matched by subtype to resistance tests from PI-naive controls to account for natural polymorphisms. Mutations from the consensus B sequence across the protease region were analysed for association and defined using the IAS-USA 2011 classification list. RESULTS: Four hundred and five of 2528 (16%) patients failed therapy containing atazanavir as a first PI over a median (IQR) follow-up of 1.76 (0.84-3.15) years and 322 resistance tests were available for analysis. Recognized major atazanavir mutations were found in six atazanavir-experienced patients (P < 0.001), including I50L and N88S. The minor mutations most strongly associated with atazanavir experience were M36I, M46I, F53L, A71V, V82T and I85V (P < 0.05). Multiple novel mutations, I15S, L19T, K43T, L63P/V, K70Q, V77I and L89I/T/V, were also associated with atazanavir experience. CONCLUSIONS: Viral failure on atazanavir-containing regimens was not common and major resistance mutations were rare, suggesting that adherence may be a major contributor to viral failure. Novel mutations were described that have not been previously documented.

CD38 in Advanced Prostate Cancers.

BACKGROUND: CD38, a druggable ectoenzyme, is involved in the generation of adenosine, which is implicated in tumour immune evasion. Its expression and role in prostate tumour-infiltrating immune cells (TIICs) have not been elucidated. OBJECTIVE: To characterise CD38 expression on prostate cancer (PC) epithelial cells and TIICs, and to associate this expression with clinical outcomes. DESIGN, SETTING, AND PARTICIPANTS: RNAseq from 159 patients with metastatic castration-resistant prostate cancer (mCRPC) in the International Stand Up To Cancer/Prostate Cancer Foundation (SU2C/PCF) cohort and 171 mCRPC samples taken from 63 patients in the Fred Hutchinson Cancer Research Centre cohort were analysed. CD38 expression was immunohistochemically scored by a validated assay on 51 castration-resistant PC (CRPC) and matching, same-patient castration-sensitive PC (CSPC) biopsies obtained between 2016 and 2018, and was associated with retrospectively collected clinical data. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: mCRPC transcriptomes were analysed for associations between CD38 expression and gene expression signatures. Multiplex immunofluorescence determined CD38 expression in PC biopsies. Differences in CD38+ TIIC densities between CSPC and CRPC biopsies were analysed using a negative binomial mixed model. Differences in the proportions of CD38+ epithelial cells between non-matched benign prostatic epithelium and PC were compared using Fisher's exact test. Differences in the proportions of biopsies containing CD38+ tumour epithelial cells between matched CSPC and CRPC biopsies were compared by McNemar's test. Univariable and multivariable survival analyses were performed using Cox regression models. RESULTS AND LIMITATIONS: CD38 mRNA expression in mCRPC was most significantly associated with upregulated immune signalling pathways. CD38 mRNA expression was associated with interleukin (IL)-12, IL-23, and IL-27 signalling signatures as well as immunosuppressive adenosine signalling and T cell exhaustion signatures. CD38 protein was frequently expressed on phenotypically diverse TIICs including B cells and myeloid cells, but largely absent from tumour epithelial cells. CD38+ TIIC density increased with progression to CRPC and was independently associated with worse overall survival. Future studies are required to dissect TIIC CD38 function. CONCLUSIONS: CD38+ prostate TIICs associate with worse survival and immunosuppressive mechanisms. The role of CD38 in PC progression warrants investigation as insights into its functions may provide rationale for CD38 targeting in lethal PC. PATIENT SUMMARY: CD38 is expressed on the surface of white blood cells surrounding PC cells. These cells may impact PC growth and treatment resistance. Patients with PC with more CD38-expressing white blood cells are more likely to die earlier.

HER3 Is an Actionable Target in Advanced Prostate Cancer.

