Tissues in different anatomical sites can sculpt and vary the tumor microenvironment to affect responses to therapy.

The tumor microenvironment can promote tumor growth and reduce treatment efficacy. Tumors can occur in many sites in the body, but how surrounding normal tissues at different anatomical sites affect tumor microenvironments and their subsequent response to therapy is not known.We demonstrated that tumors from renal, colon, or prostate cell lines in orthotopic locations responded to immunotherapy consisting of three agonist antibodies, termed Tri-mAb, to a much lesser extent than the same tumor type located subcutaneously. A tissue-specific response to Tri-mAb was confirmed by ex vivo separation of subcutaneous (SC) or orthotopic tumor cells from stromal cells, followed by reinjection of tumor cells into the opposite site. Compared with SC tumors, orthotopic tumors had a microenvironment associated with a type 2 immune response, related to immunosuppression, and an involvement of alternatively activated macrophages in the kidney model. Orthotopic kidney tumors were more highly vascularized than SC tumors. Neutralizing the macrophage- and Th2-associated molecules chemokine (C-C motif) ligand 2 or interleukin-13 led to a significantly improved therapeutic effect. This study highlights the importance of the tissue of implantation in sculpting the tumor microenvironment. These are important fundamental issues in tumor biology and crucial factors to consider in the design of experimental models and treatment strategies.

Persistence and efficacy of second generation CAR T cell against the LeY antigen in acute myeloid leukemia.

In a phase I study of autologous chimeric antigen receptor (CAR) anti-LeY T-cell therapy of acute myeloid leukemia (AML), we examined the safety and postinfusion persistence of adoptively transferred T cells. Following fludarabine-containing preconditioning, four patients received up to 1.3 × 109 total T cells, of which 14-38% expressed the CAR. Grade 3 or 4 toxicity was not observed. One patient achieved a cytogenetic remission whereas another with active leukemia had a reduction in peripheral blood (PB) blasts and a third showed a protracted remission. Using an aliquot of In111-labeled CAR T cells, we demonstrated trafficking to the bone marrow (BM) in those patients with the greatest clinical benefit. Furthermore, in a patient with leukemia cutis, CAR T cells infiltrated proven sites of disease. Serial PCR of PB and BM for the LeY transgene demonstrated that infused CAR T cells persisted for up to 10 months. Our study supports the feasibility and safety of CAR-T-cell therapy in high-risk AML, and demonstrates durable in vivo persistence.

Autoimmunity associated with immunotherapy of cancer.

In this age of promise of new therapies for cancer, immunotherapy is emerging as an exciting treatment option for patients. Vaccines and cytokines are being tested extensively in clinical trials, and strategies using monoclonal antibodies and cell transfer are mediating dramatic regression of tumors in patients with certain malignancies. However, although initially advocated as being more specific for cancer and having fewer side effects than conventional therapies, it is becoming increasingly clear that many immunotherapies can lead to immune reactions against normal tissues. Immunotoxicities resulting from treatment can range from relatively minor conditions, such as skin depigmentation, to severe toxicities against crucial organ systems, such as liver, bowel, and lung. Treatment-related toxicity has correlated with better responses in some cases, and it is probable that serious adverse events from immune-mediated reactions will increase in frequency and severity as immunotherapeutic approaches become more effective. This review introduces immunotherapeutic approaches to cancer treatment, provides details of toxicities arising from therapy, and discusses future potential ways to avoid or circumvent these side effects.

Perforin-mediated suppression of B-cell lymphoma.

In the present study, we have examined the effect of perforin (pfp) deficiency in 4 models of mouse B-cell lymphomagenesis. We have examined pfp loss on the background of either Mlh1 tumor suppressor allele loss or oncogene expression [Ig heavy chain (Emu)-v-Abl, Emu-myc, and vav-bcl2]. Pfp was shown to act as a suppressor of B-cell malignancies characteristically driven by v-Abl or bcl-2, whereas Mlh loss cooperated in accelerating spontaneous B-cell lymphomas characteristic of pfp loss. No protective role for pfp was observed in the more aggressive Emu-myc model of B-cell lymphoma. These transgenic models have allowed us to distinguish the role of pfp in surveillance of B-cell lymphomagenesis, as opposed to its loss simply driving the onset of a spontaneous lymphoma characteristic of pfp deficiency.

