A methodological framework to enhance the clinical success of cancer immunotherapy

A mathematical model of viral oncology as an immuno-oncology instigator

We develop and analyse a mathematical model of tumour-immune interaction that explicitly incorporates heterogeneity in tumour cell cycle duration by using a distributed delay differential equation. We derive a necessary and sufficient condition for local stability of the cancer-free equilibrium in which the amount of tumour-immune interaction completely characterizes disease progression. Consistent with the immunoediting hypothesis, we show that decreasing tumour-immune interaction leads to tumour expansion. Finally, by simulating the mathematical model, we show that the strength of tumour-immune interaction determines the long-term success or failure of viral therapy.

Adverse Events Following Administration of Anti-CTLA4 Antibody Ipilimumab

Ipilimumab, a monoclonal anti-CTLA4 antibody, paved the path for promising treatments, particularly in advanced forms of numerous cancers like melanoma. By blockading CTLA-4, ipilimumab can abolish the higher binding affinity of B7 for CTLA-4, setting CD28 free to act unlimited. This blockade can result in an amplified antitumor immune response, and thereby, boosting more effective tumor regression. However, this blockage can lead to diminished self-tolerance and yielding autoimmune complications. The current review aims to describe adverse events (AEs) following the administration of ipilimumab in different cancers as every benefit comes at a cost. We will also discuss AEs in two different categories, melanoma and non-melanoma, owing to the possible shining promises in treating non-melanoma cancers. As the melanoma settings are more studied than other cancers, it might even help predict the patterns related to the other types of cancers. This similarity also might help physicians to predict adverse events and correctly manage them in non-melanoma cancers using the extensive findings reported in the more-studied melanoma settings. Recognizing the adverse events is vital since most of the adverse events could be reverted while carefully implementing guidelines. Finally, we will also describe the observed effectiveness of ipilimumab in non-melanoma cancers. This effectiveness reveals the importance of understanding the profile of adverse events in this group, even though some have not received FDA approval yet. Further clinical trials and careful systematic reviews may be required to decipher the hidden aspects of therapies with ipilimumab and its related AEs.

Improving Dendritic Cell Cancer Vaccine Potency Using RNA Interference

Dendritic cell cancer vaccines have already become a treatment modality for patients with various cancer types. However, the curative potential of this immunotherapy is limited by the existence of negative feedback mechanisms that control dendritic cells (DCs) and T-cell function. By inhibiting the expression of inhibitory factors using RNA interference technology, a new generation of DC vaccines was developed. Vaccine-stimulated T cells showed antitumor effects both in vitro and in cancer patients. Here, we describe the development and validation of a fully GMP-compliant production process of ex vivo DC cancer vaccines combined with the blockade of immunosuppressive pathways using small interfering RNAs. The protocol can be used for DC-based therapy for all cancer types.

Phase I Clinical Trial Using Autologous Ex Vivo Expanded NK Cells and Cytotoxic T Lymphocytes for Cancer Treatment in Vietnam

(1) Background: Immune cell therapy recently attracted enormous attention among scientists as a cancer treatment, but, so far, it has been poorly studied and applied in Vietnam. The aim of this study was to assess the safety of autologous immune cell therapy for treating lung, liver, and colon cancers-three prevalent cancers in Vietnam. (2) Method: This was an open-label, single-group clinical trial that included 10 patients with confirmed diagnosis of colon, liver, or lung cancer, conducted between March 2016 and December 2017. (3) Results: After 20-21 days of culture, the average number of cytotoxic T lymphocytes (CTLs) increased 488.5-fold and the average cell viability was 96.3%. The average number of natural killer cells (NKs) increased 542.5-fold, with an average viability of 95%. Most patients exhibited improved quality of life, with the majority of patients presenting a score of 1 to 2 in the Eastern Cooperative Oncology Group (ECOG) performance status (ECOG/PS) scale, a decrease in symptoms on fatigue scales, and an increase in the mean survival time to 18.7 months at the end of the study. (4) Conclusion: This method of immune cell expansion met the requirements for clinical applications in cancer treatment and demonstrated the safety of this therapy for the cancer patients in Vietnam.

Cytokines Produced by Dendritic Cells Administered Intratumorally Correlate with Clinical Outcome in Patients with Diverse Cancers

Purpose: Dendritic cells (DC) initiate adaptive immune responses through the uptake and presentation of antigenic material. In preclinical studies, intratumorally injected activated DCs (aDCs; DCVax-Direct) were superior to immature DCs in rejecting tumors from mice.Experimental Design: This single-arm, open-label phase I clinical trial evaluated the safety and efficacy of aDCs, administered intratumorally, in patients with solid tumors. Three dose levels (2 million, 6 million, and 15 million aDCs per injection) were tested using a standard 3 + 3 dose-escalation trial design. Feasibility, immunogenicity, changes to the tumor microenvironment after direct injection, and survival were evaluated. We also investigated cytokine production of aDCs prior to injection.Results: In total, 39 of the 40 enrolled patients were evaluable. The injections of aDCs were well tolerated with no dose-limiting toxicities. Increased lymphocyte infiltration was observed in 54% of assessed patients. Stable disease (SD; best response) at week 8 was associated with increased overall survival. Increased secretion of interleukin (IL)-8 and IL12p40 by aDCs was significantly associated with survival (P = 0.023 and 0.024, respectively). Increased TNFα levels correlated positively with SD at week 8 (P < 0.01).Conclusions: Intratumoral aDC injections were feasible and safe. Increased production of specific cytokines was correlated with SD and prolonged survival, demonstrating a link between the functional profile of aDCs prior to injection and patient outcomes. Clin Cancer Res; 24(16); 3845-56. ©2018 AACR.

