Treatments for metastatic melanoma: synthesis of evidence from randomized trials

Metastatic tumor dormancy in cutaneous melanoma: does surgery induce escape?

According to the concept of tumor dormancy, tumor cells may exist as single cells or microscopic clusters of cells that are clinically undetectable, but remain viable and have the potential for malignant outgrowth. At metastatic sites, escape from tumor dormancy under more favorable local microenvironmental conditions or through other, yet undefined stimuli, may account for distant recurrence after supposed "cure" following surgical treatment of the primary tumor. The vast majority of evidence to date in support of the concept of tumor dormancy originates from animal studies; however, extensive epidemiologic data from breast cancer strongly suggests that this process does occur in human disease. In this review, we aim to demonstrate that metastatic tumor dormancy does exist in cutaneous melanoma based on evidence from mouse models and clinical observations of late recurrence and occult transmission by organ transplantation. Experimental data underscores the critical role of impaired angiogenesis and immune regulation as major mechanisms for maintenance of tumor dormancy. Finally, we examine evidence for the role of surgery in promoting escape from tumor dormancy at metastatic sites in cutaneous melanoma.

Targeted Therapy Database (TTD): a model to match patient's molecular profile with current knowledge on cancer biology

Background

The efficacy of current anticancer treatments is far from satisfactory and many patients still die of their disease. A general agreement exists on the urgency of developing molecularly targeted therapies, although their implementation in the clinical setting is in its infancy. In fact, despite the wealth of preclinical studies addressing these issues, the difficulty of testing each targeted therapy hypothesis in the clinical arena represents an intrinsic obstacle. As a consequence, we are witnessing a paradoxical situation where most hypotheses about the molecular and cellular biology of cancer remain clinically untested and therefore do not translate into a therapeutic benefit for patients.

Objective

To present a computational method aimed to comprehensively exploit the scientific knowledge in order to foster the development of personalized cancer treatment by matching the patient's molecular profile with the available evidence on targeted therapy.

Methods

To this aim we focused on melanoma, an increasingly diagnosed malignancy for which the need for novel therapeutic approaches is paradigmatic since no effective treatment is available in the advanced setting. Relevant data were manually extracted from peer-reviewed full-text original articles describing any type of anti-melanoma targeted therapy tested in any type of experimental or clinical model. To this purpose, Medline, Embase, Cancerlit and the Cochrane databases were searched.

Results and Conclusions

We created a manually annotated database (Targeted Therapy Database, TTD) where the relevant data are gathered in a formal representation that can be computationally analyzed. Dedicated algorithms were set up for the identification of the prevalent therapeutic hypotheses based on the available evidence and for ranking treatments based on the molecular profile of individual patients. In this essay we describe the principles and computational algorithms of an original method developed to fully exploit the available knowledge on cancer biology with the ultimate goal of fruitfully driving both preclinical and clinical research on anticancer targeted therapy. In the light of its theoretical nature, the prediction performance of this model must be validated before it can be implemented in the clinical setting.

Long-term survival in patients with metastatic melanoma treated with DTIC or temozolomide

BACKGROUND

Patients with metastatic melanoma typically have a poor outcome; however, a small proportion of patients achieve long-term survival (LTS). It is unclear how often LTS is related to sensitivity to chemotherapy.

METHODS

All patients with metastatic melanoma treated with either dacarbazine (DTIC) or temozolomide (TMZ) at the British Columbia Cancer Agency (BCCA) from January 1, 1988 to February 1, 2006 were identified through the BCCA pharmacy electronic database, which was then linked to the surveillance and outcomes unit to identify patients with LTS, defined as survival > or =18 months following chemotherapy.

RESULTS

In total, 397 patients were treated with either DTIC (n = 349) or TMZ (n = 48) and 43 patients (10.8%) were identified with LTS. Two additional patients with LTS were added prior to 1988 for a total of 45 patients. The 5-year overall and progression-free survival rates for patients with LTS were 33% and 16%, respectively. In total, 16% had a complete response (CR) to chemotherapy, which was the only factor identified that correlated with survival in the multivariate analysis. However, most patients with LTS had an incomplete response to chemotherapy.

