Lessons from randomized phase III studies with active cancer immunotherapies--outcomes from the 2006 meeting of the Cancer Vaccine Consortium (CVC)

Simultaneous inference procedures for the comparison of multiple characteristics of two survival functions

Survival time is the primary endpoint of many randomized controlled trials, and a treatment effect is typically quantified by the hazard ratio under the assumption of proportional hazards. Awareness is increasing that in many settings this assumption is a priori violated, for example, due to delayed onset of drug effect. In these cases, interpretation of the hazard ratio estimate is ambiguous and statistical inference for alternative parameters to quantify a treatment effect is warranted. We consider differences or ratios of milestone survival probabilities or quantiles, differences in restricted mean survival times, and an average hazard ratio to be of interest. Typically, more than one such parameter needs to be reported to assess possible treatment benefits, and in confirmatory trials, the according inferential procedures need to be adjusted for multiplicity. A simple Bonferroni adjustment may be too conservative because the different parameters of interest typically show considerable correlation. Hence simultaneous inference procedures that take into account the correlation are warranted. By using the counting process representation of the mentioned parameters, we show that their estimates are asymptotically multivariate normal and we provide an estimate for their covariance matrix. We propose according to the parametric multiple testing procedures and simultaneous confidence intervals. Also, the logrank test may be included in the framework. Finite sample type I error rate and power are studied by simulation. The methods are illustrated with an example from oncology. A software implementation is provided in the R package nph.

Rechallenge of immunotherapy beyond progression in patients with extensive-stage small-cell lung cancer

Background: Rechallenge of immunotherapy beyond progression (RIBP) has been demonstrably effective in a variety of cancers. Our study aims to investigate the efficacy of RIBP in small-cell lung cancer (SCLC) patients under real-world conditions.

Methods: SCLC patients who experienced progressive disease after receiving programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1) inhibitors combined with chemotherapy from January 2017 to October 2021 were enrolled. The study population was divided into two groups: the RIBP group and the discontinuation of immunotherapy beyond progression (DIBP) group. Inverse propensity score weighting (IPSW) method was used to balance the clinical baseline characteristics. The short-term and long-term efficacy of the two groups was compared.

Results: 100 SCLC patients were included in this study. There were 45 patients in the RIBP group and 55 patients in the DIBP group. The disease control rate (DCR) and the proportion of durable clinical benefit (DCB) were significantly higher in the RIBP group (DCR: 79.7% vs. 55.7%, p = 0.027; DCB: 40.7 vs. 20.7%, p = 0.025) after weighting. The median progressive-free survival (PFS) in the RIBP group was significantly longer than the DIBP group in the total population (mPFS: 4.8 vs. 2.4 months, p = 0.002), while there was no significant difference in overall survival (OS) of the two groups (mOS: 17.4 vs. 8.0 months, p = 0.098). In the weighted first-line initial immunotherapy subgroup, PFS and OS were significantly improved in the RIBP group (mPFS: 4.5 vs. 2.8 months, p = 0.017; mOS: 11.6 vs. 5.4 months, p = 0.028). After weighting, the RIBP group had a significantly longer PFS than the DIBP group in the SD/PD response to the initial immunotherapy subgroup (mPFS: 6.8 vs. 1.8 months, p = 0.026).

Conclusion: Rechallenge of PD-1/PD-L1 inhibitors could bring benefits to SCLC patients, especially in the first-line initial immunotherapy subgroup or SD/PD response to the initial immunotherapy subgroup.

Cancer Vaccine in Cold Tumors: Clinical Landscape, Challenges, and Opportunities

The idea of cancer immunotherapy is to stimulate the immune system to fight tumors without destroying normal cells. One of the anticancer therapy methods, among many, is based on the use of cancer vaccines that contain tumor antigens in order to induce immune responses against tumors. However, clinical trials have shown that the use of such vaccines as a monotherapy is ineffective in many cases, since they do not cause a strong immune response. Particular tumors are resistant to immunotherapy due to the absence or insufficient infiltration of tumors with CD8+ T cells, and hence, they are called cold or non-inflamed tumors. Cold tumors are characterized by a lack of CD8+ T cell infiltration, the presence of anti-inflammatory myeloid cells, tumor-associated M2 macrophages, and regulatory T cells. It is very important to understand which stage of the antitumor response does not work properly in order to use the right strategy for the treatment of patients. Applying other therapeutic methods alongside cancer vaccines can be more rational for cold tumors which do not provoke the immune system strongly. Herein, we indicate some combinational therapies that have been used or are in progress for cold tumor treatment alongside vaccines.

Design for immuno-oncology clinical trials enrolling both responders and nonresponders

A typical challenge facing the design and analysis of immuno-oncology (IO) trials is the prevalence of nonproportional hazards (NPH) patterns manifested in Kaplan-Meier curves under time-to-event endpoints. The NPH patterns would violate the proportional hazards assumption, and yet conventional design and analysis strategies often ignore such a violation, resulting in underpowered or even falsely negative IO studies. In this article, we show, both empirically and analytically, that treating nonresponders in IO studies of inadequate size would give rise to a variety of NPH patterns; we then present a novel design and analysis strategy, P%-responder information embedded (PRIME), to properly incorporate the dichotomized response incurred from treating nonresponders. Empirical studies demonstrate that the proposed strategy can achieve desirable power, whereas the conventional alternative leads to a severe power loss. The PRIME strategy allows us to quantify the impact of treating nonresponders on study efficiency, thereby enabling a proper design of IO trials with an adequate power. More importantly, it pinpoints a solution to enhance the study efficiency and alleviates the NPH patterns by enrolling more prospective responders. An R package (Immunotherapy.Design) is developed for implementation.

