ABSTRACT

Solasodine rhamnosyl glycosides (SRGs) are chemotherapeutic agents for the treatment of cancer. SRGs in a cream formulation, Curaderm^BEC5, is very effective for the treatment of nonmelanoma skin cancers with excellent cosmetic end results. Intralesion injection of SRGs successfully dispose of very large tumours in animals without any clinical adverse effects. The mode of action of SRGs is by apoptosis. In this study, it is shown that small to large basal cell carcinomas are effectively treated only with topical application of Curaderm^BEC5. Here it is reported for the first time that combination of intralesion SRG injection and topical application with Curaderm^{BEC5 in humans reduces the treatment time period by more than half when compared with topical application as the sole treatment regime. Two intralesion injections of very low doses of SRGs rapidly and effectively remove a large melanoma on a horse. If rapid removal of large troublesome skin cancers is required then this can be achieved by intralesion and topical treatments. Intralesion or combination therapy with SRGs may have some applications for melanomas in situ such as lentigo maligna.}

1. Introduction

Existing antimitotic chemotherapeutic agents appear to affect fast growing cells by killing such cells when they are dividing (proliferating cells). When such cells are not dividing (non-proliferating cells) the existing antimitotic chemotherapeutic agents have very limited effects upon these cells. Consequently, the time course for treating cancer cells with existing antimitotic chemotherapeutic agents is long and repetitive treatments are required. In addition, certain cancers have developed drug-resistance which seriously complicates antimitotic therapy. The side effects of antimitotic chemotherapy are well know.

Solasodine rhamnosyl glycosides (SGRs) are very promising antineoplastics [1-24]. Oral, intravenous, intraperitoneal and intralesion studies with these glycoalkaloids have been described [13,19-21,25]. Many studies have reported the high antineoplastic efficacy, low toxicity of solamargine, solasonine and a constant mixture of these glycoalkaloids (BEC) [4-25].

Unlike established antimitotic drugs, BEC and its individual glycoalkaloids, solamargine and solasonine, are not antimitotic in their actions [21,24,26-30]. BEC induces apoptosis in cancer cells by up-regulating the expressions of external death receptors, such as tumour necrosis factor receptor 1 (TNFR-1), Fas receptor, TNFR-1 associated death domain and Fas-associated death domain. BEC also enhances the intrinsic ratio of Bax to Bcl-2 by up-regulating Bax and down-regulating Bcl-2 and Bcl-xL expressions. These effects result in activation of Caspase –8, –9 and –3 in cancer cells, indicating that BEC triggers extrinsic and intrinsic apoptotic pathways in cancer cells [7,21,22,26-32].

Solamargine, the main component of BEC, also kills cancer cells by oncosis. After interaction of solamargine with cancer cells, marked changes in cell shape and volume occur. The cells get blebs on the membrane, the mitochondria swell, the contents of the nuclei clump and the cells die. It has been proposed that apoptosis and oncosis share certain mechanisms and alterations within the cell before they die by bursting. At low concentrations solamargine kills cancer cells by apoptosis and at higher doses, solamargine kills cancer cells by oncosis, and both types of cell death are induced by intermediate concentrations of solamargine [32].

It has recently been shown that, in addition to causing apoptosis in cancer cells, intralesion administration of BEC also stimulates lasting immunity against cancer [24].

Intravenous (i.v.) administrations of drugs pose a number of serious limitations including toxicity to body organs. Because of the dilution effect of the drug within the vascular system and the pharmacokinetics of the drug by various body organs, a relatively high dose of the drug has to be administered frequently for it to have a therapeutic effect on the targeted cancer cells and this high dose may result in serious toxicological effects. Intravenous doses are dependent on body weight or volume. It was shown that intralesion injection of BEC is far superior to i.v. injection if the targeted lesion being treated is rapidly and specifically degraded by the chemotherapeutic agent. Intralesion injections of very low doses of BEC into large chondrosarcomas and squamous cell carcinomas in animals completely eliminate these tumours. The required dose of intralesion injections are tumour weight dependent and not body weight dependent and are 100 times lower than for i.v. infusions [21].

