Electrochemotherapy for the treatment of primary basal cell carcinoma; A randomised control trial comparing electrochemotherapy and surgery with five year follow up.

Basal cell carcinoma (BCC) are the commonest cutaneous malignancy and incidence continues to increase. There is a need to expand the therapeutic toolbox to increase options for patients that are unsuitable for or unwilling to undergo the current therapies. Electrochemotherapy (ECT) is a technique where cells are temporarily permeabilized after exposure to a brief pulsed electrical field and combined with low dose chemotherapeutics to ablate malignancies. It is a simple technique causing minimal damage to the surrounding healthy tissue and has the potential to avoid the need for complex reconstruction. ECT is an established treatment for skin metastases but its role as a primary treatment modality is not demonstrated. A prospective randomised control trial evaluating ECT against the gold standard of treatment, Surgery, was performed for patients with primary BCC and patients followed for 5 years. All lesions treated with ECT (n = 69) responded although 8/69 (12%) needed a second treatment to ensure a complete response. All surgical lesions (n = 48) showed histological evidence of complete excision with 2/48 (4%) undergoing a second excision. At 5 years, in the surgical arm there was no evidence of recurrence in 39/40 (97.5%) lesions with 1/40 (2.5%) confirmed recurrence. In the ECT arm there was no evidence of recurrence in 42/48 lesions (87.5%). There was 5 confirmed recurrences. These groups show statistical equivalence in this non inferiority study design (p = 0.33). ECT is an effective and durable treatment option for primary BCC and should be considered as part of the armamentarium of options available.

The treatment of canine mast cell tumours with electrochemotherapy with or without surgical excision.

To describe the results of electrochemotherapy (ECT) in dogs with mast cell tumours (MCTs) either as first line therapy or as an adjuvant to surgery. The treatment combines administration of low dose chemotherapeutic drugs with the application of microsecond electric pulses, which cause the temporary permeabilization and increased porosity of the tumour cell membranes. The design of this study is a retrospective case series. A total of 51 dogs with MCTs were included and classified according to ECT procedure into 4 groups (ECT only, 15 cases, intra-surgery ECT, 11, ECT Adjuvant to surgery, 14, Surgery followed by ECT, 11). The four groups (staged with location, size and grade) were evaluated to assess complete or partial remission, disease free interval, overall survival time and local toxicity. In this case series, Boxers, mixed breed and Labrador Retrievers, male dogs, between 4 and 9 years old were more represented. MCTs were predominantly grade 2 (Patnaik) and T stage 0-1, I-1 (World Health Organization). Treated lesions were most commonly identified on the hindlimb and head where curative surgery would involve cosmetic or functional compromise. The intra-surgery group of dogs showed the best disease free interval with Kaplan-Meyer analysis. Local toxicity induced by ECT ranged mostly from 1 to 4 in a 5-point arbitrary scale with 0 - no toxicity to 5 - highest toxicity. In this study, ECT can be applied successfully as an exclusive therapy in smaller MCTs as an alternative to surgery. ECT can be combined with surgery either intra-operatively or post operatively for larger lesions without significant toxicity.

Electroporation in veterinary oncology.

Cancer treatments in veterinary medicine continue to evolve beyond the established standard therapies of surgery, chemotherapy and radiation therapy. New technologies in cancer therapy include a targeted mechanism to open the cell membrane based on electroporation, driving therapeutic agents, such as chemotherapy (electro-chemotherapy), for local control of cancer, or delivery of gene-based products (electro-gene therapy), directly into the cancer cell to achieve systemic control. This review examines electrochemotherapy and electro-gene therapy in veterinary medicine and considers future directions and applications.

Low immunogenicity in non-small cell lung cancer; do new developments and novel treatments have a role?

