Adjuvant immunotherapy of feline injection-site sarcomas with the recombinant canarypox virus expressing feline interleukine-2 evaluated in a controlled monocentric clinical trial when used in association with surgery and brachytherapy

Feline Injection-Site Sarcoma and Other Adverse Reactions to Vaccination in Cats

Vaccine-associated adverse events (VAAEs), including feline injection-site sarcomas (FISSs), occur only rarely but can be severe. Understanding potential VAAEs is an important part of informed owner consent for vaccination. In this review, the European Advisory Board on Cat Diseases (ABCD), a scientifically independent board of feline medicine experts, presents the current knowledge on VAAEs in cats, summarizing the literature and filling the gaps where scientific studies are missing with expert opinion to assist veterinarians in adopting the best vaccination practice. VAAEs are caused by an aberrant innate or adaptive immune reaction, excessive local reactions at the inoculation site, an error in administration, or failure in the manufacturing process. FISS, the most severe VAAE, can develop after vaccinations or injection of other substances. Although the most widely accepted hypothesis is that chronic inflammation triggers malignant transformation, the pathogenesis of FISS is not yet fully understood. No injectable vaccine is risk-free, and therefore, vaccination should be performed as often as necessary, but as infrequently as possible. Vaccines should be brought to room temperature prior to administration and injected at sites in which FISS surgery would likely be curative; the interscapular region should be avoided. Post-vaccinal monitoring is essential.

Electrochemotherapy Plus IL-2+IL-12 Gene Electrotransfer in Spontaneous Inoperable Stage III-IV Canine Oral Malignant Melanoma

Electrochemotherapy (ECT) is a standard of care in veterinary and human oncology. The treatment induces a well-characterized local immune response which is not able to induce a systemic response. In this retrospective cohort study, we evaluated the addition of gene electrotransfer (GET) of canine IL-2 peritumorally and IL-12 intramuscularly to enhance the immune response. Thirty canine patients with inoperable oral malignant melanoma were included. Ten patients received ECT+GET as the treatment group, while twenty patients received ECT as the control group. Intravenous bleomycin for the ECT was used in both groups. All patients had compromised lymph nodes which were surgically removed. Plasma levels of interleukins, local response rate, overall survival, and progression-free survival were evaluated. The results show that IL-2 and IL-12 expression peaked around days 7-14 after transfection. Both groups showed similar local response rates and overall survival times. However, progression-free survival resulted significantly better in the ECT+GET group, which is a better indicator than overall survival, as it is not influenced by the criterion used for performing euthanasia. We can conclude that the combination of ECT+GET using IL-2 and IL-12 improves treatment outcomes by slowing down tumoral progression in stage III-IV inoperable canine oral malignant melanoma.

ALVAC-fIL2, a feline interleukin-2 immunomodulator, as a treatment for sarcoids in horses: A pilot study

Background

Sarcoid tumors are common in horses and may negatively impact the performance and value of the horse. No known treatment is reliably successful.

Hypotheses/Objectives

To determine tolerability, overall response rate, time to response, and progression‐free survival of horses with biopsy‐confirmed or suspected sarcoids treated with ALVAC‐fIL2.

Animals

Client‐owned horses with measurable, presumed‐ or biopsy‐confirmed sarcoid tumors.

Methods

Prospective pilot study. One milliliter of ALVAC‐fIL2 was injected into 4 to 5 areas of the sarcoid(s) in each horse (week 0); this treatment was repeated in weeks 1, 3, and 7. Sarcoids were measured at each visit, and response to treatment was determined according to the Response Evaluation Criteria in Solid Tumors for dogs (v1.0). After the final treatment, horses were reassessed and sarcoids remeasured every 3 months until tumor progression or for a minimum of 1 year if progression was not documented.

Results

Fourteen horses were included. Tumor size decreased in 86% of the horses, and the median time to first response was 89 days (range, 34‐406 days). Median time to best response was 211 days (range, 56‐406 days), but 3 of the sarcoids still were decreasing in size at the time of final evaluation. The median progression‐free interval was not reached. Adverse events were minimal and included transient focal inflammation in 2 horses.

Conclusions and Clinical Importance

Intratumoral injection of ALVAC‐fIL2 has promise as a well‐tolerated and effective, tissue‐sparing treatment for horses with sarcoid tumors.

Treatment of equine sarcoids using recombinant poxviruses expressing feline interleukin-2

BACKGROUND

Interleukin (IL)-2 stimulates antitumour immunity and is successfully used for the treatment of different neoplasias.

