Developing innovative strategies of tumor‑infiltrating lymphocyte therapy for tumor treatment

Cancer is the main cause of global mortality, and thus far, effective therapeutic strategies for cancer treatment are in high demand. Adoptive transfer of tumor‑infiltrating lymphocytes (TILs) represents a promising avenue in immunotherapy for the management of malignancies. The clinical safety and efficacy of TIL‑based therapy have been established through numerous rigorous clinical trials. However, the efficacy of TIL infusion in inducing an anti‑tumor response is limited to a subset of clinical patients with cancer. Therefore, there is an urgent need to develop innovative strategies aimed at enhancing the effectiveness of TIL‑based therapy. In the present review, the developmental history of TIL‑based therapy was systematically summarized and analyzed, while also presenting a unique perspective on enhancing the multi‑dimensional anti‑tumor capabilities of TILs. The insight and conclusions presented in this review may contribute to improving the efficacy of TIL‑based therapy and expediting its development.

[An exploratory clinical study of the efficacy and safety of tumor-infiltrating lymphocytes in the treatment of metastatic osteosarcoma]

Objective: To explore the safety and efficacy of tumor-infiltrating lymphocytes (TILs) extracted from tumor tissue in patients with pulmonary metastasis of osteosarcoma, the TILs were amplified in vitro to reach clinical dosage and reinfused to the patients combined with high-dose interleukin 2 (IL-2). Methods: Twelve subjects with pathologically diagnosed osteosarcoma were enrolled from December 2019 to June 20, 2021 in Shanghai General Hospital. All subjects progressed with metastasis after standard chemotherapy and failed multiple lines of treatments. Fresh tumor tissue was obtained from the metastatic site and extracted and amplified by Good Manufacturing Practice (GMP) workshop to produce TILs to clinical treatment dosage (10⁹-10¹¹). High-dose IL-2 (100 000-200 000 U/kg) was administered immediately after autogenous TILs infusion to promote the activation, proliferation and antitumor cytolytic activity in vivo. Adverse events (AE) were graded according to Common Terminology Criteria for Adverse Events (CTCAE) standard and tumor response was assessed according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Results: One patient did not receive treatment due to failure in isolating TILs, total of 11 patients received a single re-infusion of autologous TILs. There were 10 males and 1 female with a median age of 19.9 years (12-33 years). Six of these patients received higher dose levels of 1.0×10¹⁰ TILs. The 11 patients were followed-up for 1 to 13 months and tolerated well. The most common adverse events reported were fever (10/11), constipation (3/11) and elevated gamma-glutamyl transferase (GGT) (3/11). The high incidence of fever was due to the IL-2 infusion. All patients experienced a transient drop in lymphocyte count and leukopenia leading to non-myeloid ablative lymphocyte clearance. The AE included grade 4 hematologic toxicity, including 8 cases of lymphocytopenia, 2 cases of neutropenia and 1 case of thrombocytopenia. No AE of neurotoxicity occurred. Of all the 11 patients, 9 patients got stable disease (SD) and 2 patients had progressive disease (PD). The disease control rate was 9/11. The median duration of SD was more than 4 months, and the maximum tumor volume decreased by close to 20%. Patient number 9 had sustained SD status for more than 6 months. Conclusions: TILs with in vitro expansion ability could be isolated from tumor tissues of advanced osteosarcoma patients. TILs amplified and reinfused in vitro have anti-osteosarcoma activity.

Targeting regulator of G protein signaling 1 in tumor-specific T cells enhances their trafficking to breast cancer

Reduced infiltration of anti-tumor lymphocytes remains a major cause of tumor immune evasion and is correlated with poor cancer survival. Here, we found that upregulation of regulator of G protein signaling (RGS)1 in helper TH1 cells and cytotoxic T lymphocytes (CTLs) reduced their trafficking to and survival in tumors and was associated with shorter survival of patients with breast and lung cancer. RGS1 was upregulated by type II interferon (IFN)-signal transducer and activator of transcription (STAT)1 signaling and impaired trafficking of circulating T cells to tumors by inhibiting calcium influx and suppressing activation of the kinases ERK and AKT. RGS1 knockdown in adoptively transferred tumor-specific CTLs significantly increased their infiltration and survival in breast and lung tumor grafts and effectively inhibited tumor growth in vivo, which was further improved when combined with programmed death ligand (PD-L)1 checkpoint inhibition. Our findings reveal RGS1 is important for tumor immune evasion and suggest that targeting RGS1 may provide a new strategy for tumor immunotherapy.

Bifunctional iRGD-anti-CD3 enhances antitumor potency of T cells by facilitating tumor infiltration and T-cell activation

BACKGROUND

Poor infiltration and limited activation of transferred T cells are fundamental factors impeding the development of adoptive cell immunotherapy in solid tumors. A tumor-penetrating peptide iRGD has been widely used to deliver drugs deep into tumor tissues. CD3-targeting bispecific antibodies represent a promising immunotherapy which recruits and activates T cells.

METHODS

T-cell penetration was demonstrated in tumor spheroids using confocal microscope, and in xenografted tumors by histology and in vivo real-time fluorescence imaging. Activation and cytotoxicity of T cells were assessed by flow cytometry and confocal microscope. Bioluminescence imaging was used to evaluate in vivo antitumor effects, and transmission electron microscopy was used for mechanistic studies.

RESULTS

We generated a novel bifunctional agent iRGD-anti-CD3 which could immobilize iRGD on the surface of T cells through CD3 engaging. We found that iRGD-anti-CD3 modification not only facilitated T-cell infiltration in 3D tumor spheroids and xenografted tumor nodules but also induced T-cell activation and cytotoxicity against target cancer cells. T cells modified with iRGD-anti-CD3 significantly inhibited tumor growth and prolonged survival in several xenograft mouse models, which was further enhanced by the combination of programmed cell death protein 1 (PD-1) blockade. Mechanistic studies revealed that iRGD-anti-CD3 initiated a transport pathway called vesiculovacuolar organelles in the endothelial cytoplasm to promote T-cell extravasation.

CONCLUSION

Altogether, we show that iRGD-anti-CD3 modification is an innovative and bifunctional strategy to overcome major bottlenecks in adoptive cell therapy. Moreover, we demonstrate that combination with PD-1 blockade can further improve antitumor efficacy of iRGD-anti-CD3-modified T cells.

Potent ex vivo armed T cells using recombinant bispecific antibodies for adoptive immunotherapy with reduced cytokine release

BACKGROUND

T cell-based immunotherapies using chimeric antigen receptors (CAR) or bispecific antibodies (BsAb) have produced impressive responses in hematological malignancies. However, major hurdles remained, including cytokine release syndrome, neurotoxicity, on-target off-tumor effects, reliance on autologous T cells, and failure in most solid tumors. BsAb armed T cells offer a safe alternative.

METHODS

We generated ex vivo armed T cells (EATs) using IgG-[L]-scFv-platformed BsAb, where the anti-CD3 (huOKT3) scFv was attached to the light chain of a tumor-binding IgG. BsAb density on EAT, in vitro cytotoxicity, cytokine release, in vivo trafficking into tumors, and their antitumor activities were evaluated in multiple cancer cell lines and patient-derived xenograft mouse models. The efficacy of EATs after cryopreservation was studied, and gamma delta (γδ) T cells were investigated as unrelated alternative effector T cells.

RESULTS

The antitumor potency of BsAb armed T cells was substantially improved using the IgG-[L]-scFv BsAb platform. When compared with separate BsAb and T cell injection, EATs released less TNF-α, and infiltrated tumors faster, while achieving robust antitumor responses. The in vivo potency of EAT therapy depended on BsAb dose for arming, EAT cell number per injection, total number of EAT doses, and treatment schedule intensity. The antitumor efficacy of EATs was preserved following cryopreservation, and EATs using γδ T cells were safe and as effective as αβ T cell-EATs.