Delayed treatment effects, treatment switching and heterogeneous patient populations: How to design and analyze RCTs in oncology

In the analysis of survival times, the logrank test and the Cox model have been established as key tools, which do not require specific distributional assumptions. Under the assumption of proportional hazards, they are efficient and their results can be interpreted unambiguously. However, delayed treatment effects, disease progression, treatment switchers or the presence of subgroups with differential treatment effects may challenge the assumption of proportional hazards. In practice, weighted logrank tests emphasizing either early, intermediate or late event times via an appropriate weighting function may be used to accommodate for an expected pattern of non‐proportionality. We model these sources of non‐proportional hazards via a mixture of survival functions with piecewise constant hazard. The model is then applied to study the power of unweighted and weighted log‐rank tests, as well as maximum tests allowing different time dependent weights. Simulation results suggest a robust performance of maximum tests across different scenarios, with little loss in power compared to the most powerful among the considered weighting schemes and huge power gain compared to unfavorable weights. The actual sources of non‐proportional hazards are not obvious from resulting populationwise survival functions, highlighting the importance of detailed simulations in the planning phase of a trial when assuming non‐proportional hazards.We provide the required tools in a software package, allowing to model data generating processes under complex non‐proportional hazard scenarios, to simulate data from these models and to perform the weighted logrank tests.

Safety and Efficacy of Therapeutic Cancer Vaccines Alone or in Combination With Immune Checkpoint Inhibitors in Cancer Treatment

Therapeutic cancer vaccines have proven to seldom induce dramatic clinical response when used alone, and therefore, they are being studied in combination with additional treatment modalities to achieve optimal treatment activities. Growing preclinical data show that combining vaccines and immune checkpoint inhibitors (ICIs) can prime intensified immunogenicity and modulate immunosuppressive tumor microenvironment. Herein, we focus on the safety and efficacy of approved and promising cancer vaccines alone or combined with ICIs in the treatment of several malignancies. Generally, the majority of clinical trials support the concept of synergy that combination therapy of vaccines and ICIs holds maximized potential to improve clinical outcomes. Importantly, the combination has acceptable safety and minimal additional toxicity compared with single-agent vaccines or ICIs. Additionally, the potential strategies of combining personalized tumor vaccines with ICIs will become priority option and future direction of vaccine development and application and the urgent need to develop effective biomarkers to screen appropriate patient populations and predict response to combination therapy.

Current Status of Immunotherapies for Treating Pancreatic Cancer

PURPOSE OF REVIEW

Despite all efforts, pancreatic ductal adenocarcinoma (PDAC) remains a disease that causes substantial morbidity and mortality, with a 5-year survival rate of 7%. Innovative paradigms for treating PDAC are urgently needed.

RECENT FINDINGS

We discuss the advances and difficulties in using immunotherapy and developing immunotherapeutic vaccines for PDAC. Current excitement about antigen-specific immunotherapy has been propelled by advances in multiple areas, such as next-generation sequencing to identify neoantigens and manufacturing to produce immunotherapeutic vaccines. Antigen-specific immunotherapy is being actively explored in clinical trials. As the field of immunotherapy matures and as our understanding of the complex interactions between tumor and host develops, we hope to identify new methods for treating and managing PDAC.

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.

Multiple Antigen Stimulating Cellular Therapy (MASCT) For Hepatocellular Carcinoma After Curative Treatment: A Retrospective Study

Background & Aims: The prognosis of hepatocellular carcinoma (HCC) remains poor and available treatment options are limited. This retrospective study evaluated the efficacy of Multiple Antigen Stimulating Cell Therapy (MASCT) as an adjuvant therapy for the treatment of HCC after curative treatment.

Methods: Patients who underwent HCC curative treatments were classified into two groups: the MASCT group, in which patients received MASCT treatment after curative treatment (n = 47), and the control group, in which patients did not receive any treatment after curative treatment (n = 99). Patients who received ≥ 5 courses of MASCT treatment before recurrence or death (n = 26) were further stratified into a subgroup (multiple-course MASCT group) for analysis. The primary endpoint was overall survival (OS). The secondary endpoints were disease-free survival (DFS) and safety.

Results: Kaplan-Meier analysis showed no statistically significant difference in OS between the MASCT group and the control group (P = 0.132), nor in DFS (P = 0.310) (median: 36.17 vs. 24.27 months). However, when comparing the multiple-course MASCT treated group to the control group, Kaplan-Meier analysis showed a significant difference in OS (P = 0.011), but not in DFS (P = 0.104) (median: 47.10 vs. 24.27 months). The overall incidences of treatment-related adverse events in the MASCT group and control group were 14.89% (7/47) and 19.19% (19/99), respectively. No MASCT treatment-related serious adverse events were reported.

Conclusions: Although the MASCT group was not associated with significantly longer OS or DFS, the multiple-course MASCT group showed significantly improved overall survival after curative treatment, and the treatment procedures were well-tolerated. Multiple-course MASCT may therefore provide another choice for patients with HCC after curative treatment.

Reporter gene imaging of targeted T cell immunotherapy in recurrent glioma

High-grade gliomas are aggressive cancers that often become rapidly fatal. Immunotherapy using CD8⁺ cytotoxic T lymphocytes (CTLs), engineered to express both herpes simplex virus type 1 thymidine kinase (HSV1-TK) and interleukin-13 (IL-13) zetakine chimeric antigen receptor (CAR), is a treatment strategy with considerable potential. To optimize this and related immunotherapies, it would be helpful to monitor CTL viability and trafficking to glioma cells. We show that noninvasive positron emission tomography (PET) imaging with 9-[4-[¹⁸F]fluoro-3-(hydroxymethyl)butyl]guanine ([¹⁸F]FHBG) can track HSV1-tk reporter gene expression present in CAR-engineered CTLs. [¹⁸F]FHBG imaging was safe and enabled the longitudinal imaging of T cells stably transfected with a PET reporter gene in patients. Further optimization of this imaging approach for monitoring in vivo cell trafficking should greatly benefit various cell-based therapies for cancer.