HYPOTHESIS/OBJECTIVES

Canarypox virus locally expressing feline IL-2 is safe and can be used to treat equine sarcoids.

ANIMALS

Twenty horses of different breeds with a median age of eight years (interquartile range 6.0-13.3 years) and a total number of 59 sarcoids were included in the study.

METHODS

In this prospective clinical trial, sarcoids were injected twice seven days apart, with a recombinant canarypox virus expressing feline IL-2. Complete blood counts (CBC) and fibrinogen levels were measured before treatment and on days 1, 2, 7 and 8.

RESULTS

Complete regression was achieved in eight horses (40%) and partial regression in two horses (10%). No change in sarcoid size was observed in two horses (10%) and the disease progressed in five horses (25%). Sarcoids of three horses (15%) showed initial response followed by tumour growth. There were no significant changes in CBC and fibrinogen levels after either injection. One horse developed a mild fever the day after each injection, which subsided without treatment the following day.

CONCLUSIONS

Treatment of equine sarcoids with recombinant canarypox virus expressing feline IL-2 seems to be a safe therapy option. Although the expression of IL-2 after vector injection and its biological activity in horses were not proven in this study, the treatment resulted in regression and partial regression in 50% of the cases. Further studies are necessary to verify these findings and to establish a treatment protocol.

Treatment of feline injection-site sarcoma with surgery and iridium-192 brachytherapy: retrospective evaluation of 22 cats

OBJECTIVES

The aim of this retrospective descriptive study was to determine the effectiveness of using iridium implants in addition to surgery in cats with feline injection-site sarcomas (FISSs) in terms of time to progression and disease-specific survival and to identify prognostic factors for patient outcome.

METHODS

Medical records of cats presented at our institution with FISS were reviewed. Inclusion criteria included histologic diagnosis of a tumor type associated with post-injection neoplastic development, tumor located at a site associated with vaccination, no other therapies prior to the administration of brachytherapy with the exception of surgery and adequate follow-up data.

RESULTS

Twenty-two cats with FISS were treated with surgery and brachytherapy delivered by postoperative iridium-192 interstitial implants. Radiation doses ranged from 4000 to 6000 cGy (median dose 5079.55 cGy), with most doses delivered over 7 days. The median number of surgeries prior to brachytherapy was one (range 1-4). The complications associated with postoperative brachytherapy were typically mild, although four cats developed more severe complications. The median time to progression for all cats was 619 days and disease-specific survival time for all cats was 1242 days. The 1 and 2 year tumor-free rates in these cats were 63.6% and 40.9%, respectively. The local failure rate was 54.5% and the distant failure rate was 13.6% due to lung metastasis. There was a significant difference in time to progression of cats that had a single surgery performed prior to brachytherapy and those that had multiple surgeries (undefined vs 310 days; P = 0.01). There were no other statistically significant identified prognostic factors.

CONCLUSIONS AND RELEVANCE

These data suggest that the addition of brachytherapy postoperatively in cats with FISS was well tolerated and is comparable to other forms of adjuvant therapy.

Emerging therapeutic approaches for canine sarcomas: Pushing the boundaries beyond the conventional

Sarcomas represent a group of genomically chaotic, highly heterogenous tumours of mesenchymal origin with variable mutational load. Conventional therapy with surgery and radiation therapy is effective for managing small, low-grade sarcomas and remains the standard therapeutic approach. For advanced, high-grade, recurrent, or metastatic sarcomas, systemic chemotherapy provides minimal benefit, therefore, there is a drive to develop novel approaches. The discovery of "Coley's toxins" in the 19th century, and their use to stimulate the immune system supported the application of unconventional therapies for the treatment of sarcomas. While promising, this initial work was abandoned and treatment paradigm and disease course of sarcomas was largely unchanged for several decades. Exciting new therapies are currently changing treatment algorithms for advanced carcinomas and melanomas, and similar approaches are being applied to advance the field of sarcoma research. Recent discoveries in subtype-specific cancer biology and the identification of distinct molecular targets have led to the development of promising targeted strategies with remarkable potential to change the landscape of sarcoma therapy in dogs. The purpose of this review article is to describe the current standard of care and limitations as well as emerging approaches for sarcoma therapy that span many of the most active paradigms in oncologic research, including immunotherapies, checkpoint inhibitors, and drugs capable of cellular metabolic reprogramming.