Interim Futility Monitoring Assessing Immune Therapies With a Potentially Delayed Treatment Effect

Purpose Introduction of new immune therapies that may have a delayed beneficial effect necessitates re-evaluation of traditional clinical trial designs in oncology. A key design feature of randomized trials is interim futility monitoring, which allows stopping early if the accruing data convincingly demonstrate that the experimental treatment is detrimental or is unlikely to be shown superior to the standard treatment. The appropriateness of futility monitoring is frequently questioned when the effect of the experimental treatment may be delayed (eg, in trials of many immune agents). We examine the advisability of using futility monitoring when there is potential for a delayed treatment effect and make recommendations concerning its use. Methods We evaluated the loss of statistical power when using some common futility interim monitoring rules and a new proposed conservative rule via simulation under varying amounts of treatment-effect delay and varying accrual periods. We also considered scenarios where the experimental treatment starts out being worse than the standard treatment but ends up being better, as may sometimes be the case when an immune therapy is compared with an active standard therapy. Results Some standard methods of futility monitoring can result in an unacceptable loss of power when there is a delayed treatment effect, especially if the accrual period is rapid or the experimental treatment is initially worse. The proposed conservative futility rule has a negligible loss of power in the situations considered. Conclusion Although care must be taken with the choice of futility monitoring when there is a delayed treatment effect, inclusion of appropriate rules can reduce the exposure of patients to ineffective therapies without reducing the probability of correctly identifying effective treatments.

Immuno-oncology Trial Endpoints: Capturing Clinically Meaningful Activity

Immuno-oncology (I-O) has required a shift in the established paradigm of toxicity and response assessment in clinical research. The design and interpretation of cancer clinical trials has been primarily driven by conventional toxicity and efficacy patterns observed with chemotherapy and targeted agents, which are insufficient to fully inform clinical trial design and guide therapeutic decisions in I-O. Responses to immune-targeted agents follow nonlinear dose-response and dose-toxicity kinetics mandating the development of novel response evaluation criteria. Biomarker-driven surrogate endpoints may better capture the mechanism of action and biological response to I-O agents and could be incorporated prospectively in early-phase I-O clinical trials. While overall survival remains the gold standard for evaluation of clinical efficacy of I-O agents in late-phase clinical trials, exploration of potential novel surrogate endpoints such as objective response rate and milestone survival is to be encouraged. Patient-reported outcomes should also be assessed to help redefine endpoints for I-O clinical trials and drive more efficient drug development. This paper discusses endpoints used in I-O trials to date and potential optimal endpoints for future early- and late-phase clinical development of I-O therapies.

Do immune checkpoint inhibitors need new studies methodology?

Immune checkpoint inhibitors (ICI) have widely reshaped the treatment paradigm of advanced cancer patients. Although multiple studies are currently evaluating these drugs as monotherapies or in combination, the choice of the most accurate statistical methods, endpoints and clinical trial designs to estimate the benefit of ICI remains an unsolved methodological issue. Considering the unconventional patterns of response or progression [i.e., pseudoprogression, hyperprogression (HPD)] observed with ICI, the application in clinical trials of novel response assessment tools (i.e., iRECIST) able to capture delayed benefit of immunotherapies and/or to quantify tumor dynamics and kinetics over time is an unmet clinical need. In addition, the proportional hazard model and the conventional measures of survival [i.e., median overall or progression free survival (PFS) and hazard ratios (HR)] might usually result inadequate in the estimation of the long-term benefit observed with ICI. For this reason, innovative methodologies such as milestone analysis, restricted mean survival time (RMST), parametric models (i.e., Weibull distribution, weighted log rank test), should be systematically investigated in clinical trials in order to adequately quantify the fraction of patients who are "cured", represented by the tails of the survival curves. Regarding predictive biomarkers, in particular PD-L1 expression, the integration and harmonization of the existing assays are urgently needed to provide clinicians with reliable diagnostic tests and to improve patient selection for immunotherapy. Finally, developing original and high-quality study designs, such as adaptive or basket biomarker enriched clinical trials, included in large collaborative platforms with multiple active sites and cross-sector collaboration, represents the successful strategy to optimally assess the benefit of ICI in the next future.

End points and statistical considerations in immuno-oncology trials: impact on multiple myeloma

Unlike conventional cancer treatment, immuno-oncology therapies are commonly associated with delayed clinical benefit and durable responses, as seen with immuno-oncology therapies for multiple myeloma (MM). Therefore, a longer-term approach to immuno-oncology data assessment is required. Appropriate study designs, end points and statistical methods are essential for evaluating immuno-oncology therapies to assess treatment outcomes, and may better accommodate immuno-oncology clinical trial data. In addition to conventional end points including median progression-free survival (PFS) and overall survival (OS), end points such as hazard ratios for PFS and OS over time, PFS and OS landmark analyses beyond the median, and immune-response end points might provide better indications of the efficacy of immuno-oncology therapies. Long-term data with these agents will allow better prediction of outcomes in MM.

A comprehensive review of immunotherapies in prostate cancer

Prostate cancer is the second most common malignant neoplasm in men worldwide and the fifth cause of cancer-related death. Although multiple new agents have been approved for metastatic castration resistant prostate cancer over the last decade, it is still an incurable disease. New strategies to improve cancer control are needed and agents targeting the immune system have shown encouraging results in many tumor types. Despite being attractive for immunotherapies due to the expression of various tumor associated antigens, the microenvironment in prostate cancer is relatively immunosuppressive and may be responsible for the failures of various agents targeting the immune system in this disease. To date, sipuleucel-T is the only immunotherapy that has shown significant clinical efficacy in this setting, although the high cost and potential trial flaws have precluded its widespread incorporation into clinical practice. Issues with patient selection and trial design may have contributed to the multiple failures of immunotherapy in prostate cancer and provides an opportunity to tailor future studies to evaluate these agents more accurately. We have reviewed all the completed immune therapy trials in prostate cancer and highlight important considerations for the next generation of clinical trials.

