Photodynamic therapy of superficial nasal planum squamous cell carcinomas in cats: 55 cases

Marginal resection and infracyanine green-mediated photodynamic therapy in the management of feline eyelid squamous cell carcinoma: Two cases

OBJECTIVE

Describe the presenting features, surgical procedure, and clinical outcomes of two cats managed with marginal resection and photodynamic therapy (PDT) for eyelid squamous cell carcinoma (SCC).

ANIMALS STUDIED

A 12-year-old female spayed domestic shorthair cat (case 1) and a 10-year-old female spayed domestic shorthair cat (case 2).

PROCEDURES

Following marginal resection of the eyelid neoplasm, hemostasis was achieved using a handheld cautery unit then 1 mL of infracyanine green was injected into the surgical wound bed. Photodynamic therapy was performed using an 810 nm diode laser in two consecutive steps: (i) six cycles at 500 mW for 30 s per cycle, using a rapid movement; then (ii) one (case 1) or two cycles (case 2) of 30 s at 2000 mW, using a slow deliberate movement to effect (charred surface).

RESULTS

Histopathology was consistent with SCC resected with incomplete margins in both cats. Follow-up duration was 416 and 161 days in case 1 and case 2, respectively. Consecutive exams and photo-documentation (in clinic or by owners) showed appropriate healing of the lower eyelid, with a smooth lid margin, and no evidence of tumor regrowth or ocular irritation. Subtle trichiasis was noted in case 1 on day 185, but not at the last follow-up.

CONCLUSIONS AND CLINICAL RELEVANCE

Marginal resection followed by PDT may be a valid alternative to complete surgical resection of periocular SCC in cats. The procedure was easy to perform, post-operative recovery was uncomplicated, and neither cat developed recurrent disease during the follow-up period.

Pilot study evaluating stereotactic body radiation therapy for feline facial squamous cell carcinomas

OBJECTIVES

The use of stereotactic body radiation therapy (SBRT) has not been assessed in advanced-stage feline solar-induced facial squamous cell carcinomas (SCCs). The objective of this study was to provide preliminary data on the use and safety profile of coarse fractions administered with an SBRT regime to manage advanced-stage feline solar-induced facial SCCs.

METHODS

This retrospective study assessed five cats diagnosed with advanced-stage solar-induced facial SCCs that received SBRT as their primary treatment or, in one cat, following failed surgical intervention. Tumour sites received three fractions totalling 26.25-27 Gy over a 3-5-day period.

RESULTS

All patients developed acute effects following SBRT including alopecia, epilation and erythema. Late effects were mild and included alopecia, variable pigmentation and leukotrichia within radiation fields. All patients were alive at the time of article submission, with overall survival times ranging from 118 to 991 days.

CONCLUSIONS AND RELEVANCE

The results suggest that coarse fractions administered with an SBRT technique is a safe and effective treatment tool for the management of advanced-stage feline solar-induced facial SCCs. These data provide preliminary evidence to support larger, prospective studies evaluating the management of feline facial SCCs with SBRT.

Nanobody-targeted photodynamic therapy for the treatment of feline oral carcinoma: a step towards translation to the veterinary clinic

Nanobody-targeted photodynamic therapy (NB-PDT) has been developed as a potent and tumor-selective treatment, using nanobodies (NBs) to deliver a photosensitizer (PS) specifically to cancer cells. Upon local light application, reactive oxygen species are formed and consequent cell death occurs. NB-PDT has preclinically shown evident success and we next aim to treat cats with oral squamous cell carcinoma (OSCC), which has very limited therapeutic options and is regarded as a natural model of human head and neck SCC. Immunohistochemistry of feline OSCC tissue confirmed that the epidermal growth factor receptor (EGFR) is a relevant target with expression in cancer cells and not in the surrounding stroma. Three feline OSCC cell lines were employed together with a well-characterized human cancer cell line (HeLa), all with similar EGFR expression, and a low EGFR-expressing human cell line (MCF7), mirroring the EGFR expression level in the surrounding mucosal stroma. NB_A was identified as a NB binding human and feline EGFR with comparable high affinity. This NB was developed into NiBh, a NB-PS conjugate with high PS payload able to effectively kill feline OSCC and HeLa cell lines, after illumination. Importantly, the specificity of NB-PDT was confirmed in co-cultures where only the feline OSCC cells were killed while surrounding MCF7 cells were unaffected. Altogether, NiBh can be used for NB-PDT to treat feline OSCC and further advance NB-PDT towards the human clinic.