Role of nuclear factor-kappa B in feline injection site sarcoma

Background

Chronic inflammation has been implicated in sarcomagenesis. Among various factors, activation of nuclear factor-kappa B (NF-κB) signaling pathway has been documented being able to target genes associated with tumor progression and up-regulate the expression of tumor-promoting cytokines and survival genes in several human solid tumors. Feline injection sites sarcomas (FISS) are malignant entities derived from the mesenchymal origin. The disease has been considered to be associated with vaccine adjuvant, aluminum, which serves as a stimulus continuously inducing overzealous inflammatory and immunologic reactions. To understand the contribution of NF-κB in FISS, detection of activated NF-κB in paraffin-embedded specimens, in vitro establishment of primary cells derived from FISS, and evaluation of the effects of the NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), on primary tumor cells were conducted.

Results

In this study, nuclear expression of NF-κB p65 was detected in 83.3% of FISS cases and not correlated with tumor grading, sex, and age. Primary cells derived from FISS in three cats exhibiting same immunohistochemical characteristics as their original tumor were successfully established. The NF-κB inhibitor, DHMEQ, was able to prevent nuclear translocation of NF-κB p65, inhibit cell proliferation, migration, and colonization in dosage-dependent manners, and induce cell apoptosis in these primary FISS cells.

Conclusions

High expression rate of nuclear NF-κB p65 in FISS cases and dose-dependent inhibitory effects on the growth of FISS primary cells treated with NF-κB inhibitor suggested that NF-κB might be a potential molecular therapeutic target for FISS.

Elucidating the transcriptional program of feline injection-site sarcoma using a cross-species mRNA-sequencing approach

BACKGROUND

Feline injection-site sarcoma (FISS), an aggressive iatrogenic subcutaneous malignancy, is challenging to manage clinically and little is known about the molecular basis of its pathogenesis. Tumor transcriptome profiling has proved valuable for gaining insights into the molecular basis of cancers and for identifying new therapeutic targets. Here, we report the first study of the FISS transcriptome and the first cross-species comparison of the FISS transcriptome with those of anatomically similar soft-tissue sarcomas in dogs and humans.

METHODS

Using high-throughput short-read paired-end sequencing, we comparatively profiled FISS tumors vs. normal tissue samples as well as cultured FISS-derived cell lines vs. skin-derived fibroblasts. We analyzed the mRNA-seq data to compare cancer/normal gene expression level, identify biological processes and molecular pathways that are associated with the pathogenesis of FISS, and identify multimegabase genomic regions of potential somatic copy number alteration (SCNA) in FISS. We additionally conducted cross-species analyses to compare the transcriptome of FISS to those of soft-tissue sarcomas in dogs and humans, at the level of cancer/normal gene expression ratios.

RESULTS

We found: (1) substantial differential expression biases in feline orthologs of human oncogenes and tumor suppressor genes suggesting conserved functions in FISS; (2) a genomic region with recurrent SCNA in human sarcomas that is syntenic to a feline genomic region of probable SCNA in FISS; and (3) significant overlap of the pattern of transcriptional alterations in FISS with the patterns of transcriptional alterations in soft-tissue sarcomas in humans and in dogs. We demonstrated that a protein, BarH-like homeobox 1 (BARX1), has increased expression in FISS cells at the protein level. We identified 11 drugs and four target proteins as potential new therapies for FISS, and validated that one of them (GSK-1059615) inhibits growth of FISS-derived cells in vitro.

CONCLUSIONS

(1) Window-based analysis of mRNA-seq data can uncover SCNAs. (2) The transcriptome of FISS-derived cells is highly consistent with that of FISS tumors. (3) FISS is highly similar to soft-tissue sarcomas in dogs and humans, at the level of gene expression. This work underscores the potential utility of comparative oncology in improving understanding and treatment of FISS.

Curative-intent radical en bloc resection using a minimum of a 3 cm margin in feline injection-site sarcomas: a retrospective analysis of 131 cases

