Development of a Peripherally Restricted 5-HT2B Partial Agonist for Treatment of Pulmonary Arterial Hypertension

Figures

• 

  Figure 1. Design and Evaluation of VU6047534 (A) Radioligand binding assays for 5-HT2B, 5-HT2A and 5-HT2C subtypes for VU6047534 compared to SB204741 by Eurofins Panlabs Discovery Services (Taiwan) according to standard protocols. NC = not calculated; all % inhibition < 50. Details can be found in Supplemental Figure 1. (B) Comparison between the ratio of total brain concentration to total plasma concentration (Kp) for SB204741 and VU6047534 in C57BL/6 mice 15 minutes post administration (i.p.). Open circles are female mice and filled circles are male mice. Data presented as mean ± SEM and compared with unpaired t-test, ∗∗∗P < 0.001.

• 

  Figure 2. Targeting the 5-HT2B Receptor Prevents Elevated RVSP and Fulton Index in Experimental Pulmonary Arterial Hypertension (A) 5-HT2B ligands, SB204741 (SB) and VU6047534 (VU) , prevent right ventricular systolic pressure (RVSP) elevation compared with nondrug-treated mice exposed to Sugen-hypoxia. (B) SB204741 and VU6047534 prevent elevated Fulton Index in mice exposed to Sugen-hypoxia. (C to E) Animals exposed to Sugen-hypoxia have significantly more muscularized vessels (0- to 25-μm diameter) than normoxic control animals, and SB204741 and VU6047534 significantly reduce the number of partially and fully muscularized vessels in Sugen-hypoxia exposed animals. Data presented as mean ± SEM. ∗∗P < 0.01 and ∗∗∗P < 0.001 vs all other experimental groups; #P < 0.05 vs control and VU6047534 normoxia groups; and ‡P < 0.01 vs normoxia groups. All statistics analyzed with 2-way analysis of variance followed by Tukey post hoc test for multiple comparisons. HPF = high-powered field; LV = left ventricle; RV = right ventricle; S = septum; SMA = smooth muscle actin.

• 

  Figure 3. Targeting the 5-HT2B Receptor Attenuates Elevated RVSP and Elevated Fulton Index in Experimental Pulmonary Arterial Hypertension (A) 5-HT2B ligands, SB204741 and VU6047534, attenuate RVSP elevation compared with nondrug-treated mice exposed to Sugen-hypoxia. (B) SB204741 and VU6047534 prevent elevated Fulton Index in mice exposed to Sugen-hypoxia. (C to E) Animals exposed to Sugen-hypoxia have significantly more muscularized vessels (0 to <25-μm diameter) than normoxic control animals, and SB204741 and VU6047534 significantly reduces the number of partially, but not fully muscularized vessels in Sugen-hypoxia exposed animals. Data presented as mean ± SEM. ∗P < 0.05 and ∗∗∗∗P < 0.0001 vs all other experimental groups: #P < 0.05, ##P < 0.01, and ###P < 0.001 vs normoxia groups. All statistics analyzed with 2-way analysis of variance followed by Tukey post hoc test for multiple comparisons. Abbreviations as in Figure 2.

• 

  Figure 4. Next-Generation 5-HT2B Ligands for Human Translation VU6055320 is a robust substrate for P-glycoprotein−mediated efflux and is predicted to be highly restricted to the periphery in human subjects. aRadioligand binding assays for 5-HT2B, 5-HT2A, and 5-HT2C subtypes by Eurofins Panlabs Discovery Services (Taiwan) according to standard protocols. NC = not calculated; all % inhibition <50. bP-gp efflux rate (P-gp ER) data provided by Absorption Systems. Classification of brain penetration potential: high = P-gp ER <3.0; moderate = 10 > P-gp ER >3.0; low = P-gp ER >10.