CONCLUSIONS

EATs exerted potent antitumor activities against a broad spectrum of human cancer targets with remarkable safety. The antitumor potency of EATs depended on BsAb dose, cell number and total dose, and schedule. EATs were equally effective after cryopreservation, and the feasibility of third-party γδ-EATs offered an alternative for autologous T cell sources.

Distinct metabolic programs established in the thymus control effector functions of γδ T cell subsets in tumor microenvironments

Metabolic programming controls immune cell lineages and functions, but little is known about γδ T cell metabolism. Here, we found that γδ T cell subsets making either interferon-γ (IFN-γ) or interleukin (IL)-17 have intrinsically distinct metabolic requirements. Whereas IFN-γ+ γδ T cells were almost exclusively dependent on glycolysis, IL-17+ γδ T cells strongly engaged oxidative metabolism, with increased mitochondrial mass and activity. These distinct metabolic signatures were surprisingly imprinted early during thymic development and were stably maintained in the periphery and within tumors. Moreover, pro-tumoral IL-17+ γδ T cells selectively showed high lipid uptake and intracellular lipid storage and were expanded in obesity and in tumors of obese mice. Conversely, glucose supplementation enhanced the antitumor functions of IFN-γ+ γδ T cells and reduced tumor growth upon adoptive transfer. These findings have important implications for the differentiation of effector γδ T cells and their manipulation in cancer immunotherapy.

NF-κB-inducing kinase maintains T cell metabolic fitness in antitumor immunity

Metabolic reprograming toward aerobic glycolysis is a pivotal mechanism shaping immune responses. Here we show that deficiency in NF-κB-inducing kinase (NIK) impairs glycolysis induction, rendering CD8+ effector T cells hypofunctional in the tumor microenvironment. Conversely, ectopic expression of NIK promotes CD8+ T cell metabolism and effector function, thereby profoundly enhancing antitumor immunity and improving the efficacy of T cell adoptive therapy. NIK regulates T cell metabolism via a NF-κB-independent mechanism that involves stabilization of hexokinase 2 (HK2), a rate-limiting enzyme of the glycolytic pathway. NIK prevents autophagic degradation of HK2 through controlling cellular reactive oxygen species levels, which in turn involves modulation of glucose-6-phosphate dehydrogenase (G6PD), an enzyme that mediates production of the antioxidant NADPH. We show that the G6PD-NADPH redox system is important for HK2 stability and metabolism in activated T cells. These findings establish NIK as a pivotal regulator of T cell metabolism and highlight a post-translational mechanism of metabolic regulation.

Promising Immuno-Oncology Options for the Future: Cellular Therapies and Personalized Cancer Vaccines

A common pathway for an effective immune anticancer response involves recognition of tumor neoantigens and subsequent targeting of cancer cells by T cells. In this article, we provide an overview of the current status of two approaches to directly enhance this interaction using either adoptive cell therapy or personalized cancer vaccines with focus on recent advances in solid tumors, including lung cancer.

Efficacy of adoptive therapy with tumor-infiltrating lymphocytes and recombinant interleukin-2 in advanced cutaneous melanoma: a systematic review and meta-analysis

Adoptive cell therapy (ACT) using autologous tumor-infiltrating lymphocytes (TIL) has been tested in advanced melanoma patients at various centers. We conducted a systematic review and meta-analysis to assess its efficacy on previously treated advanced metastatic cutaneous melanoma. The PubMed electronic database was searched from inception to 17 December 2018 to identify studies administering TIL-ACT and recombinant interleukin-2 (IL-2) following non-myeloablative chemotherapy in previously treated metastatic melanoma patients. Objective response rate (ORR) was the primary end point. Secondary end points were complete response rate (CRR), overall survival (OS), duration of response (DOR) and toxicity. Pooled estimates were derived from fixed or random effect models, depending on the amount of heterogeneity detected. Analysis was carried out separately for high dose (HD) and low dose (LD) IL-2. Sensitivity analyses were carried out. Among 1211 records screened, 13 studies (published 1988 - 2016) were eligible for meta-analysis. Among 410 heavily pretreated patients (some with brain metastasis), 332 received HD-IL-2 and 78 LD-IL-2. The pooled overall ORR estimate was 41% [95% confidence interval (CI) 35% to 48%], and the overall CRR was 12% (95% CI 7% to 16%). For the HD-IL-2 group, the ORR was 43% (95% CI 36% to 50%), while for the LD-IL-2 it was 35% (95% CI 25% to 45%). Corresponding pooled estimates for CRR were 14% (95% CI 7% to 20%) and 7% (95% CI 1% to 12%). The majority of HD-IL-2 complete responders (27/28) remained in remission during the extent of follow-up after CR (median 40 months). Sensitivity analyses yielded similar results. Higher number of infused cells was associated with a favorable response. The ORR for HD-IL-2 compared favorably with the nivolumab/ipilimumab combination following anti-PD-1 failure. TIL-ACT therapy, especially when combined with HD-IL-2, achieves durable clinical benefit and warrants further investigation. We discuss the current position of TIL-ACT in the therapy of advanced melanoma, particularly in the era of immune checkpoint blockade therapy, and review future opportunities for improvement of this approach.

Single-Cell Transcriptome Analysis Reveals Gene Signatures Associated with T-cell Persistence Following Adoptive Cell Therapy

Adoptive cell therapy (ACT) using tumor-infiltrating lymphocytes (TIL) can mediate responses in some patients with metastatic epithelial cancer. Identifying gene signatures associated with successful ACT might enable the development of improved therapeutic approaches. The persistence of transferred T cells in the peripheral blood is one indication of clinical effectiveness, but many T-cell and host factors may influence T-cell persistence. To limit these variables, we previously studied a patient with metastatic colorectal cancer treated with polyclonal TILs targeting the KRAS(G12D) hotspot mutation, who experienced a partial response for 9 months. Three dominant clonotypes specifically recognizing KRAS(G12D) epitopes were identified, but we found that only two clonotypes persisted 40 days after ACT. Because of these findings, in this study, we performed the single-cell transcriptome analysis of the infused TILs. The analysis revealed a total of 472 genes that were differentially expressed between clonotypes 9.1-NP and 9.2-P single cells, and 528 genes between 9.1-NP and 10-P. Following these clonotypes in the peripheral blood after ACT, the gene expression patterns changed, but IL7R, ITGB1, KLF2, and ZNF683 remained expressed in the persistent 9.2-P and 10-P cells, compared with the nonpersistent 9.1-NP cells. In addition, four autologous TILs, which were used for treatment but persisted poorly 1 month after ACT, did not express the gene profiles associated with persistence. These results suggest that certain TIL populations possess a unique gene expression profile that can lead to the persistence of T cells. Thus, this single-patient study provides insight into how to improve ACT for solid cancer.

