Successful integration of nonclinical and clinical findings in interpreting the clinical relevance of rodent neoplasia with a new chemical entity

Sodium-Glucose Co-Transporter Protein 2 Inhibitors Induced Hypercalcemia: A Case Series and Literature Review

Background

Sodium-glucose co-transporter protein 2 (SGLT2) inhibitors are the newest class of oral antihyperglycemic agents. To our knowledge, hypercalcemia has not been labeled as a side effect of this class; nevertheless, 2 cases have been reported over the last few years.

Case Report

We present a case series of 3 patients with type 2 diabetes mellitus (T2DM) in whom hypercalcemia developed when they were started on canagliflozin and dapagliflozin treatment. In cases 1 and 2, hypercalcemia developed shortly after increasing the canagliflozin dose. In both cases, calcium levels returned to the normal range 1 week after discontinuing canagliflozin treatment. In case 3, laboratory workup revealed an elevated serum calcium level shortly after switching the therapy to dapagliflozin.

Discussion

The first reported case of hypercalcemia related to SGLT2 inhibitor use was described in relation to canagliflozin. High calcium level was also reported in a patient after introducing dapagliflozin. In our cases, hypercalcemia was first noted after increasing the dose of canagliflozin and after introducing dapagliflozin. Although the exact causes are unknown, we propose a comprehensive multifactorial mechanism.

Conclusion

This is the first reported case series of hypercalcemia associated with SGLT2 inhibitors. Although the exact mechanisms remain uncertain, these drugs may predispose individuals to hypercalcemia. Monitoring for signs and symptoms of hypercalcemia or better switching to more selective SGLT2 inhibitors in at-risk patients could potentially prevent this complication.

Peripheral Artery Disease in Diabetes Mellitus: Focus on Novel Treatment Options

Diabetes mellitus (DM) and peripheral artery disease (PAD) are two clinical entities closely associated. They share many pathophysiological pathways such as inflammation, endothelial dysfunction, oxidative stress and pro-coagulative unbalance. Emerging data focusing on agents targeting these pathways may be promising. Moreover, due to the increased cardiovascular risk, there is a growing interest in cardiovascular and "pleiotropic" effects of novel glucose lowering drugs. This review summarizes the main clinical features of PAD in patients, the diagnostic process and current medical/interventional approaches, ranging from "classical treatment" to novel agents.

Mechanisms of Rodent Renal Carcinogenesis Revisited

The important renal tumors that can be induced by exposure of rats to chemical carcinogens are renal tubule tumors (RTTs) derived from tubule epithelium; renal pelvic carcinoma derived from the urothelial lining of the pelvis; renal mesenchymal tumors (RMTs) derived from the interstitial connective tissue; and nephroblastoma derived from the metanephric primordia. However, almost all of our knowledge concerning mechanisms of renal carcinogenesis in the rodent pertains to the adenomas and carcinomas originating from renal tubule epithelium. Currently, nine mechanistic pathways can be identified in either the rat or mouse following chemical exposure. These include direct DNA reactivity, indirect DNA reactivity through free radical formation, multiphase bioactivation involving glutathione conjugation, mitotic disruption, sustained cell proliferation from direct cytotoxicity, sustained cell proliferation by disruption of a physiologic process (alpha 2u-globulin nephropathy), exaggerated pharmacologic response, species-dominant metabolic pathway, and chemical exacerbation of chronic progressive nephropathy. Spontaneous occurrence of RTTs in the rat will be included since one example is a confounder for interpreting kidney tumor results in chemical carcinogenicity studies in rats.

Molecular Modulation of Osteoblasts and Osteoclasts in Type 2 Diabetes

Diabetes is a common disease affecting majority of populations worldwide. Since 1980, there has been an increase in the number of people diagnosed as prediabetic and diabetic. Diabetes is characterized by high levels of circulating glucose and leads to most microvascular and macrovascular complications such as retinopathy, nephropathy, neuropathy, stroke, and myocardial infarction. Bone marrow vascular disruption and increased adiposity are also linked to various complications in type II diabetes mellitus. In addition to these complications, type 2 diabetic patients also have fragile bones caused by faulty mineralization mainly due to increased adiposity among diabetic patients that affects both osteoblast and osteoclast functions. Other factors that increase fracture risk in diabetic patients are increased oxidative stress, inflammation, and drugs administered to diabetic patients. This review reports the modulation of different pathways that affect bone metabolism in diabetic conditions.

Renal tubular and adrenal medullary tumors in the 2-year rat study with canagliflozin confirmed to be secondary to carbohydrate (glucose) malabsorption in the 15-month mechanistic rat study

During preclinical development of canagliflozin, an SGLT2 inhibitor, treatment-related pheochromocytomas, renal tubular tumors (RTT), and testicular Leydig cell tumors were reported in the 2-year rat toxicology study. In a previous 6-month rat mechanistic study, feeding a glucose free diet prevented canagliflozin effects on carbohydrate malabsorption as well as the increase in cell proliferation in adrenal medulla and kidneys, implicating carbohydrate malabsorption as the mechanism for tumor formation. In this chronic study male Sprague-Dawley rats were dosed orally with canagliflozin at high dose-levels (65 or 100 mg/kg/day) for 15 months and received either a standard diet or a glucose-free diet. Canagliflozin-dosed rats on standard diet showed presence of basophilic renal tubular tumors (6/90) and an increased incidence of adrenal medullary hyperplasia (35/90), which was fully prevented by feeding a glucose-free diet (no RTT's; adrenal medullary hyperplasia in ≤5/90). These data further confirm that kidney and adrenal medullary tumors in the 2-year rat study were secondary to carbohydrate (glucose) malabsorption and were not due to a direct effect of canagliflozin on these target tissues.

