White paper on adoptive cell therapy for cancer with tumor-infiltrating lymphocytes: a report of the CTEP subcommittee on adoptive cell therapy

Autologous human preclinical modeling of melanoma interpatient clinical responses to immunotherapeutics

BACKGROUND

Despite recent advances in immunotherapy, a substantial population of late-stage melanoma patients still fail to achieve sustained clinical benefit. Lack of translational preclinical models continues to be a major challenge in the field of immunotherapy; thus, more optimized translational models could strongly influence clinical trial development. To address this unmet need, we designed a preclinical model reflecting the heterogeneity in melanoma patients' clinical responses that can be used to evaluate novel immunotherapies and synergistic combinatorial treatment strategies. Using our all-autologous humanized melanoma mouse model, we examined the efficacy of a novel engineered interleukin 2 (IL-2)-based cytokine variant immunotherapy.

METHODS

To study immune responses and antitumor efficacy for human melanoma tumors, we developed an all-autologous humanized melanoma mouse model using clinically annotated, matched patient tumor cells and peripheral blood mononuclear cells (PBMCs). After inoculating immunodeficient NSG mice with patient tumors and an adoptive cell transfer of autologous PBMCs, mice were treated with anti-PD-1, a novel investigational engineered IL-2-based cytokine (nemvaleukin), or recombinant human IL-2 (rhIL-2). The pharmacodynamic effects and antitumor efficacy of these treatments were then evaluated. We used tumor cells and autologous PBMCs from patients with varying immunotherapy responses to both model the diversity of immunotherapy efficacy observed in the clinical setting and to recapitulate the heterogeneous nature of melanoma.

RESULTS

Our model exhibited long-term survival of engrafted human PBMCs without developing graft-versus-host disease. Administration of an anti-PD-1 or nemvaleukin elicited antitumor responses in our model that were patient-specific and were found to parallel clinical responsiveness to checkpoint inhibitors. An evaluation of nemvaleukin-treated mice demonstrated increased tumor-infiltrating CD4+ and CD8+ T cells, preferential expansion of non-regulatory T cell subsets in the spleen, and significant delays in tumor growth compared with vehicle-treated controls or mice treated with rhIL-2.

CONCLUSIONS

Our model reproduces differential effects of immunotherapy in melanoma patients, capturing the inherent heterogeneity in clinical responses. Taken together, these data demonstrate our model's translatability for novel immunotherapies in melanoma patients. The data are also supportive for the continued clinical investigation of nemvaleukin as a novel immunotherapeutic for the treatment of melanoma.

Generation of colon cancer-derived tumor-infiltrating T cells (TILs) for adoptive cell therapy

Adoptive cell therapy (ACT) using specific immune cells and stem cells has emerged as a promising treatment option that could complement traditional cancer therapies in the future. In particular, tumor-infiltrating lymphocytes (TILs) have been shown to be effective against solid tumors in various clinical trials. Despite the enormous disease burden and large number of premature deaths caused by colorectal cancer (CRC), studies on TILs isolated from tumor tissue of patients with CRC are still rare. To date, studies on ACT often lack controlled and comparable expansion processes as well as selected ACT-relevant T-cell populations. We describe a procedure for generating patient-specific TILs, which are prerequisites for clinical trials of ACT in CRC. The manufacturing and characteristics of these TILs differ in important modalities from TILs commonly used for this therapeutic approach. Tumor tissue samples were obtained from 12 patients undergoing surgery for primary CRC, predominantly with low microsatellite instability (pMMR-MSI-L). Tumors in the resected specimens were examined pathologically, and an approved volume of tumor tissue was transferred to a disposable perfusion bioreactor. Tissue samples were subjected to an automatically controlled and highly reproducible cultivation process in a GMP-conform, closed perfusion bioreactor system using starting medium containing interleukin-2 and interleukin-12. Outgrowth of TIL from tissue samples was initiated by short-term supplementation with a specific activation cocktail. During subsequent expansion, TILs were grown in interleukin-2-enriched medium. Expansion of TILs in a low-scaled, two-phase process in the Zellwerk ZRP bioreactor under hyperoxic conditions resulted in a number of approximately 2 × 10⁹ cells. The expanded TILs consisted mainly (73%) of the ACT-relevant CD3⁺/CD8⁺ effector memory phenotype (CD45RO⁺/CCR7^-). TILs harvested under these conditions exhibited high functional potential, which was confirmed upon nonspecific stimulation (interferon-γ, tumor necrosis factor-α cytokine assay).

Combination Nivolumab, CD137 Agonism, and Adoptive Cell Therapy with Tumor-Infiltrating Lymphocytes for Patients with Metastatic Melanoma

PURPOSE

Metastatic melanoma is a tumor amenable to immunotherapy in part due to the presence of antigen-specific tumor-infiltrating lymphocytes (TIL). These T cells can be activated and expanded for adoptive cell transfer (ACT), which has resulted in relatively high rates of clinical responses. Similarly, immune checkpoint inhibitors, specifically programmed cell death protein 1 (PD-1) blocking antibodies, augment antitumor immunity and increase the influx of T cells into tumors. Thus, we hypothesized that addition of PD-1 inhibition may improve the outcomes for patients undergoing ACT with TILs.

PATIENTS AND METHODS

Patients with stage III/IV metastatic melanoma with unresectable disease who were anti-PD-1 treatment-naïve were enrolled. TILs were generated in the presence of anti-4-1BB antibody in vitro and expanded for ACT. Patients in cohort 1 received TIL infusion followed by nivolumab. Patients in cohort 2 also received nivolumab prior to surgical harvest and during TIL production.

RESULTS

A total of 11 patients were enrolled, all of whom were evaluated for response, and nine completed ACT. Predominantly CD8+ TILs were successfully expanded from all ACT-treated patients and were tumor reactive in vitro. The trial met its safety endpoint, as there were no protocol-defined dose-limiting toxicity events. The objective response rate was 36%, and median progression-free survival was 5 months. Two nonresponders who developed new metastatic lesions were analyzed to determine potential mechanisms of therapeutic resistance, which included clonal divergence and intrinsic TIL dysfunction.

CONCLUSIONS

Combination therapy with TILs and nivolumab was safe and feasible for patients with metastatic melanoma and provides important insights for future therapeutic developments in ACT with TILs.

Phase I study of adjuvant immunotherapy with autologous tumor-infiltrating lymphocytes in locally advanced cervical cancer

BACKGROUND

Adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TILs) has achieved remarkable clinical efficacy in metastatic cancers such as melanoma and cervical cancer (CC). Here we explored the safety, feasibility and preliminary tumor response and performed translational investigations of adjuvant immunotherapy using infusion of autogenous (auto)-TILs following concurrent chemoradiotherapy (CCRT) in CC patients with locally advanced disease.

METHODS

Twenty-seven CC patients with stage III to IV disease were recruited in this single-center, phase I study. TILs were isolated from lesions in the uterine cervix and generated under good manufacturing practices (GMP) conditions and then infused after CCRT plus intramuscular interleukin (IL)-2 injections.

RESTULTS

From 27 patients, TILs were successfully expanded from 20 patients, with a feasibility of 74.1%. Twelve patients received TILs following CCRT. Adverse events (AEs) were primarily attributable to CCRT. Only 1 (8.3%) patient experienced severe toxicity with a grade 3 hypersensitivity reaction after TIL infusion. No autoimmune AEs, such as pneumonitis, hepatitis, or myocarditis, occurred, and there was no treatment-related mortality. Nine of 12 patients (75.0%) attained complete response, with a disease control duration of 9 to 22 months. Translational investigation showed that the transcriptomic characteristics of the infused TIL products and some immune biomarkers in the tumor microenvironment and serum of CC patients at baseline were correlated with the clinical response.

