Trial watch: FDA-approved Toll-like receptor agonists for cancer therapy

Toll-like receptors (TLRs) have first been characterized for their capacity to detect conserved microbial components like lipopolysaccharide (LPS) and double-stranded RNA, resulting in the elicitation of potent (innate) immune responses against invading pathogens. More recently, TLRs have also been shown to promote the activation of the cognate immune system against cancer cells. Today, only three TLR agonists are approved by FDA for use in humans: the bacillus Calmette-Guérin (BCG), monophosphoryl lipid A (MPL) and imiquimod. BCG (an attenuated strain of Mycobacterium bovis) is mainly used as a vaccine against tuberculosis, but also for the immunotherapy of in situ bladder carcinoma. MPL (derived from the LPS of Salmonella minnesota) is included in the formulation of Cervarix®, a vaccine against human papillomavirus-16 and -18. Imiquimod (a synthetic imidazoquinoline) is routinely employed for actinic keratosis, superficial basal cell carcinoma, and external genital warts (condylomata acuminata). In this Trial Watch, we will summarize the results of recently completed clinical trials and discuss the progress of ongoing studies that have evaluated/are evaluating FDA-approved TLR agonists as off-label medications for cancer therapy.

A genetic inference on cancer immune responsiveness

A cancer immune signature implicating good prognosis and responsiveness to immunotherapy was described that is observed also in other aspects of immune-mediated, tissue-specific destruction (TSD). Its determinism remains, however, elusive. Based on limited but unique clinical observations, we propose a multifactorial genetic model of human cancer immune responsiveness.

Therapeutic Cancer Vaccination with Ex Vivo RNA-Transfected Dendritic Cells-An Update

Over the last two decades, dendritic cell (DC) vaccination has been studied extensively as active immunotherapy in cancer treatment and has been proven safe in all clinical trials both with respect to short and long-term side effects. For antigen-loading of dendritic cells (DCs) one method is to introduce mRNA coding for the desired antigens. To target the whole antigenic repertoire of a tumor, even the total tumor mRNA of a macrodissected biopsy sample can be used. To date, reports have been published on a total of 781 patients suffering from different tumor entities and HIV-infection, who have been treated with DCs loaded with mRNA. The majority of those were melanoma patients, followed by HIV-infected patients, but leukemias, brain tumors, prostate cancer, renal cell carcinomas, pancreatic cancers and several others have also been treated. Next to antigen-loading, mRNA-electroporation allows a purposeful manipulation of the DCs’ phenotype and function to enhance their immunogenicity. In this review, we intend to give a comprehensive summary of what has been published regarding clinical testing of ex vivo generated mRNA-transfected DCs, with respect to safety and risk/benefit evaluations, choice of tumor antigens and RNA-source, and the design of better DCs for vaccination by transfection of mRNA-encoded functional proteins.

Expression profiles of immune-related genes are associated with neoadjuvant ipilimumab clinical benefit

Purpose: Patients with regionally advanced melanoma were treated with neoadjuvant ipilimumab in a previously reported study (PLOS One 2014). Gene expression profiles of tumors of treated patients were investigated for their association with immunotherapeutic benefit. Methods: Patients were treated with ipilimumab (10 mg/kg intravenously every 3 weeks × 2 doses) before and after surgery. Tumor specimens were obtained at baseline and at definitive surgery (weeks 6-8). Gene expression profiling was performed on the tumor biopsies of 27 patients. The primary endpoint was mRNA expression profiling using U133A 2.0 Affymetrix gene chips. Significance analysis of microarrays was performed to test the association of each gene with outcome. Pathway analysis was performed using Ingenuity Pathway Analysis software. The Benjamini and Hochberg method was used to adjust for multiple testing in the pathway analysis. Results: Pathway analysis identified biologically relevant pathways enriched with genes that are significantly associated with clinical outcome at baseline in relation to relapse-free survival (RFS) and disease non-progression (as assessed preoperatively at week 6) as well as early on-treatment (RFS and overall survival). The molecules and pathways that achieved differential expression of highest statistical significance were notably immune related. Association of the gene signature with clinical outcome overlapped between baseline and on-treatment specimens and across clinical endpoints tested. Conclusion: Gene expression profiling identified a signature reflecting an immune active and proinflammatory tumor microenvironment that derived clinical benefit from neoadjuvant ipilimumab at baseline and early on-treatment. These findings warrant further investigation in relation to ipilimumab and other immunotherapeutics.

