Immunotherapy of Melanoma

Synergistic effects of radiotherapy and targeted immunotherapy in improving tumor treatment efficacy: a review

Radiotherapy (RT), unlike chemotherapy, is one of the most routinely used and effective genotoxic and immune response inducing cancer therapies with an advantage of reduced side effects. However, cancer can relapse after RT owing to multiple factors, including acquired tumor resistance, immune suppressive microenvironment buildup, increased DNA repair, thus favoring tumor metastasis. Efforts to mitigate these undesirable effects have drawn interest in combining RT with immunotherapy, particularly the use of immune checkpoint inhibitors, to tilt the pre-existing tumor stromal microenvironment into long-lasting therapy-induced antitumor immunity at multiple metastatic sites (abscopal effects). This multimodal therapeutic strategy can alleviate the increased T cell priming and decrease tumor growth and metastasis, thus emerging as a significant approach to sustain as long-term antitumor immunity. To understand more about this synergism, a detailed cellular mechanism underlying the dynamic interaction between tumor and immune cells within the irradiated tumor microenvironment needs to be explored. Hence, in the present review, we have attempted to evaluate various RT-inducible immune factors, which can be targeted by immunotherapy and provide detailed explanation to optimally maximize their synergy with immunotherapy for long-lasting antitumor immunity. Moreover, we have critically assessed various combinatorial approaches along with their challenges and described strategies to modify them in addition to providing approaches for optimal synergistic effects of the combination.

Targeting regulatory T cells for immunotherapy in melanoma

Regulatory T cells (Tregs) are essential in the maintenance of immunity, and they are also a key to immune suppressive microenvironment in solid tumors. Many studies have revealed the biology of Tregs in various human pathologies. Here we review recent understandings of the immunophenotypes and suppressive functions of Tregs in melanoma, including Treg recruitment and expansion in a tumor. Tregs are frequently accumulated in melanoma and the ratio of CD8+ T cells versus Tregs in the melanoma is predictive for patient survival. Hence, depletion of Tregs is a promising strategy for the enhancement of anti-melanoma immunity. Many recent studies are aimed to target Tregs in melanoma. Distinguishing Tregs from other immune cells and understanding the function of different subsets of Tregs may contribute to better therapeutic efficacy. Depletion of functional Tregs from the tumor microenvironment has been tested to induce clinically relevant immune responses against melanomas. However, the lack of Treg specific therapeutic antibodies or Treg specific depleting strategies is a big hurdle that is yet to be overcome. Additional studies to fine-tune currently available therapies and more agents that specifically and selectively target tumor infiltrating Tregs in melanoma are urgently needed.

Update on vaccines for high-risk melanoma

The management of high-risk melanoma has historically included primary surgical resection with or without lymphadenectomy followed by an array of adjuvant options including radiation therapy or immunomodulatory therapies such as interferon-α, granulocyte macrophage colony-stimulating factor, and a multitude of vaccines. There has been a long-standing interest in the development of vaccines in high-risk and metastatic melanoma, and clinical trials have been ongoing for decades. Given that melanoma is identified as one of the most immunogenic solid tumors, there is continued hope that vaccine therapies will improve clinical outcomes. Despite intense interest in this field, few clinical trials to-date have demonstrated significant benefit from melanoma vaccines in high-risk disease. Several trials have even documented a detrimental effect on outcomes after vaccine administration. While the role of vaccines in the adjuvant setting of high-risk melanoma presently remains unclear, recent advances in immunotherapy for melanoma including development of cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programmed cell death 1 (PD-1) monoclonal antibodies have demonstrated meaningful clinical responses. With further study and focus on mechanisms of immune regulation, there remains promise for the role of vaccines in combination with other immune-stimulatory agents in high-risk melanoma.

