Novel Inhibitors of androgen receptor's DNA binding domain identified using an ultra-large virtual screening

Androgen receptor (AR) inhibition remains the primary strategy to combat the progression of prostate cancer (PC). However, all clinically used AR inhibitors target the ligand-binding domain (LBD), which is highly susceptible to truncations through splicing or mutations that confer drug resistance. Thus, there exists an urgent need for AR inhibitors with novel modes of action. We thus launched a virtual screening of an ultra-large chemical library to find novel inhibitors of the AR DNA-binding domain (DBD) at two sites: protein-DNA interface (P-box) and dimerization site (D-box). The compounds selected through vigorous computational filtering were then experimentally validated. We identified several novel chemotypes that effectively suppress transcriptional activity of AR and its splice variant V7. The identified compounds represent previously unexplored chemical scaffolds with a mechanism of action that evades the conventional drug resistance manifested through LBD mutations. Additionally, we describe the binding features required to inhibit AR DBD at both P-box and D-box target sites.

Structure-Based Study to Overcome Cross-Reactivity of Novel Androgen Receptor Inhibitors

The mutation-driven transformation of clinical anti-androgen drugs into agonists of the human androgen receptor (AR) represents a major challenge for the treatment of prostate cancer patients. To address this challenge, we have developed a novel class of inhibitors targeting the DNA-binding domain (DBD) of the receptor, which is distanced from the androgen binding site (ABS) targeted by all conventional anti-AR drugs and prone to resistant mutations. While many members of the developed 4-(4-phenylthiazol-2-yl)morpholine series of AR-DBD inhibitors demonstrated the effective suppression of wild-type AR, a few represented by 4-(4-(3-fluoro-2-methoxyphenyl)thiazol-2-yl)morpholine (VPC14368) exhibited a partial agonistic effect toward the mutated T878A form of the receptor, implying their cross-interaction with the AR ABS. To study the molecular basis of the observed cross-reactivity, we co-crystallized the T878A mutated form of the AR ligand binding domain (LBD) with a bound VPC14368 molecule. Computational modelling revealed that helix 12 of AR undergoes a characteristic shift upon VPC14368 binding causing the agonistic behaviour. Based on the obtained structural data we then designed derivatives of VPC14368 to successfully eliminate the cross-reactivity towards the AR ABS, while maintaining significant anti-AR DBD potency.

Abstract 5731: Structure-based development of a novel MYC inhibitor for neuroendocrine prostate cancer

Background: MYC oncoproteins are important drivers of human cancers. More specifically, NMYC is amplified and overexpressed in neuroendocrine prostate cancer (NEPC). NMYC elicits its oncogenic effects by forming a heterodimer with MAX. This complex binds to regulating elements and activates the transcription of MYC target genes that play roles in tumor growth and progression. It is well known that members of the MYC family of proteins make compelling targets for cancer treatments. However, to this date, no tangible drug candidates have been developed into the clinics for MYC. In previous studies utilizing a rational computer-aided drug discovery (CADD) approach, we identified VPC-70551 as our most active hit. Subsequent optimization with the VPC-70551 scaffold has led to the identification of a new series of compounds. Using in silico drug screening followed by functional validation, we identified a small molecule inhibitor, VPC-70619, that exhibits higher microsomal stability and is better absorbed and tolerated orally than most MYC inhibitors described in the literature.

Method: We used a transcriptional reporter assay to determine the effect of VPC-70619 on MYC-mediated transcription. To validate on-target effect, we evaluated the effect of VPC-70619 treatment on MYC-positive (LASCPC-01, NCIH660, LNCaP N-MYC, 22Rv1 N-MYC) and MYC-negative (HO15.19) cancer cells. We also evaluated the effect of VPC-70619 on MYC/MAX interaction by PLA and on DNA binding by BLI. The direct binding between recombinant MYC/MAX protein complex and VPC-70619 was evaluated by MST.

Results: VPC-70619 inhibited MYC transcriptional activity in dose dependent manner and the proliferation of MYC-positive cell lines. VPC-70619 did not interfere with MYC/MAX interaction however it blocked the complex interaction with DNA. We confirmed the direct binding of VPC-70619 to the purified MYC/MAX complex by using MST.

Conclusion: This project presents the identification of a new MYC inhibitor that blocks the transcriptional activity of this oncogene and elucidates the molecular mechanism of action of this inhibitor. Our findings help prelude the development and discovery of more effective treatments for NEPC patients.

Citation Format: Jane Foo, Anh-Tien Ton, Kriti Singh, Fuqiang Ban, Helene Morin, Joseph Lee, Eric LeBlanc, Nada Lallous, Artem Cherkasov. Structure-based development of a novel MYC inhibitor for neuroendocrine prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5731.