Quantifying in vivo murine antigen-specific T cell responses without requirement for prior knowledge of antigen identity

Extracorporeal Photochemotherapy (ECP) is a widely applied anti-cancer immunotherapy for patients with cutaneous T cell lymphoma (CTCL). By using apoptotic malignant cells as a source of patient-specific tumor antigen, it enables clinically relevant and curative anti-CTCL immunity, with potential efficacy in other tumors. Currentmethods to track patient-specific responses are tedious, and new methods are needed to assess putative global immunity. We developed a clinically practical method to assess antigen-specific T cell activation that does not rely on knowledge of the particular antigen, thereby eliminating the requirement for patient-specific reagents. In the OT-I transgenic murine system, we quantified calcium flux to reveal early T cell engagement by antigen presenting cells constitutively displaying a model antigenic peptide, ovalbumin (OVA)-derived SIINFEKL. We detected calcium flux in OVA-specific T cells, triggered by specific T cell receptor engagement by SIINFEKL peptide-loaded DC. This approach led to sensitive detection of antigen-specific calcium flux (ACF) down to a peptide-loading concentration of ∼10^-3uM and at a frequency of ∼0.1% OT-I cells among wild-type (WT), non-responding cells. Antigen-specific T cells were detected in spleen, lymph nodes, and peripheral blood after adoptive transfer into control recipient mice. Methods like this for assessing therapeutic response are lacking in patients currently on immune-based therapies, such as ECP, where assessment of clinical response is made by delayed measurement of the size of the malignant clone. These findings suggest an early, practical way to measure therapeutically-induced anti-tumor responses in ECP-treated patients that have been immunized against their malignant cells.

Diversification of Antitumour Immunity in a Patient with Metastatic Melanoma Treated with Ipilimumab and an IDO-Silenced Dendritic Cell Vaccine

Indoleamine 2,3-dioxygenase (IDO) expression in dendritic cells (DCs) inhibits T-cell activation and promotes T-cell differentiation into regulatory T-cells. Moreover, IDO expression promotes resistance to immunotherapies targeting immune checkpoints such as the cytotoxic T lymphocyte antigen-4 (CTLA-4). Here, a patient with metastatic melanoma pretreated with ipilimumab, an anti-CTLA-4 blocking antibody, was vaccinated with IDO-silenced DCs cotransfected with mRNA for survivin or hTERT tumour antigens. During vaccination, T-cell responses to survivin and hTERT tumour antigens were generated, and a certain degree of clinical benefit was achieved, with a significant reduction in lung, liver, and skin metastases, along with a better performance status. T-cell responses against MART-1 and NY-ESO-1 tumour antigens were also detected in the peripheral blood. The patient also mounted an antibody response to several melanoma proteins, indicating diversification of the antitumour immunity in this patient. The identification of such serum antibody-reacting proteins could facilitate the discovery of tumour neoantigens.

Reprogramming Immune Response With Capsid-Optimized AAV6 Vectors for Immunotherapy of Cancer

In the current studies we generated novel capsid-optimized adeno-associated virus (AAV) serotype 6 (AAV6) vectors expressing a tumor-associated antigen, and assessed their ability to activate a protective T-cell response in an animal model. First, we showed that specific mutations in the AAV6 capsid increase the transduction efficiency of these vectors in mouse bone marrow-derived dendritic cells in vitro for approximately 5-fold compared with the wild-type (WT) AAV6 vectors. Next, we evaluated the ability of the mutant AAV6 vectors to initiate specific T-cell clone proliferation in vivo. Our data indicate that the intramuscular administration of AAV6-S663V+T492V vectors expressing ovalbumin (OVA) led to a strong activation (approximately 9%) of specific T cells in peripheral blood compared with AAV6-WT treated animals (<1%). These OVA-specific T cells have a superior killing ability against mouse prostate cancer cell line RM1 stably expressing the OVA antigen when propagated in vitro. Finally, we evaluated the ability of capsid-optimized AAV6-S663V+T492V vectors to initiate a protective anticancer immune response in vivo. Our results document the suppression of subcutaneous tumor growth in animals immunized with AAV6-S663V+T492V vectors expressing prostatic acid phosphatase (PAP) for approximately 4 weeks in comparison with 1 week and 2 weeks for the negative controls, AAV6-EGFP, and AAV6-WT-PAP treated mice, respectively. These studies suggest that successful inhibition of tumor growth in an animal model would set the stage for potential clinical application of the capsid-optimized AAV6-S663V+T492V vectors.

Development of immuno-oncology drugs - from CTLA4 to PD1 to the next generations

Since the regulatory approval of ipilimumab in 2011, the field of cancer immunotherapy has been experiencing a renaissance. This success is based on progress in both preclinical and clinical science, including the development of new methods of investigation. Immuno-oncology has become a sub-specialty within oncology owing to its unique science and its potential for substantial and long-term clinical benefit. Immunotherapy agents do not directly attack the tumour but instead mobilize the immune system - this can be achieved through various approaches that utilize adaptive or innate immunity. Therefore, immuno-oncology drug development encompasses a broad range of agents, including antibodies, peptides, proteins, small molecules, adjuvants, cytokines, oncolytic viruses, bi-specific molecules and cellular therapies. This Perspective summarizes the recent history of cancer immunotherapy, including the factors that led to its success, provides an overview of novel drug-development considerations, summarizes three generations of immunotherapies that have been developed since 2011 and, thus, illustrates the breadth of opportunities these new generations of immunotherapies represent.

A quantitative analysis of therapeutic cancer vaccines in phase 2 or phase 3 trial

Despite the progress that has been made in other forms of cancer therapy, Provenge® (Sipuleucel-T) is the only FDA-approved vaccine for the treatment of cancer. To understand the current landscape of therapeutic oncology vaccines we performed a quantitative analysis of phase 2 and phase 3 therapeutic cancer vaccine trials. We highlight shifts in trends for the vaccine platforms examined, common adjuvant use, target indications, antibody or treatment combinations between past and recent trials as well as discuss the relationship between these trends and ratio between the number of phase 3: phase 2 for different vaccine platforms. Despite the poor success rate in vaccine approvals, registration of phase 3 trials between 2010 and 2014 were stable indicating continued investment and efforts towards development of immunotherapeutic vaccines.

Big opportunities for small molecules in immuno-oncology

The regulatory approval of ipilimumab (Yervoy) in 2011 ushered in a new era of cancer immunotherapies with durable clinical effects. Most of these breakthrough medicines are monoclonal antibodies that block protein-protein interactions between T cell checkpoint receptors and their cognate ligands. In addition, genetically engineered autologous T cell therapies have also recently demonstrated significant clinical responses in haematological cancers. Conspicuously missing from this class of therapies are traditional small-molecule drugs, which have previously served as the backbone of targeted cancer therapies. Modulating the immune system through a small-molecule approach offers several unique advantages that are complementary to, and potentially synergistic with, biologic modalities. This Review highlights immuno-oncology pathways and mechanisms that can be best or solely targeted by small-molecule medicines. Agents aimed at these mechanisms--modulation of the immune response, trafficking to the tumour microenvironment and cellular infiltration--are poised to significantly extend the scope of immuno-oncology applications and enhance the opportunities for combination with tumour-targeted agents and biologic immunotherapies.

