Ribonucleotide reductase small subunit M2 is a master driver of aggressive prostate cancer

Although there are molecularly distinct subtypes of prostate cancer, no molecular classification system is used clinically. The ribonucleotide reductase small subunit M2 (RRM2) gene plays an oncogenic role in many cancers. Our previous study elucidated comprehensive molecular mechanisms of RRM2 in prostate cancer (PC). Given the potent functions of RRM2, we set out to determine whether the RRM2 signature can be used to identify aggressive subtypes of PC. We applied gene ontology and pathway analysis in RNA‐seq datasets from PC cells overexpressing RRM2. We refined the RRM2 signature by integrating it with two molecular classification systems (PCS and PAM50 subtypes) that define aggressive PC subtypes (PCS1 and luminal B) and correlated signatures with clinical outcomes in six published cohorts comprising 4000 cases of PC. Increased expression of genes in the RRM2 signature was significantly correlated with recurrence, high Gleason score, and lethality of PC. Patients with high RRM2 levels showed higher PCS1 score, suggesting the aggressive PC feature. Consistently, RRM2‐regulated genes were highly enriched in the PCS1 signature from multiple PC cohorts. A simplified RRM2 signature (12 genes) was identified by intersecting the RRM2 signature, PCS1 signature, and the PAM50 classifier. Intriguingly, inhibition of RRM2 specifically targets PCS1 and luminal B genes. Furthermore, 11 genes in the RRM2 signature were correlated with enzalutamide resistance by using a single‐cell RNA‐seq dataset from PC circulating tumor cells. Finally, high expression of RRM2 was associated with an immunosuppressive tumor‐immune microenvironment in both primary prostate cancer and metastatic prostate cancer using CIBERSORT analysis and LM22, a validated leukocyte gene signature matrix. These data demonstrate that RRM2 is a driver of aggressive prostate cancer subtypes and contributes to immune escape, suggesting that RRM2 inhibition may be of clinical benefit for patients with PC.

Patient and Public Involvement (PPI) in evidence synthesis: how the PatMed study approached embedding audience responses into the expression of a meta-ethnography

Background

Patient and public involvement (PPI) has become enshrined as an important pillar of health services empirical research, including PPI roles during stages of research development and analysis and co-design approaches. Whilst user participation has been central to qualitative evidence synthesis (QES) for decades, as seen in the Cochrane consumer network and guidelines, meta-ethnography has been slow to incorporate user participation and published examples of this occurring within meta-ethnography are sparse.

In this paper, drawing upon our own experience of conducting a meta-ethnography, we focus on what it means in practice to ‘express a synthesis’ (stage 7). We suggest the methodological importance of ‘expression’ in Noblit and Hare’s seven stage process (Noblit, GW and Hare, RD. Meta-ethnography: synthesizing qualitative studies, 1988) has been overlooked, and in particular, opportunities for PPI user participation within it.

Methods

Meta-ethnography comprises a seven-stage process of evidence synthesis. Noblit and Hare describe the final 7th stage of the meta-ethnography process as ‘expression of synthesis’, emphasizing co-construction of findings with the audience. In a previous study we conducted a meta-ethnography exploring patient and student experience of medical education within primary care contexts. We subsequently presented and discussed initial meta-ethnography findings with PPI (students and patients) in focus groups and interviews. We transcribed patient and student PPI interpretations of synthesis findings. As a research team, we then translated these into our existing meta-ethnography findings.

Results

We describe, with examples, the process of involving PPI in stage 7 of meta-ethnography and discuss three methodological implications of incorporating PPI within an interpretative approach to QES: (1) we reflect on the construct hierarchy of user participants’ interpretations and consider whether incorporating these additional 1st order, 2nd level constructs implies an additional logic of 3rd order 2nd level constructs of the QES team; (2) we discuss the link between PPI user participation and what Noblit and Hare may have meant by ideas of ‘expression’ and ‘audience’ as integral to stage 7; and (3) we link PPI user participation to Noblit and Hare’s underlying theory of social explanation, i.e. how expression of the synthesis is underpinned by ideas of translation and that the synthesis must be ‘translated in the audience’s (user participants) particular language’.

Conclusions

The paper aims to complement recent attempts in the literature to refine and improve guidance on conducting a meta-ethnography, highlighting opportunities for PPI user participation in the processes of interpretation, translation and expression. We discuss the implications of user participation in meta-ethnography on ideas of ‘generalisability’.

Impact of new definitions of pre-eclampsia on incidence and performance of first-trimester screening

OBJECTIVE

The traditional definition of pre-eclampsia (PE) is based on the development of hypertension and proteinuria. This has been revised recently to include cases without proteinuria but with evidence of renal, hepatic or hematological dysfunction. The aim of this study was to examine the impact of new definitions of PE on, first, the incidence and severity of the disease and, second, the performance of the competing-risks model for first-trimester assessment of risk for PE.