CONCULSION

TIL-based ACT following CCRT was safe in an academic center setting, with potential effective responses in locally advanced CC patients. 'Hot' inflammatory immune environments are beneficial to the clinical efficacy of TIL-based ACT as adjuvant therapy.

TRIAL REGISTRATION

CLINICALTRIALS

gov NCT04443296.

FUNDING

Natinoal Key R&D Program: Sci-Tech Key Program of the Guangzhou City Science Foundation; the Guangdong Provinve Sci-Tech International Key Program; the National Natural Science Foundation of China.

Neoantigens and their potential applications in tumor immunotherapy

The incidence of malignant tumors is increasing, the majority of which are associated with high morbidity and mortality rates worldwide. The traditional treatment method for malignant tumors is surgery, coupled with radiotherapy or chemotherapy. However, these therapeutic strategies are frequently accompanied with adverse side effects. Over recent decades, tumor immunotherapy shown promise in demonstrating notable efficacy for the treatment of cancer. With the development of sequencing technology and bioinformatics algorithms, neoantigens have become compelling targets for cancer immunotherapy due to high levels of immunogenicity. In addition, neoantigen-based vaccines have demonstrated potential for cancer therapy, primarily by augmenting T-cell responses. Neoantigens have also been shown to be effective in immune checkpoint blockade therapy. Therefore, neoantigens may serve to be predictive biomarkers and synergistic treatment targets in cancer immunotherapy. The aim of the present review was to provide an overview of the recent progress in the classification, screening and clinical application of neoantigens for cancer therapy.

MHC Class I Deficiency in Solid Tumors and Therapeutic Strategies to Overcome It

It is now well accepted that the immune system can control cancer growth. However, tumors escape immune-mediated control through multiple mechanisms and the downregulation or loss of major histocompatibility class (MHC)-I molecules is a common immune escape mechanism in many cancers. MHC-I molecules present antigenic peptides to cytotoxic T cells, and MHC-I loss can render tumor cells invisible to the immune system. In this review, we examine the dysregulation of MHC-I expression in cancer, explore the nature of MHC-I-bound antigenic peptides recognized by immune cells, and discuss therapeutic strategies that can be used to overcome MHC-I deficiency in solid tumors, with a focus on the role of natural killer (NK) cells and CD4 T cells.

Promises and challenges of adoptive T-cell therapies for solid tumours

Cancer is a leading cause of death worldwide and, despite new targeted therapies and immunotherapies, many patients with advanced-stage- or high-risk cancers still die, owing to metastatic disease. Adoptive T-cell therapy, involving the autologous or allogeneic transplant of tumour-infiltrating lymphocytes or genetically modified T cells expressing novel T-cell receptors or chimeric antigen receptors, has shown promise in the treatment of cancer patients, leading to durable responses and, in some cases, cure. Technological advances in genomics, computational biology, immunology and cell manufacturing have brought the aspiration of individualised therapies for cancer patients closer to reality. This new era of cell-based individualised therapeutics challenges the traditional standards of therapeutic interventions and provides opportunities for a paradigm shift in our approach to cancer therapy. Invited speakers at a 2020 symposium discussed three areas-cancer genomics, cancer immunology and cell-therapy manufacturing-that are essential to the effective translation of T-cell therapies in the treatment of solid malignancies. Key advances have been made in understanding genetic intratumour heterogeneity, and strategies to accurately identify neoantigens, overcome T-cell exhaustion and circumvent tumour immunosuppression after cell-therapy infusion are being developed. Advances are being made in cell-manufacturing approaches that have the potential to establish cell-therapies as credible therapeutic options. T-cell therapies face many challenges but hold great promise for improving clinical outcomes for patients with solid tumours.

The Factors Affecting Expansion of Reactive Tumor Infiltrating Lymphocytes (TIL) From Bladder Cancer and Potential Therapeutic Applications

Tumor infiltrating lymphocytes (TIL) therapy was shown to provide durable objective response in patients with metastatic melanoma. As a fundamental first step to bring TIL therapy to clinical use, identification of patients whose tumors yield optimal numbers of reactive TIL is indispensable. We have previously shown that expansion of tumor reactive TIL from primary bladder tumors and lymph node metastases is feasible. Here, we performed TIL harvesting from additional surgical specimens (additional 31 primary tumors and 10 lymph nodes) to generate a heterogenous cohort of 53 patients with bladder cancer (BC) to evaluate the tumor characteristics that lead to tumor-reactive TIL expansion. Among a total of 53 patients, overall TIL growth from tumor samples were 37/53 (69.8%) and overall anti-tumor reactive TIL were 26/35 (74.3%). Mixed urothelial carcinoma is associated with higher anti-tumor reactivity of expanded TIL than pure urothelial carcinoma (89.5% vs. 56.3%, p=0.049). The anti-tumor reactivity of expanded TIL from primary tumors previously treated with BCG immunotherapy were lower (33.3% vs. 82.6%, p=0.027) although T-cell phenotype (CD3+, CD4+, CD8+, and CD56+) was similar regardless prior of BCG therapy. Addition of agonistic 4-1BB antibody in culture media with IL-2 improved the number of expanded TIL from primary tumors previously treated with BCG immunotherapy. There was no significant difference between basal and luminal subtype tumors in terms of viable and reactive TIL growth. Our study demonstrates that TIL expansion is feasible across all BC patients and BC subtypes, and we suggest that TIL therapy can be a reasonable treatment strategy for various manifestations of BC.

BRAF inhibition improves tumor recognition by the immune system: Potential implications for combinatorial therapies against melanoma involving adoptive T-cell transfer

In spite of the fact that they occur at high rates, the clinical responses of BRAF^V600 mutant metastatic melanoma to BRAF inhibitors are usually short-lasting, with most cases progressing within less than 8 mo. Immunomodulatory strategies initiated after progression have recently been reported to be poorly efficient. By characterizing the immunological interactions between T cells and cancer cells in clinical material as well as the influence of the FDA-approved BRAF inhibitor vemurafenib on the immune system, we aimed at unraveling new strategies to expand the efficacy of adoptive T-cell transfer, which represents one of the most promising approaches currently in clinical development for the treatment of metastatic melanoma. Here we show that blocking the BRAF-MAPK pathway in BRAF signaling-addicted melanoma cells significantly increases the ability of T cells contained in clinical grade tumor-infiltrating lymphocytes to recognize autologous BRAF^V600 mutant melanoma cell lines in vitro. Antitumor reactivity was improved regardless of the class of antigen recognized by tumor-specific CD8⁺ T cells. Microarray data suggests that improved tumor recognition is associated with modified expression of MHC Class I-associated proteins as well as of heat-shock proteins. In conclusion, our preclinical data suggest that an appropriately timed sequential treatment of BRAF^V600 mutant melanoma with vemurafenib and adoptive T-cell transfer might result in synergistic antineoplastic effects owing to an increased immunogenicity of cancer cells.

