Clinical Use of Dendrtitic Cell Vaccine

www.thelancet.com/oncology Vol 15 June 2014 e257

Review

Clinical use of dendritic cells for cancer therapySébastien Anguille, Evelien L Smits, Eva Lion, Viggo F van Tendeloo, Zwi N Berneman

Since the mid-1990s, dendritic cells have been used in clinical trials as cellular mediators for therapeutic vaccination of patients with cancer. Dendritic cell-based immunotherapy is safe and can induce antitumour immunity, even in patients with advanced disease. However, clinical responses have been disappointing, with classic objective tumour response rates rarely exceeding 15%. Paradoxically, fi ndings from emerging research indicate that dendritic cell-based vaccination might improve survival, advocating implementation of alternative endpoints to assess the true clinical potency of dendritic cell-based vaccination. We review the clinical eff ectiveness of dendritic cell-based vaccine therapy in melanoma, prostate cancer, malignant glioma, and renal cell carcinoma, and summarise the most important lessons from almost two decades of clinical studies of dendritic cell-based immunotherapy in these malignant disorders. We also address how the specialty is evolving, and which new therapeutic concepts are being translated into clinical trials to leverage the clinical eff ectiveness of dendritic cell-based cancer immunotherapy. Specifi cally, we discuss two main trends: the implementation of the next-generation dendritic cell vaccines that have improved immunogenicity, and the emerging paradigm of combination of dendritic cell vaccination with other cancer therapies.

Introduction2013 marked the 40th anniversary of the discovery by Cohn and Steinman1 of a new type of immune cell: dendritic cells. Although our knowledge of their biology and function is incomplete, evidence shows that dendritic cells play a crucial part in the induction of antitumour immunity.2 Immunotherapeutic approaches involving dendritic cells aim to capitalise on the ability of the cells to direct cytotoxic T lymphocytes and natural killer cells to become potent antitumour eff ectors capable of eradicating malignant cells (fi gure).3 The basic immuno logical principles that provide a compelling rationale for use of dendritic cells in immunotherapy and the diff erent ways to prepare these cells for clinical application have been reviewed elsewhere,2,4 and are beyond the scope of this Review. In this Review, we fi rst aim to examine the most important lessons gained from almost two decades of clinical studies of dendritic cell-based immunotherapy, particularly regarding the actual therapeutic usefulness of dendritic cells. We then describe how the specialty of dendritic cell-based immunotherapy is evolving, and provide an update of new models and approaches that are being adopted in clinical trials.

Since the fi rst published clinical trials in the mid-1990s, many early-phase clinical trials have been done across a wide range of tumour types. Dendritic cell-based treatments have been tested most often in patients with malignant melanoma,5 with more than 1250 patients treated (appendix pp 2–3), followed by prostate cancer (>750 patients treated; appendix p 4), malignant glioma (>500 patients treated; appendix p 5), and renal cell cancer (>250 patients treated; appendix p 6). These malignant diseases are the only tumour types in which phase 3 clinical trials of these treatments have been done or are underway (table 1). Therefore, in this Review we focus on these four tumour types, and use them to summarise the conclusions that can be gathered about the clinical use of dendritic cells in cancer immunotherapy.

SafetyThe safety of dendritic cell-based immunotherapy has been well documented in many phase 1 clinical studies.6 Local reactions at the injection sites (ie, pain, rash, and pruritus) are common, but these reactions are generally mild and self-limiting.6 Systemic side-eff ects, including pyrexia, malaise, and other infl uenza-like symptoms, can occur; however, systemic grade 3–4 (US National Cancer Institute-Common Terminology Criteria) toxicity is extremely uncommon when dendritic cell vaccination is given as monotherapy.6 One particular concern with immunotherapy is the possibility of induction of autoimmunity.7 However, cancer vaccine strategies are rarely associated with severe immune-related toxicity, which contrasts sharply with other immunotherapeutic methods such as monoclonal antibodies and cytokines.7 For example, immune-related adverse events have been reported in up to 60% (of which 15% are grade 3–4 toxicity) of patients treated with the anti-cytotoxic T lymphocyte antigen-4 (CTLA-4) monoclonal antibody ipilimumab,8 which has been approved by US and European health authorities for the treatment of melanoma.

In line with its low toxicity, dendritic cell-based immunotherapy is expected to preserve the quality of life of patients with cancer.9 Quality of life is an important outcome in assessment of novel anticancer agents, especially in the non-curative setting. However, reports on the quality-of-life outcomes of dendritic cell-based immunotherapy are scarce. One study9 assessing 55 patients with renal cell carcinoma treated with dendritic cells showed no negative eff ect of dendritic cell-based immunotherapy on quality of life, thereby comparing favourably with other existing and emerging therapies for renal cell carcinoma that can cause substantial toxicity and seriously impair quality of life.

Antitumour immune responsesThe main goal of cancer vaccine strategies involving dendritic cells is to stimulate tumour antigen-specifi c cytotoxic T lymphocytes that can recognise and eliminate

Lancet Oncol 2014; 15: e257–67

Center for Cell Therapy and Regenerative Medicine, Antwerp University Hospital, Edegem, Belgium (S Anguille MD, Prof E L Smits PhD, Prof Z N Berneman FRCP); and Laboratory of Experimental Hematology, Tumor Immunology Group (TIGR), Vaccine and Infectious Disease Institute (VAXINFECTIO) (S Anguille, E Lion, Prof V F van Tendeloo PhD, Prof Z N Berneman), and Center for Oncological Research (Prof E L Smits), University of Antwerp, Faculty of Medicine and Health Sciences, Antwerp, Belgium

Correspondence to:Dr Sébastien Anguille, Antwerp University Hospital (UZA), Center for Cell Therapy and Regenerative Medicine (U111), Wilrijkstraat 10, 2650 Edegem, [email protected]

See Online for appendix

http://crossmark.crossref.org/dialog/?doi=10.1016/S1470-2045(13)70585-0&domain=pdf

e258 www.thelancet.com/oncology Vol 15 June 2014

Review

cancer cells in an antigen-specifi c way.2 According to results of a meta-analysis of dendritic cell-based immunotherapy, such cellular immune responses can be elicited in 77% of patients with prostate cancer and 61% with renal cell carcinoma.6 In view of the fact that most of these patients have metastatic disease, this result confi rms that active immunisation with dendritic cells can elicit adaptive antitumour immunity in many patients, even in those with advanced disease who are thought to be less immune responsive.10

Emerging evidence from clinical trials indicates that dendritic cells, in addition to inducing tumour-specifi c cytotoxic T lymphocytes, can also enhance natural-killer-cell immunity.11 Positive natural-killer-cell responses (eg, increases in frequency, or induction of phenotypic or functional activation, or both) have been noted in about 50% of patients after dendritic cell vaccination.11 This

fi nding is particularly relevant in view of the growing evidence indicating that natural killer cells play a key part in the generation of protective anti-tumour immunity.11 Natural killer cells can contribute to tumour rejection both directly and indirectly by supporting the generation of cytotoxic T-lymphocyte immunity.11 In a murine melanoma model, Boudreau and colleagues12 showed that dendritic cells mediate tumour eradication via both cytotoxic T lymphocytes and natural killer cells. Notably, this eff ect was completely abrogated after natural-killer-cell depletion,12 which underscores the possibly pivotal role of natural killer cells in the development of eff ective antitumour immunity by dendritic cell vaccination.11,12

Taken together, these data indicate that dendritic cell-based immunotherapy can elicit adaptive and innate antitumour immunity in at least half of all patients. This action, coupled with the low occurrence of immune-related adverse events, challenges the notion that induction of cancer immunity by immunotherapy must come at the cost of autoimmunity, as has been suggested for other immunotherapies such as ipilimumab.7

Overall objective response Despite their favourable safety profi les and proven immunogenicity, cancer vaccine strategies have received a great deal of criticism, and even scepticism, because of their poor therapeutic effi cacy in terms of inducing objective clinical responses.13 The same criticism has also been levied at dendritic cell-based cancer vaccine approaches.14 We did a systematic review of all published clinical trials to document the proportion of patients who had an objective response (achieving either a complete response or partial response as defi ned by WHO criteria, or by the Response Evaluation Criteria In Solid Tumors [RECIST]13) after dendritic cell vaccination in melanoma, prostate cancer, malignant glioma, and renal cell carcinoma (appendix pp 1–12). From this review, we conclude that the clinical benefi t of dendritic cell-based immunotherapy in terms of objective response is real, but small. With 8·5% of melanoma patients achieving an objective response (appendix pp 2–3), dendritic cell therapy has similar effi cacy to dacarbazine (the standard chemotherapeutic drug for treatment of melanoma) or to ipilimumab, for which 5–15% of patients have an objective response.15,16 For prostate cancer, 7·1% of patients treated with dendritic cell therapy had an objective response when assessed by either imaging studies or by assessment of the prostate-specifi c antigen (PSA) tumour marker level (appendix p 4), which is similar to the 10% of patients with metastatic, androgen-resistant prostate cancer who are treated with conventional chemotherapeutic drugs.17 In patients with malignant glioma, 15·6% of patients treated with dendritic cell therapy had an objective response (appendix p 5). In advanced renal cell carcinoma, dendritic cell therapy produces an objective response in 11·5% of patients