Immune checkpoint inhibitors in melanoma

The potential to harness the power of the immune system and effectively treat patients with metastatic melanoma is finally being realized with the advent of immune checkpoint inhibitors. These new therapies herald a new era in the treatment of melanoma with the potential to produce very durable responses and possible cure for a subset of patients, though bring with them challenges including novel toxicities and nonconventional response patterns. This article reviews the currently available immune checkpoint inhibitors, potential biomarkers to predict response and promising investigational approaches including combination therapies.

Beyond CTLA-4: novel immunotherapy strategies for metastatic melanoma

The treatment of metastatic melanoma is rapidly evolving. The discovery of BRAF and MEK inhibitors was an important milestone. Unfortunately, although response rates are high, disease progression is universal. Despite the success of IL-2 and adjuvant IFL-α2b, these two agents remained the only approved immunotherapy approaches. In recent years, the use of immunotherapy has drawn attention with the recognition of the mechanisms of tumor immune evasion. Blockade of these mechanisms may improve outcomes. However, the potential adverse events, the optimal use of these modalities, the high cost and the absence of predictive markers remain unmet challenges. Herein, we review the immunotherapy strategies in melanoma, either approved or under evaluation, and present the relevant data concerning their efficacy and safety.

Molecular markers in melanoma

The last few years have witnessed the dawn of the molecular era in melanoma treatment. With the advent of successful therapy targeting mutant BRAF, melanoma is leading the field of cancer research in the molecular approach to therapy of advanced disease. Attempting to keep pace with advances in therapy are advances in the molecular assessment of melanoma progression, facilitated by the availability of genome-wide approaches to interrogate the malignant phenotype. At the DNA level, this has included approaches such as comparative genomic hybridization. At the RNA level, this has consisted of gene expression profiling using various assay methodologies. In certain instances, markers identified using these platforms have been further examined and developed using fluorescence in situ hybridization and immunohistochemical analysis. In this article, we will review recent progress in the development of novel molecular markers for melanoma that are nearing clinical application. We will review developments in the molecular classification of melanoma, in the molecular diagnosis of melanoma, and in the molecular assessment of melanoma prognosis.

Advances in the management of melanoma: targeted therapy, immunotherapy and future directions

Metastatic melanoma is an aggressive, immunogenic and molecularly heterogeneous disease for which most patients require systemic treatment. Recently, significant clinical breakthroughs have revolutionized the treatment of advanced melanoma, leading to the licensing of ipilimumab, a monoclonal antibody targeting cytotoxic T-lymphocyte-associated antigen 4, and vemurafenib, a BRAF inhibitor used in patients whose tumors contain a V600 mutation in the BRAF gene. This recent success has led to optimism and momentum has gathered with updated trial results from these therapies, next-generation compounds that target validated molecular pathways and novel agents that are mechanistically distinct. This review summarizes the recent advances and updated results since the licensing of vemurafenib and ipilimumab, the benefits and limitations of these agents, future strategies to improve upon existing treatments and overcome acquired resistance, in-progress and future clinical trials, as well as novel therapeutic targets, pathways and therapies that hold promise in advancing clinical benefit.