Platforms for Manufacturing Allogeneic, Autologous and iPSC Cell Therapy Products: An Industry Perspective

As cell therapy processes mature from benchtop research protocols to industrial processes capable of manufacturing market-relevant numbers of doses, new cell manufacturing platforms are required. Here we give an overview of the platforms and technologies currently available to manufacture allogeneic cell products, such as mesenchymal stem cells (MSCs) and induced pluripotent stem cells (iPSCs), and technologies for mass production of autologous cell therapies via scale-out. These technologies include bioreactors, microcarriers, cell separation and cryopreservation equipment, molecular biology tools for iPSC generation, and single-use controlled-environment systems for autologous cell production. These platforms address the challenges of manufacturing cell products in greater numbers while maintaining process robustness and product quality.

Anti-tumor activity and mechanism of oligoclonal hepatocellular carcinoma tumor-infiltrating lymphocytes in vivo and in vitro

Objective: To explore a method for culturing hepatocellular carcinoma and tumor-infiltrating lymphocytes (HCC-TIL) and investigate the mechanism of TIL in killing tumors. Methods: The distribution of regulatory T cells (Treg) in HCC was detected by immunohistochemistry. Conventional TIL and oligoclonal TIL were isolated by the traditional method of enzyme digestion combined with mechanical treatment for whole HCC and micro HCC tissue block culturing method. MTT was used to compare the killing activity of TIL. Flow cytometry was used to analyze the proportion of CD8⁺ T cells and Treg cells in TIL. Tumor-bearing mice were established, and TIL adoptive immunotherapy was performed. Results: Treg cells were mainly distributed in the stroma of HCC. In vitro experiments showed oligoclonal TIL had higher cytotoxicity to tumor cells which negatively correlated with the proportion of Treg cells. In vivo experiments showed oligoclonal TIL had a higher anti-tumor effect. IFN-γ in peripheral blood and the positive rate of intratumoral lymphocytic infiltration in oligoclonal TIL group were both higher. TGF-β and IL-10 in peripheral blood and the positive rate of intratumoral FoxP3 and IL-17 were both lower than those in conventional TIL group. Conclusion: The oligoclonal TIL culture method could obtain TIL with higher purity, and cytotoxicity to tumor cells was associated with Treg cells. The oligoclonal TIL had cytotoxicity to autologous HCC cells and significant inhibitory effect on the growth of transplanted tumors. The mechanism might be associated with the inhibition of Treg cells proliferation, increase of IFN-γ secretion, and decrease of TGF-β, IL-10, and IL-17 secretion.

Adoptive cell transfer using autologous tumor infiltrating lymphocytes in gynecologic malignancies

During the last decade, the field of cancer immunotherapy has been entirely transformed by the development of new and more effective treatment modalities with impressive response rates and the prospect of long survival. One of the major breakthroughs is adoptive cell transfer (ACT) based on autologous T cells derived from tumor-infiltrating lymphocytes (TILs). TIL-based ACT is a highly personalized cancer treatment. T cells are harvested from autologous fresh tumor tissues, and after ex vivo activation and extensive expansion, are reinfused to patients. TIL-based therapies have only been offered in small phase I/II studies in a few centers given the highly specialized care required, the complexity of TIL production and the very intensive nature of the three-step treatment protocol. The treatment includes high-dose lymphodepleting chemotherapy, the infusion of the expanded and activated T cells and interleukin-2 (IL-2) injections to increase survival of the T cells. Despite the limited data on ACT, the small published studies consistently confirm an impressive clinical response rate of up to 50% in metastatic melanoma patients, including a significant proportion of patients with durable complete response. These remarkable results justify the need for larger clinical trials in other solid tumors, including gynecologic malignancies. In this review we provide an overview of the current clinical results, future applications of TIL-based ACT in gynecologic malignancies, and on risks and challenges associated with modern T cell therapy.

Immunotherapy combination strategies (non-chemotherapy) in non-small cell lung cancer

Immune checkpoint inhibitors enhance the activation and antitumor activity of the immune system, resulting in durable response rates in a select group of patients. Cytotoxic T lymphocyte antigen 4 (CTLA4) inhibitors target the inhibitory interaction between CTLA4 and CD80 or CD86. Programmed death 1 (PD1) inhibitors target the interaction between PD1 receptors on T-cells and PD-ligand 1 (PD-L1) and PD-ligand 2, blocking the inhibitory signaling and resulting in activation of T-cell effector function. These therapeutic drugs were originally evaluated in patients with metastatic melanoma before expansion to all tumor types, including non-small cell lung cancer (NSCLC) with promising results. The PD1 inhibitors such as pembrolizumab have now received FDA approval in the first-line setting for patients with positive PD-L1 expression tumor types; however, only a portion of patients have shown objective and sustainable responses. To expand the number of patients with observed response to immunotherapeutic agents including patients with negative PD-L1 expression tumors, clinical trials are ongoing to assess the safety and efficacy of combination immune checkpoint inhibitors and combination immune checkpoint inhibitors with targeted therapy. Immune checkpoint inhibitors have been found to be a promising therapeutic drug class with sustainable response rates and a tolerable safety profile, and efforts continue to improve these drugs in patients with NSCLC.

Janus Iron Oxides @ Semiconducting Polymer Nanoparticle Tracer for Cell Tracking by Magnetic Particle Imaging

Iron oxides nanoparticles tailored for magnetic particle imaging (MPI) have been synthesized, and their MPI signal intensity is three-times that of commercial MPI contrast (Ferucarbotran, also called Vivotrax) and seven-times that of MRI contrast (Feraheme) at the same Fe concentration. MPI tailored iron oxide nanoparticles were encapsulated with semiconducting polymers to produce Janus nanoparticles that possessed optical and magnetic properties for MPI and fluorescence imaging. Janus particles were applied to cancer cell labeling and in vivo tracking, and as few as 250 cells were imaged by MPI after implantation, corresponding to an amount of 7.8 ng of Fe. Comparison with MRI and fluorescence imaging further demonstrated the advantages of our Janus particles for MPI-super sensitivity, unlimited tissue penetration, and linear quantitativity.

A First-in-Human Phase I Study of Subcutaneous Outpatient Recombinant Human IL15 (rhIL15) in Adults with Advanced Solid Tumors

Purpose: Preclinical data established IL15 as a homeostatic factor and powerful stimulator of NK and CD8⁺ T-cell function, the basis for clinical testing.Experimental Design: A first-in-human outpatient phase I dose escalation trial of subcutaneous (SC) rhIL15 was conducted in refractory solid tumor cancer patients. Therapy consisted of daily (Monday-Friday) subcutaneous injections of rhIL15 for two consecutive weeks (10 total doses/cycle). Clinical response was assessed by RECIST. Pharmacokinetics of rhIL15 and immune biomarkers were evaluated.Results: Nineteen patients were treated with rhIL15 at dose levels of 0.25, 0.5, 1, 2, and 3 mcg/kg/day. Fourteen patients completed ≥ 2 cycles of therapy that was well tolerated. One serious adverse event (SAE), grade 2 pancreatitis, required overnight hospitalization. Enrollment was halted after a patient receiving 3 mcg/kg/day developed a dose-limiting SAE of grade 3 cardiac chest pain associated with hypotension and increased troponin. No objective responses were observed; however, several patients had disease stabilization including a renal cell carcinoma patient who continued protocol treatment for 2 years. The treatment induced profound expansion of circulating NK cells, especially among the CD56^bright subset. A proportional but less dramatic increase was found among circulating CD8⁺ T cells with maximal 3-fold expansion for the 2 and 3 mcg/kg patients.Conclusions: SC rhIL15 treatment was well tolerated, producing substantial increases in circulating NK and CD8⁺ T cells. This protocol establishes a safe outpatient SC rhIL15 regimen of 2 mcg/kg/day dosing amenable to self-injection and with potential as a combination immunotherapeutic agent. Clin Cancer Res; 24(7); 1525-35. ©2017 AACR.