METHODS

This was a retrospective study of 66 964 singleton pregnancies that were classified as having PE, gestational hypertension (GH) or no PE or GH, according to the traditional criteria of the International Society for the Study of Hypertension in Pregnancy (ISSHP-old), which defines PE as the presence of both hypertension and proteinuria. We reviewed the records of pregnancies with GH, and those cases with high creatinine or liver enzymes or low platelet count were reclassified as having PE, according to the new criteria of ISSHP (ISSHP-new) and the new criteria of the American College of Obstetricians and Gynecologists (ACOG). The groups of PE according to the traditional and new criteria were compared for, first, gestational age at delivery, birth-weight percentile and incidence of a small-for-gestational-age (SGA) neonate with birth weight < 10^th percentile and perinatal death, and, second, the predictive performance for preterm PE of the competing-risks model based on the combination of maternal risk factors, uterine artery pulsatility index, mean arterial pressure and serum placental growth factor at 11-13 weeks' gestation (triple test).

RESULTS

According to ISSHP-old, 1870 (2.8%) cases had PE, 2182 (3.3%) had GH and 62 912 (94.0%) had no PE or GH. The incidence of PE according to ACOG was 3.0% (2029/66 964) and ISSHP-new was 3.4% (2301/66 964). Median gestational age at delivery in the extra cases of PE according to ACOG (difference, 1.3 weeks; 95% CI, 0.71-1.71 weeks) and in the extra cases of PE according to ISSHP-new (difference, 1.5 weeks; 95% CI, 1.29-1.71 weeks) was higher than in cases with PE according to ISSHP-old (38.4 weeks). The incidence of a SGA neonate in the extra cases of PE according to ACOG (relative risk, 0.57; 95% CI, 0.42-0.79) and in the extra cases of PE according to ISSHP-new (relative risk, 0.52; 95% CI, 0.42-0.65) was lower than in the cases of PE according to ISSHP-old (33.64%). In first-trimester screening for preterm PE by the triple test, the detection rate, at a 10% false-positive rate, was 75.9% (95% CI, 70.8-80.6%) for ISSHP-old, 74.3% (95% CI, 69.2-79.0%) for ACOG and 74.0% (95% CI, 68.9-78.6%) for ISSHP-new.

CONCLUSIONS

The new definitions of PE resulted in, first, an increase in pregnancies classified as having PE but the additional cases had milder disease, and, second, a non-significant decrease in the performance of first-trimester screening for PE. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Development of novel MnO2 coated carbon felt cathode for microbial electroreduction of CO2 to biofuels

Fabrication of superior and cost-effective cathodic materials is vital in manufacturing sustainable microbial electrolysis cells (MECs) for biofuels production. In the present study, a novel manganese dioxide (MnO₂) coated felt cathode (Mn/CF) has been developed for MECs using electrodeposition method via potentiostat. MnO₂ is considered to encourage exogenous electron exchange and, in this way, improves the reduction of carbon dioxide (CO₂). MnO₂, as a cathodic catalyst, enhances the rate of biofuel production, electron transfer, and significantly reduces the cost of MECs. A maximum stabilized current density of 3.70 ± 0.5 mA/m² was obtained in case of MnO₂-coated Mn/CF based MEC, which was more than double the non-coated carbon felt (CF) cathode (1.70 ± 0.5 mA/m²). The dual chamber Mn/CF-MEC achieved the highest production rate of acetic acid (37.9 mmol/L) that was significantly higher (43.0%) in comparison to the non-coated CF-MEC. The cyclic voltammograms further verified the substantial enhancement in the electron transfer between the MnO₂ coated cathode and microbes. The obtained results demonstrate that MnO₂ interacted electrochemically with microbial cells and enhanced the extracellular electron transfer, therefore validating its potential role in biofuel production. The MnO₂ coated CF further offered higher electrode surface area and better electron transfer efficiency, suggesting its applicability in the large-scale MECs.

Suppresive plants as weed management tool: Managing Parthenium hysterophorus under simulated grazing in Australian grasslands

Parthenium hysterophorus L. is among one of the most problematic invasive grassland weeds in Australia, and in many other countries around the world. It can reduce pasture and livestock production, natural community biodiversity, and negatively affect human and animal health. Sowing of selected suppressive pasture plants in parthenium weed infested grasslands has shown potential to improve efficacy of management. However, such species need to be tested for their ability to suppress weed growth under grazing conditions. The parthenium weed suppressive and fodder production capacity of six selected pasture species [purple pigeon grass (Setaria incrassata), buffel grass (Cenchrus ciliaris), butterfly pea (Clitoria ternatea), Kangaroo grass (Themeda triandra), bull Mitchell grass (Astrebla squarrosa) and Indian bluegrass (Bothriochloa pertusa)] was tested under no (0%), low (25%), moderate (50%) and heavy (75%) simulated grazing pressures in a grassland area of south-central Queensland, Australia. Purple pigeon grass, buffel grass and butterfly pea legume suppressed the growth of parthenium weed by >50% under low and moderate simulated grazing pressures, as well as generating moderate to high amounts of fodder biomass (up to 5.07 t ha^-1 per year). Native species, Kangaroo grass and bull Mitchell grass both suppressed the parthenium weed's growth by >50% under low simulated grazing pressure, however, they generated low to moderate amounts of biomass, 1.83 t ha^-1 and 2.7 t ha^-1 per year, respectively. The sowing of selected suppressive pasture species in parthenium weed infested grasslands with low-to-moderate grazing pressure, assuming this corresponds closely with the simulated treatment, would provide an additional tool to the best practice weed management strategy as well as sustaining fodder production.