Cancer immunotherapy strategies based on overcoming barriers within the tumor microenvironment

For tumor antigen-specific T cells to effectively control the growth of cancer cells in vivo, they must gain access to, and function within, the tumor microenvironment. While tumor antigen-based vaccines and T cell adoptive transfer strategies can result in clinical benefit in a subset of patients, most of the patients do not respond clinically. Even for tumor-infiltrating lymphocyte (TIL)-based adoptive transfer for patients with metastatic melanoma, which can provide tumor shrinkage in around 50% of treated individuals, many patients are not eligible, in part because there are not sufficient TIL present in the resected tumor. Thus, the denominator is in fact larger, and it has been suggested that absence of TIL may be a marker for poor efficacy of immunotherapies in general. While qualitative and/or quantitative features of the T cells are important considerations for efficacy, a major component of primary resistance likely can be attributed to the tumor microenvironment. Data are accumulating suggesting that two major categories of immune resistance within the tumor microenvironment may exist: failure of T cell trafficking due to low levels of inflammation and lack of chemokines for migration, and dominant suppression through immune inhibitory mechanisms. New therapeutic interventions are being guided by these observations, and preliminary clinical success is validating this working model.

Comparative clinical benefits of systemic adjuvant therapy for paradigm solid tumors

Adjuvant therapy employing cytotoxic chemotherapy, molecularly targeted agents, immunologic, and hormonal agents has shown a significant impact upon a variety of solid tumors. The principles that guide adjuvant therapy differ among various tumor types and specific modalities, but generally indicate a greater impact of therapy in the postsurgical setting of micrometastatic disease, for which adjuvant therapy is commonly pursued, vs. the setting of gross unresectable disease. This review of adjuvant therapies in current use for five major solid tumors highlights the rationale for current effective adjuvant therapy, and draws comparisons between the adjuvant regimens that have found application in solid tumors.

Biomarkers and correlative endpoints for immunotherapy trials

Immunotherapies for lung cancer are reaching phase III clinical trial, but the ultimate success likely will depend on developing biomarkers to guide development and choosing patient populations most likely to benefit. Because the immune response to cancer involves multiple cell types and cytokines, some spatially and temporally separated, it is likely that multiple biomarkers will be required to fully characterize efficacy of the vaccine and predict eventual benefit. Peripheral blood markers of response, such as the ELISPOT assay and cytokine flow cytometry analyses of peripheral blood mononuclear cells following immunotherapy, remain the standard approach, but it is increasingly important to obtain tissue to study the immune response at the site of the tumor. Earlier clinical endpoints such as response rate and progression-free survival do not correlate with overall survival demonstrated for some immunotherapies, suggesting the need to develop other intermediary clinical endpoints. Insofar as all these biomarkers and surrogate endpoints are relevant in multiple malignancies, it may be possible to extrapolate findings to immunotherapy of lung cancer.

IFN-α in the treatment of melanoma

Among the IFNs, IFN-α2 has been the most broadly evaluated clinically. At the molecular level, IFN-α has multiple effects in a variety of malignancies that range from antiangiogenic to potent immunoregulatory, differentiation-inducing, antiproliferative, and proapoptotic effects. A multitude of IFN-α2 regimens that may be classified as low dose, intermediate dose, and high dose have been evaluated as adjuvant therapy in melanoma. A durable impact on both relapse-free and overall survival was seen only with the regimen utilizing high-dose IFN-α2b tested in the Eastern Cooperative Oncology Group and intergroup trials E1684, E1690, and E1694 as adjuvant therapy for high-risk surgically resected melanoma (stage IIB or III). Adjuvant pegylated IFN-α2b has also been evaluated at maximally tolerable doses compared with the observation group in the European Organization for Research and Treatment of Cancer trial 18991 and has shown relapse-free survival benefits in patients with microscopic nodal disease.

