Design and biological characterization of a series of dual mechanism ERK1/2 inhibitors with a Triazolopyridinone core

Oncology clinical development programs have targeted the RAS/RAF/MEK/ERK signaling pathway with small molecule inhibitors for a variety of cancers during the past decades, and most therapies have shown limited or minimal success. Specific BRAF and MEK inhibitors have shown clinical efficacy in patients for the treatment of BRAF-mutant melanoma. However, most cancers have shown treatment resistance after several months of inhibitor usage, and reports indicate resistance is often associated with the reactivation of the MAPK signaling pathway. It is widely accepted that an effective MAPK therapy will have a significant impact on curtailing cancer growth and improving patient survival. However, despite more than three decades of intense research and pharmaceutical industry efforts, an FDA-approved, effective anti-cancer ERK inhibitor has yet to be developed. Here, we present the design, optimization, and biological characterization of ERK1/2 inhibitors that block catalytic phosphorylation of downstream substrates such as RSK but also modulate the phosphorylation of ERK1/2 by MEK without directly inhibiting MEK. Our series of dual mechanism ERK1/2 inhibitors, in which we incorporated a triazolopyridinone core, may present potential benefits for enhancing efficacy and addressing the emergence of treatment resistance.

When Global Becomes Virtual: A Survey of Virtual Global Health Education Activities During the COVID-19 Pandemic Among Pediatric Educators

BACKGROUND

During the COVID-19 pandemic, global health education activities were disrupted. Transitioning to virtual options has allowed educators and trainees to continue global health education and partnerships, though the acceptability and implementation of this transition is unknown.

OBJECTIVE

To evaluate current and planned virtual global health education activities (VGHEAs) of a group of US global health educators during the COVID-19 pandemic and to assess perceived benefits and challenges of VGHEAs.

METHODS

A cross-sectional study of pediatric faculty and trainees involved in global health education from 8 institutions in the United States were surveyed anonymously about their global health education activities in 2021. Authors used representative convenience sampling and invited at least 1 faculty member and 2 trainees from each institution in the Midwest Consortium of Global Child Health Educators.

RESULTS

All 8 institutions responded to the survey, with 38 faculty and trainee participants. Institutional implementation of virtual education activities was variable. Respondents reported that VGHEAs allowed them to maintain partnerships with low-middle income countries, though they noted that unreliable internet connections presented challenges. One program reported funding cuts to its global health program during the pandemic.

CONCLUSIONS

The COVID-19 pandemic created challenges for global health education programs. Educators and trainees are interested in using potentially cost-saving VGHEAs to maintain international collaborations, continue global health education efforts, and even increase access to equitable educational activities despite pandemic disruptions.

Investigating transmission of SARS-CoV-2 using novel face mask sampling: a protocol for an observational prospective study of index cases and their contacts in a congregate setting

INTRODUCTION

This study aims to measure how transmission of SARS-CoV-2 occurs in communities and to identify conditions that lend to increased transmission focusing on congregate situations. We will measure SARS-CoV-2 in exhaled breath of asymptomatic and symptomatic persons using face mask sampling-a non-invasive method for SARS-CoV-2 detection in exhaled air. We aim to detect transmission clusters and identify risk factors for SARS-CoV-2 transmission in presymptomatic, asymptomatic and symptomatic individuals.

METHODS AND ANALYSIS

In this observational prospective study with daily follow-up, index cases and their respective contacts are identified at each participating institution. Contact definitions are based on Centers for Disease Control and Prevention and local health department guidelines. Participants will wear masks with polyvinyl alcohol test strips adhered to the inside for 2 hours daily. The strips are applied to all masks used over at least 7 days. In addition, self-administered nasal swabs and (optional) finger prick blood samples are performed by participants. Samples are tested by standard PCR protocols and by novel antigen tests.

ETHICS AND DISSEMINATION

This study was approved by the Colorado Multiple Institutional Review Board and the WHO Ethics Review Committee. From the data generated, we will analyse transmission clusters and risk factors for transmission of SARS-CoV-2 in congregate settings. The kinetics of asymptomatic transmission and the evaluation of non-invasive tools for detection of transmissibility are of crucial importance for the development of more targeted control interventions-and ultimately to assist with keeping congregate settings open that are essential for our social fabric.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov (#NCT05145803).