It has been recognized for decades that ERBB signaling is important in prostate cancer, but targeting ERBB receptors as a therapeutic strategy for prostate cancer has been ineffective clinically. However, we show here that membranous HER3 protein is commonly highly expressed in lethal prostate cancer, associating with reduced time to castration resistance (CR) and survival. Multiplex immunofluorescence indicated that the HER3 ligand NRG1 is detectable primarily in tumor-infiltrating myelomonocytic cells in human prostate cancer; this observation was confirmed using single-cell RNA sequencing of human prostate cancer biopsies and murine transgenic prostate cancer models. In castration-resistant prostate cancer (CRPC) patient-derived xenograft organoids with high HER3 expression as well as mouse prostate cancer organoids, recombinant NRG1 enhanced proliferation and survival. Supernatant from murine bone marrow-derived macrophages and myeloid-derived suppressor cells promoted murine prostate cancer organoid growth in vitro, which could be reversed by a neutralizing anti-NRG1 antibody and ERBB inhibition. Targeting HER3, especially with the HER3-directed antibody-drug conjugate U3-1402, exhibited antitumor activity against HER3-expressing prostate cancer. Overall, these data indicate that HER3 is commonly overexpressed in lethal prostate cancer and can be activated by NRG1 secreted by myelomonocytic cells in the tumor microenvironment, supporting HER3-targeted therapeutic strategies for treating HER3-expressing advanced CRPC. SIGNIFICANCE: HER3 is an actionable target in prostate cancer, especially with anti-HER3 immunoconjugates, and targeting HER3 warrants clinical evaluation in prospective trials.

Early Post-treatment Prostate-specific Antigen at 4 Weeks and Abiraterone and Enzalutamide Treatment for Advanced Prostate Cancer: An International Collaborative Analysis.

BACKGROUND: Declines in prostate-specific antigen (PSA) levels at 12wk are used to evaluate treatment response in metastatic castration-resistant prostate cancer (mCRPC). PSA fall by ≥30% at 4wk (PSA4w30) has been reported to be associated with better outcome in a single-centre cohort study. OBJECTIVE: To evaluate clinical relevance of early PSA decline in mCRPC patients treated with next-generation hormonal treatments (NGHTs) such as abiraterone and enzalutamide. DESIGN, SETTING, AND PARTICIPANTS: This was a retrospective multicentre analysis. Eligible patients received NGHT for mCRPC between 6 January 2006 and 31 December 2017 in 13 cancer centres worldwide, and had PSA levels assessed at baseline and at 4 and/or 12wk after treatment. PSA response was defined as a ≥30% decline (progression as a ≥25% increase) from baseline. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Association with overall survival (OS) was analysed using landmark multivariable Cox regression adjusting for previous chemotherapy, including cancer centre as a shared frailty term. RESULTS AND LIMITATIONS: We identified 1358 mCRPC patients treated with first-line NGHT (1133 had PSA available at 4wk, and 948 at both 4 and 12wk). Overall, 583 (52%) had a PSA4w30; it was associated with longer OS (median: 23; 95% confidence interval [CI]: 21-25) compared with no change (median: 17; 95% CI: 15-18) and progression (median: 13; 95% CI: 10-15). A PSA12w30 was associated with lower mortality (median OS 22 vs 14; hazard ratio=0.57; 95% CI=0.48-0.67; p<0.001). PSA4w30 strongly correlated with PSA12w30 (ρ=0.91; 95% CI=0.90-0.92; p<0.001). In total, 432/494 (87%) with a PSA4w30 achieved a PSA12w30. Overall, 11/152 (7%) patients progressing at 4wk had a PSA12w30 (1% of the overall population). CONCLUSIONS: PSA changes in the first 4wk of NGHT therapies are strongly associated with clinical outcome from mCRPC and can help guide early treatment switch decisions. PATIENT SUMMARY: Prostate-specific antigen changes at 4wk after abiraterone/enzalutamide treatment are important to determine patients' outcome and should be taken into consideration in clinical practice.

Genomics of lethal prostate cancer at diagnosis and castration resistance.