Reflections upon human cancer immune responsiveness to T cell-based therapy

Immune-mediated rejection of human cancer is a relatively rare but well-documented phenomenon. Its rate of occurrence progressively increases from the occasional observation of spontaneous regressions to the high rate of complete remissions observed in response to effective treatments. For two decades, our group has focused its interest in understanding this phenomenon by studying humans following an inductive approach. Sticking to a sequential logic, we dissected the phenomenon by studying to the best of our capability both peripheral and tumor samples and reached the conclusion that immune-mediated cancer rejection is a facet of autoimmunity where the target tissue is the cancer itself. As we are currently defining the strategy to effectively identify the mechanisms leading in individual patients to rejection of their own tumors, we considered useful to summarize the thought process that guided us to our own interpretation of the mechanisms of immune responsiveness.

Vaccines in non-small cell lung cancer: rationale, combination strategies and update on clinical trials

Non-small cell lung cancer (NSCLC) remains the leading cause of cancer related mortality worldwide and despite some advances in therapy the overall prognosis remains disappointing. New therapeutic approaches like vaccination have been proposed and several clinical trials are ongoing. Many tumor antigens have been identified so far and specific tumor vaccines targeting these antigens have been developed. Even if the ideal setting for vaccine therapy might be the adjuvant one, vaccines seem to be potentially beneficial also in advanced disease and combination therapy could be a promising treatment option. In the advanced setting anti-MUC-1 vaccine (belagenpumatucel) and anti-TGF-β(2) vaccine (BPL-25) have entered in phase III trials as maintenance therapy after first line chemotherapy. In the adjuvant setting the most relevant and promising vaccines are directed against MAGE-A3 and PRAME, respectively. We will review the key points for effective active immunotherapies and combination therapies, giving an update on the most promising vaccines developed in NSCLC.

Cancer immunotherapy

The remarkable specificity of the immune system through antigen recognition has long attracted investigators to the possibility of immune-based therapy for cancer. Previous cancer immunotherapeutics had been restricted to non-specific immunomodulatory agents, such as the cytokines IL-2 or IFN-α. However, the molecular definition of cancer-associated antigens introduced the possibility of specific vaccines and adoptive T cell approaches aiming to target the tumor cells more specifically. The recent introduction of total exome sequencing has enabled the identification of patient tumor-specific epitopes generated through somatic point mutations, raising the possibility of targeting tumor antigens in individual patients which are even more tumor-specific. Transcriptional profiling and immunohistochemistry analyses have revealed a subset of patients with a pre-existing T cell-inflamed tumor microenvironment. This phenotype may be predictive of clinical outcome to immunotherapies and offers the possibility of a predictive biomarker. Further analysis of these tumors has identified a set of defined immune suppressive factors which themselves are being targeted with new immunotherapeutics, already with interesting early phase clinical trial results. Understanding not only the expression of tumor antigens but also the dynamic between a growing tumor and the host immune response is thus generating a rich set of opportunities for the specific immunotherapy of cancer.

Advances in systemic treatment of melanoma

After decades of phase III trials failing to demonstrate an impact on survival of various drugs in metastatic melanoma there are finally significant advances in systemic therapies for melanoma emerging. Novel ways to modulate the immune system by monoclonal antibodies as well as various signalling pathway inhibitors are responsible for creating a whole new therapeutic landscape. For the first time it is likely that a number of new drugs with completely different mechanisms of action will be approved in the near future. The imminent candidates are the anti-CTLA-4 antibody ipilimumab, and the highly selective BRAF inhibitor PLX4032. But in each class other molecules are under development with good perspectives. Various new combinations will have to be explored and it is reasonable to expect synergies between the different classes of drugs as well as between novel molecules within the same class of drugs. Here, an overview of current developments and the most important new drugs under consideration is provided.

Molecular insights on the peripheral and intratumoral effects of systemic high-dose rIL-2 (aldesleukin) administration for the treatment of metastatic melanoma

PURPOSE

We have previously shown that within tumors, recombinant interleukin-2 (rIL-2, aldesleukin) consistently activates tumor-associated macrophages and upregulates IFN-stimulated genes while inducing minimal migration, activation, or proliferation of T cells. These effects are independent of tumor response to treatment. Here, we prospectively evaluated transcriptional alterations induced by rIL-2 in peripheral blood mononuclear cells (PBMC) and within melanoma metastases.