Adoptive immunotherapy combined with intratumoral TLR agonist delivery eradicates established melanoma in mice.

Toll-like receptor (TLR) agonists can trigger broad inflammatory responses that elicit rapid innate immunity and promote the activities of lymphocytes, which can potentially enhance adoptive immunotherapy in the tumor-bearing setting. In the present study, we found that Polyinosinic:Polycytidylic Acid [Poly(I:C)] and CpG oligodeoxynucleotide 1826 [CpG], agonists for TLR 3 and 9, respectively, potently activated adoptively transferred T cells against a murine model of established melanoma. Intratumoral injection of Poly(I:C) and CpG, combined with systemic transfer of activated pmel-1 T cells, specific for gp100(25-33), led to enhanced survival and eradication of 9-day established subcutaneous B16F10 melanomas in a proportion of mice. A series of survival studies in knockout mice supported a key mechanistic pathway, whereby TLR agonists acted via host cells to enhance IFN-γ production by adoptively transferred T cells. IFN-γ, in turn, enhanced the immunogenicity of the B16F10 melanoma line, leading to increased killing by adoptively transferred T cells. Thus, this combination approach counteracted tumor escape from immunotherapy via downregulation of immunogenicity. In conclusion, TLR agonists may represent advanced adjuvants within the setting of adoptive T-cell immunotherapy of cancer and hold promise as a safe means of enhancing this approach within the clinic.

Generating CAR T cells from tumor-infiltrating lymphocytes.

Background: Tumor-infiltrating lymphocytes (TILs) and chimeric antigen receptor (CAR) T-cell therapies have demonstrated promising, though limited, efficacy against melanoma. Methods: We designed a model system to explore the efficacy of dual specific T cells derived from melanoma patient TILs by transduction with a Her2-specific CAR. Results: Metastatic melanoma cells in our biobank constitutively expressed Her2 antigen. CAR-TIL produced greater amounts of IFN compared with parental TIL, when co-cultured with Her2 expressing tumor lines, including autologous melanoma tumor lines, although no consistent increase in cytotoxicity by TIL was afforded by expression of a CAR. Results of an in vivo study in NSG mice demonstrated tumor shrinkage when CAR-TILs were used in an adoptive cell therapy protocol. Conclusion: Potential limitations of transduced TIL in our study included limited proliferative potential and a terminally differentiated phenotype, which would need addressing in further work before consideration of clinical translation.

Three agonist antibodies in combination with high-dose IL-2 eradicate orthotopic kidney cancer in mice.

BACKGROUND: Combination immunotherapies can be effective against subcutaneous tumors in mice but the effect against orthotopic malignant disease is less well characterized. In particular, a combination of three agonist antibodies, termed Tri-mAb, consisting of anti-DR5, anti-CD40 and anti-CD137 has previously been demonstrated to eradicate a large proportion of subcutaneous renal cell carcinoma (Renca) tumors (75% long-term survival), but the effect against orthotopic disease is not known. PURPOSE: To determine the relative response of orthotopic tumors, we inoculated Renca into the kidney followed by treatment with Tri-mAb. RESULTS: We found that orthotopic tumors responded much less to treatment (approximately 13% survival), but a significant improvement in survival was achieved through the addition of IL-2 to the treatment regimen (55% survival). All three agonist antibodies and high dose IL-2, 100,000 IU for up to six doses, were required. CD8+ T cells were also required for optimal anti-tumor responses. Coadministration of IL-2 led to enhanced T cell activity as demonstrated by an increased frequency of IFN-gamma-producing T cells in tumor-draining lymph nodes, which may have contributed to the observed improvement of therapy against kidney tumors. IMPLICATIONS: Responses of subcutaneous tumors to immunotherapy do not necessarily reflect how orthotopic tumors respond. The use of combination immunotherapy stimulating multiple facets of immunity and including cytokine support for T cells can induce effective anti-tumor responses against orthotopic and metastatic tumors.

Host perforin reduces tumor number but does not increase survival in oncogene-driven mammary adenocarcinoma.