Prediction of large-for-gestational-age neonate by routine third-trimester ultrasound

OBJECTIVES

First, to evaluate and compare the performance of routine ultrasonographic estimated fetal weight (EFW) and fetal abdominal circumference (AC) at 31 + 0 to 33 + 6 and 35 + 0 to 36 + 6 weeks' gestation in the prediction of a large-for-gestational-age (LGA) neonate born at ≥ 37 weeks' gestation. Second, to assess the additive value of fetal growth velocity between 32 and 36 weeks' gestation to the performance of EFW at 35 + 0 to 36 + 6 weeks' gestation for prediction of a LGA neonate. Third, to define the predictive performance for a LGA neonate of different EFW cut-offs on routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. Fourth, to propose a two-stage strategy for identifying pregnancies with a LGA fetus that may benefit from iatrogenic delivery during the 38^th gestational week.

METHODS

This was a retrospective study. First, data from 21 989 singleton pregnancies that had undergone routine ultrasound examination at 31 + 0 to 33 + 6 weeks' gestation and 45 847 that had undergone routine ultrasound examination at 35 + 0 to 36 + 6 weeks were used to compare the predictive performance of EFW and AC for a LGA neonate with birth weight > 90^th and > 97^th percentiles born at ≥ 37 weeks' gestation. Second, data from 14 497 singleton pregnancies that had undergone routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation and had a previous scan at 30 + 0 to 34 + 6 weeks were used to determine, through multivariable logistic regression analysis, whether addition of growth velocity, defined as the difference in EFW Z-score or AC Z-score between the early and late third-trimester scans divided by the time interval between the scans, improved the performance of EFW at 35 + 0 to 36 + 6 weeks in the prediction of delivery of a LGA neonate at ≥ 37 weeks' gestation. Third, in the database of the 45 847 pregnancies that had undergone routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation, the screen-positive and detection rates for a LGA neonate born at ≥ 37 weeks' gestation and ≤ 10 days after the initial scan were calculated for different EFW percentile cut-offs between the 50^th and 90^th percentiles.

RESULTS

First, the areas under the receiver-operating characteristics curves (AUC) of screening for a LGA neonate were significantly higher using EFW Z-score than AC Z-score and at 35 + 0 to 36 + 6 than at 31 + 0 to 33 + 6 weeks' gestation (P < 0.001 for all). Second, the performance of screening for a LGA neonate achieved by EFW Z-score at 35 + 0 to 36 + 6 weeks was not significantly improved by addition of EFW growth velocity or AC growth velocity. Third, in screening by EFW > 90^th percentile at 35 + 0 to 36 + 6 weeks' gestation, the predictive performance for a LGA neonate born at ≥ 37 weeks' gestation was modest (65% and 46% for neonates with birth weight > 97^th and > 90^th percentiles, respectively, at a screen-positive rate of 10%), but the performance was better for prediction of a LGA neonate born ≤ 10 days after the scan (84% and 71% for neonates with birth weight > 97^th and > 90^th percentiles, respectively, at a screen-positive rate of 11%). Fourth, screening by EFW > 70^th percentile at 35 + 0 to 36 + 6 weeks' gestation predicted 91% and 82% of LGA neonates with birth weight > 97^th and > 90^th percentiles, respectively, born at ≥ 37 weeks' gestation, at a screen-positive rate of 32%, and the respective values of screening by EFW > 85^th percentile for prediction of a LGA neonate born ≤ 10 days after the scan were 88%, 81% and 15%. On the basis of these results, it was proposed that routine fetal biometry at 36 weeks' gestation is a screening rather than diagnostic test for fetal macrosomia and that EFW > 70^th percentile should be used to identify pregnancies in need of another scan at 38 weeks, at which those with EFW > 85^th percentile should be considered for iatrogenic delivery during the 38^th  week.

CONCLUSIONS

First, the predictive performance for a LGA neonate by routine ultrasonographic examination during the third trimester is higher if the scan is carried out at 36 than at 32 weeks, the method of screening is EFW than fetal AC, the outcome measure is birth weight > 97^th than > 90^th percentile and if delivery occurs within 10 days than at any stage after assessment. Second, prediction of a LGA neonate by EFW > 90^th percentile is modest and this study presents a two-stage strategy for maximizing the prenatal prediction of a LGA neonate. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Maternal and neonatal complications of fetal macrosomia: cohort study

OBJECTIVE

To estimate the risks of maternal and neonatal complications in pregnancies with macrosomia.

METHODS

This was a retrospective cohort study conducted at a large maternity unit in the UK between January 2009 and December 2016. The incidence of maternal and neonatal complications in pregnancies with macrosomia, defined as birth weight (BW) > 4000 g, and in those with severe macrosomia, defined as BW > 4500 g, was compared with that in pregnancies with normal BW (2500-4000 g). Regression analysis was performed to determine odds ratios (ORs) for complications in macrosomic pregnancies compared to those with normal BW.

