Mechanism-Based Biomarkers for Glucose-Lowering in TINSAL-T2D

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DESCRIPTION (provided by applicant): TINSAL-T2D is a multicenter, randomized, placebo-controlled, dose-ranging clinical trial designed to determine glycemic efficacy, safety and tolerability of salsalate in patients with T2D. The trial was divided into two stages. Stage 1, having a 14-week treatment period comparing 3 doses of salsalate vs. placebo, has been completed; stage 2, which is ongoing, compares a single dose of salsalate to placebo for 48 weeks of exposure. The results of stage 1 demonstrated HbA1c lowering as well as improvements in other parameters of glycemic control. Triglyceride levels were also reduced and adiponectin levels increased, suggesting potential cardioprotection. The results from stage 1 of TINSAL-T2D thus support the potential use of this simple anti-inflammatory drug with a long-term established safety profile in patients with T2D. Despite the rapid and promising progress in establishing clinical efficacy, parallel progress to discover mechanisms of action for salsalate's glucose- and lipid-lowering and anti-inflammatory effects and potential side effects has lagged. Rationale. We have found that salicylic acid (SA), the active form of salsalate, simultaneously inhibits NF-:B and activates HSF-1 in cultured cells, rodent models, and patients with T2D. Both are transcription factors: NF-:B is a master regulator of inflammation while HSF-1 is a master regulator of stress responses. That salsalate upregulates one and down-regulates the other predicts antiparallel changes in the expression levels of transcriptional targets. This is readily apparent in cultured cells and tissues from treated animals and patients. That SA/salsalate affects the activities of two transcription factors further suggests that it could modulate other transcription factors. Because SA affects transcription, genome-wide expression profiling provides an ideal method for the global assessment of its effects. Research Plan: Blood samples for mRNA isolation (Paxgene) were collected during stage 1 of TINSAL-T2D, at baseline and after 14 weeks treatment (25-27 subjects each from placebo and 3 treatment groups). RNA will be isolated and used to determine genome-wide mRNA expression levels. Validated changes in leukocyte mRNA expression will be used as potential mechanism-based biomarkers that correlate with and predict efficacy and safety. These findings in conjunction with the results from additional response, pathway and network analyses will be used in attempts to identify responder subgroups and molecular mechanisms for efficacy and toxicity of salsalate in patients with T2D. PUBLIC HEALTH RELEVANCE: We have found that an old and safe drug (salicylate, salsalate) has a previously unrecognized capacity to lower blood glucose levels in patients with diabetes. Since clinical studies have progressed rapidly and the drug may be approved for use in patients, is important to know how it works in greater detail. Proposed studies provide biomarkers that correlate with and potentially predict efficacy and safety, and may help to identify mechanisms of action.