Diabetes Drug Effects on the Skeleton

Diabetes be it type 1 or type 2 is associated with an increased risk of fragility fractures. The mechanisms underlying this increased risk are just being elucidated. Anti-diabetes medications are crucial for maintaining glucose control and for preventing micro- and macrovascular complications in diabetes. However, they may modulate fracture risk in diabetes in different ways. Thiazolidinediones have demonstrated an unfavorable effect on the skeleton, while metformin and sulfonylureas may have a neutral if not beneficial effect on bone. The use of insulin has been associated with an increased risk of fragility fractures though it is not clear whether it is due to direct influence of insulin or whether it is mediated through hypoglycemia and increased falls risk. The overall effect of incretin mimetics appears to be beneficial; however, this has to be elucidated further. The bone effects of pramlintide, a synthetic analog of amylin, have not been explored fully. Finally, issues regarding bone safety of SGLT2 (sodium-dependent glucose transporter 2) inhibitors, the newest anti-diabetic medications on the market are of concern. The purpose of this review is to provide a comprehensive overview of the effect of these medications on bone metabolism and the studies exploring the risk or lack thereof of these medications on bone loss and fragility fractures.

The effects of canagliflozin, a sodium glucose co-transporter 2 inhibitor, on mineral metabolism and bone in patients with type 2 diabetes mellitus

BACKGROUND

Sodium glucose co-transporter 2 (SGLT2) inhibitors lower blood glucose levels in patients with type 2 diabetes mellitus (T2DM) by increasing urinary glucose excretion. This review provides a comprehensive summary of preclinical and clinical data on the effects of the SGLT2 inhibitor canagliflozin on mineral balance and bone.

METHODS

Published articles and internal study reports through November 2015 were included.

RESULTS

In clinical studies, canagliflozin was not associated with meaningful changes in serum or urine calcium, parathyroid hormone, or vitamin D. Canagliflozin was associated with increases in serum magnesium and phosphate without changes in their urinary excretion. Increases in serum collagen type-1 beta-carboxy-telopeptide (beta-CTX), a bone resorption marker, and osteocalcin, a bone formation marker, were observed with canagliflozin. Decreases in total hip bone mineral density (BMD) of up to 1.2% were seen with canagliflozin after 2 years; no changes in BMD were seen at other skeletal sites. Changes in total hip BMD and serum beta-CTX with canagliflozin correlated with decreases in body weight. In a clinical program-wide analysis, canagliflozin was associated with increased fracture risk that was driven by a higher incidence in the cardiovascular safety study (CANVAS), with no fracture imbalance seen in pooled data from other Phase 3 studies. The fracture imbalance occurred within 12 weeks after initiating treatment, most frequently in the distal portion of the upper and lower extremities.

CONCLUSIONS

Across clinical studies, canagliflozin did not meaningfully affect calcium homeostasis or hormones regulating calcium homeostasis. Increases in bone turnover markers and decreases in BMD at the total hip, but not at other sites, that correlated with weight loss were seen with canagliflozin. Canagliflozin was associated with a higher fracture incidence within 12 weeks, primarily in distal extremities. Data from ongoing canagliflozin studies will provide additional information on fracture risk.

Evaluation of Bone Mineral Density and Bone Biomarkers in Patients With Type 2 Diabetes Treated With Canagliflozin

CONTEXT

Canagliflozin is a sodium glucose cotransporter 2 inhibitor developed to treat type 2 diabetes mellitus (T2DM).

OBJECTIVE

Our objective is to describe the effects of canagliflozin on bone mineral density (BMD) and bone biomarkers in patients with T2DM.

DESIGN

This was a randomized study, consisting of a 26-week, double-blind, placebo-controlled period and a 78-week, double-blind, placebo-controlled extension.

SETTING

This study was undertaken in 90 centers in 17 countries.

PATIENTS

Patients were aged 55-80 years (N = 716) and whose T2DM was inadequately controlled on a stable antihyperglycemic regimen.

INTERVENTIONS

Canagliflozin 100 or 300 mg or placebo were administered once daily.

OUTCOME AND MEASURES

BMD was assessed using dual-energy x-ray absorptiometry at weeks 26, 52, and 104. Bone strength was assessed using quantitative computed tomography and finite element analysis at week 52. Serum collagen type 1 β-carboxy-telopeptide, osteocalcin, and estradiol were assessed at weeks 26 and 52.

RESULTS

Canagliflozin doses of 100 and 300 mg were associated with a decrease in total hip BMD over 104 weeks, (placebo-subtracted changes: -0.9% and -1.2%, respectively), but not at other sites measured (femoral neck, lumbar spine, or distal forearm). No meaningful changes in bone strength were observed. At week 52, canagliflozin was associated with an increase in collagen type 1 β-carboxy-telopeptide that was significantly correlated with a reduction in body weight, an increase in osteocalcin, and, in women, a decrease in estradiol.

CONCLUSIONS

In older patients with T2DM, canagliflozin showed small but significant reductions in total hip BMD and increases in bone formation and resorption biomarkers, due at least in part to weight loss.