Search

Black mothers have never fit the hegemonic white standard of motherhood. The bad mother narrative has been superimposed on Black women through controlling images. Through in-depth interviews with formerly incarcerated Black mothers, I demonstrate how formerly incarcerated Black women invert controlling images through how they frame their mothering choices. Their reframing of their mothering choices reveals that formerly incarcerated Black mothers have mothering practices that entail good mothering and goes beyond the white imaginary. These mothering practices reveal a redefinition of motherhood that provides greater understanding of how formerly incarcerated Black mothers understand and make sense of their mothering choices.

Pooled mouse PK model parameters for AZD3229

Summary of plasma protein binding (% unbound) of AZD3229

Pharmacokinetic parameters for standard of care compounds in human and in mouse

Legends for supplementary figures and tables

GI90 for each mutation in the Ba/F3 cell viability assay panel for AZD3229, SoC agents and investigational agents

Fraction Absorbed (Fabs) as a Function of AZD3229 Dose using GI-SIM tool

Goodness of fit plots of PK/PD model fit for AZD3229

PKPD efficacy data of KIT probe compound (AZ12607208)

Graphical description of the PKPD model used to describe effects of AZD3229 in mouse tumor models

PK model fit for AZD3229 dosed orally in the mouse

Purpose:The emergence of secondary mutations is a cause of resistance to current KIT inhibitors used in the treatment of patients with gastrointestinal stromal tumors (GIST). AZD3229 is a selective inhibitor of wild-type KIT and a wide spectrum of primary and secondary mutations seen in patients with GIST. The objective of this analysis is to establish the pharmacokinetic–pharmacodynamic (PKPD) relationship of AZD3229 in a range of mouse GIST tumor models harboring primary and secondary KIT mutations, and to benchmark AZD3229 against other KIT inhibitors.Experimental Design:A PKPD model was developed for AZD3229 linking plasma concentrations to inhibition of phosphorylated KIT using data generated from several in vivo preclinical tumor models, and in vitro data generated in a panel of Ba/F3 cell lines.Results:AZD3229 drives inhibition of phosphorylated KIT in an exposure-dependent manner, and optimal efficacy is observed when >90% inhibition of KIT phosphorylation is sustained over the dosing interval. Integrating the predicted human pharmacokinetics into the mouse PKPD model predicts that an oral twice daily human dose greater than 34 mg is required to ensure adequate coverage across the mutations investigated. Benchmarking shows that compared with standard-of-care KIT inhibitors, AZD3229 has the potential to deliver the required target coverage across a wider spectrum of primary or secondary mutations.Conclusions:We demonstrate that AZD3229 warrants clinical investigation as a new treatment for patients with GIST based on its ability to inhibit both ATP-binding and A-loop mutations of KIT at clinically relevant exposures.

PKPD data utilized to establish the level and duration of target inhibition required for AZD3229

Purpose:The emergence of secondary mutations is a cause of resistance to current KIT inhibitors used in the treatment of patients with gastrointestinal stromal tumors (GIST). AZD3229 is a selective inhibitor of wild-type KIT and a wide spectrum of primary and secondary mutations seen in patients with GIST. The objective of this analysis is to establish the pharmacokinetic–pharmacodynamic (PKPD) relationship of AZD3229 in a range of mouse GIST tumor models harboring primary and secondary KIT mutations, and to benchmark AZD3229 against other KIT inhibitors.Experimental Design:A PKPD model was developed for AZD3229 linking plasma concentrations to inhibition of phosphorylated KIT using data generated from several in vivo preclinical tumor models, and in vitro data generated in a panel of Ba/F3 cell lines.Results:AZD3229 drives inhibition of phosphorylated KIT in an exposure-dependent manner, and optimal efficacy is observed when >90% inhibition of KIT phosphorylation is sustained over the dosing interval. Integrating the predicted human pharmacokinetics into the mouse PKPD model predicts that an oral twice daily human dose greater than 34 mg is required to ensure adequate coverage across the mutations investigated. Benchmarking shows that compared with standard-of-care KIT inhibitors, AZD3229 has the potential to deliver the required target coverage across a wider spectrum of primary or secondary mutations.Conclusions:We demonstrate that AZD3229 warrants clinical investigation as a new treatment for patients with GIST based on its ability to inhibit both ATP-binding and A-loop mutations of KIT at clinically relevant exposures.

JAK1, JAK2, JAK3, and TYK2 belong to the JAK (Janus kinase) family. They play critical roles in cytokine signaling. Constitutive activation of JAK/STAT pathways is associated with a wide variety of...

We report the first disclosure of IRAK3 degraders in the scientific literature. Taking advantage of an opportune byproduct obtained during our efforts to identify IRAK4 inhibitors, we identified ready-to-use, selective IRAK3 ligands in our compound collection with the required properties for conversion into proteolysis-targeting chimera (PROTAC) degraders. This work culminated with the discovery of PROTAC 23, which we demonstrated to be a potent and selective degrader of IRAK3 after 16 h in THP1 cells. 23 induced proteasome-dependent degradation of IRAK3 and required both CRBN and IRAK3 binding for activity. We conclude that PROTAC 23 constitutes an excellent in vitro tool with which to interrogate the biology of IRAK3.