Cutaneous melanoma: new advances in treatment

Cutaneous melanoma is a challenge to treat. Over the last 30 years, no drug or combination of drugs demonstrated significant impact to improve patient survival. From 1995 to 2000, the use of cytokines such as interferon and interleukin become treatment options. In 2011, new drugs were approved by the U.S. Food and Drug Administration, including peginterferon alfa-2b for patients with stage III disease, vemurafenib for patients with metastatic melanoma with the BRAF V600E mutation, and ipilimumab, a monoclonal antibody directed to the CTLA-4 T lymphocyte receptor, to combat metastatic melanoma in patients who do not have the BRAF V600E mutation. Both ipilimumab and vemurafenib showed results in terms of overall survival. Other trials with inhibitors of other genes, such as the KIT gene and MEK, are underway in the search for new discoveries. The discovery of new treatments for advanced or metastatic disease aims to relieve symptoms and improve patient quality of life.

Management of primary cutaneous and metastatic melanoma

OBJECTIVES

To review the diagnosis, staging, and treatments (both standard and novel) for advanced melanoma and discuss the nursing role in the care of patients with melanoma.

DATA SOURCES

Published research and education articles, on-line journals, recent texts, and references from pertinent articles.

CONCLUSION

Most melanomas are diagnosed at early localized stages when surgery alone can be curative. For patients diagnosed with metastatic disease, treatment options have been limited and generally considered ineffective. Recent developments in tumor genetics and a greater understanding of the role of the immune system in cancer have translated to better treatments.

IMPLICATIONS FOR NURSING PRACTICE

Nurses play a key role in ensuring that patients with melanoma understand their diagnosis, treatment recommendations (including supportive care, palliative chemotherapy, immunotherapies), and participation in clinical trials.

Anti-tumor effect of adipose tissue derived-mesenchymal stem cells expressing interferon-β and treatment with cisplatin in a xenograft mouse model for canine melanoma

Adipose tissue-derived mesenchymal stem cells (AT-MSCs) are attractive cell-therapy vehicles for the delivery of anti-tumor molecules into the tumor microenvironment. The innate tropism of AT-MSCs for tumors has important implications for effective cellular delivery of anti-tumor molecules, including cytokines, interferon, and pro-drugs. The present study was designed to determine the possibility that the combination of stem cell-based gene therapy with low-dose cisplatin would improve therapeutic efficacy against canine melanoma. The IFN-β transduced canine AT-MSCs (cAT-MSC-IFN-β) inhibited the growth of LMeC canine melanoma cells in direct and indirect in vitro co-culture systems. In animal experiments using BALB/c nude mouse xenografts, which developed by injecting LMeC cells, the combination treatment of cAT-MSC-IFN-β and low-dose cisplatin significantly reduced tumor volume compared with the other treatment groups. Fluorescent microscopic analysis with a TUNEL (terminal deoxynucleotidyl transferase-mediated nick-end labeling) assay of tumor section provided evidence for homing of cAT-MSC-IFN-β to the tumor site and revealed that the combination treatment of cAT-MSC-IFN-β with low-dose cisplatin induced high levels of cell apoptosis. These findings may prove useful in further explorations of the application of these combined approaches to the treatment of malignant melanoma and other tumors.

A novel phosphorylated STAT3 inhibitor enhances T cell cytotoxicity against melanoma through inhibition of regulatory T cells