The concept of tumor immune surveillance has been supported by several recent studies in mice which show that immune effector mechanisms suppress hematologic malignancy. However, because the most common forms of human cancer are epithelial in origin, and comparatively very little data supports the immune surveillance of epithelial malignancies, we have chosen to evaluate the role of perforin-mediated cytotoxicity in the prevention of BALB/c Her2/neu-induced mammary cancer. Interestingly, perforin significantly delayed the onset of mammary tumorigenesis and reduced the number of mammary tumors without improving survival. Natural killer cell, but not CD8+ T cell, depletion resulted in a similar phenotype to perforin deficiency in this regard. Histologic analysis further indicated that the effect of perforin was most evident during the earliest stages of carcinogenesis rather than prior to or during the hyperplastic phase. This data suggests that perforin may mediate some suppression of epithelial carcinogenesis by intervening early in the tumor development process.

Combined natural killer T-cell based immunotherapy eradicates established tumors in mice.

A rational monoclonal antibody (mAb)-based antitumor therapy approach has previously been shown to eradicate various established experimental and carcinogen-induced tumors in a majority of mice. This therapy comprised an agonistic mAb reactive with tumor necrosis factor-related apoptosis-inducing ligand receptor (DR5), expressed by tumor cells, an agonistic anti-CD40 mAb to mature dendritic cells, and an agonistic anti-4-1BB mAb to costimulate CD8(+) T cells. Because agonists of CD40 have been toxic in patients, we were interested in substituting anti-CD40 mAb with other dendritic cell-maturing agents, such as glycolipid ligands recognized by invariant natural killer T (iNKT) cells. Here, we show that CD1d-restricted glycolipid ligands for iNKT cells effectively substitute for anti-CD40 mAb and reject established experimental mouse breast and renal tumors when used in combination with anti-DR5 and anti-4-1BB mAbs (termed "NKTMab" therapy). NKTMab therapy-induced tumor rejection was dependent on CD4(+) and CD8(+) T cells, NKT cells, and the cytokine IFN-gamma. NKTMab therapy containing either alpha-galactosylceramide (alpha-GC) or alpha-C-galactosylceramide (alpha-c-GC) at high concentrations induced similar rates of tumor rejection in mice; however, toxicity was observed at the highest doses of alpha-GC (>250 ng/injection), limiting the use of this glycolipid. By contrast, even very low doses of alpha-c-GC (25 ng/injection) retained considerable antitumor activity when used in combination with anti-DR5/anti-4-1BB, and thus, alpha-c-GC showed a considerably greater therapeutic index. In summary, sequential tumor cell apoptosis and amplification of dendritic cell function by NKT cell agonists represents an exciting and novel approach for cancer treatment.

A phase I study on adoptive immunotherapy using gene-modified T cells for ovarian cancer.

PURPOSE: A phase I study was conducted to assess the safety of adoptive immunotherapy using gene-modified autologous T cells for the treatment of metastatic ovarian cancer. EXPERIMENTAL DESIGN: T cells with reactivity against the ovarian cancer-associated antigen alpha-folate receptor (FR) were generated by genetic modification of autologous T cells with a chimeric gene incorporating an anti-FR single-chain antibody linked to the signaling domain of the Fc receptor gamma chain. Patients were assigned to one of two cohorts in the study. Eight patients in cohort 1 received a dose escalation of T cells in combination with high-dose interleukin-2, and six patients in cohort 2 received dual-specific T cells (reactive with both FR and allogeneic cells) followed by immunization with allogeneic peripheral blood mononuclear cells. RESULTS: Five patients in cohort 1 experienced some grade 3 to 4 treatment-related toxicity that was probably due to interleukin-2 administration, which could be managed using standard measures. Patients in cohort 2 experienced relatively mild side effects with grade 1 to 2 symptoms. No reduction in tumor burden was seen in any patient. Tracking 111In-labeled adoptively transferred T cells in cohort 1 revealed a lack of specific localization of T cells to tumor except in one patient where some signal was detected in a peritoneal deposit. PCR analysis showed that gene-modified T cells were present in the circulation in large numbers for the first 2 days after transfer, but these quickly declined to be barely detectable 1 month later in most patients. An inhibitory factor developed in the serum of three of six patients tested over the period of treatment, which significantly reduced the ability of gene-modified T cells to respond against FR+ tumor cells. CONCLUSIONS: Large numbers of gene-modified tumor-reactive T cells can be safely given to patients, but these cells do not persist in large numbers long term. Future studies need to employ strategies to extend T cell persistence. This report is the first to document the use of genetically redirected T cells for the treatment of ovarian cancer.

Dual-specific T cells combine proliferation and antitumor activity.