EXPERIMENTAL DESIGN

We evaluated gene expression changes by serially comparing pre- to posttreatment samples in 13 patients and also compared transcriptional differences among lesions displaying different responsiveness to therapy, focusing on 2 lesions decreasing in size and 2 remaining stable (responding lesions) compared with nonresponding ones.

RESULTS

As previously described, the effects of rIL-2 were dramatic within PBMCs, whereas effects within the tumor microenvironment were lesion specific and limited. However, distinct signatures specific to response could be observed in responding lesions pretreatment that were amplified following rIL-2 administration. These signatures match the functional profile observed in other human or experimental models in which immune-mediated tissue-specific destruction (TSD) occurs, underscoring common pathways leading to rejection. Moreover, the signatures observed in pretreatment lesions were qualitatively similar to those associated with TSD, underlining a determinism to immune responsiveness that depends upon the genetic background of the host or the intrinsic genetic makeup of individual tumors.

CONCLUSIONS

This is the first prospectively collected insight on global transcriptional events occurring during high-dose rIL-2 therapy in melanoma metastases responding to treatment.

An immunologic portrait of cancer

The advent of high-throughput technology challenges the traditional histopathological classification of cancer, and proposes new taxonomies derived from global transcriptional patterns. Although most of these molecular re-classifications did not endure the test of time, they provided bulk of new information that can reframe our understanding of human cancer biology. Here, we focus on an immunologic interpretation of cancer that segregates oncogenic processes independent from their tissue derivation into at least two categories of which one bears the footprints of immune activation. Several observations describe a cancer phenotype where the expression of interferon stimulated genes and immune effector mechanisms reflect patterns commonly observed during the inflammatory response against pathogens, which leads to elimination of infected cells. As these signatures are observed in growing cancers, they are not sufficient to entirely clear the organism of neoplastic cells but they sustain, as in chronic infections, a self-perpetuating inflammatory process. Yet, several studies determined an association between this inflammatory status and a favorable natural history of the disease or a better responsiveness to cancer immune therapy. Moreover, these signatures overlap with those observed during immune-mediated cancer rejection and, more broadly, immune-mediated tissue-specific destruction in other immune pathologies. Thus, a discussion concerning this cancer phenotype is warranted as it remains unknown why it occurs in immune competent hosts. It also remains uncertain whether a genetically determined response of the host to its own cancer, the genetic makeup of the neoplastic process or a combination of both drives the inflammatory process. Here we reflect on commonalities and discrepancies among studies and on the genetic or somatic conditions that may cause this schism in cancer behavior.

Tumor-infiltrating lymphocytes: apparently good for melanoma patients. But why?

Tumor-infiltrating T lymphocytes (TILs) are observed in a number of human primary or metastatic tumors. Recently, gene expression profiling experiments suggested that the presence of T cells in metastatic melanomas before vaccinating the patients with tumor antigens could be a biomarker for clinical benefit from the vaccines. In this context, we review results pertaining to TILs in human melanomas, their prognostic value, and some possible reasons why their presence could help in selecting melanoma patients for vaccination against tumor-specific antigens.