Reproductive history and osteoarthritis in the Women's Health Initiative

Objective: To investigate the relationship between self-reported osteoarthritis (OA) and reproductive factors in the Women's Health Initiative (WHI). Method: We used multivariable logistic regression to study the association of self-reported OA and reproductive factors in the WHI Observational Study and Clinical Trial cohorts of 145 965 postmenopausal women, in a retrospective cross-sectional format. Results: In our cohort, we observed no clinically significant associations between reproductive factors and OA given small effect sizes. The following factors were associated with statistically significant increased likelihood of developing OA: younger age at menarche (p < 0.001), history of hysterectomy [adjusted odds ratio (aOR) 1.013, 95% confidence interval (CI) 1.004-1.022, p = 0.04 vs no hysterectomy], history of unilateral oophorectomy (aOR 1.015, 95% CI 1.004-1.026, p < 0.01 vs no oophorectomy), parity (aOR 1.017, 95% CI 1.009-1.026, p < 0.001), ever use of oral contraceptives (aOR 1.008, 95% CI 1.001-1.016, p < 0.01 vs never use), and current use of hormonal therapy (reference current users, aOR 0.951, 95% CI 0.943-0.959 for never users; aOR 0.981, 95% CI 0.972-0.989 for past users; global p < 0.001). Age at menopause, first birth, and pregnancy were not associated with OA. Among parous women, no clear pattern was observed with number of pregnancies, births, or duration of breastfeeding in relation to OA. Conclusion: Our study showed that reproductive factors did not have significant clinical associations with OA after controlling for confounders. This may be due to complex hormonal effects. Additional investigation is warranted in prospective cohort studies. The Women's Health Initiative is registered under ClinicalTrials.gov. Trial registration ID: NCT00000611.

Computer-Aided Discovery of Small Molecule Inhibitors of Transcriptional Activity of TLX (NR2E1) Nuclear Receptor

Orphan nuclear receptor TLX (NR2E1) plays a critical role in the regulation of neural stem cells (NSC) as well as in the development of NSC-derived brain tumors. In the last years, new data have emerged implicating TLX in prostate and breast cancer. Therefore, inhibitors of TLX transcriptional activity may have a significant impact on the treatment of several critical malignancies. However, the TLX protein possesses a non-canonical ligand-binding domain (LBD), which lacks a ligand-binding pocket (conventionally targeted in case of nuclear receptors) that complicates the development of small molecule inhibitors of TLX. Herein, we utilized a rational structure-based design approach to identify small molecules targeting the Atro-box binding site of human TLX LBD. As a result of virtual screening of ~7 million molecular structures, 97 compounds were identified and evaluated in the TLX-responsive luciferase reporter assay. Among those, three chemicals demonstrated 40–50% inhibition of luciferase-detected transcriptional activity of the TLX orphan nuclear receptor at a dose of 35 µM. The identified compounds represent the first class of small molecule inhibitors of TLX transcriptional activity identified via methods of computer-aided drug discovery.

Selectively targeting the dimerization interface of human androgen receptor with small-molecules to treat castration-resistant prostate cancer

Prostate cancer (PCa) is a leading cause of death for men in North America. The androgen receptor (AR) - a hormone inducible transcription factor - drives expression of tumor promoting genes and represents an important therapeutic target in PCa. The AR is activated by steroid recruitment to its ligand binding domain (LBD), followed by receptor nuclear translocation and dimerization via the DNA binding domain (DBD). Clinically used small molecules interfere with steroid recruitment and prevent AR-driven tumor growth, but are rendered ineffective by emergence of LBD mutations or expression of constitutively active variants, such as ARV7, that lack the LBD. Both drug-resistance mechanisms confound treatment of this 'castration resistant' stage of PCa (CRPC), characterized by return of AR signalling. Here, we employ computer-aided drug-design to develop small molecules that block the AR-DBD dimerization interface, an attractive target given its role in AR activation and independence from the LBD. Virtual screening on the AR-DBD structure led to development of prototypical compounds that block AR dimerization, inhibiting AR-transcriptional activity through a LBD-independent mechanism. Such inhibitors may potentially circumvent AR-dependent resistance mechanisms and directly target CRPC tumor growth.

Small molecule-induced degradation of the full length and V7 truncated variant forms of human androgen receptor

The androgen receptor (AR) is a hormone-activated transcription factor that regulates the development and progression of prostate cancer (PCa) and represents one of the most well-established drug targets. Currently clinically approved small molecule inhibitors of AR, such as enzalutamide, are built upon a common chemical scaffold that interacts with the AR by the same mechanism of action. These inhibitors eventually fail due to the emergence of drug-resistance in the form of AR mutations and expression of truncated AR splice variants (e.g. AR-V7) that are constitutively active, signalling the progression of the castration-resistant state of the disease. The urgent need therefore continues for novel classes of AR inhibitors that can overcome drug resistance, especially since AR signalling remains important even in late-stage advanced PCa. Previously, we identified a collection of 10-benzylidene-10H-anthracen-9-ones that effectively inhibit AR transcriptional activity, induce AR degradation and display some ability to block recruitment of hormones to the receptor. In the current work, we extended the analysis of the lead compounds, and used methods of both ligand- and structure-based drug design to develop a panel of novel 10-benzylidene-10H-anthracen-9-one derivatives capable of suppressing transcriptional activity and protein expression levels of both full length- and AR-V7 truncated forms of human androgen receptor. Importantly, the developed compounds efficiently inhibited the growth of AR-V7 dependent prostate cancer cell-lines which are completely resistant to all current anti-androgens.