Treatment With Tumor-infiltrating Lymphocytes in Advanced Melanoma: Evaluation of Early Clinical Implementation of an Advanced Therapy Medicinal Product

Tumor-infiltrating lymphocytes (TIL)-therapy in advanced melanoma is an advanced therapy medicinal product (ATMP) which, despite promising results, has not been implemented widely. In a European setting, TIL-therapy has been in use since 2011 and is currently being evaluated in a randomized controlled trial. As clinical implementation of ATMPs is challenging, this study aims to evaluate early application of TIL-therapy, through the application of a constructive technology assessment (CTA). First the literature on ATMP barriers and facilitators in clinical translation was summarized. Subsequently, application of TIL-therapy was evaluated through semistructured interviews with 26 stakeholders according to 6 CTA domains: clinical, economic, patient-related, organizational, technical, and future. In addition, treatment costs were estimated. A number of barriers to clinical translation were identified in the literature, including: inadequate financial support, lack of regulatory knowledge, risks in using live tissues, and the complex path to market approval. Innovative reimbursement procedures could particularly facilitate translation. The CTA survey of TIL-therapy acknowledged these barriers, and revealed the following facilitators: the expected effectiveness resulting in institutional support for an internal pilot, the results of which led to the inclusion of TIL-therapy in a national coverage with evidence development program, the availability of an in-house pharmacist, quality assurance expertise and a TIL-skilled technician. Institutional and national implementation of TIL-therapy remains complex. The promising clinical effectiveness is expected to facilitate the adoption of TIL-therapy, especially when validated through a randomized controlled trial. Innovative and conditional reimbursement procedures, together with the organization of knowledge transfer, could support and improve clinical translation of TIL and ATMPs.

Phase II clinical trial of adoptive cell therapy for patients with metastatic melanoma with autologous tumor-infiltrating lymphocytes and low-dose interleukin-2

Adoptive cell therapy using autologous tumor-infiltrating lymphocytes (TIL) has shown significant clinical benefit, but is limited by toxicities due to a requirement for post-infusion interleukin-2 (IL-2), for which high dose is standard. To assess a modified TIL protocol using lower dose IL-2, we performed a single institution phase II protocol in unresectable, metastatic melanoma. The primary endpoint was response rate. Secondary endpoints were safety and assessment of immune correlates following TIL infusion. Twelve metastatic melanoma patients were treated with non-myeloablative lymphodepleting chemotherapy, TIL, and low-dose subcutaneous IL-2 (125,000 IU/kg/day, maximum 9-10 doses over 2 weeks). All but one patient had previously progressed after treatment with immune checkpoint inhibitors. No unexpected adverse events were observed, and patients received an average of 6.8 doses of IL-2. By RECIST v1.1, two patients experienced a partial response, one patient had an unconfirmed partial response, and six had stable disease. Biomarker assessment confirmed an increase in IL-15 levels following lymphodepleting chemotherapy as expected and a lack of peripheral regulatory T-cell expansion following protocol treatment. Interrogation of the TIL infusion product and monitoring of the peripheral blood following infusion suggested engraftment of TIL. In one responding patient, a population of T cells expressing a T-cell receptor Vβ chain that was dominant in the infusion product was present at a high percentage in peripheral blood more than 2 years after TIL infusion. This study shows that this protocol of low-dose IL-2 following adoptive cell transfer of TIL is feasible and clinically active. (ClinicalTrials.gov identifier NCT01883323.).

HER2 CAR-T Cells Eradicate Uveal Melanoma and T-cell Therapy-Resistant Human Melanoma in IL2 Transgenic NOD/SCID IL2 Receptor Knockout Mice

Chimeric antigen receptors (CAR) can transmit signals akin to those from activated T-cell receptors when bound to a cell surface target. CAR-expressing T cells against CD19 can cause curative effects in leukemia and lymphoma and is approved for clinical use. However, no CAR-T therapy is currently approved for use in solid tumors. We hypothesize that the resistance of solid tumors to CAR-T can be overcome by similar means as those used to reactivate tumor-infiltrating T lymphocytes (TIL), for example, by cytokines or immune checkpoint blockade. Here we demonstrate that CAR-T cells directed against HER2 can kill uveal and cutaneous melanoma cells in vitro and in vivo. Curative effects in vivo were only observed in xenografts grown in a NOD/SCID IL2 receptor gamma (NOG) knockout mouse strain transgenic for human IL2. The effect was target-specific, as CRISPR/Cas9-mediated disruption of HER2 in the melanoma cells abrogated the killing effect of the CAR-T cells. The CAR-T cells were also able to kill melanoma cells from patients resistant to adoptive T-cell transfer (ACT) of autologous TILs. Thus, CAR-T therapy represents an option for patients that do not respond to immunotherapy with ACT of TIL or immune checkpoint blockade. In addition, our data highlight the use of IL2 transgenic NOG mice as models to prove efficacy of CAR-T-cell products, possibly even in a personalized manner. SIGNIFICANCE: These findings demonstrate that a novel humanized mouse model can help clinical translation of CAR-T cells against uveal and cutaneous melanoma that do not respond to TIL therapy or immune checkpoint blockade.

Outcomes of Adoptive Cell Transfer With Tumor-infiltrating Lymphocytes for Metastatic Melanoma Patients With and Without Brain Metastases

Brain metastases cause significant morbidity and mortality in patients with metastatic melanoma. Although adoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TIL) can achieve complete and durable remission of advanced cutaneous melanoma, the efficacy of this therapy for brain metastases is unclear. Records of patients with M1c melanoma treated with ACT using TIL, including patients with treated and untreated brain metastases, were analyzed. Treatment consisted of preparative chemotherapy, autologous TIL infusion, and high-dose interleukin-2. Treatment outcomes, sites of initial tumor progression, and overall survival were analyzed. Among 144 total patients, 15 patients with treated and 18 patients with untreated brain metastases were identified. Intracranial objective responses (OR) occurred in 28% patients with untreated brain metastases. The systemic OR rates for patients with M1c disease without identified brain disease, treated brain disease, and untreated brain disease, and were 49%, 33% and 33%, respectively, of which 59%, 20% and 16% were durable at last follow-up. The site of untreated brain disease was the most likely site of initial tumor progression (61%) in patients with untreated brain metastases. Overall, we found that ACT with TIL can eliminate small melanoma brain metastases. However, following TIL therapy these patients frequently progress in the brain at a site of untreated brain disease. Patients with treated or untreated brain disease are less likely to achieve durable systemic ORs following TIL therapy compared with M1c disease and no history of brain disease. Melanoma brain metastases likely require local therapy despite the systemic effect of ACT.

4-1BB Agonist Focuses CD8+ Tumor-Infiltrating T-Cell Growth into a Distinct Repertoire Capable of Tumor Recognition in Pancreatic Cancer

Purpose: Survival for pancreatic ductal adenocarcinoma (PDAC) patients is extremely poor and improved therapies are urgently needed. Tumor-infiltrating lymphocyte (TIL) adoptive cell therapy (ACT) has shown great promise in other tumor types, such as metastatic melanoma where overall response rates of 50% have been seen. Given this success and the evidence showing that T-cell presence positively correlates with overall survival in PDAC, we sought to enrich for CD8+ TILs capable of autologous tumor recognition. In addition, we explored the phenotype and T-cell receptor repertoire of the CD8+ TILs in the tumor microenvironment.Experimental Design: We used an agonistic 4-1BB mAb during the initial tumor fragment culture to provide 4-1BB costimulation and assessed changes in TIL growth, phenotype, repertoire, and antitumor function.Results: Increased CD8+ TIL growth from PDAC tumors was achieved with the aid of an agonistic 4-1BB mAb. Expanded TILs were characterized by an activated but not terminally differentiated phenotype. Moreover, 4-1BB stimulation expanded a more clonal and distinct CD8+ TIL repertoire than IL2 alone. TILs from both culture conditions displayed MHC class I-restricted recognition of autologous tumor targets.Conclusions: Costimulation with an anti-4-1BB mAb increases the feasibility of TIL therapy by producing greater numbers of these tumor-reactive T cells. These results suggest that TIL ACT for PDAC is a potential treatment avenue worth further investigation for a patient population in dire need of improved therapy. Clin Cancer Res; 23(23); 7263-75. ©2017 AACR.

