Next generation of immunotherapy for melanoma

A new understanding in the epidemiology of melanoma

The incidence of melanoma is continuing to increase worldwide. UV exposure is a known risk factor for melanoma. Geographic location is known to influence UV exposure and the distribution of the incidence of melanoma. Furthermore, epidemiologic data suggest that gender and genetics may influence the distribution of melanoma on the body surface and histopathologic characteristics of the lesion. This article describes what is known about the impact of gender, ethnicity and geography on the progression of melanoma. Advanced-stage cutaneous melanoma has a median survival time of less than 1 year. Surgical removal, radiotherapy, chemotherapy, targeted therapies and a variety of immunotherapies have been utilized in the treatment of melanoma. Current treatment strategies and the results of recent clinical trials are also discussed in this article.

Dendritic cell vaccination in combination with anti-CD25 monoclonal antibody treatment: a phase I/II study in metastatic melanoma patients

PURPOSE

The success of cancer immunotherapy depends on the balance between effector T cells and suppressive immune regulatory mechanisms within the tumor microenvironment. In this study we investigated whether transient monoclonal antibody-mediated depletion of CD25(high) regulatory T cells (Treg) is capable of enhancing the immunostimulatory efficacy of dendritic cell vaccines.

EXPERIMENTAL DESIGN

Thirty HLA-A2.1(+) metastatic melanoma patients were vaccinated with mature dendritic cells pulsed with tumor peptide and keyhole limpet hemocyanin (KLH). Half of the patients were pretreated with daclizumab, a humanized antibody against the interleukin-2 (IL-2) receptor α-chain (CD25), either four or eight days before dendritic cell vaccinations. Clinical and immunologic parameters were determined.

RESULTS

Daclizumab efficiently depleted all CD25(high) immune cells, including CD4(+)FoxP3(+)CD25(high) cells, from the peripheral blood within four days of administration. Thirty days after administration, daclizumab was cleared from the circulation and all CD25(+) cells reappeared. The presence of daclizumab during dendritic cell vaccinations prevented the induction of specific antibodies in vivo but not the presence of antigen-specific T cells. Daclizumab, however, did prevent these CD25(+) T cells from acquiring effector functions. Consequently, significantly less patients pretreated with daclizumab developed functional, vaccine-specific effector T cells and antibodies compared with controls. Daclizumab pretreatment had no significant effect on progression-free survival compared with the control group.

CONCLUSIONS

Although daclizumab depleted the CD4(+)FoxP3(+)CD25(high) Tregs from the peripheral circulation, it did not enhance the efficacy of the dendritic cell vaccine. Residual daclizumab functionally suppressed de novo induced CD25(+) effector cells during dendritic cell vaccinations. Our results indicate that for immunotherapeutic benefit of transient Treg depletion, timing and dosing as well as Treg specificity are extremely important.

Potential target antigens for a universal vaccine in epithelial ovarian cancer

The prognosis of epithelial ovarian cancer (EOC), the primary cause of death from gynaecological malignancies, has only modestly improved over the last decades. Immunotherapeutic treatment using a cocktail of antigens has been proposed as a "universal" vaccine strategy. We determined the expression of tumor antigens in the context of MHC class I expression in 270 primary tumor samples using tissue microarray. Expression of tumor antigens p53, SP17, survivin, WT1, and NY-ESO-1 was observed in 120 (48.0%), 173 (68.9%), 208 (90.0%), 129 (56.3%), and 27 (11.0%) of 270 tumor specimens, respectively. In 93.2% of EOC, at least one of the investigated tumor antigens was (over)expressed. Expression of MHC class I was observed in 78.1% of EOC. In 3 out 4 primary tumors, (over)expression of a tumor antigen combined with MHC class I was observed. These results indicate that a multiepitope vaccine, comprising these antigens, could serve as a universal therapeutic vaccine for the vast majority of ovarian cancer patients.

Inhibiting the inhibitors: evaluating agents targeting cancer immunosuppression

IMPORTANCE OF THE FIELD

Immunotherapy of cancer has not improved disease-free or overall patient survival. The lack of concordance between immunological and clinical responses in cancer immunotherapy trials is thought to result from the pervasive presence of tumor-driven immune suppression that allows tumor to escape and that has not been adequately targeted by current therapies.

AREAS COVERED IN THIS REVIEW

Because multiple mechanisms of tumor induced suppression have been identified and shown to contribute to tumor escape, the opportunity arises to interfere with these mechanisms. A range of known tumor-derived inhibitors can now be blocked or neutralized by biologic or metabolic agents. Used alone or in combination with each other or with conventional cancer therapies, these agents offer novel therapeutic strategies for the control of tumor escape.

WHAT THE READER WILL GAIN

This review deals with currently available inhibitors for counteracting tumor immune escape. The restoration of effective anti-tumor immunity in patients with cancer will require new approaches aiming at: i) protection of immune cells from adverse effects of myeloid-derived suppressor cells, regulatory T cells or inhibitory factors thus enhancing effector functions; and ii) prolonging survival of central memory T cells, thus ensuring long-term protection.

TAKE HOME MESSAGE

Inhibitors of mechanisms responsible for tumor escape could restore anti-tumor immune responses in patients with cancer.

Immunotherapy of melanoma by GPI-anchored IL-21 tumour vaccine involves down-regulating regulatory T cells in mouse model

In this study, we developed a tumour cell vaccine expressing a glycosylphosphatidylinositol (GPI)-anchored IL-21 to test the effect of immunotherapy of melanoma in mouse model. The results indicated that the tumour vaccine was functional, exhibiting delayed tumour growth and prolonging longevity of tumour bearing mice. The immunotherapeutic effect was associated with decreasing the numbers of CD4(+) CD25(+) Foxp3(+) Treg (Tregs) cells, increasing IFN-γ level and promoting lymphocyte-infiltration in tumour tissues. Overall, our data demonstrate that the GPI-anchored IL-21 tumour vaccine regulates immune responses at least in part by down-regulating Tregs and reveals enhanced efficacy of tumour vaccine therapy of melanoma.