Cheminformatics Driven Development of Novel Therapies for Drug Resistant Prostate Cancer

Androgen receptor (AR) is a master regulator of prostate cancer (PCa), and therefore is a pivotal drug target for the treatment of PCa including its castration-resistance form (CRPC). The development of acquired resistance is a major challenge in the use of the current antiandrogens. The recent advancements in inhibiting AR activity with small molecules specifically designed to target areas distinct from the receptor's androgen binding site are carefully discussed. Our new classes of AR inhibitors of AF2 and BF3 functional sites and DBD domains designed using cheminformatics techniques are promising to circumvent various AR-dependent resistance mechanisms.

Bypassing Drug Resistance Mechanisms of Prostate Cancer with Small Molecules that Target Androgen Receptor-Chromatin Interactions

Human androgen receptor (AR) is a hormone-activated transcription factor that is an important drug target in the treatment of prostate cancer. Current small-molecule AR antagonists, such as enzalutamide, compete with androgens that bind to the steroid-binding pocket of the AR ligand-binding domain (LBD). In castration-resistant prostate cancer (CRPC), drug resistance can manifest through AR-LBD mutations that convert AR antagonists into agonists, or by expression of AR variants lacking the LBD. Such treatment resistance underscores the importance of novel ways of targeting the AR. Previously, we reported the development of a series of small molecules that were rationally designed to selectively target the AR DNA-binding domain (DBD) and, hence, to directly interfere with AR-DNA interactions. In the current work, we have confirmed that the lead AR DBD inhibitor indeed directly interacts with the AR-DBD and tested that substance across multiple clinically relevant CRPC cell lines. We have also performed a series of experiments that revealed that genome-wide chromatin binding of AR was dramatically impacted by the lead compound (although with lesser effect on AR variants). Collectively, these observations confirm the novel mechanism of antiandrogen action of the developed AR-DBD inhibitors, establishing proof of principle for targeting DBDs of nuclear receptors in endocrine cancers. Mol Cancer Ther; 16(10); 2281-91. ©2017 AACR.

Best Practices of Computer-Aided Drug Discovery: Lessons Learned from the Development of a Preclinical Candidate for Prostate Cancer with a New Mechanism of Action

Small-molecule drug design is a complex and iterative decision-making process relying on pre-existing knowledge and driven by experimental data. Low-molecular-weight chemicals represent an attractive therapeutic option, as they are readily accessible to organic synthesis and can easily be characterized.1 Their potency as well as pharmacokinetic and pharmacodynamic properties can be systematically and rationally investigated and ultimately optimized via expert science behind medicinal chemistry and methods of computer-aided drug design (CADD). In recent years, significant advances in molecular modeling techniques have afforded a variety of tools to effectively identify potential binding pockets on prospective targets, to map key interactions between ligands and their binding sites, to construct and assess energetics of the resulting complexes, to predict ADMET properties of candidate compounds, and to systematically analyze experimental and computational data to derive meaningful structure-activity relationships leading to the creation of a drug candidate. This Perspective describes a real case of a drug discovery campaign accomplished in a relatively short time with limited resources. The study integrated an arsenal of available molecular modeling techniques with an array of experimental tools to successfully develop a novel class of potent and selective androgen receptor inhibitors with a novel mode of action. It resulted in the largest academic licensing deal in Canadian history, totaling $142M. This project exemplifies the importance of team science, an integrative approach to drug discovery, and the use of best practices in CADD. We posit that the lessons learned and best practices for executing an effective CADD project can be applied, with similar success, to many drug discovery projects in both academia and industry.

Abstract 4644: Inhibition of the androgen receptor at two drug-targetable sites on the DNA-binding domain protein surface

The androgen receptor (AR) is a hormone inducible transcription factor that continues to be an important drug-target to prevent or slow the progression of prostate cancer. Current small molecule inhibitors, such as Enzalutamide (anti-androgens), compete with naturally occurring steroids that bind to the hormone binding pocket of the AR ligand binding domain (LBD). In advanced or castration resistant prostate cancer (CRPC), mutations in the LBD confer drug-resistance by converting anti-androgens into agonists, prompting research to develop small molecule inhibitors that target different sites on the AR protein surface. Recently, we characterized a set of small molecules that could interact with the DNA binding domain (DBD) of the AR and block its transcriptional activity. Here, we extend the pioneering observations by clarifying the mechanism of two classes of compounds that either block AR-chromatin interactions or reduce AR-dimerization in the cell nucleus. Compound efficacy is demonstrated across multiple prostate cancer cells lines, including enzalutamide resistant forms, with respect to AR transactivation, cell viability and expression of downstream genes. We also characterize the pharmacological properties of the lead compound and its effects on tumour xenografts in mice. Collectively, these results lay the foundation for the development of alternative prostate cancer drugs that interfere with the biochemical function of the activated, nuclear localized AR.

