Diffusion-weighted imaging complements T2-weighted MRI for tumour response assessment in squamous anal carcinoma.

OBJECTIVES: A published tumour regression grade (TRG) score for squamous anal carcinoma treated with definitive chemoradiotherapy based on T2-weighted MRI yields a high proportion of indeterminate responses (TRG-3). We investigate whether the addition of diffusion-weighted imaging (DWI) improves tumour response assessment in the early post treatment period. MATERIALS AND METHODS: This retrospective observational study included squamous anal carcinoma patients undergoing MRI before and within 3 months of completing chemoradiotherapy from 2009 to 2020. Four independent radiologists (1-20 years' experience) scored MRI studies using a 5-point TRG system (1 = complete response; 5 = no response) based on T2-weighted sequences alone, and then after a 12-week washout period, using a 5-point DWI-TRG system based on T2-weighted and DWI. Scoring confidence was recorded on a 5-point scale (1 = low; 5 = high) for each reading and compared using the Wilcoxon test. Indeterminate scores (TRG-3) from each reading session were compared using the McNemar test. Interobserver agreement was assessed using kappa statistics. RESULTS: Eighty-five patients were included (mean age, 59 years ± 12 [SD]; 55 women). T2-weighted TRG-3 scores from all readers combined halved from 24% (82/340) to 12% (41/340) with DWI (p < 0.001). TRG-3 scores changed most frequently (41%, 34/82) to DWI-TRG-2 (excellent response). Complete tumour response was recorded clinically in 77/85 patients (91%). Scoring confidence increased using DWI (p < 0.001), with scores of 4 or 5 in 84% (287/340). Interobserver agreement remained fair to moderate (kappa range, 0.28-0.58). CONCLUSION: DWI complements T2-weighted MRI by reducing the number of indeterminate tumour responses (TRG-3). DWI increases radiologist's scoring confidence. CLINICAL RELEVANCE STATEMENT: Diffusion-weighted imaging improves T2-weighted tumour response assessment in squamous anal cancer, halving the number of indeterminate responses in the early post treatment period, and increases radiologists' confidence. KEY POINTS: Tumour response based on T2-weighted MRI is often indeterminate in squamous anal carcinoma. Diffusion-weighted imaging alongside T2-weighted MRI halved indeterminate tumour regression grade scores assigned by four radiologists from 24 to 12%. Scoring confidence of expert and non-expert radiologists increased with the inclusion of diffusion-weighted imaging.

Determination of absolute configuration and binding efficacy of benzimidazole-based FabI inhibitors through the support of electronic circular dichroism and MM-GBSA techniques.

We have previously reported benzimidazole-based compounds to be potent inhibitors of FabI for Francisella tularensis (FtFabI), making them promising antimicrobial hits. Optically active enantiomers exhibit markedly differing affinities toward FtFabI. The IC50 of benzimidazole (-)-1 is ∼100× lower than the (+)-enantiomer, with similar results for the 2 enantiomers. Determining the absolute configuration for these optical compounds and elucidating their binding modes is important for further design. Electronic circular dichroism (ECD) quantum calculations have become important in determining absolute configurations of optical compounds. We determined the absolute configuration of (-)/(+)-1 and (-)/(+)-2 by comparing experimental spectra and theoretical density functional theory (DFT) simulations of ECD spectra at the B3LYP/6-311+G(2d, p) level using Gaussian09. Comparison of experimental and calculated ECD spectra indicates that the S configuration corresponds to the (-)-rotation for both compounds 1 and 2, while the R configuration corresponds to the (+)-rotation. Further, molecular dynamics simulations and MM-GBSA binding energy calculations for these two pairs of enantiomers with FtFabI show much tighter binding MM-GBSA free energies for S-1 and S-2 than for their enantiomers, R-1 and R-2, consistent with the S configuration being the more active one, and with the ECD determination of the S configuration corresponding to (-) and the R configuration corresponding to (+). Thus, our computational studies allow us to assign (-) to (S)- and (+) to (R)- for compounds 1 and 2, and to further evaluate structural changes to improve efficacy.

A novel series of enoyl reductase inhibitors targeting the ESKAPE pathogens, Staphylococcus aureus and Acinetobacter baumannii.