Future perspectives in melanoma research "Melanoma Bridge", Napoli, November 30th-3rd December 2016

Major advances have been made in the treatment of cancer with targeted therapy and immunotherapy; several FDA-approved agents with associated improvement of 1-year survival rates became available for stage IV melanoma patients. Before 2010, the 1-year survival were quite low, at 30%; in 2011, the rise to nearly 50% in the setting of treatment with Ipilimumab, and rise to 70% with BRAF inhibitor monotherapy in 2013 was observed. Even more impressive are 1-year survival rates considering combination strategies with both targeted therapy and immunotherapy, now exceeding 80%. Can we improve response rates even further, and bring these therapies to more patients? In fact, despite these advances, responses are heterogeneous and are not always durable. There is a critical need to better understand who will benefit from therapy, as well as proper timing, sequence and combination of different therapeutic agents. How can we better understand responses to therapy and optimize treatment regimens? The key to better understanding therapy and to optimizing responses is with insights gained from responses to targeted therapy and immunotherapy through translational research in human samples. Combination therapies including chemotherapy, radiotherapy, targeted therapy, electrochemotherapy with immunotherapy agents such as Immune Checkpoint Blockers are under investigation but there is much room for improvement. Adoptive T cell therapy including tumor infiltrating lymphocytes and chimeric antigen receptor modified T cells therapy is also efficacious in metastatic melanoma and outcome enhancement seem likely by improved homing capacity of chemokine receptor transduced T cells. Tumor infiltrating lymphocytes therapy is also efficacious in metastatic melanoma and outcome enhancement seem likely by improved homing capacity of chemokine receptor transduced T cells. Understanding the mechanisms behind the development of acquired resistance and tests for biomarkers for treatment decisions are also under study and will offer new opportunities for more efficient combination therapies. Knowledge of immunologic features of the tumor microenvironment associated with response and resistance will improve the identification of patients who will derive the most benefit from monotherapy and might reveal additional immunologic determinants that could be targeted in combination with checkpoint blockade. The future of advanced melanoma needs to involve education and trials, biobanks with a focus on primary tumors, bioinformatics and empowerment of patients and clinicians.

Treatment of metastatic uveal melanoma with adoptive transfer of tumour-infiltrating lymphocytes: a single-centre, two-stage, single-arm, phase 2 study

BACKGROUND

Uveal melanoma is a rare tumour with no established treatments once metastases develop. Although a variety of immune-based therapies have shown efficacy in metastatic cutaneous melanoma, their use in ocular variants has been disappointing. Recently, adoptive T-cell therapy has shown salvage responses in multiple refractory solid tumours. Thus, we sought to determine if adoptive transfer of autologous tumour-infiltrating lymphocytes (TILs) could mediate regression of metastatic uveal melanoma.

METHODS

In this ongoing single-centre, two-stage, phase 2, single-arm trial, patients (aged ≥16 years) with histologically confirmed metastatic ocular melanoma were enrolled. Key eligibility criteria were an Eastern Cooperative Oncology Group performance status of 0 or 1, progressive metastatic disease, and adequate haematological, renal, and hepatic function. Metastasectomies were done to procure tumour tissue to generate autologous TIL cultures, which then underwent large scale ex-vivo expansion. Patients were treated with lymphodepleting conditioning chemotherapy (intravenous cyclophosphamide [60 mg/kg] daily for 2 days followed by fludarabine [25 mg/m2] daily for 5 days, followed by a single intravenous infusion of autologous TILs and high-dose interleukin-2 [720 000 IU/kg] every 8 h). The primary endpoint was objective tumour response in evaluable patients per protocol using Response to Evaluation Criteria in Solid Tumors, version 1.0. An interim analysis of this trial is reported here. The trial is registered at ClinicalTrials.gov, number NCT01814046.

FINDINGS

From the completed first stage and ongoing expansion stage of this trial, a total of 21 consecutive patients with metastatic uveal melanoma were enrolled between June 7, 2013, and Sept 9, 2016, and received TIL therapy. Seven (35%, 95% CI 16-59) of 20 evaluable patients had objective tumour regression. Among the responders, six patients achieved a partial response, two of which are ongoing and have not reached maximum response. One patient achieved complete response of numerous hepatic metastases, currently ongoing at 21 months post therapy. Three of the responders were refractory to previous immune checkpoint blockade. Common grade 3 or worse toxic effects were related to the lymphodepleting chemotherapy regimen and included lymphopenia, neutropenia, and thrombocytopenia (21 [100%] patients for each toxicity); anaemia (14 [67%] patients); and infection (six [29%] patients). There was one treatment-related death secondary to sepsis-induced multiorgan failure.

INTERPRETATION

To our knowledge, this is the first report describing adoptive transfer of autologous TILs to mediate objective tumour regression in patients with metastatic uveal melanoma. These initial results challenge the belief that metastatic uveal melanoma is immunotherapy resistant and support the further investigation of immune-based therapies for this cancer. Refinement of this T-cell therapy is crucial to improve the frequency of clinical responses and the general applicability of this treatment modality.

FUNDING

Intramural Research Program of the National Institutes of Health, National Cancer Institute, Center for Cancer Research.

Increasing the safety and efficacy of chimeric antigen receptor T cell therapy

Chimeric antigen receptor (CAR) T cell therapy is a promising cancer treatment that has recently been undergoing rapid development. However, there are still some major challenges, including precise tumor targeting to avoid off-target or “on-target/off-tumor” toxicity, adequate T cell infiltration and migration to solid tumors and T cell proliferation and persistence across the physical and biochemical barriers of solid tumors. In this review, we focus on the primary challenges and strategies to design safe and effective CAR T cells, including using novel cutting-edge technologies for CAR and vector designs to increase both the safety and efficacy, further T cell modification to overcome the tumor-associated immune suppression, and using gene editing technologies to generate universal CAR T cells. All these efforts promote the development and evolution of CAR T cell therapy and move toward our ultimate goal—curing cancer with high safety, high efficacy, and low cost.

Importance of CD200 expression by tumor or host cells to regulation of immunotherapy in a mouse breast cancer model

Cell-surface CD200 expression by mouse EMT6 breast tumor cells increased primary tumor growth and metastasis to the draining lymph nodes (DLN) in normal (WT) BALB/c female recipients, while lack of CD200R1 expression in a CD200R1^-/- host negated this effect. Silencing CD200 expression in EMT6^siCD200 tumor cells also reduced their ability to grow and metastasize in WT animals. The cellular mechanisms responsible for these effects have not been studied in detail. We report characterization of tumor infiltrating (TILs) and draining lymph node (DLN) cells in WT and CD200^-/- BALB/c mice, receiving WT tumor cells, or EMT6 lacking CD200 expression (EMT6^siCD200 cells). Our data show an important correlation with augmented CD8⁺ cytotoxic T cells and resistance to tumor growth in mice lacking exposure (on either host cells or tumor) to the immunoregulatory molecule CD200. Confirmation of the importance of such CD8⁺ cells came from monitoring tumor growth and characterization of the TILs and DLN cells in WT mice challenged with EMT6 and EMT6^siCD200 tumors and treated with CD8 and CD4 depleting antibodies. Finally, we have assessed the mechanisms(s) whereby addition of metformin as an augmenting chemotherapeutic agent in CD200^-/- animals given EMT6 tumors and treated with a previously established immunotherapy regime can increase host resistance. Our data support the hypothesis that increased autophagy in the presence of metformin increases CD8⁺ responses and tumor resistance, an effect attenuated by the autophagy inhibitor verteporfin.