Citation Format: Kush Dalal, Aishwariya Sharma, Mani Roshan-Moniri, Hendrik Borgmann, Nada Lallous, Shannon Awrey, Huifang Li, Fuqiang Ban, Eric LeBlanc, Artem Cherkasov, Paul S. Rennie. Inhibition of the androgen receptor at two drug-targetable sites on the DNA-binding domain protein surface. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4644.

Abstract 1648: Targeting ETS factor ETV4 as a novel therapeutic for the management of breast and prostate cancer

Despite the development of several successful targeted therapies, drug resistance and metastasis remain a significant challenge in the treatment of both breast (BCa) and prostate (PCa) cancers. For these reasons, there is an immediate need to identify a novel class of therapeutics targeting alternative factors, such as those that promote the metastatic capacity of tumour cells. ETS translocation variant 4 (ETV4) is a member of the ETS transcription factor family and is a significant mediator of tumorigenesis through its activation of several downstream pathways that are associated with migration and invasion. ETV4 is overexpressed in breast tumours and is associated with distant metastasis and poor prognosis particularly in triple negative BCa, which still lacks an approved targeted therapy. Similarly in PCa, overexpression of ETV4 is associated with the deregulation of the PI3K and Ras signalling pathways that are commonly implicated in metastatic disease. Like other ETS factors such as ERG and ETV1, fusion of the ETV4 gene can be found in a subtype of PCa cases and is associated with the disease progression. Thus, ETV4 is an important therapeutic candidate with potential applications in both advanced BCa and PCa. Drug development against ETV4 is made even more significant due to the lack of any approved therapy that directly targets it or any other members of the ETS family. Using a combination of in silico screening and in vitro assays, we have identified several small molecules with strong binding affinities and selectivity toward the DNA binding domain of ETV4. The prostate cell line, PC3, and the triple negative breast cancer cell line, MDA-MB-231, were used for in vitro studies as they endogenously express moderate to high levels of ETV4. Over 100 candidate compounds, which were selected from virtual screening against millions of small-molecular structures, were tested across the two cell lines using a luciferase-based transcriptional reporter assay. From this assay approximately 30 compounds were identified with significant inhibition on the transcriptional activity of ETV4 without a cytotoxic effect. The most potent of these compounds was shown by protein nuclear magnetic resonance (NMR) to directly interact with specific residues within the DNA binding domain. These compounds were also able to inhibit the migratory capacity of cancer cells. This data provides evidence for the direct targeting of ETV4 by small molecules, and future work will aim to further characterize their mechanism of action and effects on downstream targets in an effort to create a novel therapeutic strategy to treat metastatic breast and prostate cancers. (Supported by grants from the Canadian Cancer Society Research Initiative and Prostate Cancer Canada)

Citation Format: Miriam S. Butler, Michael Hsing, Mani Roshan Moniri, Desmond Lau, Paul Yen, Ari Kim, Scott Lien, Marta Mroczek, Fariba Ghaidi, Eric LeBlanc, Lawrence McIntosh, Michael Cox, Artem Cherkasov, Paul S. Rennie. Targeting ETS factor ETV4 as a novel therapeutic for the management of breast and prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1648. doi:10.1158/1538-7445.AM2015-1648

Abstract 1652: Therapeutic targeting of ETS factor ERG for the treatment of prostate cancer

Prostate cancer (PCa) is one of the leading causes of cancer-related death in men worldwide. The common treatment option for recurring and advanced PCa focuses on inhibiting the androgen receptor (AR). Unfortunately, despite an initial response to this treatment, drug resistance occurs, and the cancer relapses to an incurable, castration-resistant form; thus, there is a pressing need for new therapeutics. Previous research has shown that in up to 50% of all prostate cancer cases, the cause of the disease may be attributed to a common genomic rearrangement, the fusion between TMPRSS2 and ERG (ETS-related gene). ERG is a transcription factor mainly involved in hematopoiesis regulation during embryonic development, and it is not normally expressed in prostate cells in adults. However, its fusion with the TMPRSS2 promoter puts ERG under the regulation of AR, and as a consequence, ERG is one of the most commonly overexpressed genes in PCa. ERG overexpression in prostate epithelium has been shown to induce transformation and promote epithelial-mesenchymal transition (EMT) that gives cancer cells enhanced migratory and invasive characteristics. Currently, there is no approved therapeutic targeting ERG or any other member of the ETS family. While targeting transcription factors has been challenging, our integrated research team is specialized in targeting protein-DNA interaction sites. Using our established computer-aided drug discovery pipeline, we have identified several small molecules that can bind to and inhibit ERG. A total of 133 candidate compounds, pre-selected from the in silico screening of millions of chemical structures, were tested using a luciferase-based transcriptional reporter assay across two cell lines: the TMPRSS2-ERG fusion positive VCaP cell line, and the human prostate epithelial cell line (PNT1B) engineered to constitutively express ERG. In addition to transcriptional inhibition, the most potent compounds inhibited migration of PNT1B-ERG cells as demonstrated by a Real-Time Cell Analyzer. Significantly, both compounds shifted the binding spectra in protein NMR assays, indicating their direct interactions with residues located in the DNA binding domain of the ERG protein. We anticipate that results from this project will lead to the development of new drugs that can be used alternatively or synergistically with current anti-AR therapy to benefit patients with the most deadly forms of prostate cancer. (Supported by a grant from Prostate Cancer Canada)

