Recent studies suggest that targeting transcriptional machinery can lead to potent and selective anticancer effects in cancers dependent on high and constant expression of certain transcription ...factors for growth and survival. Cyclin-dependent kinase 7 (CDK7) is the catalytic subunit of the CDK-activating kinase complex. Its function is required for both cell-cycle regulation and transcriptional control of gene expression. CDK7 has recently emerged as an attractive cancer target because its inhibition leads to decreased transcript levels of oncogenic transcription factors, especially those associated with super-enhancers. Here, we describe a selective CDK7 inhibitor SY-1365, which is currently in clinical trials in populations of patients with ovarian and breast cancer (NCT03134638).
, SY-1365 inhibited cell growth of many different cancer types at nanomolar concentrations. SY-1365 treatment decreased MCL1 protein levels, and cancer cells with low BCL2L1 (BCL-XL) expression were found to be more sensitive to SY-1365. Transcriptional changes in acute myeloid leukemia (AML) cell lines were distinct from those following treatment with other transcriptional inhibitors. SY-1365 demonstrated substantial antitumor effects in multiple AML xenograft models as a single agent; SY-1365-induced growth inhibition was enhanced in combination with the BCL2 inhibitor venetoclax. Antitumor activity was also observed in xenograft models of ovarian cancer, suggesting the potential for exploring SY-1365 in the clinic in both hematologic and solid tumors. Our findings support targeting CDK7 as a new approach for treating transcriptionally addicted cancers. SIGNIFICANCE: These findings demonstrate the molecular mechanism of action and potent antitumor activity of SY-1365, the first selective CDK7 inhibitor to enter clinical investigation.
The NEDD8-activating enzyme (NAE) initiates a protein homeostatic pathway essential for cancer cell growth and survival. MLN4924 is a selective inhibitor of NAE currently in clinical trials for the ...treatment of cancer. Here, we show that MLN4924 is a mechanism-based inhibitor of NAE and creates a covalent NEDD8-MLN4924 adduct catalyzed by the enzyme. The NEDD8-MLN4924 adduct resembles NEDD8 adenylate, the first intermediate in the NAE reaction cycle, but cannot be further utilized in subsequent intraenzyme reactions. The stability of the NEDD8-MLN4924 adduct within the NAE active site blocks enzyme activity, thereby accounting for the potent inhibition of the NEDD8 pathway by MLN4924. Importantly, we have determined that compounds resembling MLN4924 demonstrate the ability to form analogous adducts with other ubiquitin-like proteins (UBLs) catalyzed by their cognate-activating enzymes. These findings reveal insights into the mechanism of E1s and suggest a general strategy for selective inhibition of UBL conjugation pathways.
► NEDD8 E1 catalyzes the formation of a covalent NEDD8-inhibitor adduct with MLN4924 ► The mechanism of adduct formation resembles the normal UBL activation reaction cycle ► Other E1s also synthesize their own UBL-inhibitor adducts with analogs of MLN4924 ► These findings suggest a general strategy for selective inhibition of UBL pathways
CDK7 has emerged as an exciting target in oncology due to its roles in two important processes that are misregulated in cancer cells: cell cycle and transcription. This report describes the discovery ...of SY-5609, a highly potent (sub-nM CDK7 Kd) and selective, orally available inhibitor of CDK7 that entered the clinic in 2020 (ClinicalTrials.gov Identifier: NCT04247126). Structure-based design was leveraged to obtain high selectivity (>4000-times the closest off target) and slow off-rate binding kinetics desirable for potent cellular activity. Finally, incorporation of a phosphine oxide as an atypical hydrogen bond acceptor helped provide the required potency and metabolic stability. The development candidate SY-5609 displays potent inhibition of CDK7 in cells and demonstrates strong efficacy in mouse xenograft models when dosed as low as 2 mg/kg.
CDK7 associates with the 10-subunit TFIIH complex and regulates transcription by phosphorylating the C-terminal domain (CTD) of RNA polymerase II (RNAPII). Few additional CDK7 substrates are known. ...Here, using the covalent inhibitor SY-351 and quantitative phosphoproteomics, we identified CDK7 kinase substrates in human cells. Among hundreds of high-confidence targets, the vast majority are unique to CDK7 (i.e., distinct from other transcription-associated kinases), with a subset that suggest novel cellular functions. Transcription-associated factors were predominant CDK7 substrates, including SF3B1, U2AF2, and other splicing components. Accordingly, widespread and diverse splicing defects, such as alternative exon inclusion and intron retention, were characterized in CDK7-inhibited cells. Combined with biochemical assays, we establish that CDK7 directly activates other transcription-associated kinases CDK9, CDK12, and CDK13, invoking a "master regulator" role in transcription. We further demonstrate that TFIIH restricts CDK7 kinase function to the RNAPII CTD, whereas other substrates (e.g., SPT5 and SF3B1) are phosphorylated by the three-subunit CDK-activating kinase (CAK; CCNH, MAT1, and CDK7). These results suggest new models for CDK7 function in transcription and implicate CAK dissociation from TFIIH as essential for kinase activation. This straightforward regulatory strategy ensures CDK7 activation is spatially and temporally linked to transcription, and may apply toward other transcription-associated kinases.
Diabetes surveillance often requires manual chart review to confirm status and type. This project aimed to derive and validate an EMR-based algorithm using structured data in the era of ICD-10 codes ...for improving screening efficiency. Youth (<20 years) with potential evidence of diabetes based on in- and out-patient visits were identified from EMRs at 3 Children’s Hospitals participating in the SEARCH Study. Charts were reviewed to determine presence and type of diabetes based on provider notes. Two methods were compared: a multinomial regression evaluating 29 predictors, and a deterministic approach based on ratios of ICD-10 codes (≥2 diabetes codes with the most frequently occurring type-specific codes to indicate type). To evaluate performance, data from two hospitals were used for model building and the third for testing. From 8,752 potential cases, 5,308 true cases were identified; T1D (89.2%), T2D (7.5%), Other types (3.3%). Age, race/ethnicity, ICD-10 codes, and medications were the strongest predictors in the multinomial regression. Performance metrics are shown. Both methods performed well for diabetes diagnosis and for classification of T1D (all metrics ≥0.95). For T2D, the regression model had substantially lower sensitivity (0.59 vs. 0.90), but higher positive predictive value (0.80 vs. 0.62). The ICD-10 ratio model is easier to implement and could be combined with targeted chart reviews to increase efficiency for surveillance efforts.
Disclosure
B.J. Wells: None. K.M. Lenoir: None. L.E. Wagenknecht: None. E. Mayer-Davis: None. D. Dabelea: None. J.M. Lawrence: None. C. Pihoker: None. S. Saydah: None. G. Imperatore: None. R. Casanova: None. C.B. Turley: Stock/Shareholder; Self; Abbott Laboratories, AbbVie Inc., CVS/Caremark, Edwards Lifesciences Corporation, Johnson & Johnson, Novartis AG, Pfizer Inc. A.D. Liese: None. D. Standiford: None. R.F. Hamman: None. M.G. Kahn: None. J. Divers: None.
Funding
Centers for Disease Control and Prevention
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