Fine analysis of spontaneous MAGE-C1/CT7-specific immunity in melanoma patients

Cancer/testis (CT) antigens represent prime candidates for immunotherapy in cancer patients, because their expression is restricted to cancer cells and germ cells of the testis. MAGE-C1/CT7 is a CT antigen that is highly expressed in several types of cancers. Spontaneous occurrence of CT7-specific antibodies was previously detected by SEREX screen in a melanoma patient. However, naturally occurring CT7-specific T-cell responses have thus far not been detected. Peripheral blood mononuclear cells (PBMCs) from 26 metastatic melanoma patients expressing CT7 in their tumor lesions (CT7(+)) were analyzed for CT7-specific T-cell responses using overlapping peptides. CT7-specific CD4(+) T-cell responses were detected in three patients (11.5%). These CT7-specific CD4(+) T-cell responses were detectable in melanoma patients' PBMCs exclusively from preexisting CD45RA(-) memory CD4(+) T-cell pool. Additional CT7-specific memory CD4(+) T-cell responses were detected in CT7(+) melanoma patients after depletion of CD4(+)CD25high Treg cells showing that Treg cells impact on CT7-specific CD4(+) T cells in melanoma patients. CT7-specific CD4(+) T-cell clones were generated and used to define minimal epitopes, restriction elements, and confirm the recognition of naturally processed antigen. Surprisingly, these clones were able to secrete perforin and exert cytotoxicity. This study shows that CT7 can induce specific cellular immunity in melanoma patients. Based on these findings, CT7 will be further explored as a potential vaccine for melanoma immunotherapy.

Interferon-lambda as a potential therapeutic agent in cancer treatment

The discovery that type I interferon (IFN-alpha/beta) inhibited tumor cell growth was welcomed initially with great excitement as it rapidly became a U.S. Food and Drug Administration-approved drug to treat several forms of cancer. In time, this enthusiasm diminished as severe toxicity associated with IFN-alpha administration, resistance to the therapy, or less than optimal responses became evident in cancer patients, thus restricting its clinical use and reducing its potential as an anticancer drug. The recent discovery of a third type of IFN [IFN-lambda/interleukin (IL)-29/IL-28], which shares the same biological properties of type I IFNs, opens the door for evaluating the therapeutic potential of IFN-lambda as it uses a distinct receptor complex whose expression, unlike type I IFN receptors, is restricted to cells of specific lineage. It is unclear whether the mechanism by which type III IFNs restrict tumor cell proliferation is different or the same from the one utilized by type I IFN. Nevertheless, accumulating evidence as described in this review suggests that, in contrast to IFN-alpha therapy, IFN-lambda therapy could be less toxic and suitable for certain types of malignancies as not all cells are responsive to this cytokine.

Interleukin-28 and interleukin-29: novel regulators of skin biology

The skin forms an essential barrier between the inside of an organism and the environment. In addition to its function in insulation, temperature regulation, and sensation, it protects the body against physical trauma, pathogens, UV radiation, and excessive water loss. Many processes necessary for maintaining the skin integrity, including antimicrobial/antiviral defense, wound healing, and removal of tumors, are regulated by cytokines. Accumulating results lead us to assume that interleukin (IL)-28 and IL-29, 2 novel members of the IL-10-interferon cytokine family, are important regulators of some of these processes. In the skin, IL-28 and IL-29 can be produced by virus-infected cells, maturing dendritic cells (DCs), and regulatory T-cells, and they mainly influence keratinocytes and melanocytes. In keratinocytes, IL-28 and IL-29 induce growth inhibition. Simultaneously, these cytokines increase the cellular synthesis of proteins that directly hinder virus replication and enhance the readiness to present viral antigens to immune cells. Further, IL-28 and IL-29 upregulate expression of viral and microbial sensing cellular receptors, including toll-like receptor (TLR)3, TLR2, and melanoma differentiation associated gene 5, and strengthen the cellular response to these receptors' ligands. Thereby, in the noninfected skin IL-28 and IL-29 enhance the capacity of keratinocytes to react to viral and microbial products and at least indirectly upregulate their inflammatory potential and innate immunity. IL-28 and IL-29 can act synergistically with other mediators secreted during DC maturation (eg, IL-20). In summary, IL-28/IL-29 may play an important role in the skin in the clearance of viral and microbial infections and in the removal of tumors.

IL-28A, IL-28B, and IL-29: promising cytokines with type I interferon-like properties

IL-28A, IL-28B and IL-29 (also designated type III interferons) constitute a new subfamily within the IL-10-interferon family. They are produced by virtually any nucleated cell type, particularly dendritic cells, following viral infection or activation with bacterial components, and mediate their effects via the IL-28R1/IL-10R2 receptor complex. Although IL-28/IL-29 are closer to the IL-10-related cytokines in terms of gene structure, protein structure, and receptor usage, they display type I interferon-like anti-viral and cytostatic activities. Unlike type I interferons, the target cell populations of IL-28/IL-29 are restricted and mainly include epithelial cells and hepatocytes. These properties suggest that IL-28/IL-29 are potential therapeutic alternatives to type I interferons in terms of viral infections and tumors. This review describes the current knowledge about these cytokines.

CpG oligodeoxynucleotides as TLR9 agonists: therapeutic applications in cancer

Toll-like receptors (TLRs) are part of the innate immune system, and they belong to the pattern recognition receptors (PRR) family. The PRR family is designed to recognize and bind conserved pathogen-associated molecular patterns, which are not generated by the host and are restricted and essential to micro-organisms. TLR9, which recognizes unmethylated CpG (cytosine guanosine dinucleotide), is a very promising target for therapeutic activation. Stimulation of TLR9 activates human plasmacytoid dendritic cells and B cells, and results in potent T helper-1 (T(h)1)-type immune responses and antitumor responses in mouse tumor models and in patients. Several pharmaceutical companies, such as Pfizer, Idera, and Dynavax, are developing CpG oligodeoxynucleotides (ODNs) for the treatment of cancer, along with other conditions, such as infections and allergy. CpG ODNs have shown promising results as vaccine adjuvants and in combination with cancer immunotherapy. Several TLR9 agonists are being developed and have entered clinical trials to evaluate their safety and efficacy for the treatment of several hematopoietic and solid tumors. In this review, we discuss the use of CpG ODNs in several phase I and II clinical trials for the treatment of NHL, renal cell carcinoma, melanoma, and non-small cell lung cancer, either alone or in combination with other agents.