A Retrospective Multicentric Study of Electrochemotherapy in the Treatment of Feline Nasal Planum Squamous Cell Carcinoma

Feline squamous cell carcinoma (SCC) is currently treated with surgery, radiation therapy and electrochemotherapy (ECT). Both the efficacy and/or safety of ECT were evaluated as a sole therapy with bleomycin to treat feline nasal planum SCC (npSCC). Sixty-one cats were enrolled. Local treatment response was evaluated as complete remission (CR), partial remission (PR) or stable disease (SD). Recurrence rate (RR), disease-free interval (DFI) and progression free survival (PFS) were calculated. A six-point scale was used for ECT toxicity. The median tumor size was 1.5 cm. CR was achieved in 65.6% of cases, PR in 31.1% and SD in 3.3%. The overall response rate was 96.7%, RR was 22.5%, median DFI was 136 days, and median PFS was 65.5 days. ECT toxicity was ≤2 in 51% of cats. Tumor recurrence/progression (p = 0.014) and local treatment response (PR: p < 0.001; SD: p < 0.001) influenced survival time. Cats with toxicity >2 showed a higher probability of tumor recurrence/progression. Tumor-related death was higher in cats with PR (p < 0.001) and recurrence/progression (p = 0.002), in ECT treatment with 1 Hz (p = 0.035) and 1200 V/cm (p = 0.011) or 1300 V/cm (p = 0.016). Tumor size influenced local treatment response (p = 0.008) and toxicity (p < 0.001). ECT is an effective treatment for feline npSCCs and should be considered as the first-line procedure for low-stage tumors.

Comparison of two different doses of bleomycin in electrochemotherapy protocols for feline cutaneous squamous cell carcinoma nonsegregated from ultraviolet light exposure

Cutaneous squamous cell carcinoma (cSCC) is one of the most common skin tumors in cats due to chronic exposure to ultraviolet light. Local treatments such as electrochemotherapy (ECT) promote disease control or even complete remission. We hypothesize that cats could benefit from treatments using bleomycin at reduced dosages. A prospective nonrandomized single-blind study evaluated the clinical parameters, site lesion, staging, disease-free interval (DFI) and survival time by comparing the standard dose of bleomycin (15,000 UI/m2) (n = 22) with a reduced dose (10,000 UI/m2) (n = 34) in cats with cSCC that underwent ECT as the sole treatment modality. No statistically significant difference in DFI or overall survival was observed between the 2 groups. A higher DFI was found in cats with a small tumor size (less than 0.33 cm3) compared with that for cats with a large tumor size (P = 0.045). Furthermore, a reduced overall survival time for cats with a higher stage in the standard group SG (T3 and T4) (P = 0.004) was observed when compared to that for cats with a lower stage (T1 and T2). In conclusion, ECT using both doses of bleomycin may achieve the same response rate in terms of the overall response, DFI, and overall survival.

Lip-to-nose flap for reconstruction of the nasal planum after curative intent excision of squamous cell carcinoma in cats: Description of technique and outcome in seven cases

OBJECTIVE

To describe the surgical technique for nasal planum reconstruction with a lip-to-nose flap after curative intent surgical excision of squamous cell carcinoma (SCC) in cats and to report the surgical outcomes.

STUDY DESIGN

Short case series.

ANIMALS

Seven cats with SCC of the lateral (n = 6) or dorsal (n = 1) aspect of the nasal planum.

METHODS

After tumor excision, a mucocutaneous lip-to-nose flap was harvested from the upper lip and transposed to reconstruct the nasal planum. Variables recorded included surgical time, surgical complications, healing complications, flap success rate, and cosmetic and long-term functional outcomes.

RESULTS

Median surgical time was 67.5 minutes (range 49-80), and no intraoperative complications occurred. Postoperatively, six cats developed self-limiting edema of the muzzle, and one cat had nasal discharge for 2 days. No major complications occurred during the healing process, and all cats went on to achieve successful healing of their flap. A small area of partial-thickness necrosis developed at the cranial edge of the flap in three cats and healed spontaneously in all cases within a few days. According to owner satisfaction and periodic clinical assessment, cosmetic and long-term functional of outcomes were considered good in all cats.

CONCLUSION

The lip-to-nose flap allowed for aesthetic and functional reconstruction of the nasal planum after curative intent surgical excision of feline SCC.

CLINICAL SIGNIFICANCE

The lip-to-nose flap is an option for a single-stage reconstruction of the nasal planum following partial nasal planectomy in cats.

