Optimization of a Screening Hit toward M2912, an Oral Tankyrase Inhibitor with Antitumor Activity in Colorectal Cancer Models

Constitutive activation of the canonical Wnt signaling pathway, in most cases driven by inactivation of the tumor suppressor APC, is a hallmark of colorectal cancer. Tankyrases are druggable key regulators in these malignancies and are considered as attractive targets for therapeutic interventions, although no inhibitor has been progressed to clinical development yet. We continued our efforts to develop tankyrase inhibitors targeting the nicotinamide pocket with suitable drug-like properties for investigating effects of Wnt pathway inhibition on tumor growth. Herein, the identification of a screening hit series and its optimization through scaffold hopping and SAR exploration is described. The systematic assessment delivered M2912, a compound with an optimal balance between excellent TNKS potency, exquisite PARP selectivity, and a predicted human PK compatible with once daily oral dosing. Modulation of cellular Wnt pathway activity and significant tumor growth inhibition was demonstrated with this compound in colorectal xenograft models in vivo.

l-citrulline: A preclinical safety biomarker for the small intestine in rats and dogs in repeat dose toxicity studies

INTRODUCTION

Gastrointestinal (GI) toxicity is still an issue within drug development, especially for novel oncology drugs. The identification of GI mucosal damage at an early stage with high sensitivity and specificity across preclinical species and humans remains difficult. To date, in preclinical studies, no qualified mechanistic, diagnostic or prognostic biomarkers exist for GI mucosal toxicity. l-citrulline is one of the most promising biomarker candidates used in clinical settings to quantify enterocyte integrity in various small intestinal diseases. l-citrulline is an intermediate metabolic amino acid produced mainly by functional enterocytes of the small intestine, whereby enterocyte loss will cause a drop in circulating l-citrulline.

METHODS

In several repeat-dose toxicity studies, plasma l-citrulline has been evaluated as a potential safety biomarker for intestinal toxicity in beagle dogs and Wistar (Han) rats treated with different oncological drug candidates in drug development. Clinical observations and body weight determinations were performed during the pretreatment, treatment and treatment-free recovery period as well as toxicokinetic, gross and histopathology examinations. The quantitative determination of plasma l-citrulline levels during the pretreatment (only dogs), treatment and treatment-free recovery period were performed using an HPLC MS/MS assay. In cynomolgus monkeys, the first investigations on baseline l-citrulline levels were performed.

RESULTS

In dogs, a dose- and exposure-dependent decrease of up to 50% in plasma l-citrulline was seen without histopathological alterations. However, a decrease of more than 50% in comparison to the individual animal pretreatment value of l-citrulline correlated very well with histopathological findings (intestinal crypt necrosis, villus atrophy, enterocyte loss) and clinical signs (bloody faeces and diarrhoea). During a treatment-free recovery period, a trend of increasing levels was observed in dogs. In rats, absolute l-citrulline plasma levels of treated animals decreased compared to the values of the concurrent control group. This decrease also correlated with the histopathological findings in the small intestine (single cell necrosis and mucosa atrophy). Because of a large physiological variation in l-citrulline plasma levels in dogs and rats, a clear cut-off value for absolute l-citrulline levels predictive of intestinal mucosal toxicity was difficult to establish. However, a > 50% decrease in l-citrulline plasma levels during the treatment period strongly correlated with histopathological findings.

DISCUSSION

Based on the performed analysis, a longitudinal investigation of l-citrulline plasma levels for individual animals in the control and treatment groups is essential and pretreatment values of l-citrulline levels in rodents would be highly informative. Overall, further cross-species comparison (Cynomolgus monkey, mouse) and implementation in clinical trials as exploratory biomarker is essential to foster the hypothesis and to understand completely the clinical relevance of l-citrulline as a small intestine biomarker.

Nintedanib in patients with progressive fibrosing interstitial lung diseases-subgroup analyses by interstitial lung disease diagnosis in the INBUILD trial: a randomised, double-blind, placebo-controlled, parallel-group trial

BACKGROUND

The INBUILD trial investigated the efficacy and safety of nintedanib versus placebo in patients with progressive fibrosing interstitial lung diseases (ILDs) other than idiopathic pulmonary fibrosis (IPF). We aimed to establish the effects of nintedanib in subgroups based on ILD diagnosis.

METHODS

The INBUILD trial was a randomised, double-blind, placebo-controlled, parallel group trial done at 153 sites in 15 countries. Participants had an investigator-diagnosed fibrosing ILD other than IPF, with chest imaging features of fibrosis of more than 10% extent on high resolution CT (HRCT), forced vital capacity (FVC) of 45% or more predicted, and diffusing capacity of the lung for carbon monoxide (DLco) of at least 30% and less than 80% predicted. Participants fulfilled protocol-defined criteria for ILD progression in the 24 months before screening, despite management considered appropriate in clinical practice for the individual ILD. Participants were randomly assigned 1:1 by means of a pseudo-random number generator to receive nintedanib 150 mg twice daily or placebo for at least 52 weeks. Participants, investigators, and other personnel involved in the trial and analysis were masked to treatment assignment until after database lock. In this subgroup analysis, we assessed the rate of decline in FVC (mL/year) over 52 weeks in patients who received at least one dose of nintedanib or placebo in five prespecified subgroups based on the ILD diagnoses documented by the investigators: hypersensitivity pneumonitis, autoimmune ILDs, idiopathic non-specific interstitial pneumonia, unclassifiable idiopathic interstitial pneumonia, and other ILDs. The trial has been completed and is registered with ClinicalTrials.gov, number NCT02999178.

