Dermatological Adverse Events Associated With Lapatinib Treatment in Dogs With Urothelial Carcinoma: A Retrospective Study.

Abstract

BACKGROUND: Lapatinib is widely used in human oncology; however, dermatological adverse events (DAEs) are common and have been correlated with treatment efficacy. In veterinary medicine, lapatinib use in combination with piroxicam has been shown to be effective in treating canine urothelial carcinoma (UC); however, the incidence and prognostic significance of DAEs in dogs remain unknown. OBJECTIVE: To evaluate the DAEs in dogs with UC treated with lapatinib and piroxicam. ANIMALS: Eighty-five dogs with UC were treated with lapatinib/piroxicam and 42 were treated with piroxicam alone. MATERIALS AND METHODS: This retrospective cohort study evaluated dogs diagnosed with UC and treated with lapatinib and piroxicam, and those treated with piroxicam alone. Relevant data were extracted from the medical records. The DAEs were assessed using the Veterinary Cooperative Oncology Group Common Terminology Criteria for Adverse Events and Naranjo algorithm. The log-rank test and Cox proportional hazards model were used to assess progression-free survival (PFS). RESULTS: DAEs occurred in 31.8% of the dogs in the lapatinib/piroxicam group, with alopecia and hyperpigmentation being the most common. In the piroxicam group, DAEs were observed in 7.1% of dogs. The relative risk of developing DAEs in the lapatinib/piroxicam group was 4.4 (p&#x2009;<&#x2009;0.01). In the lapatinib/piroxicam group, DAEs were associated with a longer PFS (p&#x2009;<&#x2009;0.03). The Cox proportional hazards model identified DAEs as independent prognostic factors for improved PFS (hazard ratio, 0.52, p&#x2009;<&#x2009;0.05). CONCLUSIONS AND CLINICAL RELEVANCE: Lapatinib treatment in dogs induces DAEs, which serve as biomarkers of lapatinib efficacy in canine UC.