Detection of SARS-CoV-2 in exhaled air using non-invasive embedded strips in masks

Background

SARS-CoV-2 emerged in 2019 and resulted in a pandemic causing millions of infections worldwide. Gold-standard for SARS-CoV-2 detection uses quantitative RT-qPCR on respiratory secretions to detect viral RNA (vRNA). Acquiring these samples is invasive, can be painful for those with xerostomia and other health conditions, and sample quality can vary greatly. Frequently only symptomatic individuals are tested even though asymptomatic individuals can have comparable viral loads and efficiently transmit virus.

Methods

We utilized a non-invasive approach to detect SARS-CoV-2 in individuals, using polyvinyl alcohol (PVA) strips embedded in KN95 masks. PVA strips were tested for SARS-CoV-2 vRNA via qRT-PCR and infectious virus.

Results

We show efficient recovery of vRNA and infectious virus from virus-spiked PVA with detection limits comparable to nasal swab samples. In infected individuals, we detect both human and SARS-CoV-2 RNA on PVA strips, however, these levels are not correlated with length of time mask was worn, number of times coughed or sneezed, or level of virus in nasal swab samples. We successfully cultured and deep-sequenced PVA-associated virus.

Conclusions

These results demonstrate the feasibility of using PVA-embedded masks as a non-invasive platform for detecting SARS-CoV-2 in exhaled air in COVID-positive individuals regardless of symptom status.

Abstract 2643: Design and discovery of novel oral INV-88 macrophage migration inhibitory factor (MIF) inhibitors: Potent anti-tumor activity in vitro and in vivo

Background: MIF is a pleiotropic cytokine critically implicated in tumorigenesis. Tumor cell- and immune effector cell-derived MIF are localized to exosomal, extracellular, cytoplasmic and intranuclear compartments. MIF activates MAPK and PI3K signal transduction, inhibits apoptosis, promotes angiogenesis, elicits premetastatic niche formation and resolves DNA replication stress; contributing to unperturbed cancer cell growth and metastasis. MIF overexpression in several cancers is a negative prognostic indicator associated with poor overall patient survival.

Methods & Results: Active novel INV-88 MIF inhibitors were discovered using structure-based drug design against critical MIF pharmacophoric binding sites guided by high-resolution X-ray crystallography (Brookhaven) of INV-88 compound:hu-MIF protein bound complexes. Following an iterative medicinal chemistry campaign; stringent biochemical, pharmacological and ADMET funnel screening identified promising INV-88 lead candidates with potent antitumor activities. Strong MIF binding by INV-88 compounds was demonstrated using thermal shift and fluorescence polarization assays. Profound in vitro antitumor pharmacological properties of INV-88 were established on several murine & human tumor cell lines (HCT116, MeWo, DU145, 4T1, B16-F10, CT26). INV-88 inhibitors demonstrated potent anti-proliferative effects down to nM IC50 potencies and impeded 3D spheroid growth & viability. Disruption of MIF:CD74/CD44-mediated MAPK and PI3K signal transduction pathways by INV-88 compounds blocked ERK and AKT phosphorylation leading to decreased pERK1/2 and pAKT levels. INV-88 inhibitors increased Caspase-3/7, p53 and Bax but decreased Bcl-2 levels. INV-88 lead compounds inhibited tumor MIF protein production in 2D & 3D cell culture systems with concomitant pan-inhibition of tumorigenic proinflammatory cytokine (TNF-α, IL-1β, IL-6, and IL-8) expression by stromal cells. Optimal ADMET properties of INV-88 compounds enabled oral dosing of select INV-88 clinical candidate compounds in mouse syngeneic B16-F10 melanoma and CT26 colon carcinoma models. Mice were dosed daily with INV-88 or vehicle per oral gavage starting in BALB/c and in C57/BL6 mice upon demonstrating palpable tumors after s.c. implantation of CT26 and B16-F10 tumor cells, respectively. Tumor growth inhibition was observed with rates of 71% on Day 24 (CT26) and 75% on Day 20 (B16-F10). INV-88 treatment significantly inhibited CT26 [p<0.0001] and B16-F10 tumor growth [p<0.0001] versus controls. INV-88 was well-tolerated by tumor-bearing mice which exhibited normal body condition scores and body weight.

Conclusion: The data presented highlight the potential therapeutic utility of pharmacological MIF inhibition with oral INV-88 new chemical entities as a novel immunotherapeutic treatment modality for cancer.

Citation Format: Anderson Gaweco, Vincent Chung, Jefferson Tilley, William Windsor, Terry Stouch, John Ellingboe, Gregg Crichlow, Philipp Sabanas, Christian Sebesta. Design and discovery of novel oral INV-88 macrophage migration inhibitory factor (MIF) inhibitors: Potent anti-tumor activity in vitro and in vivo [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 2643.