Efficacy of 5-Aminolevulinic Acid in Photodynamic Detection and Photodynamic Therapy in Veterinary Medicine

5-Aminolevulinic acid (5-ALA), a commonly used photosensitizer in photodynamic detection (PDD) and therapy (PDT), is converted in situ to the established photosensitizer protoporphyrin IX (PpIX) via the heme biosynthetic pathway. To extend 5-ALA-PDT application, we evaluated the PpIX fluorescence induced by exogenous 5-ALA in various veterinary tumors and treated canine and feline tumors. 5-ALA-PDD sensitivity and specificity in the whole sample group for dogs and cats combined were 89.5 and 50%, respectively. Notably, some small tumors disappeared upon 5-ALA-PDT. Although single PDT application was not curative, repeated PDT+/−chemotherapy achieved long-term tumor control. We analyzed the relationship between intracellular PpIX concentration and 5-ALA-PDT in vitro cytotoxicity using various primary tumor cells and determined the correlation between intracellular PpIX concentration and 5-ALA transporter and metabolic enzyme mRNA expression levels. 5-ALA-PDT cytotoxicity in vitro correlated with intracellular PpIX concentration in carcinomas. Ferrochelatase mRNA expression levels strongly negatively correlated with PpIX accumulation, representing the first report of a correlation between mRNA expression related to PpIX accumulation and PpIX concentration in canine tumor cells. Our findings suggested that the results of 5-ALA-PDD might be predictive for 5-ALA-PDT therapeutic effects for carcinomas, with 5-ALA-PDT plus chemotherapy potentially increasing the probability of tumor control in veterinary medicine.

Retrospective clinical study on outcome in cats with nasal planum squamous cell carcinoma treated with an accelerated radiation protocol

BACKGROUND

Cutaneous squamous cell carcinoma of the nasal planum in cats is a common indication for antitumor treatment such as external beam radiation therapy. Curative-intent radiation therapy has been described as a valuable treatment option, resulting in long and stable tumor control in these patients. The aim of the current study was to evaluate outcome and toxicity, as well as possible prognostic factors using an accelerated hypofractionated radiation therapy protocol. Cats with squamous cell carcinoma of the nasal planum treated with an accelerated radiation protocol (10 × 4.8 Gy, over one week) were retrospectively evaluated. Tumor- and treatment-associated variables were evaluated in respect to local control and survival.

RESULTS

Forty-four cats met the inclusion criteria for this study. All cats showed complete response to therapy. Median disease-free interval (DFI) for all cases was 916 days (95% CI: 456-1377). One- and two-year DFIs were 71% (95% CI: 56-86%) and 60% (95% CI: 43-77%). Of the tested variables, only tumor volume showed a tendency to influence DFI, with larger tumors having a 5.4 times greater risk of recurrence than the smaller ones (HR 1.33 (95% CI: 0.99-1.79), p = 0.054). Median overall survival (OS) was 902 days (95% CI: 862-942). One- and 2-year OSs were 79.3% (95% CI: 67.3-91.3) and 58.4% (95% CI: 42.8-74). Of the tested variables, again, only tumor volume influenced OS with larger tumors having a 6.3 times greater risk of dying than the smaller ones (HR 1.36 (95% CI: 1.07-1.73), p = 0.010). The acute and late toxicity profile was low and hence clinically acceptable.

CONCLUSIONS

Curative-intent radiation therapy with an accelerated fractionation schedule can be considered a safe, cosmetically superior treatment option for cutaneous squamous cell carcinomas of the nasal planum in cats, resulting in long and stable tumor control.

Glycolysis inhibition improves photodynamic therapy response rates for equine sarcoids

Photodynamic therapy (PDT) holds great promise in treating veterinary and human dermatological neoplasms, including equine sarcoids, but is currently hindered by the amount of photosensitiser and light that can be delivered to lesions thicker than around 2 mm, and by the intrinsic antioxidant defences of tumour cells. We have developed a new PDT technique that combines an efficient transdermal penetration enhancer solution, for topical delivery of 5-aminolevulinic acid (ALA) photosensitiser, with acute topical post-PDT application of the glycolysis inhibitor lonidamine. We show that the new PDT combination treatment selectively kills sarcoid cells in vitro, with repeated rounds of treatment increasing sarcoid sensitisation to PDT. In vivo, ALA PDT followed by 600 μM lonidamine substantially improves treatment outcomes for occult, verrucous, nodular and fibroblastic sarcoids after 1 month (93% treatment response in 27 sarcoids), compared with PDT using only ALA (14% treatment response in 7 sarcoids).

