Evaluation of P-glycoprotein expression in feline lymphoma and correlation with clinical outcome.

P-glycoprotein (Pgp) is a transmembrane protein pump involved in drug resistance in canine and human lymphoma. There are no published clinical studies evaluating Pgp expression in feline lymphoma. The purpose of this study is to evaluate the level of Pgp expression in feline lymphoma and correlate it with clinical outcome. Two human Pgp monoclonal antibodies, C219 and C494, were used to detect Pgp expression in tissue samples from 63 cats with lymphoma. Demographic results appear comparable to recently published feline lymphoma studies. The Kaplan-Meier median remission and survival times were 164 and 571 days, respectively. Fourteen cats had positive expression of Pgp using MAb C219, and 40 were positive with C494. Variables statistically associated with survival included bone marrow involvement, stage, substage, and use of radiation therapy as a part of treatment. Pgp expression as assessed by MAb C219 and C494 is not predictive of remission or survival time in cats with lymphoma.