The treatment of melanoma with an emphasis on immunotherapeutic strategies

Rationalizing a prospective coupling effect of cannabinoids with the current pharmacotherapy for melanoma treatment

Melanoma is one of the leading fatal forms of cancer, yet from a treatment perspective, we have minimal control over its reoccurrence and resistance to current pharmacotherapies. The endocannabinoid system (ECS) has recently been accepted as a multifaceted homeostatic regulator, influencing various physiological processes across different biological compartments, including the skin. This review presents an overview of the pathophysiology of melanoma, current pharmacotherapy used for treatment, and the challenges associated with the different pharmacological approaches. Furthermore, it highlights the utility of cannabinoids as an additive remedy for melanoma by restoring the balance between downregulated immunomodulatory pathways and elevated inflammatory cytokines during chronic skin conditions as one of the suggested critical approaches in treating this immunogenic tumor. This article is categorized under: Cancer > Molecular and Cellular Physiology.

Female genital tract melanoma: Analysis from a regional cancer institute

Objective:

Malignant melanoma of the genital tract comprises 3% of all melanomas afflicting females. They are characterized by poor prognosis with 5-year survival of 0-25% and high incidence for distant metastasis. This study was performed to assess various clinical features, treatment options, and thre management of genital melanomas.

Materials and Methods:

This was a retrospective analysis where records of patients with genital melanomas between 2005 to 2018 were reviewed to obtain demographic and clinical information, including age of diagnosis, presenting symptoms, performance status, pathology reports, treatment, follow-up, and survival.

Results:

Between 2005 and 2018, 31 women were analyzed. The median age was 53.5 (range: 28.5-85) years. Vaginal bleeding was the most common presenting symptom (80.6%), followed by discharge (29%), mass in the vagina/perineum (19.3%), pain (16.1%), and difficulty in micturition (9.6%). The most common site of origin was the vagina (67.7%), followed by that vulva (19.3%) and cervix (12.9%). Tumor diameter was more than 3 cm in 74.2% (23/31). Out of 31 patients, only 16 opted for treatment. Four patients underwent surgery, 10 received primary chemotherapy, and two needed palliative radiotherapy for heavy bleeding. The median survival in the treatment group was 5 (range: 2.5-28) months, almost similar to patients not receiving any treatment (5 months, range: 2-11).

Conclusion:

Genital melanoma are rare but aggressive tumors. Diagnosis is usually made with biopsy. No effective treatment strategy is yet available. However, surgery is the preferred first- line treatment, radiotherapy and chemotherapy have been used in adjuvant settings.

Vaginal primary malignant melanoma: a rare and aggressive tumor

Vaginal primary malignant melanoma is a rare and very aggressive tumor. It most commonly occurs in postmenopausal women, with a mean age of 57 years. Our patient is an 80-year-old, postmenopausal Greek woman presented with a complaint of abnormal vaginal bleeding. On gynecologic examination there was a pigmented, raised, ulcerated, and irregular lesion 5 × 4.5 cm in the upper third of anterior vaginal wall. She underwent a wide local excision of the lesion. The histopathology revealed vaginal primary malignant melanoma with ulceration and no clear surgical margins. She denied any additional surgical interventions and underwent to postoperative adjuvant radiotherapy. Follow up 5 months after initial diagnosis revealed no evidence of local recurrence or distant metastasis. The prognosis of vaginal primary malignant melanoma is very poor despite treatment modality, because most of the cases are diagnosed at advanced stage. Particularly patients with no clear surgical margins and tumor size >3 cm needed postoperative adjuvant radiotherapy.

Immunotherapy for cutaneous malignancy

BACKGROUND

Immunotherapy for cutaneous malignancy involves manipulating the immune system to treat and prevent skin cancer. Although initial efforts were fraught with low success rates and technical challenges, more-recent endeavors have yielded response rates approaching 50% for treating metastatic melanoma. Many of these advances are a result of increasing knowledge of the immune system's intricacies and continued progress in laboratory techniques.

