Pasireotide for the Medical Management of Feline Hypersomatotropism

BACKGROUND: Feline hypersomatotropism (HST) is a cause of diabetes mellitus in cats. Pasireotide is a novel multireceptor ligand somatostatin analog that improves biochemical control of humans with HST. HYPOTHESIS/OBJECTIVES: Pasireotide improves biochemical control of HST and diabetes mellitus in cats. ANIMALS: Hypersomatotropism was diagnosed in diabetic cats with serum insulin‐like growth factor‐1 (IGF‐1) concentration >1,000 ng/mL by radioimmunoassay and pituitary enlargement. METHODS: Insulin‐like growth factor 1 was measured and glycemic control assessed using a 12‐hour blood glucose curve on days 1 and 5. On days 2, 3, and 4, cats received 0.03 mg/kg pasireotide SC q12h. IGF‐1, insulin dose, and estimated insulin sensitivity (product of the area under the blood glucose curve [BGC] and insulin dose) were compared pre‐ and post treatment. Paired t‐tests or Wilcoxon signed rank tests were employed for comparison where appropriate; a linear mixed model was created to compare BGC results. RESULTS: Insulin‐like growth factor 1 decreased in all 12 cats that completed the study (median [range] day 1: 2,000 ng/mL [1,051–2,000] and day 5: 1,105 ng/mL [380–1,727], P = .002, Wilcoxon signed rank test). Insulin dose was lower on day 5 than on day 1 (mean reduction 1.3 [0–2.7] units/kg/injection, P = .003, paired t‐test). The product of insulin dose and area under the BGC was lower on day 5 than day 1 (difference of means: 1,912; SD, 1523; u × mg/dL × hours, P = .001; paired t‐test). No clinically relevant adverse effects were encountered. CONCLUSIONS: Short‐acting pasireotide rapidly decreased IGF‐1 in cats with HST and insulin‐dependent diabetes. The decrease in IGF‐1 was associated with increased insulin sensitivity.