Differential mechanisms of memory CD8 T cell maintenance by individual myeloid cell types

This study tested the hypothesis that individual myeloid subsets have a differential ability to maintain memory CD8 T cells via IL-15. Although DCs support IL-15-mediated homeostasis of memory CD8 T cells in vivo, whether various DC subsets and other myeloid cells similarly mediate homeostasis is unknown. Therefore, we studied the ability of different myeloid cells to maintain memory CD8 T cells in vitro. Using an in vitro cocoulture system that recapitulated known roles of DCs and IL-15 on memory CD8 T cells, all in vitro-derived or ex vivo-isolated DCs maintained CD8 T cells better than rIL-15 alone, and FLT-3L-DCs are the most efficient compared with GM-DCs, BM-derived macrophages, or freshly isolated DCs. Although FLT-3L-DCs were the least effective at inducing CD8 T cell proliferation, FLT-3L-DCs promoted better CD8 T cell survival and increased Bcl-2 and MCL-2 expression in CD8 T cells. T cell maintenance correlated only partially with DC expression of IL-15Ralpha and IL-15, suggesting that DCs provided additional support signals. Indeed, in the absence of IL-15 signals, CD70/CD27 further supported CD8 T cell maintenance. IFN-alpha enhanced CD70 expression by DCs, resulting in increased proliferation of CD8 T cells. Overall, this study supports our hypothesis by demonstrating that specific DC subtypes had a greater capacity to support memory CD8 T cell maintenance and did so through different mechanisms. Furthermore, this study shows that IL-15 trans-presentation can work in conjunction with other signals, such as CD70/CD27 interactions, to mediate CD8 T cell homeostasis efficiently.

Continuous systemic corticosteroids do not affect the ongoing regression of metastatic melanoma for more than two years following ipilimumab therapy

Malignant melanoma is an aggressive skin cancer with no effective therapies currently approved for advanced disease. In the case presented, a 55-year-old female patient diagnosed with widespread disease from amelanotic desmoplastic melanoma was treated with 10 mg/kg ipilimumab as part of a phase II clinical trial (CA184-008). Prior to ipilimumab, three chemotherapeutic regimens had failed. Ipilimumab acts as a T-cell potentiator via blockade of cytotoxic T-lymphocyte antigen-4, a negative regulator of T-cell activation. Response to ipilimumab treatment was rapid, with a substantial drop in tumor volume within 12 weeks of treatment initiation. Based on the appearance of a new subcutaneous lesion, reinduction with ipilimumab was performed at Week 30. Following reinduction, the appearance of another small new lesion made the patient ineligible, as per protocol, for further dosing despite stabilization of her remaining lesions. Ipilimumab-associated immune-related adverse events were manageable with the use of treatment guidelines. It is of remarkable immunotherapeutic importance that no new lesions emerged and gradual tumor regression is still ongoing more than 2 years following the last dose of ipilimumab, despite daily administration of systemic corticosteroids to manage drug-induced AEs. The ongoing clinical response is maintained without any further antineoplastic treatment.

Gene-expression profiling in vaccine therapy and immunotherapy for cancer

The identification of tumor antigens recognized by T cells led to the design of therapeutic strategies aimed at eliciting adaptive immune responses. The last decade of experience has shown that, although active immunization can induce enhancement of anticancer T-cell precursors (easily detectable in standard assays), most often they are unable to induce tumor regression and, consequently, have scarcely any impact on overall survival. Moreover, in the few occasions when tumor rejection occurs, the mechanisms determining this phenomenon remain poorly understood, and data derived from in vivo human observations are rare. The advent of high-throughput gene-expression analysis (microarrays) has cast new light on unrecognized mechanisms that are now deemed to be central for the development of efficient immune-mediated tumor rejection. The aim of this article is to review the data on the molecular signature associated with this process. We believe that the description of how the mechanism of immune-mediated tissue destruction occurs would contribute to our understanding of why it happens, thereby allowing us to develop more effective immune therapeutic strategies.

A new era in anticancer peptide vaccines

The use of synthetic peptides as vaccines aimed at the induction of therapeutic CD8-positive T-cell responses against tumor cells initially experienced great enthusiasm, mostly because of advances in vaccine technology, including design, synthesis, and delivery. However, despite impressive results in animal models, the application of such vaccines in humans has met with only limited success. The therapeutic activity of vaccine-stimulated, tumor-specific, CD8-positive T cells can be hampered through the physical burden of the tumor, tolerance mechanisms, and local factors within the tumor microenvironment. Recently, accumulating evidence has suggested that combining a peptide-based therapeutic vaccination with conventional chemotherapy can uncover the full potential of the antitumor immune response, increasing the success of immunotherapy. In addition, therapeutic vaccination in the preventive setting has been extremely effective in eliciting antitumor responses in preclinical tumor models and has demonstrated good promise clinically in patients with minimal residual disease. The rationale behind preventive vaccination is that patients with minimal tumor burden still have a fully competent immune system capable of developing robust antitumor responses. Finally, therapeutic CD8-positive T-cell peptide vaccines have been improved by coimmunization with T-helper epitopes expressed on long peptides.

Anti-GD3 chimeric sFv-CD28/T-cell receptor zeta designer T cells for treatment of metastatic melanoma and other neuroectodermal tumors

PURPOSE

The aims of this study are to compare antitumor activities of two generations of GD3-specific chimeric antigen receptors (CAR) in human primary T lymphocytes in vitro and to evaluate the antitumor efficacy of using a combination of systemic infusion of interleukin-2 (IL2) and designer T cells to eradicate subcutaneous established GD3+ melanoma in nude mice.

EXPERIMENTAL DESIGN

Antitumor activities were compared for two generations of designer T cells, the progenitor first-generation with immunoglobulin T-cell receptor (TCR) with Signal 1 and the second-generation designer T cells with Signal 1+2. Osmotic IL2 pumps were used to deliver the maximum tolerated dose of IL2 to enhance the antitumor effects of designer T cells on subcutaneous established melanoma in nude mice.

