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Sodium-glucose cotransporters 1 (SGLT1) and 2 (SGLT2) are the major cellular transporters responsible for gastrointestinal (GI) glucose absorption and renal glucose reabsorption, respectively. LX4211, a dual inhibitor of SGLT1 and SGLT2, reduces glucose absorption from the GI tract and enhances urinary glucose excretion. Although several SGLT2-selective inhibitors have been tested in large phase 2 studies, dual inhibition of SGLT1 and SGLT2 is novel at this stage of drug development, and it has implications for clinical-trial design. In this article, we describe the design and rationale of a phase 2, multicenter, randomized, double-blind, placebo-controlled, parallel group study to evaluate the safety and efficacy of LX4211 in subjects with type 2 diabetes mellitus who have inadequate glycemic control on metformin monotherapy. The primary endpoint is the change in glycated hemoglobin A1c from baseline to week 12. Secondary endpoints include the proportion of subjects achieving a glycated hemoglobin A1c value of

Thirty-six patients with type 2 diabetes mellitus (T2DM) were randomized 1:1:1 to receive a once-daily oral dose of placebo or 150 or 300 mg of the dual SGLT1/SGLT2 inhibitor LX4211 for 28 days. Relative to placebo, LX4211 enhanced urinary glucose excretion by inhibiting SGLT2-mediated renal glucose reabsorption; markedly and significantly improved multiple measures of glycemic control, including fasting plasma glucose, oral glucose tolerance, and HbA(1c); and significantly lowered serum triglycerides. LX4211 also mediated trends for lower weight, lower blood pressure, and higher glucagon-like peptide-1 levels. In a follow-up single-dose study in 12 patients with T2DM, LX4211 (300 mg) significantly increased glucagon-like peptide-1 and peptide YY levels relative to pretreatment values, probably by delaying SGLT1-mediated intestinal glucose absorption. In both studies, LX4211 was well tolerated without evidence of increased gastrointestinal side effects. These data support further study of LX4211-mediated dual SGLT1/SGLT2 inhibition as a novel mechanism of action in the treatment of T2DM.

Serotonin produced by neuroendocrine tumors is believed to be a principal cause of the diarrhea in carcinoid syndrome. We assessed the safety and efficacy of telotristat etiprate, an oral serotonin synthesis inhibitor, in patients with diarrhea associated with carcinoid syndrome. In this prospective, randomized study, patients with evidence of carcinoid tumor and ≥4 bowel movements (BMs)/day despite stable-dose octreotide LAR depot therapy were enrolled in sequential, escalating, cohorts of four patients per cohort. In each cohort, one patient was randomly assigned to placebo and three patients to telotristat etiprate, at 150, 250, 350, or 500 mg three times a day (tid). In a subsequent cohort, one patient was assigned to placebo and six patients to telotristat etiprate 500 mg tid. Patients were assessed for safety, BM frequency (daily diary), 24 h urinary 5-hydroxyindoleacetic acid (u5-HIAA), and adequate relief of carcinoid gastrointestinal symptoms (using a weekly questionnaire). Twenty-three patients were treated: 18 received telotristat etiprate and five received placebo. Adverse events were generally mild. Among evaluable telotristat etiprate-treated patients, 5/18 (28%) experienced a ≥30% reduction in BM frequency for ≥2 weeks, 9/16 (56%) experienced biochemical response (≥50% reduction or normalization in 24-h u5-HIAA) at week 2 or 4, and 10/18 (56%) reported adequate relief during at least 1 of the first 4 weeks of treatment. Similar activity was not observed in placebo-treated patients. Telotristat etiprate was well tolerated. Our observations suggest that telotristat etiprate has activity in controlling diarrhea associated with carcinoid syndrome. Further studies confirming these findings are warranted.