Figure: Combination strategies to maximise the therapeutic eff ectiveness of dendritic cell-based immunotherapy and their underlying mechanisms of actionDendritic cell-based cancer therapies seek to exploit the intrinsic capacity of dendritic cells to stimulate antitumour immune eff ector cells, such as tumour antigen-specifi c cytotoxic T lymphocytes and natural killer cells. Therapeutic interventions that aim to enhance the strength of the immune eff ector response (A), reverse tumour-associated immunosuppression (B), or reduce the tumour burden and increase the immune susceptibility of the tumour cells (C), are being actively pursued in combination with dendritic cell therapy. DC=dendritic cell. MHC/Ag=antigen bound to major histocompatibility complex. TCR=T-cell receptor. CTL=cytotoxic T lymphocyte. NK=natural killer cell. TLR-L=toll-like receptor ligand. mAb=monoclonal antibody. CTLA-4=cytotoxic T lymphocyte antigen-4. PD-1=programmed death-1. MDSC=myeloid-derived suppressor cell. Treg=regulatory T cell. IMID=immunomodulatory drug (eg, lenalidomide). TKI=tyrosine kinase inhibitor (eg, sunitinib). COX-2 inhibitor=cyclooxygenase-2 inhibitor. ATRA=all-trans retinoic acid. VEGF=vascular endothelial growth factor. IDO=indoleamine-2,3-dioxygenase. 1-MT=1-D-methyl-tryptophan. TC=tumour cell. MRD=minimal residual disease.

DC

TC

TC

TC

Interleukin 2

NK

TCR

MDSC

αCD25mAb

αCTLA-4mAb

αPD-1mAb

Denileukindiftitox

Treg

IMID/TKI

IDO

1-MT

TLR-L/cytokinesVEGF

ATRACOX-2inhibitor

CTLMHC/Ag

Hormonetherapy

Radiationtherapy

Chemotherapy

AdoptiveT-cell therapy

Decrease oftumour mass;immunogeniccell death

Increase of lymphopenia-associatedcytokines

Decrease ofTregs, MDSCs

Patient selection• MRD or low tumour burden

(increase in likelihood ofdeveloping immunity)

• Early disease stage(increase in time for immunity to develop)

Decrease in tumour burdenIncrease in tumour immunogenicity

Reversal ofimmunosuppression

Increase in immune effector response

A B C


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(appendix p 6), which is also similar to that obtained with other immunotherapies such as interleukin 2.18

Survival benefi tWhereas objective response is a rapid and direct parameter with which to assess the antitumour activity of an experimental treatment, survival—particularly overall survival—is generally thought of as the most important outcome measure of therapeutic benefi t.19,20 Table 2 provides an overview of all published trials5,21–62 of dendritic cell vaccines in melanoma, prostate cancer, malignant glioma, and renal cell carcinoma in which overall survival comparisons have been done. Although results of two melanoma trials did not show survival benefi t,5,22 an increase in median overall survival of at least 20% has been documented in most studies (table 2).21,23–35 Although many of these trials were early phase and not designed primarily to measure survival, the results obtained are nevertheless noteworthy, especially in view of the fact that the bar for establishment of a clinically meaningful improvement in median overall survival is generally set at 20%.63 Perhaps the most compelling evidence that dendritic cell therapy can confer survival benefi t comes from the IMPACT study in prostate cancer (table 2).42 In this phase 3 randomised controlled trial, the dendritic cell-based therapeutic sipuleucel-T (Dendreon, Seattle, WA) showed signifi cantly larger median overall survival of patients with metastatic hormone-resistant prostate cancer than did placebo (table 1): median overall survival was 25·8 months in the experimental group versus 21·7 months in the control group.42 On the basis of this survival advantage and despite few patients achieving an objective response (<5%), sipuleucel-T was approved by the US Food and Drug Administration in 2010.3 Phase 3 trials using overall survival as the primary endpoint are underway in patients with advanced melanoma, glioma, and renal cell carcinoma (table 1).

Importantly, a positive association between immunity induced by dendritic cells and patient survival is

increasingly being reported (appendix pp 14–15). For example, an integrated analysis of the immune monitoring data collected during the IMPACT trial and two other phase 3 studies of sipuleucel-T in prostate cancer39,40,42 has shown a correlation between the induction of antigen-specifi c immune responses by sipuleucel-T and prolonged overall survival.64 These data provide a mechanism for the clinical benefi t noted in patients with prostate cancer treated with sipuleucel-T, and link the increased overall survival in these patients to the induction of tumour-specifi c immunity.6

Therapeutic eff ectivenessThe observed dissociation between objective response and survival indicates that alternative surrogate endpoints should be used to assess the therapeutic eff ectiveness of dendritic cell-based immunotherapy. As outlined, dendritic cell-based immunotherapeutic approaches can positively aff ect clinical outcome in terms of increasing patient survival rather than by inducing objective tumour responses. Although this notion might seem counterintuitive, for several tumour types and disease settings tumour response criteria cannot be used to accurately assess the eff ect of a certain treatment on survival.65 This absence of association between objective response and overall survival has been reported particularly with the use of immunotherapeutic drugs and targeted therapies.66 For example, ipilimumab therapy signifi cantly improved overall survival of patients with metastatic melanoma by 4·5 months (compared with a control group given a tumour peptide vaccine),8 despite only 5–15% of patients having an objective response.16 A phase 3 clinical trial of the tyrosine kinase inhibitor sorafenib in patients with advanced renal cell carcinoma yielded similar results, in which only 10% of patients had an objective response,67 but survival was nevertheless signifi cantly prolonged by 3·5 months (compared with a placebo control group).68 These two examples, along with the evidence presented in this Review, suggest that the dissociation between objective

Dendritic cell product Control group Status ClinicalTrials.gov identifi er

Melanoma Autologous monocyte-derived DCs pulsed with melanoma peptidesAutologous DCs mixed with irradiated autologous tumour cells suspended in GM-CSF (melapuldencel-T)

DacarbazineAutologous PBMCs suspended in GM-CSF

CompletedNot yet recruiting

NA5

NCT01875653

Prostate Autologous APCs (including DCs) loaded with PAP/GM-CSF (sipuleucel-T)

Autologous APCs Completed NCT00005947NCT00065442NCT00779402NCT01133704

Brain (GBM) Autologous DCs pulsed with autologous tumour lysate (DC-VAX-L) Autologous PBMCs Recruiting NCT00045968

Renal Autologous DCs electroporated with autologous tumour mRNA and CD40L mRNA, in combination with sunitinib (AGS-003)

Sunitinib Recruiting NCT01582672

Excludes one study in prostate cancer that was withdrawn before enrolment (NCT00043212) and three studies with phase 2/3 design (NCT01759810, NCT01782274, and NCT01782287). DCs=dendritic cells. GM-CSF=granulocyte macrophage colony-stimulating factor. PBMCs=peripheral blood mononuclear cells. APCs=antigen-presenting cells. PAP/GM-CSF=chimeric antigen consisting of the prostate tumour antigen prostatic acid phosphatase (PAP) linked to GM-CSF. GBM=glioblastoma multiforme. NA=not available.

