Optimization of a series of novel, potent and selective Macrocyclic SYK inhibitors

Spleen tyrosine kinase (SYK) is a non-receptor cytoplasmic kinase. Due to its pivotal role in B cell receptor and Fc-receptor signalling, inhibition of SYK has been a target of interest in a variety of diseases. Herein, we report the use of structure-based drug design to discover a series of potent macrocyclic inhibitors of SYK, with excellent kinome selectivity and in vitro metabolic stability. We were able to remove hERG inhibition through the optimization of physical properties, and utilized a pro-drug strategy to address permeability challenges.

EFFICACY OF THE ALGORITHMIC STEP-UP APPROACH OF INTERVENTIONAL TREATMENT OF PATIENTS WITH ACUTE NECROTIZING PANCREATITIS

Aim - to estimate the efficacy of the algorithmic step-up approach of interventional treatment of acute necrotizing pancreatitis (ANP).; We performed a prospective observational cohort study of the efficacy of the developed approach of surgical treatment of 317 patients with different morphological forms of ANP. The following parameters were collected for each episode: length of hospital stay, mortality rate, occurrence of organ failure and local complications.; Transcutaneous punction/drainages were applied as the first step in 37 patients with acute necrotic collections. In the presence of walled-off pancreatic necrosis (WOPN) endoscopic procedures were preferred in case their close localization to the stomach or duodenum in 65 observations. Initial surgical treatment was not effective in 18.8% and video-assisted retroperitoneal debridement in patients with ANP or necrosectomies under endoscopic control in cases of WOPN were performed. Involuntary laparotomic necrosectomies were conducted in 14.5% of patients as a final step of the suggested algorithmic approach. During postoperative period complications occurred in 28.3% of patients. They included 7 new episodes of organ failure, 4 cases of arosive hemorrhage, and 5 cases of pancreatic and duodenal fistulas. Overall mortality rate was 3.3%, after laparotomic surgical treatment - 6.5%.; Surgical treatment in patients with ANP based on the developed algorithmic step-up approach is followed by acceptable complication and mortality level.

Novel potent and selective pyrazolylpyrimidine-based SYK inhibitors

Hybridisation of amino-pyrimidine based SYK inhibitors (e.g. 1a) with previously reported diamine-based SYK inhibitors (e.g. TAK-659) led to the identification and optimisation of a novel pyrimidine-based series of potent and selective SYK inhibitors, where the original aminomethylene group was replaced by a 3,4-diaminotetrahydropyran group. The initial compound 5 achieved excellent SYK potency. However, it suffered from poor permeability and modest kinase selectivity. Further modifications of the 3,4-diaminotetrahydropyran group were identified and the interactions of those groups with Asp512 were characterised by protein X-ray crystallography. Further optimisation of this series saw mixed results where permeability and kinase selectivity were increased and oral bioavailability was achieved in the series, but at the expense of potent hERG inhibition.

Identification of a novel series of azabenzimidazole-derived inhibitors of spleen tyrosine kinase

Spleen Tyrosine Kinase (SYK) is a well-studied enzyme with therapeutic applications in oncology and autoimmune diseases. We identified an azabenzimidazole (ABI) series of SYK inhibitors by mining activity data of 86,000 compounds from legacy biochemical assays with SYK and other homologous kinases as target enzymes. A structure-based design and hybridization approach was then used to improve the potency and kinase selectivity of the hits. Lead compound 23 from this novel ABI series has a SYK IC₅₀ = 0.21 nM in a biochemical assay and inhibits growth of SUDHL-4 cells at a GI₅₀ = 210 nM.

Abstract 2500: Transient CDK9 inhibition with AZD4573 modulates Bfl-1 in preclinical lymphoma models

AZD4573 is a selective cyclin-dependent kinase 9 (CDK9) inhibitor under clinical development in patients with hematological malignancies. Transient CDK9 inhibition serves as an orthogonal approach for targeting Mcl-1, a labile anti-apoptotic protein essential for the survival of cancer cells. Across-broad hematological cancer models, anti-tumor responses with AZD4573 strongly correlate with selective Mcl-1 inhibitors, such as AZD5991 (R2=0.8). Despite compelling evidence for an Mcl-1 dependent mechanism of action, we also observed a subset of lymphoma models more sensitive to CDK9 inhibition compared to Mcl-1 inhibition, suggesting acute CDK9 inhibition could be targeting other labile proteins beyond Mcl-1 to induce apoptosis. We identified Bfl-1 as one such potential target and demonstrate lymphoma models expressing Bfl-1 are highly sensitive to CDK9 inhibition.