Prospects for chimeric antigen receptor (CAR) γδ T cells: A potential game changer for adoptive T cell cancer immunotherapy

Excitement is growing for therapies that harness the power of patients' immune systems to combat their diseases. One approach to immunotherapy involves engineering patients' own T cells to express a chimeric antigen receptor (CAR) to treat advanced cancers, particularly those refractory to conventional therapeutic agents. Although these engineered immune cells have made remarkable strides in the treatment of patients with certain hematologic malignancies, success with solid tumors has been limited, probably due to immunosuppressive mechanisms in the tumor niche. In nearly all studies to date, T cells bearing αβ receptors have been used to generate CAR T cells. In this review, we highlight biological characteristics of γδ T cells that are distinct from those of αβ T cells, including homing to epithelial and mucosal tissues and unique functions such as direct antigen recognition, lack of alloreactivity, and ability to present antigens. We offer our perspective that these features make γδ T cells promising for use in cellular therapy against several types of solid tumors, including melanoma and gastrointestinal cancers. Engineered γδ T cells should be considered as a new platform for adoptive T cell cancer therapy for mucosal tumors.

Anti-CD137 monoclonal antibodies and adoptive T cell therapy: a perfect marriage?

CD137(4-1BB) costimulation and adoptive T cell therapy strongly synergize in terms of achieving maximal efficacy against experimental cancers. These costimulatory biological functions of CD137 have been exploited by means of introducing the CD137 signaling domain in clinically successful chimeric antigen receptors and to more efficiently expand T cells in culture. In addition, immunomagnetic sorting of CD137-positive T cells among tumor-infiltrating lymphocytes selects for the fittest antitumor T lymphocytes for subsequent cultures. In mouse models, co-infusion of both agonist antibodies and T cells attains marked synergistic effects that result from more focused and intense cytolytic activity visualized under in vivo microscopy and from more efficient entrance of T cells into the tumor through the vasculature. These several levels of dynamic interaction between adoptive T cell therapy and CD137 offer much opportunity to raise the efficacy of current cancer immunotherapies.

Adoptive T cell therapy combined with intralesional administrations of TG1042 (adenovirus expressing interferon-γ) in metastatic melanoma patients

Tumor immune escape has recently been shown to be related to the development of an immune tolerance state of the microenvironment. Cytokines activating the immune system such as IFN-γ can be used to reverse the immune escape and thus to potentiate the efficacy of immunotherapy. A clinical study was conducted in 18 stage IIIc/IV melanoma patients treated with tumor-infiltrating lymphocytes (TILs) in combination with intratumoral TG1042 injection (adenovirus expressing IFN-γ). The primary objective was to investigate the safety of treatment. Secondary objectives were to study the clinical response and translational research. The treatment was well tolerated. Among the 13 patients evaluable for tumor response, 38.5% had an overall objective response (OOR = CR + PR) and disease control rate (DCR = CR + PR + S) of 46%. The clinical response of the 37 targeted lesions led to an OOR of 51% and a DCR of 75%. Translational research on predictive markers did not significantly differ between responder and non-responder patients. However, specifically regarding injected lesions, the clinical response correlated with CD3-/CD56+ NK cells which could be activated by TG1042. Further larger studies of this combined immunotherapy are needed to confirm our findings. Intralesional TG1042 combined with antigen-selected TILs should be discussed.

Marrow-Infiltrating Lymphocytes Are Effective in Multiple Myeloma

Adoptive transfer of activated marrow-infiltrating lymphocytes (MIL) induces anti-myeloma immunity.

A phase I clinical trial combining dendritic cell vaccination with adoptive T cell transfer in patients with stage IV melanoma

Adoptive transfer of in vitro-expanded tumor-infiltrating lymphocytes (TIL) has shown great clinical benefit in patients with malignant melanoma. TIL therapy itself has little side effects, but conditioning chemo- or radiotherapy and postinfusion interleukin 2 (IL-2) injections are associated with severe adverse advents. We reasoned that combining TIL infusion with dendritic cell (DC) vaccination could circumvent the need for conditioning and IL-2 support and thus represent a milder treatment approach. Eight patients with stage IV melanoma were enrolled in the MAT01 study, consisting of vaccination with autologous tumor-lysate-loaded DC, followed by TIL infusion. Six of eight patients were treated according to protocol, while one patient received only TIL and one only DC. Treatments were well tolerated with a single grade 3 adverse event. The small study size precludes analysis of clinical responses, though interestingly one patient showed a complete remission and two had stable disease. Analysis of the infusion products revealed that mature DC were generated in all cases. TIL after expansion were CD3+ T cells, dominated by effector memory CD8+ cytotoxic T cells. Analysis of the T cell receptor repertoire revealed presence of highly dominant clones in most infusion products, and many of these could be detected in the circulation for weeks after T cell transfer. Here, we report the first combination of DC vaccination and TIL infusion in malignant melanoma. This combined treatment was safe and feasible, though after evaluating both clinical and immunological parameters, we expect that administration of lymphodepleting chemotherapy and IL-2 will likely increase treatment efficacy.

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.

Cancer immunotherapy based on mutation-specific CD4+ T cells in a patient with epithelial cancer

Limited evidence exists that humans mount a mutation-specific T cell response to epithelial cancers. We used a whole-exomic-sequencing-based approach to demonstrate that tumor-infiltrating lymphocytes (TIL) from a patient with metastatic cholangiocarcinoma contained CD4+ T helper 1 (T(H)1) cells recognizing a mutation in erbb2 interacting protein (ERBB2IP) expressed by the cancer. After adoptive transfer of TIL containing about 25% mutation-specific polyfunctional T(H)1 cells, the patient achieved a decrease in target lesions with prolonged stabilization of disease. Upon disease progression, the patient was retreated with a >95% pure population of mutation-reactive T(H)1 cells and again experienced tumor regression. These results provide evidence that a CD4+ T cell response against a mutated antigen can be harnessed to mediate regression of a metastatic epithelial cancer.

[Melanoma: Cellular and vaccinal immunotherapy]

Melanoma is a malignancy in which the immune system plays a central role, thus explaining the effectiveness of therapeutic vaccination and cellular immunotherapy with tumor-infiltrating lymphocytes. The identification of specific melanoma antigens was an important step in the development of these new approaches. These treatments are capable of yielding tumor responses that last several years, but the response rate is currently inadequate. The crucial role of the tumor microenvironment has recently been shown: melanoma cells render their immediate environment immunotolerant, undermining the effectiveness of stimulated cytotoxic T lymphocytes. The mechanisms responsible for this state of immune tolerance are a major focus of research. Current therapeutic strategies are based on early adjuvant approaches, destruction of regulatory T cells by lymphodepletion prior to immunotherapy, selection of the melanoma antigens inducing the best cytotoxic T cell responses, and combining cellular therapy with monoclonal antibodies that block molecules inhibiting T lymphocyte activation. Immune therapy for melanoma is thus moving towards adjuvant strategies for early-stage disease and combined treatments for metastatic melanoma. It is also important to identify markers that can be used to predict which patients will respond to a given treatment.

Co-stimulation through 4-1BB/CD137 improves the expansion and function of CD8(+) melanoma tumor-infiltrating lymphocytes for adoptive T-cell therapy

Adoptive T-cell therapy (ACT) using tumor-infiltrating lymphocytes (TIL) can induce tumor regression in up to 50% or more of patients with unresectable metastatic melanoma. However, current methods to expand melanoma TIL, especially the “rapid expansion protocol” (REP) were not designed to enhance the generation of optimal effector-memory CD8⁺ T cells for infusion. One approach to this problem is to manipulate specific co-stimulatory signaling pathways to enhance CD8⁺ effector-memory T-cell expansion. In this study, we determined the effects of activating the TNF-R family member 4-1BB/CD137, specifically induced in activated CD8⁺ T cells, on the yield, phenotype, and functional activity of expanded CD8⁺ T cells during the REP. We found that CD8⁺ TIL up-regulate 4-1BB expression early during the REP after initial TCR stimulation, but neither the PBMC feeder cells in the REP or the activated TIL expressed 4-1BB ligand. However, addition of an exogenous agonistic anti-4-1BB IgG₄ (BMS 663513) to the REP significantly enhanced the frequency and total yield of CD8⁺ T cells as well as their maintenance of CD28 and increased their anti-tumor CTL activity. Gene expression analysis found an increase in bcl-2 and survivin expression induced by 4-1BB that was associated with an enhanced survival capability of CD8⁺ post-REP TIL when re-cultured in the absence or presence of cytokines. Our findings suggest that adding an agonistic anti-4-1BB antibody during the time of TIL REP initiation produces a CD8⁺ T cell population capable of improved effector function and survival. This may greatly improve TIL persistence and anti-tumor activity in vivo after adoptive transfer into patients.

