Lobaplatin as an adjuvant chemotherapy to surgery in canine appendicular osteosarcoma: a phase II evaluation

Canine osteosarcoma, the most common bone tumor in dogs, is a well-established, naturally-occurring animal model for human OS. The aim of this study was to evaluate the clinical and hematological side-effects and to assess the efficacy of lobaplatin chemotherapy in dogs with appendicular osteosarcoma as an adjuvant therapy to surgical resection. Twenty-eight dogs without systemic signs of disease were treated with surgical resection of the tumor and adjuvant lobaplatin chemotherapy at a dose of 35 mg/m2, i.v., once every three weeks, for a maximum of 4 doses. Clinical signs of toxicosis were uncommon and consisted mainly of vomiting and depression. Hematological signs of toxicoses were common 7 to 10 days after lobaplatin chemotherapy and consisted of thrombocytopenia, leukopenia and neutropenia. All the signs were transient and most disappeared within three weeks of lobaplatin administration. A one-year disease-free fraction of 21.8% and a one-year survival fraction of 31.8% were calculated. Multivariate Cox regression analyses showed that a high histological tumor grade and presence of metastasis in the tumor vessels were associated with significantly shorter disease-free interval and survival time. Also, an increased pretreatment plasma alkaline phosphatase level at first presentation and a high histological level of tumor necrosis were associated with a shorter survival interval. Lobaplatin was easy to administer as an i.v. bolus injection at a three-week interval in dogs without the need for pretreatment infusions.