Background LX4211 is a first-in-class dual inhibitor of sodium-dependent glucose cotransporters 1 and 2 (SGLT1 and SGLT2). SGLT1 is the primary transporter for glucose absorption from the gastrointestinal tract, and SGLT2 is the primary transporter for glucose reabsorption in the kidney. SGLT1 inhibition reduces postprandial glucose (PPG) levels and increases the release of gastrointestinal peptides such as glucagon-like peptide 1 (GLP-1) and peptide tyrosine tyrosine (PYY), whereas SGLT2 inhibition results in increased urinary glucose excretion (UGE). Objectives This study evaluated how timing of dose relative to meals changes the pharmacodynamic (PD) effects of LX4211 treatment, including effects on UGE, fasting plasma glucose, PPG, insulin, total and active GLP-1, and PYY. The safety and tolerability of LX4211 in healthy subjects were also assessed. Methods This was a randomized, double-blind, placebo-controlled, multiple-dose study to determine the PD effects of LX4211 dose timing relative to meals in 12 healthy subjects. Blood and urine were collected for the analysis of PD variables. Results Twelve healthy subjects 30 to 51 years of age were enrolled and treated. Treatment with LX4211 resulted in significant elevation of total and active GLP-1, and PYY while significantly decreasing PPG levels relative to placebo, likely by reducing SGLT1-mediated intestinal glucose absorption. Comparisons performed among the dosing schedules indicated that dosing immediately before breakfast maximized the PD effects of LX4211 on both SGLT1 and SGLT2 inhibition. The comparative results suggested distinct SGLT1 effects on GLP-1, PYY, glucose, and insulin, which were separate from SGLT2-mediated effects, indicating that SGLT1 inhibition with LX4211 may be clinically meaningful. All treatments were well tolerated with no evidence of diarrhea with LX4211 treatment. Conclusions This clinical study indicates that dosing of LX4211 immediately before breakfast maximized the PD effects of both SGLT1 and SGLT 2 inhibition and provided a convenient dosing schedule for future trials. LX4211 was safe and well tolerated and, due to its SGLT1 inhibition, produced strong PPG reductions and low UGE relative to selective SGLT2 inhibitors. LX4211 may provide a promising new therapy for patients with type 2 diabetes mellitus. The potential long-term clinical benefits and safety of LX4211 treatment will need to be confirmed in large clinical trials. ClinicalTrials.gov identifier: NCT01334242.

Background & Aims Serotonin (5-hydroxytryptamine [5-HT]) has an important role in gastrointestinal function. LX1031 is an oral, locally acting, small molecule inhibitor of tryptophan hydroxylase (TPH). Local inhibition of TPH in the gastrointestinal tract might reduce mucosal production of serotonin (5-HT) and be used to treat patients with nonconstipating irritable bowel syndrome (IBS). Methods We evaluated 2 dose levels of LX1031 (250 mg or 1000 mg, given 4 times/day) in a 28-day, multicenter, randomized, double-blind, placebo-controlled study of 155 patients with nonconstipating IBS. 5-hydroxyindoleacetic acid (5-HIAA), a biomarker of pharmacodynamic activity, was measured in urine samples at baseline (24 hours after LX1031 administration), and at weeks 4 and 6 (n = 76). Results Each dose of LX1031 was safe and well-tolerated. The primary efficacy end point, relief of IBS pain and discomfort, improved significantly in patients given 1000 mg LX1031 (25.5%), compared with those given placebo, at week 1 ( P = .018); with nonsignificant improvements at weeks 2, 3, and 4 (17.9%, 16.3%, and 11.6%, respectively). Symptom improvement correlated with a dose-dependent reduction in 5-HIAA, a marker for TPH inhibition, from baseline until week 4. This suggests the efficacy of LX1031 is related to the extent of inhibition of 5-HT biosynthesis. Stool consistency significantly improved, compared with the group given placebo, at weeks 1 and 4 ( P P Conclusions In a phase 2 study, LX1031 was well tolerated, relieving symptoms and increasing stool consistency in patients with nonconstipating IBS. Symptom relief was associated with reduced levels of 5-HIAA in urine samples. This marker might be used to identify patients with nonconstipating IBS who respond to inhibitors of 5-HT synthesis.