Approximately 1.6 million new cases of lung cancer are diagnosed annually (Jemal et al. CA: A Cancer Journal for Clinicians, 61, 69-90, 2011) and it remains the leading cause of cancer-related mortality worldwide. Despite decades of bench and clinical research to attempt to improve outcome for locally advanced, good performance status patients, the 5-year survival remains less than 15 % (Molina et al. 2008). Immune checkpoint inhibitor (ICH) therapies have shown a significant promise in preclinical and clinical trails to date in the treatment of non-small cell lung cancer (NSCLC). The idea of combining these systemic immune therapies with local ablative techniques is one that is gaining momentum. Electrochemotherapy (ECT) is a unique atraumatic local therapy that has had very promising objective response rates and a number of advantages including but not limited to its immunostimulatory effects. ECT in combination with ICHs offers a novel approach for dealing with this difficult disease process.

Non-viral immune electrogene therapy induces potent antitumour responses and has a curative effect in murine colon adenocarcinoma and melanoma cancer models.

Antitumour efficacy of electroporated pEEV, coding for granulocyte-macrophage colony-stimulating factor and the B7-1 costimulatory immune molecule (pEEVGmCSF-b7.1) in growing solid tumours, was investigated and compared with a standard plasmid. Application of pEEVGmCSF-b7.1 led to complete tumour regression in 66% of CT26-treated tumours and 100% in the B16F10-treated tumours at day 150 post-treatment. pEEVGmCSF-b7.1 treatment was found to significantly enhance levels of both innate and adaptive immune populations in tumour and systemic sites, which corresponded to significantly increased tissue levels of proinflammatory cytokines including interferon-γ (IFN-γ) and interleukin-12 (IL-12). In contrast, pEEVGmCSF-b7.1 treatment significantly reduced the T-regulatory populations and also the anti-inflammatory cytokine IL-10. Upon further characterisation of functional immune responses, we observed a significant increase in cytotoxic (CD107a+) and IFN-γ-producing natural killer cells and also significantly more in IL-12-producing B cells. Importantly, splenocytes isolated from pEEVGmCSF-b7.1-treated 'cured' mice were tumour-specific and afforded significant protection in a tumour rechallenge model (Winn assay). Our data indicate that electroimmunogene therapy with the non-viral pEEVGmCSF-b7.1 is able to induce potent and durable antitumour immune responses that significantly reduce primary and also secondary tumour growth, and thus represents a solid therapeutic platform for pursuing future clinical trials.

Enhancement of electroporation facilitated immunogene therapy via T-reg depletion.

Regulatory T cells (T-regs) can negatively impact tumor antigen-specific immune responses after infiltration into tumor tissue. However, depletion of T-regs can facilitate enhanced anti-tumor responses, thus augmenting the potential for immunotherapies. Here we focus on treating a highly aggressive form of cancer using a murine melanoma model with a poor prognosis. We utilize a combination of T-reg depletion and immunotherapy plasmid DNA delivered into the B16F10 melanoma tumor model via electroporation. Plasmids encoding murine granulocyte macrophage colony-stimulating factor and human B71 were transfected with electroporation into the tumor and transient elimination of T-regs was achieved with CD25-depleting antibodies (PC61). The combinational treatment effectively depleted T-regs compared to the untreated tumor and significantly reduced lung metastases. The combination treatment was not effective in increasing the survival, but only effective in suppression of metastases. These results indicate the potential for combining T-reg depletion with immunotherapy-based gene electrotransfer to decrease systemic metastasis and potentially enhance survival.

Electrochemotherapy for the treatment of ocular basal cell carcinoma; a novel adjunct in the disease management.

Basal Cell Carcinoma (BCC) affecting the ocular region is potentially problematic due to its ability to infiltrate aesthetic and functional structures. Due to the paucity of local tissue, resection frequently requires reconstruction with skin grafts or local flaps. Surgical treatment may not be suitable for patients with multiple co-morbidities. Electrochemotherapy (ECT) is a technique where cells are temporarily permeabilized after exposure to a brief electrical field and when combined with normally impermeant chemotherapy drugs can resolve cutaneous cancers - even those previously recalcitrant to chemotherapy or radiotherapy. Its particular advantage is its speed of application and the minimal damage to the surrounding healthy tissue structures. We present a series of 3 patients with BCCs in the peri-ocular region and significant co-morbidities deemed unsuitable for surgical resection, who underwent ECT. The lesions were all primary BCC ranging in size from 0.5 cm(2) to 1 cm(2). Two lesions were on the upper eyelid and one on the lower eyelid. ECT was performed using an 8-needle electrode and a CE approved electroporation generator with intra-lesional Bleomycin. All lesions responded to treatment. All BCC's completely resolved, with acceptable scarring. No side effects were reported from the Bleomycin or the electric pulses. ECT for peri-ocular BCC is an adjunct to surgical excision in the management of surgically problematic lesions. This technique could provide a useful initial treatment option for patients who are medically unfit or where resection and would be associated with significant morbidity.

