Immunotherapy for bladder cancer

Similar immune responses to alpha1-oleate and Bacillus Calmette-Guérin treatment in patients with bladder cancer

BACKGROUND

The molecular content of urine is defined by filtration in the kidneys and by local release from tissues lining the urinary tract. Pathological processes and different therapies change the molecular composition of urine and a variety of markers have been analyzed in patients with bladder cancer. The response to BCG immunotherapy and chemotherapy has been extensively studied and elevated urine concentrations of IL-1RA, IFN-α, IFN-γ TNF-α, and IL-17 have been associated with improved outcome.

METHODS

In this study, the host response to intravesical alpha 1-oleate treatment was characterized in patients with non-muscle invasive bladder cancer by proteomic and transcriptomic analysis.

RESULTS

Proteomic profiling detected a significant increase in multiple cytokines in the treatment group compared to placebo. The innate immune response was strongly activated, including IL-1RA and pro-inflammatory cytokines in the IL-1 family (IL-1α, IL-1β, IL-33), chemokines (MIP-1α, IL-8), and interferons (IFN-α2, IFN-γ). Adaptive immune mediators included IL-12, Granzyme B, CD40, PD-L1, and IL-17D, suggesting broad effects of alpha 1-oleate treatment on the tumor tissues.

CONCLUSIONS

The cytokine response profile in alpha 1-oleate treated patients was similar to that reported in BCG treated patients, suggesting a significant overlap. A reduction in protein levels at the end of treatment coincided with inhibition of cancer-related gene expression in tissue biopsies, consistent with a positive treatment effect. Thus, in addition to killing tumor cells and inducing cell detachment, alpha 1-oleate is shown to activate a broad immune response with a protective potential.

BCG-Unresponsive Non-Muscle-Invasive Bladder Cancer: Current Treatment Landscape and Novel Emerging Molecular Targets

Urothelial carcinoma (UC), the sixth most common cancer in Western countries, includes upper tract urothelial carcinoma (UTUC) and bladder carcinoma (BC) as the most common cancers among UCs (90-95%). BC is the most common cancer and can be a highly heterogeneous disease, including both non-muscle-invasive (NMIBC) and muscle-invasive (MIBC) forms with different oncologic outcomes. Approximately 80% of new BC diagnoses are classified as NMIBC after the initial transurethral resection of the bladder tumor (TURBt). In this setting, intravesical instillation of Bacillus Calmette-Guerin (BCG) is the current standard treatment for intermediate- and high-risk patients. Unfortunately, recurrence occurs in 30% to 40% of patients despite adequate BCG treatment. Radical cystectomy (RC) is currently considered the standard treatment for NMIBC that does not respond to BCG. However, RC is a complex surgical procedure with a recognized high perioperative morbidity that is dependent on the patient, disease behaviors, and surgical factors and is associated with a significant impact on quality of life. Therefore, there is an unmet clinical need for alternative bladder-preserving treatments for patients who desire a bladder-sparing approach or are too frail for major surgery. In this review, we aim to present the strategies in BCG-unresponsive NMIBC, focusing on novel molecular therapeutic targets.

From Interferon to Checkpoint Inhibition Therapy-A Systematic Review of New Immune-Modulating Agents in Bacillus Calmette-Guérin (BCG) Refractory Non-Muscle-Invasive Bladder Cancer (NMIBC)

BACKGROUND

In Bacillus Calmette-Guérin (BCG) refractory non-muscle-invasive bladder cancer (NMIBC), radical cystectomy is the gold standard. The advent of immune checkpoint inhibitors (CPIs) has permanently changed the therapy landscape of bladder cancer (BC). This article presents a systematic review of immune-modulating (IM) therapies (CPIs and others) in BCG-refractory NMIBC.

METHODS

In total, 406 articles were identified through data bank research in PubMed/Medline, with data cutoff in October 2021. Four full-text articles and four additional congress abstracts were included in the review.

RESULTS

Durvalumab plus Oportuzumab monatox, Pembrolizumab, and Nadofaragene firadenovec (NF) show complete response (CR) rates of 41.6%, 40.6%, and 59.6% after 3 months, with a long-lasting effect, especially for NF (12-month CR rate of 30.5%). Instillations with oncolytic viruses such as NF and CG0070 show good efficacy without triggering significant immune-mediated systemic adverse events. Recombinant BCG VPM1002BC could prove to be valid as an alternative to BCG in the future. The recombinant pox-viral vector vaccine PANVAC™ is not convincing in combination with BCG. Interleukin mediating therapies, such as ALT-803, are currently being studied.