Background Combination therapy is required to provide adequate glycemic control in many patients with type 2 diabetes mellitus (T2DM). Because sodium-dependent glucose transporter (SGLT)-1 inhibition results in an increased release of glucagon-like peptide (GLP)-1, and because dipeptidyl peptidase (DPP)-4 inhibitors prevent its inactivation, the 2 mechanisms together provide an intriguing potential combination therapy. Objectives This combination was explored in preclinical models and then tested in patients with T2DM to compare the effects of single-dose LX4211 400 mg and sitagliptin 100 mg, administered as monotherapy or in combination, on GLP-1, peptide tyrosine tyrosine (PYY), gastric inhibitory peptide (GIP), glucose, and insulin. Methods Preclinical: Obese male C57BL6J mice were assigned to 1 of 4 treatment groups: LX4211 60 mg/kg, sitagliptin 30 mg/kg, LX4211 + sitagliptin, or inactive vehicle. Clinical: This 3-treatment, 3-crossover, randomized, open-label study was conducted at a single center. Patients on metformin monotherapy were washed out from metformin and were randomly assigned to receive sequences of single-dose LX4211, sitagliptin, or the combination. In both studies, blood was collected for the analysis of pharmacodynamic variables (GLP-1, PYY, GIP, glucose, and insulin). In the clinical study, urine was collected to assess urinary glucose excretion. Results Preclinical: 120 mice were treated and assessed (5/time point/treatment group). With repeat daily dosing, the combination was associated with apparently synergistic increases in active GLP-1 relative to monotherapy with either agent; this finding was supported by findings from an additional 14-day repeated-dose experiment. Clinical: 18 patients were enrolled and treated (mean age, 49 years; 56% male; 89% white). The LX4211 + sitagliptin combination was associated with significantly increased active GLP-1, total GLP-1, and total PYY; with a significant reduction in total GIP; and with a significantly improved blood glucose level, with less insulin, compared with sitagliptin monotherapy. LX4211 was associated with a significant increase in total GLP-1 and PYY and a reduced total GIP, likely due to a reduction in SGLT1-mediated intestinal glucose absorption, whereas sitagliptin was associated with suppression of all 3 peptides relative to baseline. All treatments were well tolerated, with no evidence of diarrhea with LX4211 treatment. Conclusions The findings from the preclinical studies suggest that the LX4211 + sitagliptin combination produced synergistic increases in active GLP-1 after a meal challenge containing glucose. These initial clinical results also suggest that a LX4211 + DPP-4 inhibitor combination may provide an option in patients with T2DM. The potential long-term clinical benefits of such combination treatment need to be confirmed in large clinical trials. ClinicalTrials.gov identifier: NCT01441232 .

4085 Background: Diarrhea associated with carcinoid syndrome has been attributed to tumor production of serotonin. Telotristat etiprate, (LX1032, LX1606), is an oral inhibitor of peripheral serotonin synthesis. This study explored the safety, tolerability, and efficacy of telotristat etiprate in carcinoid patients with octreotide-refractory diarrhea. Methods: Carcinoid patients with ≥4 bowel movements (BMs)/day on octreotide were randomized 3:1 to receive telotristat etiprate or placebo as double-blind treatment. Patients enrolled in sequential, escalating dose cohorts of 150, 250, 350, or 500 mg tid, followed by a 500 mg tid expansion cohort. Patients were followed for toxicity, 24-hr urinary 5-HIAA (u5-HIAA), BM frequency, and self-reported bowel-related symptoms. Subjects were asked “In the past 7 days, have you had adequate relief of your carcinoid syndrome bowel complaints such as diarrhea, urgent need to have a bowel movement, abdominal pain or discomfort?” Responses (yes or no) were analyzed as categorical variables. Results: 16 patients enrolled in the 4 escalating dose cohorts and 7 in the expansion cohort; 18 on telotristat etiprate and 5 on placebo. Median age: 62 yrs; mean 6.3 BMs/day (range, 4-10). AEs included primarily mild-moderate diarrhea, nausea, and abdominal discomfort. In treated subjects, adequate relief was reported as: Week 1 - 6/18 (33.3%), Week 2 - 5/16 (31.3%), Week 3 - 5/15 (33.3%), and Week 4 - 6/13 (46.0%). No placebo subjects reported improvement at any timepoint. Biochemical response (≥50%reduction in u5-HIAA) and BM response (≥30% reduction in daily BMs for 2 weeks) were associated with reporting of adequate relief. For evaluable telotristat etiprate-treated patients, 9/16 (56%) experienced a biochemical response and 5/18 (28%) experienced a clinical (BM) response; no placebo subjects achieved either biochemical or clinical response. Conclusions: Treatment with telotristat etiprate was associated with decreases in u5-HIAA and BM frequency, and with self-reported relief of bowel related symptoms. Treatment in an extension phase with open-label telotristat etiprate is ongoing.

