REVIEW
A cura della Redazione della rivista “Medicina Multidisciplinare”

Electrochemotherapy with Intravenous Bleomycin in the Local Treatment of Skin Melanoma Metastases

P. Quaglino, MD ¹, C. Mortera, MD ¹ , S. Osella-Abate, PhD ¹, M. Barberis, MD ¹, M. Illengo, MD² , M. Rissone, MD ¹ , P. Savoia, MD ¹ and M. G. Bernengo, MD ¹

1 Department of Biomedical Sciences and Human Oncology, Section of Clinics and Oncological Dermatology, University of Turin, v. Cherasco 23, 10126 Torino, Italy
2 Section of Anaesthesia, San Giovanni Battista Hospital, Turin, Italy

Introduction

The treatment of skin metastases is still a challenge and depends on the size and number of lesions. In the presence of single or localized lesions, surgery is the treatment of choice.
Recently, electric pulses plus intralesional or intravenous bleomycin (electrochemotherapy, ECT) has been proposed as a new treatment modality for skin metastases of different malignancies including melanoma. The cell membrane barrier is efficiently permeabilized by electric pulses, allowing entry of molecules directly into the cytosol.
Only a few studies have specifically addressed the evaluation of the clinical activity of ECT in melanoma patients, most of them using intralesional bleomycin. Moreover, the majority of these studies were conducted on a limited number of cutaneous lesions and did not report complete follow-up data with response durations.

The study

In this paper, a series of 14 melanoma patients with a total of 233 cutaneous/subcutaneous metastases were treated with ECT using intravenous bleomycin under general sedation. The objectives of this study were to evaluate the clinical activity of intravenous bleomycin ECT in terms of response rates and response duration and to explore the potential therapeutic advantages of repeated ECT sessions.
Patient enrolment was carried out according to the following ESOPE criteria: histologically confirmed cutaneous melanoma, cutaneous and/or subcutaneous recurrent disease not amenable to surgery, measurable cutaneous and/or subcutaneous tumor nodules suitable for application of electric pulses, age ≥18 years, Karnowsky performance status ≥70, life expectancy at least 3 months, and a wash-out period of at least 3 weeks after the previous treatments.
Fourteen stage III patients were enrolled in the study. All had a cutaneous disease relapsed after one or more previous radical surgical treatments; moreover, four patients relapsed after isolated limb perfusion and two were treated with systemic chemotherapy. No patients had received bleomycin previously.

All treatments were carried out at 1st Dermatologic Clinic at the University of Turin using the Cliniporator™ device (IGEA, Modena, Italy) (Fig. 1).

FIG. 1. The electric pulse delivery unit Cliniporator™ (A) and the electrodes used: type I plate electrodes (B); needle electrodes type II, linear (C) and needle electrodes type III, exagonal (D). (Source: IGEA Clinical Biophysics Ltd., Modena, Italy).

All patients were treated under mild general anaesthesia that consisted of premedication with oral benzodiazepine (chlordemethyldiazepam), induction with a short-acting intravenous anaesthetic agent (propofol 2.5 mg/kg), inhalation of anaesthetic vapour (sevoflurane 2%), and assisted ventilation air/oxygen 40%. Postsurgical analgesia was provided by intravenous paracetamol (1 g).
Three different types of electrodes (IGEA, Modena, Italy) were used (Fig. 1). Type I electrodes are plate electrodes made up of two parallel stainless-steel plates with varying distances between 6 and 8 mm, used for the treatment of small superficial lesions without penetration of the skin.
Needle electrodes are suitable for treatment of thicker and deeper-seated tumor nodules: type II electrodes are made up of two parallel arrays of needles with a 4-mm gap between them for treatment of small nodules, whereas type III are a hexagonal array of electrodes (six needles forming a hexagon and one needle at its centre with an 8-mm gap between them) for larger nodules (>1 cm in diameter).

Cliniporator™ device  generates square-wave electric pulses of variable amplitude
with 1–5,000 Hz delivery frequencies. Intravenous bleomycin (15 mg/m²) was used in all cases, and administered in a time frame of 30 sec. to 1 min. Electric pulses were delivered from 8 until 28 min after bleomycin infusion to obtain an optimal response utilizing the most appropriate drug concentrations in tissues. A time interval of 20 min was enough to treat up to 30 lesions.
The response to treatment was scored 8 weeks after the ECT session. Response was classified in accordance with World Health Organization (WHO) guidelines as: progressive disease (PD) for increase in tumor size >25%; no change (NC) for increase in tumor size <25% or decrease <50%; partial response (PR) for decrease in tumor size >50% for at least 4 weeks; and CR for total clinical disappearance of the tumor.