Bfl-1 belongs to the Bcl-2 family of anti-apoptotic proteins and was detected in over 20% of lymphoma cell lines evaluated (n=33). Cycloheximide experiments indicate Bfl-1 has a short protein half-life (<1h), similar to Mcl-1. Therefore, treatment with 100nM of AZD4573 in diffuse large B-cell lymphoma cell lines OCILY10 and TMD8 caused rapid down-regulation of both Mcl-1 and Bfl-1 by 4h, resulting in caspase cleavage by 6h. Evaluation of caspase activation following 6h treatment revealed an average maximum effect of 87% for AZD4573 compared to 45% with Mcl-1 inhibition, suggesting these cell lines are not exclusively Mcl-1-dependent. The hypothesis that survival of lymphoma cells may be co-dependent on both Mcl-1 and Bfl-1 was evaluated by siRNA knockdown. Following a dose-dependent suppression of Bfl-1 protein (>80%) in OCILY10 and TMD8 cells, viability loss was minimal (<30% reduction relative to control). However, when Bfl-1 knockdown cells were treated for 6h with an Mcl-1 inhibitor, the maximum caspase activation increased to over 90% in both cell lines, phenocopying a similar magnitude achieved with AZD4573-mediated CDK9 inhibition. In these models, depletion of both Bfl-1 and Mcl-1 was necessary to induce maximum apoptosis, with studies ongoing to evaluate single-gene Bfl-1 dependency in additional lymphoma models.

Consistent with the in vitro phenotype, intermittent dosing of the ABC-DLBCL xenografts OCILY10 and TMD8 with AZD4573 caused robust tumor regressions (198 and 184% TGI, respectively). AZD4573-mediated anti-tumor activity was associated with pharmacodynamic reductions of pSer2-RNAPII, Mcl-1 and Bfl-1, followed by caspase activation. Collectively, these findings support the ability to target Bfl-1 via CDK9 inhibition. Given the current absence of clinical small molecule Bfl-1 inhibitors and expanded monotherapy activity compared to selective Mcl-1 inhibition in a subset of preclinical models, CDK9 inhibitors have tremendous therapeutic potential in the treatment of patients with Bfl-1-expressing lymphoma.

Citation Format: Scott Boiko, Theresa Proia, Maryann San Martin, Lisa Drew, Wenlin Shao, Justin Cidado. Transient CDK9 inhibition with AZD4573 modulates Bfl-1 in preclinical lymphoma models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2500.

Abstract 297: AZD4573: Mechanistic PKPD model linking CDK9 inhibition to Mcl1 depletion and induction of apoptosis in preclinical AML model

Cyclin-dependent kinase 9 (CDK9) regulates elongation of transcription through phosphorylation of RNA polymerase II (pSer2-RNAPII), and its short-term inhibition results in the selective downregulation of genes with short-lived transcripts and labile proteins - including the anti-apoptotic protein Mcl1. AZD4573 is a selective inhibitor of CDK9 with short pharmacokinetic (PK) half-life. Intermittent dosing of AZD4573 in mouse MV411 (AML cell line) xenograft models results in progressive reduction in tumor volume with the mechanism of action believed to be via induction of apoptosis following depletion of Mcl1. The aim of this work was to derive a quantitative understanding of the relationships between extent and duration of CDK9 inhibition, depletion of Mcl1 and rate of induction of apoptosis in MV411 tumor cells.

A mechanistic model has been established that quantitatively and dynamically connects AZD4573 plasma and tumor PK to the rate and extent of modulation of pSer2-RNAPII and Mcl1 in the tumor and rate of induction of cell death (as measured by reduction in tumor volume). Tumor pSer2-RNAPII and Mcl1 pharmacodynamics were modeled using a series of linked indirect response models. Production rate of pSer2-RNAPII was modeled as being directly inhibited by AZD4573 concentration in the tumor. Production rate of Mcl1 was linked to pSer2-RNAPII via a series of transit compartments to capture the transcription/translation driven delay in onset of response. Induction of intrinsic apoptosis in the MV411 tumor cells was modelled as being inhibited by Mcl1.

Tumor pSer2-RNAPII exhibited a rapid, dose-dependent decrease following IP dosing of AZD4573 in mice. The free concentration of AZD4573 that resulted in half-maximal inhibition of pSer2-RNAPII production rate was estimated to be in the range 11-21 nM. Following a brief delay, tumor Mcl1 also exhibited a relatively rapid decrease that was proportional to the pSer2-RNAPII response. Mcl1 protein half-life was estimated to be 0.3 hr. Rate of induction of apoptosis could be decribed as a saturable first-order process (Kmax ~ 0.2 hr-1) and appeared to exhibit a steep response to the depletion of Mcl1, with reduction of Mcl1 to 25% (of the baseline value) being estimated to result in half-maximal rate of induction of apoptosis in the MV411 cells.

The described MV411 PKPD/efficacy model has been assumed to be representative of AML in human patients and was used to derive preliminary predictions of clinical efficacy at a range of possible IV dosing regimens.

Citation Format: Douglas Ferguson, Theresa Proia, Justin Cidado, Scott Boiko, Maryann San Martin, Steven Criscione, Wenlin Shao, Lisa Drew. AZD4573: Mechanistic PKPD model linking CDK9 inhibition to Mcl1 depletion and induction of apoptosis in preclinical AML model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 297.

