Discovery of MK-4688: an Efficient Inhibitor of the HDM2-p53 Protein-Protein Interaction.

Identification of low-dose, low-molecular-weight, drug-like inhibitors of protein-protein interactions (PPIs) is a challenging area of research. Despite the challenges, the therapeutic potential of PPI inhibition has driven significant efforts toward this goal. Adding to recent success in this area, we describe herein our efforts to optimize a novel purine carboxylic acid-derived inhibitor of the HDM2-p53 PPI into a series of low-projected dose inhibitors with overall favorable pharmacokinetic and physical properties. Ultimately, a strategy focused on leveraging known binding hot spots coupled with biostructural information to guide the design of conformationally constrained analogs and a focus on efficiency metrics led to the discovery of MK-4688 (compound 56), a highly potent, selective, and low-molecular-weight inhibitor suitable for clinical investigation.

Comparison of the effectiveness of whole-brain radiotherapy plus temozolomide versus whole-brain radiotherapy in treating brain metastases based on a systematic review of randomized controlled trials.

Temozolomide (TMZ) combination with whole-brain radiotherapy (WBRT) has been tested by many randomized controlled trials in the treatment of brain metastases (BMs) in China and other countries. We performed an up-to-date meta-analysis to determine (i) the log odds ratios (LORs) of objective response (ORR) and adverse effects (AEs) for all-grade, and (ii) the T value of mean overall survival in patients with BMs treated with WBRT combined with TMZ versus WBRT alone. PubMed, Chinese National Knowledge Infrastructure, and WanFang Data were searched for articles published up to 28 January 2015. Eligible studies were selected according to the PRISMA statement. ORR, AEs, and 95% confidence intervals were calculated using random-effects models. Eighteen studies were included in our analysis. A total of 1028 participants were enrolled. Summary LORs of ORR were 1.0239 (P<0.0001) on comparing WBRT plus TMZ with WBRT ORR (n=17). The overall mean difference of mean overall survival (n=17) between TMZ plus WBRT and WBRT was 2.2505 weeks (P=0.02185). There was a significant difference between WBRT plus TMZ and WBRT alone with a LOR of AEs for all-grade of (i) 0.923 for gastrointestinal toxicity and (ii) 0.7978 for myelosuppression. Sensitivity analysis and subgroup analysis were also performed. The 18 eligible randomized controlled trials demonstrated that the combination of WBRT and TMZ significantly improves the ORR and is statistically insignificant in prolonging the survival of patients with BMs. In addition, an increase in the incidence of gastrointestinal toxicity and myelosuppression was significant for all-grade.

Overcoming mutagenicity and ion channel activity: optimization of selective spleen tyrosine kinase inhibitors.

Development of a series of highly kinome-selective spleen tyrosine kinase (Syk) inhibitors with favorable druglike properties is described. Early leads were discovered through X-ray crystallographic analysis, and a systematic survey of cores within a selected chemical space focused on ligand binding efficiency. Attenuation of hERG ion channel activity inherent within the initial chemotype was guided through modulation of physicochemical properties including log D, PSA, and pKa. PSA proved most effective for prospective compound design. Further profiling of an advanced compound revealed bacterial mutagenicity in the Ames test using TA97a Salmonella strain, and subsequent study demonstrated that this mutagenicity was pervasive throughout the series. Identification of intercalation as a likely mechanism for the mutagenicity-enabled modification of the core scaffold. Implementation of a DNA binding assay as a prescreen and models in DNA allowed resolution of the mutagenicity risk, affording molecules with favorable potency, selectivity, pharmacokinetic, and off-target profiles.