CONCLUSION

CPIs and other IM agents now offer an increasing opportunity for bladder-preserving strategies. Studies on different substances are ongoing and will yield new findings.

Dual Nature of Relationship between Mycobacteria and Cancer

Although the therapeutic effect of mycobacteria as antitumor agents has been known for decades, recent epidemiological and experimental studies have revealed that mycobacterium-related chronic inflammation may be a possible mechanism of cancer pathogenesis. Mycobacterium tuberculosis and non-tuberculous Mycobacterium avium complex infections have been implicated as potentially contributing to the etiology of lung cancer, whereas Mycobacterium ulcerans has been correlated with skin carcinogenesis. The risk of tumor development with chronic mycobacterial infections is thought to be a result of many host effector mechanisms acting at different stages of oncogenesis. In this paper, we focus on the nature of the relationship between mycobacteria and cancer, describing the clinical significance of mycobacteria-based cancer therapy as well as epidemiological evidence on the contribution of chronic mycobacterial infections to the increased lung cancer risk.

Cancer Immunotherapy: Priming the Host Immune Response with Live Attenuated Salmonella enterica

In recent years, cancer immunotherapy has undergone great advances because of our understanding of the immune response and the mechanisms through which tumor cells evade it. A century after the first immunotherapy attempt based on bacterial products described by William Coley, the use of live attenuated bacterial vectors has become a promising alternative in the fight against cancer. This review describes the role of live attenuated Salmonella enterica as an oncolytic and immunotherapeutic agent, due to its high affinity for tumor tissue and its ability to activate innate and adaptive antitumor immune response. Furthermore, its potential use as delivery system of tumor antigens and immunomodulatory molecules that induce tumor regression is also reviewed.

Management of Hepatic Granulomatous Tuberculosis After BCG Therapy for Bladder Cancer

BCG therapy is used as a treatment in bladder cancer. Intravesical administration of Bacillus Calmette-Guérin is used as a treatment method in superficial bladder cancer. While it is commonly effective, some serious side effects may occur. We hereby report a 65-year-old man who developed granulomatous hepatitis as a complication following BCG therapy. He was treated successfully with antitubercular therapy and prednisolone.

Innate signaling by mycobacterial cell wall components and relevance for development of adjuvants for subunit vaccines

INTRODUCTION

Pathogen recognition receptors (PRRs) recognize pathogen-associated molecular patterns, triggering the induction of inflammatory innate responses and contributing to the development of specific adaptive immune responses. Novel adjuvants have been developed based on agonists of PRRs. Areas covered: Lipid pathogen-associated molecular patterns (PAMPs) present in the cell wall of mycobacteria are revised, with emphasis on agonists of C-type lectin receptors, signaling pathways, and preclinical data supporting their use as novel adjuvants inducing cell-mediated immune responses. Their potential use as lipid antigens in novel tuberculosis subunit vaccines is also discussed. Expert commentary: Few adjuvants are licensed for human use and mainly favour antibody-mediated protective immunity. Use of lipid PAMPs that trigger cell-mediated immune responses could lead to the development of adjuvants for vaccines against intracellular pathogens and cancer.

Intravesical and alternative bladder-preservation therapies in the management of non-muscle-invasive bladder cancer unresponsive to bacillus Calmette-Guérin

Intravesical Bacillus Calmette-Guérin (BCG) remains the standard of care in the treatment of bladder carcinoma in situ and as adjuvant therapy after thorough transurethral resection of high-grade non-muscle-invasive bladder cancer. Despite BCG therapy, in up to 40% of patients it would recur and 60% to 70% of those would fail repeat BCG induction be deemed BCG unresponsive. For such patients, cystectomy remains the preferred treatment option per the American Urological Association and European Association of Urology, though some patients would be medically unfit or refuse radical surgery. Further intravesical therapy for bladder-preservation therapies may preserve quality of life in these patients and in some cases can be curative. There are numerous non-BCG intravesical salvage options available, including immunotherapy, single-agent chemotherapy, combination chemotherapy, and device-assisted chemotherapy. In addition, investigation of radiation-based treatment and other novel therapies including checkpoint inhibitors (programmed death-1/programmed death ligand-1), are currently underway. In this review, we examine the current status of alternatives to BCG in salvage therapy for bladder preservation.

