Harnessing the to combat cancer W. Joost Lesterhuis and Cornelis J. A. Punt Efforts to harness the immune system to treat cancer date back more than a century, Examples of anticancer therapeutics in both broad categories — such as the immune but progress was slow for decades. However, the recent clinical success of several checkpoint inhibitor and the therapeutic vaccine sipuleucel-T — have anticancer immunotherapies has provided a boost to the field. Approaches to induce recently received regulatory approval, and several other agents are in clinical trials an antitumour immune response (see centre image) can be broadly subdivided into (see table). Such trials are faced with challenges such as selection of optimal methods DRUG non--specific or antigen-specific categories. Non-antigen-specific strategies of evaluation, as those developed for typical anticancer chemotherapies may not be include nonspecific immune stimulation and inhibition of ‘immune checkpoint’ well suited to immunotherapies. Nevertheless, recent encouraging clinical results, interactions, whereas antigen-specific strategies include adoptive cell transfer of as well as the unexpected finding of a positive interaction between immunotherapy DISCOVERY autologous cancer-specific T cells and various therapeutic vaccination approaches. and chemotherapy, may herald a new era for anticancer immunotherapy.

Examples of experimental and approved anticancer immunotherapies* Adjuvants: Nonspecific immune stimulation Immune checkpoint blockade APC/tumour cell Drug (companies) Formulation Tumour type Current phase Cytokines: • TLR ligands T cell Antigen of development Nonspecific immune stimulation can be achieved with agents that stimulate immune Several immune-inhibiting mechanisms that normally prevent • IFNα • CD40 ligand MHC Immune checkpoint blockade effector cells such as T cells and APCs (for example, DCs), or inhibit and/or deplete collateral damage to tissues from an ongoing immune response can • IL-2 • BCG TCR Ipilimumab CTLA4-blocking Melanoma Approved immunoregulatory cells such as TReg cells. Effector T cells can be stimulated with also help cancer cells evade the immune system. The figure shows (Bristol-Myers Squibb) TLR Prostate cancer Phase III cytokines such as IL-2 and IFNα, which are both approved for the treatment of melanoma the interaction between a T cell and an APC or tumour cell, and NSCLC CD40 and . Durable complete remissions after IL-2 treatment of melanoma The induction of antitumour immunity detailing receptor interactions that downmodulate the activation Other tumours Phase I–II patients have been observed in selected patients. However, given the need for prolonged of T cells that recognize antigen presented on MHC molecules. T cell Early co- CTLA4 B7 Tremelimumab (Pfizer) CTLA4-blocking antibody Melanoma Phase III use and associated toxicity of these cytokines, they are not commonly used. Approaches Blocking such immune checkpoints results in enhanced, nonspecific inhibitory Properly activated and non- Other tumours Phase I–II MHC that aim to provide full APC activation use adjuvants such as TLR ligands. The TLR7 T cell activation and/or T cell survival. CTLA4–B7 interactions are signals CTLA4 B7 T cell inhibited CTLs recognize agonist imiquimod is approved for the treatment of basal cell carcinoma. The adjuvant tumour-associated important during the induction phase of the T cell response, MDX‑1106 (Medarex/ PD1-blocking antibody Melanoma, RCC Phase II TCR DC Bristol-Myers Squibb) and NSCLC BCG has been approved as a standard therapy for local instillation in bladder cancer. and kill tumour cells whereas PD1–PDL1 interactions seem to have the most prominent Antibody-based approaches targeting the co-stimulatory receptor CD40 are in role during the effector phase of the T cell response. The CTLA4- Late co- PD1 PDL1 CT‑011 (CureTech) PD1-blocking antibody Melanoma and Phase II development. T cells can be depleted by targeting the IL-2 receptor with the anti- blocking antibody ipilimumab has recently been approved for inhibitory haematological TReg cell Reg signals malignancies CD25 (IL-2 receptor α-chain) antibody daclizumab, the