Informatics for cancer immunotherapy

The rapid development of immunomodulatory cancer therapies has led to a concurrent increase in the application of informatics techniques to the analysis of tumors, the tumor microenvironment, and measures of systemic immunity. In this review, the use of tumors to gather genetic and expression data will first be explored. Next, techniques to assess tumor immunity are reviewed, including HLA status, predicted neoantigens, immune microenvironment deconvolution, and T-cell receptor sequencing. Attempts to integrate these data are in early stages of development and are discussed in this review. Finally, we review the application of these informatics strategies to therapy development, with a focus on vaccines, adoptive cell transfer, and checkpoint blockade therapies.

Cancer vaccines: Enhanced immunogenic modulation through therapeutic combinations

Therapeutic cancer vaccines have gained significant popularity in recent years as new approaches for specific oncologic indications emerge. Three therapeutic cancer vaccines are FDA approved and one is currently approved by the EMA as monotherapy with modest treatment effects. Combining therapeutic cancer vaccines with other treatment modalities like radiotherapy (RT), hormone therapy, immunotherapy, and/or chemotherapy have been investigated as a means to enhance immune response and treatment efficacy. There is growing preclinical and clinical data that combination of checkpoint inhibitors and vaccines can induce immunogenic intensification with favorable outcomes. Additionally, novel methods for identifying targetable neoantigens hold promise for personalized vaccine development. In this article, we review the rationale for various therapeutic combinations, clinical trial experiences, and future directions. We also highlight the most promising developments that could lead to approval of novel therapeutic cancer vaccines.

Cancer Immunotherapy: Historical Perspective of a Clinical Revolution and Emerging Preclinical Animal Models

At the turn of the last century, the emerging field of medical oncology chose a cytotoxic approach to cancer therapy over an immune-centered approach at a time when evidence in support of either paradigm did not yet exist. Today, nearly 120 years of data have established that (a) even the best cytotoxic regimens only infrequently cure late-stage malignancy and (b) strategies that supplement and augment existing antitumor immune responses offer the greatest opportunities to potentiate durable remission in cancer. Despite widespread acceptance of these paradigms today, the ability of the immune system to recognize and fight cancer was a highly controversial topic for much of the twentieth century. Why this modern paradigmatic mainstay should have been both dubious and controversial for such an extended period is a topic of considerable interest that merits candid discussion. Herein, we review the literature to identify and describe the watershed events that ultimately led to the acceptance of immunotherapy as a viable regimen for the treatment of neoplastic malignancy. In addition to noting important clinical discoveries, we also focus on research milestones and the development of critical model systems in rodents and dogs including the advanced modeling techniques that allowed development of patient-derived xenografts. Together, their use will further our understanding of cancer biology and tumor immunology, allow for a speedier assessment of the efficacy and safety of novel approaches, and ultimately provide a faster bench to beside transition.

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.

Safety and Efficacy of Nivolumab in Patients With Metastatic Renal Cell Carcinoma Treated Beyond Progression: A Subgroup Analysis of a Randomized Clinical Trial

IMPORTANCE

Response patterns with immunotherapy may differ from those of other treatments. This warrants further investigation because some patients may benefit from continued immunotherapy beyond Response Evaluation Criteria in Solid Tumors (RECIST)-defined first progression.

OBJECTIVE

To evaluate the safety and potential benefit of treatment with nivolumab, a programmed cell death 1 immune checkpoint inhibitor, beyond investigator-assessed first progression in patients with metastatic renal cell carcinoma (mRCC).

DESIGN, SETTING, AND PARTICIPANTS

Subgroup analysis of a blinded, randomized, multicenter, phase 2 dose-ranging trial initiated May 31, 2011, including patients with clear-cell mRCC previously treated with antiangiogenic therapy. Data cutoffs for this subgroup analysis were May 15, 2013, for progression-free survival and objective response rate and March 5, 2014, for overall survival and duration of response. In this analysis, patients treated beyond first progression received their last dose of nivolumab more than 6 weeks after RECIST-defined progression, and patients not treated beyond first progression discontinued nivolumab before or at RECIST-defined progression.

INTERVENTIONS

Nivolumab 0.3, 2, or 10 mg/kg intravenously every 3 weeks.

MAIN OUTCOMES AND MEASURES

Safety and efficacy of nivolumab treatment.

RESULTS

Of 168 patients (median [range] age, 61 [37-81] years; 72% male) randomized to nivolumab, 154 experienced progression (36 were treated beyond first progression, 26 were treated beyond first progression for ≤6 weeks, and 92 were not treated beyond first progression), 13 were treated and did not experience progression, and 1 was not treated. Prior to first progression, the RECIST-defined objective response rate was 14% (5 patients) and 16% (15 patients), and median progression-free survival was 4.2 (95% CI, 2.8-5.5) and 2.6 (95% CI, 1.5-3.9) months in patients treated and not treated beyond progression, respectively. Following initial progression, 25 (69%) patients treated beyond progression experienced subsequent tumor reduction or stabilization in target lesion size. The incidence of treatment-related adverse events was higher in patients treated beyond progression (n = 29 [81%]) vs those not treated beyond progression (n = 61 [66%]); however, after adjusting for length of treatment exposure, incidence was lower in patients treated beyond progression (322.9 vs 518.7 incidence rate/100 patient-years for patients treated vs not treated beyond progression).