Shifting the equilibrium in cancer immunoediting: from tumor tolerance to eradication

The continual interaction of the immune system with a developing tumor is thought to result in the establishment of a dynamic state of equilibrium. This equilibrium depends on the balance between effector and regulatory T-cell compartments. Whereas regulatory T cells can infiltrate and accumulate within tumors, effector T cells fail to efficiently do so. Furthermore, effector T cells that do infiltrate the tumor become tightly controlled by different regulatory cellular subsets and inhibitory molecules. The outcome of this balance is critical to survival, and whereas in some cases the equilibrium can rapidly result in the elimination of the transformed cells by the immune system, in many other cases the tumor manages to escape immune control. In this review, we discuss relevant work focusing on the establishment of the intratumor balance, the dynamic changes in the populations of effector and regulatory T cells within the tumor, and the role of the tumor vasculature and its activation state in the recruitment of different T-cell subsets. Finally, we also discuss work associated to the manipulation of the immune response to tumors and its impact on the infiltration, accumulation, and function of tumor-reactive lymphocytes within the tumor microenvironment.

Immunotherapy for metastatic solid cancers

After decades of research on solid tumor immunology, immunotherapy has shown effectiveness in patients with metastatic solid cancers. Immune modulators such as IL-2 and anti-CTLA-4 can mediate tumor regression in patients with metastatic melanoma and renal cancer, two tumor types that appear exceptional in their ability to spontaneously harbor endogenous antitumor immune cells. The responses can be long lasting, but the number of patients who benefit from these molecules remains limited. Combinations of these agents with cytotoxic and biologic agents are being investigated as a means to increase response rates and in an attempt to broaden application to other cancer types. Rare responses to cancer vaccines suggest that a better understanding of the underlying biology and mechanism of actions may lead to wider application in the future. The most effective form of immunotherapy thus far, capable of eradicating large tumor burdens in melanoma patients, is the ACT of TIL given to patients after lymphodepletion. As an alternative, lymphocytes engineered to recognize tumor-associated antigens can be safely infused to patients. With this approach, tumor regression is now being reported for cancers other than melanoma, but success remains constrained by the identification of antigens expressed with high specificity by cancer cells and not by normal tissues.

Expansion and characterization of human melanoma tumor-infiltrating lymphocytes (TILs)

Background

Various immunotherapeutic strategies for cancer are aimed at augmenting the T cell response against tumor cells. Adoptive cell therapy (ACT), where T cells are manipulated ex vivo and subsequently re-infused in an autologous manner, has been performed using T cells from various sources. Some of the highest clinical response rates for metastatic melanoma have been reported in trials using tumor-infiltrating lymphocytes (TILs). These protocols still have room for improvement and furthermore are currently only performed at a limited number of institutions. The goal of this work was to develop TILs as a therapeutic product at our institution.

Principal Findings

TILs from 40 melanoma tissue specimens were expanded and characterized. Under optimized culture conditions, 72% of specimens yielded rapidly proliferating TILs as defined as at least one culture reaching ≥3×10⁷ TILs within 4 weeks. Flow cytometric analyses showed that cultures were predominantly CD3+ T cells, with highly variable CD4+:CD8+ T cell ratios. In total, 148 independent bulk TIL cultures were assayed for tumor reactivity. Thirty-four percent (50/148) exhibited tumor reactivity based on IFN-γ production and/or cytotoxic activity. Thirteen percent (19/148) showed specific cytotoxic activity but not IFN-γ production and only 1% (2/148) showed specific IFN-γ production but not cytotoxic activity. Further expansion of TILs using a 14-day “rapid expansion protocol” (REP) is required to induce a 500- to 2000-fold expansion of TILs in order to generate sufficient numbers of cells for current ACT protocols. Thirty-eight consecutive test REPs were performed with an average 1865-fold expansion (+/− 1034-fold) after 14 days.

Conclusions

TILs generally expanded efficiently and tumor reactivity could be detected in vitro. These preclinical data from melanoma TILs lay the groundwork for clinical trials of ACT.

Clinical responses in a phase II study using adoptive transfer of short-term cultured tumor infiltration lymphocytes in metastatic melanoma patients

PURPOSE

Adoptive cell therapy with autologous tumor-infiltrating lymphocytes (TIL) has shown promising results in metastatic melanoma patients. Although objective response rates of over 50% have been reported, disadvantages of this approach are the labor-intensive TIL production and a very high drop-out rate of enrolled patients, limiting its widespread applicability. Previous studies showed a clear correlation between short TIL culture periods and clinical response. Therefore, we used a new TIL production technique using unselected, minimally cultured, bulk TIL (Young-TIL). The use of Young-TIL is not restricted to human leukocyte antigen (HLA)-A2 patients. The purpose of this study is to explore the efficacy and toxicity of adoptively transferred Young-TIL following lympho-depleting chemotherapy in metastatic melanoma patients, refractory to interleukin-2 and chemotherapy.

EXPERIMENTAL DESIGN

Young-TIL cultures for 90% of the patients were successfully generated, enabling the treatment of most enrolled patients. We report here the results of 20 evaluated patients.

RESULTS

Fifty percent of the patients achieved an objective clinical response according to the Response Evaluation Criteria in Solid Tumors, including two ongoing complete remissions (20+, 4+ months) and eight partial responses (progression-free survival: 18+, 13+, 10+, 9, 6+, 4, 3+, and 3 months). All responders are currently alive. Four additional patients showed disease stabilization. Side effects were transient and manageable.

CONCLUSION

We showed that lympho-depleting chemotherapy followed by transfer of short-term cultured TIL can mediate tumor regression in 50% of metastatic melanoma with manageable toxicity. The convincing clinical results combined with the simplification of the process may thus have a major effect on cell therapy of cancer.

[Application of gene therapy in tumor adoptive immunotherapy]

Adoptive cell transfer of tumor-infiltrating lymphocyte (TIL) has resulted in clear and reproducible responses in a substantial percentage (approximately 50%) of patients with metastatic melanoma. The availability of tumor reactive TIL limits the use of adoptive cell transfer for the treatment of most non-melanoma cancer patients. Recent report indicated that adoptive transfer of T lymphocytes genetically modified with T-cell receptor (TCR) against a tumor antigen resulted in objective response in melanoma patients, thus shedding light on the use of this strategy for the treatment of common epithelial cancers beyond melanoma. In this review, the current status and potential use of genetic modification in the adoptive immunotherapy of cancer patients are be discussed.