CONCLUSIONS

LTS occurs in select patients who achieve a CR to chemotherapy. However, this occurs in only a minority of patients and, in most cases, the longer survival is likely the result of indolent disease biology or host factors.

Novel immunotherapies as potential therapeutic partners for traditional or targeted agents: cytotoxic T-lymphocyte antigen-4 blockade in advanced melanoma

The successful management of advanced melanoma remains an unmet need because of a resolutely poor prognosis and therapeutic options with limited effectiveness. Dacarbazine and fotemustine are the only approved chemotherapeutic agents for advanced melanoma, yet neither alone or in combination regimens has been shown to extend survival in randomized clinical trials. The only agent to be approved for advanced melanoma in the US in more than 30 years is high-dose bolus interleukin-2, but its use is associated with high toxicity and cost, and it has also failed to show a survival benefit. Our expanding knowledge of the complex factors and pathways regulating immune function has led to the advent of novel immunotherapeutic agents. Among these are ipilimumab and tremelimumab - fully human, monoclonal antibodies directed against cytotoxic T-lymphocyte antigen-4 (CTLA-4). The pivotal role of CTLA-4 in regulating T-cell function is established, and a series of preclinical studies provided proof-of-concept evidence of the antitumor activity of anti-CLTA-4 antibodies in combination with vaccines or chemotherapy. Subsequently, anti-CTLA-4 antibodies have shown encouraging results in clinical trials in advanced melanoma. Recent progress in the understanding of melanoma genetics and tumorigenesis has led to potential new therapeutic targets. Molecular targeted agents that inhibit the proliferation and survival of metastatic melanoma cells offer potential partners for anti-CTLA-4 antibodies in combined modality regimens. Novel combinations are reviewed in the context of creating an immunosupportive environment in the host.

Cost-effectiveness analysis of FDG PET-CT in the management of pulmonary metastases from malignant melanoma

OBJECTIVES

Most guidelines consider FDG PET-CT to detect occult extra-pulmonary disease prior to lung metastasectomy. A cost-effectiveness analysis, using a Markov model over a 10 year period, was performed to compare two different surveillance programs, either PET-CT or whole-body CT, in patients with suspected pulmonary metastasised melanoma.

METHODS

Data from published studies provided probabilities for the model. Complication and care costs were obtained from standardised administrative databases from 19 hospitals identified by DRG codes (reported in 2009 Euros). For the cost calculation of PET-CT we performed a microcosting analysis. All costs and benefits were yearly discounted at respectively 3% and 1.5%. Outcomes included life-months gained (LMG) and the number of futile surgeries avoided. Cost-effectiveness ratios were in Euros per LMG. Univariate and probabilistic sensitivity analyses addressed uncertainty in all model parameters.

RESULTS

The PET-CT strategy provided 86.29 LMG (95% CI: 81.50-90.88 LMG) at a discounted cost of euro3,974 (95% CI: euro1,339-12,303), while the conventional strategy provided 86.08 LMG (95% CI: 81.37-90.68 LMG) at a discounted cost of euro5,022 (95% CI: euro1,378-16,018). This PET-CT strategy resulted in a net saving of euro1,048 with a gain of 0.2 LMG. Based on PET-CT findings, 20% of futile surgeries could be avoided.

CONCLUSION

Integrating PET-CT in the management of patients with high risk MM appears to be less costly and more accurate by avoiding futile thoracotomies in one of five patients as well as by providing a small survival benefit at 10 years.

Interferon alpha adjuvant therapy in patients with high-risk melanoma: a systematic review and meta-analysis

BACKGROUND

Based on previous meta-analyses of randomized controlled trials (RCTs), the use of interferon alpha (IFN-alpha) in the adjuvant setting improves disease-free survival (DFS) in patients with high-risk cutaneous melanoma. However, RCTs have yielded conflicting data on the effect of IFN-alpha on overall survival (OS).

