ABSTRACT Advanced carcinomas in dogs present significant therapeutic challenges with limited treatment options and poor prognoses. Sorafenib, a multi‐kinase inhibitor targeting RAF and receptor tyrosine kinases, has demonstrated antitumor activity and tolerability in preclinical veterinary studies; however, clinical data remain limited. This prospective, open‐label cohort study evaluated the tolerability and clinical efficacy of oral sorafenib (6 mg/kg once daily) in 24 dogs with cytologically or histologically confirmed unresectable, recurrent, or metastatic carcinomas. Tumour response was assessed using RECIST criteria, and adverse events were graded according to VCOG‐CTCAE v2.0. Stable disease at 1 month was observed in 14 of 18 evaluable dogs (77.8%), yielding an overall clinical benefit rate of 58.3%. Median time to progression and overall survival were 51 days (95% CI, 14–115) and 65 days (95% CI, 49–143), respectively. Dogs presenting with lameness ( n = 7) showed significantly longer time to progression and overall survival than those without ( p < 0.01). Adverse events occurred in 9 of 24 dogs (37.5%), primarily mild lameness (29%) and gastrointestinal signs. Weight gain at 1 month, observed in 66.7% of dogs, was significantly associated with clinical benefit ( p = 0.005; OR = 45.0; 95% CI, 1.8–1127.7). Sorafenib was well tolerated and provided measurable clinical benefit in dogs with advanced carcinomas. Lameness may represent a prognostic biomarker, and weight gain may reflect a favourable clinical response. These findings support further investigation of sorafenib and other tyrosine kinase inhibitors in veterinary oncology.
Kim et al. (Fri,) studied this question.