The trouble with translational medicine

Increasingly more reports in the literature are reflecting on the hurdles of effective translation from promising results of biomedical research into useful therapeutics. A recurrent theme is that good intentions are frustrated by extrinsic factors upon which 'translationalists' have little control. It is possible that the problem resides, at least in part, within the translational community itself, which has failed to prioritize the steps required to approach the problem systematically. Most importantly, there is disproportionate emphasis on bench-to-bedside efforts, rather than confronting a priori the need to increase the understanding of human pathophysiology. Thus, therapeutic concepts based on experimental conditions that may not and indeed often do not represent the nature of human genetics lead to drug development that is not sufficiently applicable to the human condition. The damage is then amplified when these ill-fated concepts are tested in clinical trials at great cost. The use of surrogate biomarkers that could allow early assessment of efficacy currently requires long-term assessment of clinical benefit. This can delay by years or decades essential feedback about clinical efficacy. Moreover, scant effort is applied to learning whether a drug has achieved its biological endpoint, or why it failed its clinical endpoint. Thus, the feedback loop is not only delayed, but is often uninformative. As a consequence, researchers continue to produce novel therapeutic candidates based on experimental models without the essential benefit of lessons learned from previous failures. Biomedical research will succeed when drug development is guided by experience gained through informative clinical trials with the purpose of not only testing the effectiveness of treatment but also providing mechanistic insights into the differences between expected and observed results. This can only be achieved through the courageous effort of the research community to change the way biomedical research is funded, published and rewarded.

The biology of cancer testis antigens: putative function, regulation and therapeutic potential

Cancer testis antigens (CTA) are a large family of tumor-associated antigens expressed in human tumors of different histological origin, but not in normal tissues except for testis and placenta. This tumor-restricted pattern of expression, together with their strong in vivo immunogenicity, identified CTA as ideal targets for tumor-specific immunotherapeutic approaches, and prompted the development of several clinical trials of CTA-based vaccine therapy. Driven by this practical clinical interest, a more detailed characterization of CTA biology has been recently undertaken. So far, at least 70 families of CTA, globally accounting for about 140 members, have been identified. Most of these CTA are expressed during spermatogenesis, but their function is still largely unknown. Epigenetic events, particularly DNA methylation, appear to be the primary mechanism regulating CTA expression in both normal and transformed cells, as well as in cancer stem cells. In view of the growing interest in CTA biology, the aim of this review is to provide the most recent information on their expression, regulation and function, together with a brief summary of the major clinical trials involving CTA as therapeutic agents. The pharmacologic modulation of CTA expression profiles on neoplastic cells by DNA hypomethylating drugs will also be discussed as a feasible approach to design new combination therapies potentially able to improve the clinical efficacy of currently adopted CTA-based immunotherapeutic regimens in cancer patients.

Dendritic cells in cancer immunotherapy

DC initiate and regulate T-cell immunity and are thus the key to optimization of all types of vaccines. Insights into DC biology offer many opportunities to enhance immunogenicity. In this Viewpoint, I discuss some recent developments and findings that are of immediate relevance for the clinical development of cancer vaccines. In addition, I emphasize my personal view that we should explore the potential of adoptively transferred DC (i.e. DC vaccination) as cancer vaccines by performing two-armed trials that address critical variables and by delivering antigens via mRNA-transfected DC.

Molecular profiling to identify relevant immune resistance mechanisms in the tumor microenvironment

The molecular identification of tumor antigens initially catalyzed substantial enthusiasm for the development of tumor antigen-based vaccines for the treatment of cancer. However, numerous vaccine approaches in melanoma and other cancers have yielded a low rate of clinical response, despite frequent induction of specific T cells as detected in the peripheral blood. This observation has prompted several investigators to begin interrogating the tumor microenvironment for biologic correlates to tumor response versus resistance. Evidence is beginning to emerge suggesting that distinct subsets of tumors may exist that reflect distinct categories of immune escape. Lack of chemokine-mediated trafficking, poor innate immune cell activation, and the presence of specific immune suppressive mechanisms can be found to characterize subsets of tumors. A non-inflamed tumor phenotype may predict for resistance to cancer vaccines, suggesting a possible predictive biomarker and patient enrichment strategy. But in addition, characterization of these subsets may pave the way for catering therapeutic interventions toward the biologic features of the tumor in individual patients.

Chemokines: can effector cells be redirected to the site of the tumor?