CONCLUSIONS AND RELEVANCE

In this subgroup analysis, a proportion of patients who continued treatment beyond RECIST-defined first progression demonstrated sustained reductions in tumor burden or stabilization in the size of target lesions, with an acceptable safety profile. Further analysis will help define the clinical benefit for patients with mRCC treated with nivolumab beyond progression.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01354431.

De-Risking Immunotherapy: Report of a Consensus Workshop of the Cancer Immunotherapy Consortium of the Cancer Research Institute

With the recent FDA approvals of pembrolizumab and nivolumab, and a host of additional immunomodulatory agents entering clinical development each year, the field of cancer immunotherapy is changing rapidly. Strategies that can assist researchers in choosing the most promising drugs and drug combinations to move forward through clinical development are badly needed in order to reduce the likelihood of late-stage clinical trial failures. On October 5, 2014, the Cancer Immunotherapy Consortium of the Cancer Research Institute, a collaborative think tank composed of stakeholders from academia, industry, regulatory agencies, and patient interest groups, met to discuss strategies for de-risking immunotherapy development, with a focus on integrating preclinical and clinical studies, and conducting smarter early-phase trials, particularly for combination therapies. Several recommendations were made, including making better use of clinical data to inform preclinical research, obtaining adequate tissues for biomarker studies, and choosing appropriate clinical trial endpoints to identify promising drug candidates and combinations in nonrandomized early-phase trials.

Do Helper T Cell Subtypes in Lymphocytic Thyroiditis Play a Role in the Antitumor Effect?

BACKGROUND

Papillary thyroid carcinoma (PTC) is frequently accompanied by lymphocytic thyroiditis (LT). Some reports claim that Hashimoto's thyroiditis (the clinical form of LT) enhances the likelihood of PTC; however, others suggest that LT has antitumor activity. This study was aimed to find out the relationship between the patterns of helper T cell (Th) cytokines in thyroid tissue of PTC with or without LT and the clinicopathological manifestation of PTC.

METHODS

Fresh surgical samples of PTC with (13 cases) or without (10 cases) LT were used. The prognostic parameters (tumor size, extra-thyroidal extension of PTC, and lymph node metastasis) were analyzed. The mRNA levels of two subtypes of Th cytokines, Th1 (tumor necrosis factor α [TNF-α], interferon γ [IFN-γ ], and interleukin [IL] 2) and Th2 (IL-4 and IL-10), were analyzed. Because most PTC cases were microcarcinomas and recent cases without clinical follow-up, negative or faint p27 immunoreactivity was used as a surrogate marker for lymph node metastasis.

RESULTS

PTC with LT cases showed significantly higher expression of TNF-α (p = .043), IFN-γ (p < .010), IL-4 (p = .015) than those without LT cases. Although the data were not statistically significant, all analyzed cytokines (except for IL-4) were highly expressed in the cases with higher expression of p27 surrogate marker.

CONCLUSIONS

These results indicate that mixed Th1 (TNF-α, IFN-γ , and IL-2) and Th2 (IL-10) immunity might play a role in the antitumor effect in terms of lymph node metastasis.

Unraveling the immunopathogenesis of glomerular disease

Immune-mediated damage to glomerular structures is largely responsible for the pathology associated with the majority of glomerular diseases. Therefore, a detailed understanding of the basic immune mechanisms responsible for glomerular damage is needed to inform the design of novel intervention strategies. Glomerular injury of immune origin is complex and involves both inflammatory and non-inflammatory processes driven by elements of the innate and adaptive immune system. This review summarizes the basic immune mechanisms that cause glomerular injury leading to the nephritic and nephrotic syndromes. A major focus of the review is to highlight the mechanisms by which antibodies cause glomerular injury through their interactions with glomerular cells, complement proteins, phagocytes bearing complement and Fcγ receptors, and dendritic cells expressing the neonatal receptor for IgG, FcRn.

Immuno-oncology combinations: raising the tail of the survival curve

There have been exponential gains in immuno-oncology in recent times through the development of immune checkpoint inhibitors. Already approved by the U.S. Food and Drug Administration for advanced melanoma and non-small cell lung cancer, immune checkpoint inhibitors also appear to have significant antitumor activity in multiple other tumor types. An exciting component of immunotherapy is the durability of antitumor responses observed, with some patients achieving disease control for many years. Nevertheless, not all patients benefit, and efforts should thus now focus on improving the efficacy of immunotherapy through the use of combination approaches and predictive biomarkers of response and resistance. There are multiple potential rational combinations using an immunotherapy backbone, including existing treatments such as radiotherapy, chemotherapy or molecularly targeted agents, as well as other immunotherapeutics. The aim of such antitumor strategies will be to raise the tail on the survival curve by increasing the number of long term survivors, while managing any additive or synergistic toxicities that may arise with immunotherapy combinations. Rational trial designs based on a clear understanding of tumor biology and drug pharmacology remain paramount. This article reviews the biology underpinning immuno-oncology, discusses existing and novel immunotherapeutic combinations currently in development, the challenges of predictive biomarkers of response and resistance and the impact of immuno-oncology on early phase clinical trial design.

