Gene therapy for canine cancer: clinical results

Abstract

Despite the important progress obtained in the treatment of some pets malignancies, new treatments need to be developed. In this review we discuss the bases and we summarize the outcomes of published gene therapy veterinary clinical trials reported by many research centers up to date. A variety of tumors such as canine soft tissue sarcomas, osteosarcoma and lymphoma were subjected to different approaches. However, spontaneous canine melanoma (a highly aggressive tumor resistant to current therapies) was the preferred target. Both viral and mainly non-viral vectors as well as cytokine producing transgenic cells were used to deliver gene products as cytokines, suicide enzymes, xenogeneic tumor antigens, anti-angiogenic molecules and pro-apoptotic regulatory factors. Among other examples, we are presenting our own successful experience with suicide plus immunogene therapy for spontaneous canine melanomas and sarcomas. In general terms, very slight or no adverse collateral effects were found during this kind of treatments and usually treated patients displayed a better course of the disease (longer survival, delayed or suppressed local or systemic relapse, recovery of the quality of life), suggesting the utility of this sort of methodology as standard adjuvant treatment. The encouraging outcomes obtained in companion animals support their ready application in veterinary clinical oncology and serve as preclinical proof of concept and safety assay for future human gene therapy trials.