Efficacy and adverse events of anthracycline and propranolol combination in five dogs with stage 3 hemangiosarcoma.

Background: Canine hemangiosarcoma (HSA), which originates from endothelial cells, is one of the most common malignant neoplasms that frequently develop metastatic lesions. Although anthracycline-based HSA treatment strategies have been widely investigated, reliable therapy for dogs with clinically advanced-stage HSA (stage 3 HSA) has not been established yet. Recently, several studies have demonstrated that propranolol, a beta-adrenergic receptor antagonist, exhibits anti-tumor effects against tumors originating from vascular endothelial cells, indicating the possibility that propranolol is a candidate adjunctive agent for anthracycline-based therapy in dogs with stage 3 HSA. This study aimed to evaluate the clinical efficacy and adverse events (AEs) of anthracycline and propranolol combination in stage 3 HSA-affected dogs. Case Description: We retrospectively investigated five dogs diagnosed with stage 3 HSA which were administered with both anthracycline and propranolol during the same period between January 2020 and August 2021. Clinical benefit was observed in four of five HSA dogs (one of complete response, one of partial response, and two of stable disease) with gross metastatic lesions by anthracycline and propranolol combination. Notably, some or all of the metastatic lesions were reduced in two cases. In all five dogs administered with anthracycline and propranolol combination, no serious and irreversible AEs were observed. Conclusion: Our findings demonstrate the efficacy and safety of anthracycline and propranolol combination in stage 3 HSA-affected dogs. Further studies are needed to establish treatment protocols based on anthracycline and propranolol combination for dogs with advanced HSA.