Citation Format: Mani Roshan-Moniri, Michael Hsing, Miriam S. Butler, Desmond Lau, Peter Axerio-Cilies, Paul Yen, Ari Kim, Scott Lien, Marta Mroczek, Dennis Ma, Huifang Li, Yubin Guo, Fuqiang Ban, Fariba Ghaidi, Eric LeBlanc, Lawrence McIntosh, Michael Cox, Artem Cherkasov, Paul S. Rennie. Therapeutic targeting of ETS factor ERG for the treatment of prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1652. doi:10.1158/1538-7445.AM2015-1652

Selectively targeting the DNA-binding domain of the androgen receptor as a prospective therapy for prostate cancer

The androgen receptor (AR) is a transcription factor that has a pivotal role in the occurrence and progression of prostate cancer. The AR is activated by androgens that bind to its ligand-binding domain (LBD), causing the transcription factor to enter the nucleus and interact with genes via its conserved DNA-binding domain (DBD). Treatment for prostate cancer involves reducing androgen production or using anti-androgen drugs to block the interaction of hormones with the AR-LBD. Eventually the disease changes into a castration-resistant form of PCa where LBD mutations render anti-androgens ineffective or where constitutively active AR splice variants, lacking the LBD, become overexpressed. Recently, we identified a surfaced exposed pocket on the AR-DBD as an alternative drug-target site for AR inhibition. Here, we demonstrate that small molecules designed to selectively bind the pocket effectively block transcriptional activity of full-length and splice variant AR forms at low to sub-micromolar concentrations. The inhibition is lost when residues involved in drug interactions are mutated. Furthermore, the compounds did not impede nuclear localization of the AR and blocked interactions with chromatin, indicating the interference of DNA binding with the nuclear form of the transcription factor. Finally, we demonstrate the inhibition of gene expression and tumor volume in mouse xenografts. Our results indicate that the AR-DBD has a surface site that can be targeted to inhibit all forms of the AR, including enzalutamide-resistant and constitutively active splice variants and thus may serve as a potential avenue for the treatment of recurrent and metastatic prostate cancer.

Abstract 1070: New potent inhibitors of the androgen receptor that target its BF3 surface binding site

In the development and progression of prostate cancer, the androgen receptor (AR) plays a critical role and its hormone/ligand-binding site is the primary therapeutic target for all antiandrogens (eg Bicalutamide, MDV3100) currently used to treat advanced, metastatic forms of this disease. While treatment with these AR inhibitors initially suppresses prostate tumor growth, resistance to these drugs invariably emerges. Accordingly, there exists a clinical need for the development of new AR antagonists with different chemical structures and different mechanisms of action for targeting and inhibiting AR transactivation. To this end, we have focused on a surface pocket on the AR called Binding Function 3 (BF3). Applying iterative in silico screening to millions of chemicals in the ZINC database, coupled with biological screening for AR binding and activity, we identified several compounds that can bind directly to the BF3 pocket and inhibit AR transactivation. Cell-based screening assays for inhibition of a fluorescent ARE-reporter and PSA expression, together with Biolayer Interferometry analysis for measuring binding to the AR, revealed several chemically distinct BF-3 binders that showed significant IC50 inhibitions of the AR in the nano-molar to low micro-molar range. Validation for binding to the BF3 site was performed by x-ray crystallography. Furthermore, none of these compounds were able to displace DHT from the hormone binding site even at concentrations more than 10-fold higher than their IC50 values. In addition to wild type LNCaP prostate cancer cells, these BF3 binders effectively inhibited cell proliferation (MTS assay) and PSA expression in derived MDV3100-resistant prostate cancer cell lines, but had no effect on cell viability of AR-negative prostate cancer cell lines. In summary, we have identified an entirely new class of anti-androgens that bind to the BF3 surface site of the AR and inhibit its transactivation by a mechanism which does not involve binding to its hormone/ligand binding site and thereby bypasses the treatment resistance seen with conventional antiandrogens. (Supported by funds from the PCF, Canada Safeway, and CIHR).

