Increasing chemo drug doses in dogs with multicentric lymphoma

Abstract

BACKGROUND: This study was performed to determine the ability to escalate drug doses in a 15-week CHOP protocol in dogs with multicentric lymphoma. HYPOTHESIS: We hypothesized that at least 50% of dogs could successfully be escalated in at least 1 drug. Secondary aims were to establish objective response rate (ORR), progression-free interval (PFI), and overall survival time (OST). ANIMALS: Thirty dogs with newly diagnosed multicentric lymphoma were prospectively treated with a 15-week CHOP protocol. METHODS: This was a prospective cohort study. Drug doses that did not cause dose-limiting adverse effects (AEs) were increased using a standardized escalation protocol. AEs and response were assessed using VCOG criteria. Serial blood samples were collected after the first dose of each drug for pharmacokinetic analysis. RESULTS: Of the 23 dogs with the opportunity to dose escalate, at least 1 drug was successfully escalated in 18 (78%). Vincristine was successfully escalated to 0.8 mg/mor higher in 11 dogs, cyclophosphamide to 300 mg/mor higher in 16 dogs, and doxorubicin to 35 mg/mor 1.4 mg/kg or higher in 9 dogs. Three of the 23 dogs (13%) were hospitalized at least once because of drug-induced AEs. Neutropenia was the most common dose-limiting toxicosis for all drugs. Peak doxorubicin concentrations were significantly lower in dogs where doxorubicin was successfully escalated. The objective response rate was 100%. The median progression free interval was 171 days. The median overall survival time was 254 days. CONCLUSIONS: Drugs in the CHOP protocol can often be escalated safely with manageable AEs.