Introduction: DNA-dependent protein kinase (DNA-PK) plays a crucial role in the repair of DSBs via non-homologous end joining (NHEJ). Several DNA-PK inhibitors are being investigated for potential anticancer treatment in clinical trials.Area covered: This review aims to give an overview of patents published since 2010 by analyzing the patent space and structure features of scaffolds used in those patents. It also discusses the recent clinical developments and provides perspectives on future challenges and directions in this field.Expert opinion: As a key component of the DNA damage response (DDR) pathway, DNA-PK appears to be a viable drug target for anticancer therapy. The clinical investigation of a DNA-PK inhibitor employs both a monotherapy and a combination strategy. In the combination strategy, a DNA-PK inhibitor is typically combined with a DSB inducer, radiation, a chemotherapy agent, or a PARP inhibitor, etc. Patent analyses suggest that diverse structures comprising different scaffolds from mono-heteroaryl to bicyclic heteroaryl to tricyclic heteroaryl are capable to achieve good DNA-PK inhibitory activity and good DNA-PK selectivity over other closely related enzymes. Several DNA-PK inhibitors are currently being evaluated in clinics, with the hope to get approval in the near future.

V(D)J recombination, during which recognition and repair of broken DNA chains are accomplished by non-homologous end joining pathway, is a critical process in B and T cell development.Null mutations of each enzyme or protein of this pathway result in T- B- NK+ severe combined immunodeficiency whereas hypomorphic mutations result in atypical(leaky)severe combined immunodeficiency forms. We present two siblings with PRKDC (Protein Kinase, DNA-Activated, Catalytic Polypeptide) mutation who presented with granulomatous skin lesions and recurrent lung infections. Primary immune deficiencies may initially present with skin findings. Disruption in central and peripheral B-cell tolerance and impaired intrathymic T-cell maturation,a central player in T-cell tolerance, have been identified as the mechanism of autoimmunity and granuloma seen in patients. The variation in clinical phenotypes of patients with PRKDC mutation suggests that additional factors such as modifying genes, epigenetic and environmental factors may affect the severity and clinical phenotype of the disease. Functional studies during the follow-up and evaluation before and after hematopoeitic stem cell transplantation will hopefully increase our knowledge about the autoimmune and inflammatory process of the disease spectrum.

OBJECTIVE: Non-homologous end joining (NHEJ) is a pathway for repairing DNA double-strand breaks. Recent publications indicated that XRCC5, XRCC6 and XRCC7 genes may participate in the pathogenesis of breast cancer. The aim of this Human Genome Epidemiology (HuGE) review and meta-analysis was to investigate associations between XRCC5, XRCC6 and XRCC7 genetic polymorphisms in the NHEJ pathway and breast cancer risk.
METHODS: Studies focusing on the relationship between genetic polymorphisms in XRCC5, XRCC6 and XRCC7 genes and susceptibility to breast cancer were selected from the Pubmed, Cochrane library, Embase, Web of Science, Springerlink, CNKI and CBM databases. Data were extracted by two independent reviewers. The meta-analysis was performed with Review Manager Version 5.1.6 and STATA Version 12.0 software. The odds ratio (OR) with 95% confidence interval (95%CI) was calculated based on the extracted data.
RESULTS: According to the inclusion criteria, we final included seven studies with a total of 2,864 breast cancer cases and 3,060 healthy controls. Meta-analysis results showed that rs3835 (G>A) and rs828907 (G>T) in XRCC5 gene, and rs132793 (G>A) in XRCC6 gene might increase the risk of breast cancer, while rs132788 G>T and rs6002421 (A>G) might be protective factors. However, there was no relationship between XRCC7 genetic polymorphisms and the risk of breast cancer.
CONCLUSIONS: This meta-analysis suggests that the rs3835 G>A and rs828907 G>T in XRCC5 gene, rs6002421 (A>G), rs132788 (G>T) and rs132793 (G>A) in XRCC6 gene might be risk factors for breast cancer, while the rs132788 (G>T) and rs6002421 (A>G) in XRCC6 gene might be protective.