OBJECTIVE

To review our current understanding of the skin immune system and discuss how these factors contribute to the host response to malignancy and to report the current state of immunotherapeutic techniques.

MATERIALS AND METHODS

An extensive PubMed literature search was conducted in topics involving immunotherapy with specific relevance to cutaneous malignancy using the MeSH terms "immunotherapy" and "skin cancer."

RESULTS

Despite initially poor patient responses to these treatment modalities, recent gains in scientific knowledge and clinical intervention protocols have brought immunotherapy to the forefront of prospective skin cancer therapeutics, particularly for advanced melanoma.

CONCLUSIONS

Current treatment options for advanced cutaneous malignancies such as melanoma are low in efficacy. Immunotherapies have the potential to provide novel approaches to address this, particularly when used in combination. The authors have indicated no significant interest with commercial supporters.

Circulating tumor cells in melanoma: a review of the literature and description of a novel technique

Melanoma is a prevalent and deadly disease with limited therapeutic options. Current prognostic factors are unable to adequately guide treatment. Circulating tumor cells are a disease-specific factor that can be used as a prognostic variable to guide therapy. Most research to date has focused on identification of circulating tumor cells using various methods, including polymerase chain reaction. These techniques, however, have poor sensitivity and variable specificity and predictive significance. A recently developed technology to identify circulating tumor cells is the CellSearch system. This system uses immunomagnetic cell labeling and digital microscopy. This technology may provide an alternative method to identify circulating tumor cells in patients with advanced-stage melanoma and function as a prognostic factor. We review the literature on circulating tumor cells in melanoma and present data collected at our institution using the CellSearch system in nine patients with stage III or IV melanoma.

Genetic factors in metastatic progression of cutaneous melanoma: the future role of circulating melanoma cells in prognosis and management

The greatest potential for improvement of outcome for patients with Cutaneous Malignant Melanoma lies in the prevention of systemic metastasis. Despite extensive investigation, current prognostic indicators either alone or in combination, although related to melanoma progression, are not sufficient to accurately predict the pattern of progression and outcome for any individual patient. Metastasis related death has been recorded in patients initially diagnosed with early stage tumour as well as in patients many years after initial tumour removal. The trouble finding a predictable pattern in the puzzle of melanoma progression may be linked to the fact that most of the material studied for prognosis is either, cutaneous primaries or metastatic deposits, rather than the melanoma cells in the circulatory system which are responsible for disease progression. In this review article we discuss the potential use of circulating tumour cell (CTC) detection and quantification for identifying patients at risk of metastatic deposits. We also discuss current therapies for the treatment of metastatic melanoma and analyse how CTCs may be used to evaluate the effectiveness of current therapies and to pinpoint patients who require further treatment.

Reactive oxygen species and melanoma: an explanation for gender differences in survival?

Epidemiological research consistently shows a female advantage in melanoma survival. So far, no definite candidate for the explanation of this phenomenon has emerged. We propose that gender differences in oxidative stress caused by radical oxygen species (ROS) underlie these survival differences. It is known that males express lower amounts of anti-oxidant enzymes, resulting in more oxidative stress than females. The primary melanoma environment is characterized by high ROS levels, from exogenous sources as well as ROS production within melanoma cells themselves. ROS are known to be able to promote metastasis through a wide variety of mechanisms. We hypothesize that the higher levels of ROS in men enhance selection of ROS-resistance in melanoma cells. Subsequently, ROS can stimulate the metastatic potential of melanoma cells. In addition, due to the lower anti-oxidant defenses in men, ROS produced by melanoma cells cause more damage to healthy tissues surrounding the tumor, further stimulating metastasis. Therefore, ROS may explain the observed differences between males and females in melanoma survival.

Results of a multicenter, randomized, double-blind phase 2/3 study of lenalidomide in the treatment of pretreated relapsed or refractory metastatic malignant melanoma

BACKGROUND

The results of an international, multicenter, randomized, double-blind, controlled study assessing the efficacy and safety of lenalidomide treatment in patients with refractory stage IV metastatic malignant melanoma are reported.