JAK1, JAK2, JAK3, and TYK2 belong to the JAK (Janus kinase) family. They play critical roles in cytokine signaling. Constitutive activation of JAK/STAT pathways is associated with a wide variety of diseases. Particularly, pSTAT3 is observed in response to the treatment with inhibitors of oncogenic signaling pathways such as EGFR, MAPK, and AKT and is associated with resistance or poorer response to agents targeting these pathways. Among the JAK family kinases, JAK1 has been shown to be the primary driver of STAT3 phosphorylation and signaling; therefore, selective JAK1 inhibition can be a viable means to overcome such treatment resistances. Herein, an account of the medicinal chemistry optimization from the promiscuous kinase screening hit

Gastrointestinal stromal tumor (GIST) is the most common human sarcoma driven by mutations in KIT or platelet-derived growth factor α (PDGFRα). Although first-line treatment, imatinib, has revolutionized GIST treatment, drug resistance due to acquisition of secondary KIT/PDGFRα mutations develops in a majority of patients. Second- and third-line treatments, sunitinib and regorafenib, lack activity against a plethora of mutations in KIT/PDGFRα in GIST, with median time to disease progression of 4 to 6 months and inhibition of vascular endothelial growth factor receptor 2 (VEGFR2) causing high-grade hypertension. Patients with GIST have an unmet need for a well-tolerated drug that robustly inhibits a range of KIT/PDGFRα mutations. Here, we report the discovery and pharmacological characterization of AZD3229, a potent and selective small-molecule inhibitor of KIT and PDGFRα designed to inhibit a broad range of primary and imatinib-resistant secondary mutations seen in GIST. In engineered and GIST-derived cell lines, AZD3229 is 15 to 60 times more potent than imatinib in inhibiting KIT primary mutations and has low nanomolar activity against a wide spectrum of secondary mutations. AZD3229 causes durable inhibition of KIT signaling in patient-derived xenograft (PDX) models of GIST, leading to tumor regressions at doses that showed no changes in arterial blood pressure (BP) in rat telemetry studies. AZD3229 has a superior potency and selectivity profile to standard of care (SoC) agents-imatinib, sunitinib, and regorafenib, as well as investigational agents, avapritinib (BLU-285) and ripretinib (DCC-2618). AZD3229 has the potential to be a best-in-class inhibitor for clinically relevant KIT/PDGFRα mutations in GIST.

10-20% of lung adenocarcinoma patients harbour activating mutations in EGFR. Although treatment with the EGFR kinase inhibitor osimertinib has improved overall survival in such patients, almost all patients ultimately develop drug resistance. In many cases the molecular resistance mechanisms remain unknown. A systematic identification of the involved genes and pathways is critical to overcome osimertinib resistance. To define the resistance landscape of EGFR kinase inhibition we performed genome-wide gain and loss of function CRISPR screens in EGFR mutant lung cancer cell lines treated with osimertinib. Resistance hits were enriched for genes in previously identified resistance pathways including PI3K (PTEN, TSC2), MAPK (NF1, MET), cell death (BCL2L11, BAX), the mediator complex (MED24, MED19) and ubiquitination (KCTD5, LZTR1). A secondary screen of 63 resistance genes that combined high content microscopy with CRISPR gene knockouts demonstrated that 21% (13/63) of genes were associated with increased nuclear localisation of YAP1/WWTR1, indicating transcriptional activation of the Hippo pathway. According to our screening data, many resistance hits mapped onto the Hippo signaling axis - upstream regulators (NF2, AMOTL2), core signaling genes (LATS1, LATS2), main effectors (WWTR1, YAP1), transcriptional co-effectors (TEAD3, FOSL1, VGLL4) and the SWI/SNF complex (ARID2, SMARCA4, SMARCB1, PBRM1). Hippo signaling is mediated through YAP1 and WWTR1 which bind to TEAD transcription factors and activate transcriptional programs affecting cell proliferation and apoptosis. We confirmed using CRISPR that knockout (NF2) or overexpression (YAP1, WWTR1) of key Hippo genes in the EGFR mutant lung cancer cell lines PC-9, HCC827 and HCC4006 resulted in up to 60-fold increased resistance to osimertinib and elevated activity of a TEAD reporter system, indicating activation of Hippo transcriptional programs. To maintain osimertinib resistance, expression of both YAP1 and WWTR1 was necessary, suggesting non-redundant roles for both Hippo main effectors in mediating osimertinib resistance. The combination of osimertinib and a TEAD inhibitor (MYF-01-37) reversed the resistance phenotype in NF2 KO cell line models in long-term proliferation assays and also substantially repressed the emergence of drug-tolerant persister cells in PC-9, HCC827 and HCC4006 cell lines following osimertinib treatment. These cells exhibited an enhanced apoptotic response when treated with combination of osimertinib and TEAD inhibitor. Consequently, we propose Hippo signaling as an important target mechanism for the prevention of resistance to osimertinib. Citation Format: Matthias Pfeifer, Jonathan S. Brammeld, Stacey Price, Matthew Martin, Hannah Thorpe, Aurelie Bornot, Erica Banks, Nin Guan, Shanade Dunn, Maria Luisa Guerriero, Daniel O'Neill, James Pilling, Davide Gianni, James Brownell, Paul Smith, Ultan McDermott. Gain and loss of function genome-wide CRISPR screens identify Hippo signaling as an important driver of resistance in EGFR mutant lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1100.