Curaderm^BEC5 is a topical cream which contains a mixture of solasodine glycosides (BEC) and is very effective for treating nonmelanoma skin cancers. Advantages of treatment of these lesions with Curaderm^BEC5 compared with well established surgical interventions and other therapies have previously been reported [1-3,19,20,24,28,29,33-37].

The treatment time period with topical Curaderm^BEC5 to completely eliminate skin cancers varies from days to months depending on size and type of skin tumours. Large nonmelanoma skin cancers can successfully be treated with Curaderm^BEC5 and it may take several months of treatment to eliminate these large tumours [1-3,19,20,24, 28,29,33,33-37].

The incidences of nonmelanoma skin cancers such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) have increased more than 300 percent since 1992 [1,2,38]. For malignant melanoma, increased rates of over 500 percent have been reported from 1975 to 2008 [1,39].

Limitations and costs of current treatments for skin cancers pose many shortfalls and many patients afflicted with these diseases do not seek proper treatment, resulting in increased morbidity and mortality [1,3,40,41].

This report describes the successful treatments of various large BCCs by topical application of a cream formulation. Combination therapy of intralesion and topical application of the same antineoplastic agents, BEC, result in rapid removal of a large BCC. Combination therapy of intralesion and topical treatment of BEC reduces skin cancer treatment period by about half when compared with topical treatment alone. The cosmetic end results of the treatments are excellent.

This report also shows that intralesion injection of BEC alone, without Curaderm^BEC5 cream combination therapy, into a large melanoma of a horse results in the elimination of this potentially deadly skin cancer.

2. Materials and Methods

2.1. Patient Selection

A 68 year old farmer was referred for consultation because he had multiple basal cell carcinomas of varying sizes. In particular, he also had a very large BCC on his back that often bled and was painful. This large BCC was a recurrence of a smaller BCC that was previously removed surgically with the involvement of a skin flap. The patient who had these lesions for several years elected to treat various lesions with the cream formulation Curaderm^BEC5. However, because of the size and pain associated with the large BCC, he requested to have this lesion treated by intralesion injection using the active ingredients solasodine glycosides (BEC) which are also present in the Curaderm^BEC5 cream formulation. Patient’s informed consent for the treatment was obtained.

The sizes of the BCCs ranged from less than 2 cm in diameter (6 lesions) to approximately 3 cm × 3 cm × 0.5 cm (4 lesions) to 5 cm × 5 cm × 1.5 cm (1 lesion). Histological analyses of biopsies revealed that these lesions were BCCs.

A horse had an histologically diagnosed melanoma on the chest. This lesion was present for at least six months. The surface area of the lesion measured 5 cm × 4 cm and protruded approximately 1 cm. The owner of the horse was referred to our centre by his veterinarian and requested treatment with BEC for his horse’s melanoma.

2.2. Treatments Administered

2.2.1. BEC—Solasodine Rhamnosyl Glycosides

Glycoalkaloids (BEC) were extracted from the fruit of S. sodomaeum also known as S. linnaeanum (devil’s apple) and S. melongena (eggplant) essentially as described earlier [42]. BEC is a mixture of solasodine glycosides consisting of the triglycosides solasonine (β-solatriose) (33%), solamargine (β-chacotriose) (33%), and di-and monoglycosides (34%). All the glycosides contain the same aglycone, solasodine [2,4,5,24,28,42]. Figure 1 shows the chemical structures of solasonine and solamargine [2,4,5,24, 28,42] and Figure 2 shows their mass spectra [2,24]. In the present studies the extract containing the mixture of these glycoalkaloids was investigated. Just prior to the current set of experiments BEC was analyzed by HPLC [24,42] and it was shown to consist of 33% solasonine, 33% solamargine and 34% of diand monoglycosides of solasodine.