RESULTS

The study population of 35 548 pregnancies included 4522 (12.7%) with macrosomia, of which 643 (1.8%) had severe macrosomia, and 31 026 (87.3%) with normal BW. In the macrosomia group, the adjusted OR was 3.1 (95% CI, 2.6-3.6) for Cesarean section for failure to progress, 2.4 (95% CI, 2.0-3.0) for severe postpartum hemorrhage, 2.3 (95% CI, 1.9-2.8) for obstetric anal sphincter injury, 10.4 (95% CI, 8.6-12.6) for shoulder dystocia, 28.5 (95% CI, 8.9-90.7) for obstetric brachial plexus injury, 32.3 (95% CI, 3.8-278.2) for birth fractures and 4.4 (95% CI, 2.2-8.8) for hypoxic-ischemic encephalopathy. The respective values in pregnancies with severe macrosomia were 4.3 (95% CI, 3.1-6.1), 2.9 (95% CI, 1.9-4.4), 3.1 (95% CI, 1.9-5.1), 28.7 (95% CI, 20.8-39.8), 73.9 (95% CI, 15.1-363.2), 87.2 (95% CI, 7.7-985.0) and 13.8 (95% CI, 5.2-36.8).

CONCLUSION

Macrosomia is associated with serious adverse perinatal outcomes. This study provides accurate estimates of risks to aid in pregnancy management. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Maternal and neonatal complications of fetal macrosomia: systematic review and meta-analysis

OBJECTIVE

To determine accurate estimates of risks of maternal and neonatal complications in pregnancies with fetal macrosomia by performing a systematic review of the literature and meta-analysis.

METHODS

A search of MEDLINE, EMBASE, CINAHL and The Cochrane Library was performed to identify relevant studies reporting on maternal and/or neonatal complications in pregnancies with macrosomia having a birth weight (BW) > 4000 g and/or those with birth weight > 4500 g. Prospective and retrospective cohort and population-based studies that provided data regarding both cases and controls were included. Maternal outcomes assessed were emergency Cesarean section (CS), postpartum hemorrhage (PPH) and obstetric anal sphincter injury (OASIS). Neonatal outcomes assessed were shoulder dystocia, obstetric brachial plexus injury (OBPI) and birth fractures. Meta-analysis using a random-effects model was used to estimate weighted pooled estimates of summary statistics (odds ratio (OR) and 95% CI) for each complication, according to birth weight. Heterogeneity between studies was estimated using Cochran's Q, I2 statistic and funnel plots.

RESULTS

Seventeen studies reporting data on maternal and/or neonatal complications in pregnancy with macrosomia were included. In pregnancies with macrosomia having a BW > 4000 g, there was an increased risk of the maternal complications: emergency CS, PPH and OASIS, which had OR (95% CI) of 1.98 (1.80-2.18), 2.05 (1.90-2.22) and 1.91 (1.56-2.33), respectively. The corresponding values for pregnancies with BW > 4500 g were: 2.55 (2.33-2.78), 3.15 (2.14-4.63) and 2.56 (1.97-3.32). Similarly, in pregnancies with a BW > 4000 g, there was an increased risk of the neonatal complications: shoulder dystocia, OBPI and birth fractures, which had OR (95% CI) of 9.54 (6.76-13.46), 11.03 (7.06-17.23) and 6.43 (3.67-11.28), respectively. The corresponding values for pregnancies with a BW > 4500 g were: 15.64 (11.31-21.64), 19.87 (12.19-32.40) and 8.16 (2.75-24.23).

CONCLUSION

Macrosomia is associated with serious maternal and neonatal adverse outcomes. This study provides accurate estimates of these risks, which can be used for decisions on pregnancy management. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Abstract 283: Combination treatment of PARP and SRC inhibitors in BRCA2 mutated prostate cancer

Background: Recently, poly (adenosine diphosphate [ADP]-ribose) polymerase inhibitors (PARPi) have shown promise in metastatic castration resistant prostate cancers (mCRPC) patients harboring DNA repair defects due to mutations of BRCA1/2 and ATM. Despite responses, resistance is common and treatment modalities for PARPi-resistant patients are limited. We hypothesized that combining PARPi with other agents in BRCA2 altered tumors would create synergy and greater response rate and durability.

Methods: We established a transcriptomic profile associated with genomic deletion of BRCA2 (homozygous and heterozygous) using publicly available datasets from mCRPC patient tumors. To identify the significantly unregulated oncogenic signaling pathways associated with BRCA2 loss, we used gene-set enrichment analysis (GSEA). We also analyzed this transcriptomic profile by Toppgene suite to identify potential drug targets for BRCA2 deleted tumors. We used experimental human prostate cancer cell lines to validate our current observations from human clinical datasets and pathway analysis.