Electrochemotherapy: technological advancements for efficient electroporation-based treatment of internal tumors.

Electrochemotherapy, a combination of high voltage electric pulses and of an anticancer drug, has been demonstrated to be highly effective in treatment of cutaneous and subcutaneous tumors. Unique properties of electrochemotherapy (e.g., high specificity for targeting cancer cells, high degree of localization of treatment effect, capacity for preserving the innate immune response and the structure of the extracellular matrix) are facilitating its wide spread in the clinics. Due to high effectiveness of electrochemotherapy in treatment of cutaneous and subcutaneous tumors regardless of histological origin, there are now attempts to extend its use to treatment of internal tumors. To advance the applicability of electrochemotherapy to treatment of internal solid tumors, new technological developments are needed that will enable treatment of these tumors in daily clinical practice. New electrodes through which electric pulses are delivered to target tissue need to be designed with the aim to access target tissue anywhere in the body. To increase the probability of complete tumor eradication, the electrodes have to be accurately positioned, first to provide an adequate extent of electroporation of all tumor cells and second not to damage critical healthy tissue or organs in its vicinity. This can be achieved by image guided insertion of electrodes that will enable accurate positioning of the electrodes in combination with patient-specific numerical treatment planning or using a predefined geometry of electrodes. In order to be able to use electrochemotherapy safely for treatment of internal tumors located in relative proximity of the heart (e.g., in case of liver metastases), the treatment must be performed without interfering with the heart's electrical activity. We describe recent technological advances, which allow treatment of liver and bone metastases, soft tissue sarcomas, brain tumors, and colorectal and esophageal tumors. The first clinical experiences in these novel application areas of electrochemotherapy are also described.

The emerging role of viruses in the treatment of solid tumours.

There is increasing optimism for the use of non-pathogenic viruses in the treatment of many cancers. Initial interest in oncolytic virotherapy was based on the observation of an occasional clinical resolution of a lymphoma after a systemic viral infection. In many cancers, by comparison with normal tissues, the competency of the cellular anti-viral mechanism is impaired, thus creating an exploitable difference between the tumour and normal cells, as an unimpeded viral proliferation in cancer cells is eventually cytocidal. In addition to their oncolytic capability, these particular viruses may be engineered to facilitate gene delivery to tumour cells to produce therapeutic effects such as cytokine secretion and anti -tumour immune responses prior to the eventual cytolysis. There is now promising clinical experience with these viral strategies, particularly as part of multimodal studies, and already several clinical trials are in progress. The limitations of standard cancer chemotherapies, including their lack of specificity with consequent collateral toxicity and the development of cross-resistance, do not appear to apply to viral-based therapies. Furthermore, virotherapy frequently restores chemoradiosensitivity to resistant tumours and has also demonstrated efficacy against cancers that historically have a dismal prognosis. While there is cause for optimism, through continued improvements in the efficiency and safety of systemic delivery, through the emergence of alternative viral agents and through favourable clinical experiences, clinical trials as part of multimodal protocols will be necessary to define clinical utility. Significant progress has been made and this is now a major research area with an increasing annual bibliography.

Effective immunotherapy of weakly immunogenic solid tumours using a combined immunogene therapy and regulatory T-cell inactivation.