Results

First ECT Session
A total of 14 stage III patients were enrolled. The response, scored 8 weeks after ECT, was obtained in 13/14 patients (93%) with a complete clinical regression of all skin metastases in seven (50%) and a PR in six patients. Only one patient did not respond. The clinical CR was confirmed by histology and immunohistochemistry in one index lesion from each patient. Figure 2 shows an example of complete response.
All the clinically detectable skin metastases were treated. The average number of lesions per patient was 10, for a total of 160 treated metastases; four patients had more than 20 lesions (21, 24, 26, and 29, respectively). An objective response was obtained in 153/160 (95%) lesions, with a CR rate of 62% (Table 1A). No differences in response rate were observed between cutaneous and subcutaneous metastases. The lesion size was the most predictive parameter for response. Indeed, a response was obtained in 123/124 (99%) metastases sized ≤1 cm² and in 30/36 (83%) larger lesions (X² = 13.2; p<0.001).
The differences in response rate was even higher when the CR rate was compared (72% in metastases ≤1 cm² versus 28% in >1 cm² lesions; X² = 21.1; p<0.001).

Repeated ECT Sessions
A further ECT session was performed in seven patients on 73 new metastases developed outside the initial treatment area (Table 1B). The ECT activity was maintained even if the response rate (86%) was significantly lower with respect to that obtained after the initial treatment (X² = 5.14, p = 0.023) due to a decreased response in >1 cm² sized metastases (X² = 5.0, p = 0.025).
Overall, 233 metastases were treated with a single ECT session. A size less than 1 cm² was observed in 184 (79%), with a median diameter of 7 mm (range 2–13 mm); 49 out of 233 metastases (21%) were >1 cm², with a median diameter of 15 mm (range 11–75 mm). The response rate obtained was 93% with a CR rate of 58% (Table 1). The response was 98% for lesions ≤1 cm² and 73% for lesions >1 cm² (X² = 30.43, p < 0.001); similarly, the CR rate was 68% and 22%, respectively (X² = 31.1, p<0.001).
Twenty-nine lesions from three patients (25 PR and 4 NC after the first ECT) underwent a second and five of them a third session in order to evaluate if the initial clinical response could be improved following re-treatment. A further response was obtained in 21/29 metastases (72%). Fifteen of the re-treated metastases were index lesions. Nine CRs were obtained, five in lesions sized >1 cm².

FIG. 2. The clinical (A), histological (B; hematoxylin and eosin) and immunohistochemical (C; HMB-45) picture before treatment in a female patient with numerous cutaneous in-transit metastases located to her left calf (note that all the lesions encircled received electric pulses): a complete clinical regression of all cutaneous metastases (D) was appreciated 2 months after the ECT course, confirmed by the disappearance of cutaneous HMB-45+ melanoma cells (E, histology; F, immunohistochemistry).

TABLE 1. ECT response rates in metastases treated with a single ECT session

Response Duration
None of the metastases that achieved a CR relapsed after a median follow-up of 21 months (range 5–28 months); on the other hand, 54/80 PR lesions showed a >25% size increase. At 2 years, the local tumor control rate was 74.5% (Fig. 3);

FIG. 3. Local tumor control curve (number of treated lesions n = 233).

Side Effects
Erythema and slight oedema occurred at the site of treated lesions in three patients and disappeared within a few days. Moreover, marks from the electrodes and superficial epidermal erosions were noted in all cases, followed by scars healing within a month of ECT. Patients did not report local pain or other subjective symptoms. No haematologic toxicity was observed.

Discussion

The unique feature of this study population are represented by the high number of treated lesions (n = 233) and the sequential administration of ECT sessions to the same patient on residual metastases. Also the follow-up time (median 21 months) is longer than those reported in literature; for comparison, the median follow-up reported in the ESOPE study was 4.5 months.

The results obtained strongly support the clinical activity and tolerability of ECT performed with i.v. bleomycin under general sedation according to the treatment modality D of the ESOPE standard operating procedures.

A response was obtained in 93% of treated lesions, among which 58% showed a CR histologically confirmed in index lesions. The relevance of achieving CR is underlined by the evidence that none of the CR lesions relapsed during the follow-up, as already reported by other authors; overall the local tumor control was 74.5% at 2 years. The responses were also obtained in four patients that had relapsed after isolated antiblastic limb perfusion and in the two who were refractory to chemotherapy alone. The ECT clinical activity clearly indicates a specific role for this procedure in the treatment strategies of stage III melanoma patients with small cutaneous metastases that are not surgically manageable.

 The higher response rate (RR) and response durations obtained by ECT with respect to standard chemotherapy strongly emphasize the relevance of electroporation in the enhancement of chemotherapeutic agent delivery into poorly permeant cells. Nowadays, bleomycin alone is not used in clinical practice given the very low percentage of response reported in the literature.

ECT is easily manageable in terms of local and systemic toxicities and cost-effectiveness ratios. Moreover, the general sedation for ECT is mild, with lower duration, analgesic support, and complication rate compared with those required for ILP, thus allowing ECT sessions to be performed at shorter intervals in time.
Future studies should be directed towards the identification of other and more effective drugs to be delivered in association with electric pulses. In addition, adjuvant treatment strategies with new agents (immunomodulators, anti-angiogenetic, monoclonal antibodies) could be administered after the ECT sessions in an attempt to reduce the emerge