Abstract
BackgroundEffective treatment options for inoperable, metastatic, or recurrent canine pheochromocytomas are lacking. In humans, specific germline mutations exist that drive the development of pheochromocytomas. Pharmaceutical blockade of these abnormalities with small molecule inhibitors are an effective treatment strategy. Similar mutations may exist in the dog, and thus, treatment with similar small molecule inhibitors may provide a survival advantage. The purpose of this study was to assess the role of toceranib phosphate in the treatment of inoperable, metastatic, or recurrent canine pheochromocytomas.ResultsRetrospectively, medical records of dogs that had a diagnosis or suspect diagnosis of a pheochromocytoma were reviewed for information regarding response to toceranib phosphate and overall outcome. Five dogs were identified that fit the inclusion criteria. All five experienced clinical benefit (1 partial response, 4 stable disease). Progression-free interval (PFI) for the dog with the partial response was 61 weeks. PFI for the two dogs with stable measurable disease were 36 weeks and 28 weeks. PFI in the two dogs with stable metastatic disease were at least 11 weeks and 18 weeks.ConclusionsBased on this limited series of dogs, the results suggest that toceranib may have biological activity in dogs with primary and metastatic pheochromocytomas. Larger studies are needed to define the use and response to toceranib in dogs with gross, microscopic, and metastatic pheochromocytoma.
Highlights
Effective treatment options for inoperable, metastatic, or recurrent canine pheochromocytomas are lacking
For dogs with measurable disease, as in previous publications describing the use of toceranib in dogs, clinical benefit (CB) was determined by best response to therapy and was defined as a complete response (CR) or partial response (PR) of any duration, or stable disease (SD) of at least ten weeks in duration [30]
Five dogs were identified that fit the inclusion criteria (Table 1)
Summary
Effective treatment options for inoperable, metastatic, or recurrent canine pheochromocytomas are lacking. Specific germline mutations exist that drive the development of pheochromocytomas. Pharmaceutical blockade of these abnormalities with small molecule inhibitors are an effective treatment strategy. Anesthesia and surgical removal of an adrenal tumor is a high-risk procedure, carrying an overall 51% postoperative complication rate, which increases to 60% in dogs with PC [4]. These complications can include significant blood pressure variations, tachyarrhythmias, intraoperative hemorrhage, and intraoperative death [3, 4]. Vascular invasion into the caudal vena cava, reported in up to 82% of cases, [4, 5] complicates the surgical approach, but the impact on survival in these cases is unclear [4,5,6]
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