recombinant IL-2–diphtheria treating patients with metastatic melanoma. Clinical trials that PD1 PDL1 MK‑3475 (Merck) PD1-blocking antibody Solid tumours Phase I IL-2 receptor toxin conjugate denileukin diftitox or low-dose treatment with the chemotherapeutic investigate targeting other immune checkpoint Tumour AMP‑224 PDL2–IgG1 fusion protein Solid tumours Phase I cyclophosphamide. However, the lack of specificity of these approaches poses a Tumour cells express molecules such as PD1 or PDL1 are underway. Immune checkpoint- Supplement to Nature Publishing Group Journals cell (Amplimmune/ Antibody significant challenge. Other cytotoxic chemotherapeutics and targeted anticancer drugs tumour-associated blocking approaches are not patient-tailored, which makes them GlaxoSmithKline) can have immune-stimulating effects by inducing immunogenic cell death, depleting antigens in MHC class I less laborious and potentially less costly than cellular vaccines or Adoptive cell transfer Cyclophosphamide suppressive immune cells, disrupting inhibitory pathways or sensitizing tumour cells to adoptive cell transfer. However, the lack of specificity of immune Adoptive transfer with Polyclonal T cells against Melanoma Phase II T cell-induced cell death. Novel innovative treatment schedules that fully exploit the activation means there is a risk of autoimmune side effects. T cell TILs multiple tumour-associated immunogenic properties of these drugs need to be further developed. MDSC Reg antigens Adoptive transfer with Monoclonal T cells with Melanoma Phase I TCR-transduced T cells high-affinity TCR against single tumour-associated Autologous Genetically engineered Suppressive cells in the Protein/ Plasmid antigens tumour microenvironment Apoptotic peptide DNA Vaccination strategies inhibit immune activation tumour TIL Idiotype Sipuleucel-T Autologous APC vaccine Prostate cancer Approved (M2 macrophages, cell Vaccination strategies Virus antibody (Dendreon) loaded with prostate acid Tumour cell T cells and MDSCs) phosphatase T cells isolated Reg The goal of immunotherapeutic vaccination approaches is to ‘re-educate’ endogenous T cells by presenting the tumour DC-based vaccines Autologous DCs loaded with All cancer types Phase I–III Viral vector from blood tumour antigens antigen in the context of appropriate APC activation stimuli. Tumour MAGE‑3 ASCI MAGE‑3 protein NSCLC Phase III Tumour antigens can be administered in the form of synthetic (GlaxoSmithKline) surgically T cell proteins or peptides, or encoded by a plasmid DNA or virus. resected Adoptive cell transfer PROSTVAC (Bavarian Poxvirus-based Prostate cancer Phase III Viral vectors can also have direct oncolytic activity. For some Nordic) PSA-targeted vaccine Antigen-specific effector cells can be taken out of the B cell malignancies, idiotype antibodies have been explored OncoVEX (BioVex) Attenuated herpes simplex Melanoma and Phase III Retroviral insertion patient, selected and expanded ex vivo, and then as tumour-specific vaccines. An alternative approach that Adjuvant type 1 virus encoding human HNSCC of TCR gene re-infused into the patient, obviating the need to provide does not require the identification of tumour-specific Dissect GM‑CSF antigens or activate APCs. Two main approaches are being DC antigens is the use of extracted, irradiated tumour cells Irradiate tumour cells Idiotype antibodies Patient-specific Follicular Phase III explored. In the first approach, T cells that reside in the that are re-administered to the patient. For all of the above, tumour-derived idiotype lymphoma TILs isolated, antibody plus GM‑CSF tumour are cultured from tumour resection specimens adjuvants such as TLR agonists or GM-CSF are required. selected, (mainly explored for melanoma) and expanded ex vivo in the Melanocyte protein gp100 peptide vaccine Melanoma Phase III infused with Alternatively, APCs can be extracted from a patient’s Monocyte presence of IL-2. When enough of these polyclonal T cells are PMEL in Montanide adjuvant IL-2 and bloodstream, cultured and activated with cytokines or Tumour cell combined with IL‑2 Genetically DCs take up and process Mature grown to obtained, they