P32/98 (hemifumarate)

Ki: 126 nM

P32/98 (hemifumarate) is an inhibitor of DPP IV.

Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) are responsible for >50% of nutrient-stimulated insulin secretion. After being released into the circulation, GIP and GLP-1 are quickly inactivated by the circulating enzyme dipeptidyl peptidase IV (DPP IV).

In vitro: P32/98 was found to be able to block adipogenesis dose-dependently, starting at the concentration of 100 μM, and P32/98 could completely block adipogenesis in 3T3-L1 cell line at 500 μM concentration. In addition, the inhibitory effects of P32/98 was further confirmed by detecting the expression of adipocyte markers at the end of differentiation [1].

In vivo: In previou animal study, two groups of fa/fa Zucker rats were orally treated twice daily for three months with P32/98 at 20 mg/kg/day and monthly oral glucose tolerance tests (OGTTs) were conducted after drug washout. Results showed that after 12 weeks of P32/98 treatment, the peak OGTT blood glucose values in the treated rats averaged 8.5 mmol/l less than in the controls. In addition, the concomitant insulin resulted in an increased early-phase insulin response in the treated group. Moreover, in response to an 8.8 mmol/l glucose perfusion, pancreata from controls showed no increase in insulin secretion, while pancreata from P32/98-treated animals had a 3.2-fold rise in insulin secretion [2].

Clinical trial: Up to now, P32/98 is still in the preclinical development stage.

References:
1.  Han R, Wang X, Bachovchin W, Zukowska Z, Osborn JW. Inhibition of dipeptidyl peptidase 8/9 impairs preadipocyte differentiation. Sci Rep. 2015 Aug 5;5:12348.
2.  J. A. Pospisilik, S. G. Stafford, H. U. Demuth, et al. Long-term treatment with the dipeptidyl peptidase IV inhibitor P32/98 causes sustained improvements in glucose tolerance, insulin sensitivity, hyperinsulinemia, and β-cell glucose responsiveness in VDF (fa/fa) zucker rats. Diabetes 51, 943-950 (2002).