Electroporation Enhances Bleomycin Efficacy in Cats with Periocular Carcinoma and Advanced Squamous Cell Carcinoma of the Head

Abstract

Background: Advanced carcinoma of the head represents a substantial health problem in cats for local control and overall survival.

Objectives: Evaluate the capability of electrochemotherapy (ECT) to improve bleomycin efficacy in cats with periocular carcinoma and advanced carcinoma of the head.

Animals: Twenty-one cats with periocular carcinoma (17 squamous cell carcinoma [SCC] and 4 anaplastic carcinoma) and 26 cats with advanced SCC of the head.

Methods: Nonrandomized prospective controlled study. Periocular carcinoma cohorts: 12 cats were treated with bleomycin (15 mg/m(2) i.v.) coupled with ECT under anesthesia; 9 cats were treated with bleomycin alone. Advanced head SCC cohorts: 14 cats were treated with bleomycin (15 mg/m(2) i.v.) coupled with ECT administered under sedation; 12 control cats were treated with bleomycin alone. ECT treatments (2-8) were performed every other week until complete remission (CR) or tumor progression occurred.

Results: Toxicities were minimal and mostly treated symptomatically. Overall response rate in the ECT treated animals was 89% (21 Complete Response [CR] and 2 Partial Response [PR]) whereas controls had response rate of 33% (4 CR and 3 PR). Median time to progression in ECT group was 30.5 months, whereas in controls it was 3.9 months (P < .0001). Median time to progression for ECT cohorts was 24.2 months for periocular cohort and 20.6 in advanced head SCC cohort, respectively.

Conclusions: Electrochemotherapy is well tolerated for advanced SCC of the head in cats; its use may be considered among loco-regional strategies for cancer therapy in sensitive body regions such as periocular region.

Keywords: Biphasic Pulses; Carcinoma; Electroporation; Feline.

Figure 1

A 12‐year‐old female spayed cat with palpebral carcinoma. Patient at presentation (A), during an electrochemotherapy treatment (B) and at the completion of treatment consisting with 6 treatments (C and D).

Figure 2

(A) Advanced lip and buccal squamous cell carcinoma in a 12‐year‐old cat at presentation. (B) The cat was treated with systemic bleomycin at a dosage of 15 mg/m² followed by permeabilizing pulses. (C) The cat at the time of the third treatment. (D) After 5 treatments, the tumor went on to resolve completely. Adverse effects were limited to scratching.

Figure 3

(A) Advanced head squamous cell carcinoma in a 13‐year‐old cat at presentation. (B) The cat was treated with systemic bleomycin at a dosage of 15 mg/m² followed by permeabilizing pulses. (C) The cat at the time of the third treatment. (D) After 5 treatments the tumor went on to resolve completely. Adverse effects were limited to scratching.

Figure 4

An 11‐year‐old male castrated cat with advanced periocular carcinoma. Patient at presentation (A), after 2 treatments of electrochemotherapy (ECT) (B), at the time of the 6th and last ECT (C) and at 1 month follow‐up (D). The patient died of pulmonary metastases 5 months after completion of ECT.

Figure 5

A 10‐year‐old female spayed cat with carcinoma at the canthus of the eye. Patient at presentation (A), and at 1 month follow‐up after only 2 treatments of electrochemotherapy (B).

Figure 6

Kaplan–Meier curve for time to progression for 26 cats treated with electrochemotherapy (blue line) and for 21 cats treated with bleomycin alone (green line) for advanced head and periocular carcinoma. The censored cats are those still alive at the time of the analysis.