Chemokines (ie, chemoattractant cytokines) are a family of small secreted molecules that mediate leukocyte migration. It is becoming increasingly more evident that chemokines play an integral role in the initiation of a specific immune response. With respect to cancer, chemokines are being studied for both their role in tumor biology and as promising immunotherapy candidates. We review several areas of chemokine importance in tumor immunity and discuss the experimental evidence that is leading to the clinical use of this cytokine family in new treatment approaches for patients with cancer.

Gene signature in melanoma associated with clinical activity: a potential clue to unlock cancer immunotherapy

Immunotherapeutic approaches for melanoma and other cancers can impart profound clinical benefit but only for a subset of patients. Interpatient heterogeneity could, in principle, be due to somatic differences in the tumor between individuals or alternatively be accounted for distinct germline polymorphisms in immunoregulatory genes of the host. Analysis of these possibilities has been initiated by investigating gene expression profiling of the tumor microenvironment in the context of clinical trials of cancer vaccines. Distinct gene expression profiles have been identified on pretreatment biopsies that are associated with a positive or negative clinical outcome. These observations suggest that such profiling might be useful as a predictive biomarker for clinical benefit from vaccines and other immunotherapy approaches, and analysis of specific gene products has begun to suggest new therapeutic interventions to overcome mechanisms of tumor resistance.

Cancer vaccines: Where are we going?

Abstract The discovery that the immune system can distinguish molecular targets on cancer cells has led to efforts to develop cancer immunotherapeutics that can improve the recognition and effective elimination of tumor cells. Several types of tumor antigens are recognized by T lymphocytes, which are classified according to patterns of gene expression or protein distribution. Of particular interest is the group of molecules known as cancer-germline or cancer-testis antigens. As the relationship between the immune system and cancer has become clearer, so too have the challenges in designing effective cancer immunotherapeutics: (i) antigens need to be specifically selected based on ideal characteristics, such as tissue distribution that is restricted to tumors; (ii) selected antigens need to be combined with adjuvant agents that enhance their immunogenicity and yield robust responses; (iii) vaccination should be timed to pre-empt the development of regulatory suppressive immune mechanisms; and (iv) if suppressive regulatory mechanisms do arise, specific antagonists may be needed to enhance pro-immune outcomes. These challenges are shaping current and future research in this area.

Immunotherapy in the landscape of new targeted treatments for non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide. Active immunotherapies and molecules targeting tyrosine kinase receptors both offer new avenues for the treatment of NSCLC. Furthermore, their combinations or their administration along with standard treatments enlarges the potential for clinical benefit. Moreover, the discovery of biomarkers predicting the response to these new therapies should allow a better selection of patients susceptible to optimally benefit from these treatments. In this paper, we review the most promising active immunotherapies, antibodies and small molecules in the context of NSCLC management, focusing on compounds in phase III clinical development.

Therapeutic vaccines in solid tumours: can they be harmful?

Rosenberg and coworkers caused an uproar in the immunotherapy community when they stated in a position paper that despite great advances in the field of tumour immunology, optimism about the clinical application of therapeutic vaccines lacked justification. They argued that such optimism was based more on surrogate end-points, which lacked robustness, than on proof of anti-tumour effects [Rosenberg SA, Yang JC, Restifo NP. Cancer immunotherapy: moving beyond current vaccines. Nat Med 2004; 10:909-15]. They pointed out that cancer vaccine trials in 440 patients, conducted at the NCI Surgery Branch, had an overall objective response rate of only 2.6%. This was comparable to the 4.0% response rate reported in 40 studies that involved 756 patients. They concluded that surrogate end-points with such low response rates lack robustness. The situation may be even more problematic. Results of a number of larger trials in the past few years have indicated that vaccination therapy can also have a detrimental effect and be associated with worse outcome. These findings need to be looked at seriously and should lead to a critical appraisal of how well we understand these outcomes, how vaccine trials should be designed, monitored and conducted and which opportunities should be considered to be implemented in vaccine trial designs to improve the rationale and chances for a positive outcome.