SU5416 plus hypoxia but not selective VEGFR2 inhibition with cabozantinib plus hypoxia induces pulmonary hypertension in rats: potential role of BMPR2 signaling

Abstract

Introduction: SU5416 plus chronic hypoxia causes pulmonary arterial hypertension (PAH) in rats and is assumed to occur through VEGFR2 inhibition. Cabozantinib is a far more potent VEGFR2 inhibitor than SU5416. Therefore, we hypothesized that cabozantinib plus hypoxia would induce severe PAH in rats. Methods: Cell proliferation and pharmacokinetic studies were performed. Rats were given SU5416 or cabozantinib SC or via osmotic pump and kept hypoxic for 3 weeks. Right ventricular systolic pressure (RVSP) and hypertrophy (RVH) were evaluated at day 14 and 28 following removal from hypoxia. RV fibrosis was evaluated with Picro-Sirius Red staining. Kinome inhibition profiles of SU5416 and cabozantinib were performed. Inhibitor binding constants of SU5416 and cabozantinib for BMPR2 were determined and Nanostring analyses of lung mRNA were performed. Results: Cabozantinib was a more potent VEGFR inhibitor than SU5416 and had a longer half-life in rats. Cabozantinib SC plus hypoxia did not induce severe PAH. RVSP at 14 and 28d post-hypoxia was 36.8 ± 2.3 mmHg and 36.2 ± 3.4 mmHg, respectively, versus 27.5 ± 1.5 mmHg in normal controls. For cabozantinib given by osmotic pump during hypoxia, RVSP was 40.0 ± 3.1 mmHg at 14d and 27.9 ± 1.9 mmHg at 28d post-hypoxia. SU5416 plus hypoxia induced severe PAH (RVSP 61.9 ± 6.1 mmHg and 64.9 ± 8.4 mmHg at 14d and 28d post-hypoxia, respectively). Cabozantinib induced less RVH (RV/(LV+IVS) at 14d post-hypoxia compared to SU5416. RV fibrosis was more extensive in the SU5416 groups compared to the Cabozantinib groups. SU5416 (but not cabozantinib) inhibited BMPR2. Nanostring analyses showed effects on pulmonary gene expression of BMP10 and VEGFR1 in the SU5416 28 day post hypoxia group. Conclusion: Selective VEGFR2 inhibition using cabozantinib plus hypoxia did not induce severe PAH. Severe PAH due to SU5416 plus hypoxia may be due to combined VEGFR2 and BMPR2 inhibition.

PGC-1α–mediated angiogenesis prevents pulmonary hypertension in mice

“…This newly identified angiogenic response appears to be essential for the adaptation to acute hypoxic exposure and maintenance of EC function but was suppressed after treatment with SU5416, a VEGFR2 TKI. It has been shown that cabozantinib, which is a more potent VEGFR2 TKI, could not induce severe PH in hypoxic rats and SU5416 might exert a pathogenic effect via combined VEGFR2 and BMPR2 signaling inhibition ( 10 ) and/or activation of aryl hydrocarbon receptor signaling ( 24 ) under hypoxic conditions. However, in the present study, administration of cabozantinib to hypoxic mice exacerbated Hx-PH with suppression of Ppargc1a and Vegfa expression as well as SU5416.…”

“…Cabozantinib was purchased from LC Laboratories and suspended using sonication in a mixture of 0.5% carboxymethylcellulose sodium, 0.9% sodium chloride, 0.4% polysorbate 80, and 0.9% benzyl alcohol in deionized water. CabHx mice were injected once weekly with cabozantinib at 20 mg/kg BW during hypoxic exposure ( 10 ). Baicalin (CAS 21967-41-9) was purchased from Merck KGaA.…”

“…In addition, SU5416, a VEGFR2-tyrosine kinase inhibitor (TKI), combined with Hx induced severe PH with neointimal occlusive lesions in rats (SuHx) ( 9 ), suggesting that VEGF is protective in the context of PH. However, treatment with cabozantinib, a more potent VEGFR2-TKI than SU5416, combined with Hx did not induce severe PH in rats, suggesting that VEGFR inhibition may not be critically involved in the development of severe PH in rats ( 10 ).…”

Experimental animal models of pulmonary hypertension: Development and challenges

“…However, SU5416 can specifically bind to ECs, enriched in the membrane and thence slowly released into the cytoplasm, which ensures long‐term inhibition of VEGFR 24 . Loss of EC growth signal, inflammation and oxidative stress due to inhibition of VEGFR, TGF‐β/BMP/Smad, Hif‐1α, mitogen‐activated protein kinase (MAPK), aryl hydrocarbon receptor (AhR) and other signaling pathways are involved in the regulation of the SU5416/hypoxic (SuHx) PH model 21,25,26 . Sharing other hallmarks (concentric laminar and plexiform lesions) of human PAH, the rodent SuHx PH model is regarded as a more appropriate preclinical model of occlusive PAH than the CHPH models, particularly for genetic modification or long‐term intervention 27‐29 …”

Sugen, hypoxia and the lung circulation

“…In addition, Sitapara et al. reported that Sugen 5416 affects BMPRII signaling, 16 providing yet another possible explanation for the development of PAH like vascular lesions after the double challenge of Sugen and hypoxia.…”