Use of imiquimod 5% cream (Aldara™) in cats with multicentric squamous cell carcinoma in situ: 12 cases (2002–2005)*

Abstract

Multicentric squamous cell carcinoma in situ (MSCCIS) is a variant of squamous cell carcinoma in cats, commonly referred to as Bowen's-like disease. Imiquimod 5% cream (Aldara) is a novel immune response modifier (IRM) that has been reported as a successful treatment for Bowen's disease in humans. The purpose of this study was to describe clinical findings, treatment protocols and survival in cats with MSCCIS treated with imiquimod 5% cream and to examine the effects of imiquimod 5% cream in cats with MSCCIS. The expression of papillomavirus group-specific antigen in the study population was also determined. From review of medical records, 12 cats were identified with a histologic diagnosis of MSCCIS and treatment with imiquimod 5% cream. Initial lesions responded to imiquimod 5% cream in all cats. Most cats (75%) developed new lesions. New lesions also responded to imiquimod 5% cream in all cats treated. Five cats (41%) had side effects suspected to be associated with the use of imiquimod 5% cream, including local erythema (25%), increased liver enzymes and neutropenia (8%), and partial anorexia and vomiting (8%). Kaplan-Meier median treatment duration and median survival time probabilities for cats in this study were 1189 days, respectively. A time to failure model was generated as many cats were censored from analysis well before the aforementioned projected median. This model resulted in a shorter median survival time of 243 days. No patient-related, tumour-related or treatment-related prognostic variables were identified. No expression for papilloma group-specific antigen was found. Imiquimod 5% cream appears to be well tolerated in the majority of cats, and further studies are warranted to further examine its usefulness in cats with this disease.

The detection of Felis catus papillomavirus 3 DNA in a feline bowenoid in situ carcinoma with novel histologic features and benign clinical behavior

“…Although the clinical behavior of BISCs is variable, the slow lesion progression over a long period of time is unusual. 3,4 The cat in our report developed a single BISC and did not develop any additional lesions. In contrast, multiple lesions were consistently present in a previous study of 19 cats with BISCs.…”

Topical imiquimod in the treatment of two cutaneous melanocytomas in a dog

“…Imiquimod was used (daily to three times weekly) to treat multicentric squamous cell carcinoma in situ (Bowen’s disease) in 12 cats, with complete clinical resolution in all cases, although new lesions developed in different areas in nine of the treated cats 21 . The new lesions also resolved clinically with imiquimod treatment.…”

Immunotherapy in Veterinary Oncology

“…Twelve cats with Bowen-like disease were treated topically with imiquimod 5% cream and initial as well as all subsequent new lesions responded in all cats. 35 An additional cat (with pinnal actinic keratoses and squamous cell carcinoma) and dog with cutaneous melanocytomas have subsequently been reported to have been successfully treated with topical imiquimod 5% cream. 36,37 It seems, therefore, that imiquimod 5% cream is well tolerated, and further studies are warranted to further examine its usefulness in cats and dogs with other skin tumors that are not treatable through standardized means.…”