Hematologic Responses to Molidustat in Cats with Anemia of Heterogeneous Etiology: A Retrospective Descriptive Study

Molidustat, an oral hypoxia-inducible factor prolyl hydroxylase inhibitor, is approved for nonregenerative anemia associated with chronic kidney disease (CKD) in cats but is also used for anemia of other causes. This retrospective, single-center study described the hematologic response to molidustat in 39 cats with anemia of heterogeneous etiology and identified factors that complicate attribution of improvement to the drug. Response was defined as a hematocrit (HCT) increase of ≥4 percentage points from baseline at the complete blood count closest to day 28 (days 14-45), without transfusion to treat anemia. Molidustat was used outside the approved indication in 33 cats (84.6%). Seventeen cats (43.6%) had a response-window measurement; they had a longer treatment span and differed in etiology and concurrent treatment from non-evaluable cats. Among these 17 cats, 12 (70.6%; 95% CI 46.9-86.7%) met the response criterion; sensitivity analyses specified before formal analysis gave 70.6-75.0% and post hoc attribution analyses 29.4-50.0%. In 7 of the 12 responders, darbepoetin or transfusion preceded the qualifying measurement, or it was obtained more than 7 days after the last dose. These data describe clinical use but do not establish effectiveness outside CKD-associated anemia.