RESULTS

Melanoma is associated with high expression of ganglioside GD3, which has been targeted with modest effect in antibody therapies. We previously showed that an anti-GD3 CAR (sFv-TCRzeta) will recruit T cells to target this non-T-dependent antigen, with potent killing of melanoma cells. Here, we report the addition of a CD28 costimulation domain to create a second-generation CAR, called Tandem for two signals. We show that this Tandem sFv-CD28/TCRzeta receptor on T cells confers advantages of improved cytokine secretion, cytotoxicity, proliferation, and clonal expansion on tumor contact versus the same CAR without costimulation. In an adoptive transfer model using established melanoma tumors, designer T cells with CD28 showed a 50% rate of complete remissions but only where IL2 was supplemented.

CONCLUSIONS

As a reagent for clinical development, the second-generation product is shown to have superior properties to warrant its preference for clinical designer T-cell immunotherapy for melanoma and other tumors. Systemic IL2 was required for optimal activity in an established tumor model.

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.

Phase II trial of tremelimumab (CP-675,206) in patients with advanced refractory or relapsed melanoma

PURPOSE

This phase II study assessed the antitumor activity of tremelimumab, a fully human, anti-CTL-associated antigen 4 monoclonal antibody, in patients with melanoma.

EXPERIMENTAL DESIGN

Patients with refractory/relapsed melanoma received 15 mg/kg tremelimumab every 90 days. After 4 doses, patients with tumor response or stable disease were eligible to receive < or =4 additional doses. Primary endpoint was best overall tumor response assessed by an independent endpoint review committee, and secondary endpoints included duration of response, overall survival, progression-free survival, and safety.

RESULTS

Of 251 patients enrolled, 246 (241 response-evaluable) received tremelimumab. Objective response rate was 6.6% (16 partial responses); duration of response was 8.9 to 29.8 months. Eight (50%) objective responses occurred in patients with stage IV M(1c) disease, and 11 (69%) were ongoing at last tumor assessment. Eight (3.3%) patients achieved responses in target lesions (Response Evaluation Criteria in Solid Tumors) despite progressive disease within the first cycle. All 8 survived for >20 months; 5 (63%) remained alive. Clinical benefit rate (overall response + stable disease) was 21% (16 partial responses and 35 stable disease), and median overall survival was 10.0 months. Progression-free survival at 6 months was 15%, and survival was 40.3% at 12 months and 22% at 24 months. Common treatment-related adverse events were generally mild to moderate, and grade 3/4 adverse events included diarrhea (n = 28, 11%), fatigue (n = 6, 2%), and colitis (n = 9, 4%). There were 2 (0.8%) treatment-related deaths.

CONCLUSIONS

Tremelimumab showed an objective response rate of 6.6%, with all responses being durable > or =170 days since enrollment, suggesting a potential role for tremelimumab in melanoma.

The role of toll-like receptors in host defenses and their relevance to dermatologic diseases

The family of toll-like receptors (TLRs) plays a central role in the cutaneous immune defense system. To date, different TLRs have been found on several major cell populations of the skin, such as keratinocytes, fibroblasts, antigen-presenting cells, and melanocytes. Activation of TLRs leads, via different intracellular signaling pathways, to the production of pro-inflammatory stimuli, and is considered a danger signal that should transform the skin in to the functional state of defense. However, TLRs have also been implicated in tissue homeostasis and renewal. Within the group of TLRs, two types have been identified: surface-expressed TLRs, which are predominantly active against bacterial cell wall compounds; and intracellular receptors, which preferentially recognize virus-associated pattern molecules. In addition, surface-expressed receptors trigger phagocytotic and maturation signals, while the intracellular TLRs lead to the induction of antiviral genes. Our review aims to outline the importance of TLRs in the pathogenesis of numerous skin diseases and the potential of TLR agonists as a treatment option for various skin diseases.

Modulation of T-cell activation by malignant melanoma initiating cells

Highly immunogenic cancers such as malignant melanoma are capable of inexorable tumor growth despite the presence of antitumor immunity. Thus, only a restricted minority of tumorigenic malignant cells may possess the phenotypic and functional characteristics needed to modulate tumor-directed immune activation. Here we provide evidence supporting this hypothesis. Tumorigenic ABCB5(+) malignant melanoma initiating cells (MMICs) possessed the capacity to preferentially inhibit IL-2-dependent T-cell activation and to support, in a B7.2-dependent manner, induction of CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs). Compared with melanoma bulk cell populations, ABCB5(+) MMICs displayed lower levels of MHC class I, aberrant positivity for MHC class II, and lower expression levels of the melanoma-associated antigens MART-1, ML-IAP, NY-ESO-1, and MAGE-A. Additionally, these tumorigenic ABCB5(+) subpopulations preferentially expressed the costimulatory molecules B7.2 and PD-1, both in established melanoma xenografts and in clinical tumor specimens. In immune activation assays, MMICs inhibited mitogen-dependent human peripheral blood mononuclear cell (PBMC) proliferation and IL-2 production more efficiently than ABCB5(-) melanoma cell populations. Moreover, coculture with ABCB5(+) MMICs increased the abundance of Tregs, in a B7.2 signaling-dependent manner, along with IL-10 production by mitogen-activated PBMCs. Consistent with these findings, MMICs also preferentially inhibited IL-2 production and induced IL-10 secretion by cocultured patient-derived, syngeneic PBMCs. Our findings identify novel T-cell modulatory functions of ABCB5(+) melanoma subpopulations and suggest specific roles for these MMICs in the evasion of antitumor immunity and in cancer immunotherapeutic resistance.

Melanoma-associated antigen expression in lymphangioleiomyomatosis renders tumor cells susceptible to cytotoxic T cells

The antibody HMB45 is used to diagnose lymphangioleiomyomatosis, a hyperproliferative disorder of lung smooth muscle cells with mutations in both alleles of either TSC1 or TSC2. A subset of these tumor cells expresses the melanoma-associated antigens gp100 and melanoma antigen recognized by T cells (MART-1). To explore the feasibility of targeting tumors in lymphangioleiomyomatosis by melanoma immunotherapy, we therefore assessed melanoma target antigen expression and existing immune infiltration of affected tissue compared with normal lung and melanoma as well as the susceptibility of cultured lymphangioleiomyomatosis cells to melanoma reactive cytotoxic T lymphocytes in vitro. Tumors expressed tyrosinase-related proteins 1 and 2 but not tyrosinase, in addition to gp100 and MART-1, and were densely infiltrated by macrophages, but not dendritic cells or T cell subsets. Although CD8(+) lymphocytes were sparse compared with melanoma, cells cultured from lymphangioleiomyomatosis tissue were susceptible to cytotoxic, gp100 reactive, and major histocompatibility complex class I restricted CD8(+) T cells in functional assays. Responder T cells selectively clustered and secreted interferon-gamma in response to HLA-matched melanocytes and cultured lymphangioleiomyomatosis cells. This reactivity exceeded that based on detectable gp100 expression; thus, tumor cells in lymphangioleiomyomatosis may process melanosomal antigens different from melanocytic cells. Therefore, boosting immune responses to gp100 in lymphangioleiomyomatosis may offer a highly desirable treatment option for this condition.