Avian Oncology: Diseases, Diagnostics, and Therapeutics

Companion birds are increasingly living longer due to improved husbandry, nutrition, and veterinary care. As a consequence, a growing number of geriatric disease conditions are diagnosed and managed by veterinarians. Awareness of bird owners of diagnostic and treatment options for neoplastic diseases in humans and domestic animals has led to increasing demand to provide advanced diagnostic and treatment modalities for companion birds diagnosed with neoplasia. Treatment remains challenging in many companion birds due to the lack of information regarding prognosis and efficacy of antineoplastic treatments in these species. There is no established standard of care for most tumors in companion birds.

The effect of photodynamic therapy on cisterna chyli patency in rats

OBJECTIVE

To radiographically and histologically evaluate the effects of photodynamic therapy on the cisterna chyli in rats.

STUDY DESIGN

Experimental study.

ANIMALS

Adult male Sprague-Dawley rats (n = 60).

METHODS

Cecal lymph nodes were injected with the photodynamic compound verteporfin. A 690 nm, 500 mW diode laser was then directed at the area of the cisterna chyli for either 0, 1.5, or 3 minutes. Cisterna chyli patency was evaluated using lymphography, and histologic changes were evaluated on postoperative Days 1, 3, 5, 7, and 14.

RESULTS

Histologically, minimal to marked injury to the cisternal and/or pericisternal tissues was present in all treated rats at all time periods. Radiographically, 8/20 cisternae were occluded in the 1.5-minute treatment group (including 1/4 on Day 1, 2/4 on Day 3, 3/4 on Day 5, 0/4 on Day 7, and 2/4 on Day 14), and 9/20 cisternae were occluded in the 3-minute treatment group (including 0/4 on Day 1, 1/4 on Day 3, 3/4 on Day 5, 3/4 on Day 7, and 2/4 on Day 14). There was minimal to no histologic evidence of tissue injury in control rats. All control cisternae were radiographically open.

CONCLUSIONS

Further investigations into the timing of laser application and light dose, or alternative photodynamic agents are required to limit injury to adjacent tissues and to improve the effectiveness of cisternal photoablation.

Cats with cancer: where to start

PRACTICAL RELEVANCE

Many cats develop cancer and may or may not present with an obvious mass lesion. As our feline patients are living longer and their owners are increasingly seeking veterinary care, the apparent incidence and prevalence of cancer is increasing.

CLINICAL CHALLENGES

Neoplasia is a differential for many clinical presentations in cats. Often tumours are relatively advanced at the point of presentation, and this can make management difficult. In addition, many cats find clinic visits stressful and this can influence owners' decisions about treatment.

AUDIENCE

This review provides an overview of the approach to the feline cancer patient, and is aimed at all veterinary practitioners that see cats. It is intended as a starting point for more detailed discussions in accompanying articles in this special issue on feline oncology.

EVIDENCE BASE

There is limited data on most feline tumours compared with tumours in canine or human patients, so a robust evidence base is often lacking.

Electrochemotherapy with intravenous bleomycin injection: an observational study in superficial squamous cell carcinoma in cats

The aim of this study was to evaluate the efficacy and safety of electrochemotherapy (ECT) with bleomycin for treatment of squamous cell carcinoma (SCC) in cats. Between March 2008 and October 2011, 11 cats with 17 superficial SCC nodules in different clinical stages (ranging from Tis to T4), located on nasal planum (6/11), pinnae (3/11) and both locations (2/11), were included in a prospective non-randomised study. Sixteen of 17 SCC nodules were treated with ECT (15/16 with single session and in one case with two sessions); one nodule was surgically removed. Altogether, complete response (CR) was achieved for 81.8% (9/11) cats and 87.5% (14/16) nodules, lasting from 2 months up to longer than 3 years. Only 2/9 cats in which CR was initially observed, had recurrence 2 and 8 months after the ECT procedure. In the remaining two cats with highly infiltrative spread into adjacent tissues, progression of the disease was observed, despite ECT, and both were euthanased 4 and 5 months after the procedure. ECT in cats was well tolerated and no evident local or systemic side effects were observed. The results of this study suggest that ECT is a highly effective and safe method of local tumour control of feline cutaneous SCCs. It should be considered as an alternative treatment option, especially when other treatment approaches are not acceptable by the owners, owing to their invasiveness, mutilation or high cost.