Table 1: Overview of completed and ongoing randomised phase 3 clinical trials of dendritic cell-based cancer immunotherapy, by cancer type


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Evidence level Overall survival Dendritic cell product

DC group (months)

Control group (months)

% change Dendritic cell type Activation

Melanoma

N=1121 III-3 9·3 4·0 +133% IL-4 moDCs MCM

N=1322 III-1 6·2 14·8 −58% IL-4 moDCs Immature

N=5423–25 III-1 64·0 31·0 +107% IL-4 moDCs GM-CSF

N=1726 III-3 22·4 8·0 +180% IL-4 moDCs TNF-α

N=1127 III-3 7·3 4·0 +83% IL-4 moDCs TNF-α/IL-1β/IL-6/PGE2

N=16/22*28 III-2 12·3 5·8 +112% IL-4 moDCs TNF-α/IL-1β/IL-6/PGE2

N=2029,30 III-3 8·6 4·0 +115% IL-4 moDCs TNF-α+Poly(I:C)

N=535 II 9·3 11·6 −20% IL-4 moDCs TNF-α/IL-1β/IL-6/PGE2



N=2433 III-3 13·6 7·3 +86% IL-4 moDCs Immature

N=2934 III-3 15·0 8·3 +81% IL-4 moDCs TNF-α/PGE2

N=1535 III-3 22·0 7·6 +189% Natural pDCs FSME-IMMUN

Prostate

N=3336–38 III-3 >20·0 6·0 +233% IL-4 moDCs Immature

N=147/22539,40 II 23·2 18·9 +23% Sipuleucel-T GM-CSF

N=1241 III-3 21·0 12–19 +10–75% IL-4 moDCs TNF-α/PGE2

N=341/51242 II 25·8 21·7 +19% Sipuleucel-T GM-CSF

Brain

N=8/1443 III-2 33·3 7·5 +344% IL-4 moDCs Immature



N=1846 III-3 15·7 13·1 +20% IL-4 moDCs OK-432

N=5647 III-3 9·6 6·0–7·0 +39–62% IL-4 moDCs TNF-α/IL-1β/PGE2

N=1248 III-3 22·8 15·6 +46%; NS IL-4 moDCs TNF-α/IL-1β/IL-6

N=849 III-3 24·0 12·0 +100% IL-4 moDCs TNF-α/IL-1β/PGE2

N=16/1750 III-3 17·0 12·5 +36% IL-4 moDCs Immature

N=1051 III-3 28·0 14·6 +92% IL-4 moDCs TNF-α/PGE2

N=15†52 III-3 35·9 14·0 +156% IL-4 moDCs +Imiquimod or poly(I:C)LC

N=7753 III-3 18·3 14·6 +25% IL-4 moDCs TNF-α/IL-1β/PGE2


N=1355 III-2 17·0 10·5 +62% IL-4 moDCs: TNF-α/IL-1β/PGE2

N=556 III-3 27·0 12·3 +120% IL-4 moDCs TNF-α/IFN-α/Poly(I:C)

N=757 III-3 24·9 19·2 +30%; NS IL-4 moDCs TNF-α/IL-1β/IL-6/PGE2

Renal

N=1058 III-3 19·8 9·0–12·0 +65–120% IL-4 moDCs Immature

N=959 III-3 29·0 12·0 +142% IL-4 moDCs MCM/CD40L/IFN γ


N=1861 III-3 >18·0 13·8 +29% IL-4 moDCs TNF-α +/− PGE2

N=10 (PR)62 III-3 9·1‡ 5·3 +72% moDCs CD40L mRNA

N=11 (IR)62 III-3 39·5‡ 20·7 +91% moDCs CD40L mRNA

Last update: Nov 14, 2013. DC=dendritic cell. N=total number of vaccinated patients. PR=poor-risk group. IR=intermediate-risk group. Evidence level is according to NHMRC gradation system (http://www.nhmrc.gov.au), derived from diff erent trial types: II=randomised controlled trial. III-1=pseudorandomised controlled trial (eg, other treatment). III-2= trial including a non-randomised concurrent control group. III-3=trial without concurrent control group (eg, historical controls or comparison of two or more single-group trials). % change=percentage change from overall survival in control group to DC group. NS=not signifi cant. IL-4 moDCs=interleukin-4-diff erentiated monocyte-derived DCs. pDCs=plasmacytoid DCs. MCM=monocyte-conditioned medium. GM-CSF=granulocyte macrophage colony-stimulating factor. TNF=tumour necrosis factor. PGE2=prostaglandin E2. Poly(I:C)=polyinosinic:polycytidylic acid, a toll-like receptor (TLR)3 agonist. Poly(I:C)LC=poly(I:C) stabilised with lysine and carboxymethylcellulose. FSME-IMMUN=tick-borne encephalitis vaccine. OK-432=picibanil, a TLR4 agonist. IFN=interferon. *M1c patient subgroup. †newly diagnosed glioblastoma multiforme patient subgroup. ‡combined with sunitinib.

Table 2: Overview of dendritic cell vaccine trials in melanoma, prostate cancer, primary brain tumours (glioma), and renal cell cancer reporting overall survival outcome


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response and overall survival is a class-specifi c occurrence of immunotherapies and targeted therapies,66 and corroborate the notion that the objective response might not show the true clinical activity of these therapies.66,69,70 If eff ective, classic cytotoxic drugs usually cause fairly rapid reductions in tumour size and, in such cases, the objective response is a suitable parameter to assess treatment response.69,70 By contrast, immunotherapies often produce diff erent clinical response patterns, none of which are accurately captured by establishment of objective response.69,70 Among these atypical response profi les, which are also frequently observed in the context of dendritic cell-based immunotherapy, are delayed initial increases in tumour burden associated with infl ammation or immune cell infi ltration of the tumour lesions later followed by regression, and changes in disease progression kinetics.21,71 The response profi le changes in disease progression kinetics have been well documented in patients with prostate cancer, in whom results of many studies show that therapeutic cancer vaccines, including dendritic cell-based vaccines, can attenuate the PSA progression rate without signifi cantly reducing PSA levels.71,72 Such response patterns cannot be classifi ed as objective with classic response assessment criteria; however, they might be highly clinically relevant in view of the association between changes in PSA kinetics and the survival of patients with prostate cancer.73 Taken together, these data underscore the idea that dendritic cell-based immunotherapeutic strategies, and, by extension, all cancer immunotherapies, necessitate effi cacy endpoints other than the traditional outcome parameters used in oncology clinical trials.19,70 As outlined, overall survival is the most appropriate endpoint in late-stage clinical trials.20 For early-phase clinical trials, the immune-related response criteria might be a valid alternative to the classic WHO or RECIST criteria to assess antitumour responses, because they accommodate the atypical tumour response patterns recorded with immunotherapies.69,70

How is the specialty evolving?TrendsAmong the studies of dendritic cell cancer vaccines registered at http://www.clinicaltrials.gov, two main emerging trends in dendritic cell-based anticancer immunotherapy can be identifi ed. The fi rst revolves around the use of next-generation dendritic cell products with improved immunostimulatory activity. The second is to potentiate the eff ectiveness of dendritic cell immunotherapy through combination therapy.

Next-generation dendritic cell vaccinesMost published clinical trials have been done with early-generation dendritic cell vaccines, including dendritic cell-enriched cell preparations (eg, sipuleucel-T—a crude preparation of prostate antigen-loaded, GM-CSF-activated blood mononuclear cells of which dendritic

cells constitute only a small proportion) and interleukin-4 monocyte dendritic cells (dendritic cells generated ex vivo from peripheral blood monocytes in the presence of GM-CSF and interleukin 4; table 2).3 The interleukin-4 monocyte dendritic cell—either used in its immature form or after activation or maturation with a pro-infl ammatory cytokine cocktail composed of tumour necrosis factor (TNF) α, interleukin 1β, interleukin 6, and prostaglandin E2—is by far the most commonly used dendritic cell type in clinical trials (table 2).4

Which dendritic cell vaccine parameters are important for clinical eff ectiveness is not fully understood. Although clinical benefi t has been shown in trials using immature interleukin-4 monocyte dendritic cells (table 2) and many individual studies have not established a correlation between dendritic cell activation parameters and survival outcome,28,31,33,43 results of a meta-analysis of dendritic cell immunotherapy in prostate cancer have shown a clear superiority of mature monocyte dendritic cells over their immature counterparts in terms of clinical outcome.6 Similar observations have been made in the context of melanoma74 and malignant glioma.46 In addition to maturation state, the ability of dendritic cells to produce interleukin 12p70—which favours the induction of a protective T-helper type 1 (Th1) immune response—is being increasingly recognised as an important determinant of clinical activity.3 In two clinical trials, one in glioma75 and one in melanoma,76 high concentrations of dendritic cell-derived interleukin 12p70 were predictive of favourable clinical outcome.

