Download pdf - Differentiating sodium-glucose co-transporter-2 inhibitors in development for the treatment of type 2 diabetes mellitus

1. Introduction

2. Role of the kidney in glucose

homeostasis

3. SGLTs -- characterization and

expression

4. Development of

SGLT2 inhibitors

5. Potency and selectivity

6. Data from animal models

7. Comparison of pharmacology

profile of SGLT2 inhibitors

and knockout animal models

8. Clinical studies

9. Safety

10. Conclusions

11. Expert opinion

Review

Differentiating sodium-glucoseco-transporter-2 inhibitors indevelopment for the treatmentof type 2 diabetes mellitusWilliam N Washburn† & Simon M Poucher†Metabolic Disease Chemistry, Research and Development, Bristol-Myers-Squibb Co.,

Princeton, NJ, USA

Introduction: Sodium-glucose co-transporter-2 (SGLT2) inhibitors are a novel

class of agents for the treatment of type 2 diabetes mellitus (T2DM). By inhib-

iting SGLT2, they prevent renal glucose reabsorption, resulting in glucosuria.

Areas covered: The rationale for development of SGLT2 inhibitors is reviewed,

with particular focus on the nine SGLT2 inhibitors currently in development.

The authors compare the potency and SGLT2 selectivity of the agents, as

well as the results from both animal and clinical studies, considering the

potential implications they may have for clinical use.

Expert opinion: Current evidence suggests that SGLT2 inhibitors have similar

efficacy in terms of glycemic control and also demonstrate benefits beyond gly-

cemic reductions, including reductions in body weight and modest reductions

in blood pressure. Additionally, they appear to preserve beta-cell function

and improve insulin sensitivity. Their mechanism of action allows for combina-

tion of SGLT2 inhibitors with other antidiabetic drugs and use across the treat-

ment continuum for T2DM. Potential differences in safety and efficacy based on

observed differences in potency and selectivity among the SGLT2 inhibitors,

particularly versus SGLT1, remain to be seen. Further long-term data, including

post-marketing surveillance, are required to fully determine the safety profile

of SGLT2 inhibitors in large patient groups.

Keywords: dapagliflozin, glucosuria, SGLT2, sodium-glucose co-transporter-2 inhibitors,

type 2 diabetes mellitus

Expert Opin. Investig. Drugs (2013) 22(4):463-486

1. Introduction

The number of people with type 2 diabetes mellitus (T2DM) approximated366 million in 2011 and is expected to rise to 552 million by 2030 [1]. Complica-tions of diabetes are mostly macrovascular and microvascular and frequently lead tomorbidity and early mortality.

There is an unmet medical need for better agents to treat T2DM as the propor-tion of patients achieving target goals remains unsatisfactory; HbA1c levels < 7% arenot achieved in ~ 40% of patients [2,3]. Over the past 5 years, a new class of agents,sodium-glucose co-transporter-2 (SGLT2) inhibitors, has emerged as an excitingopportunity for the treatment of these patients. SGLT2 inhibitors have a completelydifferent mechanism of action from other antidiabetic agents, which is independentof the actions of insulin [4]. Thus, we may postulate that SGLT2 inhibitors shouldnot fail over time, unlike many other antidiabetic drugs, since the progressive loss ofbeta cells should not have a direct effect on efficacy. In addition to offering anadvance in the options available, these agents are also complementary to coadmi-nistration with existing agents [4]. This review assesses the rationale for

10.1517/13543784.2013.774372 © 2013 Informa UK, Ltd. ISSN 1354-3784, e-ISSN 1744-7658 463All rights reserved: reproduction in whole or in part not permitted

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SGLT2 inhibition and the profile of agents currently in devel-opment, in order to determine whether there is a factor thatmight distinguish one agent from the group.

2. Role of the kidney in glucose homeostasis

The kidney contributes to glucose homeostasis in healthy sub-jects by reabsorbing an estimated 180 g of filtered glucose daily(Figure 1A) [5,6]. Reabsorption of glucose is mediated by SGLTsin the lumen-facing apical membranes of epithelial cells,within the proximal tubule. The capacity of the kidney to reab-sorb glucose through these transporters becomes saturatedwhen filtered glucose concentrations exceed 200 mg/dl, asoccurs in patients with uncontrolled T2DM (Figure 1B) [5,6].Under these conditions, filtered glucose in excess of themaximum capacity is excreted in urine [5,7]. Although renalreabsorption capacity is not normally exceeded in healthy indi-viduals, rare exceptions of glucosuria can be found in nondia-betic individuals with familial renal glucosuria who have amutated SGLT2 gene. These individuals experience urinaryglucose excretion (UGE) due to loss of SGLT2-mediated renalglucose reabsorption and are otherwise asymptomatic [8,9].

3. SGLTs -- characterization and expression

Renal microperfusion studies demonstrated that there are twodifferent functional SGLTs in the kidney, namely SGLT1 and

SGLT2. The early part of the proximal tubule expresses alower affinity (Km 1.6 mM) transporter than the late proximaltubule (Km 0.35 mM), yet, has a capacity for glucose reabsorp-tion that is 10-fold greater that in the late tubule [10]. Studiesin brush border membrane vesicles from human and rabbitkidney cortex also support the presence of two SGLTs. Thelow-affinity transporter SGLT2, with a Km of ~ 6 mM, hada 1:1 sodium:glucose stochiometry, while the high-affinitytransporter SGLT1 had a 2:1 stochiometry [11-14]. Biochemicalparameters of SGLTs are summarized in Table 1 [15,16].

SGLT1 protein has been mapped to the brush border mem-brane of the S3 proximal tubule within the cortex and theouter stripe of the rat kidney [17]. Recently SGLT2, but notSGLT1, mRNA was found in the brush border membrane ofthe S1 and S2 segments (S1 > S2) in rats and mice [18]. Westernblots from a range of mouse tissues showed SGLT2 in the kid-ney only. The very weak bands found in the brain and eyes didnot correspond to SGLT2. Furthermore, using SGLT2-specific primers for exons 6 -- 7 and exon 13 showed virtuallyexclusive expression in the kidney cortex compared with71 other tissues of normal individuals [19]. However, therehave been reports of a broader SGLT2 expression profile,including in the brain [20,21]. The discrepancy seems to havebeen resolved in that the primer/probe sequences used in thebroader expression reports overlapped with the extreme 3’end of another gene (C16orf58), which is encoded on theopposite strand and is more ubiquitously expressed thanSGLT2 [19].

The only other SGLT expressed predominantly in both themedulla and cortex of the kidney is SGLT5 (55% homologywith SGLT2). Of the other SGLT family members, onlyhuman sodiummyoinositol transporter (SMIT; 45% homologywith SGLT2) is expressed in the renal medulla. Sodium-dependent amino acid transporter (SAAT1; 57% homology)and SGLT4 (58% homology) are expressed mainly in the gut,while SGLT6 (49% homology) is expressed in the brain, gutand spinal cord. SGLT1 expression is highest in the gut [19].

SGLT2 expression is increased in human exfoliated prox-imal tubular epithelial cells in patients with T2DM [22].Consequently, in T2DM, renal glucose reabsorption capac-ity is enhanced, further altering the imbalance betweenreabsorption and excretion [23]. Studies in Wistar rats withchemically induced diabetes also show a 36 -- 60% increasein renal SGLT2 expression and a 37% increase in glucoseuptake in brush border membrane vesicles [24-27]. The Km

for glucose was unaltered but maximum velocity increasedby 58% [26], supporting increased protein expression inhyperglycemia. In obese Zucker rats, SGLT1 and SGLT2expression were increased by as much as fourfold at21 weeks [28]. Another study revealed that 2 h exposure ofHEK 293 cells to insulin increased hSGLT2, but nothSGLT1 activity, concentration-dependently [29]. Since noinformation about media glucose concentration was given,it is not possible to determine if glucose might play a per-missive role in translocation of the SGLT2 protein. It

Article highlights.

. The kidney plays a central role in glucose homeostasisthrough the reabsorption of filtered glucose, mediatedby glucose transporters, such as the SGLTs. In T2DMpatients, renal glucose reabsorption continuesdespite hyperglycemia.

. SGLT2 is expressed almost exclusively in the kidney andis responsible for the majority of reabsorption offiltered glucose.

. Nine SGLT2 inhibitors in clinical development differ intheir potency and selectivity for SGLT2.

. SGLT2 inhibitors are being investigated across thespectrum of T2DM, as monotherapy or in combinationwith other antidiabetic agents. Each has illustratedefficacy in terms of glycemic control, as well as otherbenefits, including modest weight and BP reductionsand a low propensity to cause hypoglycemia.

. Observations in animal models suggest thatSGLT2 inhibitors may reduce glucotoxicity enablingimprovements in insulin sensitivity and secretion. Thishas been supported by initial results in T2DM patientstreated with dapagliflozin.

. AEs are consistent with those expected based on themechanism of action, namely increases in genitalinfections and UTIs. The majority of AEs are mild andcan be treated with standard treatment. Long-termexperience is required to fully understand the safetyprofiles of these agents.

This box summarizes key points contained in the article.

W. N. Washburn & S. M. Poucher

464 Expert Opin. Investig. Drugs (2013) 22(4)

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appears that, although insulin may be responsible for thediurnal changes in SGLT2 activity in the proximal tubule,hyperglycemia is responsible for the longer-term overex-pression that exacerbates plasma glucose concentration inpatients with T2DM.

To understand the impact of SGLT2 inhibition on renalglucose transporter expression, RNA transcription profilinganalyses of obese, male ZDF rats dosed orally for 5 weekswith dapagliflozin was undertaken [30]. In the kidney, onlySGLT5 expression was altered by dapagliflozin under fastedconditions (66% increase; p < 0.03); SGLT2 and SGLT1expression levels were unchanged. Renal GLUT2 gene expres-sion was reduced by 40% (p < 0.005) [30]. It is thereforeunlikely that compensatory increases in SGLT2 proteinexpression might lead to tachyphylaxis.