S. aureus and A. baumannii are among the ESKAPE pathogens that are increasingly difficult to treat due to the rise in the number of drug resistant strains. Novel therapeutics targeting these pathogens are much needed. The bacterial enoyl reductase (FabI) is as potentially significant drug target for developing pathogen-specific antibiotics due to the presence of alternate FabI isoforms in many other bacterial species. We report the identification and development of a novel N-carboxy pyrrolidine scaffold targeting FabI in S. aureus and A. baumannii, two pathogens for which FabI essentiality has been established. This scaffold is unrelated to other known antibiotic families, and FabI is not targeted by any currently approved antibiotic. Our data shows that this scaffold displays promising enzyme inhibitory activity against FabI from both S. aureus and A. baumannii, as well as encouraging antibacterial activity in S. aureus. Compounds also display excellent synergy when combined with colistin and tested against A. baumannii. In this combination the MIC of colistin is reduced by 10-fold. Our first generation compound displays promising enzyme inhibition, targets FabI in S. aureus with a favorable selectivity index (ratio of cytotoxicity to MIC), and has excellent synergy with colistin against A. baumannii, including a multidrug resistant strain.

Structural and biological evaluation of a novel series of benzimidazole inhibitors of Francisella tularensis enoyl-ACP reductase (FabI).

Francisella tularensis, the causative agent of tularemia, presents a significant biological threat and is a Category A priority pathogen due to its potential for weaponization. The bacterial FASII pathway is a viable target for the development of novel antibacterial agents treating Gram-negative infections. Here we report the advancement of a promising series of benzimidazole FabI (enoyl-ACP reductase) inhibitors to a second-generation using a systematic, structure-guided lead optimization strategy, and the determination of several co-crystal structures that confirm the binding mode of designed inhibitors. These compounds display an improved low nanomolar enzymatic activity as well as promising low microgram/mL antibacterial activity against both F. tularensis and Staphylococcus aureus and its methicillin-resistant strain (MRSA). The improvements in activity accompanying structural modifications lead to a better understanding of the relationship between the chemical structure and biological activity that encompasses both enzymatic and whole-cell activity.

An Engineered IL15 Cytokine Mutein Fused to an Anti-PD1 Improves Intratumoral T-cell Function and Antitumor Immunity.

The use of cytokines for immunotherapy shows clinical efficacy but is frequently accompanied by severe adverse events caused by excessive and systemic immune activation. Here, we set out to address these challenges by engineering a fusion protein of a single, potency-reduced, IL15 mutein and a PD1-specific antibody (anti-PD1-IL15m). This immunocytokine was designed to deliver PD1-mediated, avidity-driven IL2/15 receptor stimulation to PD1+ tumor-infiltrating lymphocytes (TIL) while minimally affecting circulating peripheral natural killer (NK) cells and T cells. Treatment of tumor-bearing mice with a mouse cross-reactive fusion, anti-mPD1-IL15m, demonstrated potent antitumor efficacy without exacerbating body weight loss in B16 and MC38 syngeneic tumor models. Moreover, anti-mPD1-IL15m was more efficacious than an IL15 superagonist, an anti-mPD-1, or the combination thereof in the B16 melanoma model. Mechanistically, anti-PD1-IL15m preferentially targeted CD8+ TILs and single-cell RNA-sequencing analyses revealed that anti-mPD1-IL15m treatment induced the expansion of an exhausted CD8+ TIL cluster with high proliferative capacity and effector-like signatures. Antitumor efficacy of anti-mPD1-IL15m was dependent on CD8+ T cells, as depletion of CD8+ cells resulted in the loss of antitumor activity, whereas depletion of NK cells had little impact on efficacy. The impact of anti-hPD1-IL15m on primary human TILs from patients with cancer was also evaluated. Anti-hPD1-IL15m robustly enhanced the proliferation, activation, and cytotoxicity of CD8+ and CD4+ TILs from human primary cancers in vitro, whereas tumor-derived regulatory T cells were largely unaffected. Taken together, our findings showed that anti-PD1-IL15m exhibits a high translational promise with improved efficacy and safety of IL15 for cancer immunotherapy via targeting PD1+ TILs.See related Spotlight by Felices and Miller, p. 1110.

Ligand-Blocking and Membrane-Proximal Domain Targeting Anti-OX40 Antibodies Mediate Potent T Cell-Stimulatory and Anti-Tumor Activity.

Agonistic antibodies targeting the tumor necrosis factor (TNF) superfamily of co-stimulatory receptors (TNFRSF) are progressing through various stages of clinical development for cancer treatment, but the desired and defining features of these agents for optimal biological activity remain controversial. One idea, based on recent studies with CD40, is that non-ligand-blocking antibodies targeting membrane-distal cysteine-rich domain 1 (CRD1) have superior agonistic activities compared with ligand-blocking antibodies targeting more membrane-proximal CRDs. Here, we determined the binding and functional characteristics of a panel of antibodies targeting CRDs 1-4 of OX40 (also known as TNFRSF4 or CD134). In striking contrast to CD40, we found that ligand-blocking CRD2-binding and membrane-proximal CRD4-binding anti-OX40 antibodies have the strongest agonistic and anti-tumor activities. These findings have important translational implications and further highlight that the relationship between epitope specificity and agonistic activity will be an important issue to resolve on a case-by-case basis when optimizing antibodies targeting different co-stimulatory tumor necrosis factor receptors (TNFRs).