This evidence explains the impetus behind the recent and ongoing eff orts to develop the next generation of dendritic cell vaccines biased to induce a Th1 immune response (referred to as type 1-polarised dendritic cells) and endowed with a superior capacity to elicit tumour antigen-specifi c cytotoxic T lymphocytes and natural-killer-cell immunity.3 The aim of this work is not to provide an exhaustive compilation of all available next-generation dendritic cell vaccine protocols, but to touch on some salient examples to show the main trends in this fi eld of research. Several groups, including ours, have shown interest in use of Langerhans cell-type dendritic cells as vehicles for dendritic cell vaccination in view of their remarkable effi ciency to stimulate cytotoxic T lymphocyte immunity.77 Langerhans cell-like dendritic cells can be derived from CD34-positive haemopoietic progenitors,78 or from CD14-positive monocytes cultured with interleukin 15 (instead of interleukin 4).79 Clinical studies using these Langerhans cell-type dendritic cells are underway in melanoma (NCT00700167,78 NCT01456104, and NCT01189383). In view of the key role of interleukin 12p70 and the observed absence of interleukin 12p70 production with use of the classic maturation cocktail of TNF-α, interleukin 1β, interleukin 6, and prostaglandin E2, much work has been devoted to development of alternative maturation-inducing regimens.4 Examples of maturation stimuli that


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allow for the generation of dendritic cells with the desired capacity to produce interleukin 12p70 are CD40L with interferon γ;76 toll-like receptor ligands (eg, TLR3 agonist poly[I:C]);80 or a combination of TNF-α, interleukin 1β, interferon γ, interferon α, and polyI:C.75 In patients with malignant glioma, dendritic cells matured with the latter combination (designated as α-type-1-polarised dendritic cells) have shown potent ability to produce interleukin 12p70 and to augment the expression of the cytotoxic T-lymphocyte-attracting chemokine CXCL10 in the tumour microenvironment,75 which has been identifi ed as another key factor in the therapeutic activity of dendritic cell vaccines in a murine study of malignant glioma.81 The clinical eff ectiveness of α-type-1-polarised dendritic cells is being further assessed in several clinical trials in melanoma (NCT00390338), prostate cancer (NCT00970203), and glioma (NCT00766753).

Combination therapyCategorisationThe appendix (pp 16–18) provides an overview of the diff erent therapeutic interventions being assessed in terms of their potential synergistic interaction with dendritic cell vaccination. In this Review, for clarity, we have divided these interventions into three categories on the basis of their principal mechanism of action (fi gure).

Interventions that enhance the strength of the immune eff ector responseImmune inhibitory pathways often dominate in patients with cancer and can aff ect the eff ectiveness of dendritic cell-based immunotherapy by preventing cytotoxic T lymphocytes and natural killer cells from exerting their eff ector function (fi gure). The immune checkpoint receptors CTLA-4 and programmed death-1 (PD-1) are among the best understood molecules involved in the negative regulation of cytotoxic T-lymphocyte function.3 In recent years, several monoclonal antibodies that can interfere with these inhibitory molecules have become available for clinical application, opening up the prospect of their use in combination with dendritic cell-based immunotherapy.3 Preliminary clinical evidence obtained in patients with advanced melanoma suggests that dendritic cell therapy in combination with CTLA-4-targeting monoclonal antibodies is more eff ective than is use of these agents as monotherapies.82,83 However, we believe that these monoclonal antibodies should be used with caution in view of their potential (immune-related) toxicity. Anti-PD-1 monoclonal antibodies seem to have a more favourable toxicity profi le, and can even be combined with ipilimumab without a signifi cant increase in the rate of immune-related adverse events.84,85 In view of this profi le, therapeutic blockade of the PD-1/PD ligand 1 pathway might be a more viable strategy from the perspective of clinical applicability. Several anti-PD-1 monoclonal antibodies have entered the clinical

trial stage,84,85 one of which (pidilizumab; CT-011) is being tested in combination with dendritic cell therapy in four clinical trials (appendix p 18).

Toll-like receptor agonists and cytokines (eg, interferon α) have also come under intense scrutiny as dendritic cell vaccine adjuvants to harness the antitumour eff ector response (fi gure).86,87 These stimuli can either be incorporated into the vaccine itself—eg, as ex-vivo maturation agents—or applied concomitantly with the dendritic cell vaccine (appendix pp 17–18).75 Perhaps the most extensively studied cytokine used in combination with dendritic cell vaccination is interleukin 2. Despite strong preclinical evidence supporting this combination,88 results of clinical trials have not shown that the addition of interleukin 2 to dendritic cell vaccine regimens results in a superior induction of antitumour immunity.89,90 Moreover, interleukin 2 could negatively aff ect dendritic cell immunotherapy by causing an undesired stimulation of regulatory T cells (Tregs) or of myeloid-derived suppressor cells (MDSCs), or both (fi gure).32,91

The antitumour immune responses elicited by dendritic cell therapy can also be potentiated by stimulation of the endogenous production of immuno-stimulatory cytokines. This process can be achieved with lymphodepleting chemotherapy regimens, such as temozolomide or cyclophosphamide with or without fl udarabine.92 These therapies seek to reboot the immune system by elimination of negative immune-cell populations (eg, Tregs) and creation of an optimum cytokine milieu (eg, interleukin 7 and interleukin 15) for expansion of antitumour eff ector cells, including natural killer cells and tumour antigen-specifi c cytotoxic T lymphocytes (fi gure).93,94 This recovery phase after lymphodepletion provides an ideal opportunity for dendritic cell vaccination in combination with adoptive transfer of immune eff ector cells (fi gure).94 This strategy has generated promising results in preclinical studies and in a pilot clinical trial,95,96 and is being pursued in several ongoing clinical studies (appendix p 18).

Interventions that reverse tumour-associated immunosuppressionThe translation of dendritic cell-induced antitumour immunity into clinical activity needs to overcome the immune suppressive barrier that is imposed by Tregs, MDSCs, and other negative immune regulators (fi gure).3,10,97 Tregs are by far the best characterised cells that prevent the generation of eff ective antitumour responses.98 Two main strategies are being used to modulate Tregs in dendritic cell-based immunotherapy protocols. First, dendritic cells themselves can be harnessed to target Tregs, which can be achieved, for example, by loading dendritic cells with antigenic components of the Treg transcription factor forkhead box P3 (FoxP3) to mount a FoxP3-directed cytotoxic T-lymphocyte response.98 Second, dendritic cells can be combined with Treg-targeting drugs, such as the


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monoclonal antibodies basiliximab and daclizumab (appendix p 17; fi gure).98 These monoclonal antibodies are directed towards the interleukin-2 receptor α chain (CD25), which is abundantly expressed on the surface of Tregs (fi gure). The combination of dendritic cell therapy and daclizumab has been examined in patients with metastatic melanoma.99 Daclizumab eff ectively depleted Tregs but also targeted tumour-specifi c T cells (presumably because of the expression of CD25 on activated T cells) and impaired their functionality.99 Denileukin diftitox, a fusion protein composed of interleukin 2 and diphtheria toxin, is another CD25-directed approach to deplete Tregs (fi gure). In patients with advanced renal cell carcinoma, the addition of denileukin diftitox to dendritic cell vaccination resulted in a 16-fold increase in the frequency of tumour-specifi c cytotoxic T lymphocytes.100 In another study,101 dendritic cell therapy induced a more persistent cytotoxic T-lymphocyte response after Tregs were depleted by denileukin diftitox. By contrast, Baur and colleagues102 showed that denileukin diftitox can negatively aff ect the capacity of dendritic cells to induce tumour-specifi c cytotoxic T lymphocytes by inducing a tolerogenic phenotype in dendritic cells, and by promoting the survival of non-activated Tregs.102 Moreover, CD25 can also be expressed on activated natural killer cells (fi gure) and, consequently, denileukin diftitox can also lead to depletion of natural killer cells.103 Collectively, these data indicate that CD25-based Treg-targeting strategies, such as denileukin diftitox, can produce paradoxical immunological eff ects that can impair the activity of dendritic cell vaccination. Non-CD25-based methods, such as low-dose cyclophosphamide or 1-methyl-D-tryptophan,98 might therefore be more appropriate. Clinical trials of metronomically dosed cyclophosphamide in combination with dendritic cell therapy have yielded mixed results and have not consistently shown a reduction in the frequency of Tregs.93 However, these results do not necessarily preclude a possible benefi cial eff ect of cyclophosphamide on dendritic cell vaccine effi cacy, because cyclophosphamide might enhance antitumour immunity via mechanisms other than Treg elimination (eg, by directly aff ecting the dendritic cell compartment).104

Indoleamine-2,3-dioxygenase, an immunoregulatory enzyme that supports Treg function and numbers, can be inhibited by 1-methyl-D-tryptophan (fi gure);87 clinical trials of its combined use with dendritic cell therapy are underway (appendix p 17). The antitumour activities of several newer anticancer drugs, such as the VEGF-targeting monoclonal antibody bevacizumab, the immuno modulatory drug lenalidomide, and the tyrosine kinase inhibitors dasatinib and sunitinib also seem to rely, at least in part, on their inhibitory activities on Tregs (fi gure).105,106 Sunitinib is being tested in combination with dendritic cell-based immunotherapy in a phase 3 clinical trial in patients with advanced renal cell carcinoma (table 1, appendix pp 17–18).

