Introduction

The purpose of this prospective study was to evaluate the toxicity and efficacy of a dose-intensified adjuvant doxorubicin protocol in canine splenic hemangiosarcoma.

Methods

Inclusion criteria required a histopathological diagnosis, complete staging (stage I, II and III without extra-abdominal metastasis), physical examination (PE), chest x-rays (CXR), abdominal ultrasound (AUS), echocardiography and complete bloodwork. Data collected included clinical variables at each visit, drug doses, adverse events (AE) (VCOG-CTCAE), median progression free survival (PFS) and overall survival (OS).

Doxorubicin was administered at 30 mg/m² or 1 mg/kg (<15 kg), every 10 days, for five total administrations, with maropitant at 2 mg/kg/day PO for four days. Echocardiography, AUS and CXR were repeated every two administrations and every four months thereafter.

Results

Ten dogs were included, stage I (n=1), stage II (n=8), stage III (n=1). Six males and 4 females, average weight was 20.49 kg and average age of 11.1 years. Toxicity was mild with 13/17 grade I/II, and four grade III/IV AE, (gastrointestinal (n=8), hematological (n=8), cardiac (n=1)). One grade IV gastrointestinal AE resulted in protocol discontinuation. One of the three dogs living more than a year developed transient ventricular tachycardia grade I responsive to atenolol. Two dogs received the maximum planned dose intensity 3.6 mg/m²/day, seven had modifications because of weight (n=4) or AE (n=3), receiving 2.6 mg/m²/day and 3.1–3.4mg/m²/ day, respectively. The median PFS and OS were 173 and 275 days, respectively.

Conclusion

A dose-intensified every 10 days doxorubicin protocol was well tolerated with similar PFS and OS times reported previously although a larger population is necessary to evaluate its efficacy.