Citation Format: Ravi Munuganti, Fuqiang Ban, Huifang Li, Eric LeBlanc, Peter Axerio, Kate Frewin, Emma Tomlinson Guns, Artem Cherkasov, Paul S. Rennie. New potent inhibitors of the androgen receptor that target its BF3 surface binding site. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1070. doi:10.1158/1538-7445.AM2013-1070

Use of a computerized tracking system to monitor and provide feedback on dietary goals for calorie-restricted diets: the POUNDS LOST study

The use of self-monitoring as a tool to facilitate behavioral modification is common in many lifestyle-based weight loss interventions. Electronic tracking programs, including computer-based systems and smart phone applications, have been developed to allow individuals to self-monitor their behavior digitally. These programs offer an advantage over traditional self-report modalities in that they can provide users with direct feedback about dietary and/or physical activity adherence levels and thereby assist them in real-time decision making. This article describes the use of an Internet-based computerized tracking system (CTS) that was developed specifically for the POUNDS LOST study, a 2-year randomized controlled trial designed to test the efficacy of four macronutrient diets for weight and fat reduction in healthy, overweight men and women (body mass index range = 25.0-39.9 kg/m(2)). The CTS served many functions in this study, including data collection, dietary and exercise assessment and feedback, messaging system, and report generation. Across all groups, participants with high usage of the CTS during the initial 8 weeks lost greater amounts of weight than participants with low usage (8.7% versus 5.5% of initial body weight, respectively; p < .001) at week 32. Rates of CTS utilization were highest during the first year of this 2-year intervention, and utilization of the CTS declined steadily over time. The unique features of the CTS combined with technological developments, such as smart phone applications, offer significant potential to improve the user's self-monitoring experience and adherence to health promotion programs designed specifically for individuals with obesity and type 2 diabetes.

Lipid nanoparticle siRNA systems for silencing the androgen receptor in human prostate cancer in vivo

The androgen receptor (AR) plays a critical role in the progression of prostate cancer. Silencing this protein using short-hairpin RNA (shRNA) has been correlated with tumor growth inhibition and decreases in serum prostate specific antigen (PSA). In our study, we have investigated the ability of lipid nanoparticle (LNP) formulations of small-interfering RNA (siRNA) to silence AR in human prostate tumor cell lines in vitro and in LNCaP xenograft tumors following intravenous (i.v.) injection. In vitro screening studies using a panel of cationic lipids showed that LNPs containing the ionizable cationic lipid 2,2-dilinoleyl-4-(2-dimethylaminoethyl)-[1,3]-dioxolane (DLin-KC2-DMA) exhibited the most potent AR silencing effects in LNCaP cells. This is attributed to an optimized ability of DLin-KC2-DMA-containing LNP to be taken up into cells and to release the siRNA into the cell cytoplasm following endocytotic uptake. DLin-KC2-DMA LNPs were also effective in silencing the AR in a wild-type AR expressing cell line, LAPC-4, and a variant AR expressing cell line, CWR22Rv1. Importantly, it is demonstrated that LNP AR-siRNA systems containing DLin-KC2-DMA can silence AR gene expression in distal LNCaP xenograft tumors and decrease serum PSA levels following i.v. injection. To our knowledge, this is the first report demonstrating the feasibility of LNP delivery of siRNA for silencing AR gene expression in vivo.

Targeting the binding function 3 (BF3) site of the human androgen receptor through virtual screening

The androgen receptor (AR) is the best studied drug target for the treatment of prostate cancer. While there are a number of drugs that target the AR, they all work through the same mechanism of action and are prone to the development of drug resistance. There is a large unmet need for novel AR inhibitors which work through alternative mechanism(s). Recent studies have identified a novel site on the AR called binding function 3 (BF3) that is involved into AR transcriptional activity. In order to identify inhibitors that target the BF3 site, we have conducted a large-scale in silico screen followed by experimental evaluation. A number of compounds were identified that effectively inhibited the AR transcriptional activity with no obvious cytotoxicity. The mechanism of action of these compounds was validated by biochemical assays and X-ray crystallography. These findings lay a foundation for the development of alternative or supplementary therapies capable of combating prostate cancer even in its antiandrogen resistant forms.

Adherence is a multi-dimensional construct in the POUNDS LOST trial

Research on the conceptualization of adherence to treatment has not addressed a key question: Is adherence best defined as being a uni-dimensional or multi-dimensional behavioral construct? The primary aim of this study was to test which of these conceptual models best described adherence to a weight management program. This ancillary study was conducted as a part of the POUNDS LOST trial that tested the efficacy of four dietary macronutrient compositions for promoting weight loss. A sample of 811 overweight/obese adults was recruited across two clinical sites, and each participant was randomly assigned to one of four macronutrient prescriptions: (1) Low fat (20% of energy), average protein (15% of energy); (2) High fat (40%), average protein (15%); (3) Low fat (20%), high protein (25%); (4) High fat (40%), high protein (25%). Throughout the first 6 months of the study, a computer tracking system collected data on eight indicators of adherence. Computer tracking data from the initial 6 months of the intervention were analyzed using exploratory and confirmatory analyses. Two factors (accounting for 66% of the variance) were identified and confirmed: (1) behavioral adherence and (2) dietary adherence. Behavioral adherence did not differ across the four interventions, but prescription of a high fat diet (vs. a low fat diet) was found to be associated with higher levels of dietary adherence. The findings of this study indicated that adherence to a weight management program was best conceptualized as being multi-dimensional, with two dimensions: behavioral and dietary adherence.