A rationally designed combined treatment with an alphavirus-based cancer vaccine, sunitinib and low-dose tumor irradiation completely blocks tumor development

The clinical efficacy of therapeutic cancer vaccines remains limited. For effective immunotherapeutic responses in cancer patients, multimodal approaches capable of both inducing antitumor immune responses and bypassing tumor-mediated immune escape seem essential. Here, we report on a combination therapy comprising sunitinib (40 mg/kg), single low-dose (14 Gy) tumor irradiation and immunization with a therapeutic cancer vaccine based on a Semliki Forest virus vector encoding the oncoproteins E6 and E7 of human papillomavirus (SFVeE6,7). We previously demonstrated that either low-dose irradiation or sunitinib in single combination with SFVeE6,7 immunizations enhanced the intratumoral ratio of antitumor effector cells to myeloid-derived suppressor cells (MDSCs). On the basis of these results we designed a triple treatment combinatorial regimen. The trimodal sunitinib, low-dose irradiation and SFVeE6,7 immunization therapy resulted in stronger intratumoral MDSC depletion than sunitinib alone. Concomitantly, the highest levels of intratumoral E7-specific CD8⁺ T cells were attained after triple treatment. Approximately 75% of these cells were positive for the early activation marker CD69. The combination of sunitinib, low-dose tumor irradiation and SFVeE6,7 immunization dramatically changed the intratumoral immune compartment. Whereas control tumors contained 0.02 E7-specific CD8⁺ T cells per MDSC, triple treatment tumors contained more than 200 E7-specific CD8⁺ T cells per MDSC, a 10,000-fold increased ratio. As a result, the triple treatment strongly enhanced the immunotherapeutic antitumor effect, blocking tumor development altogether and leading to 100% tumor-free survival of tumor-bearing mice. This study demonstrates that this multimodal approach elicits superior antitumor effects and should be considered for clinical applications.

Approaches to improve development methods for therapeutic cancer vaccines

Therapeutic cancer vaccines are an immunotherapy that amplify or induce an active immune response against tumors. Notably, limitations in the methodology for existing anti-cancer drugs may subsist while applying them to cancer vaccine therapy. A retrospective analysis was performed using information obtained from ClinicalTrials.gov, PubMed, and published articles. Our research evaluated the optimal methodologies for therapeutic cancer vaccines based on (1) patient populations, (2) immune monitoring, (3) tumor response evaluation, and (4) supplementary therapies. Failure to optimize these methodologies at an early phase may impact development at later stages; thus, we have proposed some points to be considered during the early phase. Moreover, we compared our proposal with the guidance for industry issued by the US Food and Drug Administration in October 2011 entitled "Clinical Considerations for Therapeutic Cancer Vaccines". Consequently, while our research was aligned with the guidance, we hope it provides further insights in order to predict the risks and benefits and facilitate decisions for a new technology. We identified the following points for consideration: (1) include in the selection criteria the immunological stage with a prognostic value, which is as important as the tumor stage; (2) select immunological assays such as phenotype analysis of lymphocytes, based on their features and standardize assay methods; (3) utilize optimal response criteria for immunotherapy in therapeutic cancer vaccine trials; and (4) consider supplementary therapies, including immune checkpoint inhibitors, for future therapeutic cancer vaccines.

Immunosuppressive factor blockade in dendritic cells via siRNAs results in objective clinical responses

Over the past decade, immunotherapy has emerged as a promising new form of cancer treatment with the potential to eradicate tumor metastasis. However, its curative potential is in general limited by the existence of negative feedback mechanisms that control dendritic cells (DCs) and T-cell activation. For clinically effective immunity, there is a need of inhibiting the expression of these immune suppressors. This could enhance the activation of DCs, T cells, and natural killer cells, and might be beneficial for cancer immunotherapy. Among the immune inhibitory molecules expressed by DCs is indoleamine 2,3-dioxygenase (IDO), an enzyme that conveys immunosuppressive effects by degrading tryptophan, an essential amino acid required for T-cell proliferation and survival. Depletion of tryptophan by IDO-positive DCs induces T-cell apoptosis and the conversion of naïve CD4+ T cells into regulatory T cells that further suppress antitumor immunity. Herein, we describe a protocol for in vitro synthesis of small interfering RNA against IDO and other immunosuppressive factors such as interleukin-10 and programmed cell death-1 ligands in order to reverse immune suppression mediated by DCs. Vaccination with IDO-silenced DC vaccines enhanced immune responses and antitumor immunity in cancer patients.

[Targeting p16(INK4a) by therapeutic vaccination : Concept and status of clinical investigations in HPV-associated head and neck cancers]

BACKGROUND

Up to 70% of oropharyngeal cancers are attributable to human papillomavirus (HPV) infection; however, a therapy specific for patients with HPV-associated cancers is currently not available. Overexpression of the viral oncogenes E6 and E7 results in cellular alterations that represent interesting targets for novel therapies. One consequence of E6/E7 overexpression is strong expression of the cellular protein p16(INK4a). The elimination of p16(INK4a)-expressing tumor cells by the immune system could be achieved through a therapeutic p16(INK4a) vaccine.

OBJECTIVE

The current article provides an overview of HPV-associated head and neck cancers and the associated p16(INK4a) expression. Based on this overview, the concept and status of the clinical investigation of therapeutic p16(INK4a) vaccination is described.

MATERIAL AND METHODS

In addition to discussing published literature, a clinical study is described. In this phase I/IIa study, patients with advanced HPV-associated p16(INK4a)-expressing tumors were vaccinated with a p16(INK4a) peptide.

RESULTS

HPV-associated head and neck cancers continuously display strong overexpression of the cellular protein p16(INK4a). Vaccination with p16(INK4a) could represent a novel therapy for patients with HPV-associated carcinomas.