Results: Our GSEA analysis showed significant enrichment of the SRC signaling pathway in BRCA2-altered tumors, and based on the Toppgene suite, we also identified dasatinib (pharmacological inhibitor of SRC) as a potential agent for BRCA2-deleted tumors. Similarly, we observed significant up regulation of SRC phosphorylation in human prostate cancer cells (LNCaP-abl and PC3M) that harbor genomic deletion of BRCA2. We performed cell growth assays in these BRCA2 deleted cells treated with PARPi (olaparib, talazoparib), and dasatinib alone or in combination and calculated drug synergy based on the Chou-Talay Method. PC3M and LNCaP-abl prostate cancer cell lines showed different sensitivities to olaparib and talazoparib. We used olaparib for PC3M and talazoparib for LNCaP-abl cells. Co-administration of the PARPi and SRCi showed significant synergy in both cell lines compared to either inhibitors alone. We will develop the rationale for combining PARPi and SRCi in CRPC patients who harbor defects of BRCA2 after completion of our study in xenograft models.

Conclusion: Our study reveals the synergistic effect of PARPi and SRCi in prostate cancer cell lines. We believe this shows great potential for future clinical trials in patients with mCRPC harboring BRCA2 deletions.

Citation Format: Nabeela Khan, Goutam Chakraborty, Subhiksha Nandakumar, Ying Z. Mazzu, Mohammad Atiq, Yuki Yoshikawa, Gwo-Shu Mary Lee, Philip Kantoff. Combination treatment of PARP and SRC inhibitors in BRCA2 mutated prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 283.

Abstract 2534: A comparative analysis of fraction genome altered vs tumor mutational count in prostate cancer

Prostate cancer is the second leading cause of cancer related death among men in the United States. Although 5 new life-prolonging agents have been FDA-approved for castration resistant prostate cancer in the past 8 years, drug resistance limits the durability of responses to these agents for most patients. We hypothesized that biomarkers of genomic alterations, defined as fraction genome altered (% of copy number altered chromosome regions out of measured regions) and mutational count (number of mutational events per cases), were prognostic biomarkers which might provide insights into resistance mechanisms. We used The Cancer Genome Atlas (TCGA; n= 490 primary prostate cancer) dataset to analyze fraction of genome altered and tumor mutational count in prostate tumors. Patients whose primary prostate cancer harbored a high frequency of fraction genome altered exhibited significant disease progression in TCGA cohort . In contrast, we did not observe a significant association between high tumor mutational count and disease progression. Fraction genome altered was more significantly associated with Gleason grade compare to tumor mutation count. Interestingly, our preliminary observation showed that primary prostate cancer patients who harbor high fraction genome altered (&gt;6%), but low tumor mutational count (&lt;30/cases) exhibited shorter disease-free survival, indicating that those primary prostate cancer patients who harbor high fraction genome altered but low mutational count may have more aggressive prostate cancer. We have also developed a transcriptional signature which is associated with high fraction genome altered. . A detailed understanding of these molecular features will help us to design appropriate therapeutic approaches for different subsets of the disease. We hypothesize that cases with a high fraction of genome altered are associated with aggressive disease and those with lower mutational count may be associated with a diminished immunoresponsiveness.

Tumor mutational count and fraction genome alteration in various stages TCGA prostate cancerDisease Status (Gleason unadjusted)p valueGleasonp value (trend)Disease FreeRecurred/ Progressed6 (n=45)7 (n=244)&gt;=8 (n=198)Fraction Genome Altered (Mean + SEM)0.08248 ± 0.00490.1254 ± 0.01120.00030.02504 ±0.00370.05985 ± 0.00390.1425 ± 0.0087&lt; 2.2e-16Mutational Count (Mean + SEM)35.05 ± 1.35439.88 ± 2.6550.394429.42 ± 1.749,34.69 ± 0.9089,38.58 ± 1.272,=9.971e-05 (7 vs &gt;=8; p value 0.0445)

Citation Format: Goutam Chakraborty, Mohammad Atiq, Subhiksha Nandakumar, Ying Z. Mazzu, Joshua Armenia, Yuki Yoshikawa, Nabeela Khan, Gwo-Shu M. Lee, Lorelei Mucci, Philip W. Kantoff. A comparative analysis of fraction genome altered vs tumor mutational count in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2534.

Abstract 339: Mechanisms of resistance to poly (ADP-ribose) polymerase inhibitors in prostate cancer

Background: Poly (ADP-ribose) polymerase inhibitors (PARPi) have demonstrated promise in treating cancers with DNA damage repair (DDR) gene abnormalities. As a result, olaparib and more recently, rucaparib have been given Breakthrough Therapy designation by the FDA for use in metastatic castration resistant prostate cancer (mCRPC) with BRCA1/2 and ATM mutations. One of the problems encountered with PARPi is drug resistance which generally limits drug efficacy. Mechanistic studies on PARPi resistance have shown one of the main mechanisms of acquired resistance to be a reversion mutation of BRCA1/2. However, this is likely more applicable to cancers in which impaired BRCA1/2 function is due to a mutation rather than in prostate cancer (PC) where BRCA2 tends to be frequently deleted. Therefore, we hypothesize that mechanisms of resistance to PARPi in PC may involve alternative molecular mechanisms rather than a reversion mutation.