Antitumor immunity and cancer stem cells

Self-renewing cancer stem cells (CSC) capable of spawning more differentiated tumor cell progeny are required for tumorigenesis and neoplastic progression of leukemias and several solid cancers. The mechanisms by which CSC cause tumor initiation and growth are currently unknown. Recent findings that suggest a negative correlation between degrees of host immunocompetence and rates of cancer development raise the possibility that only a restricted minority of malignant cells, namely CSC, may possess the phenotypic and functional characteristics to evade host antitumor immunity. In human malignant melanoma, a highly immunogenic cancer, we recently identified malignant melanoma initiating cells (MMIC), a novel type of CSC, based on selective expression of the chemoresistance mediator ABCB5. Here we present evidence of a relative immune privilege of ABCB5(+) MMIC, suggesting refractoriness to current immunotherapeutic treatment strategies. We discuss our findings in the context of established immunomodulatory functions of physiologic stem cells and in relation to mechanisms responsible for the downregulation of immune responses against tumors. We propose that the MMIC subset might be responsible for melanoma immune evasion and that immunomodulation might represent one mechanism by which CSC advance tumorigenic growth and resistance to immunotherapy. Accordingly, the possibility of an MMIC-driven tumor escape from immune-mediated rejection has important implications for current melanoma immunotherapy.

A review of immunomodulators with reference to Canova

Immunomodulators are substances which modify the immunity of an individual to favour a particular immunological response. The immune response and the function of the immune response regulation process are described, with special reference to cancer and autoimmune disease. Homeopathy and its role in immune regulation are discussed with special reference to Canova. Canova is a homeopathic product produced, according to the Hahnemannian homeopathic method, in Brazil. Its role in cancer, bone marrow and haematopoiesis as well as macrophage and monocyte activation is reviewed. Canova seems to stabilize platelet morphology in human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS). The data suggest that the future of immunomodulators and homeopathic products which appear to have an effect on the immune response requires a better understanding of the relative need for immune activation versus immune modulation. Homeopathic products specifically need more attention.

Phase II, randomized, controlled, double-blinded trial of weekly elesclomol plus paclitaxel versus paclitaxel alone for stage IV metastatic melanoma

PURPOSE

Elesclomol is a novel, small-molecule, oxidative stress inducer believed to exert selective cytotoxicity by increasing intracellular concentrations of reactive oxygen species, which results in cell death via mitochondrial apoptosis. We evaluated whether the addition of elesclomol to weekly paclitaxel could improve efficacy in patients with stage IV metastatic melanoma.

PATIENTS AND METHODS

We randomly assigned patients with metastatic melanoma, measurable disease, and one or fewer prior chemotherapy regimens to elesclomol 213 mg/m(2) plus paclitaxel 80 mg/m(2) (E + P) or to paclitaxel 80 mg/m(2) alone at a 2:1 ratio; regimens were given as a 1-hour intravenous infusion weekly, during 3 of every 4 weeks until disease progression per Response Evaluation Criteria in Solid Tumors or death occurred. Patients who experienced progression were unblended, and patients on paclitaxel alone were permitted to cross over to E + P. The primary efficacy end point was progression-free survival (PFS); secondary end points were response rate (RR), toxicity, and overall survival (OS; analyzed post hoc).

RESULTS

At 21 US sites, 53 patients were randomly assigned to E + P, and 28 patients were randomly assigned to paclitaxel. The addition of elesclomol to paclitaxel yielded a doubling of median PFS (112 v 56 days) and a 41.7% risk reduction for disease progression/death (hazard ratio, 0.583; P = .035). Respective RRs for the E + P and paclitaxel groups were 15% and 3%; median OS was 11.9 v 7.8 months. Of patients on paclitaxel alone, 19 (68%) of 28 crossed over to E + P after they experienced progression. Weekly E + P was well tolerated.

CONCLUSION

E + P resulted in a statistically significant doubling of median PFS, with an acceptable toxicity profile and encouraging OS. A multinational, phase III trial (SYMMETRY) of E + P compared with paclitaxel alone in metastatic melanoma has closed.

Despite IFN-lambda receptor expression, blood immune cells, but not keratinocytes or melanocytes, have an impaired response to type III interferons: implications for therapeutic applications of these cytokines

Interferon (IFN)-lambda1, -2 and -3 (also designated as interleukin (IL)-29, IL-28alpha and IL-28beta) represent a new subfamily within the class II cytokine family. They show type I IFN-like antiviral and cytostatic activities in affected cells forming the basis for IFN-lambda1 therapy currently under development for hepatitis C infection. However, many aspects of IFN-lambdas are still unknown. This study aimed at identifying the target cells of IFN-lambdas within the immune system and the skin. Among skin cell populations, keratinocytes and melanocytes, but not fibroblasts, endothelial cells or subcutaneous adipocytes turned out to be targets. In contrast to these target cells, blood immune cell populations did not clearly respond to even high concentrations of these cytokines, despite an IFN-lambda receptor expression. Interestingly, immune cells expressed high levels of a short IFN-lambda receptor splice variant (sIFN-lambdaR1/sIL-28R1). Its characterization revealed a secreted, glycosylated protein that binds IFN-lambda1 with a moderate affinity (K(D) 73 nM) and was able to inhibit IFN-lambda1 effects. Our study suggests that IFN-lambda therapy should be suited for patients with verrucae, melanomas and non-melanoma skin cancers, apart from patients with viral hepatitis, and would not be accompanied by immune-mediated complications known from type I IFN application.