are re-infused into the patient. This strategy adjuvants, loaded with antigen ex vivo, and re-administered vaccination engineered cells antigen from dead or dying DC Nonspecific immune stimulation large numbers was improved by combining it with a non-myeloablative to the patient. The antigens can be selected well-known APC grown to tumour cells, present the Tumour IL‑2 (Novartis/ Recombinant human IL‑2 Melanoma and Approved for preconditioning chemotherapy regime. In selected melanoma tumour antigens or derived from whole-tumour cells. large numbers tumour-associated antigens on antigen APC Prometheus) RCC melanoma in patients encouraging durable complete responses were The former strategy was followed for the development MHC class I and II, and provide vaccination some and for achieved and randomized multicentre trials are being initiated. of sipuleucel-T for the treatment of prostate cancer. Tumour RCC in most co-stimulatory signals for (sipuleucel-T) countries However, at present it is only possible to obtain enough T cells T cells and other immune cells Alternatively, DCs (the professional APCs of the immune antigen in a minority of patients. The second strategy uses isolated system) can be cultured from peripheral blood monocytes IFNα (Schering-Plough/ Recombinant human IFNα Melanoma and Approved for peripheral blood T cells that are genetically engineered to Hoffmann-La Roche) RCC melanoma in the presence of IL-4 and GM-CSF, and activated and DC (adjuvant) and Transfer into patient after express tumour-antigen-specific TCRs and then re-administered loaded with antigen ex vivo. Tailor-made vaccination vaccination RCC in several non-myeloablative to the patient. This strategy has the advantage that enough approaches require complex production processes that Activation countries preconditioning T cells can be obtained for infusion in all patients, but a are associated with substantial costs, and so far it has stimuli Immature DC Cyclophosphamide Low-dose preferentially Several cancer Phase I–II deplets T cells types lymphodepletion potential drawback is that the TCRs that are transfected into been challenging to achieve durable complete responses. Reg the T cells have a limited antigen-specificity repertoire. Daclizumab Anti-CD25 (IL-2 receptor Several cancer Phase I–II (Hoffman-La Roche) α‑chain) antibody types Denileukin diftitox Recombinant IL‑2– Several cancer Phase I–II Hypothesis of cancer First report of Discovery of MHC-I-restricted (1991, 1994) Characterization Rediscovery of Non-myeloablative HPV (Eisai) diphtheria toxin conjugate types 'immunosurveillance' allogeneic bone CD8+ T cell recognition by of human tumour-associated the T cell by chemotherapies and adoptive vaccination CP‑870893 (Pfizer) CD40 agonist monoclonal Solid tumours Phase I First study Reg antibody by Burnet marrow transplantation Zinkernagel and Doherty with IL-2 antigens by Rosenberg and Boon Sakaguchi T cell transfer in melanoma in VIN Imiquimod (Meda/ TLR7 agonist Basal cell Approved Graceway/iNova) carcinoma, VIN for basal cell and CIN carcinoma; in Phase III for VIN and CIN Resiquimod (Medicis TLR7 agonist alone or in Melanoma and Phase I 1898 1957 1973 1974 1976 1983 1985 1991 1992 1995 1996 2002 2008 2009 2010 Global Services combination with vaccines T cell lymphoma Corporation) CPG 7909 (Pfizer) TLR9 agonist Melanoma Phase II BCG Intravesical administration Urothelial cancer Approved of BCG as adjuvant Treatment of cancer Discovery of the Discovery of First study with First study First study with First study of isolated (1996, 1997, 2000) Discovery Imiquimod FDA approval of sipuleucel-T ‘Immunogenic’ Classic chemotherapeutics Several cancer Approved chemotherapy and types drugs but with bacterial dendritic cell by cross-presentation BCG in bladder with IFNα in adoptive cell limb perfusion with TNF of the immunological function used to in prostate cancer and targeted agents immunogenic products by Coley Steinman by Bevan cancer melanoma transfer in cancer in melanoma and sarcoma of TLRs treat VIN ipilimumab in melanoma potential not fully explored *References for approved drugs are included under further reading.