Perceived roles, benefits and barriers of virtual global health partnership initiatives: a cross-sectional exploratory study

Background

Virtual global health partnership initiatives (VGHPIs) evolved rapidly during the COVID-19 pandemic to ensure partnership continuity. However the current landscape for VGHPI use and preference is unknown. This study aimed to increase understanding of GH partners’ perspectives on VGHPIs.

Methods

From 15 October to 30 November 2020, An online, international survey was conducted using snowball sampling to document pandemic-related changes in partnership activities, preferences for VGHPIs, and perceived acceptability and barriers. The survey underwent iterative development within a diverse author group, representing academic and clinical institutions, and the non-profit sector. Participants from their professional global health networks were invited, including focal points for global health partnerships while excluding trainees and respondents from the European Economic Area. Analysis stratified responses by country income classification and partnership type. Authors used descriptive statistics to characterize responses, defining statistical significance as α = 0.05.

Results

A total of 128 respondents described 219 partnerships. 152/219 (69%) partnerships were transnational, 157/219 (72%) were of > 5 years duration, and 127/219 (60%) included bidirectional site visits. High-income country (HIC) partners sent significantly more learners to low- to middle-income country (LMIC) partner sites (p < 0.01). Participants commented on pandemic-related disruptions affecting 217/219 (99%) partnerships; 195/217 (90%) were disruption to activities; 122/217 (56%) to communication; 73/217 (34%) to access to professional support; and 72/217 (33%) to funding. Respondents indicated that VGHPIs would be important to 206/219 (94%) of their partnerships moving forward. There were overall differences in resource availability, technological capacity, and VGHPI preferences between LMIC and HIC respondents, with a statistically significant difference in VGHPI acceptability (p < 0.001). There was no significant difference between groups regarding VGHPIs’ perceived barriers.

Conclusions

The pandemic disrupted essential partnership elements, compounding differences between LMIC and HIC partners in their resources and preferences for partnership activities. VGHPIs have the potential to bridge new and existing gaps and maximize gains, bi-directionality, and equity in partnerships during and after COVID-19.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41256-022-00244-4.

Regulation of Lipoprotein Homeostasis by Self-Assembling Peptides

High levels of serum low-density lipoprotein (LDL) cholesterol contribute to atherosclerosis, a key risk factor of cardiovascular diseases. PCSK9 is a circulatory enzyme that downregulates expression of hepatic LDL receptors, concomitantly increasing serum LDL-C. This work investigates a small, self-assembling peptide, EPep2-8, as a peptide inhibitor of PCSK9. EPep2-8 is a multidomain peptide comprising a self-assembling domain, E2, conjugated to a bioactive domain, Pep2-8, previously shown to inhibit PCSK9. The E2 domain facilitates self-assembly of EPep2-8 into long, nanofibrous polymers with an underlying supramolecular β-sheet secondary structure. Intermolecular interactions between nanofibers drive EPep2-8 to form a thixotropic and cytocompatible hydrogel in aqueous and charge-neutral solutions. These properties enable EPep2-8 to be delivered as an in situ depot for regulation of lipoprotein homeostasis. In surface plasmon resonance studies, EPep2-8 bound specifically to PCSK9 with an apparent, noncovalent, and irreversible dissociation, significantly improving the binding affinity of Pep2-8 alone (KD = 667 ± 48 nM). Increased binding affinity of EPep2-8 is primarily due to the superstoichiometric interaction of the peptide with PCSK9. Promisingly, EPep2-8 retains bioactivity in vitro, engendering dose-dependent uptake of LDL-C in hepatocytes. This mechanism of self-assembly on a target site may be a simple method to improve the affinity of peptide inhibitors.

Discovery of 3(S)-thiomethyl pyrrolidine ERK inhibitors for oncology

Compound 5 (SCH772984) was identified as a potent inhibitor of ERK1/2 with excellent selectivity against a panel of kinases (0/231 kinases tested @ 100 nM) and good cell proliferation activity, but suffered from poor PK (rat AUC PK @10 mpk = 0 μM h; F% = 0) which precluded further development. In an effort to identify novel ERK inhibitors with improved PK properties with respect to 5, a systematic exploration of sterics and composition at the 3-position of the pyrrolidine led to the discovery of a novel 3(S)-thiomethyl pyrrolidine analog 28 with vastly improved PK (rat AUC PK @10 mpk = 26 μM h; F% = 70).

