Elevation of effective p53 expression sensitizes wild-type p53 breast cancer cells to CDK7 inhibitor THZ1

RNA Editing-Mediated Correction of TP53 Nonsense Mutations via Lipid Nanoparticle-Delivered Circular ADAR-Recruiting RNAs

Nonsense mutations account for over 20% of disease-associated mutations, which refer to the occurrence of premature termination codons (PTCs) in gene sequences, resulting in truncated and dysfunctional proteins. Nonetheless, due to poor accessibility of precise target sites and the limitations of gene editing tools, there is still a lack of safe, effective, and site-specific approach for correction of nonsense mutations. Here, we designed a circular ADAR-recruiting RNA (Circ-arRNA) for the in vivo RNA editing-mediated repair of the TP53-W53X nonsense mutation. Compared with linear arRNA, Circ-RNA demonstrates strong intracellular stability and high efficiency for site-specific correction of the TP53-W53X nonsense mutant, with no detectable off-target effects on bystander bases. In triple-negative breast cancer TP53-W53X 4T1 cells and tumor-bearing mouse models, we used lipid nanoparticles (LNPs) to encapsulate and deliver Circ-arRNA, which achieved mutation correction efficiencies of 73.32 and 48.48%, respectively. Furthermore, Circ-arRNA LNPs effectively restored full-length p53 protein expression and its functional activity, significantly enhancing the sensitivity of tumor-bearing mice to paclitaxel chemotherapy. Our research demonstrated the safety and efficacy of LNP-based circular arRNA for specifically the repair of nonsense mutations in vivo, highlighting the immense potential of ADAR-mediated editing for correcting such mutations.

Using bioinformatics and artificial intelligence to map the cyclin-dependent kinase 4/6 inhibitor biomarker landscape in breast cancer

A cyclin-dependent kinase 4/6 (CDK4/6) inhibitor combined with endocrine therapy is the standard-of-care for patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer. However, not all patients respond to the treatment, resistance often occurs and efficacy outcomes from early breast cancer trials have been mixed. To identify biomarkers associated with CDK4/6 inhibitor response or resistance, we combined bioinformatic-database analyses, artificial intelligence-assisted literature review, and manual literature review (Embase and OVID Medline; search window: January 2012-October 2022) to compile data to comprehensively describe the CDK4/6 inhibitor biomarker landscape. Based on these results, and validation by external experts, we identified 15 biomarkers of clinical importance (AR , AURKA, ERBB2, ESR1, CCNE1, CDKN1A/B, CDK2, CDK6, CDK7, CDK9, FGFR1/2, MYC, PIK3CA/AKT, RB1 and STAT3) that could guide future breast cancer research.

Exploring the role of aggrephagy-related signatures in immune microenvironment, prognosis, and therapeutic strategies of breast cancer

Breast cancer (BC) is 1 of the most common malignant tumors among women globally. This study aimed to develop a prognostic signature based on aggrephagy-related genes (ARGs). Transcriptomic and clinical data for BC patients were downloaded from the cancer genome atlas and GEO databases. Differential expression analysis, univariate Cox proportional hazards regression and least absolute shrinkage and selection operator Cox regression were employed to construct a prognostic signature. Consensus clustering, evaluation of immune infiltration and drug sensitivity, and gene set enrichment analysis, and development of nomogram were performed. The expression of ARGs was validated using data from the Cancer Cell Line Encyclopedia and clinical samples. Eleven ARGs were abnormally expressed in BC, with 5 showing significant correlations with BC prognosis. Consensus clustering identified 2 molecular subtypes with distinct prognoses. A prognostic signature including 5 ARGs (VIM, TUBB1, TUBA3E, TUBA3D, TUBA1C) was developed, which showed high performance in predicting BC prognosis. The low-risk group showed enrichment in extracellular matrix organization and cell migration processes while chromosome separation was suppressed. Additionally, patients in this group also show activation in several signaling pathways including MAPK, PI3K-AKT, and cAMP pathways, whereas cell cycle and neutrophil extracellular trap formation were significantly inhibited. The signature was also associated with immune infiltration and drug sensitivity. A nomogram incorporating the risk signature, clinical stage and chemotherapy was constructed, demonstrating excellent performance in predicting prognosis. The expression of signature-related genes were validated in patients with BC. This study successfully constructed molecular subtypes and a prognostic signature based on ARGs in BC, and developed a nomogram.