e14564 Background: Excess serotonin (5-HT) may contribute to gastrointestinal (GI) symptoms such as diarrhea in carcinoid syndrome (CS) patients. Telotristat etiprate, an oral serotonin synthesis inhibitor (SSI), is designed to reduce peripheral 5-HT levels and alleviate GI distress. Methods: This study evaluates the safety and tolerability of ascending doses (150 mg, 250 mg, 350 mg, and 500 mg tid) of telotristat etiprate in symptomatic CS patients, averaging ≥4 bowel movements (BMs)/day, either therapy-naïve or receiving somatostatin analogs. Secondary objectives include symptomatic response (change in: number of BMs/day, stool form/consistency, sensation of urgency to defecate, sensation/severity of nausea, global assessment of symptoms, assessment of abdominal pain/discomfort, reduction of cutaneous flushing episodes), and assessment of plasma drug concentrations, pharmacokinetics, and pharmacodynamics (urinary 5-hydroxyindolacetic acid [u5-HIAA] and blood 5-HT). All patients began dosing at 150 mg. Dose will be increased following 2 weeks of therapy with no dose-limiting toxicity. If dose-limiting toxicities occur, the dose will be reduced to prior level. Treatment will continue at the individual maximum-tolerated dose for 4 weeks; patients may elect to continue in an extension phase. Results: As of 1/2012, 13 patients, refractory to octreotide LAR have enrolled and been treated with telotristat etiprate. Eight (8) of 9 patients have completed the 12-week ascending dose study and 6 of 6 eligible patients have enrolled into the long-term extension, up to 72 weeks; 4 more patients are eligible for the long-term extension. Mean age: 63 years (range 51-81), mean BMs at baseline: 6.0 (range 4.7-8.5) for the 9 patients. Upon completion of 12 weeks of dosing, 7 of 9 patients (78%) had sustained reductions of ≥30% in BMs/day. All 7 of these patients had multiple assessments indicating ≥50% BM reductions) during the 6 weeks while on their highest dose. No major safety issues were detected. Conclusions: Telotristat etiprate produced biochemical and clinical responses/benefit in CS.

312 Background: Diarrhea associated with carcinoid syndrome (CS) has been attributed to tumor production of serotonin. Telotristat etiprate, (LX1032, LX1606), is an oral inhibitor of peripheral serotonin synthesis. This study explored the safety, tolerability, and efficacy of telotristat etiprate in carcinoid patients with octreotide-refractory diarrhea. Methods: Carcinoid patients with >4 bowel movements (BM)/day on octreotide were randomized 3:1 to receive telotristat etiprate or placebo. Patients enrolled in sequential, escalating dose cohorts of 150, 250, 350, or 500 mg tid, followed by a 500 mg tid expansion cohort. Patients were followed for toxicity, 24-hr urinary 5-HIAA (u5-HIAA) secretion, BM frequency, and self-reported relief of bowel-related symptoms. Subjects were asked “In the past 7 days, have you had adequate relief of your carcinoid syndrome bowel complaints such as diarrhea, urgent need to have a bowel movement, abdominal pain or discomfort?” Responses (yes or no) were analyzed as categorical variables. Results: 16 patients enrolled in the 4 escalating dose cohorts and 7 in the expansion cohort; 18 on telotristat etiprate and 5 on placebo. Median age was 62 yrs with a mean 6.2 BMs/day (range 4-10). AEs included primarily mild-moderate diarrhea, nausea, and abdominal discomfort. In treated subjects, adequate relief was reported as follows: Week 1 – 6/18 (33.3%), Week 2 – 5/16 (31.3%), Week 3 - 5/15 (33.3%), and Week 4 – 6/12 (50.0%). No placebo subjects reported improvement at any timepoint. Biochemical response (>50%reduction in u5-HIAA) and BM response (>30% reduction in daily BM for 2 weeks) were associated with reporting of adequate relief. For evaluable telotristat etiprate-treated patients, 9/16 (56%) experienced a biochemical response and 5/18 (28%) experienced a clinical (BM) response; no placebo subjects achieved either biochemical or clinical response. Conclusions: Treatment with telotristat etiprate was associated with decreases in u5-HIAA and BM frequency, and with self-reported relief of bowel related symptoms. Treatment in an extension phase with open-label telotristat etiprate is ongoing.

TPS168 Background: Carcinoid tumors are associated with serotonin (5-HT) secretion. High levels of serotonin are thought to contribute to the flushing, diarrhea, and abdominal discomfort observed i...

e13543 Background: Carcinoid syndrome (CS) occurs when metastatic carcinoid tumors secrete large amounts of serotonin (5-HT) and other bioactive substances into systemic circulation causing a varie...