The genomics of primary prostate cancer differ from those of metastatic castration-resistant prostate cancer (mCRPC). We studied genomic aberrations in primary prostate cancer biopsies from patients who developed mCRPC, also studying matching, same-patient, diagnostic, and mCRPC biopsies following treatment. We profiled 470 treatment-naive prostate cancer diagnostic biopsies and, for 61 cases, mCRPC biopsies, using targeted and low-pass whole-genome sequencing (n = 52). Descriptive statistics were used to summarize mutation and copy number profile. Prevalence was compared using Fisher's exact test. Survival correlations were studied using log-rank test. TP53 (27%) and PTEN (12%) and DDR gene defects (BRCA2 7%; CDK12 5%; ATM 4%) were commonly detected. TP53, BRCA2, and CDK12 mutations were markedly more common than described in the TCGA cohort. Patients with RB1 loss in the primary tumor had a worse prognosis. Among 61 men with matched hormone-naive and mCRPC biopsies, differences were identified in AR, TP53, RB1, and PI3K/AKT mutational status between same-patient samples. In conclusion, the genomics of diagnostic prostatic biopsies acquired from men who develop mCRPC differ from those of the nonlethal primary prostatic cancers. RB1/TP53/AR aberrations are enriched in later stages, but the prevalence of DDR defects in diagnostic samples is similar to mCRPC.

Prostate-specific Membrane Antigen Heterogeneity and DNA Repair Defects in Prostate Cancer.

BACKGROUND: Prostate-specific membrane antigen (PSMA; folate hydrolase) prostate cancer (PC) expression has theranostic utility. OBJECTIVE: To elucidate PC PSMA expression and associate this with defective DNA damage repair (DDR). DESIGN, SETTING, AND PARTICIPANTS: Membranous PSMA (mPSMA) expression was scored immunohistochemically from metastatic castration-resistant PC (mCRPC) and matching, same-patient, diagnostic biopsies, and correlated with next-generation sequencing (NGS) and clinical outcome data. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Expression of mPSMA was quantitated by modified H-score. Patient DNA was tested by NGS. Gene expression and activity scores were determined from mCRPC transcriptomes. Statistical correlations utilised Wilcoxon signed rank tests, survival was estimated by Kaplan-Meier test, and sample heterogeneity was quantified by Shannon's diversity index. RESULTS AND LIMITATIONS: Expression of mPSMA at diagnosis was associated with higher Gleason grade (p=0.04) and worse overall survival (p=0.006). Overall, mPSMA expression levels increased at mCRPC (median H-score [interquartile range]: castration-sensitive prostate cancer [CSPC] 17.5 [0.0-60.0] vs mCRPC 55.0 [2.8-117.5]). Surprisingly, 42% (n=16) of CSPC and 27% (n=16) of mCRPC tissues sampled had no detectable mPSMA (H-score <10). Marked intratumour heterogeneity of mPSMA expression, with foci containing no detectable PSMA, was observed in all mPSMA expressing CSPC (100%) and 37 (84%) mCRPC biopsies. Heterogeneous intrapatient mPSMA expression between metastases was also observed, with the lowest expression in liver metastases. Tumours with DDR had higher mPSMA expression (p=0.016; 87.5 [25.0-247.5] vs 20 [0.3-98.8]; difference in medians 60 [5.0-95.0]); validation cohort studies confirmed higher mPSMA expression in patients with deleterious aberrations in BRCA2 (p<0.001; median H-score: 300 [165-300]; difference in medians 195.0 [100.0-270.0]) and ATM (p=0.005; 212.5 [136.3-300]; difference in medians 140.0 [55.0-200]) than in molecularly unselected mCRPC biopsies (55.0 [2.75-117.5]). Validation studies using mCRPC transcriptomes corroborated these findings, also indicating that SOX2 high tumours have low PSMA expression. CONCLUSIONS: Membranous PSMA expression is upregulated in some but not all PCs, with mPSMA expression demonstrating marked inter- and intrapatient heterogeneity. DDR aberrations are associated with higher mPSMA expression and merit further evaluation as predictive biomarkers of response for PSMA-targeted therapies in larger, prospective cohorts. PATIENT SUMMARY: Through analysis of prostate cancer samples, we report that the presence of prostate-specific membrane antigen (PSMA) is extremely variable both within one patient and between different patients. This may limit the usefulness of PSMA scans and PSMA-targeted therapies. We show for the first time that prostate cancers with defective DNA repair produce more PSMA and so may respond better to PSMA-targeting treatments.