Long-term follow-up of patients treated by adoptive transfer of melanoma tumor-infiltrating lymphocytes as adjuvant therapy for stage III melanoma

The first analysis of our clinical trial on interest of using tumor-infiltrating lymphocytes (TIL) as adjuvant therapy for stage III (regional lymph nodes) melanoma was published in 2002 [5]. The aim of this paper is to update clinical results of 7 years of follow-up after the last treated patient. In the trial conducted between December 1993 and January 1999, patients without any detectable metastases after lymph node excision were randomly assigned to receive either TIL plus interleukin-2 (IL-2) for 2 months, or IL-2 only. The duration of the relapse-free interval was the primary objective. Eighty-eight patients were enrolled in the study. Currently, the last analysis performed in June 2006, after a median follow-up of 114.8 months, did not show change of non-significant extension of the relapse-free interval or overall survival. However, this second analysis strengthens our first hypothesis about the relationship between number of invaded lymph nodes and TIL treatment effectiveness. In the group with only one invaded lymph node, the estimated relapse rate was significantly lower (P (adjusted) = 0.0219) and the overall survival was increased (P (adjusted) = 0.0125) in the TIL+IL-2 arm compared with the IL-2 only arm. No differences between the two arms, either with regard to the duration of disease-free survival (P (adjusted) = 0.38) or overall survival (P (adjusted) = 0.43), were noted in the group with more than one invaded lymph node, whatever the number of invaded lymph nodes. Treatment was compatible with normal daily activity. This study, with a very long follow up (median of almost 10 years), postulates for the first time relationship between TIL efficiency in stage III melanoma (AJCC) and number of invaded lymph nodes, indicating that tumor burden might be a crucial factor in the production of an effective in vitro expansion of T cells specific for autologous tumor antigen, a finding which could be of value in future vaccine development for the treatment of melanoma.

Targeting tumours by adoptive transfer of immune cells

1. Surgery, radiotherapy and chemotherapy are the most widely used and well-established modalities for treating malignant diseases. Surgery is used to excise solid tumours and radiotherapy/chemotherapy are used for the treatment of liquid tumours and for solid tumours where there is a risk of micrometastases. A major drawback for both radiotherapy and chemotherapy is their lack of specificity for tumour cells. Both these treatments can destroy normal bone marrow cells and result in severe side-effects. 2. The impairment of haemapoiesis due to bone marrow destruction combined with the use of toxins in chemotherapy that inhibit the proliferation of immune cells leaves many patients immunocompromised. This complicates the development of prophylactic (vaccine) strategies for tumours where patients are undergoing conventional therapy. 3. An alternative approach is to expand and activate tumour-specific immune cells in vitro that can then be adoptively transferred back in large numbers. This is defined as adoptive immunotherapy and has the advantage of potentially bypassing the immuno-inhibitory effects of conventional therapies. 4. Transferred immune cells have been shown to mediate tumour regression in patients by both direct and indirect mechanisms. The immune cells used include tumour reactive T lymphocytes and dendritic cells, which elicit tumour specific responses. 5. Many novel cell-based immunotherapeutic strategies developed in murine tumour models are now being applied in human clinical trials. The malignancies targeted include melanoma, chronic myelogenous leukaemia and breast, ovarian, colon and kidney cancers. In the present review, we discuss these novel cell-based strategies and the implications they have for the future treatment of human malignancies.

Combination of tumor site-located CTL-associated antigen-4 blockade and systemic regulatory T-cell depletion induces tumor-destructive immune responses

Accumulating data indicate that tumor-infiltrating regulatory T cells (Treg) are present in human tumors and locally suppress antitumor immune cells. In this study, we found an increased Treg/CD8 ratio in human breast and cervical cancers. A similar intratumoral lymphocyte pattern was observed in a mouse model for cervical cancer (TC-1 cells). In this model, systemic Treg depletion was inefficient in controlling tumor growth. Furthermore, systemic CTL-associated antigen-4 (CTLA-4) blockade, an approach that can induce tumor immunity in other tumor models, did not result in TC-1 tumor regression but led to spontaneous development of autoimmune hepatitis. We hypothesized that continuous expression of an anti-CTLA-4 antibody localized to the tumor site could overcome Treg-mediated immunosuppression and locally activate tumor-reactive CD8+ cells, without induction of autoimmunity. To test this hypothesis, we created TC-1 cells that secrete a functional anti-CTLA-4 antibody (TC-1/alphaCTLA-4-gamma1 cells). When injected into immunocompetent mice, the growth of TC-1/alphaCTLA-4-gamma1 tumors was delayed compared with control TC-1 cells and accompanied by a reversion of the intratumoral Treg/CD8 ratio due to an increase in tumor-infiltrating IFNgamma-producing CD8+ cells. When local anti-CTLA-4 antibody production was combined with Treg inhibition, permanent TC-1 tumor regression and immunity was induced. Importantly, no signs of autoimmunity were detected in mice that received local CTLA-4 blockade alone or in combination with Treg depletion.

Infusion of Melan-A/Mart-1 specific tumor-infiltrating lymphocytes enhanced relapse-free survival of melanoma patients

Adoptive therapy of cancer has been mostly tested in advanced cancer patients using tumor-infiltrating lymphocytes (TIL). Following discouraging results likely due to poor tumor-specificity of TIL and/or high tumor burden, recent studies reiterate the enormous potential of this therapy, particularly in melanoma. We had performed a phase II/III randomised trial on 88 stage III melanoma patients, who received autologous TIL plus IL-2 or IL-2 alone, after complete tumour resection. We reported previously clinical and immunological results supporting the ability of tumor reactive TIL infusion to prevent further development of the melanoma disease and to increase overall survival of patients bearing only one tumor invaded lymph node. The absence of correlation between overall and disease-free survival and the amount of infused tumor-specific TIL suggested that therapeutic efficiency might depend on other parameters such as antigen specificity, function or persistence of TIL. Here we studied the recognition of a panel of 38 shared tumor-associated antigens (TAA) by TIL infused to the patients included in this assay, in order to determine if treatment outcome could correlate with particular antigen specificities of infused TIL. Results show that the infusion of Melan-A/MART-1 reactive TIL appears to be associated with a longer relapse-free survival for HLA-A2 patients. These results further support the relevance of Melan-A/MART-1 antigen as a prime target for immunotherapy protocols in melanoma.

T cell immunotherapy

Adoptive T cell immunotherapy is the isolation of tumor-specific T cells from a cancer patient, in vitro activation and expansion of these T cells, and re-infusion of the T cells to the patient. In a small percentage of patients with tumor types susceptible to immune modulation, adoptive therapy has proven to be highly effective. The use of adoptive therapy has several limitations which are being actively investigated today. T cells from various sources are being isolated for adoptive therapy: lymphocytes can be isolated from tumor lesions, from lymph nodes draining the tumor or a tumor vaccine site, or from peripheral blood lymphocytes stimulated with tumor antigens in vitro. Recent advances in T cell therapy include enhanced efficacy of T cell therapy following non-myeloablative chemotherapy and genetic modification of T cells for use in adoptive therapy. Clinical trials using gene-modified T cells with improved activation, lifespan, and tumor targeting are on the horizon. It is likely that adoptive immunotherapy will remain a fertile area for investigation resulting in advances in the fields of T cell biology and gene therapy. Adoptive therapy for cancer will become widespread only after its clinical benefit for sizeable patient populations has been established.

Gene transfer of tumor-reactive TCR confers both high avidity and tumor reactivity to nonreactive peripheral blood mononuclear cells and tumor-infiltrating lymphocytes

Cell-based antitumor immunity is driven by CD8(+) cytotoxic T cells bearing TCR that recognize specific tumor-associated peptides bound to class I MHC molecules. Of several cellular proteins involved in T cell:target-cell interaction, the TCR determines specificity of binding; however, the relative amount of its contribution to cellular avidity remains unknown. To study the relationship between TCR affinity and cellular avidity, with the intent of identifying optimal TCR for gene therapy, we derived 24 MART-1:27-35 (MART-1) melanoma Ag-reactive tumor-infiltrating lymphocyte (TIL) clones from the tumors of five patients. These MART-1-reactive clones displayed a wide variety of cellular avidities. alpha and beta TCR genes were isolated from these clones, and TCR RNA was electroporated into the same non-MART-1-reactive allogeneic donor PBMC and TIL. TCR recipient cells gained the ability to recognize both MART-1 peptide and MART-1-expressing tumors in vitro, with avidities that closely corresponded to the original TCR clones (p = 0.018-0.0003). Clone DMF5, from a TIL infusion that mediated tumor regression clinically, showed the highest avidity against MART-1 expressing tumors in vitro, both endogenously in the TIL clone, and after RNA electroporation into donor T cells. Thus, we demonstrated that the TCR appeared to be the core determinant of MART-1 Ag-specific cellular avidity in these activated T cells and that nonreactive PBMC or TIL could be made tumor-reactive with a specific and predetermined avidity. We propose that inducing expression of this highly avid TCR in patient PBMC has the potential to induce tumor regression, as an "off-the-shelf" reagent for allogeneic melanoma patient gene therapy.