Infliximab in the treatment of anti-CTLA4 antibody (ipilimumab) induced immune-related colitis

The anti-CTLA4 antibody, ipilimumab, has shown clinical activity against melanoma. Diarrhea due to immune-related colitis is the most frequent serious toxicity and, if untreated, may lead to intestinal perforation. Diarrhea treatment guidelines were developed based on clinical experience in over 2000 patients treated with ipilimumab, and these safety guidelines recommend systemic steroids as the first choice for the treatment of severe diarrhea. In this article, we present an alternative approach to the control of immune-related colitis by using the antitumor necrosis factor antibody, infliximab. Patients with metastatic melanoma received ipilimumab 10 mg/kg every 3 weeks for 4 doses, then every 3 months. Those who developed grade 2 diarrhea were treated with infliximab 5 mg/kg weeks 0 and 2 with mesalamine and loperamide. Steroids were given only for refractory cases requiring hospitalization. Of the first 3 cases of ipilimumab-induced diarrhea, 2 proved refractory and required hospitalization, but 1 recovered quickly without systemic steroids. We then added hydrocortisone enemas daily to the above regimen, and the next 3 patients recovered from grade 2 ipilimumab-induced colitis without difficulty. Treatment with infliximab, mesalamine, and hydrocortisone enemas may produce a rapid improvement in ipilimumab-induced colitis and avoid the administration of systemic steroids.

Cancer immunotherapy

Recent scientific advances have expanded our understanding of the immune system and its response to malignant cells. The clinical goal of tumour immunotherapy is to provide either passive or active immunity against malignancies by harnessing the immune system to target tumours. Monoclonal antibodies, cytokines, cellular immunotherapy, and vaccines have increasingly become successful therapeutic agents for the treatment of solid and haematological cancers in preclinical models, clinical trials, and practice. In this article, we review recent advances in the immunotherapy of cancer, focusing on new strategies and future perspectives as well as on clinical trials attempting to enhance the efficacy of immunotherapeutic modalities and translate this knowledge into effective cancer therapies.

Tumor dormancy and metastasis

Metastasis--the spread of cancer to distant organs--is responsible for most cancer deaths. Current adjuvant therapy is based on prognostic indicators that stratify patients into defined risk groups. However, some patients believed to have a good prognosis nonetheless develop metastases, in some cases many years after apparently successful treatment of their primary cancer. This period of clinical dormancy leads to many questions about how best to manage patients, including how to better assign risk of late recurrence, how long to monitor patients, and whether some patients will benefit from extended therapy to prevent late recurrences. The development of targeted therapies with fewer side effects is leading to clinical trials aimed at determining the effectiveness of such long-term therapy. However, much remains to be learned about tumor dormancy. Experimental studies are shedding light on biological and molecular mechanisms potentially responsible for tumor dormancy. Emerging research into tumor initiating cells, immunotherapy, and metastasis suppressor genes, may lead to new approaches for targeted antimetastatic therapy to prolong tumor dormancy. An improved understanding of tumor dormancy is needed for better management of patients at risk for late-developing metastases.

Recent advances on skin-resident stem/progenitor cell functions in skin regeneration, aging and cancers and novel anti-aging and cancer therapies

Recent advances in skin-resident adult stem/progenitor cell research have revealed that these immature and regenerative cells with a high longevity provide critical functions in maintaining skin homeostasis and repair after severe injuries along the lifespan of individuals. The establishment of the functional properties of distinct adult stem/progenitor cells found in skin epidermis and hair follicles and extrinsic signals from their niches, which are deregulated during their aging and malignant transformation, has significantly improved our understanding on the etiopathogenesis of diverse human skin disorders and cancers. Particularly, enhanced ultraviolet radiation exposure, inflammation and oxidative stress and telomere attrition during chronological aging may induce severe DNA damages and genomic instability in the skin-resident stem/progenitor cells and their progenies. These molecular events may result in the alterations in key signalling components controlling their self-renewal and/or regenerative capacities as well as the activation of tumour suppressor gene products that trigger their growth arrest and senescence or apoptotic death. The progressive decline in the regenerative functions and/or number of skin-resident adult stem/progenitor cells may cause diverse skin diseases with advancing age. Moreover, the photoaging, telomerase re-activation and occurrence of different oncogenic events in skin-resident adult stem/progenitor cells may also culminate in their malignant transformation into cancer stem/progenitor cells and skin cancer initiation and progression. Therefore, the anti-inflammatory and anti-oxidant treatments and stem cell-replacement and gene therapies as well as the molecular targeting of their malignant counterpart, skin cancer-initiating cells offer great promise to treat diverse skin disorders and cancers.

Autoimmune thyroiditis as an indicator of autoimmune sequelae during cancer immunotherapy

Improving cancer immunotherapy by targeting T cell network also triggers autoimmunity. We disrupted regulatory T cell (Treg) function to probe the balance between breast cancer vaccination and autoimmune thyroiditis (EAT) in four models, with particular attention to MHC-associated susceptibility, EAT induction with mouse thyroglobulin (mTg) without adjuvant, and tolerance to Her-2/neu in transgenic mice. 1) In EAT-resistant BALB/c mice, Treg depletion enhanced tumor regression, and facilitated mild thyroiditis induction. 2) In Her-2 tolerant C57BL/6 mice expressing HLA-DR3, an EAT-susceptibility allele, Her-2 DNA vaccinations must follow Treg depletion for (Her-2xDR3)F(1) mice to resist tumor challenge; thyroiditis incidence was moderated by the EAT-resistant IA(b) allele. 3) In neu tolerant, EAT-resistant BALB/c mice, implanted neu(+) tumor also regressed only after Treg depletion and DNA vaccinations. Tumor immunity was long-term, providing protection from spontaneous tumorigenesis. In all three, immune stimuli from concurrent tumor regression and EAT development have a noticeable, mutually augmenting effect. 4) In Treg-depleted, EAT-susceptible CBA/J mice, strong tumor protection was established by immunization with a cell vaccine. mTg injections led to greater thyroiditis incidence and severity. Combination models with MHC class II diversity should facilitate autoimmunity risk assessment and management while generating tumor immunity.

Tricking melanoma to self-digest: a deal of a meal!