2.2.2. Curaderm^BEC5 Topical Cream Formulation

The cream formulation Curaderm^BEC5 is available to patients in several countries. Curaderm^BEC5 contains the glycoalkaloids BEC at 0.005% as a topical cream formulation. The cream was applied twice daily (when possible every 12 hours) under occlusive dressing (micropore paper tape) until the lesion had clinically regressed [1,41].

2.2.3. BEC in DMSO Solution for Intralesion Injection

A sterile solution of 10% BEC in dimethylsulfoxide, w/w, was used in this study [21].

The weight of the large BCC on the back of the human was approximately 50 g. The doses injected intralesionally were approximately 100 mg BEC per 1 kg tumour weight [21]. In the human subject, with the BCC tumour weight of approximately 50 g, the dose was 50 microlitres of the 10% BEC solution and for the horse, with the melanoma tumour weight of 25 g, the dose was 25 microlitres of the 10% BEC solution.

The human and horse were injected intralesionally on 2 separate occasions. The second injection occurred approximately 48 hours after the first injection. Each injection was done intralesionally on multiple sites of the tumour including at the juncture of the lesions with the surrounding normal skin. No anaesthetic was used during the treatment regimes.

3. Results

The patient had several BCCs that were treated only with the topical cream formulation Curaderm^BEC5. The six BCC lesions which were less than 2 cm in diameter all regressed after 6 weeks with Curaderm^BEC5 topical treatment (not shown).

Figure 3(a) shows a BCC before Curaderm^BEC5 topical treatment. The lesion’s size was approximately 3 cm × 4 cm and protruded 0.5 cm from the skin’s surface. Figure 3(b) shows that the lesion was reduced considerably after six weeks of treatment. Figure 3(c) shows that the lesion was completely ablated 16 weeks after commencement of Curaderm^BEC5 therapy.

Similarly, Figure 4 shows another BCC of approximately 3 cm × 3 cm × 0.5 cm before (Figure 4(a)), six weeks during treatment (Figure 4(b)). After 16 weeks the lesion had clinically regressed (Figure 4(c)).

Figure 5(a) illustrates what appears to be three indi vidual BCCs. Closer clinical examination revealed that the three BCC lesions were interconnected. Six weeks of topical Curaderm^BEC5 therapy resulted in the erosion of the entire area (4 cm × 4 cm) including the spaces between the previously apparent distinctive lesions (Figure 5(b)). After 16 weeks there was no evidence of residual tumour (Figure 5(c)).

Figures 6(a) and (b) show a raised BCC of approximately 3 cm × 3 cm × 1 cm before Curaderm^BEC5 treatment. Six weeks of treatment resulted in haemorrhagic necrosis of the tumour mass (Figure 6(c)) and 16 weeks after commencement of treatment, complete remission had occurred (Figure 6(d)).

Clinical evaluation indicated that the lesions of Figures 3-6 were eliminated 14 weeks after topical Curaderm^BEC5 treatments. The cosmetic end results, as shown at 16 weeks after commencement of treatments, were outstanding and there were no scar tissues at the sites of the treated lesions. During the first week of treatment, the patient experienced a stinging to mild burning sensation which lasted for approximately 20 minutes after topical application of Curaderm^BEC5.

Figure 7(a) shows a large 5 cm × 5 cm BCC before combination treatment with intralesion injection followed by Curaderm^BEC5 topical treatment. Figure 7(b) illustrates that this lesion protruded 1.5 cm from the skin’s surface. Two days after the first injection of BEC in DMSO, but before the second injection, the lesion had already started to breakdown (Figure 7(c)). The odour of DMSO and necrosing tissue were noticeable. Two days after the second and final injection of BEC in DMSO, the necrosing lesion had released itself from the skin Figure 7(d). The patient experienced some pain when BEC in DMSO was