METHODS

The study compared treatment with lenalidomide (25 mg/d on Days 1-21 of a 28-day cycle) to placebo in 306 patients with metastatic malignant melanoma. Treatment was continued until progression of disease or unacceptable toxicity.

RESULTS

There were no significant differences between lenalidomide and placebo in overall survival (median 5.9 months vs 7.4 months, respectively; P = .32), time to progression (median 3.0 months vs 2.1 months; P = .19), or Response Evaluation Criteria in Solid Tumors tumor response (5.3% vs 5.8%; P = .82). None of the patients given placebo discontinued treatment because of treatment-related adverse events, compared with 4.6% of those treated with lenalidomide. Treatment-related myelosuppression was observed in 2.0% of patients treated with placebo and 7.3% of patients treated with lenalidomide.

CONCLUSIONS

This study showed that treatment with lenalidomide (25 mg/d) has a manageable safety profile in patients with previously treated metastatic malignant melanoma but no benefit in tumor response, time to progression, or overall survival in these patients. Future trials for treatment of metastatic malignant melanoma with lenalidomide should focus on its use in combination therapies.

NKG2D ligands in tumor immunity

The activating receptor NKG2D (natural-killer group 2, member D) and its ligands play an important role in the NK, gammadelta(+) and CD8(+) T-cell-mediated immune response to tumors. Ligands for NKG2D are rarely detectable on the surface of healthy cells and tissues, but are frequently expressed by tumor cell lines and in tumor tissues. It is evident that the expression levels of these ligands on target cells have to be tightly regulated to allow immune cell activation against tumors, but at the same time avoid destruction of healthy tissues. Importantly, it was recently discovered that another safeguard mechanism controlling activation via the receptor NKG2D exists. It was shown that NKG2D signaling is coupled to the IL-15 receptor pathway in a cell-specific manner suggesting that priming of NKG2D-mediated activation depends on the cellular microenvironment and the distinct cellular context. This review will provide a broad overview of our up-to-date knowledge of the NKG2D receptor and its ligands in the context of tumor immunology. Strategies to amplify NKG2D-mediated antitumor responses and counteract tumor immune escape mechanisms will be discussed.

The role of vaccine therapy in the treatment of melanoma

BACKGROUND

Melanoma is a tumour that is usually resistant to systemic therapy. Since it has been considered to be a highly immunogenic tumour, it has become an excellent target for the active specific immunotherapy. Vaccine therapy represents a novel approach to the treatment of melanoma.

OBJECTIVE

To evaluate different vaccines tested in stage III and/or IV melanoma patients.

METHODS

Systematic review of the published evidence on vaccine therapy in melanoma.

RESULTS

Melanoma vaccines can be classified into six groups: whole-cell vaccines, dendritic cell vaccines, peptide vaccines, ganglioside vaccines, DNA vaccines and viral vectors. The main characteristics of these vaccines including their advantages and disadvantages and the results from conducted trials are presented. Clinical responses to melanoma vaccines are still poor and currently there is no melanoma vaccine with a proven efficacy.

CONCLUSION

Vaccine therapy still remains an experimental therapy in patients with metastatic melanoma. Further research is required although a future therapy for advanced melanoma is probably a multimodal approach including vaccines, adjuvants and negative co-stimulatory blockade.

Topical interferon alfa in the treatment of conjunctival melanoma and primary acquired melanosis complex

PURPOSE

To report on topical interferon alfa-2b for conjunctival malignant melanoma (CMM) and primary acquired melanosis with atypia (PAM).

DESIGN

Retrospective, interventional case series.

METHODS

Five eyes of five consecutive patients with biopsy-proven malignant melanoma were treated with topical interferon alfa-2b as treatment for primary or recurrent disease. One drop of interferon alfa-2b (1 million units/ml) was placed into the superior fornix four times daily for three months. Punctal plugs limited systemic absorption. The main outcome measure was tumor regression by clinical examination and comparative slit-lamp photography.

