Cyclooxygenase-2 inhibition prevents renal toxicity but not hypertension during sunitinib treatment

Background: Anticancer angiogenesis inhibitors cause hypertension and renal injury. Previously we observed in rats that high-dose aspirin (capable of blocking cyclooxygenase (COX)-1 and-2) was superior to low-dose aspirin (blocking COX-1 only) to prevent these side-effects during treatment with the angiogenesis inhibitor sunitinib, suggesting a role for COX-2. High-dose aspirin additionally prevented the rise in COX-derived prostacyclin (PGI₂). Therefore, we studied the preventive effects of selective COX-2 inhibition and the hypothesized contributing role of PGI₂ during angiogenesis inhibition. Methods: Male WKY rats received vehicle, sunitinib ((SU), 14 mg/kg/day) alone or combined with COX-2 inhibition (celecoxib, 10 mg/kg/day) or a PGI₂ analogue (iloprost, 100 μg/kg/day) for 8 days (n = 8–9 per group). Mean arterial pressure (MAP) was measured via radiotelemetry, biochemical measurements were performed via ELISA and vascular function was assessed via wire myography. Results: SU increased MAP (17±1mmHg versus 3±1mmHg after vehicle on day 4, P < 0.002), which could not be significantly blunted by celecoxib (+12±3mmHg on day 4, P = 0.247), but was temporarily attenuated by iloprost (treatment days 1 + 2 only). Urinary PGI₂ (996 ± 112 versus 51 ± 11ng/24h after vehicle, P < 0.001), but not circulating PGI₂ increased during SU, which remained unaffected by celecoxib and iloprost. Celecoxib reduced sunitinib-induced albuminuria (0.36 ± 0.05 versus 0.58 ± 0.05mg/24h after SU, P = 0.005). Wire myography demonstrated increased vasoconstriction to endothelin-1 after SU (Emax P = 0.005 versus vehicle), which remained unaffected by celecoxib or iloprost. Conclusion: Selective COX-2 inhibition ameliorates albuminuria during angiogenesis inhibition with sunitinib, which most likely acts independently of PGI₂. To combat angiogenesis inhibitor-induced hypertension, dual rather than selective COX-1/2 blockade seems preferential.