Adoptive cell therapy with CD4+ T helper 1 cells and CD8+ cytotoxic T cells enhances complete rejection of an established tumour, leading to generation of endogenous memory responses to non-targeted tumour epitopes

The results of adoptive T-cell therapies (ACTs) are very encouraging and show clinical evidence that ACT can provide a cure for patients with metastatic disease. However, various response rates and long-term cancer remission have been observed in different ACT trials. The types of T cells, prior treatment with chemotherapy and co-administration of other immune-target therapies have been found to influence the efficacy of ACT. In this study, we investigate the ability of ACT using CD4⁺ T helper 1 (Th1) cells and CD8⁺ cytotoxic T lymphocytes (CTLs) to reject the growth of established B16-ovalbumin (OVA) melanoma. CD8⁺ CTLs were found to be the main effector T cells that mediated tumour regression. However, low tumour-free survival rates were observed in ACT with CD8⁺ CTLs only. Co-transferring CD4⁺ Th1 cells and CD8⁺ CTLs has been observed to induce a synergistic antitumour response, resulting in complete regression in 80% of the tumour-bearing mice. We also examined a prior Dacarbazine (DTIC) and after virus-like particle (VLP)-OVA vaccine treatment to enhance ACT, but no therapeutic benefit was observed during primary B16-OVA tumour growth. Nevertheless, the ACT-mediated antitumour response was able to generate memory responses to both B16-OVA and B16-gp33 tumours. VLP-OVA vaccination following ACT enhances the memory responses to tumours that express a heterogenic population of both B16-OVA and B16-gp33 cells; however, it abolished the memory response to tumours consisting of only gp33-expressing cells. These findings provide important information for designing therapeutic treatments for patients with metastatic disease and cancer relapse to achieve durable cancer remission.

Stereotactic radiosurgery and immunotherapy for metastatic spinal melanoma

The management of metastatic spinal melanoma involves maximizing local control, preventing recurrence, and minimizing treatment-associated toxicity and spinal cord damage. Additionally, therapeutic measures should promote mechanical stability, facilitate rehabilitation, and promote quality of life. These objectives prove difficult to achieve given melanoma's elusive nature, radioresistant and chemoresistant histology, vascular character, and tendency for rapid and early metastasis. Different therapeutic modalities exist for metastatic spinal melanoma treatment, including resection (definitive, debulking, or stabilization procedures), stereotactic radiosurgery, and immunotherapeutic techniques, but no single treatment modality has proven fully effective. The authors present a conceptual overview and critique of these techniques, assessing their effectiveness, separately and combined, in the treatment of metastatic spinal melanoma. They provide an up-to-date guide for multidisciplinary treatment strategies. Protocols that incorporate specific, goal-defined surgery, immunotherapy, and stereotactic radiosurgery would be beneficial in efforts to maximize local control and minimize toxicity.

Metastatic melanoma treatment: Combining old and new therapies

Metastatic melanoma is an aggressive form of cancer characterised by poor prognosis and a complex etiology. Until 2010, the treatment options for metastatic melanoma were very limited. Largely ineffective dacarbazine, temozolamide or fotemustine were the only agents in use for 35 years. In recent years, the development of molecularly targeted inhibitors in parallel with the development of checkpoint inhibition immunotherapies has rapidly improved the outcomes for metastatic melanoma patients. Despite these new therapies showing initial promise; resistance and poor duration of response have limited their effectiveness as monotherapies. Here we provide an overview of the history of melanoma treatment, as well as the current treatments in development. We also discuss the future of melanoma treatment as we go beyond monotherapies to a combinatorial approach. Combining older therapies with the new molecular and immunotherapies will be the most promising way forward for treatment of metastatic melanoma.

Characterization and comparison of 'standard' and 'young' tumour-infiltrating lymphocytes for adoptive cell therapy at a Danish translational research institution

Adoptive cell therapy (ACT) with ex vivo expanded tumour-infiltrating lymphocytes (TILs) in combination with IL-2 is an effective treatment for metastatic melanoma. Modified protocols of cell expansion may allow the treatment of most enrolled patients and improve the efficacy of adoptively transferred cells. The aims of this study were to establish and validate the novel 'Young TIL' method at our institution and perform a head-to-head comparison of clinical-grade products generated with this protocol opposed to the conventional 'Standard TIL', which we are currently using in a pilot ACT trial for patients with melanoma. Our results confirm that 'Young TILs' display an earlier differentiation state, with higher CD27 and lower CD56 expression. In addition, CD8(+) TILs expressing CD27 had longer telomeres compared with the CD27(-). A recently described subset of NK cells, endowed with a high expression of CD56 (CD56(bright)), was detected for the first time in both types of cultures but at a higher frequency on Young TILs. Young and Standard TILs' reactivity against autologous tumours was similar, with significant expression of TNF-α/IFN-γ/CD107a by CD8(+) TILs detected in all cultures analysed. However, either slow expansion with high-dose IL-2 only or large numerical expansion with a rapid expansion protocol, which is required for current therapeutic protocols, significantly modified TIL phenotype by reducing the frequency of less differentiated, cancer-specific TILs. These studies further support the adoption of the Young TIL method in our current ACT trial and highlight the importance of continuous quality control of expansion protocols.

Nanomedicine for Cancer Immunotherapy: Tracking Cancer-Specific T-Cells in Vivo with Gold Nanoparticles and CT Imaging

Application of immune cell-based therapy in routine clinical practice is challenging due to the poorly understood mechanisms underlying success or failure of treatment. Development of accurate and quantitative imaging techniques for noninvasive cell tracking can provide essential knowledge for elucidating these mechanisms. We designed a novel method for longitudinal and quantitative in vivo cell tracking, based on the superior visualization abilities of classical X-ray computed tomography (CT), combined with state-of-the-art nanotechnology. Herein, T-cells were transduced to express a melanoma-specific T-cell receptor and then labeled with gold nanoparticles (GNPs) as a CT contrast agent. The GNP-labeled T-cells were injected intravenously to mice bearing human melanoma xenografts, and whole-body CT imaging allowed examination of the distribution, migration, and kinetics of T-cells. Using CT, we found that transduced T-cells accumulated at the tumor site, as opposed to nontransduced cells. Labeling with gold nanoparticles did not affect T-cell function, as demonstrated both in vitro, by cytokine release and proliferation assays, and in vivo, as tumor regression was observed. Moreover, to validate the accuracy and reliability of the proposed cell tracking technique, T-cells were labeled both with green fluorescent protein for fluorescence imaging, and with GNPs for CT imaging. A remarkable correlation in signal intensity at the tumor site was observed between the two imaging modalities, at all time points examined, providing evidence for the accuracy of our CT cell tracking abilities. This new method for cell tracking with CT offers a valuable tool for research, and more importantly for clinical applications, to study the fate of immune cells in cancer immunotherapy.