Variability of the SIRT3 gene, human silent information regulator Sir2 homologue, and survivorship in the elderly

The human sirtuin 3 (SIRT3) gene encodes a putative mitochondrial NAD-dependent deacetylase (SIRT3) which belongs to the evolutionary conserved family of sirtuin 2 proteins. Studies in model organisms have demonstrated that SIR2 genes control lifespan, while no data are available regarding a possible role of SIRT3 in human longevity. By analysing the genotype-specific survival function relevant to the G477T marker of SIRT3, we found that in males the TT genotype increases (p=0.0272), while the GT genotype decreases (p=0.0391) survival in the elderly. Since SIRT3 lies in a chromosomal region (11p15.5) where four genes potentially associated with longevity are located (HRAS1, Insulin-like Growth Factor 2, Proinsulin, and Tyrosine Hydroxylase) we tested for linkage-disequilibrium between G477T alleles and alleles of the above genes. The disequilibrium was not significant in any case, thus suggesting that SIRT3 itself, or a gene strictly linked to SIRT3, may have a role in human longevity.

Sweet's syndrome as an initial manifestation of pediatric human immunodeficiency virus infection

We report a 3-month-old infant in whom Sweet's syndrome was a presenting manifestation of pediatric human immunodeficiency virus infection. Although rare in children, Sweet's syndrome may be associated with certain infections and malignancies. The diagnosis of Sweet's syndrome in a child should always prompt a thorough evaluation to assess for an associated systemic disease.

Treatment of diaper dermatitis

Diaper rash therapy can be as simple as A, B, C, D, and E if you are able to identify generic diaper rash and exclude other causes. Components of diaper rash treatment include airing, barrier and other tropical product application, cleansing of the diaper area, diaper selection, and education of caregivers. Diaper rash therapy can be letter-perfect.

Diapers and diaper rashes

The diaper-wearing population has expanded from infants and children to include adults, especially the elderly. Nurses caring for patients over a wide age range are commonly asked for advice about diapering choices, and for guidance in evaluation, prophylaxis, and treatment of diaper rashes. Two different diaper types, disposables and reusables, and the advantages and disadvantages of each are discussed. A systematic approach is presented for the nursing evaluation of common diaper rashes and their differentiation from rarer skin eruptions of the groin and perineum in diaper-wearing persons.

Generalized pustulation as a manifestation of the anticonvulsant hypersensitivity syndrome

BACKGROUND

-The anticonvulsant hypersensitivity syndrome is characterized by the development of fever, rash, lymphadenopathy, and hepatitis, and is associated with leukocytosis and eosinophilia. This article describes the unusual development of a follicular pustular eruption in two patients as a manifestation of this syndrome.

OBSERVATIONS

-This pustular eruption most commonly develops on the face and scalp but may subsequently become generalized. While cultures of the pustules are negative, biopsy specimens reveal a dilated follicular infundibulum filled with neutrophils. Recognition of cutaneous pustulation as a potential manifestation of this syndrome is important, as a generalized pustular eruption developing in a febrile patient can easily be confused with an infectious process.

CONCLUSIONS

-The anticonvulsant hypersensitivity syndrome may present with a follicular pustular eruption rather than the more commonly associated macular or papular rash or erythroderma. The three most commonly used anticonvulsants, phenytoin, phenobarbital, and carbamazepine, can each produce an identical hypersensitivity reaction. In addition, in vitro testing has demonstrated that approximately 80% of patients tested to all three medications had positive reactions to each. Furthermore, with in vitro testing researchers are able to predict which anticonvulsants are safe to use, thereby allowing for prospective individualization of therapy. However, this technology is not yet available for widespread use.

Osteomyelitis of the distal phalanges in three children with severe atopic dermatitis

Three children with severe, secondarily infected atopic dermatitis since infancy developed osteomyelitis of the distal phalanges of the hands. The insidious onset of one or more distal subungual black macules was followed by edema, erythema, and pain in the involved fingers. No child had an elevated erythrocyte sedimentation rate or fever, but all had roentgenographic or scintigraphic evidence of bony destruction. In two children, Staphylococcus aureus grew from skin surface cultures; S aureus also grew from nail bed and osseous cultures of the distal phalanges; Streptococcus viridans grew from one child's nail bed. All children had prolonged hospitalizations. In two children, laboratory evaluation of immunologic function disclosed normal findings. We postulate that intense scratching of infected skin coupled with minor trauma to the fingertips created distal subungual microabscesses that spread contiguously to the underlying bone.

Uncombable-hair syndrome

Four children had short, unmanageable, pale blond hair. They had no associated abnormalities and no family histories of abnormal hair. Light microscopy of the hair was normal in three patients, with pili torti present in the fourth. Electron microscopy of hairs from all four children revealed longitudinal grooves in the hair shaft, diagnostic of uncombable-hair syndrome.