CONCLUSION

Further studies will evaluate the clinical efficacy of therapeutic p16(INK4a) vaccination. Combinations with other immunotherapeutic approaches are interesting considering the modulating role of the immune system, particularly in HPV-associated tumors.

Personalizing immunotherapy: Balancing predictability and precision

Despite great expectations and research efforts, anticancer immunotherapy has not yet become a definitive cure. Perhaps, this is because past reductionist approaches were too simplistic for the patient-specific complex system of co-evolving tumor cells and host immunity. Recent efforts based on a systems-based approach promise improved clinical outcomes engendered by a dynamic modification of personalized therapeutic regimens.

Therapeutic vaccines for cancer: an overview of clinical trials

The therapeutic potential of host-specific and tumour-specific immune responses is well recognized and, after many years, active immunotherapies directed at inducing or augmenting these responses are entering clinical practice. Antitumour immunization is a complex, multi-component task, and the optimal combinations of antigens, adjuvants, delivery vehicles and routes of administration are not yet identified. Active immunotherapy must also address the immunosuppressive and tolerogenic mechanisms deployed by tumours. This Review provides an overview of new results from clinical studies of therapeutic cancer vaccines directed against tumour-associated antigens and discusses their implications for the use of active immunotherapy.

Immunologic response to the survivin-derived multi-epitope vaccine EMD640744 in patients with advanced solid tumors

PURPOSE

Survivin is a member of the inhibitor-of-apoptosis family. Essential for tumor cell survival and overexpressed in most cancers, survivin is a promising target for anti-cancer immunotherapy. Immunogenicity has been demonstrated in multiple cancers. Nonetheless, few clinical trials have demonstrated survivin-vaccine-induced immune responses.

EXPERIMENTAL DESIGN

This phase I trial was conducted to test whether vaccine EMD640744, a cocktail of five HLA class I-binding survivin peptides in Montanide(®) ISA 51 VG, promotes anti-survivin T-cell responses in patients with solid cancers. The primary objective was to compare immunologic efficacy of EMD640744 at doses of 30, 100, and 300 μg. Secondary objectives included safety, tolerability, and clinical efficacy.

RESULTS

In total, 49 patients who received ≥2 EMD640744 injections with available baseline- and ≥1 post-vaccination samples [immunologic-diagnostic (ID)-intention-to-treat] were analyzed by ELISpot- and peptide/MHC-multimer staining, revealing vaccine-activated peptide-specific T-cell responses in 31 patients (63 %). This cohort included the per study protocol relevant ID population for the primary objective, i.e., T-cell responses by ELISpot in 17 weeks following first vaccination, as well as subjects who discontinued the study before week 17 but showed responses to the treatment. No dose-dependent effects were observed. In the majority of patients (61 %), anti-survivin responses were detected only after vaccination, providing evidence for de novo induction. Best overall tumor response was stable disease (28 %). EMD640744 was well tolerated; local injection-site reactions constituted the most frequent adverse event.

CONCLUSIONS

Vaccination with EMD640744 elicited T-cell responses against survivin peptides in the majority of patients, demonstrating the immunologic efficacy of EMD640744.

Can calcium signaling be harnessed for cancer immunotherapy?

Experimental evidence shows the importance of the immune system in controlling tumor appearance and growth. Immunotherapy is defined as the treatment of a disease by inducing, enhancing or suppressing an immune response. In the context of cancer treatment, it involves breaking tolerance to a cancer-specific self-antigen and/or enhancing the existing anti-tumor immune response, be it specific or not. Part of the complexity in developing such treatment is that cancers are selected to escape adaptive or innate immune responses. These escape mechanisms are numerous and they may cumulate in one cancer. Moreover, different cancers of a same type may present different combinations of escape mechanisms. The limited success of immunotherapeutics in the clinic as stand-alone products may in part be explained by the fact that most of them only activate one facet of the immune response. It is important to identify novel methods to broaden the efficacy of immunotherapeutics. Calcium signaling is central to numerous cellular processes, leading to immune responses, cancer growth and apoptosis induced by cancer treatments. Calcium signaling in cancer therapy and control will be integrated to current cancer immunotherapy approaches. This article is part of a Special Issue entitled: Calcium Signaling in Health and Disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.

Miniaturized and high-throughput assays for analysis of T-cell immunity specific for opportunistic pathogens and HIV

Monitoring of antigen-specific T-cell responses is valuable in numerous conditions that include infectious diseases, vaccinations, and opportunistic infections associated with acquired or congenital immune defects. A variety of assays that make use of peripheral lymphocytes to test activation markers, T-cell receptor expression, or functional responses are currently available. The last group of assays calls for large numbers of functional lymphocytes. The number of cells increases with the number of antigens to be tested. Consequently, cells may be the limiting factor, particularly in lymphopenic subjects and in children, the groups that more often require immune monitoring. We have developed immunochemical assays that measure secreted cytokines in the same wells in which peripheral blood mononuclear cells (PBMC) are cultured. This procedure lent itself to miniaturization and automation. Lymphoproliferation and the enzyme-linked immunosorbent spot (ELISPOT) assay have been adapted to a miniaturized format. Here we provide examples of immune profiles and describe a comparison between miniaturized assays based on cytokine secretion or proliferation. We also demonstrate that these assays are convenient for use in testing antigen specificity in established T-cell lines, in addition to analysis of PBMC. In summary, the applicabilities of miniaturization to save cells and reagents and of automation to save time and increase accuracy were demonstrated in this study using different methodological approaches valuable in the clinical immunology laboratory.

