Lokivetmab therapy for pruritus in a dog with cutaneous mastocytosis

Abstract

Background Cutaneous mastocytosis (CM) is a rare disease of dogs characterized by rash, pruritus and proliferation of mast cells in the skin. Oral H1 antihistamines are recommended as the treatment to control pruritus. Hypothesis/Objective To describe the effective treatment of pruritus associated with CM with lokivetmab in one dog. Animal A 4‐year‐old, spayed female cross‐bred dog presented with severely pruritic, erythematous to pigmented macules and papules involving the ventral abdomen, interdigital skin, perivulval area and both pinnae; the pruritus had been unresponsive to treatment with antihistamines, prednisone and ciclosporin. Methods and materials Complete blood count and serum biochemistry, abdominal ultrasound, blood smear and skin cytological evaluation, PCR, histopathological and immunohistochemical examination of skin biopsies. Results Skin cytological evaluation revealed high numbers of uniform, heavily granulated mast cells; histopathological findings showed focal dermal proliferations of well‐differentiated, uniform mast cells consistent with a low‐grade mast cell tumour (MCT). Clinical staging revealed that the disease was confined to the skin. Mutations of c‐kit exon 8 and 11 were not detected. Treatment was initiated with anti‐canine‐interleukin (IL)‐31 monoclonal antibody lokivetmab; antihistamines were continued. The dog's pruritus resolved within seven days and was maintained in remission over 15 months with once monthly lokivetmab injections; the skin lesions improved but did not resolve. Conclusion and clinical importance Lokivetmab treatment was effective in resolving and maintaining pruritus remission in this dog with widespread cutaneous mast cell disease. Whether CM in dogs represent a separate entity that should be distinguished from a low‐grade MCT requires further investigation.

A case of cutaneous bullous mastocytosis in a Yorkshire terrier puppy

“…The clinical and histopathological findings in this case are consistent with a diagnosis of CBM, which is a subtype of DCM that has not been described previously in dogs. While juvenile mast cell disease (MPCM or previously termed urticaria pigmentosa-like) has been described in young dogs, 5,6 and Darier's sign was found positive, 5,6 none had bullous lesions and Darier's sign, as in this case.…”

A masked, randomised clinical trial evaluating the efficacy and safety of lokivetmab compared to saline control in client‐owned dogs with allergic dermatitis

“… 6 , 7 , 8 The mode of action of lokivetmab combined with postmarketing studies on its use in pruritic skin diseases other than cAD, have suggested that it could be a valuable treatment alternative for dogs suffering from other allergic dermatoses. 9 , 10 The objective of the study, therefore, was to demonstrate the efficacy and safety of lokivetmab for the treatment of pruritus associated with allergic dermatitis of various aetiologies in dogs.…”

Serum concentrations of IL‐31 in dogs with nonpruritic mast cell tumours or lymphoma

“…IL‐31 concentration was significantly higher in human patients with progressive disease than in patients without progression 28 . Reduction of pruritus was described in a dog with pruritic mastocytosis after using lokivetmab, a monoclonal antibody against canine IL‐31 29 . In humans, mast cells were described as a source of IL‐31 30 as well as the target of IL‐31 exposure in people with pruritus, 8 similar to what was described in patients with carcinoma of the endometrium 2 .…”

“…28 Reduction of pruritus was described in a dog with pruritic mastocytosis after using lokivetmab, a monoclonal antibody against canine IL-31. 29 In humans, mast cells were described as a source of IL-31 30 as well as the target of IL-31 exposure in people with pruritus, 8 similar to what was described in patients with carcinoma of the endometrium. 2 In our study, dogs with MCT had one or more tumours of various sizes without distant metastases, three dogs had metastases in regional lymph nodes and one patient had mastocytosis.…”