Evaluation of the adverse event profile and pharmacodynamics of toceranib phosphate administered to dogs with solid tumors at doses below the maximum tolerated dose.
BACKGROUND
The receptor kinase inhibitor toceranib phosphate (Palladia) was approved for use in dogs in 2009 using a dose of 3.25 mg/kg administered every other day. Preliminary data suggests that lower doses of toeceranib may be associated with a reduced adverse event profile while maintaining sufficient drug exposure to provide biologic activity. The purpose of this study was to determine the Cmax of toceranib in dogs with solid tumors receiving 2.5-2.75 mg/kg every other day and to document the adverse events associated with this dose rate. Secondary objectives included determination of plasma VEGF concentrations in treated dogs and response to therapy.


RESULTS
Dogs with solid tumors were administered toceranib at an intended target dose ranging from 2.5-2.75 mg/kg every other day and plasma samples were obtained for analysis of toceranib and VEGF plasma concentrations on days 0, 7, 14 and 30 of the study at 6 and 8 hours post drug administration. Additionally, plasma samples were obtained at 0, 1, 2, 6, 8, and 12 hours from dogs on day 30 for confirmation of Cmax. Response to therapy was assessed using standard RECIST criteria and adverse events were characterized using the VCOG-CTCAE. Toceranib administered at doses between 2.4-2.9 mg/kg every other day resulted in an average 6-8 hr plasma concentration ranging from 100-120 ng/ml, well above the 40 ng/ml concentration associated with target inhibition. Plasma VEGF concentrations increased significantly over the 30 day treatment period indicating that VEGFR2 inhibition was likely achieved in the majority of dogs. The lower doses of toceranib used in this study were associated with a substantially reduced adverse event profile compared to the established label dose of 3.25 mg/kg EOD.


CONCLUSIONS
Doses of toceranib ranging from 2.4-2.9 mg/kg every other day provide drug exposure considered sufficient for target inhibition while resulting in an adverse event profile substantially reduced from that associated with the label dose of toceranib. This lower dose range of toceranib should be considered for future use in dogs with cancer.
Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA. cheryl.london@cvm.osu.edu.
Luis Feo
LF
Bernabe
Roberta
R
Portela
Sandra
S
Nguyen
William C
WC
Kisseberth
Michael
M
Pennell
Mark F
MF
Yancey
Cheryl A
CA
London
D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use; D004283:Dog Diseases / Q000188:drug therapy*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D007211:Indoles / Q000008:administration & dosage / Q000009:adverse effects* / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use; D008297:Male; D009369:Neoplasms / Q000188:drug therapy / Q000662:veterinary*; D011758:Pyrroles / Q000008:administration & dosage / Q000009:adverse effects* / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use; D042461:Vascular Endothelial Growth Factor A / Q000097:blood / Q000378:metabolism
D000970:Antineoplastic Agents; D007211:Indoles; D011758:Pyrroles; D042461:Vascular Endothelial Growth Factor A; C464577:toceranib phosphate