Dendritic cell cancer vaccines: from the bench to the bedside

The recognition that the development of cancer is associated with acquired immunodeficiency, mostly against cancer cells themselves, and understanding pathways inducing this immunosuppression, has led to a tremendous development of new immunological approaches, both vaccines and drugs, which overcome this inhibition. Both "passive" (e.g. strategies relying on the administration of specific T cells) and "active" vaccines (e.g. peptide-directed or whole-cell vaccines) have become attractive immunological approaches, inducing cell death by targeting tumor-associated antigens. Whereas peptide-targeted vaccines are usually directed against a single antigen, whole-cell vaccines (e.g. dendritic cell vaccines) are aimed to induce robust responsiveness by targeting several tumor-related antigens simultaneously. The combination of vaccines with new immuno-stimulating agents which target "immunosuppressive checkpoints" (anti-CTLA-4, PD-1, etc.) is likely to improve and maintain immune response induced by vaccination.

Complications of intravesical bacillus calmette-guérin

Intravesical Bacillus Calmette-Guérin (BCG) is an important treatment for the management of non-muscle invasive bladder cancer because of its proven efficacy and favourable safety profile. The most common complications associated with BCG treatment are relatively minor. They include urinary frequency, cystitis, fever, and hematuria. Although serious complications are rare, patients can develop severe, life-threatening sepsis with disseminated mycobacterial infection. We report a rare case of periurethral diverticulum formation after intravesical BCG and review the literature on the potential complications of this treatment modality.

Regulation of immunotherapeutic products for cancer and FDA's role in product development and clinical evaluation

Immunotherapeutics include drugs and biologics that render therapeutic benefit by harnessing the power of the immune system. The promise of immune-mediated therapies is target specificity with a consequent reduction in off-target side effects. Recent scientific advances have led to clinical trials of both active and passive immunotherapeutic products that have the potential to convert life-ending diseases into chronic but manageable conditions. Clinical trials investigating immunotherapeutics are ongoing with some trials at advanced stages of development. However, as with many products involving novel mechanisms of action, major regulatory and scientific issues arising with clinical use of immunotherapeutic products remain to be addressed. In this review, we address issues related to different immunotherapeutics and provide recommendations for the characterization and evaluation of these products during various stages of product and clinical development.

Bladder Cancer Immunotherapy: BCG and Beyond

Mycobacterium bovis bacillus Calmette-Guérin (BCG) has become the predominant conservative treatment for nonmuscle invasive bladder cancer. Its mechanism of action continues to be defined but has been shown to involve a T helper type 1 (Th1) immunomodulatory response. While BCG treatment is the current standard of care, a significant proportion of patients fails or do not tolerate treatment. Therefore, many efforts have been made to identify other intravesical and immunomodulating therapeutics to use alone or in conjunction with BCG. This paper reviews the progress of basic science and clinical experience with several immunotherapeutic agents including IFN-α, IL-2, IL-12, and IL-10.

Use of fluorescence in situ hybridization to predict response to bacillus Calmette-Guérin therapy for bladder cancer: results of a prospective trial

PURPOSE

No reliable methods currently exist to predict patient response to intravesical immunotherapy with bacillus Calmette-Guérin given after transurethral resection for high risk nonmuscle invasive bladder cancer. We initiated a prospective clinical trial to determine whether fluorescence in situ hybridization results during bacillus Calmette-Guérin immunotherapy can predict therapy failure.

MATERIALS AND METHODS

Candidates for standard of care bacillus Calmette-Guérin were offered participation in a clinical trial. Fluorescence in situ hybridization was performed before bacillus Calmette-Guérin, and at 6 weeks, 3 months and 6 months during bacillus Calmette-Guérin therapy with maintenance. Cox proportional hazards regression was used to assess the relationship between fluorescence in situ hybridization results and tumor recurrence or progression. The Kaplan-Meier product limit method was used to estimate recurrence-free and progression-free survival.