METHODS

We conducted a systematic review and meta-analysis to examine the effect of IFN-alpha on DFS and OS in patients with high-risk cutaneous melanoma. The systematic review was performed by searching MEDLINE, EMBASE, Cancerlit, Cochrane, ISI Web of Science, and ASCO databases. The meta-analysis was performed using time-to-event data from which hazard ratios (HRs) and 95% confidence intervals (CIs) of DFS and OS were estimated. Subgroup and meta-regression analyses to investigate the effect of dose and treatment duration were also performed. Statistical tests were two-sided.

RESULTS

The meta-analysis included 14 RCTs, published between 1990 and 2008, and involved 8122 patients, of which 4362 patients were allocated to the IFN-alpha arm. IFN-alpha alone was compared with observation in 12 of the 14 trials, and 17 comparisons (IFN-alpha vs comparator) were generated in total. IFN-alpha treatment was associated with a statistically significant improvement in DFS in 10 of the 17 comparisons (HR for disease recurrence = 0.82, 95% CI = 0.77 to 0.87; P < .001) and improved OS in four of the 14 comparisons (HR for death = 0.89, 95% CI = 0.83 to 0.96; P = .002). No between-study heterogeneity in either DFS or OS was observed. No optimal IFN-alpha dose and/or treatment duration or a subset of patients more responsive to adjuvant therapy was identified using subgroup analysis and meta-regression.

CONCLUSION

In patients with high-risk cutaneous melanoma, IFN-alpha adjuvant treatment showed statistically significant improvement in both DFS and OS.

A phase II study of oxaliplatin, docetaxel, and GM-CSF in patients with previously treated advanced melanoma

PURPOSE

Although much focus has been placed on immunotherapy for melanoma, further development of chemotherapy approaches is needed. Melanoma is responsive to platinum compounds and taxanes, but there is limited experience with combinations of these agents. Oxaliplatin has been reported to have detectable activity in melanoma, and a phase I study has identified a tolerable dose and schedule of oxaliplatin in combination with docetaxel and hematopoietic growth factor support. GM-CSF has a theoretical advantage of immune potentiation. These considerations supported the study of oxaliplatin, docetaxel, and GM-CSF in patients with advanced melanoma.

METHODS

Eligibility included adequate organ function, PS<or=2, at most one prior chemotherapy and one prior immunotherapy, no prior treatment with oxaliplatin or taxanes and no chremophor allergy. After premedication, docetaxel was administered day 1 at 75 mg/m2, then oxaliplatin on day 2 at 85 mg/m2. GM-CSF (250 mcg/m2) was administered s.c. days 3-12. Cycles were 21 days in length, and disease reevaluation was performed every two cycles by RECIST criteria.

RESULTS

Nineteen patients received at least one cycle, eight with one prior systemic therapy, five with two prior systemic therapies. Five patients did not complete two cycles and were not formally evaluable for response. Five patients had stable disease (SD), including one who failed two prior therapies and went on to receive ten cycles. The remaining nine patients displayed progressive disease (PD) after two cycles. Notable toxicities included seven cases (37%) of grade III/IV neutropenia and two (11%) hypersensitivity reactions.

CONCLUSIONS

This combination of oxaliplatin, docetaxel, and GM-CSF has limited clinical activity in previously treated patients with advanced melanoma. Exploration in treatment-naïve patients may still be warranted.