The activation of signal transducer and activator of transcription 3 (STAT3) has been identified as a key mediator that drives the fundamental components of melanoma malignancy, including immune suppression in melanoma patients. Increasing evidence also suggests that regulatory T cells (Tregs) are important in suppressing anti-tumor immunity and play a dominant role in negating efficacious immunotherapy approaches. We hypothesized that WP1066, a novel inhibitor of STAT3 signaling, reverses immune suppression through the inhibition of Tregs and that this contributes to the antitumor activity of this agent against melanoma brain metastases. We found that the mean percentage of peripheral blood mononuclear cells expressing phosphorylated STAT3 (p-STAT3) was significantly elevated in samples from patients with melanoma brain metastases compared to healthy donors, 16.13 +/- 2.48% versus 4.17 +/- 1.79%. The p-STAT3 inhibitor WP1066 enhanced CD3+ (which contained Tregs) but not CD8+ T cell cytotoxicity against human A375 melanoma cells, indicating that this p-STAT3 blockade agent did not directly activate CD8+ T cells. Furthermore, the p-STAT3 inhibitor did not enhance the cytotoxicity of CD3+CD25- T cells (from which Tregs were excluded), indicating that the enhanced cytotoxicity of WP1066 is secondary to its inhibition of Tregs. This was confirmed by demonstrating that WP1066 inhibited FoxP3+ Treg induction in a dose-dependent manner. Moreover, CD3+ T cells exhibited markedly enhanced levels of phosphorylated ZAP-70, a critical proximal signal in T cell activation, after exposure to WP1066. Similar effects were not observed in Treg-depleted CD3+CD25- T cell populations, confirming that the T cell activation by WP compounds is secondary to their inhibition of the Tregs. These results suggest that WP1066 enhances T cell cytotoxicity against melanoma through inhibition of Tregs.

Obtaining routine blood cultures during interleukin-2-containing therapy is unnecessary

PURPOSE

To evaluate the usefulness of routine blood cultures in patients who develop temperatures of 38.5 degrees C or higher while treated with interleukin-2 (IL-2).

METHODS

Retrospective chart review study. Charts of patients treated with high-dose IL-2 or biochemotherapy for metastatic melanoma were reviewed at the University of Louisville from 2005 to 2007. The study objective was to estimate the frequency of true and false positive blood cultures.

RESULTS

A total of 205 blood cultures in 46 patients (27 male, 19 female) were reviewed. The average age was 53 years (25-71 years). The patients had an average of 3 cycles of therapy. The mean temperature of the febrile episodes was 38.7 degrees C. The mean absolute neutrophil count was 5.1 K/microL. Of these 205 febrile episodes, only 1 blood culture was true positive. The patient had methicillin sensitive staphylococcus aureus bacteremia. There were 5 false positive blood cultures. Four hundred thirty-four further febrile episodes were documented without blood cultures drawn. None of these patients were found to be infected. The yield of true positive blood cultures in this setting was 0.5% (0%-3%, CI). There was, however, a higher number of false positive blood cultures, 2.4% (0.5%-4.5%, CI).

CONCLUSIONS

Blood cultures during IL-2 containing therapy are very inefficient to differentiate between infections versus IL-2-related fever.

Biochemotherapy for the treatment of metastatic malignant melanoma: a systematic review

BACKGROUND

The incidence of malignant melanoma has increased in recent years. Current therapies for metastatic melanoma include chemotherapy and a variety of immunotherapeutic choices. With no established standard treatment option, the evaluation of biochemotherapy is warranted.

METHODS

A systematic review of the literature was conducted to locate randomized controlled trials, meta-analyses, systematic reviews, and evidence-based practice guidelines published up to April 2007.

RESULTS

Nine eligible randomized controlled trials were identified, including six comparing chemotherapy alone to biochemotherapy (chemotherapy combined with interleukin-2 and interferon). Response rates were significantly higher with biochemotherapy in only two trials, although when data were pooled, biochemotherapy was superior to chemotherapy on response (relative risk, 1.52; 95% confidence interval, 1.24-1.87; p<0.0001) but did not delay time to progression (Hazard ratio, 0.80; 95% confidence interval, 0.63-1.01; p=0.06). Biochemotherapy was not associated with a statistically significant survival benefit in any of the individual trials or in a pooled analysis (Hazard ratio, 0.95; 95% confidence interval, 0.78-1.17; p=0.64). Biochemotherapy is a toxic therapy, and patients are likely to experience serious hematologic, gastrointestinal, cutaneous, and constitutional toxicities, although when conducted in the correct setting, grade 3 and 4 effects appear to be manageable, and treatment-related death can be minimized.

CONCLUSION

The results of available studies are inconsistent with regard to benefit (response, time-to-progression, and survival) and show consistently high toxicity rates. Therefore, biochemotherapy is not recommended for the treatment of metastatic malignant melanoma in adults.