Radical vaginal trachelectomy (Dargent's operation): A critical review of the literature

AIMS

To present a review of the most recent articles about radical vaginal trachelectomy (RVT).

METHODS

Recent literature has been reviewed, concentrating on surgical, oncological and obstetrical outcome of RVT. Data for this review were identified by searches of PubMed, and references from relevant articles using the search terms "trachelectomy" and "radical vaginal trachelectomy", "cervical carcinoma", and "fertility saving".

FINDINGS

Although a considerable number of women in their reproductive years have been diagnosed with cervical carcinoma, conservative management of early-stage cervical carcinoma did not come into practice until the beginning of the new millennium. To date, 7 gynecologic oncologic centers worldwide have reported oncological and pregnancy outcomes since Dargent made his first announcement of radical vaginal trachelectomy (RVT) in 1994. Recurrence and death rates (4.2% and 2.8%, respectively) of RVT seem to be comparable to classical radical abdominal hysterectomy. It appears that RVT's overall recurrence and death rates were similar to early-stage cervical cancer treated by radical hysterectomy (RH) or radiotherapy. Furthermore fertility results of RVT seem to be promising. A 70% pregnancy rate was reported in the women who wanted to conceive following RVT, though such patients should be informed about the risk of second trimester loss and preterm delivery. On the other hand, there is a lack of satisfactory information about the follow-up of post-RVT patients, both after the operation and during subsequent pregnancy.

CONCLUSION

RVT looks as if it is a valid uterus-conserving surgery for women of reproductive age who have early-stage cervical carcinoma. However, in order to reach a final conclusion about the oncological and obstetrical results, further studies are needed with larger sample sizes and longer follow-up periods.

Global genetic diversity of human metapneumovirus fusion gene

We analyzed 64 human metapneumovirus strains from eight countries. Phylogenetic analysis identified two groups (A and B, amino acid identity 93%-96%) and four subgroups. Although group A strains predominated, accounting for 69% of all strains, as many B as A strains were found in persons >3 years of age.

Laparoscopic restaging of borderline ovarian tumours: results of 30 cases initially presumed as stage IA borderline ovarian tumours

OBJECTIVES

To review our experience with the laparoscopic restaging procedure of presumed early stage borderline ovarian tumours.

DESIGN

Retrospective study.

SETTING

Cancer centre.

POPULATION

Thirty patients with presumed stage I borderline ovarian tumours after limited initial surgery.

METHODS

From April 1991 to May 2001, the patients were laparoscopically reassessed. The procedure involved peritoneal cytology, exploration of the peritoneal cavity, infracolic omentectomy, directed or random peritoneal biopsies, and when appropriate, contralateral oophorectomy and hysterectomy and appendectomy. Medical records were reviewed for patients' age, interval time between procedures, tumour stage, histological type, operative time, hospital stay, peri-operative complications and follow up.

MAIN OUTCOME MEASURES

Seroperative and postoperative data, pathology and clinical follow up.

RESULTS

Laparoscopic restaging was completed in all 30 (100%) identified patients. The mean age was 34.8 (10.5) years; the delay between initial operation and restaging laparoscopy averaged 9.8 (6.6) weeks. The mean operative time was 165.4 (53.8) minutes, and the mean hospital stay was 2.7 (1.3) days. There were two (7.0%) major complications related directly to the procedure. Eight (26.6%) patients were upstaged. Mean follow up was 29.1 (6.6) months, all patients are alive and one (3.2%) recurrence was observed.

CONCLUSIONS

Laparoscopic approach of restaging for borderline ovarian tumours is an accurate safe procedure. It is associated with an acceptable rate of minor complications, it has similar morbidity associated with laparotomy and it minimises the incidence of infertility in the young patients. Whenever staging of borderline ovarian tumours is to be considered in an individual patient, laparoscopy provides a suitable alternative approach.

Extraperitoneal laparoscopic para-aortic lymph node dissection for early stage nonseminomatous germ cell tumors of the testis with introduction of a nerve sparing technique: description and results

PURPOSE

The extraperitoneal approach is well suited to urological surgery. Transperitoneal laparoscopic para-aortic lymph node dissection has been reported with good results for early stage nonseminomatous germ cell tumor of the testis. We report our current experience with laparoscopic para-aortic lymph node dissection using a new extraperitoneal approach.