An effective immune response against cancer requires the activation and expansion of specific T cells. Tumor antigens, however, are generally poor immunogens. To achieve expansion of tumor-reactive T cells in vivo, we used a strategy of generating dual-specific T cells that could respond to a powerful immunogen while also possessing tumor reactivity. We generated dual-specific T cells by genetic modification of alloreactive T cells with a chimeric receptor recognizing folate-binding protein, an ovarian cancer-associated antigen. Mouse dual-specific T cells responded in vitro to both allogeneic antigen and tumor cells expressing folate-binding protein, and expanded in number in vivo in response to immunization with allogeneic cells. Most importantly, the combination of dual-specific T cells and immunization had an antitumor effect in vivo. We also generated human dual-specific T cells and characterized the dual-specific nature of individual clones. Assigning the tasks of expansion and tumor reactivity to different receptors within the same lymphocyte may help to overcome the problem of poor immunogenicity of tumor antigens.

Mobile Health Intervention to Increase Oral Cancer Therapy Adherence in Patients With Chronic Myeloid Leukemia (The REMIND System): Clinical Feasibility and Acceptability Assessment.

BACKGROUND: Optimal dosing of oral tyrosine kinase inhibitor therapy is critical to treatment success and survival of patients with chronic myeloid leukemia (CML). Drug intolerance secondary to toxicities and nonadherence are significant factors in treatment failure. OBJECTIVE: The objective of this study was to develop and pilot-test the clinical feasibility and acceptability of a mobile health system (REMIND) to increase oral drug adherence and patient symptom self-management among people with CML (chronic phase). METHODS: A multifaceted intervention was iteratively developed using the intervention development framework by Schofield and Chambers, consisting of defining the patient problem and iteratively refining the intervention. The clinical feasibility and acceptability were examined via patient and intervention nurse interviews, which were audiotaped, transcribed, and deductively content analyzed. RESULTS: The intervention comprised 2 synergistically operating elements: (1) daily medication reminders and routine assessment of side effects with evidence-based self-care advice delivered in real time and (2) question prompt list (QPL) questions and routinely collected individual patient adherence and side effect profile data used to shape nurses' consultations, which employed motivational interviewing to support adoption of self-management behaviors. A total of 4 consultations and daily alerts and advice were delivered over 10 weeks. In total, 58% (10/17) of patients and 2 nurses participated in the pilot study. Patients reported several benefits of the intervention: help in establishing medication routines, resolution of symptom uncertainty, increased awareness of self-care, and informed decision making. Nurses also endorsed the intervention: it assisted in establishing pill-taking routines and patients developing effective solutions to adherence challenges. CONCLUSIONS: The REMIND system with nurse support was usable and acceptable to both patients and nurses. It has the potential to improve adherence and side-effect management and should be further evaluated.

An ultrastructural investigation of tumors undergoing regression mediated by immunotherapy.

While immunotherapy employing chimeric antigen receptor (CAR) T cells can be effective against a variety of tumor types, little is known about what happens within the tumor at an ultrastructural level during tumor regression. Here, we used transmission electron microscopy to investigate morphologic and cellular features of tumors responding to immunotherapy composed of adoptive transfer of dual-specific CAR T cells and a vaccine, supported by preconditioning irradiation and interleukin-2. Tumors responded rapidly, and large areas of cell death were apparent by 4 days after treatment. The pleomorphic and metabolically active nature of tumor cells and phagocytic activity of macrophages were apparent in electron microscopic images of tumors prior to treatment. Following treatment, morphologic features of various types of tumor cell death were observed, including apoptosis, paraptosis and necrosis. Large numbers of lipid droplets were evident in tumor cells undergoing apoptosis. Macrophages were the predominant leukocyte type infiltrating tumors before treatment. Macrophages decreased in frequency and number after treatment, whereas an increasing accumulation of neutrophils and T lymphocytes was observed following treatment. Phagocytic activity of macrophages and neutrophils was apparent, while T cells could be observed in close association with tumor cells with potential immunological synapses present. These observations highlight the cellular composition and ultrastructural appearance of tumors undergoing regression mediated by immunotherapy.

Dual-specific Chimeric Antigen Receptor T Cells and an Indirect Vaccine Eradicate a Variety of Large Solid Tumors in an Immunocompetent, Self-antigen Setting.