Rationally designed capsid and transgene cassette of AAV6 vectors for dendritic cell-based cancer immunotherapy

Dendritic cell (DC)-based immunotherapy has recently demonstrated a great potential for clinical applications; however, additional progress in the methods of tumor-specific antigen delivery to DCs is necessary for the further development of anti-tumor vaccines. To this end, a capsid-optimized adeno-associated virus serotype 6 (AAV6-T492V+S663V) vector was developed by site-directed mutagenesis of surface-exposed serine (S) and threonine (T) residues, which have a critical role in intracellular trafficking of AAV vectors. This double-mutant AAV6 vector had ∼ 5-fold greater transduction efficiency in monocyte-derived DCs (moDCs) compared with wild-type (WT)-AAV6 vectors. The increase in the transduction efficiency correlated with the improved nuclear translocation of AAV6-T492V+S663V over that of the WT-AAV6 vector. Additional studies of the CD11c promoter identified critical regulatory elements that fit into the AAV expression cassette and drive EGFP expression in moDCs. Development of a chimeric promoter (chmCD11c) that contains functional modules of CD11c and a Simian virus (SV40) enhancer element dramatically increased the EGFP expression in moDCs. MoDCs transduced by the capsid-optimized AAV6 vector carrying human prostate-specific antigen (hPSA) driven by CBA (AAV6-T492V+S663V-CBA-hPSA) or chmCd11c (AAV6-T492V+S663V-chmCD11c-hPSA) generated specific T-cell clone proliferation and superior cytotoxic T lymphocytes (CTLs) with higher killing capability against human prostate adenocarcinoma cells, LNCaP, compared with WT-AAV6 induced CTLs. Taken together, these studies suggest that optimization of capsid and promoter components of AAV vectors can be a useful approach for efficient targeting of moDCs and may prove to be a promising tool for cancer immunotherapy.

Late divergence of survival curves in cancer immunotherapy trials: interpretation and implications

Late divergence of survival curves of treated patients and controls is commonly seen in successful cancer immunotherapy trials. Although late survival curve divergence may be caused by a delayed action of therapy, it may also be related to early effects of the treatment. We suggest that late survival divergence most often reflects a specific benefit of therapy for patients who suffer from a comparatively slow progression of disease. The occurrence of delayed survival curve divergence has important implications for the statistical analysis of immunotherapy trials. Thus, it leads to non-proportional hazard ratios that make commonly used statistical tests, e.g., the logrank test, suboptimal. It is therefore suggested that the statistical analysis of immunotherapy trials primarily should be based on a test that compares the survival curves at or after a prespecified, fixed, late time point.

Early thymus and activation-regulated chemokine (TARC) reduction and response following panobinostat treatment in patients with relapsed/refractory Hodgkin lymphoma following autologous stem cell transplant

Abstract In a phase 2 trial of panobinostat in 129 patients with relapsed or refractory Hodgkin lymphoma, exploratory analyses of chemokines and cytokines were prospectively performed in 109 patients to determine their association with clinical outcomes. Patients were categorized into two groups (reductions > median and reductions ≤ median) based on percentage change from baseline of log10 transformed measurements. Thymus and activation-regulated chemokine (TARC) was most strongly associated with clinical outcome. Early reduction of TARC was observed in responding patients, with the greatest reduction at cycle 1, day 15 (C1D15). Of 93 patients with C1D15 samples, there were three complete and 25 partial responses. The group with TARC reductions > median at C1D15 had more responders (18 [39%] vs. 10 [21%]), longer progression-free survival (10.6 vs. 4.9 months), shorter time to response and longer overall survival than the group with reductions ≤ median. This study is registered at www.ClinicalTrials.gov , NCT00742027.

Development of ipilimumab: a novel immunotherapeutic approach for the treatment of advanced melanoma

The immunotherapeutic agent ipilimumab has helped address a significant unmet need in the treatment of advanced melanoma. Ipilimumab is a fully human monoclonal antibody that targets cytotoxic T-lymphocyte antigen-4 (CTLA-4), thereby augmenting antitumor immune responses. After decades in which a number of clinical trials were conducted, ipilimumab was the first therapy to improve overall survival in a randomized, controlled phase III trial of patients with advanced melanoma. These results led to the regulatory approval of ipilimumab at 3 mg/kg for the treatment of unresectable or metastatic melanoma. More than 17,000 patients worldwide have received ipilimumab, either as a commercial drug at 3 mg/kg or in clinical trials and expanded access programs at different doses. Consistent with its proposed mechanism of action, the most common toxicities associated with ipilimumab therapy are inflammatory in nature. These immune-related adverse events were mostly reversible when effective treatment guidelines were followed. Importantly, long-term follow-up of patients who received ipilimumab in a phase III trial showed that 24% survived at least two years, and in phase II studies, a proportion of patients survived at least five years. Evaluation of ipilimumab is ongoing in the adjuvant setting for melanoma, and for advanced disease in nonsmall cell lung, small cell lung, prostate, ovarian, and gastric cancers.

Quality control, analysis and secure sharing of Luminex® immunoassay data using the open source LabKey Server platform

BACKGROUND

Immunoassays that employ multiplexed bead arrays produce high information content per sample. Such assays are now frequently used to evaluate humoral responses in clinical trials. Integrated software is needed for the analysis, quality control, and secure sharing of the high volume of data produced by such multiplexed assays. Software that facilitates data exchange and provides flexibility to perform customized analyses (including multiple curve fits and visualizations of assay performance over time) could increase scientists' capacity to use these immunoassays to evaluate human clinical trials.

RESULTS

The HIV Vaccine Trials Network and the Statistical Center for HIV/AIDS Research and Prevention collaborated with LabKey Software to enhance the open source LabKey Server platform to facilitate workflows for multiplexed bead assays. This system now supports the management, analysis, quality control, and secure sharing of data from multiplexed immunoassays that leverage Luminex xMAP® technology. These assays may be custom or kit-based. Newly added features enable labs to: (i) import run data from spreadsheets output by Bio-Plex Manager™ software; (ii) customize data processing, curve fits, and algorithms through scripts written in common languages, such as R; (iii) select script-defined calculation options through a graphical user interface; (iv) collect custom metadata for each titration, analyte, run and batch of runs; (v) calculate dose-response curves for titrations; (vi) interpolate unknown concentrations from curves for titrated standards; (vii) flag run data for exclusion from analysis; (viii) track quality control metrics across runs using Levey-Jennings plots; and (ix) automatically flag outliers based on expected values. Existing system features allow researchers to analyze, integrate, visualize, export and securely share their data, as well as to construct custom user interfaces and workflows.