Androgen receptor splice variant-7 expression emerges with castration resistance in prostate cancer.

BACKGROUND: Liquid biopsies have demonstrated that the constitutively active androgen receptor splice variant-7 (AR-V7) associates with reduced response and overall survival from endocrine therapies in castration-resistant prostate cancer (CRPC). However, these studies provide little information pertaining to AR-V7 expression in prostate cancer (PC) tissue. METHODS: Following generation and validation of a potentially novel AR-V7 antibody for IHC, AR-V7 protein expression was determined for 358 primary prostate samples and 293 metastatic biopsies. Associations with disease progression, full-length androgen receptor (AR-FL) expression, response to therapy, and gene expression were determined. RESULTS: We demonstrated that AR-V7 protein is rarely expressed (<1%) in primary PC but is frequently detected (75% of cases) following androgen deprivation therapy, with further significant (P = 0.020) increase in expression following abiraterone acetate or enzalutamide therapy. In CRPC, AR-V7 expression is predominantly (94% of cases) nuclear and correlates with AR-FL expression (P ≤ 0.001) and AR copy number (P = 0.026). However, dissociation of expression was observed, suggesting that mRNA splicing remains crucial for AR-V7 generation. AR-V7 expression was heterogeneous between different metastases from a patient, although AR-V7 expression was similar within a metastasis. Moreover, AR-V7 expression correlated with a unique 59-gene signature in CRPC, including HOXB13, a critical coregulator of AR-V7 function. Finally, AR-V7-negative disease associated with better prostate-specific antigen (PSA) responses (100% vs. 54%, P = 0.03) and overall survival (74.3 vs. 25.2 months, hazard ratio 0.23 [0.07-0.79], P = 0.02) from endocrine therapies (pre-chemotherapy). CONCLUSION: This study provides impetus to develop therapies that abrogate AR-V7 signaling to improve our understanding of AR-V7 biology and to confirm the clinical significance of AR-V7. FUNDING: Work at the University of Washington and in the Plymate and Nelson laboratories is supported by the Department of Defense Prostate Cancer Research Program (W81XWH-14-2-0183, W81XWH-12-PCRP-TIA, W81XWH-15-1-0430, and W81XWH-13-2-0070), the Pacific Northwest Prostate Cancer SPORE (P50CA97186), the Institute for Prostate Cancer Research, the Veterans Affairs Research Program, the NIH/National Cancer Institute (P01CA163227), and the Prostate Cancer Foundation. Work in the de Bono laboratory was supported by funding from the Movember Foundation/Prostate Cancer UK (CEO13-2-002), the US Department of Defense (W81XWH-13-2-0093), the Prostate Cancer Foundation (20131017 and 20131017-1), Stand Up To Cancer (SU2C-AACR-DT0712), Cancer Research UK (CRM108X-A25144), and the UK Department of Health through an Experimental Cancer Medicine Centre grant (ECMC-CRM064X).

Clinical Utility of Circulating Tumour Cell Androgen Receptor Splice Variant-7 Status in Metastatic Castration-resistant Prostate Cancer.