RESULTS

A total of 126 patients participated in the study. At a median followup of 24 months 31% of patients had recurrent tumors and 14% experienced disease progression. Patients who had positive fluorescence in situ hybridization results during bacillus Calmette-Guérin therapy were 3 to 5 times more likely than those who had negative fluorescence in situ hybridization results to experience recurrent tumors and 5 to 13 times more likely to have disease progression (p <0.01). The timing of positive fluorescence in situ hybridization results also affected outcomes. For example, patients with a negative fluorescence in situ hybridization result at baseline, 6 weeks and 3 months demonstrated an 8.3% recurrence rate compared to 48.1% for those with a positive result at all 3 points.

CONCLUSIONS

Fluorescence in situ hybridization results can identify patients at risk for tumor recurrence and progression during bacillus Calmette-Guérin immunotherapy. This information may be used to counsel patients about alternative treatment strategies.

The antidiabetic drug ciglitazone induces high grade bladder cancer cells apoptosis through the up-regulation of TRAIL

BACKGROUND

Ciglitazone belongs to the thiazolidinediones class of antidiabetic drug family and is a high-affinity ligand for the Peroxisome Proliferator-Activated Receptor γ (PPARγ). Apart from its antidiabetic activity, this molecule shows antineoplastic effectiveness in numerous cancer cell lines.

METHODOLOGY/PRINCIPAL FINDINGS

Using RT4 (derived from a well differentiated grade I papillary tumor) and T24 (derived from an undifferentiated grade III carcinoma) bladder cancer cells, we investigated the potential of ciglitazone to induce apoptotic cell death and characterized the molecular mechanisms involved. In RT4 cells, the drug induced G2/M cell cycle arrest characterized by an overexpression of p53, p21(waf1/CIP1) and p27(Kip1) in concomitance with a decrease of cyclin B1. On the contrary, in T24 cells, it triggered apoptosis via extrinsic and intrinsic pathways. Cell cycle arrest and induction of apoptosis occurred at high concentrations through PPARγ activation-independent pathways. We show that in vivo treatment of nude mice by ciglitazone inhibits high grade bladder cancer xenograft development. We identified a novel mechanism by which ciglitazone kills cancer cells. Ciglitazone up-regulated soluble and membrane-bound TRAIL and let TRAIL-resistant T24 cells to respond to TRAIL through caspase activation, death receptor signalling pathway and Bid cleavage. We provided evidence that TRAIL-induced apoptosis is partially driven by ciglitazone-mediated down-regulation of c-FLIP and survivin protein levels through a proteasome-dependent degradation mechanism.

CONCLUSIONS/SIGNIFICANCE

Therefore, ciglitazone could be clinically relevant as chemopreventive or therapeutic agent for the treatment of TRAIL-refractory high grade urothelial cancers.

Management of hepatic granulomatous tuberculosis complicating intravesical BCG for superficial bladder cancer

Intravesical bacille Calmette-Guérin (BCG) therapy is the most effective treatment for high-risk superficial bladder cancer. Severe systemic complications are rare, but may occur in approximately 1% of cases. We report a severe complication of intravesical BCG: a disseminated Mycobacterium bovis infection with biopsy-proven granulomatous hepatitis in a patient with bladder cancer. We also elaborate on the different management alternatives.

Multi-organ failure with atypical liver granulomas following intravesical Bacillus Calmette-Guerin instillation

Bacillus Calmette-Guerin (BCG) intravesical instillation has been adopted in the treatment of patients with superficial bladder cancer. BCG-induced disseminated infection, though rare, has been associated with the histological finding of epithelioid granulomas in different organs, including the liver. We report the case of an adult patient with multi-organ failure, who developed sepsis, acute respiratory failure and acute hepatic failure with encephalopathy whose liver biopsy confirmed the presence of atypical, granulomatous-like lesions. Recovery was observed only after empirical therapy for Mycobacterium bovis with isoniazid, rifampicin, ethambutol and steroids was introduced. This case highlights the importance of a thorough patient assessment in order to exclude other more common causes of hepatic granulomas and to confirm diagnosis. Histological findings may be non-specific when the liver is involved in BCG-induced disseminated infection.

The molecular, the bad, and the ugly: preventing bladder cancer via mTOR inhibition

This perspective on Seager et al. (beginning on p. 1008) considers an important advance in the effort to control bladder cancer. Frontline therapy for superficial transitional cell carcinoma of the bladder involves instillation of the crude immunomodulatory bacterial extract Bacillus Calmette-Guérin directly into the organ. Seager et al. now show that local administration of a chemical inhibitor of mammalian target of rapamycin strongly suppressed growth in a novel preclinical mouse model that develops carcinoma in situ, a particularly problematic form of transitional cell carcinoma of the bladder. The results not only support the clinical evaluation of mammalian target of rapamycin inhibitors in this setting, they open the door for the evaluation of additional molecular local therapies as well.