Cyclin-dependent kinase 7 (CDK7) inhibitors as a novel therapeutic strategy for different molecular types of breast cancer

BACKGROUND

Cyclin-dependent kinase (CDK) 7 is aberrantly overexpressed in many types of cancer and is an attractive target for cancer therapy due to its dual role in transcription and cell cycle progression. Moreover, CDK7 can directly modulate the activities of estrogen receptor (ER), which is a major driver in breast cancer. Breast cancer cells have exhibited high sensitivity to CDK7 inhibition in pre-clinical studies.

METHODS

In this review, we provide a comprehensive summary of the latest insights into CDK7 biology and recent advancements in CDK7 inhibitor development for breast cancer treatment. We also discuss the current application of CDK7 inhibitors in different molecular types of breast cancer to provide potential strategies for the treatment of breast cancer.

RESULTS

Significant progress has been made in the development of selective CDK7 inhibitors, which show efficacy in both triple-negative breast cancer (TNBC) and hormone receptor-positive breast cancer (HR+). Moreover, combined with other agents, CDK7 inhibitors may provide synergistic effects for endocrine therapy and chemotherapy. Thus, high-quality studies for developing potent CDK7 inhibitors and investigating their applications in breast cancer therapy are rapidly emerging.

CONCLUSION

CDK7 inhibitors have emerged as a promising therapeutic strategy and have demonstrated significant anti-cancer activity in different subtypes of breast cancer, especially those that have been resistant to current therapies.

CDK7 in breast cancer: mechanisms of action and therapeutic potential

Cyclin-dependent kinase 7 (CDK7) serves as a pivotal regulator in orchestrating cellular cycle dynamics and gene transcriptional activity. Elevated expression levels of CDK7 have been ubiquitously documented across a spectrum of malignancies and have been concomitantly correlated with adverse clinical outcomes. This review delineates the biological roles of CDK7 and explicates the molecular pathways through which CDK7 exacerbates the oncogenic progression of breast cancer. Furthermore, we synthesize the extant literature to provide a comprehensive overview of the advancement of CDK7-specific small-molecule inhibitors, encapsulating both preclinical and clinical findings in breast cancer contexts. The accumulated evidence substantiates the conceptualization of CDK7 as a propitious therapeutic target in breast cancer management.

Dose escalation and expansion cohorts in patients with advanced breast cancer in a Phase I study of the CDK7-inhibitor samuraciclib

Samuraciclib is a selective oral CDK7-inhibitor. A multi-modular, open-label Phase I study to evaluate safety and tolerability of samuraciclib in patients with advanced malignancies was designed (ClinicalTrials.gov: NCT03363893). Here we report results from dose escalation and 2 expansion cohorts: Module 1A dose escalation with paired biopsy cohort in advanced solid tumor patients, Module 1B-1 triple negative breast cancer (TNBC) monotherapy expansion, and Module 2A fulvestrant combination in HR+/HER2- breast cancer patients post-CDK4/6-inhibitor. Core study primary endpoints are safety and tolerability, and secondary endpoints are pharmacokinetics (PK), pharmacodynamic (PD) activity, and anti-tumor activity. Common adverse events are low grade nausea, vomiting, and diarrhea. Maximum tolerated dose is 360 mg once daily. PK demonstrates dose proportionality (120 mg-480 mg), a half-life of approximately 75 hours, and no fulvestrant interaction. In dose escalation, one partial response (PR) is identified with disease control rate of 53% (19/36) and reduction of phosphorylated RNA polymerase II, a substrate of CDK7, in circulating lymphocytes and tumor tissue. In TNBC expansion, one PR (duration 337 days) and clinical benefit rate at 24 weeks (CBR) of 20.0% (4/20) is achieved. In combination with fulvestrant, 3 patients achieve PR with CBR 36.0% (9/25); in patients without detectable TP53-mutation CBR is 47.4% (9/19). In this study, samuraciclib exhibits tolerable safety and PK is supportive of once-daily oral administration. Clinical activity in TNBC and HR+/HER2-breast cancer post-CDK4/6-inhibitor settings warrants further evaluation.