Development of a targeted oral pharmacologic duodenal exclusion therapy for the treatment of metabolic diseases

Abstract

Type 2 diabetes (T2D) and obesity are chronic metabolic diseases with global morbidity and mortality. Decades of evidence from surgical and endoscopic procedures bypassing the duodenum underscore the duodenum's critical role in regulating glycemia and body weight. Although metabolic surgeries and endoscopic procedures are effective, their invasiveness, cost, and scalability limit patient access. We developed an orally administered mucin complexing polymeric (MCP) drug, designed to replicate duodenal exclusion physiology. MCPs, intended to have electrostatic and covalent cross-linkages with mucin glycoproteins, form extended network structures with resulting alteration of mucus barrier properties. Selective targeting of the duodenum is achieved via pH-based activation chemistry. Following screening for physiochemical properties, pharmacokinetics, and efficacy, GLY-200 emerged as the lead drug candidate replicating duodenal exclusion physiology with improved glycemia, reduced body weight, and modulation of gut hormones in rodent models. This targeted oral therapy holds promise for treatment of T2D and obesity by mimicking duodenal exclusion without the invasiveness of surgery or endoscopic procedures.

Fig. 1.. Schematic of oral polymeric drug capable of augmenting and enhancing the natural GI mucus barrier to emulate duodenal exclusion physiology.

Fig. 2.. Targeted and pH sensitive mucus complexation.

(A) Behavior of polymer with mucin solutions (1 wt %) was evaluated at different pH conditions to identify phase and appearance changes indicative of the formation of a polymer-mucin complex. (B) Mucin:polymer complex was quantified with a centrifuge assay to determine extended network barrier properties at different pH conditions (means ± SEM, n > 3). Significance is only shown between PAAn-CPBA and PAAn-FCPBA (****P ≤ 0.0001). (C) SPR sensogram identifies the binding behavior of polymer to mucin and evaluates the strength of the association following serial salt challenges (2 M NaCl) and (D) effective diffusivity (D_eff) of particles in mucus treated with 0.0, 0.1, 0.25, and 0.4 wt % polymer. Trajectories of at least 300 particles were analyzed for each experiment group, and three separate experiments were performed to account for mucus variability. *P ≤ 0.05.

Fig. 3.. Robust, dose-dependent complexation on ex vivo intestinal tissue.

(A) Macroscopic (5 cm by 5 cm) and microscopic images (8x magnification) of porcine tissue treated with GLY-200 or buffer visualize the GLY-200:mucus complex with an anionic dye, indigo carmine (complex retains indigo staining). Tissue was imaged before polymer or buffer addition, after incubation with dye, and after robust washing (n ≥ 4). Right: Two representative microscopic images (8x magnification) show tissues after washing. Scale bar, 0.5 cm. (B) IVIS images of porcine tissue (5 cm by 5 cm) treated with FITC–GLY-200 or FITC–Dextran 70k were taken before addition, after addition, and after robust washing, and (C) radiant efficiency from the IVIS images was measured and % retention is reported (n = 3).

Fig. 4.. Intestinal transit and distribution of GLY-200.

(A) Fasted rats were orally administered GLY-200 or Dextran 70k (80 mg per rat), and the GI tract was collected and imaged at 0.5, 1, 2, 4, and 8 hours to visualize polymer transit (n ≥ 2). (B) Sections of the proximal duodenum were collected and processed by IHC (4.7x and 17.3x magnification). The duodenal cross section shows colocalization of the polymer (green: GLY-200–FITC) and mucus (red: anti-MUC2;). DNA visualized with DAPI (blue).

Fig. 5.. A PK, mass balance, and tissue distribution of GLY-200.

(A) Whole body autoradioluminogram showing tissue distribution of radioactivity in rodent at 4 and 48 hours following an oral dose of [14C]-GLY-200 at 80 mg per animal (n = 1 per sex per time point). (B and C) Recovery of administered GLY-200 equivalents in (B) rodent and (C) canine following an oral dose of [14C]-GLY-200 (n ≥ 3).

Fig. 6.. Postprandial glucose and insulin response following oral GLY-200 administration in rodent models.

A standardized oral glucose tolerance test was performed on GK (A and B) and ZDF (C to F) rats. (A) Blood glucose and (B) iAUC_0–180 response following a single dose of GLY-200 (120 and 180 mg per rat) in GK rats (n = 6 to 7). [(C) and (D)] Blood glucose and [(E) and (F)] insulin response in ZDF rodents receiving chronic GLY-200 treatment (60 and 120 mg per rat per day, n = 14 per group) for [(C) and (E)] 4 weeks and [(D) and (F)] 8 weeks. Means ± SEM, ****P ≤ 0.0001, ***P ≤ 0.001, **P ≤ 0.01, and *P ≤ 0.05.

Fig. 7.. BW reduction, adiposity, and hormonal signals following once daily dosing of GLY-200 for 8 weeks in the DIO rat model.

(A) GLY-200 resulted in significant reductions in BW gain by day 12 that further improved through day 51 (*P < 0.05 and **P < 0.01). N = 11 to 12 per group. Data are means ± SEM (A) and median (B), (C) mWAT, (D) eWAT, (E) adipocyte area, (F) gastric weight, (G) active GLP1, and (H) PYY evaluated in a subset of the animals (n ≥ 7). Data are means ± SEM. ***P ≤ 0.001, **P ≤ 0.01, and *P ≤ 0.05.