Modulation by IL-2 of CD70 and CD27 expression on CD8+ T cells: importance for the therapeutic effectiveness of cell transfer immunotherapy

Proper T cell function relies on the integration of signals delivered by Ag, cytokine, and costimulatory receptors. In this study, the interactions between IL-2, CD27, and its ligand CD70 and their effects on human T cell function were examined. Unstimulated CD8(+) T cells expressed relatively low levels of CD70 and high levels of CD27. Incubation in vitro with high doses of IL-2 (3,000 IU/ml) or administration of IL-2 in vivo resulted in substantial up-regulation of CD70 expression and the concomitant loss of cell surface CD27 expression on CD8(+) cells. Withdrawal of IL-2 from activated CD8(+) T cells that had been maintained in IL-2 resulted in a reversal of the expression of these two markers, whereas reciprocal changes were seen following treatment of PBMCs with IL-2. The proliferation observed in cells stimulated with IL-2 primarily occurred in a subset of the CD70(+)CD8(+) T cells that up-regulated IL-2 receptor expression but did not occur in CD70(-)CD8(+) T cells. Blocking CD70 resulted in a significant reduction of T cell proliferation induced by high-dose IL-2, indicating that the interaction of CD70 with CD27 played a direct role in T cell activation mediated by IL-2. Finally, studies conducted on tumor-infiltrating lymphocyte (TIL) samples that were administered to melanoma patients indicated that the size of the pool of CD27(+)CD8(+) T cells in bulk TILs was highly associated (p = 0.004) with the ability of these TILs to mediate tumor regression following adoptive transfer.

Adoptive cell therapy for metastatic melanoma patients: pre-clinical development at the Sheba Medical Center

BACKGROUND

Metastatic melanoma is an aggressive and highly malignant cancer. The 5 year survival rate of patients with metastatic disease is less than 5% with a median survival of only 6-10 months. Drugs like dacarbazin (DTIC) as a single agent or in combination with other chemotherapy agents have a response rate of 15-30%, but the duration of response is usually short with no impact on survival. Interleukin-2-based immunotherapy has shown more promising results. The National Institutes of Health recently reported that lymphodepleting chemotherapy, followed by an adoptive transfer of large numbers of anti-tumor specific tumor-infiltrating lymphocytes, resulted in an objective regression in 51% of patients.

OBJECTIVES

To introduce the TIL technology to advanced metastatic melanoma patients in Israel.

METHODS

We generated TIL cultures from tumor tissue, choosing those with specific activity against melanoma and expanding them to large numbers.

RESULTS

TIL cultures from nine patients were established and examined for their specific activity against the patients' autologous tumor cells. Twelve TIL cultures derived from 5 different patients showed the desired anti-tumor activity, making those 5 patients potential candidates for the therapy.

CONCLUSIONS

Pre-clinical studies of the TIL technology in a clinical laboratory set-up were performed successfully and this modality is ready for treating metastatic melanoma patients at the Sheba Medical Center's Ella Institute.

Immunotherapy for gynaecological malignancies

Gynaecological malignancies, excluding breast cancer, cause approximately 25,000 deaths yearly among women in the US. Therefore, novel approaches for the prevention or treatment of these diseases are urgently required. In the case of cervical cancer, human papillomavirus (HPV) xenoantigens are readily recognised by the immune system, and their targeting has shown great promise in preclinical models of therapeutic vaccination and in clinical studies of preventative vaccination. A growing body of evidence indicates that ovarian cancer is also immunogenic and can thus be targeted through immunotherapy. This review outlines the principles and problems of immunotherapy for cervical and ovarian cancer, including the authors' personal assessment.

Survival, persistence, and progressive differentiation of adoptively transferred tumor-reactive T cells associated with tumor regression

Objective clinical responses have been observed in approximately 50% of patients who received non-myeloablative chemotherapy prior to the adoptive transfer of autologous melanoma-reactive tumor-infiltrating lymphocytes (TILs). Recent studies carried out through the use of antibodies directed against T-cell-receptor beta chain variable region (TRBV) products, as well as by direct sequencing of the expressed TRBV gene products, indicated that clinical responses in this trial were associated with the level of persistence of adoptively transferred T cells. In an attempt to further characterize T cells that persist in vivo following adoptive transfer, five dominant T-cell clonotypes were identified in TIL 2035, an adoptively transferred TIL that was associated with the complete regression of multiple metastases. The most highly persistent clonotype, which expressed the BV1 TR gene product, recognized the MAGE-6 cancer/testis antigen in the context of HLA-A23. This clonotype was detected in peripheral blood for over 16 months following adoptive transfer, expressed relatively higher levels of the co-stimulatory markers CD28 and CD27, and possessed telomeres that were long relative to other clonotypes present in TIL 2035 that showed only short-term persistence. The long-term persistent BV1 clonotype appeared to differentiate more slowly toward an end-stage effector in vivo than short-term persistent clonotypes, as manifested by the downregulation of CD28, CD27, and CD45RO and upregulation of CD57 and CD45RA expression on these T cells. These results indicated that the differentiation stage and replicative history of individual TIL clonotypes might be associated with their ability to survive and to persist in vivo, and progressive differentiation of the persistent clonotypes occurred following adoptive transfer.

Finding a place for tumor-specific T cells in targeted cancer therapy

A goal in cancer therapeutics is to develop targeted modalities that distinguish malignant from normal cells. T cells can discriminate diseased cells based on subtle alterations in peptides displayed in association with MHC molecules at the cell surface. Recent success using the adoptive transfer of tumor-specific T cells has fueled optimism that this approach may find a place as a targeted therapy for some human cancers.

Vaccine-stimulated, adoptively transferred CD8+ T cells traffic indiscriminately and ubiquitously while mediating specific tumor destruction

It has been suggested that antitumor T cells specifically traffic to the tumor site, where they effect tumor destruction. To test whether tumor-reactive CD8(+) T cells specifically home to tumor, we assessed the trafficking of gp100-specific pmel-1 cells to large, vascularized tumors that express or do not express the target Ag. Activation of tumor-specific CD8(+) pmel-1 T cells with IL-2 and vaccination with an altered peptide ligand caused regression of gp100-positive tumors (B16), but not gp100-negative tumors (methylcholanthrene 205), implanted on opposing flanks of the same mouse. Surprisingly, we found approximately equal and very large numbers of pmel-1 T cells (>25% of all lymphocytes) infiltrating both Ag-positive and Ag-negative tumors. We also found evidence of massive infiltration and proliferation of activated antitumor pmel-1 cells in a variety of peripheral tissues, including lymph nodes, liver, spleen, and lungs, but not peripheral blood. Most importantly, evidence for T cell function, as measured by production of IFN-gamma, release of perforin, and activation of caspase-3 in target cells, was confined to Ag-expressing tumor. We thus conclude that CD8(+) T cell-mediated destruction of tumor is the result of specific T cell triggering at the tumor site. The ability to induce ubiquitous homing and specific tumor destruction may be important in the case of noninflammatory metastatic tumor foci.