Genetically modified T cells in cancer therapy: opportunities and challenges

Tumours use many strategies to evade the host immune response, including downregulation or weak immunogenicity of target antigens and creation of an immune-suppressive tumour environment. T cells play a key role in cell-mediated immunity and, recently, strategies to genetically modify T cells either through altering the specificity of the T cell receptor (TCR) or through introducing antibody-like recognition in chimeric antigen receptors (CARs) have made substantial advances. The potential of these approaches has been demonstrated in particular by the successful use of genetically modified T cells to treat B cell haematological malignancies in clinical trials. This clinical success is reflected in the growing number of strategic partnerships in this area that have attracted a high level of investment and involve large pharmaceutical organisations. Although our understanding of the factors that influence the safety and efficacy of these therapies has increased, challenges for bringing genetically modified T-cell immunotherapy to many patients with different tumour types remain. These challenges range from the selection of antigen targets and dealing with regulatory and safety issues to successfully navigating the routes to commercial development. However, the encouraging clinical data, the progress in the scientific understanding of tumour immunology and the improvements in the manufacture of cell products are all advancing the clinical translation of these important cellular immunotherapies.

Phase I trial of adoptively transferred tumor-infiltrating lymphocyte immunotherapy following concurrent chemoradiotherapy in patients with locoregionally advanced nasopharyngeal carcinoma

Adoptive cell therapy (ACT) for cancers using autologous tumor-infiltrating lymphocytes (TILs) can induce immune responses and antitumor activity in metastatic melanoma patients. Here, we aimed to assess the safety and antitumor activity of ACT using expanded TILs following concurrent chemoradiotherapy (CCRT) in patients with locoregionally advanced nasopharyngeal carcinoma (NPC). Twenty-three newly diagnosed, locoregionally advanced NPC patients were enrolled, of whom 20 received a single-dose of TIL infusion following CCRT. All treated patients were assessed for toxicity, survival and clinical and immunologic responses. Correlations between immunological responses and treatment effectiveness were further studied. Only mild adverse events (AEs), including Grade 3 neutropenia (1/23, 5%) consistent with immune-related causes, were observed. Nineteen of 20 patients exhibited an objective antitumor response, and 18 patients displayed disease-free survival longer than 12 mo after ACT. A measurable plasma Epstein-Barr virus (EBV) load was detected in 14 patients at diagnosis, but a measurable EBV load was not found in patients after one week of ACT, and the plasma EBV load remained undetectable in 17 patients at 6 mo after ACT. Expansion and persistence of T cells specific for EBV antigens in peripheral blood following TIL therapy were observed in 13 patients. The apparent positive correlation between tumor regression and the expansion of T cells specific for EBV was further investigated in four patients. This study shows that NPC patients can tolerate ACT with TILs following CCRT and that this treatment results in sustained antitumor activity and anti-EBV immune responses. A larger phase II trial is in progress.

Notch signaling regulates antigen sensitivity of naive CD4+ T cells by tuning co-stimulation

Adaptive immune responses begin when naive CD4(+) T cells engage peptide+major histocompatibility complex class II and co-stimulatory molecules on antigen-presenting cells (APCs). Notch signaling can influence effector functions in differentiated CD4(+) T helper and T regulatory cells. Whether and how ligand-induced Notch signaling influences the initial priming of CD4(+) T cells has not been addressed. We have found that Delta Like Ligand 4 (DLL4)-induced Notch signaling potentiates phosphatidylinositol 3-OH kinase (PI3K)-dependent signaling downstream of the T cell receptor+CD28, allowing naive CD4(+) T cells to respond to lower doses of antigen. In vitro, DLL4-deficient APCs were less efficient stimulators of CD4(+) T cell activation, metabolism, proliferation, and cytokine secretion. With deletion of DLL4 from CD11c(+) APCs in vivo, these deficits translated to an impaired ability to mount an effective CD4(+)-dependent anti-tumor response. These data implicate Notch signaling as an important regulator of adaptive immune responses.

Achievements and challenges of adoptive T cell therapy with tumor-infiltrating or blood-derived lymphocytes for metastatic melanoma: what is needed to achieve standard of care?

Adoptive cell therapy (ACT) based on autologous T cell derived either from tumor as tumor-infiltrating lymphocytes (TILs) or from peripheral blood is developing as a key area of future personalized cancer therapy. TIL-based ACT is defined as the infusion of T cells harvested from autologous fresh tumor tissues after ex vivo activation and extensive expansion. TIL-based ACT has so far only been tested in smaller phase I/II studies, but these studies consistently confirm an impressive clinical response rate of up to 50 % in metastatic melanoma including a significant proportion of patients with durable complete tumor eradication. These remarkable results justify the need for a definitive phase III trial documenting the efficacy of this type of T cell-based Advanced Therapy Medicinal Product in order to pave the way for regulatory approval and implementation of TIL therapy as a new treatment standard in oncology practice. TIL-based ACT can, however, only be offered to a limited group of patients based on the need for accessible tumor tissue, the complexity of TIL production procedures, and the very intensive nature of this three-step treatment including both high-dose chemotherapy and interleukin-2 in addition to T cell infusion. To this end, adoptive T cell therapy using peripheral blood mononuclear cell-derived T cells could be a welcome alternative to circumvent these limitations and broaden up the applicability of ACT. Here, we discuss current initiatives in this focused research review.

Large-scale expansion of γδ T cells and peptide-specific cytotoxic T cells using zoledronate for adoptive immunotherapy

Specific cellular immunotherapy for cancer requires efficient generation and expansion of cytotoxic T lymphocytes (CTLs) that recognize tumor-associated antigens. However, it is difficult to isolate and expand functionally active T-cells ex vivo. In this study, we investigated the efficacy of a new method to induce expansion of antigen-specific CTLs for adoptive immunotherapy. We used tumor-associated antigen glypican-3 (GPC3)-derived peptide and cytomegalovirus (CMV)-derived peptide as antigens. Treatment of human peripheral blood mononuclear cells (PBMCs) with zoledronate is a method that enables large-scale γδ T-cell expansion. To induce expansion of γδ T cells and antigen-specific CTLs, the PBMCs of healthy volunteers or patients vaccinated with GPC3 peptide were cultured with both peptide and zoledronate for 14 days. The expansion of γδ T cells and peptide-specific CTLs from a few PBMCs using zoledronate yields cell numbers sufficient for adoptive transfer. The rate of increase of GPC3-specific CTLs was approximately 24- to 170,000-fold. These CD8⁺ cells, including CTLs, showed GPC3-specific cytotoxicity against SK-Hep-1/hGPC3 and T2 pulsed with GPC3 peptide, but not against SK-Hep-1/vec and T2 pulsed with human immunodeficiency virus peptide. On the other hand, CD8⁻ cells, including γδ T cells, showed cytotoxicity against SK-Hep-1/hGPC3 and SK-Hep-1/vec, but did not show GPC3 specificity. Furthermore, adoptive cell transfer of CD8⁺ cells, CD8⁻ cells, and total cells after expansion significantly inhibited tumor growth in an NOD/SCID mouse model. This study indicates that simultaneous expansion of γδ T cells and peptide-specific CTLs using zoledronate is useful for adoptive immunotherapy.

Human immunity in vitro - solving immunogenicity and more

It has been widely recognised that the phylogenetic distance between laboratory animals and humans limits the former's predictive value for immunogenicity testing of biopharmaceuticals and nanostructure-based drug delivery and adjuvant systems. 2D in vitro assays have been established in conventional culture plates with little success so far. Here, we detail the status of various 3D approaches to emulate innate immunity in non-lymphoid organs and adaptive immune response in human professional lymphoid immune organs in vitro. We stress the tight relationship between the necessarily changing architecture of professional lymphoid organs at rest and when activated by pathogens, and match it with the immunity identified in vitro. Recommendations for further improvements of lymphoid tissue architecture relevant to the development of a sustainable adaptive immune response in vitro are summarized. In the end, we sketch a forecast of translational innovations in the field to model systemic innate and adaptive immunity in vitro.