Obstacles to effective immunotherapeutic anti-cancer approaches include poor immunogenicity of the tumour cells and the presence of tolerogenic mechanisms in the tumour microenvironment. We report an effective immune-based treatment of weakly immunogenic, growing solid tumours using a locally delivered immunogene therapy to promote development of immune effector responses in the tumour microenvironment and a systemic based T regulatory cell (Treg) inactivation strategy to potentiate these responses by elimination of tolerogenic or immune suppressor influences. As the JBS fibrosarcoma is weakly immunogenic and accumulates Treg in its microenvironment with progressive growth, we used this tumour model to test our combined immunotherapies. Plasmids encoding GM-CSF and B7-1 were electrically delivered into 100 mm(3) tumours; Treg inactivation was accomplished by systemic administration of anti-CD25 antibody (Ab). Using this approach, we found that complete elimination of tumours was achieved at a level of 60% by immunogene therapy, 25% for Treg inactivation and 90% for combined therapies. Moreover, we found that these responses were immune transferable, systemic, tumour specific and durable. Combined gene-based immune effector therapy and Treg inactivation represents an effective treatment for weakly antigenic solid growing tumours and that could be considered for clinical development.

Evaluation of cellular uptake and gene transfer efficiency of pegylated poly-L-lysine compacted DNA: implications for cancer gene therapy.

Recent success in phase I/II clinical trials (Konstan, M. W.; Davis, P. B.; Wagener, J. S.; Hilliard, K. A.; Stern, R. C.; Milgram, L. J.; Kowalczyk, T. H.; Hyatt, S. L.; Fink, T. L.; Gedeon, C. R.; Oette, S. M.; Payne, J. M.; Muhammad, O.; Ziady, A. G.; Moen, R. C.; Cooper, M. J. Hum. Gene Ther. 2004, 15 (12), 1255-69) has highlighted pegylated poly-L-lysine (C1K30-PEG) as a nonviral gene delivery agent capable of achieving clinically significant gene transfer levels in vivo. This study investigates the potential of a C1K30-PEG gene delivery system for cancer gene therapy and evaluates its mode of cellular entry with the purpose of developing an optimally formulated prototype for tumor cell transfection. C1K30-PEG complexes have a neutral charge and form rod-like and toroid-like nanoparticles. Comparison of the transfection efficiency achieved by C1K30-PEG with other cationic lipid and polymeric vectors demonstrates that C1K30-PEG transfects cells more efficiently than unpegylated poly-L-lysine and compares well to commercially available vectors. In vivo gene delivery by C1K30-PEG nanoparticles to a growing subcutaneous murine tumor was also demonstrated. To determine potential barriers to C1K30-PEG gene delivery, the entry mechanism and intracellular fate of rhodamine labeled complexes were investigated. Using cellular markers to delineate the pathway taken by the complexes upon cellular entry, only minor colocalization was observed with EEA-1, a marker of early endosomes. No colocalization was observed between the complexes and the transferrin receptor, which is a marker for clathrin-coated pits. In addition, complexes were not observed to enter late endosomes/lysosomes. Cellular entry of the complexes was completely inhibited by the macropinocytosis inhibitor, amiloride, indicating that the complexes enter cells via macropinosomes. Such mechanistic studies are an essential step to support future rational design of pegylated poly-L-lysine vectors to improve the efficiency of gene delivery.

Local gene therapy of solid tumors with GM-CSF and B7-1 eradicates both treated and distal tumors.

Gene therapy-induced expression of immunostimulatory molecules at tumor cell level may evoke antitumor immune mechanisms by recruiting and enhancing viability of antigen-processing cells and specific tumoricidal lymphocytes. The antitumor efficacy of a plasmid, coding for granulocyte-macrophage colony-stimulating factor (GM-CSF) and the B7-1 costimulatory immune molecule, delivered into growing solid tumors by electroporation was investigated. Murine fibrosarcomas (JBS) growing in Balb/C mice (

Non-viral in vivo immune gene therapy of cancer: combined strategies for treatment of systemic disease.