Author Correction: Targeting CLDN18.2 by CD3 Bispecific and ADC Modalities for the Treatments of Gastric and Pancreatic Cancer.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Targeting CLDN18.2 by CD3 Bispecific and ADC Modalities for the Treatments of Gastric and Pancreatic Cancer.

Human CLDN18.2 is highly expressed in a significant proportion of gastric and pancreatic adenocarcinomas, while normal tissue expression is limited to the epithelium of the stomach. The restricted expression makes it a potential drug target for the treatment of gastric and pancreatic adenocarcinoma, as evidenced by efforts to target CLDN18.2 via naked antibody and CAR-T modalities. Herein we describe CLDN18.2-targeting via a CD3-bispecific and an antibody drug conjugate and the characterization of these potential therapeutic molecules in efficacy and preliminary toxicity studies. Anti-hCLDN18.2 ADC, CD3-bispecific and diabody, targeting a protein sequence conserved in rat, mouse and monkey, exhibited in vitro cytotoxicity in BxPC3/hCLDN18.2 (IC50 = 1.52, 2.03, and 0.86 nM) and KATO-III/hCLDN18.2 (IC50 = 1.60, 0.71, and 0.07 nM) respectively and inhibited tumor growth of pancreatic and gastric patient-derived xenograft tumors. In a rat exploratory toxicity study, the ADC was tolerated up to 10 mg/kg. In a preliminary assessment of tolerability, the anti-CLDN18.2 diabody (0.34 mg/kg) did not produce obvious signs of toxicity in the stomach of NSG mice 4 weeks after dosing. Taken together, our data indicate that targeting CLDN18.2 with an ADC or bispecific modality could be a valid therapeutic approach for the treatment of gastric and pancreatic cancer.

Leptin and adiponectin interact in the regulation of prostate cancer cell growth via modulation of p53 and bcl-2 expression.

OBJECTIVE: To investigate the effects of leptin, full-length adiponectin (fAd) and globular adiponectin (gAd), alone and in combination, on LNCaP and PC3 prostate cancer cell proliferation, and on the expression of p53 and bcl-2 gene expression. MATERIALS AND METHODS: LNCaP and PC3 prostate cancer cells were cultured and treated with the following: 0-100 nM leptin; 0-100 nM fAd +/- 100 nM leptin; 0-100 nM gAd +/- 100 nM leptin. Proliferation assays and quantitative reverse transcriptase-polymerase chain reaction for p53 tumour-suppressor gene and bcl-2 oncogene expression were performed on treated samples. RESULTS: Co-incubation of PC3 cells with 100 nM leptin and 1 or 100 nM fAd significantly decreased cell proliferation to approximately half of basal (P < 0.001); there was no significant effect in LNCaP cells. Leptin-induced inhibition of p53 expression in LNCaP cells was rescued by fAd. Leptin and fAd dose-dependently potentiated p53 expression in PC3 cells (P < 0.001); leptin and gAd also increased p53 expression (P < 0.05 and P < 0.001). fAd and gAd had no effect on bcl-2 expression in the presence of leptin in LNCaP cells. In PC3 cells, bcl-2 expression was inhibited to negligible levels in the presence of leptin. CONCLUSIONS: Leptin and adiponectin interact, resulting in the inhibition of prostate cancer cell proliferation, particularly in PC3 cells, via modulation of p53 and bcl-2 expression. Our findings support the notion that high leptin and low adiponectin levels may be important in driving obesity-related prostate cancer progression.

A 10-year retrospective audit of penile cancer management in the UK.