In addition to Tregs, MDSCs are being increasingly recognised as important mediators of tumour-induced immunosuppression.107 MDSCs exert negative eff ects on both T cells and natural killer cells,107 and can directly impair the activity of dendritic cell vaccines.108 This eff ect provides a compelling rationale to combine dendritic cell vaccination with MDSC-targeted interventions, such as VEGF inhibitors, lenalidomide, all-trans retinoic acid, chemotherapeutic drugs (eg, gemcitabine), and cyclooxygenase-2 (COX-2) inhibitors (fi gure, appendix pp 17–18).105,107 COX-2 inhibitors diminish expression of the MDSC-attracting chemokine CCL2 in the tumour bed, and promote tumour infi ltration by cytotoxic T lymphocytes through increasing the concentration of CXCL10, thereby creating a favourable immune context for the induction of antitumour immunity by dendritic cells.75,109 Tyrosine kinase inhibitors such as sunitinib and vemurafenib can also reverse MDSC-mediated immuno suppression.107,110 Vemurafenib, a BRAF inhibitor, has become available for treatment of advanced BRAFV600E-positive melanoma.111 Apart from its direct antimelanoma activity, vemurafenib exerts a wide range of benefi cial immunomodulatory eff ects. Like COX-2 inhibitors, vemurafenib reduces tumour CCL2 expression and mobilises antitumour eff ector cells into the tumour microenvironment.111 These eff ects, coupled with its inhibitory action on Tregs111 and MDSCs,110 make vemurafenib an attractive candidate for combination therapy with dendritic cell vaccination.112

Interventions to reduce tumour burden and increase immune susceptibility of tumour cellsThe level of tumour-induced immunosuppression is a function of the total burden of the tumour.10 This observation led to the suggestion that immunotherapies might function less well in the context of high tumour burden.10 Ample evidence supports the hypothesis that patients with advanced or bulky disease are less likely to benefi t from cancer immunotherapy, including dendritic cell therapy, than are patients with less-advanced disease.97,113 A good example of this inverse association between tumour burden and the eff ectiveness of immunotherapy comes from haematology, in which dendritic cell therapy has shown little eff ectiveness in patients with relapsed or progressive acute myeloid leukaemia, but strong antileukaemic activity in patients with minimal residual disease.114,115

These considerations provide a rationale for combination of dendritic cell therapy with cytoreductive cancer treatments (eg, chemotherapy) to bring the patient to a state of low tumour burden or minimal residual disease state (fi gure).10,113 In view of the fact that chemotherapy by itself has immunosuppressive eff ects, and that patients heavily pretreated with chemotherapy are less responsive to subsequent immunotherapy,94 the idea of combination of immunotherapy and chemotherapy seems counter-intuitive. Nevertheless, this theory has been challenged by several clinical trials, the results of which showed that this


Review

combinatorial approach might be highly synergistic.92,97,116,117 Many mechanisms seem to be involved in the synergistic interaction between chemotherapy and dendritic cell therapy. Apart from the aforementioned immune-potentiating eff ects (ie, reversal of tumour-induced immunosuppression associated with high tumour burden, creation of a lymphopenic state favouring expansion of antitumour eff ector cells, and inhibition or depletion, or both, of Tregs and MDSCs), many chemotherapeutic drugs seem able to induce immunogenic tumour cell death, making these cells more susceptible to antitumour immunity elicited by dendritic cell therapy (fi gure).94,118 Dendritic cell therapies are being increasingly integrated into existing chemotherapy schedules, which indicates that the concept of chemoimmunotherapy is becoming an important treat ment model in the area of dendritic cell-based immunotherapy (appendix p 17). Other conventional anticancer treatments—ie, radiation therapy and hormonal therapy—also have pleiotropic immunomodulatory eff ects that extend beyond their primary mode of action, and that can be exploited to increase the activity of dendritic cell-based immunotherapy.97,119,120

ConclusionWe conclude that dendritic cell therapy is a safe and well tolerated immunotherapeutic method that can elicit immunity even in patients with advanced-stage cancer. This work also confi rms that dendritic cell-based interventions have only some capacity to produce objective tumour responses, as established by classic response assessment criteria such as RECIST. Although not all studies were designed primarily to measure survival, an increasing number indicate that dendritic cell therapy could confer a survival benefi t. These preliminary but encouraging survival data provide a strong incentive to begin a new series of clinical trials using overall survival as the primary endpoint or using surrogate endpoints for clinical eff ectiveness (eg, the proposed immune-related response criteria).69,70 We foresee that the specialty will benefi t from two developments, which are already beginning to be incorporated in clinical trials: the implementation of the next generation of dendritic cell

vaccines with optimised activity; and the rational use of these vaccines in combination with other anticancer therapies that could improve their eff ectiveness. These developments might hold the key to the full therapeutic potential of dendritic cells for cancer immunotherapy.

ContributorsSA researched the data, wrote the Review, and designed the fi gure. ELS,

EL, VFvT, and ZNB reviewed and revised the manuscript for intellectual

content.

Declaration of interestsWe declare no competing interests.

AcknowledgmentsWe thank Jan-Baptist Vermorken for critical reading of the manuscript,

and acknowledge the Research Foundation Flanders (FWO Vlaanderen),

the Flemish League against Cancer (Vlaamse Liga tegen Kanker), the

Belgian Foundation against Cancer (Stichting tegen Kanker), and the

Belgian public utility foundation VOCATIO for their invaluable support.

SA holds an Emmanuel van der Schueren fellowship of the Flemish

League against Cancer.

References1 Steinman RM, Cohn ZA. Identifi cation of a novel cell type in

peripheral lymphoid organs of mice. I. Morphology, quantitation, tissue distribution. J Exp Med 1973; 137: 1142–62.

2 Palucka K, Banchereau J. Cancer immunotherapy via dendritic cells. Nat Rev Cancer 2012; 12: 265–77.

3 Kirkwood JM, Butterfi eld LH, Tarhini AA, Zarour H, Kalinski P, Ferrone S. Immunotherapy of cancer in 2012. CA Cancer J Clin 2012; 62: 309–35.

4 Tacken PJ, de Vries IJ, Torensma R, Figdor CG. Dendritic-cell immunotherapy: from ex vivo loading to in vivo targeting. Nat Rev Immunol 2007; 7: 790–802.

5 Schadendorf D, Ugurel S, Schuler-Thurner B, et al, and the DC study group of the DeCOG. Dacarbazine (DTIC) versus vaccination with autologous peptide-pulsed dendritic cells (DC) in fi rst-line treatment of patients with metastatic melanoma: a randomized phase III trial of the DC study group of the DeCOG. Ann Oncol 2006; 17: 563–70.

6 Draube A, Klein-González N, Mattheus S, et al. Dendritic cell based tumor vaccination in prostate and renal cell cancer: a systematic review and meta-analysis. PLoS One 2011; 6: e18801.

7 Amos SM, Duong CP, Westwood JA, et al. Autoimmunity associated with immunotherapy of cancer. Blood 2011; 118: 499–509.

8 Hodi FS, O’Day SJ, McDermott DF, et al. Improved survival with ipilimumab in patients with metastatic melanoma. N Engl J Med 2010; 363: 711–23.

9 Leonhartsberger N, Ramoner R, Falkensammer C, et al. Quality of life during dendritic cell vaccination against metastatic renal cell carcinoma. Cancer Immunol Immunother 2012; 61: 1407–13.

10 Widén K, Mozaff ari F, Choudhury A, Mellstedt H. Overcoming immunosuppressive mechanisms. Ann Oncol 2008; 19 (suppl 7): vii 241–47.

11 Lion E, Smits EL, Berneman ZN, Van Tendeloo VF. NK cells: key to success of DC-based cancer vaccines? Oncologist 2012; 17: 1256–70.

12 Boudreau JE, Bridle BW, Stephenson KB, et al. Recombinant vesicular stomatitis virus transduction of dendritic cells enhances their ability to prime innate and adaptive antitumor immunity. Mol Ther 2009; 17: 1465–72.

13 Rosenberg SA, Yang JC, Restifo NP. Cancer immunotherapy: moving beyond current vaccines. Nat Med 2004; 10: 909–15.

14 Huber ML, Haynes L, Parker C, Iversen P. Interdisciplinary critique of sipuleucel-T as immunotherapy in castration-resistant prostate cancer. J Natl Cancer Inst 2012; 104: 273–79.

15 Robert C, Thomas L, Bondarenko I, et al. Ipilimumab plus dacarbazine for previously untreated metastatic melanoma. N Engl J Med 2011; 364: 2517–26.