Discovery of a novel ERK inhibitor with activity in models of acquired resistance to BRAF and MEK inhibitors

The high frequency of activating RAS or BRAF mutations in cancer provides strong rationale for targeting the mitogen-activated protein kinase (MAPK) pathway. Selective BRAF and MAP-ERK kinase (MEK) inhibitors have shown clinical efficacy in patients with melanoma. However, the majority of responses are transient, and resistance is often associated with pathway reactivation of the extracellular signal-regulated kinase (ERK) signaling pathway. Here, we describe the identification and characterization of SCH772984, a novel and selective inhibitor of ERK1/2 that displays behaviors of both type I and type II kinase inhibitors. SCH772984 has nanomolar cellular potency in tumor cells with mutations in BRAF, NRAS, or KRAS and induces tumor regressions in xenograft models at tolerated doses. Importantly, SCH772984 effectively inhibited MAPK signaling and cell proliferation in BRAF or MEK inhibitor-resistant models as well as in tumor cells resistant to concurrent treatment with BRAF and MEK inhibitors. These data support the clinical development of ERK inhibitors for tumors refractory to MAPK inhibitors.

Dinaciclib (SCH 727965), a novel and potent cyclin-dependent kinase inhibitor

Cyclin-dependent kinases (CDK) are key positive regulators of cell cycle progression and attractive targets in oncology. SCH 727965 inhibits CDK2, CDK5, CDK1, and CDK9 activity in vitro with IC(50) values of 1, 1, 3, and 4 nmol/L, respectively. SCH 727965 was selected as a clinical candidate using a functional screen in vivo that integrated both efficacy and safety parameters. Compared with flavopiridol, SCH 727965 exhibits superior activity with an improved therapeutic index. In cell-based assays, SCH 727965 completely suppressed retinoblastoma phosphorylation, which correlated with apoptosis onset and total inhibition of bromodeoxyuridine incorporation in >100 tumor cell lines of diverse origin and background. Moreover, short exposures to SCH 727965 were sufficient for long-lasting cellular effects. SCH 727965 induced regression of established solid tumors in a range of mouse models following intermittent scheduling of doses below the maximally tolerated level. This was associated with modulation of pharmacodynamic biomarkers in skin punch biopsies and rapidly reversible, mechanism-based effects on hematologic parameters. These results suggest that SCH 727965 is a potent and selective CDK inhibitor and a novel cytotoxic agent.

Fluorescence polarization assay and inhibitor design for MDM2/p53 interaction

MDM2 is an important negative regulator of the tumor suppressor protein p53 which regulates the expression of many genes including MDM2. The delicate balance of this autoregulatory loop is crucial for the maintenance of the genome and control of the cell cycle and apoptosis. MDM2 hyperactivity, due to amplification/overexpression or mutational inactivation of the ARF locus, inhibits the function of wild-type p53 and can lead to the development of a wide variety of cancers. Thus, the development of anti-MDM2 therapies may restore normal p53 function in tumor cells and induce growth suppression and apoptosis. We report here a novel high-throughput fluorescence polarization binding assay and its application in rank ordering small-molecule inhibitors that block the binding of MDM2 to a p53-derived fluorescent peptide.

Development of a fluorescence polarization bead-based coupled assay to target different activity/conformation states of a protein kinase

Most of the protein kinase inhibitors being developed are directed toward the adenosine triphosphate (ATP) binding site that is highly conserved in many kinases. A major issue with these inhibitors is the specificity for a given kinase. Structure determination of several kinases has shown that protein kinases adopt distinct conformations in their inactive state, in contrast to their strikingly similar conformations in their active states. Hence, alternative assay formats that can identify compounds targeting the inactive form of a protein kinase are desirable. The authors describe the development and optimization of an Immobilized Metal Assay for Phosphochemicals (IMAP)-based couple d assay using PDK1 and inactive Akt-2 enzymes. PDK1 phosphorylates Akt-2 at Thr 309 in the catalytic domain, leading to enzymatic activation. Activation of Akt by PDK1 is measured by quantitating the phosphorylation of Akt-specific substrate peptide using the IMAP assay format. This IMAP-coupled assay has been formatted in a 384-well microplate format with a Z' of 0.73 suitable for high-throughput screening. This assay was evaluated by screening the biologically active sample set LOPAC trade mark and validated with the protein kinase C inhibitor staurosporine. The IC(50) value generated was comparable to the value obtained by the radioactive (33)P-gamma-ATP flashplate transfer assay. This coupled assay has the potential to identify compounds that target the inactive form of Akt and prevent its activation by PDK1, in addition to finding inhibitors of PDK1 and activated Akt enzymes.