Methods: We used human castration-resistant PC cell lines that harbor genomic deletions of BRCA2, PC-3 and LnCaP-Abl, and performed cell viability (MTT) assays to determine the inhibitory growth (IG) concentrations of these cell lines with talazoparib and olaparib. We cultured parental PC-3 cells in sublethal concentrations (IG 50% and IG 90%) of talazoparib-supplemented media to develop talazoparib-resistant cells. RNA sequencing followed by gene-set enrichment analysis (GSEA) of hallmark gene sets was performed on the talazoparib-resistant PC-3 cells to understand the underlying molecular mechanisms.

Results: We observed that the talazoparib-resistant PC-3 cells exhibited significantly enhanced cell growth compared to parental cells when cultured in the IG 90% concentration of olaparib. However, interestingly, the talazoparib-resistant cells grew much slower in 2D compared to parental PC-3 cells when cultured in the PARPi-free media. Our transcriptomic analysis showed significant enrichment of various inflammatory response pathways, including TNF-α and IFNα/γ signaling pathways, in the talazoparib-resistant cells and even in the parental PC-3 cells transiently treated with talazoparib.

Conclusion: We hypothesize that resistance to PARPi in PC may be related to upregulation of inflammatory signaling. Therefore, further exploration of TNF-α and IFNα/γ and their role in PARPi resistance mechanisms may lead to the identification of targets that allow for overcoming PARPi resistance in PC.

Citation Format: Mohammad Atiq, Goutam Chakraborty, Subhiksha Nandakumar, Ying Z. Mazzu, Konrad Stopsack, Yuki Yoshikawa, Nabeela Khan, Gwo-Shu Mary Lee, Philip W. Kantoff. Mechanisms of resistance to poly (ADP-ribose) polymerase inhibitors in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 339.

High Transverse Scrotal Incision Orchiopexy for Undescended Testes

Bianchi squire first described scrotal incision orchiopexy as an alternative to the traditional approach in the1980s. In maximum premature and some mature infants, palpable testis is a common surgical problem. There are several surgical technique applied to overcome this surgical problems like combined inguinal and scrotal incision or single high transverse scrotal incision. The goal of this study assessed single high transverse scrotal incision for the management of PUT as regards to evaluate operative time, postoperative success and final cosmetic results. One hundred twenty patients were managed at the Paediatric Surgery Department of Mymensingh Medical College Hospital, Mymensingh, Bangladesh with PUT during the period from 2015 to March 2018. We operated all cases between 6 to 12 months and excluded more than 12 months of age and recurrent cases. This technique involves manipulation of the testis down to the scrotum so that it is secured between the thumb and index finger as a fixation is performed. After fixation of testis high transverse scrotal incision was given, all layers were separated. Then enter into inguinal cannel by cutting of external ring. After dissecting the testis come down through the incision. After making dartos pouch through the same incision and orchidopexy done. All infants were followed-up at 1 month, 2 months and 6 months to detect operative times as well as position, testicular atrophy and the final cosmetic appearance. Patient age ranged from 6 months to 12 months. A total of 120 PUTs were operated upon in 100 patients. PUT was bilateral in 15 patients, right-sided in 55 cases and left-sided in 30 cases. Among 120 testes 40 testes were located distal to external inguinal ring (EIR), 70 testes were at internal inguinal ring (IIR) and 10 testes were in between EIR and IIR. A total of 100 patients were successfully placed within scrotum using a single incision. Operative time ranged from 20-36 minutes. There were no cases of testicular atrophy or ascent. The only complications were 3 wound infections (3%), which were successfully treated with antibiotics. Single high transverse scrotal incision was sufficient to deal with PUT especially, in young infants (age 6 months). The procedure results in shorter operative times, similar success and complication rates, and a more cosmetically appealing outcome compared to inguinal orchiopexy.

Outcomes of repeat two-stage exchange hip arthroplasty for prosthetic joint infection

Aims

The increasing infection burden after total hip arthroplasty (THA) has seen a rise in the use of two-stage exchange arthroplasty and the use of increasingly powerful antibiotics at the time of this procedure. As a result, there has been an increase in the number of failed two-stage revisions during the past decade. The aim of this study was to clarify the outcome of repeat two-stage revision THA following a failed two-stage exchange due to recurrent prosthetic joint infection (PJI).

Patients and Methods

We identified 42 patients who underwent a two-stage revision THA having already undergone at least one previous two stage procedure for infection, between 2000 and 2015. There were 23 women and 19 men. Their mean age was 69.3 years (48 to 81). The outcome was analyzed at a minimum follow-up of two years.

Results

A satisfactory control of infection and successful outcome was seen in 26 patients (57%). There therefore remained persistent symptoms that either required further surgery or chronic antibiotic suppression in 16 patients (38%). One-third of patients had died by the time of two years’ follow-up.

Conclusion

The rate of failure and complication rate of repeat two-stage exchange THA for PJI is high and new methods of treatment including host optimization, immunomodulation, longer periods between stages, and new and more powerful forms of antimicrobial treatment should be investigated. Cite this article: Bone Joint J 2019;101-B(6 Supple B):110–115.