Combination therapy with IFN-alpha plus bortezomib induces apoptosis and inhibits angiogenesis in human bladder cancer cells

In a recent study, we showed that the proteasome inhibitor bortezomib sensitizes human bladder cancer cells to IFN-induced cell death. Here, we characterized the molecular mechanisms underlying the antitumoral effects of the combination in more detail. Bortezomib synergized with IFN-alpha to promote apoptosis via a tumor necrosis factor-related apoptosis-inducing ligand-associated mechanism but did not inhibit production of proangiogenic factors (vascular endothelial growth factor, basic fibroblast growth factor, and interleukin-8) in human UM-UC-5 cells. In contrast, exposure to the combination did not increase the levels of apoptosis in human UM-UC-3 cells but did inhibit the production of basic fibroblast growth factor and vascular endothelial growth factor. Studies with tumor xenografts confirmed that combination therapy with bortezomib plus IFN-alpha was effective in both models but that the effects were associated with differential effects on tumor necrosis factor-related apoptosis-inducing ligand-associated apoptosis (predominant in UM-UC-5) versus inhibition of angiogenesis (predominant in UM-UC-3). Together, our results show that combination therapy with IFN-alpha plus bortezomib is effective but can work via different mechanisms (apoptosis versus angiogenesis inhibition) in preclinical models of human bladder cancer.

Antisense oligonucleotides in the treatment of bladder cancer

This review examines the role that antisense oligonucleotides play in the treatment of superficial and muscle-invasive bladder cancer. The unique environment of the urinary bladder allows intravesical instillation of antisense oligonucleotides, and researchers have already demonstrated uptake of antisense oligonucleotides in models of bladder cancer. Second, proof of principle has been established by demonstrating downregulation of the antisense target mRNA and protein. Third, and most importantly from a therapeutic perspective, synergy between chemotherapy and antisense oligonucleotides has been shown in bladder cancer models in vitro and in vivo. The collective evidence points to a role for antisense oligonucleotides in the treatment of superficial and muscle-invasive bladder cancer in combination with existing treatment modalities.

Role of Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand in Interferon-Induced Apoptosis in Human Bladder Cancer Cells

Immunomodulators such as Bacillus Calmette-Guerin and interferon are clinically active in transitional cell carcinoma of the bladder, but their mechanisms of action remain unclear. Here we investigated the effects of IFNalpha on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) expression and apoptosis in a panel of 20 human bladder cancer cell lines. Six (30%) displayed significant DNA fragmentation in response to increasing concentrations of IFNalpha (10-100,000 units/mL). In these lines IFNalpha induced early activation of caspase-8, and DNA fragmentation was blocked by a caspase-8-selective inhibitor (IETDfmk), consistent with the involvement of death receptor(s) in cell death. IFNalpha stimulated marked increases in TRAIL mRNA and protein in the majority of IFN-sensitive and IFN-resistant cell lines. A blocking anti-TRAIL antibody significantly inhibited IFN-induced DNA fragmentation in four of six IFN-sensitive cell lines, confirming that TRAIL played a direct role in cell death. Bortezomib (PS-341, Velcade), a potent TRAIL-sensitizing agent, increased sensitivity to IFNalpha in two of the IFN-resistant cell lines that produced large amounts of TRAIL in response to IFN treatment. Our data show that IFN-induced apoptosis in bladder cancer cells frequently involves autocrine TRAIL production. Combination therapy strategies aimed at overcoming TRAIL resistance may be very effective in restoring IFN sensitivity in a subset of human bladder tumors.