4. Development of SGLT2 inhibitors

4.1 O-glucosidesThe O-glucoside natural product phlorizin 1 was the firstSGLT2 inhibitor [31]. Phlorizin lowered serum glucose whenadministered to a patient with diabetes > 100 years ago [32].Although phlorizin is competitive, it is a nonselective inhibitorof SGLT1 and SGLT2. It, therefore, blocks intestinal glucose-galactose absorption (an SGLT1-mediated effect) as well as renalglucose reabsorption. Phlorizin also has poor bioavailability dueto rapid hydrolysis by lactase-phlorizin hydrolase. Despite theselimitations, interest in SGLT inhibition was renewed in the late1980s when Rossetti et al. demonstrated that phlorizin-inducedUGE reduced hyperglycemia in partial pancreatectomized ratsthrough increased insulin secretion [33] and normalized insulin

A.

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Low affinity, high capacity High affinity, low capacity

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Reab sorbedTm =

375 mg/min

Figure 1. Role of the kidney in glucose homeostasis. The kidney has a central role in the reabsorption of filtered glucose in

healthy subjects (A). When glucose concentrations exceed 200 mg/dl, the kidney is unable to reabsorb any further glucose and

excess glucose is excreted in the urine (B).Graph in Figure 1B adapted with permission from Silverman & Turner 1992 [138].

Differentiating SGLT2 inhibitors in development for the treatment of T2DM

Expert Opin. Investig. Drugs (2013) 22(4) 465

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sensitivity through reduced glucotoxicity [34]. Insulin sensitivityand glycemic control benefits following phlorizin were tran-sient and were lost within 2 weeks of treatment cessation.All subsequent SGLT2 inhibitors are modifications of the

phlorizin pharmacophore. Modification of the aglycone moi-ety, thereby, increasing lipophilicity while maintaining thebeta O-glucoside bond generated more drug-like candidatesexemplified by T-1095A (2) [35]. The discovery that thethree-atom linker joining the two aryl rings of phlorizin andcompound 2 could be replaced with a single bridging atomled to remogliflozin (3) and subsequently sergliflozin A (4;Figure 2) [36]. All three O-glucosides 2 -- 4 exhibited threefoldto fivefold greater potency and 20-fold greater SGLT1 selec-tivity than phlorizin. Unknown at the time, utilization of thefive-membered pyrazole ring as the planar central aryl ring ofcompound 3 increased affinity for SGLT5 to such an extentthat compound 3 became only 20-fold selective againstSGLT5. However, for all these O-glucosides, the susceptibilityof the O-glycosidic bond to glucosidase-mediated hydrolysisprior to absorption from the gastrointestinal tract necessitatedadministration as alkyl carbonate prodrug esters and contributedto rapid clearance following conversion to the active agent.

4.2 C-glucosidesReplacement of the initial O-glucoside-containing SGLT2inhibitors with the more metabolically robust C-glucosidesbecame feasible following the discovery that a different spatialpresentation was required. Deletion of the anomeric oxygenof glucose in conjunction with a shift of the point of attach-ment of the sugar relative to the benzyl moiety of compound 4

from 1,2 (ortho) to 1,3 (meta) generated potent selectiveSGLT2 inhibitors exemplified first by dapagliflozin (5) [37].This structural modification increased SGLT2 affinityby ~ 10-fold and SGLT1 selectivity by around two- to three-fold. Additionally, since C-glucoside-based inhibitors lack thehydrolytic susceptibility of O-glucosides, the need for a prodrugwas obviated. The diarylmethane pharmacophore of com-pound 5 has been subsequently modified yielding eight addi-tional compounds: canagliflozin (6; Johnson & Johnson/Tanabe), ipragliflozin (7; Astellas), empagliflozin (8; Boehringer

Ingelheim/Eli Lilly), luseogliflozin (9; Taisho), tofogliflozin (10;Chugai), ertugliflozin (11; Pfizer), LX4211 (12; Lexicon) andEGT-1442 (13; Theracos; Figure 3) [38].

5. Potency and selectivity

Compared with the O-glucosides 1 -- 4, SGLT2 potency forthe nine C-glucosides was enhanced, with half maximal effec-tive concentration (EC50) values ranging from 1 to 5 nM(Tables 2 and 3). The distinguishing factor for these nine clin-ical candidates was the selectivity exhibited versus other SGLTtransporters. Due to concerns regarding the potential for gas-trointestinal disturbances, most groups sought high selectivityversus SGLT1. With respect to selectivity versus SGLT1, theset was divided into three groups: weakly selective, consistingof LX4211 (20-fold); moderate, comprising canagliflozin andipragliflozin (~ 250- to 500-fold); and the remainder, com-prising dapagliflozin, empagliflozin, luseogliflozin, tofogliflo-zin and ertugliflozin, being very selective (‡ 1,000-fold).

Compounds 2 -- 11 differ with respect to selectivity versusSGLT3, SGLT4, SGLT5 and SGLT6 (Tables 2 and 3). Allthe C-glucosides 5 -- 11 exhibited high selectivity versusSGLT3 and SGLT4, whereas the selectivity versus SGLT4for the O-glucosides 1 -- 4 was uniformly 10-fold less. Selectiv-ity versus SGLT5 is 100- to 500-fold for all glucosides 2 -- 11apart from two outliers: remogliflozin (16-fold) and ertugliflo-zin (3400-fold). Only canagliflozin and luseogliflozin exhibitedas low as 200-fold selectivity versus SGLT6; the remaininginhibitors for which data were available were fivefold moreselective. Overall, ertugliflozin appears to be the most selectiveSGLT2 inhibitor.

More important than the inherent in vitro selectivity pro-files are the selectivity profiles experienced in clinical studiesat the doses required for efficacy as antidiabetic agents. Peakglomerular filtrate concentrations of inhibitors 3 -- 13 shouldbe minimally equal to serum levels of inhibitor not protein-bound or maximum observed plasma concentration valuesof free drug concentrations (although any further concentra-tion of the glomerular filtrate or reabsorption of inhibitorwhile traversing the proximal tubule is not taken into

Table 1. Biochemical characterization of the SGLT family [15,16].

Common name SGLT2 SGLT1 SMIT SGLT4 SGLT5 SGLT6

System name SLC5A2 SLC5A1 SLC5A3 SLC5A9 SLC5A10 SLC5A11Substrate Glucose, Galactose Glucose, Galactose Myo-inositol,

GlucoseGlucose, Mannose Unknown Myo-inositol,

GlucoseSubstrateevaluated

a-methyl-D-glucopyranoside

a-methyl-D-glucopyranoside

Myoinositol a-methyl-D-glucopyranoside

Mannose Myoinositol

SubstrateKm (mM)

2.6 ± 0.5 6.4 ± 1.3 0.08 ± 0.01 1.2 ± 0.21.6 ± 0.2

0.09 ± 0.01

DapagliflozinKi (µM)

0.00055 ± 0.00016 0.81 ± 0.2 14 ± 2 3.3 ± 0.7 0.82 0.80 ± 0.1

Phlorizin Ki (µM) 0.05 ± 0.005* 0.164 ± 0.01 150 ± 40 5.5 ± 0.9 13 ± 0.5

Ki: Inhibition constant (the concentration required to produce half maximum inhibition); Km: Concentration at half the maximum velocity.



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account). For this analysis, if the free concentration was calcu-lated to exceed 50% of the EC50 for the off-target SGLT,inhibition was predicted; if the free concentration exceeds20% of the EC50, inhibition was judged to be possible. Bythis analysis, assuming the percentage free drug is comparableto the 5% observed for dapagliflozin, the renal pharmacologicresponse produced by dapagliflozin, empagliflozin, luseogli-flozin and ertugliflozin is predicted to be solely mediated bySGLT2. In contrast, remogliflozin should significantly inhibitSGLT5 and possibly SGLT4; ipragliflozin would be expectedto inhibit SGLT5 and possibly SGLT1. Canagliflozin shouldalso inhibit SGLT6 and possibly SGLT5 and SGLT1.LX4211 is predicted to significantly inhibit SGLT1.

6. Data from animal models

The robust glucosuric response following administration ofinhibitors 2 -- 13 to diabetic rodent models was encouraging.Studies with db/db mice revealed that 6 weeks’ treatmentwith tofogliflozin prevented beta-cell failure and preservedinsulin secretion capability [39]. Studies with young ZDF ratsrevealed that canagliflozin improved hepatic glucose metabo-lism by a beneficial effect on glucokinase expression [40].ZDF rats treated with dapagliflozin for 5 weeks exhibited thegreatest elevation of hepatic steroyl coenzyme A desaturase(+3000%) and glucokinase (+270%) gene expression anddecrease in 11-b hydroxysteroid dehydrogenase (-70%) [30];hepatic glucose production was reduced; total glucose infusionrate was increased but uptake in skeletal muscle and epididy-mal fat was unchanged [41]. Treatment of db/db mice with10 mg/kg of luseogliflozin for 10 weeks decreased fed-glucose levels by two-thirds without changing insulin levels,decreased pancreatic a-cell mass by 40% and increased b-cellmass by ~ 40% [42].

Chugai reported that the risk of hypoglycemia was virtuallyabolished for highly selective SGLT2 inhibitors, as hepaticglucose output could compensate for the SGLT2-mediatedurinary loss. In contrast, complete compensation was notachieved for weakly selective SGLT2 inhibitors due to theadditional glucosuria arising from significant SGLT1 inhi-bition, suggesting that these agents potentially posed a greaterhypoglycemic risk [43]. Glucose infusion studies with ZDFrats administered 1 mg/kg of canagliflozin prior to beingrendered hypoglycemic revealed that the renal glucose thresh-old was maintained, albeit shifted leftward from 400 to94 mg/dL, thereby, bolstering the expectation that selectiveSGLT2 inhibitors pose a minimal hypoglycemic risk [44].Glucose fluxes in ZDF rats promoted by one dose of dapa-gliflozin indicated that endogenous glucose productionwas increased to defend a normoglycemic rather than ahyperglycemic state [45].

Additional insights demonstrated further benefits ofSGLT2 inhibition. Four weeks of administration of ipragli-flozin to KK-Ay mice at 0.1 and 1 mg/kg significantlyreduced progression of diabetic nephropathy as inferred bythe decrease in urinary albumin versus control [46]. Ertugliflo-zin at 6 mg/kg induced sufficient UGE in spontaneouslyhypertensive rats so that after 25 days the diuretic effectreduced blood pressure (BP) comparable to that achievedwith the loop diuretic furosemide [47].

