Statistical method on nonrandom clustering with application to somatic mutations in cancer.

BACKGROUND: Human cancer is caused by the accumulation of tumor-specific mutations in oncogenes and tumor suppressors that confer a selective growth advantage to cells. As a consequence of genomic instability and high levels of proliferation, many passenger mutations that do not contribute to the cancer phenotype arise alongside mutations that drive oncogenesis. While several approaches have been developed to separate driver mutations from passengers, few approaches can specifically identify activating driver mutations in oncogenes, which are more amenable for pharmacological intervention. RESULTS: We propose a new statistical method for detecting activating mutations in cancer by identifying nonrandom clusters of amino acid mutations in protein sequences. A probability model is derived using order statistics assuming that the location of amino acid mutations on a protein follows a uniform distribution. Our statistical measure is the differences between pair-wise order statistics, which is equivalent to the size of an amino acid mutation cluster, and the probabilities are derived from exact and approximate distributions of the statistical measure. Using data in the Catalog of Somatic Mutations in Cancer (COSMIC) database, we have demonstrated that our method detects well-known clusters of activating mutations in KRAS, BRAF, PI3K, and beta-catenin. The method can also identify new cancer targets as well as gain-of-function mutations in tumor suppressors. CONCLUSIONS: Our proposed method is useful to discover activating driver mutations in cancer by identifying nonrandom clusters of somatic amino acid mutations in protein sequences.

Sacubitril/valsartan (LCZ696) significantly reduces aldosterone and increases cGMP circulating levels in a canine model of RAAS activation.

Simultaneous blockade of angiotensin receptors and enhancement of natriuretic peptides (NP) by the first-in-class angiotensin receptor neprilysin (NEP) inhibitor sacubitril/valsartan constitutes an effective approach to treating heart failure. This study examined the effects of sacubitril/valsartan (225 and 675 mg/day) vs. placebo, sacubitril (360 mg/day), valsartan (900 mg/day), and benazepril (5 mg/day) on the dynamics of the renin-angiotensin-aldosterone system (RAAS) and the NP system in dogs. Beagle dogs (n = 18) were fed a low-salt diet (0.05% Na) for 15 days to model RAAS activation observed in clinical heart failure. Drugs were administered once daily during the last 10 days, while the effects on the RAAS and NPs were assessed on Day 1, 5, and 10. Steady-state pharmacokinetics of the test agents were evaluated on Day 5. Compared with placebo, sacubitril/valsartan (675 mg) substantially increased cGMP circulating levels, while benazepril and valsartan showed no effect. Additionally, sacubitril/valsartan (675 mg) and valsartan significantly increased plasma renin activity, angiotensin I and angiotensin II concentrations. Finally, sacubitril/valsartan (both doses), and valsartan significantly decreased plasma aldosterone vs. placebo. Systemic exposure to valsartan following sacubitril/valsartan 675 mg administration was similar to that observed with valsartan 900 mg administration alone. Sacubitril/valsartan favorably modulates the dynamics of the renin and NP cascades through complementary NEP and RAAS inhibition.

Discovery of a Novel Cabazitaxel Nanoparticle-Drug Conjugate (CRLX522) with Improved Pharmacokinetic Properties and Anticancer Effects Using a ß-Cyclodextrin-PEG Copolymer Based Delivery Platform.

Novel nanoparticle-drug conjugates (NDCs) containing diverse, clinically relevant anticancer drug payloads (docetaxel, cabazitaxel, and gemcitabine) were successfully generated and tested in drug discovery studies. The NDCs utilized structurally varied linkers that attached the drug payloads to a ß-cyclodextrin-PEG copolymer to form self-assembled nanoparticles. In vitro release studies revealed a diversity of release rates driven by linker structure-activity relationships (SARs). Improved in vivo pharmacokinetics (PK) for the cabazitaxel (CBTX) NDCs with glycinate-containing (1c) and hexanoate-containing linkers (2c) were demonstrated, along with high and sustained tumor levels (>168 h of released drug in tumor tissues). This led to potent efficacy and survival in both taxane- and docetaxel-resistant in vivo anticancer mouse efficacy models. Overall, the CBTX-hexanoate NDC 2c (CRLX522), demonstrated optimal and improved in vivo PK (plasma and tumor) and efficacy profile versus those of the parent drug, and the results support the potential therapeutic use of CRLX522 as a new anticancer agent.

Bile Acid Sequestration by Cholestyramine Mitigates FGFR4 Inhibition-Induced ALT Elevation.

The FGF19- fibroblast growth factor receptor (FGFR4)-ßKlotho (KLB) pathway plays an important role in the regulation of bile acid (BA) homeostasis. Aberrant activation of this pathway has been described in the development and progression of a subset of liver cancers including hepatocellular carcinoma, establishing FGFR4 as an attractive therapeutic target for such solid tumors. FGF401 is a highly selective FGFR4 kinase inhibitor being developed for hepatocellular carcinoma, currently in phase I/II clinical studies. In preclinical studies in mice and dogs, oral administration of FGF401 led to induction of Cyp7a1, elevation of its peripheral marker 7alpha-hydroxy-4-cholesten-3-one, increased BA pool size, decreased serum cholesterol and diarrhea in dogs. FGF401 was also associated with increases of serum aminotransferases, primarily alanine aminotransferase (ALT), in the absence of any observable adverse histopathological findings in the liver, or in any other organs. We hypothesized that the increase in ALT could be secondary to increased BAs and conducted an investigative study in dogs with FGF401 and coadministration of the BA sequestrant cholestyramine (CHO). CHO prevented and reversed FGF401-related increases in ALT in dogs in parallel to its ability to reduce BAs in the circulation. Correlation analysis showed that FGF401-mediated increases in ALT strongly correlated with increases in taurolithocholic acid and taurodeoxycholic acid, the major secondary BAs in dog plasma, indicating a mechanistic link between ALT elevation and changes in BA pool hydrophobicity. Thus, CHO may offer the potential to mitigate elevations in serum aminotransferases in human subjects that are caused by targeted FGFR4 inhibition and elevated intracellular BA levels.