Safety evaluation of combination doxorubicin and toceranib phosphate (Palladia®) in tumour bearing dogs: a phase I dose-finding study.

Combination chemotherapy holds promise for improving outcomes in malignancy when compared with single-agent approaches. Care must be taken to avoid overlapping toxicity and to utilize agents with differing mechanisms of action. A phase I dose-finding trial was performed to determine the maximally tolerated dose (MTD) of a concurrent toceranib and doxorubicin (DOX) combination protocol where toceranib dose was maintained at or near 2.75 mg kg−1 by mouth every other day (PO EOD) while escalating DOX dosage. The dose-limiting toxicity was found to be neutropenia and the MTD of the combination was determined to be 25 mg m−2 of DOX q 21 days given concurrently with toceranib 2.75 mg kg−1 PO EOD. This combination was well tolerated with no excessive gastrointestinal toxicity nor novel adverse events (AEs) noted. Anti-tumour activity was observed in the majority of cases. This combination warrants further investigation in the context of phase II/III clinical trials to characterize efficacy and long-term AE profiles.