Many patients with various types of cancers have already by the time of presentation, micrometastases in their tissues and are left after treatment in a minimal residual disease state [Am J Gastroenterol 95(12), 2000]. To prevent tumour recurrence these patients require a systemic based therapy, but current modalities are limited by toxicity or lack of efficacy. We have previously reported that immune reactivity to the primary tumour is an important regulator of micrometastases and determinant of prognosis. This suggests that recruitment of specific anti-tumour mechanisms within the primary tumour could be used advantageously for tumour control as either primary or neo-adjuvant treatments. Recently, we have focused on methods of stimulating immune eradication of solid tumours and minimal residual disease using gene therapy approaches. Gene therapy is now a realistic prospect and a number of delivery approaches have been explored, including the use of viral and non-viral vectors. Non-viral vectors have received significant attention since, in spite of their relative delivery inefficiency, they may be safer and have greater potential for delivery of larger genetic units. By in vivo electroporation of the primary tumour with plasmid expressing GM-CSF and B7-1, we aim to stimulate immune eradication of the treated tumour and associated metastases. In this symposium report, we describe an effective gene based approach for cancer immunotherapy by inducing cytokine and immune co-stimulatory molecule expression by the growing cells of the primary tumour using a plasmid electroporation gene delivery strategy. We discuss the potential for enhancement of this therapy by its application as a neoadjuvant to surgical excision and by its use in combination with suppressor T cell depletion.

Combined electric field and ultrasound therapy as a novel anti-tumour treatment.

The permeabilising effects of electric pulses on cell membranes and the use of ultrasound energy of various intensities, for both thermal effects and enhancement of drug and gene delivery, have led to extensive research into the potential applications of these systems in the development of novel anti-cancer treatments. In the present study we have demonstrated for the first time that the application of brief electric pulses 'sensitises' tumour cells to the effects of low intensity ultrasound. The studies were conducted in human tumours established in athymic nude mice and in many instances resulted in the reduction of tumour mass. The combined electric field and ultrasound approach (CEFUS) was applied in vivo to a murine colon adenocarcinoma (C26) and a human oesophageal adenocarcinoma (OE19). The experiments performed demonstrated the anti-tumour effects of the combined therapy. Varying the electrosensitisation parameters used (voltage, waveform, electrode type) contributed to optimise the procedure. Exponential electric pulses with a peak of 1000 V/cm were initially used, but square wave pulses (1000 V/cm, 1 ms, x2, 1 Hz) were found to be just as effective. All ultrasound application parameters were kept constant during the study. The growth rate of C26 tumours treated with CEFUS was significantly reduced with respect to untreated controls at day 7 (96% of average initial tumour volume in CEFUS group versus 615% for controls, P < 0.05). Similar reduction was observed in OE19 tumours treated with CEFUS by day 4 (82% versus 232%, P < 0.032). Our preliminary data suggest that this novel technology could potentially be of wide application in clinical practice for the treatment of solid tumours and is worth further investigation.

The development of novel flexible electrode arrays for the electrochemotherapy of solid tumour tissue. (Potential for endoscopic treatment of inaccessible cancers).

Therapeutic "electroporation" involves application of electric fields to target cells/tissues, thereby rendering their cell membranes transiently porous, thus making feasible the cellular uptake and efficacy of previously impermeant and ineffective therapeutic agents. The objectives of this research are a) the development of flexible electrode arrays for incorporation into microsystem endoscopic devices, and b) the assessment of their efficacy in delivering selected genetic and pharmaceutical anticancer therapies. Gold electrodes were fabricated on flexible polyimide substrates following predictive modeling and simulation of electric fields using FEMLAB software. Subsequent assessment of electroporation efficiency in-vitro involved 1) enumeration of viable tumour cells after delivery of electric pulses and exposure to low concentrations of bleomycin, otherwise known as electrochemotherapy 2) Efficacy of gene delivery by detection of emitted green fluorescence by cells after electroporation with the pEGFP plasmid and 3) In-vivo efficacy of electrochemotherapy in a variety of human solid tumour masses in nude mouse models (xenografts). The flexible electrode system was found to be successful for electrical delivery of plasmids and drugs in-vitro and in-vivo. We found in-vivo complete regression of prostate, colon, oesophageal, and renal cancers with reduced growth rates for fibrosarcoma and breast cell lines. These flexible electrodes are suitable for electrochemotherapy or gene therapy to solid tumours masses and may be fabricated for application to the treatment of some cancers in humans by transcutaneous or endoscopic delivery systems.