Several groups have assessed the weight change indietary-induced obese rats when administered SGLT2 inhi-bitors for 28 days. Administration of empagliflozin, luseogliflo-zin and dapaglilfozin resulted in weight reductions versuscontrol [48-50]. Even under ad lib feeding, weight reductiondue to loss of primarily adipose tissue occurs since the increasedcaloric consumption only partially (60%) compensates for thecalories lost to glucosuria [50].

7. Comparison of pharmacology profile ofSGLT2 inhibitors and knockout animal models

Two mouse models of SGLT2 function loss have beendescribed [51-53]. One was generated as a targeted exondeletion within the SGLT2 gene (SGLT2 knockout [KO])and the other by ethylnitrosourea mutagenesis to produce aframeshift mutation within the gene (Sweet Pee). Bothmodels display normoglycemic glucosuria, showing reducedglucose levels in KO versus non-KO (Table 4). In Sweet Pee,a reduced lifespan was noted only in diabetic mice. Althoughnot specifically evaluated, reduced lifespan was not observedin the KO model. Other model differences, including thegenetic background and degree of hyperglycemia, may havecontributed to the difference noted for the occurrence ofinfections (observed in diabetic Sweet Pee mice but not inthe db/db cross KO mice [52]). This difference may relateto the different background strain or degree of diabetesin these two models, but infections are not inherentto glucosuria.

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1 Phlorizin 2a T1095A R = H2b T1095 R = H3COC(=O)

3a R = H Remogliflozin3b R = (O=)COEt

4a R = H Sergliflozin A4b R = (O=)COEt Sergliflozin

Figure 2. O-glucoside containing SGLT2 inhibitors.



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The SGLT2 KO metabolic phenotype on the normalmouse background consists of glucosuria [53], improved glu-cose tolerance following glucose challenge and increasedfood and water consumption. When bred into the diabeticdb/db mouse background, the KO mice displayed lower gly-cemic levels and improved islet function [51]. The KO renalphenotype displayed reduced proximal tubule reabsorptionof glucose and no significant changes in electrolyte excretionor glomerular filtration rate (GFR) [53]. Studies in diabeticrats suggest that when plasma glucose levels are held constant,no GFR change is observed with dapagliflozin treatment.However, when glycemia in diabetic rats is reduced withdapagliflozin, reductions in GFR can be observed consistentwith the effect of tubular glomerular feedback and restorationof electrolyte flow to the macula densa [53].In Goto-Kakizaki rats treated for 8 weeks with the early

inhibitor T1095, glucose-stimulated insulin secretion (GSIS)in isolated islets was enhanced [54]. Similar pancreatic preserva-tion effects have been observed with the SGLT2 inhibitorsdapagliflozin and empagliflozin in the male ZDF rat and the

high-fat-fed female ZDF rats [41,55,56]. Improvements in pan-creatic insulin content and morphology were observed 48 hafter the final dapagliflozin dose and so cannot be attributedto acute compound effects. With empagliflozin, effects weresustainable for 8 weeks, well beyond the point where liraglutidelost b-cell preservation efficacy [55]. Additionally, studies inprediabetic, dapagliflozin-treated male ZDF rats showed thatbaseline fasting plasma insulin levels were maintained, and byweeks 4 and 5 the plasma insulin levels were elevated comparedwith vehicle-treated ZDF rats. Pancreatic insulin content, anindicator of b-cell mass improvement, was also elevated indapagliflozin-treated ZDF rats; moreover, the incrementalchange in insulin response to oral glucose challenge was greaterin dapagliflozin-treated rats than vehicle-treated rats [41]. Thesestudies suggest that once-daily dosing with an SGLT2 inhibitorprevents progression to the hyperglycemic state, maintainsplasma insulin levels and preserves pancreatic function andinsulin content [41]. Results of ZDF rat studies with dapagliflo-zin and SGLT2 KO mice [41,53,55,56] suggest that reduction inglucotoxicity improves b-cell function.

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8 Empagliflozin (BI 10773) 9 Luseogliflozin (TS-071)

11 Ertugliflozin (PF-04971729) 12 LX-4211 13 EGT-1442

Figure 3. C-glucoside containing SGLT2 inhibitors.



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Several studies evaluating the long-term effects of variousSGLT2 inhibitors in a number of different rodent models ofhyperglycemia are summarized in Tables 5 and 6. Similari-ties emerge in the observations of SGLT2 KO mice cross-bred with db/db mice to the chronic efficacy magnitudeand observations obtained with the SGLT2 inhibitors,such as dapagliflozin, canagliflozin, empagliflozin, ipragliflo-zin, and other SGLT2 selective inhibitors. In nondiabeticrodents, there is also a similar effect on the fractional reab-sorption of glucose by SGLT2 KO mice and dapagliflozin-treated rats. These findings from the KO studies suggestthat systemic exposure of the different inhibitors indisease models is sufficient to achieve maximum inhibitionof SGLT2.

SGLT1 KO mice show glucose-galactose malabsorptionsyndrome symptoms that are apparently abrogated by provi-ding a diet low in these carbohydrates [57]. Additionally, theacute peak incretins (GIP and GLP-1) and the subsequentinsulin responses to glucose challenge are severely reducedin SGLT1 KO mice. SGLT1 is coexpressed with the K-and L-cells in the gut [57,58]. In addition to expression inthe gut and S3 segment of the distal convoluted tubule,SGLT1 expression is detected in skeletal and ventricularmuscle, and in the trachea [19]. The potential long-term effi-cacy and safety profile of nonselective SGLT1/2 inhibitionremains to be determined. LX4211, which has only marginalselectivity for SGLT2 unlike other SGLT2 inhibitors indevelopment [59], increased GLP-1 response to oral glucosechallenge in insulin-resistant mice, an effect that is alsoenhanced by sitagliptin [60]. Clinical studies with LX4211show that there is also an enhanced incretin response as aresult of increased glucose delivery to the colon, where theL-cells are situated. No additional gut issues have beenreported with this agent, although studies have been relativelyshort-term and in healthy subjects [61].

8. Clinical studies

8.1 O-glucosides SGLT2 inhibitorsResults from short-term clinical studies are summarizedin Tables 7 -- 10. The 24-h UGE response provides animmediate picture integrating the extent of inhibition of renalglucose recovery, the renal filtration rate, blood glycemic leveland inherent potency of the inhibitor. The reduction in fast-ing plasma glucose (FPG) levels is a less useful parameter forshort studies, since it changes over the course of the study,reflecting both the immediate loss of glucose due to theenhanced glucosuria as well as progressive reduction in gluco-toxicity and improved glucose homeostasis. Changes in bodyweight over the first weeks of the study primarily reflect thediuretic effect of the SGLT2 inhibitor. Several months maybe required for reduction in body weight to primarily reflectthe impact of uncompensated calories lost due to glucosuria.

The single ascending dose (SAD) and multiple ascendingdose (MAD) studies with the O-glucosides sergliflozin andremogliflozin revealed the pharmacokinetic profile to be sub-optimal, in part because they were susceptible to O-glucosi-dase cleavage. The resulting short half-life (~ 1.3 h)effectively attenuated the efficacy of sergliflozin [62]. As aconsequence, daily administration of high q.d. or t.i.d. doseswas required to partially compensate for rapid clearance.For example, a very modest glucosuric response (24-hUGE < 25 g) in healthy volunteers was observed even afteradministration of sergliflozin at 500 mg t.i.d. [63].. In contrast,35 g of glucose was excreted following administration of‡ 150 mg q.d. of remogliflozin despite the in vitro potencybeing less than that of sergliflozin and the half-lives beingcomparable [64]. Several factors may contribute to thispharmacokinetic/pharmacodynamic disconnect, including:i) conversion of remogliflozin to an active metaboliteGSK27978, and ii) a slow off-rate and iii) the glucosuric

Table 2. Predicted off-target SGLT inhibition occurring in clinical trials of O-glucosides, extrapolated from in vitro

SGLT2 EC50 and selectivity versus hSGLT1-6.

SGLT2

inhibitor

SGLT2

EC50 (nM)

Selectivity versus Clinical exposure

SGLT1 SGLT3 SGLT4 SGLT5 SGLT6 Refs. Dose (mg) Cmax

(nM)

SLGTs potentially

impacted if 5%

free in serum

Refs.

Phlorizin (1) 352116

101411 1300

290490

7136

4761000

[89]

[16]

[43]

T-1095A (2) 4.46.6

6030

500 250 750 [16]

[43]

Remogliflozin (3) 1214

542365

125 16 517 [16]

[43]

100 b.i.d.1,000 q.d.

98014,000

SGLT5;possible SGLT4

[90]

Sergliflozin (4) 7.57.5

280280

800 147 1,900 [16]

[43]

500 q.d. 2,400 None [63]

EC50: Half maximal effective concentration; Cmax: Maximum observed plasma concentration.



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response of remogliflozin may have been augmented by inhibi-tion of SGLT5, a manitol transporter expressed in the kidney.Further development of these two inhibitors has ceased.

8.2 C-glucoside SGLT2 inhibitors8.2.1 SAD and MAD studiesResults for initial clinical studies of less than a month withseven C-glucosides conducted in healthy volunteers and

T2DM patients have been disclosed (Tables 8 -- 10). To date,no results have yet been released for tofogliflozin andEGT-1442. SAD and MAD studies with healthy volunteersproduced dose-dependent glucosuric responses, resulting inthe loss of 55 -- 65 g of glucose over 24 h post-dose for mostagents, although the UGE produced by luseogliflozin appearedto be somewhat greater and that induced by LX4211 appearedto be considerably less. The glucosuric response produced by

Table 4. Comparison of the characteristics of the SGLT2 KO and Sweet Pee mouse models [51-53].