CONCLUSIONS

Unlike other tools tailored for Luminex immunoassays, LabKey Server allows labs to customize their Luminex analyses using scripting while still presenting users with a single, graphical interface for processing and analyzing data. The LabKey Server system also stands out among Luminex tools for enabling smooth, secure transfer of data, quality control information, and analyses between collaborators. LabKey Server and its Luminex features are freely available as open source software at http://www.labkey.com under the Apache 2.0 license.

Silencing of indoleamine 2,3-dioxygenase enhances dendritic cell immunogenicity and antitumour immunity in cancer patients

Dendritic cells (DCs) are being explored as a therapeutic vaccine for cancers. However, their immunogenic potential is limited by the presence of immunosuppressive factors. Among these factors is the tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO). In this study, we have investigated the safety, immunogenicity and clinical response of IDO-silenced DC vaccine in four patients with gynecological cancers. DCs were transfected with IDO small interfering RNA and mRNA encoding human telomerase reverse transcriptase (hTERT) or survivin, two universal tumour antigens. Silencing of IDO in DCs did not affect the expression of the co-stimulatory molecules CD80 and CD86, but enhanced the expression of the CCR7 and CD40 molecules. IDO-silenced DCs showed superior potency to activate allogeneic T cells compared to their IDO-positive counterparts. The immunisation with this novel DC cancer vaccine was well tolerated and all patients developed delayed-type hypersensitivity skin reaction and specific T-cell response against hTERT and survivin tumour antigens. Perhaps most importantly, the immune response seen in the patients was related to objective clinical response. Thus, IDO silencing can enhance the immunogenic function of DCs in vitro and in vivo. Overall, the data provide proof-of-principle that immunisation with IDO-silenced DC vaccine is safe and effective in inducing antitumour immunity.

Clinical evaluation of therapeutic cancer vaccines

Therapeutic cancer vaccines are an immunotherapy that targets tumor antigens to induce an active immune response. To date, Provenge® is the only therapeutic cancer vaccine approved by the United States Food and Drug Administration. Although therapeutic cancer vaccines have not been approved by the European Medicines Agency (EMA), they have been approved in several countries other than the United States (US) and the European Union (EU). Provenge® is the only approved cancer vaccine that showed significant primary endpoint efficacy in a phase III study at the time of approval. Retrospective analysis of 23 completed or terminated phase III studies showed that 74% (17/23) failed to demonstrate significant efficacy in the primary endpoint. The reasons for failure were surveyed in 13 of the 17 studies. Despite efforts to minimize tumor burden, including surgery and induction chemotherapy before therapeutic cancer vaccine therapy, 69% (9/13) of the phase III studies failed. These findings indicate that tumor burden may not be the only prognostic factor. Immunological response has often been used as a predictive factor, and a small number of sub-group analyses have succeeded in showing that immunological response is associated with the efficacy of therapeutic cancer vaccines. Being a prognostic factor, inclusion of immunological response in addition to tumor stage in the eligibility criteria or sub-group analysis may minimize study population heterogeneity, a key factor in the success of phase III studies.

Analysis of pre-treatment markers predictive of treatment benefit for the therapeutic cancer vaccine MVA-5T4 (TroVax)

Cancer vaccines such as MVA-5T4 (TroVax(®)) must induce an efficacious immune response to deliver therapeutic benefit. The identification of biomarkers that impact on the clinical and/or immunological efficacy of cancer vaccines is required in order to select patients who are most likely to benefit from this treatment modality. Here, we sought to identify a predictor of treatment benefit for renal cancer patients treated with MVA-5T4. Statistical modeling was undertaken using data from a phase III trial in which patients requiring first-line treatment for metastatic renal cell carcinoma were randomized 1:1 to receive MVA-5T4 or placebo alongside sunitinib, IL-2 or IFN-α. Numerous pre-treatment factors associated with inflammatory anemia (e.g., CRP, hemoglobin, hematocrit, IL-6, ferritin, platelets) demonstrated a significant relationship with tumor burden and patient survival. From these prognostic factors, the pre-treatment mean corpuscular hemoglobin concentration (MCHC) was found to be the best predictor of treatment benefit (P < 0.01) for MVA-5T4 treated patients and also correlated positively with tumor shrinkage (P < 0.001). Furthermore, MCHC levels showed a significant positive association with 5T4 antibody response (P = 0.01). The latter result was confirmed using an independent data set comprising phase II trials of MVA-5T4 in patients with colorectal, renal and prostate cancers. Retrospective analyses demonstrated that RCC patients who had very large tumor burdens and low MCHC levels received little or no benefit from treatment with MVA-5T4; however, patients with smaller tumor burdens and normal MCHC levels received substantial benefit from treatment with MVA-5T4.

Serum-free freezing media support high cell quality and excellent ELISPOT assay performance across a wide variety of different assay protocols

Robust and sensitive ELISPOT protocols are commonly applied concomitant with the development of new immunotherapeutics. Despite the knowledge that individual serum batches differ in their composition and may change properties over time, serum is still commonly used in immunologic assays. Commercially available serum batches are expensive, limited in quantity and need to be pretested for suitability in immunologic assays, which is a laborious process. The aim of this study was to test whether serum-free freezing media can lead to high cell viability and favorable performance across multiple ELISPOT assay protocols. Thirty-one laboratories from ten countries participated in a proficiency panel organized by the Cancer Immunotherapy Immunoguiding Program to test the influence of different freezing media on cell quality and immunologic function. Each center received peripheral blood mononuclear cells which were frozen in three different media. The participants were asked to quantify antigen-specific CD8+ T-cell responses against model antigens using their locally established IFN-gamma ELISPOT protocols. Self-made and commercially available serum-free freezing media led to higher cell viability and similar cell recovery after thawing and resting compared to freezing media supplemented with human serum. Furthermore, the test performance as determined by (1) background spot production, (2) replicate variation, (3) frequency of detected antigen-specific spots and (4) response detection rate was similar for serum and serum-free conditions. We conclude that defined and accessible serum-free freezing media should be recommended for freezing cells stored for subsequent ELISPOT analysis.