Phase I clinical trial of a five-peptide cancer vaccine combined with cyclophosphamide in advanced solid tumors

We designed a phase I trial to investigate the safety, immune responses and clinical benefits of a five-peptide cancer vaccine in combination with chemotherapy. Study subjects were patients positive for HLA-A2402 with locally advanced, metastatic, and/or recurrent gastrointestinal, lung or cervical cancer. Eighteen patients including nine cases of colorectal cancer were treated with escalating doses of cyclophosphamide 4days before vaccination. Five HLA-A2402-restricted, tumor-associated antigen (TAA) epitope peptides from KOC1, TTK, URLC10, DEPDC1 and MPHOSPH1 were injected weekly for 4weeks. Treatment was well tolerated without any adverse events above grade 3. Analysis of peripheral blood lymphocytes showed that the number of regulatory T cells dropped from baseline after administration of cyclophosphamide and confirmed that TAA-specific T cell responses were associated significantly with longer overall survival. This phase I clinical trial demonstrated safety and promising immune responses that correlated with vaccine-induced T-cell responses. Therefore, this approach warrants further clinical studies.

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.

Prospective immunotherapies in childhood sarcomas: PD1/PDL1 blockade in combination with tumor vaccines

Progress has slowed substantially in improving survival rates for pediatric sarcomas, particularly in refractory and metastatic disease. Significant progress has been made in the field of tumor vaccines for such malignancies, which target established tumor antigens. While tumor vaccines have demonstrated safety and improved survival rates, they are inadequate in mediating the regression of established tumor masses and metastases. Programmed cell death ligand 1 (PDL1) is a cell-surface protein induced in a number of adult malignancies. By acting on the corresponding T-cell receptor PD1, PDL1 is able to suppress cytotoxic T-cell-mediated tumor responses. Recent therapeutics blocking this interaction have shown promise in various adult cancers by restoring a functional T-cell response and by directing this response toward an activated, rather than regulatory, T-cell phenotype. We shall discuss the current state of tumor vaccines targeting pediatric sarcomas, review PD1-PDL1 interactions and current therapies targeting these interactions in adult malignancies, and discuss recent studies in which tumor vaccines, combined with PDL1 blockades, produced superior tumor regression compared with the vaccine alone. These studies provide a compelling case for investigation of PDL1 expression and its inhibition in pediatric sarcomas, while continuing to utilize tumor vaccines in tandem to achieve superior clinical outcomes.

Opposing effects of immunotherapy in melanoma using multisubtype interferon-alpha - can tumor immune escape after immunotherapy accelerate disease progression?

With checkpoint inhibitors, patients with advanced melanoma display durable responses suggesting cure of disease. However, the immune system has dual roles in cancer; while the immune system may eradicate a tumor, a subtotal elimination may selectively destroy immunogenic cells driving the proliferation of non-immunogenic tumors. Here, we performed a retrospective analysis of results obtained in a controlled trial of patients with melanoma treated with adjuvant, multisubtype interferon-α. The survival curves displayed a late divergence for treated patients and controls resulting in substantially higher estimates of overall (OS) and relapse-free survival (RFS) rates among treated patients after 9 y of follow up. Interestingly, succumbing patients in the treatment group displayed reduced time between relapse and death, suggesting therapy-induced acceleration of disease progression. These findings suggest that effective immunotherapy that induces durable, curative responses in some patients, may potentially accelerate disease progression in others, highlighting the importance of developing advanced strategies to identify patients who are likely to benefit from immunotherapy.

Survivin-targeted immunotherapy drives robust polyfunctional T cell generation and differentiation in advanced ovarian cancer patients

DepoVax™ is an innovative and strongly immunogenic vaccine platform. Survivin is highly expressed in many tumor types and has reported prognostic value. To generate tumor-specific immune response, a novel cancer vaccine was formulated in DepoVax platform (DPX-Survivac) using survivin HLA class I peptides. Safety and immune potency of DPX-Survivac was tested in combination with immune-modulator metronomic cyclophosphamide in ovarian cancer patients. All the patients receiving the therapy produced antigen-specific immune responses; higher dose vaccine and cyclophosphamide treatment generating significantly higher magnitude responses. Strong T cell responses were associated with differentiation of naïve T cells into central/effector memory (CM/EM) and late differentiated (LD) polyfunctional antigen-specific CD4⁺ and CD8⁺ T cells. This approach enabled rapid de novo activation/expansion of vaccine antigen-specific CD8⁺ T cells and provided a strong rationale for further testing to determine clinical benefits associated with this immune activation. These data represent vaccine-induced T cell activation in a clinical setting to a self-tumor antigen previously described only in animal models.

Long-term survival in advanced melanoma patients using repeated therapies: successive immunomodulation improving the odds?

Background

Patients with advanced metastatic melanoma are often confronted with little prospect of medium- to longer-term survival by any currently available therapeutic means. However, most clinicians are aware of exceptional cases where survival defies the notion of futility. Prolonged survival from immunotherapies, including interleukin-2, vaccines and antibodies to cytotoxic lymphocyte antigen-4, and programmed death-1 receptor inhibitory monoclonal antibody, implies a role for immune system modulation. We aimed to identify cases where exceptional survival from advanced melanoma occurred prior to recent novel therapies to facilitate better understanding of this phenomenon.

Methods

Cases of long-term survival of ≥3 years’ duration (from diagnosis of metastatic disease) were identified from the database of one clinician; these cases were treated before the availability of newer immunotherapies, and they were documented and examined. A literature search for reported outcome measures from published studies using older and recent therapies for advanced melanoma was conducted to enable the comparison of data.

Results

Eighteen cases were identified that identified survival of ≥3 years’ duration from metastatic disease (12 American Joint Committee on Cancer [AJCC] Stage IV cases; six AJCC III cases) diagnosis. These were assessed and reported to detail the clinical course. Standard clinical prognostication methods predicted high risk of early mortality in those patients. No identifiable differences could be detected between these and other patients with similar patterns of disease. At evaluation, 17 patients (94%) had survived ≥5 years, and eleven patients (61%) had survived ≥10 years (range: 3–15 years). The median survival duration with metastatic disease was 11 years; 15 remained alive and three had died. Published studies of melanoma therapies were tabled for comparison.