Latest advances in chemotherapeutic, targeted, and immune approaches in the treatment of metastatic melanoma

Melanoma is the most dangerous form of skin cancer owing to its metastatic potential and is an important public health concern. The melanoma incidence has been increasing worldwide. Although potentially curable when diagnosed early, metastatic melanoma carries a poor prognosis. Until recently, systemic therapy for metastatic melanoma was ineffective, but the recent successes in the development of new therapies for metastatic melanoma, such as mitogen-activated protein kinase (MAPK) pathway inhibitors, anti-cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), and programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway blocking antibodies, as well as combination strategies of cytotoxic chemotherapy and inhibitors of angiogenesis, have all yielded promising results, changing the continually evolving landscape of therapeutic options for patients with this disease. The aim of this review was to summarize the evolution of and recent advances in the treatment of metastatic melanoma. Therefore, we conducted a comprehensive PubMed search between January 1, 1960, and February 1, 2014, using the search term melanoma or metastatic melanoma combined with terms such as chemotherapy, immunotherapy, CTLA-4, PD-1, PD-L1, adoptive T cell, targeted therapy, MAPK, molecular biology, and survival.

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.

Dendritic cells in cancer immunotherapy: vaccines and combination immunotherapies

Dendritic cells (DCs) are specialized immunostimulatory cells involved in the induction and regulation of immune responses. The feasibility of large-scale ex vivo generation of DCs from patients' monocytes allows for therapeutic application of ex vivo-cultured DCs to bypass the dysfunction of endogenous DCs, restore immune surveillance, induce cancer regression or stabilization or delay or prevent its recurrence. While the most common paradigm of the therapeutic application of DCs reflects their use as cancer 'vaccines', additional and potentially more effective possibilities include the use of patients' autologous DCs as parts of more comprehensive therapies involving in vivo or ex vivo induction of tumor-reactive T cells and the measures to counteract systemic and local immunosuppression in tumor-bearing hosts. Ex vivo-cultured DCs can be instructed to acquire distinct functions relevant for the induction of effective cancer immunity (DC polarization), such as the induction of different effector functions or different homing properties of tumor-specific T cells (delivery of 'signal 3' and 'signal 4'). These considerations highlight the importance of the application of optimized conditions for the ex vivo culture of DCs and the potential combination of DC therapies with additional immune interventions to facilitate the entry of DC-induced T cells to tumor tissues and their local antitumor functions.

Phenotype and function of T cells infiltrating visceral metastases from gastrointestinal cancers and melanoma: implications for adoptive cell transfer therapy

Adoptive cell transfer of tumor-infiltrating lymphocytes (TILs) can mediate cancer regression in patients with metastatic melanoma, but whether this approach can be applied to common epithelial malignancies remains unclear. In this study, we compared the phenotype and function of TILs derived from liver and lung metastases from patients with gastrointestinal (GI) cancers (n = 14) or melanoma (n = 42). Fewer CD3(+) T cells were found to infiltrate GI compared with melanoma metastases, but the proportions of CD8(+) cells, T cell differentiation stage, and expression of costimulatory molecules were similar for both tumor types. Clinical-scale expansion up to ~50 × 10(9) T cells on average was obtained for all patients with GI cancer and melanoma. From GI tumors, however, TIL outgrowth in high-dose IL-2 yielded 22 ± 1.4% CD3(+)CD8(+) cells compared with 63 ± 2.4% from melanoma (p < 0.001). IFN-γ ELISA demonstrated MHC class I-mediated reactivity of TIL against autologous tumor in 5 of 7 GI cancer patients tested (9% of 188 distinct TIL cultures) and in 9 of 10 melanoma patients (43% of 246 distinct TIL cultures). In these assays, MHC class I-mediated up-regulation of CD137 (4-1BB) expression on CD8(+) cells suggested that 0-3% of TILs expanded from GI cancer metastases were tumor-reactive. This study implies that the main challenge to the development of TIL adoptive cell transfer for metastatic GI cancers may not be the in vitro expansion of bulk TILs, but the ability to select and enrich for tumor-reactive T cells.

Cancer immunotherapy: current status and future directions

Better understanding of the underlying principles of tumor biology and immunology, enhanced by recent insights into the mechanisms of immune recognition, regulation, and tumor escape has provided new approaches for cancer immunotherapy. This article reviews the current status and future directions of cancer immunotherapy, with a focus on the recent encouraging results from immune-modulating antibodies and adoptive cell therapy.

Extranodal induction of therapeutic immunity in the tumor microenvironment after intratumoral delivery of Tbet gene-modified dendritic cells

Murine dendritic cells (DC) transduced to express the Type-1 transactivator T-bet (i.e. mDC.Tbet) and delivered intratumorally as a therapy are superior to control wild-type DC in slowing the growth of established subcutaneous MCA205 sarcomas in vivo. Optimal antitumor efficacy of mDC.Tbet-based gene therapy was dependent on host natural killer (NK) cells and CD8(+) T cells, and required mDC.Tbet expression of major histocompatibility complex class I molecules, but was independent of the capacity of the injected mDC.Tbet to produce proinflammatory cytokines (interleukin-12 family members or interferon-γ) or to migrate to tumor-draining lymph nodes based on CCR7 ligand chemokine recruitment. Conditional (CD11c-DTR) or genetic (BATF3(-/-)) deficiency in host antigen-crosspresenting DC did not diminish the therapeutic action of intratumorally delivered wild-type mDC.Tbet. Interestingly, we observed that intratumoral delivery of mDC.Tbet (versus control mDC.Null) promoted the acute infiltration of NK cells and naive CD45RB(+) T cells into the tumor microenvironment (TME) in association with elevated expression of NK- and T-cell-recruiting chemokines by mDC.Tbet. When taken together, our data support a paradigm for extranodal (cross)priming of therapeutic Type-1 immunity in the TME after intratumoral delivery of mDC.Tbet-based gene therapy.

Local immune response predicts survival in patients with thick (t4) melanomas

BACKGROUND

Tumor infiltrating lymphocytes (TIL) and histological regression in primary melanoma are generally considered indicators of the local immune response but their roles as prognostic factors have been variably reported. We examined the prognostic role of these variables in patients with high risk (T4) primary melanomas in a large series of patients with long-term follow-up.

METHODS

From a prospectively maintained cohort of patients diagnosed between 1971 and 2004, 161 patients were retrospectively identified with primary thick melanomas (>4 mm), no clinical evidence of regional nodal disease (RND) at diagnosis and complete histopathologic data. Univariate and multivariate Cox regression models were performed to identify clinical and histopathologic predictors of disease-specific survival (DSS) and to identify subgroups with differential survival.

RESULTS

Factors significantly associated with decreased DSS by univariate analysis included male gender, age ≥ 60 years, axial anatomic location, presence of ulceration, RND, absence of TIL, and presence of regression. In the final multivariate model, TIL and regression, as interacting variables, and RND status remained significantly associated with DSS. In the presence of TIL, concomitant regression was associated with significantly worse survival (p ≤ 0.0001). In the absence of TIL, there was no effect of regression on survival (p = 0.324).

CONCLUSIONS

Primary TIL and regression status and RND status are independently associated with melanoma-specific survival in patients with T4 melanomas; presence of TIL in the primary melanoma with concomitant radial growth phase regression is associated with a poor prognosis and may reflect an ineffective local regional immune response.