Veterinary photodynamic therapy: a review

Whereas in human medicine photodynamic therapy represents a well-known and recognized treatment option for diverse indications, it is still little known and unfortunately not yet established treatment option for pets. Various photosensitizers and light sources have been used and clinical results have been published. The main indication is a frequently occurring skin tumor in cats: in situ carcinoma/squamous cell carcinoma, mainly found in not or only slightly pigmented areas of the head. For early stages of this tumor, promising results have been published, partly using new, selective drugs to decrease light sensitivity after systemic administration and to increase response rates. Other possible indications are urinary tract neoplasia of dogs and equine sarcoids, the latter representing very common tumors in horses where no effective treatment is known so far. This review article summarizes the role of photodynamic therapy in veterinary medicine.

Cutaneous Squamous Cell Carcinoma in the Cat

Practical relevance:

Squamous cell carcinoma (SCC) is a tumour that commonly involves the skin or oral cavity and is, therefore, an important differential diagnosis for any cutaneous lesion(s), especially any non-healing scabbing lesions on the eyelids, nasal planum or ears of light-coloured cats.

Clinical challenges:

Superficial lesions of the nasal planum, discrete small eyelid lesions and lesions on the tips of pinnae are relatively easily treated, but higher stage lesions are more challenging to manage and may compromise the cosmetic appearance of the cat.

Audience:

This review article is aimed at all veterinary practitioners that see cats.

Evidence base:

The review summarises the peer-reviewed literature relating to our understanding of feline cutaneous SCC. Unfortunately, the literature is limited and in need of updating in areas.

Curettage and diathermy: a treatment for feline nasal planum actinic dysplasia and superficial squamous cell carcinoma

OBJECTIVE

To evaluate curettage and diathermy as a treatment for actinic dysplasia and superficial squamous cell carcinoma of the feline nasal planum.

METHODS

Thirty-four cats clinically assessed to have actinic dysplasia and superficial squamous cell carcinoma involving less than 50% of the nasal planum were treated with a three-cycle curettage and diathermy procedure. Degree of dysplasia, response to treatment, adverse effects, owner perceptions, time to recurrence and proportion disease free at 1 year were evaluated.

RESULTS

Lesions ranged from actinic keratoses to invasive squamous cell carcinoma. A complete response to treatment was obtained in all cats. The median follow-up time was 18 · 2 (IQR: 12 · 0-22 · 8) months. Two cats had a clinical recurrence of lesions at 161 and 192 days after treatment. The probability of remaining disease free after 12 months was 0 · 94 (95% CI: 0 · 85-1 · 0). Median time to recurrence was not reached. The procedure was well tolerated with a good cosmetic outcome and no significant post-operative complications.

CLINICAL SIGNIFICANCE

This study suggests that curettage and diathermy is an effective treatment for feline actinic dysplasia and for superficial squamous cell carcinoma involving less than 50% of the nasal planum. Curettage and diathermy is an easily mastered technique, requiring minimal equipment.

Cellular localization of Visudyne as a function of time after local injection in an in vivo model of squamous cell carcinoma: an investigation into tumor cell death

OBJECTIVE

To evaluate the effects of time on cellular localization of Visudyne after local injection.

ANIMALS

Twenty athymic nude mice.

PROCEDURES

A squamous cell carcinoma (SCC) cell line (A-431) was injected into right and left dorsolumbar subcutaneous tissue of each mouse, representing treatment (T) and control (C) tumors. In experiment 1 (Exp 1; n = 10) and 2 (Exp 2; n = 10), the T tumors received a local injection of Visudyne (0.1 mg/cm(3)), and C tumors received an equal dose of 5% dextrose in water (D5W). Mice were randomly subdivided into two groups (A and B; n = 5 per group). Mice in Exp 1A and B were sacrificed 1 and 30 min after local injection, respectively. Experiment 1A and B tumors were evaluated by fluorescence microscopy to determine drug localization. Experiment 2A and B tumors were exposed to LED illumination 1 and 30 min after injection, respectively, and evaluated by transmission electron microscopy (TEM) to determine ultrastructural tumor cell damage.

RESULTS

Fluorescence was detected within the cytoplasm of T tumors in both Exp 1A and B. Significance was detected in fluorescence intensity between T1 min vs. T30 min (P = 0.03) and between T1 min and C1 min tumors (P = 0.01), respectively. Tumors in Exp 2A and B demonstrated evidence of apoptotic cell death.

CONCLUSIONS

Fluorescence microscopy demonstrated higher Visudyne concentration within SCC cytoplasm of 1 min compared with 30-min tumors. Transmission electron microscopy results revealed that tumors treated by photodynamic therapy (PDT) within 30 min of local injection undergo cellular apoptosis.