Conclusion

The fact that 18 cases of exceptional survival in advanced melanoma were identified is remarkable in itself. Even with recent therapies, the factors for improved survival remain enigmatic; however, one apparent common denominator in most cases was the persistent use of repeated therapies to reduce tumor bulk, induce tumor necrosis, and/or cause immunostimulation. These cases are instructive, suggesting manipulation of an established, endogenous, existing immune response. These observations provide practical evidence that the course for any patient with advanced melanoma at the outset should be considered unpredictable, open to immunomanipulation, and thus not uniformly fatal. The findings were compared and interpreted with reported newer immunotherapeutic approaches.

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.

Awareness and understanding of cancer immunotherapy in Europe

The use of immunotherapy in the management of cancer is growing, and a range of new immunotherapeutic strategies is becoming available. It is important that people involved in the care of cancer understand how cancer immunotherapies differ from conventional chemotherapy and apply this knowledge to their clinical practice. Therefore, from August-September 2011 we undertook a survey of awareness, attitudes, and perceptions of cancer immunotherapy among 426 healthcare professionals (HCPs) in Europe with the aim of identifying and prioritizing educational needs. Nearly all (98%) HCPs were aware of cancer immunotherapy. While 68% of HCPs indicated a high level of interest in cancer immunotherapies, only 24% of the HCPs had direct experience with them. Overall perceptions of cancer immunotherapy among HCPs were largely positive (60%) and rarely negative (3%). The key advantages of cancer immunotherapy were perceived to be good safety and tolerability (75%), a targeted mechanism of action (61%) and good efficacy (48%). The leading barriers to use of immunotherapies were costs of treatment (58%), past clinical trial failures (45%), and access/formulary restrictions (44%). The results indicate that, among the respondents, awareness of cancer immunotherapy was high but that knowledge levels varied and direct experience with their use was limited. There appears to be a need for educational activities on cancer immunotherapy, as well as generation and communication of clinical data on long-term efficacy and safety.

Clinical Implications of Co-Inhibitory Molecule Expression in the Tumor Microenvironment for DC Vaccination: A Game of Stop and Go

The aim of therapeutic dendritic cell (DC) vaccines in cancer immunotherapy is to activate cytotoxic T cells to recognize and attack the tumor. T cell activation requires the interaction of the T cell receptor with a cognate major-histocompatibility complex-peptide complex. Although initiated by antigen engagement, it is the complex balance between co-stimulatory and co-inhibitory signals on DCs that results in T cell activation or tolerance. Even when already activated, tumor-specific T cells can be neutralized by the expression of co-inhibitory molecules on tumor cells. These and other immunosuppressive cues in the tumor microenvironment are major factors currently hampering the application of DC vaccination. In this review, we discuss recent data regarding the essential and complex role of co-inhibitory molecules in regulating the immune response within the tumor microenvironment. In particular, possible therapeutic intervention strategies aimed at reversing or neutralizing suppressive networks within the tumor microenvironment will be emphasized. Importantly, blocking co-inhibitory molecule signaling, often referred to as immune checkpoint blockade, does not necessarily lead to an effective activation of tumor-specific T cells. Therefore, combination of checkpoint blockade with other immune potentiating therapeutic strategies, such as DC vaccination, might serve as a synergistic combination, capable of reversing effector T cells immunosuppression while at the same time increasing the efficacy of T cell-mediated immunotherapies. This will ultimately result in long-term anti-tumor immunity.

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.

Immunological monitoring of anticancer vaccines in clinical trials

Therapeutic anticancer vaccines operate by eliciting or enhancing an immune response that specifically targets tumor-associated antigens. Although intense efforts have been made for developing clinically useful anticancer vaccines, only a few Phase III clinical trials testing this immunotherapeutic strategy have achieved their primary endpoint. Here, we report the results of a retrospective research aimed at clarifying the design of previously completed Phase II/III clinical trials testing therapeutic anticancer vaccines and at assessing the value of immunological monitoring in this setting. We identified 17 anticancer vaccines that have been investigated in the context of a completed Phase II/III clinical trial. The immune response of patients receiving anticancer vaccination was assessed for only 8 of these products (in 15 distinct studies) in the attempt to identify a correlation with clinical outcome. Of these studies, 13 were supported by a statistical correlation study (Log-rank test), and no less than 12 identified a positive correlation between vaccine-elicited immune responses and disease outcome. Six trials also performed a Cox proportional hazards analysis, invariably demonstrating that vaccine-elicited immune responses have a positive prognostic value. However, despite these positive results in the course of early clinical development, most therapeutic vaccines tested so far failed to provide any clinical benefit to cancer patients in Phase II/III studies. Our research indicates that evaluating the immunological profile of patients at enrollment might constitute a key approach often neglected in these studies. Such an immunological monitoring should be based not only on peripheral blood samples but also on bioptic specimens, whenever possible. The evaluation of the immunological profile of cancer patients enrolled in early clinical trials will allow for the identification of individuals who have the highest chances to benefit from anticancer vaccination, thus favoring the rational design of Phase II and Phase III studies. This approach will undoubtedly accelerate the clinical development of therapeutic anticancer vaccines.