A novel Gal(beta1-4)Gal(beta1-4)Fuc(alpha1-6)-core modification attached to the proximal N-acetylglucosamine of keyhole limpet haemocyanin (KLH) N-glycans

KLH (keyhole limpet haemocyanin), the oxygen-carrying molecule of the marine snail Megathura crenulata, is often used as an adjuvant or as a hapten carrier for immunizations with peptides, oligosaccharides or other low-molecular-mass organic compounds. KLH exhibits several carbohydrate determinants, at least some of which are immunogenic: it shares an antigenic Fuc(alpha1-3)GalNAc-determinant with schistosomes and contains unique Gal-(beta1-6)Man-structural motifs on its N-glycans. This study reveals the presence of N-glycans with unusual +/-Gal(beta1-4)Gal(beta1-4)Fuc- units (alpha1-6)-linked to the reducing end N -acetylglucosamine residue. The following novel structures of KLH N-glycans were deduced by linkage analysis, exoglycosidase digestion, matrix-assisted laser-desorption ionization-tandem MS and nano-LC-ESI-IT-MS (where LC stands for liquid chromatography, ESI for electrospray ionization and IT for ion trap): Man(alpha1-6)[+/-Man(alpha1-3)]Man(beta1-4)GlcNAc(beta1-4)[Gal(beta1-4)Fuc(alpha1-6)]GlcNAc and Man(alpha1-6)Man(beta1-4)GlcNAc(beta1-4)[Gal(beta1-4)Gal(beta1-4)Fuc(alpha1-6)]GlcNAc. The Gal(beta1-4)Fuc- and Gal(beta1-4)Gal(beta1-4)Fuc- core modifications are expected to be immunogenic, similar to other non-mammalian-type core modifications, and to contribute to the immunostimulatory properties of KLH.

Therapeutic approaches to bladder cancer: identifying targets and mechanisms

Transitional cell carcinoma is the second most common genitourinary malignancy in US and third most common cause of death among genitourinary tumors. Treatment options for bladder cancer include surgery, often combined with chemotherapy, radiation, and/or immunotherapy. The MVAC adjuvant chemotherapy regimen has been most widely used in locally invasive as well as metastatic disease. Only a proportion of patients at risk will respond to therapy. There is thus need to identify good responder patients for adjuvant therapy and to identify new targets to treat a greater range of patients. Based upon patient-specific aberrations in pathways or known markers, both existing and new therapies can be tailored to benefit patients based on the risk of progression and molecular alterations specific to a patient's tumor. Targeted therapy, therefore, is defined as therapy that targets mechanism and risk. Utilizing the available knowledge of the molecular biology of cell-cycle regulation, signal transduction, apoptosis, and angiogenesis in bladder cancer, we review the potential therapeutic targets for rational drug development. Finally, using bladder cancer as a model for translational research, requirements for a desired clinical trial are presented.

Cytotoxic lymphocytes primed by DC based hepatocellular carcinoma vaccine against growth of carcinoma xenograft on nude mice

AIM

To investigate the cytotoxic lymphocyte (CTL) primed by DC based hepatocellular carcinoma (HCC) vaccine against the growth of the carcinoma xenograft on nude mice.

METHODS

High purity of dendritic cells (DCs) were obtained and the immune responses of lymphocytes primed by BCG HSP70 activated DCs were loaded with HCC associated antigens to prepare DC based HCC vaccine. The nude mouse model bearing human HCC xenografts was established and the characteristics of the tumor were identified with immunohistochemical techniques. Transplanted human HCC on nude mouse was treated with freezing and anabiotic HCC specific lymphocytes.

RESULTS

Lymphocytes primed by DCs based HC vaccine had the specific cytotoxicity against HCC lines. The CTL after freezing and anabiotics could prevent and treat HCC xenograft on nude mice with a preventive rate of 97 %.

CONCLUSION

DCs not only inhibit the growth of human HCC and other cancer cells in vitro, but also prevent the growth of HCC xenograft on nude mice in vivo.

Cancer immunotherapy: the past, the present and the future

One of the most controversial issues in immunology for over a century has been whether an effective immune response can be elicited against malignant tumours. Whether the immunology community has believed cancer immunotherapy is feasible or impossible has been largely determined by the prevailing immunological paradigms at that time. In fact, during the last 110 years it is possible to trace at least five dramatic fluctuations in attitude towards cancer immunotherapy. It now appears, however, that overwhelming evidence is available to support the view that both the innate and adaptive immune responses can recognize and eliminate tumours. On the other hand, it remains to be seen if these immune responses can be harnessed to control cancer as, at the time of diagnosis, many tumours have already been immunoselected to be highly resistant to immune elimination. Based on these observations it is argued that immunotherapy approaches, other than the generation of tumour-specific cytotoxic T lymphocytes, must be explored. Alternative strategies include recruiting tumouricidal myeloid cells into tumours, generating antiangiogenic immune responses and directing innate immunity to hypoxia-induced ligands on tumour cells.