Similarities Differences

Sweet Pee SGLT2 KO

Marked glucosuria ENU induced frameshift mutation Targeted exon 1 -- 5 deletion~ 4-fold increase in urine volume C3H/HeJ background C57/Bl6 backgroundReduced hyperglycemia vs WT indiabetic models

Absolute UGE = 445 mg/25 g BW/day Absolute UGE = 470 mg/25 g BW/day

Unaltered Na+ excretion STZ to induce hyperglycemia db/db cross to induce hyperglycemia~ 100% increase in fluid intake Hyperglycemia 290 mg/dl in WT Hyperglycemia 200 mg/dl in WTHct remains unaltered No change in basal plasma glucose Variable report on basal blood glucoseKidney weight remains unaltered Increased expression of variant neopeptide

mRNA in diabetic mutantNo SGLT2 mRNA expression

GFR unaltered Increased mortality post-STZ No mortality reports

BW: Body weight; ENU: Ethylnitrosourea; Hct: Hematocrit; STZ: Streptozotocin; UGE: Urinary glucose excretion; WT: Wild type.

Table 3. Predicted off-target SGLT inhibition occurring in clinical trials of C-glucosides, extrapolated from in vitro

SGLT2 EC50 and selectivity versus hSGLT1-6.

SGLT2

inhibitor

SGLT2

EC50 (nM)

Selectivity versus Clinical exposure

SGLT1 SGLT3 SGLT4 SGLT5 SGLT6 Refs. Dose

(mg)

Cmax

(nM)

SLGTs potentially

impacted if 5%

free in serum

Refs.

Dapagliflozin (5) 1.11.21.3

1,2001,200610 190,000

7,6003,000

680210

1,1001,300

[89]

[16]

[43]

525

167705

None [91]

Canagliflozin (6) 2.22.76.7

414260290 52,000

2,9002,800

630180

90200

[92]

[16]

[43]

100300 b.i.d.

1,7408,000

SGLT5 & SGLT6Possible SLGT1

[93]

Ipragliflozin (7) 7.45.32.8

260570860 7,700

3,0004,500

14087

1,4703,500

[94]

[16]

[43]

100300

3,2808,600

SGLT5;possible SGLT1

[95]

Empagliflozin (8) 3.13.6

2,7001,100 62,000

3,5002,200

350110

6501,100

[16]

[43]

1025

260690

None [96]

Luseogliflozin (9) 2.33.1

1,7701,600 8,100 9,800 280 220

[97]

[43]

12.55

123322710

None [98]

Tofogliflozin (10) 6.42.9

1,9002,900 19,000

2,2001,500

470540 6,200

[16]

[43]

Ertugliflozin (11) 0.91.4

2,3001,300 > 71,000 2,300 3,400 980

[99]

[43]

5 [100]

LX4211 (12) 1.8 20 [59] 150300

590 SGLT1 [101]

EGT-1442 (13) 2 2435 [102]

EC50: Half maximal effective concentration; Cmax: Maximum observed plasma concentration.



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Table

5.Compariso

nofthelong-term

effectsofSGLT

2inhibitors

onbloodparameters

withtheSGLT

2KO

mouse

phenotypein

insu

lin-resistant/

hyperglycemic

endpoints.

SGLT

2KO

mouse

[51]

Dapagliflozin

Canagliflozin

[44]

Empagliflozin

Ipragliflozin

[103]

Other

OGTTglucose

AUC

37%

#onHFD

60--76%

#inZDF

~66%

#inZDFratat

26days

[55]

~30%

#inZDFat

37days

[104]

55%

#indb/dbwith

BI38335

[105];23%

#in

db/db4days

after

4-w

eektofogliflozinin

db/db

OGTTinsulin

AUC

48%

#onHFD

30--82%

"inZDF

111%

"inZDFat

26days

[55]

FPG

38%

#indb/db

24--57%

#FPG

inZDF

at2weeks[106];35%

#free-fedPG

inHFFFZDF[56];71%

#in

ZDFat5weeks[41]

22--36%

#indb/db

26--39%

#inmale

ZDF[104]

26%

#inKKAy

46%

#indb/db

BI38335

[105];41%

#non-fast

glucose

inKKAyat9-w

eek

tofogliflozin

[43]

HbA1c

NA

21--25%

#in

HFFFZDF[56];53%

#in

male

ZDF[106]

53%

#inmale

ZDF[104]

14%

#inGKrats

[46]

38%

#inSTZrats

35%

#after4-w

eek

tofogliflozinin

db/

dbmice[43];32%

#in

db/dbmicewith30d

EGT1442

[107]

FPI

42%

#indb/db

24%

#male

ZDFat

5weeks[41]

EGP

24%

#indb/db

76%

#EGPin

ZDFat

2weeks[106]

52%

#Ra4days

after

5weektreatm

ent[104]

Insulin

secretion

84%

"insulin

inhyperglycemic

clamp

93--83%

"disposition

index48hpost-33day

treatm

entin

HFFFZDF[56]

46%

"inGSIS

inislets

of

db/dbmicetreatedwith

BI38335

[105];160%

"free-fedIRIin

db/dbmice

after4-w

eek

tofogliflozin

[43]

Insulin

sensitivity

"insulin

sensitivity

(2-fold

"GIR

foreuglycemia)

150--300%

"insulin

sensitivity

inHFFZDFin

clamps48hpost-

dose;90%

#insulin

resistance

inDIO

S-D

rats

[108]

Reducedinsulin

regim

en

forglucose

controlin

STZrats

[109]

Thedata

were

selectedfrom

studiesthathave

evaluatedtheeffectsofdosinganSGLT2inhibitorforatleast

2weeksto

arodentmodelthatishyperglycemic.

AUC:Areaundertheplasm

aconcentration--tim

ecurve;EGP:Endogenousglucose

production;FPG:Fastingplasm

aglucose;FPI:Fastingplasm

ainsulin;GIR:Glucose

infusionrate;HFD

:Highfatdiet;HFFFZDF:

High

fat-fedfemale

ZDFrat;OGTT:Oralglucose

tolerance

test;STZ:Streptozotocin;ZDF:

Zuckerdiabeticfatty(rat).



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dapagliflozin in healthy volunteers was maintained throughouta 2-week study. For patients with T2DM (baseline HbA1cvalues of 8.0 -- 8.5%), the glucosuric response following oraladministration of these seven C-glucosides was immediatefrom day 1 resulting in 24-h UGE values of 70 -- 85 g andwas maintained throughout the study albeit with modestdiminution as the glycemic levels improved. Over the courseof the studies, FPG values progressively decreased by > 25%.Relative efficacies of these drugs cannot be inferred from thesedifferences in the UGE and FPG responses due to confoundinginfluences reflecting differences in glycemic levels (higherglucose AUC, more glucosuria) and study conditions (mealrestricted in clinic versus unrestricted).

8.2.2 Longer-term studiesResults have been reported for longer-term studies withT2DM patients for six compounds (Tables 10 and 11). Com-parison of the observed UGE responses after 4 weeks is diffi-cult because the baseline HbA1c levels ranged from ~ 7.2%for empagliflozin to ~ 8.2% for canagliflozin, ertugliflozinand LX4211 and were unspecified for ipragliflozin (Table 10).Ipragliflozin was associated with the greatest increase in UGEas well as decreases in FPG and body weight, raising thepossibility that inhibition of renal SGLT5 may be augmentingthe effect analogous to remogliflozin. However, the startingHbA1c uncertainty coupled with the patients being housedin a clinic for the duration renders assessment difficult.LX4211 produced the lowest UGE response, suggesting littlebenefit from SGLT1 inhibition in the kidney, although theimprovement in FPG was impressive. Confirmation of thistrend awaits longer studies with more patients, but it doespotentially support a beneficial incretin effect due to signifi-cant SGLT1 inhibition in the gastrointestinal tract.

The extensive multi-month studies conducted with dapagli-flozin and canagliflozin establish that each is associated withglycemic efficacy in patients with T2DM at any stage, eitheras monotherapy or in combination with other oral antidiabeticagents (OADs) or insulin. Long-term studies with dapagliflo-zin (up to 104 weeks of treatment) confirm the sustainedeffects on HbA1c and FPG levels. Results of metformin com-bination extended studies with either empagliflozin, luseogli-flozin or ertugliflozin suggest that the outcome for eachappears to be similar to that obtained with a dapagliflozin/metformin combination (Table 11).

Additionally, benefits beyond glycemic control have beendemonstrated. It is thought that reductions in glucotoxicityand weight lead to improvements in insulin sensitivity and secre-tion. In keeping with the observations in animal models, a12-week study in subjects with T2DM (with or without insulin)revealed that dapagliflozin improved insulin sensitivity as mea-sured by glucose disposal rate [65]. An additional study showedthat dapagliflozin as monotherapy or add-on to metforminimproved b-cell function and insulin sensitivity as measured bythe Homeostasis Model Assessment 2; however, this assessmentmodel is not specifically validated for SGLT2 inhibitors [66].T

able

6.Compariso

nofthelong-term

effectsofSGLT

2inhibitors

withtheSGLT

2KO

mouse

phenotypein

insu

lin-resistant/hyperglycemic

endpoints:

effectsongluco

suria,b-cellmass

andbodyfat.

SGLT

2KO

mouse

[51]

Dapagliflozin

Canagliflozin

[44]

Empagliflozin

Ipragliflozin

[103]

Others

Glucosuria

533%

"indb/db

>2,900%

"inZDF;

1,111%

"at5weeks[41]

1,500%

"inZDF(4

hr)

363%

"in

ZDF(acute)[104]

71%

"inKKAy;

63%

"inSTZrat

Urinevolume

59%

"indb/db

438%

"inZDF

after‡0.1

mg/kg

23--43%

"KKAy;

19%

"inSTZrat

12%

"indb/db4weeks

afterEGT1,442

[107]

b-cellmass

63%

"b-cell

volume

15%

"b-cellmass

(ns),

129%

"cellmorphology

index[56]

89%

"pancreatic

insulin

contentin

STZ

31%

"insulin

+ve

areaof

pancreasin

KKAymice

after9-w

eeksergliflozin

[110]

Body-fat

15%

#upto

8.8%

#bodyfatin

DIO

S-D

rats

[108]

12%

#epididym

al

fatpadin

ZDF

38%

#bodyfatat

8weekswhenfood

restrictedin

GK

rats

[111]

Thedata

were

selectedfrom

studiesthathave

evaluatedtheeffectsofdosinganSGLT2inhibitorforatleast

2weeksto

arodentmodelthatishyperglycemic.