16 Weber J. Overcoming immunologic tolerance to melanoma: targeting CTLA-4 with ipilimumab (MDX-010). Oncologist 2008; 13 (suppl 4): 16–25.

Search strategy and selection criteria

We selected references through a PubMed search with the terms “dendritic cells”, “cancer”, and “immunotherapy”. We retrieved data presented in table 1 and appendix pp 17–18 from the online clinical trial database http://www.clinicaltrials.gov with the search term “dendritic cells”. We excluded studies with the status withdrawn. We identifi ed relevant records for the data presented in table 2, appendix pp 2–12, and appendix pp 14–15 by a systematic search of PubMed for all studies published between Jan 1, 1995, and Nov 14, 2013, containing the following search terms: “dendritic cells” AND “clinical trial” AND “melanoma” OR “prostate cancer” OR “glioblastoma” OR “renal cell carcinoma”. We identifi ed additional records by screening bibliographies of key articles on the subject and by screening conference proceedings of the American Society of Clinical Oncology (ASCO). We excluded articles not published in English, case reports, and duplicate publications.


Review

17 Tay M-H, Nakabayashi M, Oh WK. Management of hormone refractory prostate cancer. In: Vogelzang NJ, Scardino PT, Shipley WU, Debruyne FMJ, Linehan WM, eds. Comprehensive textbook of genitourinary oncology, 3 edn. Philadelphia, PA: Lippincott Williams & Wilkins, 2006: 341–54.

18 Coppin C, Porzsolt F, Awa A, Kumpf J, Coldman A, Wilt T. Immunotherapy for advanced renal cell cancer. Cochrane Database Syst Rev 2005; 1: CD001425.

19 Madan RA, Gulley JL, Fojo T, Dahut WL. Therapeutic cancer vaccines in prostate cancer: the paradox of improved survival without changes in time to progression. Oncologist 2010; 15: 969–75.

20 Saad ED, Buyse M. Overall survival: patient outcome, therapeutic objective, clinical trial end point, or public health measure? J Clin Oncol 2012; 30: 1750–54.

21 Thurner B, Haendle I, Röder C, et al. Vaccination with mage-3A1 peptide-pulsed mature, monocyte-derived dendritic cells expands specifi c cytotoxic T cells and induces regression of some metastases in advanced stage IV melanoma. J Exp Med 1999; 190: 1669–78.

22 Slingluff CL Jr, Petroni GR, Yamshchikov GV, et al. Clinical and immunologic results of a randomized phase II trial of vaccination using four melanoma peptides either administered in granulocyte-macrophage colony-stimulating factor in adjuvant or pulsed on dendritic cells. J Clin Oncol 2003; 21: 4016–26.

23 Dillman R, Selvan S, Schiltz P, et al. Phase I/II trial of melanoma patient-specifi c vaccine of proliferating autologous tumor cells, dendritic cells, and GM-CSF: planned interim analysis. Cancer Biother Radiopharm 2004; 19: 658–65.

24 Dillman RO, Selvan SR, Schiltz PM, et al. Phase II trial of dendritic cells loaded with antigens from self-renewing, proliferating autologous tumor cells as patient-specifi c antitumor vaccines in patients with metastatic melanoma: fi nal report. Cancer Biother Radiopharm 2009; 24: 311–19.

25 Dillman RO, Cornforth AN, Depriest C, et al. Tumor stem cell antigens as consolidative active specifi c immunotherapy: a randomized phase II trial of dendritic cells versus tumor cells in patients with metastatic melanoma. J Immunother 2012; 35: 641–49.

26 Trefzer U, Herberth G, Wohlan K, et al. Vaccination with hybrids of tumor and dendritic cells induces tumor-specifi c T-cell and clinical responses in melanoma stage III and IV patients. Int J Cancer 2004; 110: 730–40.

27 Vilella R, Benítez D, Milà J, et al. Pilot study of treatment of biochemotherapy-refractory stage IV melanoma patients with autologous dendritic cells pulsed with a heterologous melanoma cell line lysate. Cancer Immunol Immunother 2004; 53: 651–58.

28 Kyte JA, Mu L, Aamdal S, et al. Phase I/II trial of melanoma therapy with dendritic cells transfected with autologous tumor-mRNA. Cancer Gene Ther 2006; 13: 905–18.

29 Nakai N, Asai J, Ueda E, Takenaka H, Katoh N, Kishimoto S. Vaccination of Japanese patients with advanced melanoma with peptide, tumor lysate or both peptide and tumor lysate-pulsed mature, monocyte-derived dendritic cells. J Dermatol 2006; 33: 462–72.

30 Nakai N, Katoh N, Kitagawa T, Ueda E, Takenaka H, Kishimoto S. Evaluation of survival in Japanese stage IV melanoma patients treated with melanoma antigen-pulsed mature monocyte-derived dendritic cells. J Dermatol 2008; 35: 801–03.

31 Hersey P, Halliday GM, Farrelly ML, DeSilva C, Lett M, Menzies SW. Phase I/II study of treatment with matured dendritic cells with or without low dose IL-2 in patients with disseminated melanoma. Cancer Immunol Immunother 2008; 57: 1039–51.

32 Ellebaek E, Engell-Noerregaard L, Iversen TZ, et al. Metastatic melanoma patients treated with dendritic cell vaccination, Interleukin-2 and metronomic cyclophosphamide: results from a phase II trial. Cancer Immunol Immunother 2012; 61: 1791–804.

33 Oshita C, Takikawa M, Kume A, et al. Dendritic cell-based vaccination in metastatic melanoma patients: phase II clinical trial. Oncol Rep 2012; 28: 1131–38.

34 Aarntzen EH, De Vries IJ, Lesterhuis WJ, et al. Targeting CD4(+) T-helper cells improves the induction of antitumor responses in dendritic cell-based vaccination. Cancer Res 2013; 73: 19–29.

35 Tel J, Aarntzen EH, Baba T, et al. Natural human plasmacytoid dendritic cells induce antigen-specifi c T-cell responses in melanoma patients. Cancer Res 2013; 73: 1063–75.

36 Murphy G, Tjoa B, Ragde H, Kenny G, Boynton A. Phase I clinical trial: T-cell therapy for prostate cancer using autologous dendritic cells pulsed with HLA-A0201-specifi c peptides from prostate-specifi c membrane antigen. Prostate 1996; 29: 371–80.

37 Tjoa BA, Erickson SJ, Bowes VA, et al. Follow-up evaluation of prostate cancer patients infused with autologous dendritic cells pulsed with PSMA peptides. Prostate 1997; 32: 272–78.

38 Tjoa BA, Simmons SJ, Bowes VA, et al. Evaluation of phase I/II clinical trials in prostate cancer with dendritic cells and PSMA peptides. Prostate 1998; 36: 39–44.

39 Small EJ, Schellhammer PF, Higano CS, et al. Placebo-controlled phase III trial of immunologic therapy with sipuleucel-T (APC8015) in patients with metastatic, asymptomatic hormone refractory prostate cancer. J Clin Oncol 2006; 24: 3089–94.

40 Higano CS, Schellhammer PF, Small EJ, et al. Integrated data from 2 randomized, double-blind, placebo-controlled, phase 3 trials of active cellular immunotherapy with sipuleucel-T in advanced prostate cancer. Cancer 2009; 115: 3670–79.

41 Hildenbrand B, Sauer B, Kalis O, et al. Immunotherapy of patients with hormone-refractory prostate carcinoma pre-treated with interferon-gamma and vaccinated with autologous PSA-peptide loaded dendritic cells—a pilot study. Prostate 2007; 67: 500–08.

42 Kantoff PW, Higano CS, Shore ND, et al, and the IMPACT Study Investigators. Sipuleucel-T immunotherapy for castration-resistant prostate cancer. N Engl J Med 2010; 363: 411–22.

43 Yu JS, Liu G, Ying H, Yong WH, Black KL, Wheeler CJ. Vaccination with tumor lysate-pulsed dendritic cells elicits antigen-specifi c, cytotoxic T-cells in patients with malignant glioma. Cancer Res 2004; 64: 4973–79.

44 Niu H, Dong Z, Dong F, Zhang T, Lei T, Xue D. Experimental and clinical research of dendritic cell and syngeneic immunotherapy of brain glioma. Chinese-German J Clin Oncol 2004; 3: 147–50.

45 Liau LM, Prins RM, Kiertscher SM, et al. Dendritic cell vaccination in glioblastoma patients induces systemic and intracranial T-cell responses modulated by the local central nervous system tumor microenvironment. Clin Cancer Res 2005; 11: 5515–25.