Objectives Owing to its highly infiltrative growth, feline injection-site sarcoma (FISS) carries a significant risk of local tumour recurrence. Parameters of possible prognostic significance (eg, tumour size and location, resection of de novo vs recurrent tumours, and achievement of tumour-free surgical margins) were examined with regard to their influence on recurrence rate (RR), disease-free interval (DFI) and survival time (ST). Methods This was a retrospective analysis of cats with FISSs located on the chest or abdominal wall or the interscapular region treated in a single institution using a standardised radical resection technique with 3 cm lateral margins and full-thickness body wall resection (tumours over chest/abdominal wall) or a minimum of two fascial planes (interscapular tumours). Results Median postoperative DFI and ST of 131 cats with FISSs was 21 and 24 months, respectively. Patients operated on for recurrent tumours were significantly more likely to die from tumour-related reasons compared with patients with de novo tumours ( P <0.001). RR and DFI in the different tumour locations were comparable ( P = 0.544 and P = 0.17, respectively). Local tumour recurrence occurred in 38.1% of the cats. Cats operated on for tumour recurrences had a significantly higher chance of another recurrence (RR 55.5% vs 33.3%; P = 0.005). Completeness of excision was determined by taking tumour bed biopsies. Tumour bed biopsies that did not contain tumour cells were associated with a significantly lower RR compared with those with tumour cells (30.5% vs 76.2%). Conclusions and relevance Depending on prognostic factors such as surgery for primary vs recurrent tumour, tumour-free resection margins and tumour location, the RR in FISS ranges from 33-55%, despite curative intent radical surgery. This study may help in identifying patients at risk for recurrence.

Current knowledge on feline injection-site sarcoma treatment

Feline injection-site sarcomas (FISS) are malignant skin tumours of mesenchymal origin, the treatment of which is a challenge for veterinary surgeons. The role of surgery, radiotherapy and chemotherapy in FISS treatment has been studied, and a correlation between “clean” surgical margins and disease-free survival has been shown. In addition, clean surgical margins are one of the most important factors for achieving a low recurrence rate. The most effective method of FISS treatment includes combining radical surgery with pre- or postoperative radiotherapy. Chemotherapy may be used as a palliative method of treatment or may be considered an adjunctive therapy for surgery and radiotherapy. In cats with FISS without metastasis, the use of immunostimulant treatment with Oncept IL-2, intended as a complementary immunotherapy in association with surgery and brachytherapy, may also be considered to reduce the risk of relapse and increase the time to relapse. Additionally, this review focuses on recent advances in FISS treatment, including the use of novel compounds, such as doxorubicin conjugated to glutathione-stabilized gold nanoparticles, liposomal doxorubicin or tyrosine kinase inhibitors.

Recent clinical trials of cancer immunogene therapy in companion animals

This mini-review presents the results of veterinary clinical trials on immunogene therapy published from 2014 to 2016. A variety of tumors, among them melanoma (canine and equine), mastocytoma (canine), mammary adenocarcinoma (canine) and fibrosarcoma (feline) were treated by using diverse strategies. Non-viral vectors were usually employed to transfer genes of cytokines, suicide enzymes and/or tumor associated antigens. In general terms, minor or no adverse collateral effects were related to these procedures, and treated patients frequently improved their conditions (better quality of life, delayed or suppressed recurrence or metastatic spread, increased survival). Some of these new methodologies have a promising future if applied as adjuvant treatments of standard approaches. The auspicious results, derived from immunogene therapy studies carried out in companion animals, warrant their imperative usage in veterinary clinical oncology. Besides, they provide a strong preclinical basis (safety assays and proofs of concept) for analogous human clinical trials.

Feline injection-site sarcoma: ABCD guidelines on prevention and management

OVERVIEW

In cats, the most serious of adverse effects following vaccination is the occurrence of invasive sarcomas (mostly fibrosarcomas): so-called 'feline injection-site sarcomas' (FISSs). These develop at sites of previous vaccination or injection. They have characteristics that are distinct from those of fibrosarcomas in other areas and behave more aggressively. The rate of metastasis ranges from 10-28%.

PATHOGENESIS

The pathogenesis of these sarcomas is not yet definitively explained. However, chronic inflammatory reactions are considered the trigger for subsequent malignant transformation. Injections of long-acting drugs (such as glucocorticoids, and others) have been associated with sarcoma formation. Adjuvanted vaccines induce intense local inflammation and seem therefore to be particularly linked to the development of FISS. The risk is lower for modified-live and recombinant vaccines, but no vaccine is risk-free.

TREATMENT AND PREVENTION

Aggressive, radical excision is required to avoid tumour recurrence. The prognosis improves if additional radiotherapy and/or immunotherapy (such as recombinant feline IL-2) are used. For prevention, administration of any irritating substance should be avoided. Vaccination should be performed as often as necessary, but as infrequently as possible. Non-adjuvanted, modified-live or recombinant vaccines should be selected in preference to adjuvanted vaccines. Injections should be given at sites at which surgery would likely lead to a complete cure; the interscapular region should generally be avoided. Post-vaccination monitoring should be performed.