Exploring dendritic cell based vaccines targeting survivin for the treatment of head and neck cancer patients

Background

New treatment modalities are needed for the treatment of cancers of the head and neck region (HNSCC). Survivin is important for the survival and proliferation of tumor cells and may therefore provide a target for immunotherapy. Here we focused on the ex vivo presence and in vitro induction of survivin specific T cells.

Methods

Tetramer staining and ELIspot assays were used to document the presence of survivin specific T cells in patient derived material, and to monitor the presence and persistence of survivin specific T cells after repeated in vitro stimulation with autologous dendritic cells.

Results

Ex vivo analysis showed the presence of survivin-specific T cells in the peripheral blood (by tetramer analysis) and in the draining lymph node (by ELIspot analysis) in a HNSCC and a locally advanced breast cancer patient respectively. However, we were unable to maintain isolated survivin specific T cells for prolonged periods of time. For the in vitro generation of survivin specific T cells, monocyte derived DC were electroporated with mRNA encoding full length survivin or a survivin mini-gene together with either IL21 or IL12 mRNA. Western blotting and immunohistochemical staining of dendritic cell cytospin preparations confirmed translation of the full length survivin protein. After repeated stimulation we observed an increase, followed by a decrease, of the number of survivin specific T cells. FACS sorted or limiting dilution cloned survivin specific T cells could not be maintained on feeder mix for prolonged periods of time. Protein expression analysis subsequently showed that activated, but not resting T cells contain survivin protein.

Conclusions

Here we have shown that survivin specific T cells can be detected ex vivo in patient derived material. Furthermore, survivin specific T cells can be induced in vitro using autologous dendritic cells with enforced expression of survivin and cytokines. However, we were unable to maintain enriched or cloned survivin specific T cells for prolonged periods of time. Endogenous expression of survivin in activated T cells and subsequent fratricide killing might explain our in vitro observations. We therefore conclude that survivin, although it is a universal tumor antigen, might not be the ideal target for immunotherapeutic strategies for the treatment of cancer of the head and neck.

Young T Cells Age During a Redirected Anti-Tumor Attack: Chimeric Antigen Receptor-Provided Dual Costimulation is Half the Battle

Adoptive therapy with chimeric antigen receptor (CAR)-redirected T cells showed spectacular efficacy in the treatment of leukemia in recent early phase trials. Patient’s T cells were ex vivo genetically engineered with a CAR, amplified and re-administered to the patient. While T cells mediating the primary response were predominantly of young effector and central memory phenotype, repetitive antigen engagement irreversible triggers T cell maturation leaving late memory cells with the KLRG1⁺ CD57⁺ CD7⁻ CCR7⁻ phenotype in the long-term. These cells preferentially accumulate in the periphery, are hypo-responsive upon TCR engagement and prone to activation-induced cell death. A recent report indicates that those T cells can be rescued by CAR provided CD28 and OX40 (CD134) stimulation. We discuss the strategy with respect to prolong the anti-tumor response and to improve the over-all efficacy of adoptive cell therapy.

Adoptive cellular immunotherapy in metastatic renal cell carcinoma: a systematic review and meta-analysis

Purpose

Metastatic renal cell carcinoma (mRCC), as one of the most immunogenic tumors has been the focus of adoptive cellular immunotherapy (ACI), but the effects of ACI on objective response and survival in patients with mRCC are still controversial. Therefore, a systematic review and meta-analysis was performed to address this issue.

Methods

A search was conducted in the PubMed database for randomized clinical trials (RCTs) with ACI in mRCC. All included articles in this study were assessed according to the selection criteria and were divided into two groups: ACI versus no ACI. Outcomes were toxicity, objective response, 1-, 3- and 5-year survival. Risk ratio (RR) and 95% confidence intervals (CI) were calculated using a fixed-effects meta-analysis. Heterogeneity was measured by value of I² or P.

Results

4 studies (469 patients) were included. Most of ACI-related adverse reactions were grade 1 or 2 and reversible. ACI provided significant benefit in terms of objective response (RR = 1.65; 95% CI, 1.15 to 2.38; P = 0.007, I² = 49%), 1-year survival (RR = 1.30; 95% CI, 1.12 to 1.52; P = 0.0008, I² = 0%), 3-year survival (RR = 2.76; 95% CI, 1.85 to 4.14; P<0.00001, I² = 46%) and 5-year survival (RR = 2.42; 95% CI, 1.21 to 4.83; P = 0.01, I² = 28%).

Conclusions

ACI may be a safe and effective treatment for improving objective response, 1-, 3- and 5-year survival in patients with mRCC. Besides, five obstacles for ACI, including high degree of personalization, unsuitable WHO/RECIST response criteria, inadequate identification of tumor-associated antigens (TAAs), lack of effective combination treatments and less attention paid to the quality of ACI products, should be overcome during the successful development of more potent ACI for cancer in the future.

T-cell receptor affinity and avidity defines antitumor response and autoimmunity in T-cell immunotherapy

T cells expressing antigen-specific T-cell receptors (TCRs) can mediate effective tumor regression, but they often also are accompanied by autoimmune responses. To determine the TCR affinity threshold defining the optimal balance between effective antitumor activity and autoimmunity in vivo, we used a unique self-antigen system comprising seven human melanoma gp100(209-217)-specific TCRs spanning physiological affinities (1-100 μM). We found that in vitro and in vivo T-cell responses are determined by TCR affinity, except in one case that was compensated by substantial CD8 involvement. Strikingly, we found that T-cell antitumor activity and autoimmunity are closely coupled but plateau at a defined TCR affinity of 10 µM, likely due to diminished contribution of TCR affinity to avidity above the threshold. Together, these results suggest that a relatively low-affinity threshold is necessary for the immune system to avoid self-damage, given the close relationship between antitumor activity and autoimmunity. The low threshold, in turn, indicates that adoptive T-cell therapy treatment strategies using in vitro-generated high-affinity TCRs do not necessarily improve efficacy.

Tumor-infiltrating lymphocytes in melanoma

Adoptive cell therapy using tumor-infiltrating lymphocytes (TIL) is arguably the most effective treatment for patients with metastatic melanoma. With higher response rates than ipilimumab or IL-2, and longer durations of response than vemurafenib, TIL therapy carries the potential to transform current outcomes in melanoma, while also defining the way cell-based immunotherapy gets incorporated into mainstream cancer treatment. This paper will review the current state of TIL therapy in melanoma, the strategies to improve its efficacy, the current obstacles, and future directions to expand the availability of TIL to the general patient population.

HDAC inhibition suppresses primary immune responses, enhances secondary immune responses, and abrogates autoimmunity during tumor immunotherapy

Histone deacetylase inhibitors (HDACi) can modulate innate antiviral responses and render tumors more susceptible to oncolytic viruses (OVs); however, their effects on adaptive immunity in this context are largely unknown. Our present study reveals an unexpected property of the HDACi MS-275 that enhances viral vector-induced lymphopenia leading to selective depletion of bystander lymphocytes and regulatory T cells while allowing expansion of antigen-specific secondary responses. Coadministration of vaccine plus drug during the boosting phase focuses the immune response on the tumor by suppressing the primary immune response against the vaccine vector and enhancing the secondary response against the tumor antigen. Furthermore, improvement of T cell functionality was evident suggesting that MS-275 can orchestrate a complex array of effects that synergize immunotherapy and viral oncolysis. Surprisingly, while MS-275 dramatically enhanced efficacy, it suppressed autoimmune pathology, profoundly improving the therapeutic index.