46 Yamanaka R, Homma J, Yajima N, et al. Clinical evaluation of dendritic cell vaccination for patients with recurrent glioma: results of a clinical phase I/II trial. Clin Cancer Res 2005; 11: 4160–67.

47 De Vleeschouwer S, Fieuws S, Rutkowski S, et al. Postoperative adjuvant dendritic cell-based immunotherapy in patients with relapsed glioblastoma multiforme. Clin Cancer Res 2008; 14: 3098–104.

48 Sampson JH, Archer GE, Mitchell DA, et al. An epidermal growth factor receptor variant III-targeted vaccine is safe and immunogenic in patients with glioblastoma multiforme. Mol Cancer Ther 2009; 8: 2773–79.

49 Ardon H, Van Gool S, Lopes IS, et al. Integration of autologous dendritic cell-based immunotherapy in the primary treatment for patients with newly diagnosed glioblastoma multiforme: a pilot study. J Neurooncol 2010; 99: 261–72.

50 Chang CN, Huang YC, Yang DM, et al. A phase I/II clinical trial investigating the adverse and therapeutic eff ects of a postoperative autologous dendritic cell tumor vaccine in patients with malignant glioma. J Clin Neurosci 2011; 18: 1048–54.

51 Fadul CE, Fisher JL, Hampton TH, et al. Immune response in patients with newly diagnosed glioblastoma multiforme treated with intranodal autologous tumor lysate-dendritic cell vaccination after radiation chemotherapy. J Immunother 2011; 34: 382–89.

52 Prins RM, Soto H, Konkankit V, et al. Gene expression profi le correlates with T-cell infi ltration and relative survival in glioblastoma patients vaccinated with dendritic cell immunotherapy. Clin Cancer Res 2011; 17: 1603–15.

53 Ardon H, Van Gool SW, Verschuere T, et al. Integration of autologous dendritic cell-based immunotherapy in the standard of care treatment for patients with newly diagnosed glioblastoma: results of the HGG-2006 phase I/II trial. Cancer Immunol Immunother 2012; 61: 2033–44.

54 Cho DY, Yang WK, Lee HC, et al. Adjuvant immunotherapy with whole-cell lysate dendritic cells vaccine for glioblastoma multiforme: a phase II clinical trial. World Neurosurg 2012; 77: 736–44.

55 Jie X, Hua L, Jiang W, Feng F, Feng G, Hua Z. Clinical application of a dendritic cell vaccine raised against heat-shocked glioblastoma. Cell Biochem Biophys 2012; 62: 91–99.


Review

56 Valle RD, de Cerio AL, Inoges S, et al. Dendritic cell vaccination in glioblastoma after fl uorescence-guided resection. World J Clin Oncol 2012; 3: 142–49.

57 Vik-Mo EO, Nyakas M, Mikkelsen BV, et al. Therapeutic vaccination against autologous cancer stem cells with mRNA-transfected dendritic cells in patients with glioblastoma. Cancer Immunol Immunother 2013; 62: 1499–509.

58 Su Z, Dannull J, Heiser A, et al. Immunological and clinical responses in metastatic renal cancer patients vaccinated with tumor RNA-transfected dendritic cells. Cancer Res 2003; 63: 2127–33.

59 Kim JH, Lee Y, Bae Y-S, et al. Phase I/II study of immunotherapy using autologous tumor lysate-pulsed dendritic cells in patients with metastatic renal cell carcinoma. Clin Immunol 2007; 125: 257–67.

60 Berntsen A, Trepiakas R, Wenandy L, et al. Therapeutic dendritic cell vaccination of patients with metastatic renal cell carcinoma: a clinical phase 1/2 trial. J Immunother 2008; 31: 771–80.

61 Schwaab T, Schwarzer A, Wolf B, et al. Clinical and immunologic eff ects of intranodal autologous tumor lysate-dendritic cell vaccine with Aldesleukin (interleukin 2) and IFN-alpha2a therapy in metastatic renal cell carcinoma patients. Clin Cancer Res 2009; 15: 4986–92.

62 Amin A, Dudek A, Logan T, et al. Prolonged survival with personalized immunotherapy (AGS-003) in combination with sunitinib in unfavorable risk metastatic RCC (mRCC). Proc Am Soc Clin Oncol 2013; 31 (suppl 6): abstr 357.

63 American Society of Clinical Oncology. Defi ning clinically meaningful outcomes: ASCO recommendations to raise the bar for clinical trials. 2013. http://www.asco.org/sites/www.asco.org/fi les/asco_meaningful_outcomes_draft_for_website_-_05_13_13_0.pdf (accessed May 8, 2014).

64 Sheikh NA, Petrylak D, Kantoff PW, et al. Sipuleucel-T immune parameters correlate with survival: an analysis of the randomized phase 3 clinical trials in men with castration-resistant prostate cancer. Cancer Immunol Immunother 2013; 62: 137–47.

65 Johnson JR, Williams G, Pazdur R. End points and United States Food and Drug Administration approval of oncology drugs. J Clin Oncol 2003; 21: 1404–11.

66 Sharma P, Wagner K, Wolchok JD, Allison JP. Novel cancer immunotherapy agents with survival benefi t: recent successes and next steps. Nat Rev Cancer 2011; 11: 805–12.

67 Escudier B, Eisen T, Stadler WM, et al, and the TARGET Study Group. Sorafenib in advanced clear-cell renal-cell carcinoma. N Engl J Med 2007; 356: 125–34.

68 Escudier B, Eisen T, Stadler WM, et al. Sorafenib for treatment of renal cell carcinoma: fi nal effi cacy and safety results of the phase III treatment approaches in renal cancer global evaluation trial. J Clin Oncol 2009; 27: 3312–18.

69 Wolchok JD, Hoos A, O’Day S, et al. Guidelines for the evaluation of immune therapy activity in solid tumors: immune-related response criteria. Clin Cancer Res 2009; 15: 7412–20.

70 Hoos A. Evolution of end points for cancer immunotherapy trials. Ann Oncol 2012; 23 (suppl 8): viii 47–52.

71 Beer TM, Bernstein GT, Corman JM, et al. Randomized trial of autologous cellular immunotherapy with sipuleucel-T in androgen-dependent prostate cancer. Clin Cancer Res 2011; 17: 4558–67.

72 Di Lorenzo G, Buonerba C, Kantoff PW. Immunotherapy for the treatment of prostate cancer. Nat Rev Clin Oncol 2011; 8: 551–61.

73 Stein WD, Gulley JL, Schlom J, et al. Tumor regression and growth rates determined in fi ve intramural NCI prostate cancer trials: the growth rate constant as an indicator of therapeutic effi cacy. Clin Cancer Res 2011; 17: 907–17.

74 de Vries IJM, Lesterhuis WJ, Scharenborg NM, et al. Maturation of dendritic cells is a prerequisite for inducing immune responses in advanced melanoma patients. Clin Cancer Res 2003; 9: 5091–100.

75 Okada H, Kalinski P, Ueda R, et al. Induction of CD8+ T-cell responses against novel glioma-associated antigen peptides and clinical activity by vaccinations with alpha-type 1 polarized dendritic cells and polyinosinic-polycytidylic acid stabilized by lysine and carboxymethylcellulose in patients with recurrent malignant glioma. J Clin Oncol 2011; 29: 330–36.

76 Carreno BM, Becker-Hapak M, Huang A, et al. IL-12p70-producing patient DC vaccine elicits Tc1-polarized immunity. J Clin Invest 2013; 123: 3383–94.

77 Ueno H, Schmitt N, Klechevsky E, et al. Harnessing human dendritic cell subsets for medicine. Immunol Rev 2010; 234: 199–212.

78 Romano E, Rossi M, Ratzinger G, et al. Peptide-loaded Langerhans cells, despite increased IL15 secretion and T-cell activation in vitro, elicit antitumor T-cell responses comparable to peptide-loaded monocyte-derived dendritic cells in vivo. Clin Cancer Res 2011; 17: 1984–97.

79 Anguille S, Lion E, Van den Bergh J, et al. Interleukin-15 dendritic cells as vaccine candidates for cancer immunotherapy. Hum Vaccin Immunother 2013; 9: 1956–61.

80 Boullart AC, Aarntzen EH, Verdijk P, et al. Maturation of monocyte-derived dendritic cells with Toll-like receptor 3 and 7/8 ligands combined with prostaglandin E2 results in high interleukin-12 production and cell migration. Cancer Immunol Immunother 2008; 57: 1589–97.

81 Fujita M, Zhu X, Ueda R, et al. Eff ective immunotherapy against murine gliomas using type 1 polarizing dendritic cells--signifi cant roles of CXCL10. Cancer Res 2009; 69: 1587–95.