Improving tolerance of Candida antarctica lipase B towards irreversible thermal inactivation through directed evolution

To expand the functionality of lipase B from Candida antarctica (CALB) we have used directed evolution to create CALB mutants with improved resistance towards irreversible thermal inactivation. Two mutants, 23G5 and 195F1, were generated with over a 20-fold increase in half-life at 70 degrees C compared with the wild-type CALB (WT-CALB). The increase in half-life was attributed to a lower propensity of the mutants to aggregate in the unfolded state and to an improved refolding. The first generation mutant, 23G5, obtained by error-prone PCR, had two amino acid mutations, V210I and A281E. The second generation mutant, 195F1, derived from 23G5 by error-prone PCR, had one additional mutation, V221D. Amino acid substitutions at positions 221 and 281 were determined to be critical for lipase stability, while the residue at position 210 had only a marginal effect. The catalytic efficiency of the mutants with p-nitrophenyl butyrate and 6,8-difluoro-4-methylumbelliferyl octanoate was also found to be superior to that of WT-CALB.

Novel tricyclic inhibitors of farnesyl protein transferase. Biochemical characterization and inhibition of Ras modification in transfected Cos cells

Ras protooncogenes encode 21-kDa membrane-associated guanine nucleotide-binding proteins, which play a critical role in control of cellular proliferation and differentiation. Oncogenic, activated forms of Ras proteins are associated with a broad range of human cancers. The elucidation of the post-translational modifications that occur at the carboxyl terminus of Ras and the demonstration that farnesylation of Ras by farnesyl protein transferase is essential for Ras-induced cellular transformation has opened up a new and promising approach to the development of anti-Ras therapeutics. We report here a novel series of potent farnesyl protein transferase (FPT) inhibitors, represented by SCH 44342. This compound inhibits both rat brain and recombinant human FPT with an IC50 of approximately 250 nM, while it is only weakly active against rat brain geranylgeranyl protein transferase-1 (IC50 > 114 microM). FPT inhibition has been observed using both Ha-Ras protein and Ki-Ras-derived peptide substrates in two different assay formats. SCH 44342 and its analogs also inhibit farnesylation of Ras in Cos cells transiently expressing [Val12]Ha-Ras with IC50 values in the low micromolar range. At these concentrations they do not inhibit sterol biosynthesis or geranylgeranylation of protein. In addition, we observed that Cos cells undergo pronounced morphological changes upon overexpression of [Val12]activated forms of Ha-Ras containing COOH-terminal sequences allowing farnesylation (CVLS) or geranylgeranylation (CVLL) but not upon overexpression of activated Ras lacking the isoprenylated Cys (SVLS). Ras-induced morphological changes can be partially reverted with lovastatin. Importantly, SCH 44342 can block morphological changes induced by [Val12]Ha-Ras-CVLS but not [Val12]Ha-Ras-CVLL. Recently, a number of other FPT inhibitors have been reported. Most of the compounds reported to have cell-based activity are peptidomimetic analogs of the CAAX substrate. Our FPT inhibitors are novel in that although they compete with Ras protein in kinetic experiments they are entirely nonpeptidic in nature, they do not have oxidizable sulfhydryl functions, and they are active in cells at low micromolar concentrations.

A point mutation of human interferon gamma abolishes receptor recognition

We identified a single amino acid mutation that abolished the bioactivity of human IFN gamma. The mutation was identified by screening a mutagenized IFN gamma expression library for molecules with altered biological activity. The mutant protein was expressed at high levels in Escherichia coli, and remained soluble upon purification. However, the protein was completely inactive in all IFN gamma assays investigated, exhibiting less than 0.0006% of the specific activity of native IFN gamma antiviral activity. Sequencing the plasmid DNA encoding this mutant protein showed that the histidine at position 111 of native human IFN gamma is changed to aspartic acid (IFN gamma/H111D). Other mutations at this site showed that only hydrophobic amino acids at position 111 maintain significant, though low, biological activity. Structural characterization of the IFN gamma/H111D protein by NMR as well as CD spectroscopy demonstrated that the protein has limited conformational differences from native IFN gamma. Models of the X-ray crystal structure of human IFN gamma [Ealick, P.E., W.J. Cook, S. Vijay-Kumar, M. Carson, T.L. Nagabhushan, P.P. Trotta and C.E. Bugg (1991) Science, 252, 698-702] suggest that this histidine residue is located at a severe 55 degrees bend in the C-terminal F helix. We conclude that H111 lies within or affects the receptor binding domain of human IFN gamma.