Bavarian Nordic A/S Dendreon Abbreviations Further Reading Affiliations Bavarian Nordic A/S is a vaccine-focused biotechnology company developing and Dendreon is a biotechnology company whose mission is to target cancer and transform APC, antigen-presenting cell; BCG, bacille Calmette–Guérin; CIN, cervical intraepithelial Dunne, A., Marshall, N. A. & Mills, K. H. Curr. Opin. Pharmacol. 11, 404–411 (2011). W. Joost Lesterhuis is at the Department of Medical Oncology, Radboud University producing novel vaccines for the treatment and prevention of life-threatening diseases lives through the discovery, development, commercialization and manufacturing of novel neoplasia; CTL, cytotoxic T lymphocyte; CTLA4, cytotoxic T lymphocyte antigen 4; Figdor, C. G. et al. Nature Med. 10, 475–480 (2004). Nijmegen Medical Centre, P.O. Box 9101, 6500HB Nijmegen, The Netherlands. with a large unmet medical need. The company’s pipeline targets cancer and infectious therapeutics. The company applies its expertise in antigen identification, engineering and DC, dendritic cell; GM-CSF, granulocyte–macrophage colony-stimulating factor; Jacobs, J. F. et al. Lancet Oncol. 13, e32–e42 (2012). Cornelis J. A. Punt is at the Department of Medical Oncology, Academic Medical Center, Kantoff, P. W. et al. N. Engl. J. Med. 363, 411–422 (2010). HNSCC, head and neck squamous cell carcinoma; HPV, human papilloma virus; University of Amsterdam, P.O. Box 22660, 1100 DD Amsterdam, The Netherlands. diseases, and includes ten development programs. The oncology pipeline is developed cell processing to produce active cellular immunotherapy (ACI) product candidates Lesterhuis, W. J., Haanen, J. B. & Punt, C. J. Nature Rev. Drug Discov. 10, 591–600 (2011). IFNα, interferon-α; IL-2, interleukin-2; MAGE-3, melanoma-associated antigen 3; through the subsidiary BN ImmunoTherapeutics, located in Mountain View, California. designed to stimulate an immune response in a variety of tumor types. Dendreon’s first Robert, C. et al. N. Engl. J. Med. 364, 2517–2526 (2011). MDSC, myeloid-derived suppressor cell; NSCLC, non-small-cell lung cancer; Designed by Susie Lanni & Susanne Harris. The company’s lead program is PROSTVAC®, a therapeutic vaccine candidate for product, PROVENGE® (sipuleucel-T), was approved by the U.S. Food and Drug Rosenberg, S. A. Nature Rev. Clin. Oncol. 10, 577–585 (2011). PD1, programmed cell death protein 1; PDL1, PD1 ligand 1; PSA, prostate-specific antigen; Edited by Alexandra Flemming. treatment of advanced prostate cancer that is the subject of an ongoing pivotal Phase 3 Administration (FDA) in April 2010. Dendreon is exploring the application of additional Sharma, P. et al. Nature Rev. Cancer 11, 805–812 (2011). RCC, renal cell carcinoma; TCR, T cell receptor; TIL, tumour-infiltrating lymphocyte; Topalian, S. L., Weiner, G. J. & Pardoll, D. M. Clin. Oncol. 29, 4828–4836 (2011). Copyedited by Mariam Faruqi. trial and is being developed under a collaboration agreement with the National Cancer ACI product candidates and small molecules for the potential treatment of a variety of 2012 Nature Publishing Group. TLR, Toll-like receptor; TNF, tumour necrosis factor; TReg cell, regulatory T cell; van Seters, M. et al. N. Engl. J. Med. 358, 1465–1473 (2008). © Institute. For more information, visit www.bavarian-nordic.com cancers. Visit us at www.dendreon.com VIN, vulvar intraepithelial neoplasia. Weber, J. et al. Clin. Cancer Res. 17, 1664–1673 (2011). http://www.nature.com/nrd/posters/cancerimmuno

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