EGP:Endogenousglucose

production;FPG:Fastingplasm

aglucose;STZ:Streptozotocin;ZDF:

Zuckerdiabeticfatty(rat).



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Although these SGLT2 inhibitors produced modest weightlosses, which were sustained throughout study duration, theweight changes were also dependent upon background therapy(Table 11). For example, dapagliflozin in combination withpioglitazone mitigated the weight gain generally associatedwith pioglitazone. A study of dapagliflozin or placebo asadd-on to metformin in patients with T2DM showed thatdapagliflozin was associated with mean total body weight lossof 2.08 kg after 24 weeks, predominantly due to the reductionof total body fat mass (-1.48 kg) and visceral and subcutaneousadipose tissue (-258.4 and -184.9 cm3, respectively) [67].

Modest reductions in BP have also been observed. Althoughan initial natriuresis has been observed with dapagliflozin, thisreturns to baseline within 2 weeks [68]. Therefore, it is antici-pated that osmotic diuresis and weight loss may both contributeto the reduction in BP. A small, exploratory study showed thatdapagliflozin was associated with a reduction in 24-h meansystolic BP that was less than that observed with hydrochlorothi-azide (daytime systolic BP reductions were similar, while dapa-gliflozin did not affect nighttime systolic BP) [69]. Assessmentin a subgroup of these patients showed that dapagliflozindecreased plasma volume, while placebo and hydrochloro-thiazide increased plasma volume [69]. A pooled analysis offive clinical trials with dapagliflozin showed that the greatestreductions in BP were observed in hypertensive patients.

8.3 Studies in patients with renal impairmentTo obtain the glycemic benefits of SGLT2 inhibition, glucosemust first be filtered from the blood in the renal glomeruliand its reabsorption must then be inhibited. Since progressiveloss of renal function diminishes the filtered glucose load, themaximum glucosuric response decreases with loss of renal func-tion. Studies with ipragliflozin and luseogliflozin have beenconducted to determine the stage of renal impairment at whichthe benefit derived from SGLT2 inhibitors would diminish.Administration of a single 100 mg dose of ipragliflozin tocohorts (n = 8) of healthy volunteers, to patients with T2DMhaving normal renal function (eGFR > 90 ml/min/1.73 m2)and to three cohorts of progressively renally impaired T2DMpatients -- mildly impaired (eGFR 60 -- 89), moderatelyimpaired (eGFR 30 -- 59) and severely impaired (eGFR< 29 ml/min/1.73 m2) -- produced respective amounts of24-h UGE of 45.6, 47.7, 61.5, 21.2 and 10.4 g of glucose [70].This decrease in UGE occurred despite the fact that relative tothe ipragliflozin area under the plasma concentration--timecurve (AUC) in healthy volunteers, the AUC of ipragliflozinwas 112, 143, 165 and 173%, respectively, for T2DM patientswith non-impaired, mildly impaired, moderately impaired andseverely impaired renal function. Similarly, a single 5 mg doseof luseogliflozin, administered to 57 T2DM patients subdi-vided into four cohorts based on renal function, resulted in

Table 7. Clinical studies with O-glucoside SGLT2 inhibitors (SADs and MADs).

SGLT2 inhibitor Study N Dose (mg) t1/2(hr)

Baseline

HbA1c

(%)

24 h UGE

(g)

D FPG vs

baseline

(mg/dl)

D Weight vs

baseline (kg)

Sergliflozin [62] 1 day, healthyvolunteers

158888

Placebo15 q.d.50 q.d.200 q.d.500 q.d.

1 -- 1.3 0.91.756.313.219.4

Sergliflozin [63] 14 days,obese healthyvolunteers

666

Placebo500 t.i.d.1,000 t.i.d.

0.15 ± 0.0120.7 ± 3.550.2 ± 8.3

--0.09 ± 0.47--1.55 ± 0.25--1.74 ± 0.71

Sergliflozin [62] 1 day, T2DM 8888

Placebo50 q.d.150 q.d.500 q.d.

1.3 -- 1.4 8.38.38.3~ 8.3

12.422.524.837.3

Remogliflozin [64] 1 day, healthyvolunteers

Placebo150 mg500 mg

2 ~ 034.940.5

Remogliflozin [90] 12 days, T2DM 8999

Placebo100 b.i.d.1,000 q.d.1,000 b.i.d.

1.4 -- 1.5 8.08.18.07.8

5.2 ± 5.691.6 ± 36165 ± 114103 ± 45

-23.4 ± 10-5.4 ± 10 0-41.4 ± 10

--1.6 ± 0.7--2.3 ± 0.63--4.5 ± 0.6--2.9 ± 0.64

Remogliflozin [112] 3 days, T2DMw/woutmetformin

131313

500 b.i.d.500 met b.i.d.500 b.i.d. w500 met

< 10< 10< 10

95 ± 24.3*4 ± 1.2*85 ± 16.7*

-9.9 ± 14.4*+1.1 ±13*--9.0 ± 10.8*

Table shows mean values, with ± SD, where available.

*Estimated from graph.

b.i.d.: Twice daily; FPG: Fasting plasma glucose; q.d.: Every day; t1/2: Half-life; t.i.d.: Three times daily; T2DM: Type 2 diabetes mellitus; UGE: Urinary

glucose excretion.



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24 h UGE values of 88.3, 69.7, 45.3 and 21.8 g of glucose [71].In a 26-week double-blind, placebo-controlled, Phase IIIstudy, 269 patients with T2DM and moderate renalimpairment (eGFR 30 -- 49 ml/min/1.73 m2) concurrentlyreceiving treatment with insulin or sulfonylureas were admini-stered canagliflozin at 100 mg q.d. or 300 mg b.i.d. [72]. After26 weeks, HbA1c reductions were 0.3 and 0.4% after placebocorrection rather than ~ 1% achieved by T2DM patients withnormal renal function. There were also modest changesin renal function compared to placebo [72]. Similarly,

dapagliflozin administered to patients with T2DM and mode-rate renal impairment resulted in a reduction of HbA1cof ~ 0.4 vs 0.3% for placebo, with no significant differencebetween treatment groups [73]. These studies suggest that, forpatients with T2DM and moderate renal impairment,SGLT2 inhibitors will confer less benefit than in patientswith T2DM and normal renal function, whereas patientswith T2DM and mild renal impairment should achieve bene-fits comparable to those achieved by patients with T2DM andnormal renal function.

Table 8. Clinical studies with C-glucoside SGLT2 inhibitors in healthy volunteers.

SGLT2 inhibitor Study N Dose (mg) t1/2(h)

Baseline

HbA1c

(%)

24 h UGE

(g)

D FPG vs

baseline

(mg/dl)

D Weight vs

baseline (kg)

Dapagliflozin [113] 14 days,healthyvolunteers

1066666

Placebo2.5102050100

17 ~ 020.433.649.253.355.4

Canagliflozin [114] 14 days, obesenon-T2DM

201212121212

Placebo30 q.d.100 q.d.300 q.d.600 q.d.300 b.i.d.

< 0.1 ± 0.049 ± 4.233 ± 9.747 ± 2350 ± 1361 ± 16

--1.4 ± 1.1*--2.9 ± 1.5*--2.7 ± 0.9*--2.1 ± 1.6*--3.4 ± 1.3*--3.5 ± 1.4*

Luseogliflozin [115] 1 day, healthyvolunteers

10388888

Placebo1 q.d.3 q.d.5 q.d.9 q.d.15 q.d.25 q.d.

9 -- 13 < 1*18 ± 1*36 ± 6*50 ± 3*54 ± 3*63 ± 4*72 ± 6*

Luseogliflozin [115] 7 days, healthyvolunteers

888

Placebo5 q.d.10 q.d.

< 1*~ 46*55 -- 60*

Ipragliflozin [95] 14 days, healthyvolunteers

1266666

Placebo5 q.d.30 q.d.100 q.d.300 q.d.600 q.d.

11 -- 15 0.11 ± 0.053.1 ± 0.72437.356.458.9 ± 14.6

Empagliflozin [116] 1 day, healthyvolunteers

18666666666

Placebo0.5 q.d.2.5 q.d.10 q.d.25 q.d.50 q.d.100 q.d.200 q.d.400 q.d.800 q.d.

8.6 -- 13 0.063.130.647.956.563.678.669.190.861.6

LX4211 [61] 1 day, healthyvolunteers

21010

Placebo400 q.d.400 b.i.d.

33*36*



b.i.d.: Twice daily; FPG: Fasting plasma glucose; q.d.: Every day; t1/2: Half-life; t.i.d.: Three times daily; T2DM: Type 2 diabetes mellitus; UGE: Urinary

glucose excretion.



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9. Safety

Very few serious adverse events (AEs) have been reported forthe SGLT2 inhibitors; moreover, the limited data suggest asimilar pattern of AEs across the class. The most extensiveanalysis of safety for an SGLT2 inhibitor is a retrospectivereview of 12 placebo-controlled studies with dapagliflozin,including > 4,500 patients who had received treatment forup to 12 weeks, and > 2,500 patients treated for up to104 week [74]. Extensive safety data are not available forother SGLT2 inhibitors; as such, the findings from thisanalysis will serve as being representative of the class untilmore data are available.

9.1 Renal safetyThe pooled analysis revealed that renal AEs were similar betweendapagliflozin and placebo [75]. During the first week of treatmentwith dapagliflozin, eGFR decreased by up to 4 ml/min/1.73 m2

in a dose-dependent fashion before slowly returning to baselineover the subsequent 24 weeks, whereupon no further changeswere noted. No AEs were associated with this change and thiseffect may be a result of the early hemodynamic change thatalso gives rise to small reductions in BP.

No change in electrolytes such as Na, K, Cl and HCO3 wereobserved during dapagliflozin treatment; initial increasesin serum phosphorous and magnesium were not maintained inlonger studies, suggesting that renal tubular function isunchanged [75]. Furthermore, no cases of tubular necrosis werereported nor did any dapagliflozin-treated patients require dialy-sis. Additionally, no adverse effect on albuminuria was noted [75].