Biological delivery approaches for gene therapy: strategies to potentiate efficacy and enhance specificity

Nowadays many therapeutic agents such as suicide genes, anti-angiogenesis agents, cytokines, chemokines and other therapeutic genes were delivered to cancer cells. Various biological delivery systems have been applied for directing therapeutic gene to target cells. Some of these successful preclinical studies, steps forward to clinical trials and a few are examined in phase III clinical trials. In this review, the biological gene delivery systems were categorized into microorganism and cell based delivery systems. Viral, bacterial, yeast and parasite are among microorganism based delivery systems which are expanded in this review. In cell based approach, different strategies such as tumor cells, stem cells, dendritic cells and sertoli cells will be discussed. Different drawbacks are associated with each delivery system; therefore, many strategies have been improved and potentiated their direction toward specific target cells. Herein, further to the principle of each delivery system, the progresses of these approaches for development of newer generation are discussed.

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.

Selected anti-tumor vaccines merit a place in multimodal tumor therapies

Multimodal approaches are nowadays successfully applied in cancer therapy. Primary locally acting therapies such as radiotherapy (RT) and surgery are combined with systemic administration of chemotherapeutics. Nevertheless, the therapy of cancer is still a big challenge in medicine. The treatments often fail to induce long-lasting anti-tumor responses. Tumor recurrences and metastases result. Immunotherapies are therefore ideal adjuncts to standard tumor therapies since they aim to activate the patient's immune system against malignant cells even outside the primary treatment areas (abscopal effects). Especially cancer vaccines may have the potential both to train the immune system against cancer cells and to generate an immunological memory, resulting in long-lasting anti-tumor effects. However, despite promising results in phase I and II studies, most of the concepts finally failed. There are some critical aspects in development and application of cancer vaccines that may decide on their efficiency. The time point and frequency of medication, usage of an adequate immune adjuvant, the vaccine's immunogenic potential, and the tumor burden of the patient are crucial. Whole tumor cell vaccines have advantages compared to peptide-based ones since a variety of tumor antigens (TAs) are present. The master requirements of cell-based, therapeutic tumor vaccines are the complete inactivation of the tumor cells and the increase of their immunogenicity. Since the latter is highly connected with the cell death modality, the inactivation procedure of the tumor cell material may significantly influence the vaccine's efficiency. We therefore also introduce high hydrostatic pressure (HHP) as an innovative inactivation technology for tumor cell-based vaccines and outline that HHP efficiently inactivates tumor cells by enhancing their immunogenicity. Finally studies are presented proving that anti-tumor immune responses can be triggered by combining RT with selected immune therapies.

Dendritic cell-based vaccination in metastatic melanoma patients: phase II clinical trial

Metastatic and chemoresistant melanoma can be a good target of immunotherapy because it is an intractable cancer with a very poor prognosis. Previously, we tested a dendritic cell (DC)-based phase I vaccine, and confirmed that it was safe. In the present study, we performed a phase II trial of a DC vaccine for metastatic melanoma patients with mainly the HLA-A24 genotype, and investigated the efficacy of the vaccine. Twenty-four patients with metastatic melanoma were enrolled into a phase II study of DC-based immunotherapy. The group included 19 HLA-A24-positive (A*2402) patients and 3 HLA-A2-positive (A*0201) patients. The protocol for DC production was similar to that in the phase I trial. Briefly, a cocktail of 5 melanoma-associated synthetic peptides (gp100, tyrosinase, MAGE-A2, MAGE-A3 and MART-1 or MAGE‑A1) restricted to HLA-A2 or A24 and KLH were used for DC pulsing. Finally, DCs were injected subcutaneously (s.c.) into the inguinal region in the dose range of 1-5x107 per shot. The DC ratio (lin-HLA-DR+) of the vaccine was 38.1±13.3% and the frequency of CD83+ DCs was 25.7±20.8%. Other parameters regarding DC processing were not different from phase I. Immune response-related parameters including the ELISPOT assay, DTH reaction to peptide or KLH, DC injection numbers were shown to be related to a good prognosis. The ELISPOT reaction was positive in 75% of the patients vaccinated. The increase of anti-melanoma antigen antibody titer before vaccination was also shown to be a prognosis factor, but that post-vaccination was not. Based on immunohistochemical analysis, CD8 and IL-17 were not involved in the prognosis. Adverse effects of more than grade III were not seen. Overall survival analysis revealed a significant survival prolongation effect in DC-given melanoma patients. These results suggest that peptide cocktail-treated DC vaccines may be a safe and effective therapy against metastatic melanoma in terms of prolongation of overall survival time.

Cancer vaccines: are we there yet?

For nearly two decades there has been an abundance of research and clinical development programs underway to develop active specific immunotherapies, to educate the patient’s immune response, specifically the T-cell immunity and memory, to recognize and destroy tumor cells by cell-mediated cellular toxicity. While many of these technology platforms achieved promising results in preclinical and clinical phase I and II clinical trials, essentially all but one have failed to achieve FDA market approval as a therapeutic drug product.

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.

Update on prostate cancer vaccines

The recent approval of Sipuleucel-T (Dendreon, Seattle, WA) from the Food and Drug Administration for the treatment of men with asymptomatic or minimally symptomatic castrate-resistant prostate cancer was a landmark in cancer immunotherapy, making this the first cancer "vaccine" approved for use in a treatment setting. This approval has led to renewed interest in cancer vaccines and to the recognition that prostate cancer represents an immunologically sensitive disease. At the current time, several vaccine approaches are under clinical investigation. These include viral vectors, antigen-loaded dendritic cells, and DNA vaccines. Each approach has its own set of advantages and disadvantages. This review will introduce the basic technology underlying these different vaccines and briefly discuss completed and ongoing clinical trials. As a great number of prostate cancer vaccines have been investigated in both preclinical and clinical settings, we will focus primarily on vaccines that are currently in clinical trials, as ascertained by a recent inquiry of the clinical trials database, www.clinicaltrials.gov.