MATERIALS AND METHODS

The technique consists of an internal iliac extraperitoneal approach and complete unilateral modified laparoscopic para-aortic lymph node dissection. We assessed 25 patients with clinical stage I (20) or IIA (5) testicular nonseminomatous germ cell tumor who underwent this technique, including left and right lymphadenectomy in 13 and 12, respectively. In addition, nerve sparing dissection was performed in the last 12 cases.

RESULTS

An average of 9.8 (range 3 to 19) and 17. 7 (range 5 to 29) lymph nodes were dissected on the right and left sides, respectively. No intraoperative or postoperative complications developed that required laparotomy. Average operative time was 3 hours 50 minutes (range 3 to 5 hours). Average hospital stay was 1.2 days (range 1 to 3). Results were positive in 10 patients who were given platinum based chemotherapy. At close followup of 15 months no late adverse effects or recurrence was observed.

CONCLUSIONS

Although a larger experience and longer followup are required, extraperitoneal laparoscopy is a safe, effective and well suited method of diagnostic para-aortic lymph node dissection for early stage testicular nonseminomatous germ cell tumor. The specific advantages of this approach are no blind trocar insertion or bowel contact and ability to perform nerve sparing dissection. Moreover, it is cost-effective since only 3 trocars are necessary and recovery is rapid.

De novo adhesions with extraperitoneal endosurgical para-aortic lymphadenectomy versus transperitoneal laparoscopic para-aortic lymphadenectomy: a randomized experimental study

OBJECTIVE

The objective of this study was to compare the risk of adhesion formation and the site of postoperative adhesions after transperitoneal versus extraperitoneal laparoscopic para-aortic lymphadenectomy.

STUDY DESIGN

A prospective study was conducted on 66 pigs, randomly allocated to 2 groups of 33 animals that underwent transperitoneal versus extraperitoneal laparoscopic para-aortic lymphadenectomy.

RESULTS

No statistically significant difference was observed between the 2 techniques in terms of operating time, number of lymph nodes removed, and intraoperative and postoperative morbidity. More lymphoceles were observed in the extraperitoneal laparoscopy group (P =.0002). The overall adhesion rates were 76% in the transperitoneal group and 43.33% in the extraperitoneal group (P =.04). The adhesion score specific to the operative site was lower in the extraperitoneal group (P =.0005). A stereolocalization study showed that almost all adhesions after transperitoneal laparoscopy were situated in the para-aortic external irradiation field, whereas adhesions after extraperitoneal laparoscopy were predominantly situated outside this field.

CONCLUSION

Extraperitoneal laparoscopy generates significantly fewer adhesions in the para-aortic irradiation field.

Learning curves for transperitoneal laparoscopic and extraperitoneal endoscopic paraaortic lymphadenectomy

STUDY OBJECTIVE

To compare learning curves for paraaortic lymphadenectomy by extraperitoneal endoscopic approach with those for transperitoneal laparoscopy.

DESIGN

Randomized, long-term study (Canadian Task Force classification I).

SETTING

Animal laboratory.

SUBJECTS

Sixty-six pigs.

INTERVENTION

Laparoscopic and endoscopic paraaortic lymphadenectomy, 33 pigs in each group, performed by two surgeons competent in laparoscopic surgery but without experience in endoscopic paraaortic lymphadenectomy.

MEASUREMENTS AND MAIN RESULTS

The duration of the procedure, number of lymph nodes removed, and number of residual nodes revealed learning curves that stabilized after the tenth procedure for each surgeon and for each approach. Vascular trauma depended on experience, occurring during the first 10 procedures for each surgeon. Efficacy and operative morbidity were comparable for the two procedures.

CONCLUSION

Endoscopic extraperitoneal lymphadenectomy has a steep learning curve similar to that for transperitoneal laparoscopy.

Laparoscopic infrarenal paraaortic lymph node dissection for restaging of carcinoma of the ovary or fallopian tube

BACKGROUND

The purpose of the study was to investigate the feasibility of laparoscopic paraaortic lymphadenectomy in the restaging of ovarian carcinomas.

METHODS

Nine patients in a referral center seen initially with ovarian (eight patients) or tubal (one patient) carcinoma who had experienced substandard staging during a previous laparotomy or laparoscopy underwent laparoscopic paraaortic lymphadenectomy as part of a surgical staging procedure that included peritoneal fluid sampling and multiple staging biopsies. Omentectomy, appendectomy, pelvic lymphadenectomy, contralateral salpingo-oophorectomy, salpingectomy, or laparoscopically assisted total vaginal hysterectomy was performed during the same operative session when necessary.

RESULTS

All nine lymphadenectomies up to the level of the renal veins were successfully completed. The postoperative periods were uneventful, with an average postoperative stay of 2.8 days.

CONCLUSIONS

Laparoscopic surgery may be an acceptable procedure for paraaortic lymph node sampling, sparing the patient a restaging laparotomy.