OBJECTIVE: To audit the penile cancer workload, management and outcome within a regional cancer network serving a population of approximately 1 million in the West Midlands (UK), comparing these data to that published by the British Association of Urological Surgeons National Cancer Registry, the UK National Institute of Clinical Excellence and the European Associations of Urology guidelines. PATIENTS AND METHODS: Patients diagnosed with or treated for penile cancer within the Arden Cancer Network over a 10-year period were identified retrospectively, and data relating to histology, local treatment, lymph node management, outcome and survival were recorded. RESULTS: Data were obtained for 65 patients; 61 (94%) had histologically confirmed squamous cell carcinoma (SCC) of the penis, equating to approximately 0.6 cases per 100 000 population per year. Their mean age at diagnosis was 63 years. Of SCCs, 86% were located on the glans and/or foreskin. Thirty-six patients had conservative primary local therapy, mostly for T0 or T1 disease. The 5-year relapse-free survival after radiotherapy was 63%, although survival after salvage penectomy was 75% at 4 years. Forty-seven patients had lymph node surveillance; 11 developed lymph node disease and had lymph node dissection (LND) with or with no radiotherapy, but survival was poor. Primary inguinal LND with or without radiotherapy was used in eight patients, and was associated with a good survival, although three were found to have negative histology after LND. Survival was strongly influenced by T and N stage at presentation and the 5-year survival for the whole group was 71%. CONCLUSION: The workload, incidence and overall mortality from penile cancer within the Arden Cancer Network are in line with those in the rest of the UK. Rates of conservative therapy were good in this group and associated with good survival. Survival could be improved by identifying and aggressively treating those patients at high risk of lymph node disease.

Benzimidazole-Based FabI Inhibitors: A Promising Novel Scaffold for Anti-staphylococcal Drug Development.

The enoyl-ACP reductase (FabI) enzyme is a well validated target for anti-staphylococcal drug discovery and development. With the goal of finding alternate therapeutics for drug-resistant strains of Staphylococcus aureus, such as methicillin-resistant S. aureus (MRSA), our previously published series of benzimidazole-based inhibitors of the FabI enzyme from Francisella tularensis (FtFabI) have been evaluated against FabI from S. aureus (SaFabI). We report here the preliminary structure-activity relationship of this series and the prioritization of compounds toward lead optimization. Mutational studies have identified key residues that contribute toward stabilizing the inhibitors in the active site of FabI. Mutations that do not significantly impact enzyme function but destabilize inhibitor binding are more likely to occur in nature as organisms evolve to evade the action of antibiotics leading to resistance. Identifying these residues provides guidance for minimizing susceptibility to resistance. Additionally, we have identified compounds that elicit antibacterial activity through off-target effects and observe that close analogs can display differing modes of action (on-target vs off-target) and need to be individually evaluated early on to prioritize compounds for lead optimization. Overall, our data suggest that the benzimidazole scaffold is a promising scaffold for anti-staphylococcal drug development.

A novel role for the adipokine visfatin/pre-B cell colony-enhancing factor 1 in prostate carcinogenesis.

Adipose tissue is now well established as an endocrine organ and multiple hormones termed 'adipokines' are released from it. With the rapidly increasing obese population and the increased risk mortality from prostate cancer within the obese population we looked to investigate the role of the adipokine visfatin in LNCaP and PC3 prostate cancer cell lines. Using immunohistochemistry and immunocytochemistry we demonstrate visfatin expression in LNCaP (androgen-sensitive) and PC3 (androgen-insensitive) human prostate cancer cell lines as well as human prostate cancer tissue. Additionally, we show that visfatin increases PC3 cell proliferation and demonstrate the activation of the MAPKs ERK-1/2 and p38. Moreover we also demonstrate that visfatin promotes the expression and activity of MMP-2/9 which are important proteases involved in the breakdown of the extracellular matrix, suggesting a possible role for visfatin in prostate cancer metastases. These data suggest a contributory and multifunctional role for visfatin in prostate cancer progression, with particular relevance and emphasis in an obese population.

Obesity and prostate cancer: a role for adipokines.

OBJECTIVES: Many studies have investigated the association between obesity and prostate cancer risk but have yielded inconsistent results. Recent evidence suggests a particular role for obesity in prostate cancer progression. Many studies have investigated the roles of adipose tissue-derived factors (adipokines) as putative molecular mediators between obesity and prostate cancer. This review provides an overview of current evidence that supports such a role for adipokines. METHODS: A comprehensive literature review was carried out using PubMed to search for articles relating to prostate cancer and the following adipokines: leptin, interleukin 6, vascular endothelial growth factor (VEGF), and adiponectin. RESULTS: Prostate cancer cells are exposed to adipokines either via the circulation or through locally produced adipokines following invasion of the retropubic fat pad. Circulating levels of most adipokines are positively correlated with obesity; adiponectin is inversely correlated with obesity. High circulating levels of leptin, interleukin 6, and VEGF are associated with increased prostate cancer risk and increased aggressiveness. Adiponectin levels are lower in patients with prostate cancer and are inversely associated with grade of disease. Adipokines exert a variety of biologic effects on prostate cancer cells, modulating cellular differentiation, apoptosis, proliferation, and angiogenesis. CONCLUSIONS: Evidence suggests a role for obesity and adipokines in promoting the progression of established prostate cancer. Adipokines may contribute to the molecular basis for the association between obesity and prostate cancer, but the complex pathophysiology of both these disease states requires further studies.