Routine ultrasound at 32 vs 36 weeks' gestation: prediction of small-for-gestational-age neonates

OBJECTIVE

To evaluate and compare the performance of routine ultrasonographic estimated fetal weight (EFW) and fetal abdominal circumference (AC) at 31 + 0 to 33 + 6 and 35 + 0 to 36 + 6 weeks' gestation in the prediction of a small-for-gestational-age (SGA) neonate.

METHODS

This was a prospective study of 21 989 singleton pregnancies undergoing routine ultrasound examination at 31 + 0 to 33 + 6 weeks' gestation and 45 847 undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. In each case, the estimated fetal weight (EFW) from measurements of fetal head circumference, AC and femur length was calculated using the Hadlock formula and expressed as a percentile according to The Fetal Medicine Foundation fetal and neonatal population weight charts. The same charts were used for defining a SGA neonate with birth weight < 10^th and < 3^rd percentiles. For each gestational-age window, the screen-positive and detection rates, at different EFW percentile cut-offs between the 10^th and 50^th percentiles, were calculated for prediction of delivery of a SGA neonate with birth weight < 10^th and < 3^rd percentiles within 2 weeks and at any stage after assessment. The areas under the receiver-operating characteristics curves (AUC) in screening for a SGA neonate by EFW and AC at 31 + 0 to 33 + 6 and at 35 + 0 to 36 + 6 weeks' gestation were compared.

RESULTS

First, the AUCs in screening by EFW for a SGA neonate with birth weight < 10^th and < 3^rd percentiles delivered within 2 weeks and at any stage after screening at 35 + 0 to 36 + 6 weeks' gestation were significantly higher than those at 31 + 0 to 33 + 6 weeks (P < 0.001). Second, at both 35 + 0 to 36 + 6 and 31 + 0 to 33 + 6 weeks' gestation, the predictive performance for a SGA neonate with birth weight < 10^th and < 3^rd percentiles born at any stage after screening was significantly higher using EFW Z-score than AC Z-score. Similarly, at 35 + 0 to 36 + 6 weeks, but not at 31 + 0 to 33 + 6 weeks, the predictive performance for a SGA neonate with birth weight < 10^th and < 3^rd percentiles born within 2 weeks after screening was significantly higher using EFW Z-score than AC Z-score. Third, screening by EFW < 10^th percentile at 35 + 0 to 36 + 6 weeks' gestation predicted 70% and 84% of neonates with birth weight < 10^th and < 3^rd percentiles, respectively, born within 2 weeks after assessment, and the respective values for a neonate born at any stage after assessment were 46% and 65%. Fourth, prediction of > 85% of SGA neonates with birth weight < 10^th percentile born at any stage after screening at 35 + 0 to 36 + 6 weeks' gestation requires use of EFW < 40^th percentile. Screening at this percentile cut-off predicted 95% and 99% of neonates with birth weight < 10^th and < 3^rd percentiles, respectively, born within 2 weeks after assessment, and the respective values for a neonate born at any stage after assessment were 87% and 94%.

CONCLUSIONS

The predictive performance for a SGA neonate of routine ultrasonographic examination during the third trimester is higher if, first, the scan is carried out at 35 + 0 to 36 + 6 weeks' gestation than at 31 + 0 to 33 + 6 weeks, second, the method of screening is EFW than fetal AC, third, the outcome measure is birth weight < 3^rd than < 10^th percentile, and, fourth, if delivery occurs within 2 weeks than at any stage after assessment. Prediction of a SGA neonate by EFW < 10^th percentile is modest and prediction of > 85% of cases at 35 + 0 to 36 + 6 weeks' gestation necessitates use of EFW < 40^th percentile. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Targeting checkpoint kinases in prostate cancer cells resistant to poly ADP-ribose polymerase inhibitors

e16543

Background: The identification of DNA damage response (DDR) gene abnormalities in various cancers has provided potential therapeutic targets including the poly ADP-ribose polymerase enzyme (PARP). PARP inhibitors are now approved for use in ovarian, breast, and prostate cancer (PC). Olaparib and rucaparib have been given Breakthrough Therapy designation by the FDA for use in patients with metastatic castration-resistant prostate cancer and germline BRCA1/2 or ATM mutations. However, drug resistance limits the efficacy of PARPi. Somatic reversion mutations of BRCA1/2 have been described as one potential mechanism of resistance to PARPi in patients with germline BRCA1/2 mutations. However, in PC, the BRCA2 gene is frequently deleted, in contrast to other cancers, where it is mutated. Thus, we hypothesize that resistance to PARPi in PC may involve alternative molecular mechanisms. Methods: We performed cell viability assays to determine the inhibitory growth (IG) concentrations of olaparib and talazoparib on human castration-resistant PC cell lines (PC-3 and LNCaP-Abl) that have heterozygous genomic deletions of BRCA2. Parental PC-3 cells were cultured in sublethal concentrations (IG 50% and IG 90%) of talazoparib-supplemented media for approximately 2 months to develop talazoparib-resistant cells. We then performed an analysis of phosphorylation status in untreated and treated parental PC-3 and talazoparib-resistant clones with a phosphokinase array. We confirmed this with Western blot. Results: Talazoparib-resistant PC-3 clones showed significantly enhanced cell growth compared to parental cells when cultured in media supplemented with the IG 90% concentration of talazoparib or olaparib. The phosphokinase array revealed a significant increase in the phosphorylation of CHEK2 in talazoparib-resistant clones compared to parental PC-3 cells. Interestingly, a similar increase was seen after 72 hours of treatment with talazoparib, indicating an early connection between PARP inhibition and CHEK2 phosphorylation in PC cells. Moreover, a pan-CHEK inhibitor, prexasertib, led to significant cell growth inhibition in talazoparib-resistant PC-3 clones and a significantly lower IG 50% concentration compared to parental PC-3 cells. Conclusions: We speculate that early activation of CHEK2 may be a primary mechanism of resistance to PARPi in PC cells with deletion of BRCA2. Furthermore, our preliminary data showed that CHEK inhibition can overcome PARPi resistance, indicating a potential for CHEK inhibitor-based therapy for PC patients.