RESULTS

Five consecutive patients with conjunctival melanoma (American Joint Committee on Cancer-International Union Against Cancer stages T2 [n = 3] and T3 [n = 2]) were included. Two patients had recurrent corneal tumors, eight and 13 months after local excision, cryotherapy, and topical mitomycin C therapy. Two months after topical interferon alfa-2b treatment, the lesions regressed without side effects. Two additional patients (who could not tolerate topical mitomycin C) were switched to topical interferon alfa-2b. They experienced transient chemical conjunctivitis and have no signs of recurrence (mean, 15 months of follow-up). The fifth had recurrent tumor despite multiple surgeries. This melanoma did not respond to topical interferon alfa-2b nor did the patient tolerate treatment (keratoconjunctivitis). No systemic side effects were noted.

CONCLUSIONS

We present evidence that conjunctival and corneal melanoma regresses after exposure to topical interferon alfa-2b. A larger-scale longer-term study must evaluate the long-term efficacy and safety of this therapy.

Early experience with novel immunomodulators for cancer treatment

Immunotherapy involves the treatment of cancer by modification of the host-tumour relationship. It is now known that this relationship is quite complex and only some of the interactions have been elucidated. Early attempts at immunotherapy, such as Coley's toxins, were undertaken without an understanding of the processes mediating the effects. With a better understanding of the immunology of this anticancer response, recent trials have focussed on certain aspects of the process to stimulate an antitumour response. In this review, the authors discuss a number of novel biological response modifiers that work as general stimulants of the immune system, through varied mechanisms including induction of stimulatory cytokines (such as IFN-alpha, TNF-alpha and IL-12) and activation of T cells and the antigen-presenting dendritic cells. These compounds include Toll-like receptor agonists, several of which are in clinical trials at present. In addition to immunomodulatory activity, some compounds such as 5,6-dimethylxanthenone-4-acetic acid (DMXAA) and thalidomide and its analogues also target existing or developing tumour vasculature. Some of these compounds have single-agent activity in clinical trials, while others such as DMXAA have shown promise in combination with chemotherapy without increasing toxicity. Lactoferrin is another compound that has shown clinical activity with low toxicity. At present, accepted indications for immunotherapy are limited to a few cancers such as renal cell carcinoma and melanoma. This paper looks at some of the reasons for the limited impact of immunotherapy so far and suggest possible avenues for further research with a greater likelihood of success.

Melanoma induces immunosuppression by up-regulating FOXP3(+) regulatory T cells

BACKGROUND

The immune response to melanoma is rarely curative, suggesting the emergence of immunosuppression. FOXP3-expressing regulatory T cells (T(reg) cells) function to suppress immune responses. The objective of this study was to determine if melanoma evades immune surveillance, in part, by inducing T(reg) cells.

MATERIAL AND METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated and exposed to melanoma-conditioned media (MCM) or control media for 1 week. The induction of T(reg) cells in these PBMCs was determined by measuring the proportion of CD25(+)FOXP3(+) T cells in all CD4(+) T cells by flow cytometry. FOXP3 expression was determined by mean fluorescence intensity (MFI) and Western blot. Supernatant cytokines were determined by ELISA.

RESULTS

Normal PBMCs exposed to MCM revealed higher proportions of T(reg) cells than those exposed to control media after 6 days (3.4% versus 1.3%, respectively, P < 0.02). The expression of FOXP3 in T(reg) cells from PBMCs exposed to MCM increased over time by MFI and Western blot but was not significantly different than those exposed to control media. The level of IL-10 and TGF-beta in supernatants after 6 days growth was higher in MCM than control media, but this did not reach statistical significance.

CONCLUSION

Exposure of PBMCs to melanoma results in induction of FOXP3(+) T(reg) cells.