Survivin-specific T-cell reactivity correlates with tumor response and patient survival: a phase-II peptide vaccination trial in metastatic melanoma

BACKGROUND

Therapeutic vaccination directed to induce an anti-tumoral T-cell response is a field of extensive investigation in the treatment of melanoma. However, many vaccination trials in melanoma failed to demonstrate a correlation between the vaccine-specific immune response and therapy outcome. This has been mainly attributed to immune escape by antigen loss, rendering us in the need of new vaccination targets.

PATIENTS AND METHODS

This phase-II trial investigated a peptide vaccination against survivin, an oncogenic inhibitor-of-apoptosis protein crucial for the survival of tumor cells, in HLA-A1/-A2/-B35-positive patients with treatment-refractory stage-IV metastatic melanoma. The study endpoints were survivin-specific T-cell reactivity (SSTR), safety, response, and survival (OS).

RESULTS

Sixty-one patients (ITT) received vaccination therapy using three different regimens. 55 patients (PP) were evaluable for response and survival, and 41/55 for SSTR. Patients achieving progression arrest (CR + PR + SD) more often showed SSTRs than patients with disease progression (p = 0.0008). Patients presenting SSTRs revealed a prolonged OS (median 19.6 vs. 8.6 months; p = 0.0077); multivariate analysis demonstrated SSTR as an independent predictor of survival (p = 0.013). The induction of SSTRs was associated with gender (female vs. male; p = 0.014) and disease stage (M1a/b vs. M1c; p = 0.010), but not with patient age, HLA type, performance status, or vaccination regimen.

CONCLUSION

Survivin-specific T-cell reactivities strongly correlate with tumor response and patient survival, indicating that vaccination with survivin-derived peptides is a promising treatment strategy in melanoma.

Estimating point and interval frequency of antigen-specific CD4+ T cells based on short in vitro expansion and improved poisson distribution analysis

BACKGROUND

Knowledge of antigen-specific CD4(+) T cells frequencies is pivotal to the choice of the antigen to be used in anti-viral and anti-tumor vaccination procedures and for monitoring of immune responses. Methods that employ small cell numbers from patient samples, are easy to perform and do not require complex techniques/instrumentations and therefore standardization are desirable.

METHODOLOGY/PRINCIPAL FINDINGS

Purified blood CD4(+) T cells from healthy donors were cultured with autologous antigen presenting cells in several replicate wells in equal numbers in the absence (un-stimulated wells) or in the presence of synthetic peptides corresponding to viral antigens promiscuous HLA-DR epitopes (antigen-stimulated wells). At day 7 of culture low dose IL-2 was added and at day 14 IFN-γ and IL-5 release in the supernatant was measured. A statistical analysis approach, based on Poisson distribution, was then implemented to calculate the frequency of viral-specific CD4(+) T cells. We first determined a patient-specific exceptionality threshold of cytokine release in the un-stimulated wells and then, based on this threshold, we counted the inactive/active wells within the antigen-stimulated wells. This number, along with the number of cells per well, allowed the point and interval estimates of frequencies. A ready-to-use Excel worksheet template with automatic calculations for frequencies estimate was developed and is provided as a supplemental file (Table S9).

CONCLUSIONS/SIGNIFICANCE

We report a simple experimental procedure combining short term in vitro cell culture with statistical analysis to calculate the frequency of antigen-specific CD4(+) T cells. The detailed experimental procedure along with the Excel applicative are a valuable tool for monitoring immune responses in the clinical practice.

Harmonization of immune biomarker assays for clinical studies

Assays that measure a patient's immune response play an increasingly important role in the development of immunotherapies. The inherent complexity of these assays and independent protocol development between laboratories result in high data variability and poor reproducibility. Quality control through harmonization--based on integration of laboratory-specific protocols with standard operating procedures and assay performance benchmarks--is one way to overcome these limitations. Harmonization guidelines can be widely implemented to address assay performance variables. This process enables objective interpretation and comparison of data across clinical trial sites and also facilitates the identification of relevant immune biomarkers, guiding the development of new therapies.

The immuno-oncology framework: Enabling a new era of cancer therapy

Developers of cancer immunotherapy have struggled for decades to achieve clinical success in using the patient's immune system to treat cancer. In the absence of a defined development paradigm for immunotherapies, conventional criteria established for chemotherapy were applied to these agents. This article summarizes the recent lessons for development of agents in the immunotherapy space, describes the systematic creation of a new clinical development paradigm for cancer immunotherapies and integrates this paradigm with the emerging methodological framework for a new clinical sub-specialty of immuno-oncology, which was driven by the collaborative work between the Cancer Immunotherapy Consortium (CIC) of the Cancer Research Institute in the US and the Association for Cancer Immunotherapy (CIMT) in Europe. This new framework provides a better defined development path and a foundation for more reproducible success of future therapies.

Defining the critical hurdles in cancer immunotherapy

Scientific discoveries that provide strong evidence of antitumor effects in preclinical models often encounter significant delays before being tested in patients with cancer. While some of these delays have a scientific basis, others do not. We need to do better. Innovative strategies need to move into early stage clinical trials as quickly as it is safe, and if successful, these therapies should efficiently obtain regulatory approval and widespread clinical application. In late 2009 and 2010 the Society for Immunotherapy of Cancer (SITC), convened an "Immunotherapy Summit" with representatives from immunotherapy organizations representing Europe, Japan, China and North America to discuss collaborations to improve development and delivery of cancer immunotherapy. One of the concepts raised by SITC and defined as critical by all parties was the need to identify hurdles that impede effective translation of cancer immunotherapy. With consensus on these hurdles, international working groups could be developed to make recommendations vetted by the participating organizations. These recommendations could then be considered by regulatory bodies, governmental and private funding agencies, pharmaceutical companies and academic institutions to facilitate changes necessary to accelerate clinical translation of novel immune-based cancer therapies. The critical hurdles identified by representatives of the collaborating organizations, now organized as the World Immunotherapy Council, are presented and discussed in this report. Some of the identified hurdles impede all investigators; others hinder investigators only in certain regions or institutions or are more relevant to specific types of immunotherapy or first-in-humans studies. Each of these hurdles can significantly delay clinical translation of promising advances in immunotherapy yet if overcome, have the potential to improve outcomes of patients with cancer.