Melanoma cells acquire multiple genetic and epigenetic alterations that promote their metastasis and resistance to available therapies. In this issue of Cancer Cell, Soengas and colleagues reveal that the induction of endosome-mediated autophagy results in efficient melanoma cell death, thereby offering new potential means for treatment of this devastating cancer.

Targeted activation of innate immunity for therapeutic induction of autophagy and apoptosis in melanoma cells

Inappropriate drug delivery, secondary toxicities, and persistent chemo- and immunoresistance have traditionally compromised treatment response in melanoma. Using cellular systems and genetically engineered mouse models, we show that melanoma cells retain an innate ability to recognize cytosolic double-stranded RNA (dsRNA) and mount persistent stress response programs able to block tumor growth, even in highly immunosuppressed backgrounds. The dsRNA mimic polyinosine-polycytidylic acid, coadministered with polyethyleneimine as carrier, was identified as an unanticipated inducer of autophagy downstream of an exacerbated endosomal maturation program. A concurrent activity of the dsRNA helicase MDA-5 driving the proapoptotic protein NOXA resulted in an efficient autodigestion of melanoma cells. These results reveal tractable links for therapeutic intervention among dsRNA helicases, endo/lysosomes, and apoptotic factors.

PD1 blockade reverses the suppression of melanoma antigen-specific CTL by CD4+ CD25(Hi) regulatory T cells

Regulatory CD4(+)CD25(Hi) T cells (Treg) and programmed death-1 (PD-1) molecule have emerged as pivotal players in immune regulation. However, the underlying mechanisms by which they impact antigen-specific CD8(+) immune responses in cancer patients and how they interact with each other under physiologic conditions remain unclear. Herein, we examined the relationship of PD-1 and its abrogation to the function of Treg in patients with melanoma using short-term in vitro assays to generate melanoma-specific T cells. We identified Treg in the circulation of vaccinated melanoma patients and detected PD-1 expression on vaccine-induced melanoma antigen-specific CTLs, as well as on and within Treg from patients' peripheral blood. Programmed death ligand (PD-L) 1 expression was also detected on patients' Treg. PD-1 blockade promoted the generation of melanoma antigen-specific CTLs and masked their inhibition by Treg. The mechanisms by which PD-1 blockade mediated immune enhancement included direct augmentation of melanoma antigen-specific CTL proliferation, heightening their resistance to inhibition by Treg and direct limitation of the inhibitory ability of Treg. PD-1 blockade reversed the increased expression of PD-1 and PD-L1 on melanoma antigen-specific CTL by Treg, rescued INF-gamma and IL-2 or INF-gamma and tumor necrosis factor-alpha co-expression and expression of IL-7 receptor by melanoma antigen-specific CTL which were diminished by Treg. PD-1 blockade also resulted in down-regulation of intracellular FoxP3 expression by Treg. These data suggest that PD-1 is importantly implicated in the regulation of Treg function in melanoma patients.

Effects of methyl-beta-cyclodextrin treatment on secretion profile of interferon-beta and zonula occuludin-1 architecture in Madin-Darby canine kidney cell monolayers

The interferon (IFN) is a paradigm of secretory protein. However, it has been poorly understood how its secretion is regulated in polarized epithelial cells. Recently, we had shown that exogenous IFNs transiently expressed in polarized monolayers were predominantly secreted to the side on which gene transfection had been performed, while stably expressed IFNs were secreted almost equally to the both cell sides. Since those modes of secretion did not affect each other, epithelial cell layers seemed to have at least two protein sorting/secretion pathways, one for transient expression and the other for stable expression, for identical secretory proteins. Furthermore, this dual secretion profile seemed to be mediated by distinct post-trans Golgi network vesicles, suggesting the involvement of lipid rafts in the sorting multiplicity. To address this issue, here we studied the effects of cholesterol depletion with methyl-beta-cyclodextrin (MbetaCD) on the secretion profile of IFN-beta exogenously expressed in Madin-Darby canine kidney (MDCK) cells. The MbetaCD-treatment, however, did not affect the profile in either transient or stable expression, although the architecture of zonula occuludin-1, which links to the tight junction, was substantially disrupted by the treatment. Further analysis of Triton X-100-insoluble cell extracts by sucrose density centrifugation demonstrated that IFN-beta was not apparently associated with lipid rafts in either transient or stable expression. These results suggest that lipid rafts may not be crucially involved in the regulation of secretion polarity of IFN-beta in the epithelial cells.

Identification of a 17beta-hydroxysteroid dehydrogenase type 12 pseudogene as the source of a highly restricted BALB/c Meth A tumor rejection peptide

Mass spectrometric analysis identified the peptide recognized by a cytotoxic T lymphocyte (CTL) specific for the chemically induced BALB/c Meth A sarcoma as derived from a 17beta-hydroxysteroid dehydrogenase type 12 (Hsd17b12) pseudogene present in the BALB/c genome, but only expressed in Meth A sarcoma. The sequence of the peptide is TYDKIKTGL and corresponds to Hsd17b12(114-122) with threonine instead of isoleucine at codon 114 and is designated Hsd17b12(114T). Immunization of mice with an Hsd17b12(114T) peptide-pulsed dendritic cell-based vaccine or a non-viral plasmid construct expressing the Hsd17b12(114T) peptide protected the mice from lethal Meth A tumor challenge in tumor rejection assays. A Hsd17b12(114-122) peptide-pulsed vaccine was ineffective in inducing resistance in mice to Meth A sarcoma. These results confirm the immunogenicity of the identified tumor peptide, as well as demonstrate the efficacies of these vaccine vehicles. These findings suggest that the role of the human homolog of Hsd17b12, HSD17B12, as a potential human tumor antigen be explored.