Purpose: While adoptive transfer of T cells bearing a chimeric antigen receptor (CAR) can eliminate substantial burdens of some leukemias, the ultimate challenge remains the eradication of large solid tumors for most cancers. We aimed to develop an immunotherapy approach effective against large tumors in an immunocompetent, self-antigen preclinical mouse model.Experimental Design: In this study, we generated dual-specific T cells expressing both a CAR specific for Her2 and a TCR specific for the melanocyte protein (gp100). We used a regimen of adoptive cell transfer incorporating vaccination (ACTIV), with recombinant vaccinia virus expressing gp100, to treat a range of tumors including orthotopic breast tumors and large liver tumors.Results: ACTIV therapy induced durable complete remission of a variety of Her2+ tumors, some in excess of 150 mm2, in immunocompetent mice expressing Her2 in normal tissues, including the breast and brain. Vaccinia virus induced extensive proliferation of T cells, leading to massive infiltration of T cells into tumors. Durable tumor responses required the chemokine receptor CXCR3 and exogenous IL2, but were independent of IFNγ. Mice were resistant to tumor rechallenge, indicating immune memory involving epitope spreading. Evidence of limited neurologic toxicity was observed, associated with infiltration of cerebellum by T cells, but was only transient.Conclusions: This study supports a view that it is possible to design a highly effective combination immunotherapy for solid cancers, with acceptable transient toxicity, even when the target antigen is also expressed in vital tissues. Clin Cancer Res; 23(10); 2478-90. ©2016 AACR.

Activation of NK cell cytotoxicity.

Natural killer (NK) cells are innate effector lymphocytes necessary for defence against stressed, microbe-infected, or malignant cells. NK cells kill target cells by either of two major mechanisms that require direct contact between NK cells and target cells. In the first pathway, cytoplasmic granule toxins, predominantly a membrane-disrupting protein known as perforin, and a family of structurally related serine proteases (granzymes) with various substrate specificities, are secreted by exocytosis and together induce apoptosis of the target cell. The granule-exocytosis pathway potently activates cell-death mechanisms that operate through the activation of apoptotic cysteine proteases (caspases), but can also cause cell death in the absence of activated caspases. The second pathway involves the engagement of death receptors (e.g. Fas/CD95) on target cells by their cognate ligands (e.g. FasL) on NK cells, resulting in classical caspase-dependent apoptosis. The comparative role of these pathways in the pathophysiology of many diseases is being dissected by analyses of gene-targeted mice that lack these molecules, and humans who have genetic mutations affecting these pathways. We are also now learning that the effector function of NK cells is controlled by interactions involving specific NK cell receptors and their cognate ligands, either on target cells, or other cells of the immune system. This review will discuss the functional importance of NK cell cytotoxicity and the receptor/ligand interactions that control these processes.

Expression of a Chimeric Antigen Receptor in Multiple Leukocyte Lineages in Transgenic Mice.

Genetically modified CD8+ T lymphocytes have shown significant anti-tumor effects in the adoptive immunotherapy of cancer, with recent studies highlighting a potential role for a combination of other immune subsets to enhance these results. However, limitations in present genetic modification techniques impose difficulties in our ability to fully explore the potential of various T cell subsets and assess the potential of other leukocytes armed with chimeric antigen receptors (CARs). To address this issue, we generated a transgenic mouse model using a pan-hematopoietic promoter (vav) to drive the expression of a CAR specific for a tumor antigen. Here we present a characterization of the immune cell compartment in two unique vav-CAR transgenic mice models, Founder 9 (F9) and Founder 38 (F38). We demonstrate the vav promoter is indeed capable of driving the expression of a CAR in cells from both myeloid and lymphoid lineage, however the highest level of expression was observed in T lymphocytes from F38 mice. Lymphoid organs in vav-CAR mice were smaller and had reduced cell numbers compared to the wild type (WT) controls. Furthermore, the immune composition of F9 mice differed greatly with a significant reduction in lymphocytes found in the thymus, lymph node and spleen of these mice. To gain insight into the altered immune phenotype of F9 mice, we determined the chromosomal integration site of the transgene in both mouse strains using whole genome sequencing (WGS). We demonstrated that compared to the 7 copies found in F38 mice, F9 mice harbored almost 270 copies. These novel vav-CAR models provide a ready source of CAR expressing myeloid and lymphoid cells and will aid in facilitating future experiments to delineate the role for other leukocytes for adoptive immunotherapy against cancer.