Evidence of gamma-tocotrienol as an apoptosis-inducing, invasion-suppressing, and chemotherapy drug-sensitizing agent in human melanoma cells

To date, the most effective cure for metastatic melanoma remains the surgical resection of the primary tumor. Recently, tocotrienol-rich-fraction has shown antiproliferative effect on cancer cells. To elucidate this anticancer property in malignant melanoma, this study aimed, first, to identify the most potent isomer for eliminating melanoma cells and second to decipher the molecular pathway responsible for its activity. Results showed that the inhibitory effect of gamma-tocotrienol was most potent, which resulted in induction of apoptosis as evidenced by activation of procaspases and the accumulation of sub-G1 cell population. Examination of the prosurvival genes revealed that the gamma-tocotrienol-induced cell death was associated with suppression of NF-kappaB, EGF-R, and Id family proteins. Meanwhile, gamma-tocotrienol treatment also resulted in induction of JNK signaling pathway, and inhibition of JNK activity by selective inhibitor was able to partially block the effect of gamma-tocotrienol. Interestingly, gamma-tocotrienol treatment led to suppression of mesenchymal markers and the restoration of E-cadherin and gamma-catenin expression, which was associated with suppression of cell invasion capability. Furthermore, synergistic effect was observed when cells were cotreated with gamma-tocotrienol and chemotherapy drugs. Together, our results demonstrated for the first time the anti-invasion and chemonsensitization effect of gamma-tocotrienol against human malignant melanoma cells.

Targeting Akt3 signaling in malignant melanoma using isoselenocyanates

PURPOSE

Melanoma is the most invasive and deadly form of skin cancer. Few agents are available for treating advanced disease to enable long-term patient survival, which is driving the search for new compounds inhibiting deregulated pathways causing melanoma. Akt3 is an important target in melanomas because its activity is increased in approximately 70% of tumors, decreasing apoptosis in order to promote tumorigenesis.

EXPERIMENTAL DESIGN

Because naturally occurring products can be effective anticancer agents, a library was screened to identify Akt3 pathway inhibitors. Isothiocyanates were identified as candidates, but low potency requiring high concentrations for therapeutic efficacy made them unsuitable. Therefore, more potent analogs called isoselenocyanates were created using the isothiocyanate backbone but increasing the alkyl chain length and replacing sulfur with selenium. Efficacy was measured on cultured cells and tumors by quantifying proliferation, apoptosis, toxicity, and Akt3 pathway inhibition.

RESULTS

Isoselenocyanates significantly decreased Akt3 signaling in cultured melanoma cells and tumors. Compounds having 4 to 6 carbon alkyl side chains with selenium substituted for sulfur, called ISC-4 and ISC-6, respectively, decreased tumor development by approximately 60% compared with the corresponding isothiocyanates, which had no effect. No changes in animal body weight or in blood parameters indicative of liver-, kidney-, or cardiac-related toxicity were observed with isoselenocyanates. Mechanistically, isoselenocyanates ISC-4 and ISC-6 decreased melanoma tumorigenesis by causing an approximately 3-fold increase in apoptosis.

CONCLUSIONS

Synthetic isoselenocyanates are therapeutically effective for inhibiting melanoma tumor development by targeting Akt3 signaling to increase apoptosis in melanoma cells with negligible associated systemic toxicity.

Potential for cripto-1 in defining stem cell-like characteristics in human malignant melanoma

The diagnosis of melanoma is becoming ever more frequent. Although surgical excision of early lesions is associated with relatively significant high cure rates, treatment modalities are largely unsuccessful for advanced disease. Characteristics such as cellular heterogeneity and plasticity, expression of certain molecules such as the multidrug resistance protein-1 (MDR1) or the aberrant expression of embryonic signaling molecules and morphogens like Nodal, important for self renewal and pluripotency, suggest that a stem cell-like population may reside in aggressive melanomas. This perspective focuses on preliminary findings obtained in our laboratory which indicate that the expression of the Nodal coreceptor, Cripto-1, in a subset of malignant melanoma cells may be exploited to identify possible melanoma stem cells (MSC). In fact, the use of anti-Cripto-1 antibodies to cell sort Cripto-1-positive cells in the metastatic melanoma cell line C8161 has identified a slow growing, sphere forming subpopulation that expresses increased levels of Oct4, Nanog and MDR1. If current in vivo studies confirm the self renewal and tumorigenic characteristics of these cells, the expression of Cripto-1 may represent a useful marker to identify cancer stem cells in melanoma, and possibly other aggressive tumors as well.