Photodynamic Therapy of Feline Cutaneous Squamous Cell Carcinoma Using a Newly Developed Liposomal Photosensitizer: Preliminary Results Concerning Drug Safety and Efficacy

Abstract

Background: Squamous cell carcinomas are common skin tumors in cats. We investigated photodynamic therapy (PDT) using a new liposomal photosensitizer as a minimally invasive, effective treatment that can be easily performed while achieving good cosmetic results.Aim: The goal of this study was to assess and describe possible toxicities using a liposomal formulation of the photosensitizer meta-(Tetrahydroxyphenyl)Chlorin (m-THPC) and investigate if favorable pharmacokinetics translate into favorable tumor response and control.Animals: Eighteen client-owned cats with 20 spontaneous cutaneous squamous cell carcinomas were included in the study. Methods: PDT was performed using a new, liposomal formulation of the photosensitizer. Toxicity, tumor response, and tumor control were evaluated retrospectively.Results: No general adverse effects were observed in cats treated with the new liposomal formulation. Mild local toxicity such as erythema and edema were seen in 15% of the patients. All cats responded to therapy, with a complete response rate of 100%. The overall 1-year control rate was 75%. The tumor recurrence rate was 20% with a median time to recurrence of 172.25 (687.1) days.Conclusions and Clinical Importance: A new liposomal photosensitizer was successfully used for squamous cell carcinoma in cats and was well tolerated. There were no systemic adverse effects observed with the liposomal formulation. The favorable pharmacokinetics of the liposomal drug resulted in a favorable tumor response.

Photodynamic therapy with conventional and PEGylated liposomal formulations of mTHPC (temoporfin): comparison of treatment efficacy and distribution characteristics in vivo

“…[9][10][11] It appears from our study that irrespective of the formulation, and at identical mTHPC concentrations in the tumor, the PDT efficacy is identical ( Figure 4 and Table 3). An exception here is at 15 hours DLI, where Fospeg ® appears to be much more effective compared to Foslip ® .…”

“…[8][9][10][11] However, no detailed in vivo comparison of these liposomal formulations in the same model has been reported to date. The aspects of comparison of the two liposomal mTHPC forms were the tumor and plasma fluorescence kinetics in the window-chamber model in rats 12 and photothrombic activity in the tumor-free chick chorioallantoic membrane.…”

Utilização de eletroquimioterapia para carcinoma de células escamosas tegumentar em felino

“…Tais procedimentos demonstram expressivas disparidades relativas a eficácia, duração do tratamento, período de recuperação do paciente, segurança e onerosidade (Klein 2003, Ferreira et al 2006, Lucas & Larsson 2006, Buchholz et al 2007, Hammond et al 2007, Thomson 2007, Bexfield et al 2008. Assim, estudos suplementares estão sendo amplamente desenvolvidos na busca por alternativas terapêuticas mais efetivas e seguras (Čemažar et al 2001, Gothelf et al 2003, Aminkov & Manov 2004, Chen et al 2006, Withrow & Vail 2007, Serša et al 2011, Meschini et al 2012, Gibot et al 2013.…”

“…A bibliografia oncológica veterinária disponibiliza inú-meros de protocolos para o tratamento do carcinoma de células escamosas felino, incluindo excisão cirúrgica, criocirurgia, terapia fotodinâmica, quimio e/ou radioterapia (Klein 2003, Ferreira et al 2006, Lucas & Larsson 2006, Buchholz et al 2007, Hammond et al 2007, Thomson 2007, Bexfield et al 2008. Entretanto, tais protocolos exibem limitações principalmente representadas por adversidades, resposta terapêutica e custo (Klein 2003, Ferreira et al 2006, Lucas & Larsson 2006, Buchholz et al 2007, Hammond et al 2007, Thomson 2007, Bexfield et al 2008.…”

“…Entretanto, tais protocolos exibem limitações principalmente representadas por adversidades, resposta terapêutica e custo (Klein 2003, Ferreira et al 2006, Lucas & Larsson 2006, Buchholz et al 2007, Hammond et al 2007, Thomson 2007, Bexfield et al 2008.…”