9.2 HypoglycemiaThere appears to be a low risk of hypoglycemia associated withSGLT2 inhibitors, as a result of the insulin-independentmechanism of action. Dapagliflozin 10 mg as monotherapyor add-on to metformin was associated with a low incidenceof hypoglycemia (2.9 and 3.1% vs 2 and 3.1%, respectivelywith placebo). The risk of hypoglycemia was increased whendapagliflozin was used in combination with sulfonylureas(7.3 vs 4.8% with placebo) or insulin (42.3 vs 35% withplacebo) [74]. Initial results from other SGLT2 inhibitorsshow a similar low incidence of hypogylcemia [76,77].

9.3 Genital and urinary tract infectionsThere is a theoretical increased risk of urinary tract infections(UTIs) and genital infections due to the glucosuria associated

Table 9. Clinical studies with C-glucoside SGLT2 inhibitors in patients with T2DM (< 2 weeks’ duration).

SGLT2 inhibitor Study N Dose

(mg)

t1/2(h)

Baseline

HbA1c (%)

24-h UGE

(g)

D FPG vs

baseline

(mg/dl)

D Weight vs

baseline (kg)

Dapagliflozin [91] 14 days,naıve T2DM

8111216


16 0.7536.670.169.9

--5.2--18.8--28.8--38.7

Canagliflozin [117] 16 days,T2DM

191616161614

Placebo30 q.d.100 q.d.200 q.d.400 q.d.300 b.i.d.

8.37.97.78.08.38.2

--10 ± 1369 ± 3276 ± 2788 ± 35113 ± 2788 ± 38

--26--20--54--65--60--66

--1.25*--1*--2*--2.0*--1.9*--2.7*

Luseogliflozin [98] 7 days,T2DM

88888

Placebo0.5 q.d.1 q.d.2.5 q.d.5 q.d.

9 -- 10.5 8.58.68.08.78.0

0.2 ± 15*48.2 ± 15*68.3 ± 14*86.6 ± 15*103 ± 15*

Ipragliflozin [118] 14 days,T2DM

1099


8.48.48.1

5.3 ± 19.380.6 ± 22.289.7 ± 12.3

+0.3 ± 21--31.6 ± 24--35.8 ± 29

--0.2 ± 0.6--1.5 ± 0.5--1.2 ± 0.4

Empagliflozin [119] 8 days,T2DM

129999

Placebo2.5 q.d.10 q.d.25 q.d.100 q.d.

10 -- 19 7.16.97.07.06.5

-3.3 ± 8.334.6 ± 16.279 ± 53.574 ± 3588 ± 20.3

--21.7 ± 21--23.3 ± 11.1--40 ± 23.28--26.1 ± 28.4--38 ± 22.9

LX4211 [120] T2DMday 1

121212


13.5 -- 20.7 8.28.28.5

1*45*67*



b.i.d.: Twice daily; FPG: Fasting plasma glucose; q.d.: Every day; t1/2: Half-life; t.i.d.: Three times daily; T2DM: Type 2 diabetes mellitus; UGE: Urinary glucose excretion.



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with SGLT2 inhibitors. Furthermore, a higher incidence of UTIsand genital infections occurs in T2DM patients [78,79]. Activemonitoring of signs and symptoms of UTIs and genital infec-tions was, therefore, performed in the dapagliflozin trials. In thepooled analysis, UTIs with dapagliflozin 10 mg were slightly ele-vated versus placebo (4.3 vs 3.7%). Treatment with dapagliflozinincreased the incidence of vulvovaginitis, balanitis and relatedinfections over placebo from 0.9 to 4.8%. Most cases weremild to moderate and were treated with one course of standardtreatment, and there was a low rate of recurrence [74].Initial results with other SGLT2 inhibitors are broadly sim-

ilar, with an observed increase in genital infections. The inci-dence of UTIs with other SGLT2 inhibitors appears similarto comparator, although it is unclear how information onUTIs was collected, and several studies were of shortduration [76,77,80,81].

9.4 Volume depletionThe SGLT2 inhibitor diuretic effect was mild resulting inmodest BP reductions. Hypotension, dehydration or volumedepletion events were 0.8 and 0.4%, respectively, for dapagli-flozin 10 mg and placebo cohorts. Patients treated withdapagliflozin 10 mg experienced clinically significantdecreases in systolic and diastolic BP of -4.4 and -2.1 versus-0.9 and -0.5 mm Hg for placebo [74].

9.5 Other AEsThe potential risk for fractures was evaluated as gutSGLT1 inhibition can result in increased gut absorption of

calcium and an adaptive increase in urinary calcium excretion.Fracture risk was small and balanced between dapagliflozin10 mg (0.5%) and placebo (0.7%); there were no clinicallysignificant differences in hepatic function tests [74]. Therewere also no clear or consistent changes in lipids during dapa-gliflozin treatment, although changes in lipid profiles wereexploratory endpoints [82,83].

9.6 Rare eventsPooled analysis of 19 trials showed that the overall incidencerate (per 100 patient-years) of malignancies and unspecifiedtumors was similar between dapagliflozin and comparatorgroups (1.39 and 1.34, respectively) [74]. In the developmentprogram, nearly twice as many patients received dapagliflozincompared to comparator/placebo. In this experience, ninecases of bladder cancer were reported in the dapagliflozingroup as against one for placebo; additionally, breast cancerwas detected in 10 female patients in the dapagliflozin groupas against three in the placebo group. Due to the small num-ber of events, a cause and effect relationship cannot be deter-mined. The majority of events of bladder and breast cancerswere detected early in the study, suggesting that many werepreexistent [74]. Importantly, other SGLT2 inhibitors mayyet also reveal idiosyncratic safety issues with broaderpatient exposure.

Finally, pooled analysis of 19 trials suggest that dapagliflo-zin does not pose a cardiovascular risk, as the overall stratifiedanalysis for cardiovascular death, stroke, myocardial infarctionand unstable angina was 0.819 (95% CI: 0.583 -- 1.152).

Table 10. Clinical studies with C-glucoside SGLT2 inhibitors in patients with T2DM (4 weeks duration).

SGLT2 inhibitor Study N Dose

(mg)

t1/2(h)

Baseline

HbA1c (%)

24 h UGE

(g)

D FPG vs

baseline

(mg/dl)

D Weight vs

baseline (kg)

Canagliflozin [93] 28 days,T2DM withinsulin

91010

Placebo100 q.d.300 b.i.d.

8.278.368.42

--3.2 ± 15.671.9 ± 32.1129 ± 62.4

+8.7 ± 40.5--38 ± 21.5--42.4 ± 27.2

0.03 ± 0.6--0.7 ± 0.9--1.2 ± 1.4

Ipragliflozin [121] 28 days,T2DM

1312121212

Placebo50 q.d.100 q.d.200 q.d.300 q.d.

Notprovided

--9.4 ± 23.961.5 ± 3180.3 ± 35.282.7 ± 32.290.8 ± 16 4.4

--10.4--60.3 ± 12.6--49 ± 12.7--70.6 ± 13.3--65 ± 12.8

--1.8*--3.2*--3.9*--4.2*--4.0*

Empagliflozin [96] 28 days,T2DM

16161630


13 -- 16 6.97.27.57.1

--0.7 ± 4.764.4 ± 29.678.4 ± 6.972.6 ± 6.6

--4.1 ± 27.1--43.7 ± 81.8--34.2 ± 26.4--28.7 ± 18.3

02.611.561.49

Ertugliflozin [122,123] 28 days,T2DM

38343839


11 -- 17 8.218.388.058.31

4 ± 31*47 ± 31*64 ± 36*75 ± 36*

+4 ± 24*--14 ± 31 4*--30 ± 31*--31 ± 31*

LX4211 [120] 28 days,T2DM

121212


13.5 -- 20.7 8.28.28.5

--1*35*48*

--12*--52*--68*

-2-3-4



b.i.d.: Twice daily; FPG: Fasting plasma glucose; q.d.: Every day; t.i.d: Three times daily; t1/2: Half-life; T2DM: Type 2 diabetes mellitus; UGE: Urinary glucose excretion.



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Table

11.ClinicalstudiesforC-gluco

sideSGLT

2inhibitors

(>1month

induration).

SGLT

2

inhibitor

Duration;

background

therapy

NDose

(mg)

HbA1cat

baseline

(%)

DHbA1c

from

baseline(%

)

DFP

G(SE)

(mg/dl)

DW

eight

(kg)

DSBP

(mmHg)

AEs(n)

SAE;UTI;

GenI;Hypo

Dapagliflozin

[82]

12weeks;

Drugnaive

54

59

58

47

59

56

56

Placebo

2.5

5 10

20

50

Metform

in

7.9

7.6

8.0

8.0

7.7

7.8

7.6

--0.18±0.015

--0.71±0.01

--0.72±0.01

--0.85±0.016

--0.55±0.01

--0.9

±0.014

--0.73±0.014

--6±0.4

--16±0.4

--19±0.4

--21±0.6

--24±0.4

--31±0.4

--18±0.4

--1.1

--2.4

--2.2

--2.3

--3.0

--3.1

--1.5

0;3;0;2

1;3;2;4

0;5;1;6

1;5;1;3

1;7;4;4

1;5;4;4

1;5;1;5

Dapagliflozin

[124]

12weeks;

OADandinsulin

23

24

24

Placebo

10

20

8.4

8.4

8.5

+0.09(--0.2,0.4)

--0.61(--0.9,-0.4)

--0.69(-0.9,-0.4)

+17.8

(1.4,34.2)

+2.4

(--13.6,18.3)

--9.6

(--25.6,6.3)

--1.9

(--2.9,-0.9)

--4.5

(--5.5,-3.5)

--4.3

(--5.3,--3

.3)

1;0;1;3

0;0;0;7

1;1;5;6

Dapagliflozin

[83]

24weeks;