Comprehensive Genomic Analysis of Metastatic Non-Clear-Cell Renal Cell Carcinoma to Identify Therapeutic Targets

PURPOSE

Non-clear-cell renal cell carcinoma (nccRCC) encompasses approximately 20% of renal cell carcinomas and includes subtypes that vary in clinical and molecular biology. Compared with clear cell renal cell carcinoma, nccRCC demonstrates limited sensitivity to conventional vascular endothelial growth factor- and mammalian target of rapamycin-directed agents, indicating a need for better therapies. Characterizing the genomic landscape of metastatic nccRCC variants may help define novel therapeutic strategies.

PATIENTS AND METHODS

We retrospectively analyzed tumor tissue from patients with metastatic nccRCC who consented to genomic analysis of their tumor and germline DNA. A hybridization capture-based assay was used to identify single nucleotide variants and small insertions and deletions across more than 340 cancer-associated genes with germline comparison. Clinical actionability of somatic mutations was assessed using OncoKB levels of evidence. Microsatellite instability (MSI) in the tumor was investigated.

RESULTS

Of 116 patients included in the analysis, 57 (49%) presented with de novo metastatic disease, and 59 (51%) presented with localized disease that later metastasized. Subtype classifications included unclassified (n = 41; 35%), papillary (n = 26; 22%), chromophobe (n = 17; 15%), translocation associated (n = 13; 11%), and other (n = 19; 16%). Of all tumors, 15 (13%) had putative driver somatic alterations amenable to targeted therapies, including alterations in MET, TSC1/2, and an ALK translocation. Of 45 patients who had germline testing, 11 (24%) harbored mutations, seven of which could potentially guide therapy. Of 115 available tumors for analysis, two (1.7%) had high and six (5%) had intermediate MSI status.

CONCLUSION

The mutation profiles of metastatic nccRCC vary by subtype. Comprehensive analysis of somatic mutations, germline mutations, and MSI, interpreted via an annotated precision oncology knowledge base, identified potentially targetable alterations in 22% of patients, which merits additional investigation.

A Novel Mechanism Driving Poor-Prognosis Prostate Cancer: Overexpression of the DNA Repair Gene, Ribonucleotide Reductase Small Subunit M2 (RRM2)

PURPOSE

Defects in genes in the DNA repair pathways significantly contribute to prostate cancer progression. We hypothesize that overexpression of DNA repair genes may also drive poorer outcomes in prostate cancer. The ribonucleotide reductase small subunit M2 (RRM2) is essential for DNA synthesis and DNA repair by producing dNTPs. It is frequently overexpressed in cancers, but very little is known about its function in prostate cancer.

EXPERIMENTAL DESIGN

The oncogenic activity of RRM2 in prostate cancer cells was assessed by inhibiting or overexpressing RRM2. The molecular mechanisms of RRM2 function were determined. The clinical significance of RRM2 overexpression was evaluated in 11 prostate cancer clinical cohorts. The efficacy of an RRM2 inhibitor (COH29) was assessed in vitro and in vivo. Finally, the mechanism underlying the transcriptional activation of RRM2 in prostate cancer tissue and cells was determined.

RESULTS

Knockdown of RRM2 inhibited its oncogenic function, whereas overexpression of RRM2 promoted epithelial mesenchymal transition in prostate cancer cells. The prognostic value of RRM2 RNA levels in prostate cancer was confirmed in 11 clinical cohorts. Integrating the transcriptomic and phosphoproteomic changes induced by RRM2 unraveled multiple oncogenic pathways downstream of RRM2. Targeting RRM2 with COH29 showed excellent efficacy. Thirteen putative RRM2-targeting transcription factors were bioinformatically identified, and FOXM1 was validated to transcriptionally activate RRM2 in prostate cancer.

CONCLUSIONS

We propose that increased expression of RRM2 is a mechanism driving poor patient outcomes in prostate cancer and that its inhibition may be of significant therapeutic value.