FINDINGS

Participants were recruited between Feb 23, 2017, and April 27, 2018. Of 663 participants who received at least one dose of nintedanib or placebo, 173 (26%) had chronic hypersensitivity pneumonitis, 170 (26%) an autoimmune ILD, 125 (19%) idiopathic non-specific interstitial pneumonia, 114 (17%) unclassifiable idiopathic interstitial pneumonia, and 81 (12%) other ILDs. The effect of nintedanib versus placebo on reducing the rate of FVC decline (mL/year) was consistent across the five subgroups by ILD diagnosis in the overall population (hypersensitivity pneumonitis 73·1 [95% CI -8·6 to 154·8]; autoimmune ILDs 104·0 [21·1 to 186·9]; idiopathic non-specific interstitial pneumonia 141·6 [46·0 to 237·2]; unclassifiable idiopathic interstitial pneumonia 68·3 [-31·4 to 168·1]; and other ILDs 197·1 [77·6 to 316·7]; p=0·41 for treatment by subgroup by time interaction). Adverse events reported in the subgroups were consistent with those reported in the overall population.

INTERPRETATION

The INBUILD trial was not designed or powered to provide evidence for a benefit of nintedanib in specific diagnostic subgroups. However, its results suggest that nintedanib reduces the rate of ILD progression, as measured by FVC decline, in patients who have a chronic fibrosing ILD and progressive phenotype, irrespective of the underlying ILD diagnosis.

FUNDING

Boehringer Ingelheim.

Chronic Lung Allograft Dysfunction: Evolving Concepts and Therapies

Lung transplantation has become an established therapeutic option for a variety of end-stage lung diseases. Technical advances in graft procurement, implantation, perioperative care, immunosuppression, and posttransplant medical management have led to significant improvements in 1-year survival, but outcomes after the first year have improved minimally over the last two decades. The main limitation to better long-term survival after lung transplantation is chronic lung allograft dysfunction (CLAD). CLAD also impairs quality of life and increases the costs of medical care. Our understanding of CLAD manifestations, risk factors, and mechanisms is rapidly evolving. Recognition of different CLAD phenotypes (e.g., bronchiolitis obliterans syndrome and restrictive allograft syndrome) and the unique pathogenic mechanisms will be important for developing novel therapies. In addition to alloimmune-mediated rejection, we now recognize the importance of alloimmune-independent mechanisms of injury to the allograft. CLAD is the consequence of dysregulated repair of allograft injury. Unfortunately, currently available therapies for CLAD are usually not effective. However, the advances in knowledge, reviewed in this manuscript, should lead to novel strategies for CLAD prevention and treatment, as well as improvement in long-term outcomes after lung transplantation. We provide an overview of the evolving terminology related to CLAD, its varying clinical phenotypes and their diagnosis, natural history, pathogenesis, and potential treatments.

Assessing the mechanism and therapeutic potential of modulators of the human Mediator complex-associated protein kinases

Mediator-associated kinases CDK8/19 are context-dependent drivers or suppressors of tumorigenesis. Their inhibition is predicted to have pleiotropic effects, but it is unclear whether this will impact on the clinical utility of CDK8/19 inhibitors. We discovered two series of potent chemical probes with high selectivity for CDK8/19. Despite pharmacodynamic evidence for robust on-target activity, the compounds exhibited modest, though significant, efficacy against human tumor lines and patient-derived xenografts. Altered gene expression was consistent with CDK8/19 inhibition, including profiles associated with super-enhancers, immune and inflammatory responses and stem cell function. In a mouse model expressing oncogenic beta-catenin, treatment shifted cells within hyperplastic intestinal crypts from a stem cell to a transit amplifying phenotype. In two species, neither probe was tolerated at therapeutically-relevant exposures. The complex nature of the toxicity observed with two structurally-differentiated chemical series is consistent with on-target effects posing significant challenges to the clinical development of CDK8/19 inhibitors.

Developmental effects of coumarin and the anticoagulant coumarin derivative warfarin on zebrafish (Danio rerio) embryos

Coumarin and warfarin, two substances which are intensively metabolized in animals and humans, were tested for teratogenicity and embryo lethality in a 3-day in vitro assay using zebrafish embryos. Warfarin is a coumarin derivative, but in contrast to the mother substance warfarin has anticoagulant properties. Both substances produced teratogenic and lethal effects in zebrafish embryos. The LC(50) and EC(50) values for coumarin are 855 μM and 314 μM, respectively; the corresponding values for warfarin are 988 μM and 194 μM. For coumarin, three main or fingerprint endpoints (malformation of head, tail and growth retardation) were identified, whereas malformation of tail was the only fingerprint endpoint of warfarin. The analysis of the ratios between the zebrafish embryo effect concentrations of both substances and human therapeutic plasma concentrations confirmed the teratogenic potential of warfarin, as well as the equivocal status of coumarin.