Emerging concepts in biomarker discovery; the US-Japan Workshop on Immunological Molecular Markers in Oncology

Supported by the Office of International Affairs, National Cancer Institute (NCI), the "US-Japan Workshop on Immunological Biomarkers in Oncology" was held in March 2009. The workshop was related to a task force launched by the International Society for the Biological Therapy of Cancer (iSBTc) and the United States Food and Drug Administration (FDA) to identify strategies for biomarker discovery and validation in the field of biotherapy. The effort will culminate on October 28th 2009 in the "iSBTc-FDA-NCI Workshop on Prognostic and Predictive Immunologic Biomarkers in Cancer", which will be held in Washington DC in association with the Annual Meeting. The purposes of the US-Japan workshop were a) to discuss novel approaches to enhance the discovery of predictive and/or prognostic markers in cancer immunotherapy; b) to define the state of the science in biomarker discovery and validation. The participation of Japanese and US scientists provided the opportunity to identify shared or discordant themes across the distinct immune genetic background and the diverse prevalence of disease between the two Nations. Converging concepts were identified: enhanced knowledge of interferon-related pathways was found to be central to the understanding of immune-mediated tissue-specific destruction (TSD) of which tumor rejection is a representative facet. Although the expression of interferon-stimulated genes (ISGs) likely mediates the inflammatory process leading to tumor rejection, it is insufficient by itself and the associated mechanisms need to be identified. It is likely that adaptive immune responses play a broader role in tumor rejection than those strictly related to their antigen-specificity; likely, their primary role is to trigger an acute and tissue-specific inflammatory response at the tumor site that leads to rejection upon recruitment of additional innate and adaptive immune mechanisms. Other candidate systemic and/or tissue-specific biomarkers were recognized that might be added to the list of known entities applicable in immunotherapy trials. The need for a systematic approach to biomarker discovery that takes advantage of powerful high-throughput technologies was recognized; it was clear from the current state of the science that immunotherapy is still in a discovery phase and only a few of the current biomarkers warrant extensive validation. It was, finally, clear that, while current technologies have almost limitless potential, inadequate study design, limited standardization and cross-validation among laboratories and suboptimal comparability of data remain major road blocks. The institution of an interactive consortium for high throughput molecular monitoring of clinical trials with voluntary participation might provide cost-effective solutions.

Ig-like transcript 3 regulates expression of proinflammatory cytokines and migration of activated T cells

Ig-like transcript 3 (ILT3), an inhibitory receptor expressed by APC is involved in functional shaping of T cell responses toward a tolerant state. We have previously demonstrated that membrane (m) and soluble (s) ILT3 induce allogeneic tolerance to human islet cells in humanized NOD/SCID mice. Recombinant sILT3 induces the differentiation of CD8(+) T suppressor cells both in vivo and in vitro. To better understand the molecular mechanisms by which ILT3 suppresses immune responses, we have generated ILT3 knockdown (ILT3KD) dendritic cells (DC) and analyzed the phenotypic and functional characteristics of these cells. In this study, we report that silencing of ILT3 expression in DC (ILT3KD DC) increases TLR responsiveness to their specific ligands as reflected in increased synthesis and secretion of proinflammatory cytokines such as IL-1alpha, IL-1beta, and IL-6 and type I IFN. ILT3KD-DC also secretes more CXCL10 and CXCL11 chemokines in response to TLR ligation, thus accelerating T cell migration in diffusion chamber experiments. ILT3KD-DC elicit increased T cell proliferation and synthesis of proinflammatory cytokines IFN-gamma and IL-17A both in MLC and in culture with autologous DC pulsed with CMV protein. ILT3 signaling results in inhibition of NF-kappaB and, to a lesser extent, MAPK p38 pathways in DC. Our results suggest that ILT3 plays a critical role in the control of inflammation.

Multidisciplinary treatment of primary melanoma

This article covers the multidisciplinary treatment of primary melanoma. Excision margins and the need for sentinel lymphadenectomy are mainly dictated by the Breslow thickness although exceptions to this dictum do exist. Interferon is the only FDA approved adjuvant therapy for high risk melanoma although its overall survival benefit is minimal. Trials examining different doses or duration of interferon therapy have not demonstrated any promising survival data so far. There have been several randomized vaccine trials for melanoma but none have shown an overall survival benefit. Research into T-cell regulation continues and will hopefully bring promise for the future of melanoma treatment.

Inflammation and melanoma metastasis

Metastatic melanoma is extremely refractory to existing chemotherapeutic drugs and bioimmune adjuvant therapies, and the life span of patients with metastatic melanoma is often measured in months. Understanding the mechanisms responsible for the development of tumor metastasis is critical for finding successful curative measures. An expending amount of data reveal the importance of inflammatory microenvironment and stroma in cancer initiation and progression, which brings new directions and approaches to cancer treatment. This review will summarize current data on the role of the tumor microenvironment in shaping the metastatic phenotype of melanoma.

Clinical and biological efficacy of recombinant human interleukin-21 in patients with stage IV malignant melanoma without prior treatment: a phase IIa trial

PURPOSE

Human interleukin-21 (IL-21) is a class I cytokine that mediates activation of CD8(+) T cells, natural killer (NK) cells, and other cell types. We report final clinical and biological results of a phase II study of recombinant human IL-21 (rIL-21) in patients with metastatic melanoma.

EXPERIMENTAL DESIGN

Open-label, single-arm, two-stage trial.

ELIGIBILITY CRITERIA

unresectable metastatic melanoma, measurable disease by Response Evaluation Criteria in Solid Tumors, no prior systemic therapy (adjuvant IFN permitted), adequate major organ function, good performance status, no significant autoimmune disease, and life expectancy at least 4 months.

PRIMARY OBJECTIVE

antitumor efficacy (response rate).

SECONDARY OBJECTIVES

safety, blood biomarkers, and generation of anti-rIL-21 antibodies. rIL-21 (30 microg/kg/dose) was administered by intravenous bolus injection in 8-week cycles (5 dosing days followed by 9 days of rest for 6 weeks and then 2 weeks off treatment).

RESULTS

Stage I of the study comprised 14 patients. One confirmed complete response (CR) was observed, and as per protocol, 10 more patients were accrued to stage II (total n = 24: 10 female and 14 male). Best tumor response included one confirmed CR and one confirmed partial response, both with lung metastases. Treatment was overall well tolerated. Biomarker analyses showed increases in serum soluble CD25, frequencies of CD25(+) NK and CD8(+) T cells, and mRNA for IFN-gamma, perforin, and granzyme B in CD8(+) T and NK cells.

CONCLUSIONS

rIL-21 administered at 30 microg/kg/d in 5-day cycles every second week is biologically active and well tolerated in patients with metastatic melanoma. Confirmed responses, including one CR, were observed.