Drugnaive

75

65

64

70

39

Placebo

2.5

5 10

10

7.84

7.92

7.86

8.01

10.73

--0.23±0.1

--0.58±0.11

--0.77±0.11

--0.89±0.11

--2.66±1.26

--4.1

±3.9

--15.2

±4.2

--24.1

±4.3

--28.8

±4.0

--84.3

±61

--2.2

±0.4

--3.3

±0.5

--2.8

±0.5

--3.2

±0.5

--1.9

±3.5

--0.9

±1.8

--4.6

±1.8

--2.3

±1.9

--3.6

±1.9

--2.5

±2.1

6;7;1;2

6;3;5;1

1;8;5;0

0;4;9;2

0;6;7;0

Dapagliflozin

[125]

24weeks;

Metform

in137

137

137

135

Placebo

2.5

5 10

8.11

7.99

8.17

7.92

--0.30(--0.44,--0

.16)

--0.67(--0.81,--0

.53)

--0.70(--0.85,--0

.56)

--0.84(--0.98,--0

.70)

--6(--11.2,--0

.7)

--17.8

(--23.0,--1

2.6)

--21.4

(--26.8,--1

6.2)

--23.4

(--28.8,--1

8.0)

--0.9

(--1.4,--0

.4)

--2.2

(--2.7,--1

.8)

--3.0

(--3.5,--2

.6)

--2.9

(--3.3,--2

.4)

5;11;7;4

4;6;11;3

4;10;18;5

4;11;12;5

Dapagliflozin

[126,127]

24weeks;

Insulin

193

202

211

194

Placebo

2.5

5 10

8.47

8.46

8.62

8.57

--0.39

--0.79(--0.54,--0

.25)z

--0.89(--0.65,--0

.34)z

--0.96(--0.72,--0

.42)z

+0.43

--0.92(--1.9,--0

.8)z

--1.0

(--1.97,--0

.88)z

--1.61(--2.59,--1

.48)z

NR;8;4;NR

NR;15;10;NR

NR;19;16;NR

NR;17;18;NR

48weeks

193

202

211

194

Placebo

2.5

5 10

8.47

8.46

8.62

8.57

--0.47

--0.79(--0.48,--0

.16)z

--0.96(--0.65,--0

.33)z

--1.01(--0.70,--0

.38)z

+0.82

--0.96(--2.53,--1

.03)z

--1.0

(--2.56,--1

.07)z

--1.61(--3.18,--1

.68)z

26;10;5;102

27;16;13;122

19;23;21;118

23;20;21;105

104weeks

193

202

211

194

Placebo

2.5

5 10

8.47

8.46

8.62

8.57

--0.43

--0.64(--0.41,--0

.01)z

--0.82(--0.59,--0

.18)z

--0.8

(--0.56,--0

.15)z

+1.8*

--0.9*(--3.78,--1

.65)z

--0.9*(--3.80,--1

.69)z

--1.35*(--4.24,--2

.14)z

39;11;6;122

39;17;15;140

32;28;27;130

36;27;28;119

Table

showsmean±SEormean(95%

CI).

*Estim

atedfrom

graph.

z 95%

CIversusplacebo.

AE:Adverseevent;FPG:Fastingplasm

aglucose;GenI:Genitalinfections;

Hypo:Hypoglycemia;NR:Notreported;SAE:SeriousAE;SBP:Systolic

bloodpressure;UTI:Urinary

tract

infection.



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Table


sideSGLT

2inhibitors

(>1month

induration)(continued).

SGLT

2

inhibitor

Duration;

background

therapy

NDose

(mg)

HbA1cat

baseline

(%)

DHbA1c

from

baseline(%

)

DFP

G(SE)

(mg/dl)

DW

eight

(kg)

DSBP

(mmHg)

AEs(n)

SAE;UTI;

GenI;Hypo

Dapagliflozin

[128]

48weeks;

Sitagliptin

100mgstratum

111

110

Placebo

10

8.07

7.99

+0.85(0.45,1.25)*

0.0

(--0.22,+0.61)*

+0.8

(0.0,1.6)*

--1.3

(--1.19,--0

.7)*

Sitagliptin

100mg+

metform

instratum

113

113

Placebo

10

7.87

7.80

+0.13(--0.03,0.29)*

--0.43(--0.55,-0.31)*

--0.4

(--1.3,+1.2)*

--2.6

(--3.3,-2.0)*

18;8;1;14

15;13;21;12

Dapagliflozin

[129]

52weeks;

Metform

in400

401

2--10

5--20Glip

7.69

7.74

--0.52(--0.60,--0

.44)

--0.52(--0.6,--0

.44)

--3.22(--3.56,--2

.87)

+1.44(1.09,1.78)

35;30;50;14

46;17;11;162

Dapagliflozin

[130]

24weeks;

Glim

epiride

145

154

142

151

Placebo

2.5

5 10

8.15

8.11

8.12

8.07

--0.13

--0.58(--0.61,--0

.27)z

--0.63(--0.67,--0

.30)z

--0.82(--0.86,--0

.31)z

--2.0

--16.76

--21.3

--28.5

--0.72

--1.18(--1.08,+0.15)z

--1.56(--1.47,--0

.21)z

--2.26(--2.17,--0

.92)z

--1.2

--4.7

--4.0

--5.0

7;5;1;7

11;4;6;11

10;4;9;10

9;4;10;12

Dapagliflozin

[131]

48weeks;

Pioglitazone

139

141

140

Placebo

5 10

8.34

8.40

8.37

--0.54(--0.70,--0

.38)

--0.95(--1.10,--0

.80)

--1.21(--1.36,--1

.06)

--13.1

(--20.0,--6

.0)

--22.8

(--29.1,--1

6.4)

--33.1

(--39.0,--2

7.2)

+2.99(2.99,3.79)

+1.35(--0.61,2.09)

+0.69(--0.03,1.41)

+2.0

±1.2

--1.0

±1.1

--2.2

±1.2

4;11;4;1

6;12;13;3

2;7;12;0

Dapagliflozin

[132]

24weeks;

Drugnaive

194

203

201

211

219

208

5+Met

5+PBO

Met+PBO

10+Met

10+PBO

Met+PBO

9.2

9.1

9.2

9.1

9.1

9.1

--2.05(--2.23,--1

.88)

--1.19(--1.36,--1

.02)

--1.35(--1.53,--1

.18)

--1.98(--2.13,--1

.83)

--1.45(--1.59,--1

.31)

--1.44(--1.59,--1

.29)

--3.39(--3.69,--3

.09)

--2.33(--2.63,--2

.04)

--1.86(--2.16,--1

.57)

--3.35(--3.62,--3

.07)

--2.58(--2.85,--2

.30)

--1.93(--2.21,--1

.65)

--2.66(--3.14,--2

.19)

--2.61(--3.07,--2

.15)

--1.29(--1.76,--0

.82)

--3.33(--3.80,--2

.86)

--2.73(--3.19,--2

.27)

--1.36(--1.83,--0

.89)

--2.9

(0.9)

--4.2

(0.9)

--1.8

(0.9)

--3.3

(0.9)

--4.0

(0.9)

--1.2

(1.0)

6;10;2;5

9;9;3;0

7;10;0;0

3;6;7;7

5;17;11;2

4;4;1;6

Canagliflozin

[133]

12weeks;

Metform

in65

64

64

65

64

64

65

Placebo

50

100

200

300

300b.i.d.

100Sita

7.7

8.0

7.8

7.6

7.7

7.7

7.6

--0.22±0.08

--0.79±0.08

--0.76±0.15

--0.7

±0.07

--0.92±0.07

--0.95±0.08

--0.74±0.07

+3.6

±2.5*

--16.2

±3.6*

--25.2

±2.5*

--27±3.6*

--25.2

±2.5*

--23.4

±2.5*

--12.6

±2.5*

--1.1

±0.26

--2.3

±0.3

--2.6

±0.26

--2.7

±0.3

--3.4

±0.3

--3.4

±0.26

--0.8*±0.3

1;4;1;NR

1;3;5;NR

1;2;4;NR

1;6;2;NR

1;2;2;NR

1;3;4;NR

0;1;1;NR

Canagliflozin

[72]

26weeks;

moderate

renal

impairment;

Insulin

orSU

90

90

89

Placebo

100q.d.

300q.d.

8.0

7.9

8.0

--0.03±0.09

--0.33±0.09

--0.44±0.09

+0.5

±5.1

--14.9

±5.4

--11.7

±5.4

+0.2

±0.26

--1.2

±0.3

--1.4

±0.28

--0.3

±1.5

--6.1

±1.5

--6.4

±1.5

16;5;0

10;5;2;yes

10;7;2;yes

Canagliflozin

[134]

26weeks;

Metform

in&

sulfonyurea

156

157

156

Placebo

100q.d.

300q.d.

8.1

8.1

8.1

--0.13±0.08

--0.85±0.08

--1.06±0.08

+4.13±3.6

--18.2

±3.6

--30.5

±3.7

--0.8

±0.3

--1.9

±0.27

--2.5

±0.3

--2.7

±1

--4.9

±1

--4.3

±1

9;8;5

5;10;17;yes

6;9;15;yes

Table


CI).

*Estim

atedfrom

graph.

z 95%

CIversusplacebo.





tract

infection.



Exp

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lthca

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03/2

0/13

For

pers

onal

use

onl

y.

Table


sideSGLT

2inhibitors

(>1month

induration)(continued).

SGLT

2

inhibitor

Duration;

background

therapy

NDose

(mg)

HbA1cat

baseline

(%)

DHbA1c

from

baseline(%

)

DFP

G(SE)

(mg/dl)

DW

eight

(kg)

DSBP

(mmHg)

AEs(n)

SAE;UTI;

GenI;Hypo

Canagliflozin

[135]

52weeks;

Metform

in483

485

482

100q.d.

300q.d.

glim

epiride

7.8

7.8

7.8

--0.82±0.04

--0.93±0.04

--0.81±0.04

--24.3

±1.6

--27.5

±1.6

--18.3

±1.6

--3.7

±0.17*

--4.0

±0.17*

+0.7

±0.14

--3.3

±0.6

--4.6

±0.6

+0.2

±0.6

24;31;43;NR

26;31;54;NR

39;22;8;NR

Canagliflozin

[136]

52weeks;

Metform

in+

sulfonylurea

377

378

300q.d.