Biomarkers and correlative endpoints for immunotherapy trials

Immunotherapies for lung cancer are reaching phase III clinical trial, but the ultimate success likely will depend on developing biomarkers to guide development and choosing patient populations most likely to benefit. Because the immune response to cancer involves multiple cell types and cytokines, some spatially and temporally separated, it is likely that multiple biomarkers will be required to fully characterize efficacy of the vaccine and predict eventual benefit. Peripheral blood markers of response, such as the ELISPOT assay and cytokine flow cytometry analyses of peripheral blood mononuclear cells following immunotherapy, remain the standard approach, but it is increasingly important to obtain tissue to study the immune response at the site of the tumor. Earlier clinical endpoints such as response rate and progression-free survival do not correlate with overall survival demonstrated for some immunotherapies, suggesting the need to develop other intermediary clinical endpoints. Insofar as all these biomarkers and surrogate endpoints are relevant in multiple malignancies, it may be possible to extrapolate findings to immunotherapy of lung cancer.

Adoptive immunotherapy of advanced melanoma

Adoptive cell therapy (ACT) has emerged as an effective therapy for patients with metastatic melanoma. Since the first introduction of the protocol in 1988 [1], major improvements have been achieved with response rates of 40%-72% among patients who were resistant to previous treatment lines. Both cell product and conditioning regimen are major determinants of treatment efficacy; therefore, developing ACT protocols explore diverse ways to establish autologous intra-tumoral lymphocyte cultures or peripheral effector cells as well as different lymphodepleting regimens. While a proof of feasibility and a proof of concept had been established with previous published results, ACT will need to move beyond single-center experiences, to confirmatory, multi-center studies. If ACT is to move into widespread practice, it will be necessary to develop reproducible high quality cell production methods and accepted lymphodepleting regimen. Two new drugs, ipilimumab (Yervoy, Bristol-Myers Squibb) and vemurafenib (Zelboraf, Roche), were approved in 2011 for the treatment of metastatic melanoma based on positive phase III trials. Both drugs show a clear overall survival benefit, so the timing of when to use ACT will need to be carefully thought out. In contrast to these 2 new, commercially available outpatient treatments, ACT is a personally-specified product and labor-intensive therapy that demands both acquisition of high standard laboratory procedures and close clinical inpatient monitoring during treatment. It is unique among other anti-melanoma treatments, providing the potential for a durable response following a single, self-limited treatment. This perspective drives the efforts to make this protocol accessible for more patients and to explore modifications that may optimize treatment results.

Will T-cell therapy for cancer ever be a standard of care?

Cellular therapies for cancer are showing increasing efficacy but their introduction as a 'standard of care' for these disorders is hampered by technical, regulatory and financial concerns. This review identifies some of the major problems and suggests potential solutions.

Autophagy induced by conventional chemotherapy mediates tumor cell sensitivity to immunotherapy

Autophagy attenuates the efficacy of conventional chemotherapy but its effects on immunotherapy have been little studied. Here, we report that chemotherapy renders tumor cells more susceptible to lysis by CTL in vivo. Moreover, bystander tumor cells that did not express antigen were killed by CTL. This effect was mediated by transient but dramatic upregulation of the mannose-6-phosphate receptor (MPR) on the tumor cell surface. Antitumor effects of combined treatment related to the kinetics of MPR upregulation and abrogation of this event abolished the combined effect of immunotherapy and chemotherapy. MPR accumulation on the tumor cell surface during chemotherapy was observed in different mouse tumor models and in patients with multiple myeloma. Notably, this effect was the result of redistribution of the receptor caused by chemotherapy-inducible autophagy. Together, our findings reveal one molecular mechanism through which the antitumor effects of conventional cancer chemotherapy and immunotherapy are realized.

Adoptive transfer of cytotoxic T lymphocytes targeting two different antigens limits antigen loss and tumor escape

An antitumor T-cell response can lead to tumor control without clearing all tumor cells. As long as residual tumor cells remain, there is a constant risk of escape from that T-cell response. We previously showed that adoptive transfer of anti-ova OT-I T cells into B16ova-bearing mice led to tumor regression followed by escape of tumors that had lost the ova gene, rendering the OT-I T cells ineffective. In this study, we hypothesized that simultaneous transfer of cytotoxic T lymphocytes targeted against two independent antigens would reduce selection for single-antigen-loss cells, thereby limiting tumor escape. Using OT-I and Pmel T cells to treat B16ova tumors, we found that early cotransfer could prevent tumor emergence in most mice, whereas neither T-cell specificity alone was able to do so. When combined with total body irradiation for the treatment of larger 7-day tumors, cotransfer was also better at limiting tumor recurrence, and the tumors that did escape combination therapy continued to express both target antigens. As adoptively transferred T cells also persisted in vivo, even in mice with recurrent tumors, we hypothesized that restimulation of these antitumor T cells would prolong survival of mice with recurrent tumors. Consistent with this hypothesis, administration of a low-dose regimen of cyclophosphamide following tumor escape slowed tumor growth in mice that had previously received T-cell therapy, but not in control-treated mice, an effect that was associated with increased activation of T cells in vitro by low- but not high-dose cyclophosphamide.

Adoptive T-cell therapy using autologous tumor-infiltrating lymphocytes for metastatic melanoma: current status and future outlook

Immunotherapy using autologous T cells has emerged to be a powerful treatment option for patients with metastatic melanoma. These include the adoptive transfer of autologous tumor-infiltrating lymphocytes (TILs), T cells transduced with high-affinity T cell receptors against major tumor antigens, and T cells transduced with chimeric antigen receptors composed of hybrid immunoglobulin light chains with endodomains of T-cell signaling molecules. Among these and other options for T-cell therapy, TILs together with high-dose interleukin 2 have had the longest clinical history with multiple clinical trials in centers across the world consistently demonstrating durable clinical response rates near 50% or more. A distinct advantage of TIL therapy making it still the T-cell therapy of choice is the broad nature of the T-cell recognition against both defined and undefined tumors antigens against all possible major histocompatibility complex, rather than the single specificity and limited major histocompatibility complex coverage of the newer T cell receptors and chimeric antigen receptor transduction technologies. In the past decade, significant inroads have been made in defining the phenotypes of T cells in TIL-mediating tumor regression. CD8+ T cells are emerging to be critical, although the exact subset of CD8+ T cells exhibiting the highest clinical activity in terms of memory and effector markers is still controversial. We present a model in which both effector-memory and more differentiated effector T cells ultimately may need to cooperate to mediate long-term tumor control in responding patients. Although TIL therapy has shown great potential to treat metastatic melanoma, a number of issues have emerged that need to be addressed to bring it more into the mainstream of melanoma care. First, we have a reached the point where a pivotal phase II or phase III trial is needed in an attempt to gain regulatory approval of TILs as standard of care. Second, improvements in how we expand TILs for therapy are needed that minimize the time the T cells are in culture and improve the memory and effector characteristics of the T cells for longer persistence and enhanced anti-tumor activity in vivo. Third, there is a critical need to identify surrogate and predictive biomarkers to better select suitable patients for TIL therapy to improve response rate and duration. Overall, the outlook for TIL therapy for melanoma is very bright. We predict that TILs will indeed emerge to become an approved treatment in the upcoming years through pivotal clinical trials. Moreover, new approaches combining TILs with targeted signaling pathway drugs, such as mutant B-RAF inhibitors, and synergistic immunomodulatory interventions enhancing T-cell costimulation and preventing negative regulation should further increase therapeutic efficacy and durable complete response rates.