Type 2 diabetes (T2D) is a devastating disease that has undergone a striking increase in prevalence in the U.S. and worldwide. Although a number of different drugs exist to help manage this condition, unfortunately more than 1/3 of affected individuals fail to achieve healthy blood glucose levels. Of the therapies used, metformin (i.e. Glucophage, a member of the biguanide drug class) is the most prominent of the drugs as measured by the number of prescriptions issued worldwide. Unfortunately however, up to 10% of potential patients cannot tolerate this agent because of gastrointestinal adverse effects while another, even larger, segment of the diabetic population with renal insufficiency cannot take metformin because of the risk of lactic acidosis, a life-threatening condition caused by a decrease in metformin elimination by the kidney. In the current revised application, a research plan is proposed to identify novel biguanides that can treat the segment of T2D subjects who are unable to take metformin or respond poorly to this drug. The plan is based on the transport of biguanides into liver and kidney cells by OCT1 and OCT2, respectively. In this approach, new biguanides will be synthesized by NovaTarg chemistry to increase their affinity for OCT1 while reducing their affinity for OCT2. We anticipate an increase in efficacy from the increase in uptake by the liver (OCT1), the target tissue of biguanides. Whereas a decrease in metformin elimination via the kidney (OCT2) is expected to make drug exposure predictable even in patients with impaired renal function. Thus, by changing the elimination pattern, the new biguanides will have the potential to be used by T2D subjects with renal insufficiency. The recent discovery that a third OCT, OCT3, acts to transport metformin into skeletal muscle has enlarged the scope of this work. In this revised application the novel biguanides will be tested for their activity on OCT3 and their ability to activate muscle AMPK. Although liver remains our primary focus on efficacy, compounds that can act on both liver and muscle should augment the control of blood glucose in T2D patients. As pointed out in our preliminary data, a chemistry plan is in place that has shown its ability to generate biguanides with improved selectivity for OCT1 over OCT2 when compared to metformin. Importantly in preliminary results, certain of these new biguanides have demonstrated an ability to activate AMPK in liver and muscle cells, to reduce hepatic cell glucose output, and to accelerate glucose disposal in mice as measure by an OGTT (see data for NT1014). These encouraging results argue for a successful outcome (i.e. a markedly improved metformin, both in efficacy and safety) in a drug class that has not experienced any significant innovation in over 40 years.
Worldwide the prevalence of diabetes among adults is about 6.4% and is estimated to increase to 7.7% by 2030, representing 439 million adults, resulting in expenditures of approximately 1 in 5 healthcare dollars on diabetes-related care in the US. Despite the recent introduction of new classes of treatments for type 2 diabetes (T2D), the availability of effective medicines is still limited by safety and efficacy;two-thirds of patients receiving medication for T2D in Europe and the US still do not achieve their therapeutic goals. In this revised application we describe the discovery of liver selective biguanides that activate AMPK in target cells and, by avoiding renal elimination, have the potential to be more efficacious than metformin, with an improved PK profile and that would be safe to use in all diabetic patients, including those with renal insufficiency.
| Arner, Peter; Kulyté, Agné; Batchelor, Kenneth et al. (2018) Mapping of biguanide transporters in human fat cells and their impact on lipolysis. Diabetes Obes Metab 20:2416-2425 |