BACKGROUND: Detection of androgen receptor splice variant-7 (AR-V7) mRNA in circulating tumour cells (CTCs) is associated with worse outcome in metastatic castration-resistant prostate cancer (mCRPC). However, studies rarely report comparisons with CTC counts and biopsy AR-V7 protein expression. OBJECTIVE: To determine the reproducibility of AdnaTest CTC AR-V7 testing, and associations with clinical characteristics, CellSearch CTC counts, tumour biopsy AR-V7 protein expression and overall survival (OS). DESIGN, SETTING, AND PARTICIPANTS: CTC AR-V7 status was determined for 227 peripheral blood samples, from 181 mCRPC patients with CTC counts (202 samples; 136 patients) and matched mCRPC biopsies (65 samples; 58 patients). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: CTC AR-V7 status was associated with clinical characteristics, CTC counts, and tissue biopsy AR-V7 protein expression. The association of CTC AR-V7 status and other baseline variables with OS was determined. RESULTS AND LIMITATIONS: Of the samples, 35% were CTC+/AR-V7+. CTC+/AR-V7+ samples had higher CellSearch CTC counts (median CTC; interquartile range [IQR]: 60, 19-184 vs 9, 2-64; Mann-Whitney test p<0.001) and biopsy AR-V7 protein expression (median H-score, IQR: 100, 63-148 vs 15, 0-113; Mann-Whitney test p=0.004) than CTC+/AR-V7- samples. However, both CTC- (63%) and CTC+/AR-V7- (62%) patients had detectable AR-V7 protein in contemporaneous biopsies. After accounting for baseline characteristics, there was shorter OS in CTC+/AR-V7+ patients than in CTC- patients (hazard ratio [HR] 2.13; 95% confidence interval [CI] 1.23-3.71; p=0.02); surprisingly, there was no evidence that CTC+/AR-V7+ patients had worse OS than CTC+/AR-V7- patients (HR 1.26; 95% CI 0.73-2.17; p=0.4). A limitation of this study was the heterogeneity of treatment received. CONCLUSIONS: Studies reporting the prognostic relevance of CTC AR-V7 status must account for CTC counts. Discordant CTC AR-V7 results and AR-V7 protein expression in matched, same-patient biopsies are reported. PATIENT SUMMARY: Liquid biopsies that determine circulating tumour cell androgen receptor splice variant-7 status have the potential to impact treatment decisions in metastatic castration-resistant prostate cancer patients. Robust clinical qualification of these assays is required before their routine use.

Randomized Phase II Study Evaluating Palbociclib in Addition to Letrozole as Neoadjuvant Therapy in Estrogen Receptor-Positive Early Breast Cancer: PALLET Trial.

PURPOSE: CDK4/6 inhibitors are used to treat estrogen receptor (ER)-positive metastatic breast cancer (BC) in combination with endocrine therapy. PALLET is a phase II randomized trial that evaluated the effects of combination palbociclib plus letrozole as neoadjuvant therapy. PATIENTS AND METHODS: Postmenopausal women with ER-positive primary BC and tumors greater than or equal to 2.0 cm were randomly assigned 3:2:2:2 to letrozole (2.5 mg/d) for 14 weeks (A); letrozole for 2 weeks, then palbociclib plus letrozole to 14 weeks (B); palbociclib for 2 weeks, then palbociclib plus letrozole to 14 weeks (C); or palbociclib plus letrozole for 14 weeks. Palbociclib 125 mg/d was administered orally on a 21-days-on, 7-days-off schedule. Core-cut biopsies were taken at baseline and 2 and 14 weeks. Coprimary end points for letrozole versus palbociclib plus letrozole groups (A v B + C + D) were change in Ki-67 (protein encoded by the  MKI67 gene; immunohistochemistry) between baseline and 14 weeks and clinical response (ordinal and ultrasound) after 14 weeks. Complete cell-cycle arrest was defined as Ki-67 less than or equal to 2.7%. Apoptosis was characterized by cleaved poly (ADP-ribose) polymerase. RESULTS: Three hundred seven patients were recruited. Clinical response was not significantly different between palbociclib plus letrozole and letrozole groups ( P = .20; complete response + partial response, 54.3% v 49.5%), and progressive disease was 3.2% versus 5.4%, respectively. Median log-fold change in Ki-67 was greater with palbociclib plus letrozole compared with letrozole (-4.1 v -2.2; P < .001) in the 190 evaluable patients (61.9%), corresponding to a geometric mean change of -97.4% versus -88.5%. More patients on palbociclib plus letrozole achieved complete cell-cycle arrest (90% v 59%; P < .001). Median log-fold change (suppression) of cleaved poly (ADP-ribose) polymerase was greater with palbociclib plus letrozole versus letrozole (-0.80 v -0.42; P < .001). More patients had grade 3 or greater toxicity on palbociclib plus letrozole (49.8% v 17.0%; P < .001) mainly because of asymptomatic neutropenia. CONCLUSION: Adding palbociclib to letrozole significantly enhanced the suppression of malignant cell proliferation (Ki-67) in primary ER-positive BC, but did not increase the clinical response rate over 14 weeks, which was possibly related to a concurrent reduction in apoptosis.

