Holger Beckmann

Novel antineoplastic agents with efficacy against multidrug resistant tumor cells

A novel series of pentafluorobenzenesulfonamides has been shown to inhibit the growth of a variety of human tumor cell lines. Among the cell types against which these agents were evaluated were the multidrug resistant (MDR) cell lines MCF-7/ADR and P388/ADR. The cytotoxic activity of members of this series of compounds was not affected by the multidrug resistant pump in MCF-7/ADR or P388/ADR cells.

Discovery of INT131: A selective PPARγ modulator that enhances insulin sensitivity

PPARγ is a member of the nuclear hormone receptor family and plays a key role in the regulation of glucose homeostasis. This Letter describes the discovery of a novel chemical class of diarylsulfonamide partial agonists that act as selective PPARγ modulators (SPPARγMs) and display a unique pharmacological profile compared to the thiazolidinedione (TZD) class of PPARγ full agonists. Herein we report the initial discovery of partial agonist 4 and the structure-activity relationship studies that led to the selection of clinical compound INT131 (3), a potent PPARγ partial agonist that displays robust glucose-lowering activity in rodent models of diabetes while exhibiting a reduced side-effects profile compared to marketed TZDs.

Identification of piperazine-bisamide GHSR antagonists for the treatment of obesity

Piperazine-bisamide analogs were discovered as partial agonists of human growth hormone secretagogue receptor (GHSR) in a high throughput screen. The partial agonists were optimized for potency and converted into antagonists through structure-activity relationship (SAR) studies. The efforts also led to the identification of potent antagonist with favorable PK profile suitable as a tool compound for in vivo studies.

Discovery of 1H-Pyrazol-3(2H)-ones as Potent and Selective Inhibitors of Protein Kinase R-like Endoplasmic Reticulum Kinase (PERK).

The structure-based design and optimization of a novel series of selective PERK inhibitors are described resulting in the identification of 44 as a potent, highly selective, and orally active tool compound suitable for PERK pathway biology exploration both in vitro and in vivo.

Unfolded Protein Response in Cancer: IRE1α Inhibition by Selective Kinase Ligands Does Not Impair Tumor Cell Viability.

The kinase/endonuclease inositol requiring enzyme 1 (IRE1α), one of the sensors of unfolded protein accumulation in the endoplasmic reticulum that triggers the unfolded protein response (UPR), has been investigated as an anticancer target. We identified potent allosteric inhibitors of IRE1α endonuclease activity that bound to the kinase site on the enzyme. Structure-activity relationship (SAR) studies led to 16 and 18, which were selective in kinase screens and were potent against recombinant IRE1α endonuclease as well as cellular IRE1α. The first X-ray crystal structure of a kinase inhibitor (16) bound to hIRE1α was obtained. Screening of native tumor cell lines (>300) against selective IRE1α inhibitors failed to demonstrate any effect on cellular viability. These results suggest that IRE1α activity is not essential for viability in most tumor cell lines, in vitro, and that interfering with the survival functions of the UPR may not be an effective strategy to block tumorigenesis.

Novel pyrrolidine melanin-concentrating hormone receptor 1 antagonists with reduced hERG inhibition

We discovered novel pyrrolidine MCHR1 antagonist 1 possessing moderate potency. Profiling of pyrrolidine 1 demonstrated that it was an inhibitor of the hERG channel. Investigation of the structure-activity relationship of this class of pyrrolidines allowed us to optimize the MCHR1 potency and decrease the hERG inhibition. Increasing the acidity of the amide proton by converting the benzamide in lead 1 to an anilide provided single digit nanomolar MCHR1 antagonists while replacing the dimethoxyphenyl ring of 1 with alkyl groups possessing increased polarity dramatically reduced the hERG inhibition.

Differing roles for short chain fatty acids and GPR43 agonism in the regulation of intestinal barrier function and immune responses

Inflammatory bowel disease (IBD) is associated with a loss of intestinal barrier function and dysregulated immune responses. It has been shown that short chain fatty acids (SCFAs) are protective in IBD and that GPR43 mediates the protective effects of SCFAs. In this study, we investigated the effects of SCFAs in comparison to highly specific GPR43 agonists on human intestinal epithelial and immune cells. Our results confirm that SCFAs are enhancers of barrier function in intestinal epithelial cells. Additionally, SCFAs also displayed potent immunoregulatory properties based upon the ability to inhibit LPS-induced cytokine production in PBMC, and human T cell proliferation and cytokine production. Unexpectedly, and in contrast to the current belief, specific GPR43 agonists failed to exhibit similar barrier enhancing and anti-inflammatory properties. These findings demonstrate that SCFA possess broad protective functions in IBD and agonizing GPR43 alone is unlikely to be beneficial in patients.

Abstract 4548: High throughput siRNA screens uncover a high rate of USP8 and ESCRT pathway dependency in squamous carcinoma cell lines

USP8 and the ESCRT pathway (endosomal sorting complex required for transport) are required for cellular homeostasis through key functions in shuttling ubiquitinated proteins towards lysosomal degradation, and through regulating the maturation of autophagosomal structures. In large-scale siRNA screens, the vast majority of cancer cell lines do not demonstrate dependency on USP8 or ESCRT pathway components for viability. However, we identified three cell lines (HCC70, HCC1954 and PFSK1) that are acutely dependent on USP8 and other ESCRT components (HGS, TSG101) for viability. Using a transcriptome-wide association approach, we found that these three USP8-dependent cell lines also had in common the expression of SerpinB3, also known as SCCA1 (Squamous Cell Carcinoma Antigen 1). After selecting additional Squamous Cell Carcinoma cell lines for further validation of USP8-dependency by siRNA screening, we found that Squamous Carcinoma cell lines, irrespective of their SerpinB3 expression status, were far more likely to be dependent on USP8 for viability (23%; N = 22) than cancer cell lines of non-Squamous epithelial origin (4.5%; N = 67). To unravel possible molecular mechanisms underpinning the requirement of USP8 for the viability of USP8-dependent Squamous Carcinoma cell lines (including SCABER, BICR22, CALU1 and EBC1), we conducted additional transcriptome association studies and genetic interaction screens to uncover genes that are synthetic lethal with USP8 knock-down. Citation Format: Wendy Zhong, Elissa Cosgrove, Elissa Swearingen, Mike Ollmann, Jayee Banerjee, Vivienne Watson, Peter Jaeckel, Mariana Pfreimer, Silvia Materna-Reichelt, Holger Beckmann, Paul Kassner, Astrid Ruefli-Brasse, Olivier Nolan-Stevaux. High throughput siRNA screens uncover a high rate of USP8 and ESCRT pathway dependency in squamous carcinoma cell lines. [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 4548.