100Sita

(sitagliptin)

8.1

8.1

--1.03±0.05

--0.66±0.05

--29.9

±2.2

--5.9

±2.2

--2.3

±0.2

+0.1

±0.2

--5.1

±0.7

+0.9

±0.7

24;15;45;yes

21;21;8;yes

Luseogliflozin

[137]

12weeks;

Metform

in56

55

55

54

58

Placebo

1q.d.

2.5

q.d.

5q.d.

10q.d.

7.9

7.8

8.1

7.9

8.0

+0.23±0.07*

--0.29±0.05*

--0.42±0.11*

--0.46±0.07*

--0.43±0.07*

--19.6

(--27.0,--1

2.1)z

--27.6

(--35.0,--2

0.1)z

--30.1

(--37.6,--2

2.5)z

--30.1

(--37.4,--2

2.7)z

--0.96(--1.48,--0

.44)z

--1.54(--2.06,--1

.02)z

--2.12(--2.65,--1

.6)z

--2.05(--2.57,--1

.54)z

--4.9

z

--5.2

z

--4.8

z

--6.8

z

1;NR;NR;0

0;NR;NR;0

1;NR;NR;0

1;NR;NR;0

0;NR;NR;0

Empagliflozin

[76]

78weeks

106

109

56

10q.d.

25q.d.

Metform

in

7.89

8.00

8.15

--0.34(--0.54,--0

.14)

--0.47(--0.66,--0

.27)

--0.56(--0.79,--0

.33)

--30.4

(--37.1,--2

3.7)

--27.8

(--34.3,--2

1.3)

--26.0

(--33.5,--1

8.4)

--2.24(--3.12,--1

.31)

--2.61(--3.41,--1

.77)

--1.28(--2.30,--0

.26)

0.12

--1.66

+1.96

10;4;5;1

7;7;6;2

3;2;1;4

Empagliflozin

[76]

78weeks;

Metform

in166

166

56

10q.d.

25q.d.

Sita

7.88

7.91

8.03

--0.34(--0.47,--0

.21)

--0.63(--0.76,--0

.50)

--0.4

(--0.60,--0

.20)

--21.3

(--26.4,--1

6.2)

--31.8

(--36.8,--2

6.7)

--15.6

(--23.6,--7

.62)

--3.14(--3.89,--2

.38)

--4.03(--4.77,--3

.29)

--0.41(--1.49,+0.67)

--3.28

--2.97

+1.83

10;15;5;4

13;21;6;6

9;7;0;3

Ertugliflozin

[100]

12weeks;

Metform

in54

54

55

55

55

55

Placebo

1 5 10

25

Sita

100mg

8.08

8.0

7.88

8.13

8.3

8.24

--0.11±0.11

--0.56±0.11

--0.8

±0.11

--0.73±0.11

--0.83±0.11

--0.87±0.11

+2.8

±4.1

--18.2

±4.0

--23.1

±4.0

--31.5

±4.1

--29.3

±4.1

--17.3

±4.0

--0.75±0.34

--1.9

±0.33

--2.5

±0.33

--2.9

±0.34

--2.7

±0.34

--0.3

±0.33

--0.53±1.6

--2.69±1.5

--4.0

±1.5

--3.43±1.6

--3.93±1.6

--1.09±1.5

NR;4;1;0

NR;2;0;1

NR;0;1;1

NR;5;3;1

NR;0;4;1

NR;1;0;1

Table


CI).

*Estim

atedfrom

graph.

z 95%

CIversusplacebo.





tract

infection.



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10. Conclusions

Studies to date reveal that SGLT2 inhibitors provide an effica-cious means for the treatment of T2DM, resulting in HbA1creductions. Evidence also suggests that by inducing glucosuria,glucotoxicity is sufficiently diminished so that the liver becomesinsulin responsive and, as a consequence, hepatic glucose out-put decreases, thereby promoting b-cell preservation. SGLT2inhibitors can be employed throughout the continuum of dis-ease as monotherapy, or in combination with other OADsand with insulin, consistent with their insulin-independentmechanism of action. Additionally, long-term maintenanceof efficacy has been observed. However, only the GFR ofT2DM patients having normal or mildly impaired renal func-tion generates sufficient glucose load in the glomerular filtrateto fully benefit from this class of antidiabetics.Clinical trials with eight SGLT2 inhibitors are being pur-

sued. Development of ipragliflozin was recently discontinued,due to commercial reasons. The HbA1c and FPG reductionsachieved in short-term trials, reported for seven SGLT2inhibitors, appear similar, despite differences in selectivityand potency. Due to a transient high gastrointestinal concen-tration, each compound should, to varying degrees, tran-siently inhibit SGLT1 in the gastrointestinal tract to inducea beneficial incretin effect in addition to inhibition of renalSGLT2 and, depending on the inherent selectivity, potentiallySGLT1 and SGLT5 in the kidney. Insufficient safety datahave yet been disclosed to distinguish among these agents.The demonstrated low risk of this class inducing hypogly-cemia is attributed to its insulin-independent mechanism thatdoes not compromise the hepatic counter-regulatory pathways.The most advanced members are dapagliflozin, approved in theEuropean Union and Australia, and canagliflozin, awaitingreview of a New Drug Application package. Canagliflozinwas recently evaluated by an FDA Advisory Committee. TheAdvisory Committee generated a positive 10 for and 5 againstvote to recommend the approval of canagliflozin for the treat-ment of T2DM patients. However, the Committee noted thenumeric imbalance in early (< 30 day) major cardiovascularevents reported from CANVAS, a cardiovascular outcomestrial, and the imbalance of fracture incidence, noting a possiblerelationship to the proposed mechanism of action [84,85]. TheAdvisory Committee, with their positive vote, noted the needfor long-term cardiovascular safety information [84,85].

11. Expert opinion

SGLT2 inhibitors offer a new approach for the treatment ofT2DM that is independent from the secretion and actionsof insulin for their efficacy. They are, therefore, a class ofcompounds that could be used in combination with otheragents. SGLT2 inhibitors also provide benefits beyond acuteglucose-lowering, including preservation of islet functionand mass, improved insulin action due to the reduction ofglucose toxicity and reductions in weight and BP.

Of the different agents, luseogliflozin is the most selectiveover SGLT1. The majority are at least 260-fold selective,with the exception of LX4211, which has only 20-fold selec-tivity. The increased incretin responses observed during oralglucose challenge with LX4211 might provide an advantagein the long-term over the other agents. In addition, inhibi-tion of the more broadly distributed SGLT1 transporters incardiac and skeletal muscle could lead to longer-term safetyissues. It has already been shown, at least preclinically, thata less selective agent has a greater risk for hypoglycemia asthere is a blunting of the compensatory responses to counter-act this risk versus that seen with selective agents, such astofogliflozin [86,87].

Although the potency as SGLT2 inhibitors for all agents isin the nanomolar range, the doses utilized during Phase IIItrials spanning 2.5 -- 300 mg differ substantially. While thesedifferent doses have delivered similar efficacy in terms of gly-cemic control and reduction of body weight, there will clearlybe a greater exposure for the agents given in larger doses. Thisincreases the risk of off-target AEs, particularly those that arerare and only detected from long-term experience.

One of the key debates at present is, if SGLT2 transportersare responsible for most of the filtered glucose recovery,why do the small-molecule inhibitors of SGLT2 onlyinhibit ~ 30 -- 50% of the renal tubular reabsorption of filteredglucose? For example, for healthy volunteers, the maximumdaily UGE that can be induced by dapagliflozin was ~ 60 gor 33% of total filtered glucose. Many explanations havebeen proposed to account for this finding [88]; alternatively,this apparent conundrum may be resolved if the total renalrecovery capacity is employed as the reference rather than thefiltered load. For a healthy individual with an average bloodglucose level of 100 mg/dl and a Tm of 200 mg/dl, the dailyfiltered load is 180 g, but the total recovery capacity is double(360 g). For UGE to be 60 g, the excess recovery capability(180 g) must be inhibited along with one-third of the normallyutilized capacity (180 g; i.e., 240 g in total). By this analysis,two-third of the total renal capacity is mediated bySGLT2 and is subject to inhibition by SGLT2 inhibitors. Pre-sumably the remaining one-third of renal recovery capacityreflects the action of SGLT1 present in the S2/S3 segmentsof the proximal tubule, as well as possible transport by SGLT5.

Experience with dapagliflozin showed no overall imbalancein malignant and unspecified tumors across the developmentprogram as anticipated from the preclinical animal genotoxicand carcinogenicity studies, which showed no increased tumorrisk with dapagliflozin at exposures up to 100 times the humanclinical exposure at 10 mg. However, there was a numericalimbalance in the small number of breast and bladder cancersreported, with more cases in dapagliflozin groups. Due to thesmall number of events, a cause and effect relationship cannotbe determined, but overall, the weight of evidence does notfavor a causal link between dapagliflozin and cancer. Post-marketing studies are planned to further evaluate these find-ings. Dapagliflozin has now been approved by the European



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Authorities, illustrating that some important questions canonly truly be answered post-approval and that robustpost-marketing trials are needed for evaluation of rare events.

Acknowledgments

The authors would like to thank Jean Whaley for helpfulcomments on the early stages of the manuscript.

Declaration of interest

W Washburn is an employee and shareholder of Bristol-Myers Squibb and S Poucher was an employee of AstraZenecaduring the development of this article and is a shareholder ofAstraZeneca. Medical writing support was provided byCaroline Allinson of PPSI (a PAREXEL Co.) and was fundedby AstraZeneca and Bristol-Myers Squibb.

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AffiliationWilliam N Washburn†1 &

Simon M Poucher2 BSc (Hons) PhD

FBPharmacolS†Author for correspondence1Metabolic Diseases Chemistry,

Research and Development,

Bristol-Myers-Squibb Co.,

Princeton, NJ, USA

Tel: + 609 818 4971;

E-mail: [email protected] Scientist,

Cardiovascular and Gastro-Intestinal Disorders

Innovative Medicines, AstraZeneca

Pharmaceuticals, Macclesfield,

Cheshire, UK



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