A study of 1088 consecutive cases of electrolyte abnormalities in oncology phase I trials.

BACKGROUND: The incidence and clinical significance of electrolyte abnormalities (EAs) in phase I clinical trials are unknown. The objective of this study is to evaluate the incidence and severity of EAs, graded according to CTCAE, v4.03, to identify variables associated with EAs and their prognostic significance in a phase I population. METHODS: A retrospective chart review was performed of 1088 cases in 82 phase I clinical trials consecutively treated from 2011 to 2015 at the Drug Development Unit of the Royal Marsden Hospital. Cox regression analysis was performed to examine the relationship between overall survival (OS) and baseline characteristics, treating the occurrence of grade III/IV EAs as a time-varying covariate. RESULTS: The most common emergent EAs (all grades) were as follows: hyponatraemia 62%, hypokalaemia 40%, hypophosphataemia 32%, hypomagnesaemia 17% and hypocalcaemia 12%. Grade III/IV EAs occurred in 19% of cases. Grade III/IV EAs occurred during the dose-limiting toxicity window in 8.46% of cases. Diarrhoea was associated with hypomagnesaemia at all grades (p < 0.001), hyponatraemia at all grades (p = 0.006) and with G3/G4 hypokalaemia (p = 0.02). Baseline hypoalbuminaemia and hyponatraemia were associated with a higher risk of developing other EAs during the trial in the univariate analysis. Patients who developed grade III/IV EAs during follow-up had an inferior median OS (26 weeks vs 37 weeks, hazard ratio = 1.61; p < 0.001). CONCLUSION: This is the first study to demonstrate the clinical significance of baseline hypoalbuminaemia and hyponatraemia, which are predictors of development of other EAs in phase I patients. Grade III/IV EAs are adverse prognostic factors of OS independent of serum albumin levels.

Neutrophil-lymphocyte ratio kinetics in patients with advanced solid tumours on phase I trials of PD-1/PD-L1 inhibitors.

BACKGROUND: Although the neutrophil-lymphocyte ratio (NLR) is prognostic in many oncological settings, its significance in the immunotherapy era is unknown. Mechanistically, PD-1/PD-L1 inhibitors may alter NLR. We sought to characterise NLR kinetics in patients with advanced solid tumours treated with PD-1/PD-L1 inhibitors. METHODS: Electronic records of patients treated with PD-1/PD-L1 inhibitors on phase I trials across three sites were reviewed. A high NLR (hNLR) was predefined as >5. Univariate logistic regression models were used for toxicity, response analyses and Cox models for overall survival (OS) and progression-free survival analyses. Landmark analyses were performed (cycle two, three). Longitudinal analysis of NLR was performed utilising a mixed effect regression model. RESULTS: The median OS for patients with hNLR was 8.5 months and 19.4 for patients with low NLR, (hazard ratio [HR] = 1.85, 95% confidence interval [CI] 1.15-2.96, p = 0.01). On landmark analysis, hNLR was significantly associated with inferior OS at all time points with a similar magnitude of effect over time (p < 0.05). On multivariate analysis, NLR was associated with OS (HR 1.06, 95% CI 1.01-1.11, p = 0.01). NLR did not correlate with increased immune toxicity. Longitudinally, NLR correlated with response: NLR decreased by 0.09 (95% CI: -0.15 to -0.02; p = 0.01) per month in responders compared with non-responders. CONCLUSIONS: hNLR at baseline and during treatment is adversely prognostic in patients with advanced malignancies receiving PD-1/PD-L1 blockade. Importantly, NLR reduced over time in responders to immunotherapy. Taken together, these data suggest that baseline and longitudinal NLR may have utility as a unique biomarker to aid clinical decision-making in patients receiving immunotherapy.