Endpoints, patient selection, and biomarkers in the design of clinical trials for cancer vaccines

Therapeutic cancer vaccines are an emerging and potentially effective treatment modality. Cancer vaccines are usually very well tolerated, with minimal toxicity compared with chemotherapy. Unlike conventional cytotoxic therapies, immunotherapy does not result in immediate tumor shrinkage but may alter growth rate and thus prolong survival. Multiple randomized controlled trials of various immunotherapeutic agents have shown a delayed separation in Kaplan-Meier survival curves, with no evidence of clinical benefit within the first 6-12 months of vaccine treatment. Overall survival benefit is seen in patients with lower disease burden who are not expected to die within those initial 6-12 months. The concept of improved overall survival without marked initial tumor reduction represents a significant shift from the current paradigms established by standard cytotoxic therapies. Future clinical studies of therapeutic vaccines should enroll patients with either lower tumor burden, more indolent disease or both, and must seek to identify early markers of clinical benefit that may correlate with survival. Until then, improved overall survival is the only clear, discriminatory endpoint for therapeutic vaccines as monotherapies.

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.

Murine rhabdomyosarcoma is immunogenic and responsive to T-cell-based immunotherapy

BACKGROUND

Immunotherapies targeting cellular immunity are currently approved for treatment of melanoma, renal cell carcinoma, and prostate cancer. Studies on the immunogenicity and immune responsiveness of pediatric tumors are limited, therefore, it remains unclear to what extent T-cell-based immunotherapy holds promise for pediatric solid tumors.

PROCEDURE

A new rhabdomyosarcoma cell line (M3-9-M) was derived from an embryonal rhabdomyosarcoma (ERMS) occurring in a C57BL/6 mouse transgenic for hepatocyte growth factor and heterozygous for mutated p53. Primary tumors and metastases derived from M3-9-M were studied for similarities to human ERMS, and for immunogenicity and immune responsiveness.

RESULTS

Primary and metastatic tumors develop after orthotopic injection of M3-9-M into immunocompetent C57BL/6 mice, which mirror human ERMS with regard to histology, gene expression, and metastatic behavior. Whole cell vaccination using irradiated M3-9-M cells or M3-9-M-pulsed dendritic cells (DC)-induced tumor-specific T-cell responses that prevent tumor growth following low-dose tumor injection, and slow tumor growth following higher doses. Administration of anti-CD25 moAbs to deplete CD4(+)CD25(+)FOXP3(+) regulatory T cells prior to tumor vaccination enhanced the potency of the ERMS tumor vaccine. Adoptive immunotherapy with M3-9-M primed T cells plus DC-based vaccination resulted in complete eradication of day 10 M3-9-M derived tumors.

CONCLUSIONS

M3-9-M derived murine ERMS is immunogenic and immunoresponsive; regulatory T cells contribute to immune evasion by murine rhabdomyosarcoma. Adoptive immunotherapy with DC vaccination can eradicate low tumor burdens. Future work will seek to identify the tumor-associated antigens that mediate protective and therapeutic immunity in this model.

A pilot study of MUC-1/CEA/TRICOM poxviral-based vaccine in patients with metastatic breast and ovarian cancer

PURPOSE

PANVAC is a recombinant poxviral vaccine that contains transgenes for MUC-1, CEA, and 3 T-cell costimulatory molecules. This study was conducted to obtain preliminary evidence of clinical response in metastatic breast and ovarian cancer patients.

EXPERIMENTAL DESIGN

Twenty-six patients were enrolled and given monthly vaccinations. Clinical and immune outcomes were evaluated.

RESULTS

These patients were heavily pretreated, with 21 of 26 patients having 3 or more prior chemotherapy regimens. Side effects were largely limited to mild injection-site reactions. For the 12 breast cancer patients enrolled, median time to progression was 2.5 months (1-37+) and median overall survival was 13.7 months. Four patients had stable disease. One patient had a complete response by RECIST and remained on study for 37 months or more, with a significant drop in serum interleukin (IL)-6 and IL-8 by day 71. Another patient with metastatic disease confined to the mediastinum had a 17% reduction in mediastinal mass and was on study for 10 months. Patients with stable or responding disease had fewer prior therapies and lower tumor marker levels than patients with no evidence of response. For the ovarian cancer patients (n = 14), the median time to progression was 2 months (1-6) and median overall survival was 15.0 months. Updated data are presented here for one patient treated with this vaccine in a previous trial, with a time to progression of 38 months.

CONCLUSIONS

Some patients who had limited tumor burden with minimal prior chemotherapy seemed to benefit from the vaccine. Further studies to confirm these results are warranted.

Biomarkers in T cell therapy clinical trials

T cell therapy represents an emerging and promising modality for the treatment of both infectious disease and cancer. Data from recent clinical trials have highlighted the potential for this therapeutic modality to effect potent anti-tumor activity. Biomarkers, operationally defined as biological parameters measured from patients that provide information about treatment impact, play a central role in the development of novel therapeutic agents. In the absence of information about primary clinical endpoints, biomarkers can provide critical insights that allow investigators to guide the clinical development of the candidate product. In the context of cell therapy trials, the definition of biomarkers can be extended to include a description of parameters of the cell product that are important for product bioactivity.

This review will focus on biomarker studies as they relate to T cell therapy trials, and more specifically: i. An overview and description of categories and classes of biomarkers that are specifically relevant to T cell therapy trials, and ii. Insights into future directions and challenges for the appropriate development of biomarkers to evaluate both product bioactivity and treatment efficacy of T cell therapy trials.