82 Pierret L, Wilgenhof S, Corthals J, Roelandt T, Thielemans K, Neyns B. Correlation between prior therapeutic dendritic cell vaccination and the outcome of patients with metastatic melanoma treated with ipilimumab. Proc Am Soc Clin Oncol 2009; 27 (suppl): abstr e20006.

83 Ribas A, Comin-Anduix B, Chmielowski B, et al. Dendritic cell vaccination combined with CTLA4 blockade in patients with metastatic melanoma. Clin Cancer Res 2009; 15: 6267–76.

84 Hamid O, Robert C, Daud A, et al. Safety and tumor responses with lambrolizumab (anti-PD-1) in melanoma. N Engl J Med 2013; 369: 134–44.

85 Wolchok JD, Kluger H, Callahan MK, et al. Nivolumab plus ipilimumab in advanced melanoma. N Engl J Med 2013; 369: 122–33.

86 Smits EL, Ponsaerts P, Berneman ZN, Van Tendeloo VF. The use of TLR7 and TLR8 ligands for the enhancement of cancer immunotherapy. Oncologist 2008; 13: 859–75.

87 Whiteside TL. Inhibiting the inhibitors: evaluating agents targeting cancer immunosuppression. Expert Opin Biol Ther 2010; 10: 1019–35.

88 Shimizu K, Fields RC, Giedlin M, Mulé JJ. Systemic administration of interleukin 2 enhances the therapeutic effi cacy of dendritic cell-based tumor vaccines. Proc Natl Acad Sci USA 1999; 96: 2268–73.

89 Escobar A, López M, Serrano A, et al. Dendritic cell immunizations alone or combined with low doses of interleukin-2 induce specifi c immune responses in melanoma patients. Clin Exp Immunol 2005; 142: 555–68.

90 Redman BG, Chang AE, Whitfi eld J, et al. Phase Ib trial assessing autologous, tumor-pulsed dendritic cells as a vaccine administered with or without IL-2 in patients with metastatic melanoma. J Immunother 2008; 31: 591–98.

91 Mirza N, Fishman M, Fricke I, et al. All-trans-retinoic acid improves diff erentiation of myeloid cells and immune response in cancer patients. Cancer Res 2006; 66: 9299–307.

92 Zitvogel L, Apetoh L, Ghiringhelli F, André F, Tesniere A, Kroemer G. The anticancer immune response: indispensable for therapeutic success? J Clin Invest 2008; 118: 1991–2001.

93 Ridolfi L, Petrini M, Granato AM, et al. Low-dose temozolomide before dendritic-cell vaccination reduces (specifi cally) CD4+CD25++Foxp3+ regulatory T-cells in advanced melanoma patients. J Transl Med 2013; 11: 135.

94 Chen G, Emens LA. Chemoimmunotherapy: reengineering tumor immunity. Cancer Immunol Immunother 2013; 62: 203–16.

95 Wang LX, Li R, Yang G, et al. Interleukin-7-dependent expansion and persistence of melanoma-specifi c T cells in lymphodepleted mice lead to tumor regression and editing. Cancer Res 2005; 65: 10569–77.

96 Kandalaft LE, Powell DJ Jr, Chiang CL, et al. Autologous lysate-pulsed dendritic cell vaccination followed by adoptive transfer of vaccine-primed ex vivo co-stimulated T cells in recurrent ovarian cancer. OncoImmunology 2013; 2: e22664.

97 Schlom J. Therapeutic cancer vaccines: current status and moving forward. J Natl Cancer Inst 2012; 104: 599–613.


Review

98 Jacobs JF, Nierkens S, Figdor CG, de Vries IJ, Adema GJ. Regulatory T cells in melanoma: the fi nal hurdle towards eff ective immunotherapy? Lancet Oncol 2012; 13: e32–42.

99 Jacobs JF, Punt CJ, Lesterhuis WJ, et al. Dendritic cell vaccination in combination with anti-CD25 monoclonal antibody treatment: a phase I/II study in metastatic melanoma patients. Clin Cancer Res 2010; 16: 5067–78.

100 Dannull J, Su Z, Rizzieri D, et al. Enhancement of vaccine-mediated antitumor immunity in cancer patients after depletion of regulatory T cells. J Clin Invest 2005; 115: 3623–33.

101 Morse MA, Hobeika AC, Osada T, et al. Depletion of human regulatory T cells specifi cally enhances antigen-specifi c immune responses to cancer vaccines. Blood 2008; 112: 610–18.

102 Baur AS, Lutz MB, Schierer S, et al. Denileukin diftitox (ONTAK) induces a tolerogenic phenotype in dendritic cells and stimulates survival of resting Treg. Blood 2013; 122: 2185–94.

103 Yamada Y, Aoyama A, Tocco G, et al. Diff erential eff ects of denileukin diftitox IL-2 immunotoxin on NK and regulatory T cells in nonhuman primates. J Immunol 2012; 188: 6063–70.

104 Radojcic V, Bezak KB, Skarica M, et al. Cyclophosphamide resets dendritic cell homeostasis and enhances antitumor immunity through eff ects that extend beyond regulatory T cell elimination. Cancer Immunol Immunother 2010; 59: 137–48.

105 Heine A, Held SA, Bringmann A, Holderried TA, Brossart P. Immunomodulatory eff ects of anti-angiogenic drugs. Leukemia 2011; 25: 899–905.

106 Sakamaki I, Kwak LW, Cha SC, et al. Lenalidomide enhances the protective eff ect of a therapeutic vaccine and reverses immune suppression in mice bearing established lymphomas. Leukemia 2014; 28: 329–37.

107 Najjar YG, Finke JH. Clinical perspectives on targeting of myeloid derived suppressor cells in the treatment of cancer. Front Oncol 2013; 3: 49.

108 Poschke I, Mao Y, Adamson L, Salazar-Onfray F, Masucci G, Kiessling R. Myeloid-derived suppressor cells impair the quality of dendritic cell vaccines. Cancer Immunol Immunother 2012; 61: 827–38.

109 Fujita M, Kohanbash G, Fellows-Mayle W, et al. COX-2 blockade suppresses gliomagenesis by inhibiting myeloid-derived suppressor cells. Cancer Res 2011; 71: 2664–74.

110 Schilling B, Sucker A, Griewank K, et al. Vemurafenib reverses immunosuppression by myeloid derived suppressor cells. Int J Cancer 2013; 133: 1653–63.

111 Knight DA, Ngiow SF, Li M, et al. Host immunity contributes to the anti-melanoma activity of BRAF inhibitors. J Clin Invest 2013; 123: 1371–81.

112 Ott PA, Henry T, Baranda SJ, et al. Inhibition of both BRAF and MEK in BRAF(V600E) mutant melanoma restores compromised dendritic cell (DC) function while having diff erential direct eff ects on DC properties. Cancer Immunol Immunother 2013; 62: 811–22.

113 Gulley JL, Madan RA, Schlom J. Impact of tumour volume on the potential effi cacy of therapeutic vaccines. Curr Oncol 2011; 18: e150–57.

114 Van Tendeloo VF, Van de Velde A, Van Driessche A, et al. Induction of complete and molecular remissions in acute myeloid leukemia by Wilms’ tumor 1 antigen-targeted dendritic cell vaccination. Proc Natl Acad Sci USA 2010; 107: 13824–29.

115 Anguille S, Willemen Y, Lion E, Smits EL, Berneman ZN. Dendritic cell vaccination in acute myeloid leukemia. Cytotherapy 2012; 14: 647–56.

116 Gabrilovich DI. Combination of chemotherapy and immunotherapy for cancer: a paradigm revisited. Lancet Oncol 2007; 8: 2–3.

117 Wheeler CJ, Das A, Liu G, Yu JS, Black KL. Clinical responsiveness of glioblastoma multiforme to chemotherapy after vaccination. Clin Cancer Res 2004; 10: 5316–26.

118 Bracci L, Schiavoni G, Sistigu A, Belardelli F. Immune-based mechanisms of cytotoxic chemotherapy: implications for the design of novel and rationale-based combined treatments against cancer. Cell Death Diff er 2014; 21: 15–25.

119 Aragon-Ching JB, Williams KM, Gulley JL. Impact of androgen-deprivation therapy on the immune system: implications for combination therapy of prostate cancer. Front Biosci 2007; 12: 4957–71.

120 Kalbasi A, June CH, Haas N, Vapiwala N. Radiation and immunotherapy: a synergistic combination. J Clin Invest 2013; 123: 2756–63.

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Clinical Use of Dendrtitic Cell Vaccine