Cross-talk between tumors can affect responses to therapy.

Advanced stages of cancer often involve multiple tumors in different locations in the body. These tumors are associated with a microenvironment that can influence tumor responses to immunotherapy. Whether tumors and their disparate microenvironment can interact together at distance in a multiple tumor setting, through a form of cross-talk, and affect their responses to immunotherapy has never been described. Our study investigated the cross-talk between two tumors with disparate microenvironments in a mouse model. We demonstrated that immunosuppressive visceral tumors could influence distant subcutaneous (SC) tumors to render them resistant to immunotherapy. We observed distinct modifications in the SC tumor microenvironment following cross-talk with kidney tumors that exhibit a type-2 macrophage-related immunosuppressive microenvironment. Indeed, when a concomitant kidney tumor was present in the mouse, the SC tumors were highly infiltrated with M2 macrophages and had a reduced T cell and NK cell effector immune profile. Finally, blocking the M2-associated chemokine CCL2 or depleting macrophages, significantly improved the effect of immunotherapy on growth of SC tumors in the presence of concomitant kidney tumors. This work emphasizes the potential negative influence that a tumor, with a strong immunosuppressive microenvironment, can exert on distant tumors that would normally be treatment-responsive. This report may lead to a new vision of the prioritization in the treatment of advanced metastatic cancer.

Psychological distress, quality of life, symptoms and unmet needs of colorectal cancer survivors near the end of treatment.

PURPOSE: This study investigated psychological morbidity, quality of life (QoL), colorectal cancer (CRC)-specific symptoms and supportive care needs in a CRC population at the end of treatment (EOT). METHODS: CRC survivors (n = 152) completed a post-treatment baseline questionnaire as part of a multisite supportive care randomised controlled trial (SurvivorCare). CRC survivors had completed treatment with curative intent within 0 to 6 months. Measures are as follows: Brief Symptom Inventory 18 (BSI-18) (psychological morbidity), EORTC QLQ-C30 and QLQ-CR29 (QoL and CRC-specific symptoms and problems) and Cancer Survivors' Unmet Needs (CaSUN) measure with a simplified response format (unmet needs). Linear regression models were used to compare participants' QoL with a general population sample. Correlation analysis examined associations between psychological morbidity, QoL and CRC-specific symptoms and problems. RESULTS: Average participant age was 64 years, and 51% were male. The majority (68%) had stage 3 disease. In comparison to population norms, CRC survivors had lower depression and anxiety scores (47.4 and 45.6, respectively) but higher somatisation, and lower role, cognitive and social functioning (p < 0.001). CRC survivors had higher fatigue, nausea/vomiting, appetite loss, diarrhoea and financial problems (all p < 0.001), as well as pain (p = 0.002) and constipation (p = 0.019). CRC-specific psychological scores were positively correlated with all three BSI domain scores, and pain and fatigue symptom scores on the QLQ-C30 while negatively correlated with all five functional scales of the QLQ-C30. CONCLUSIONS: CRC survivors reported good mental health at EOT. Role and social functioning were impaired compared to population norms, possibly related to physical symptoms. IMPLICATIONS FOR CANCER SURVIVORS: Findings may help guide consultations with patients and inform the design of more tailored supportive care interventions. TRIAL REGISTRATION: ACTRN12610000207011.

Redirecting migration of T cells to chemokine secreted from tumors by genetic modification with CXCR2.

T-cell-based immunotherapies provide a promising means of cancer treatment although durable antitumor responses are infrequent. A potential reason for these shortcomings may lie in the observed lack of trafficking of specific T cells to tumor. Our increasing knowledge of the process of trafficking involving adhesion molecules and chemokines affords us the opportunity to intervene and correct deficiencies in this process. Chemokines can be expressed by a range of tumors and may serve as suitable targets for directing specific T cells toward tumor. We initially sought to identify which chemokines were produced by a range of human tumor cell lines, and which chemokines and chemokine receptors were expressed by cultured T cells. We identified two chemokines: Growth-Regulated Oncogene-alpha (Gro-alpha; CXCL1) and Regulated on Activation Normal T Cell-Expressed and Secreted (RANTES; CCL5), to be secreted by several human tumor cell lines. Expression was also detected in fine-needle aspirates of melanoma from patients. In addition, we determined the expression of several chemokine receptors on cultured human T cells including CCR1, CCR2, CCR4, CCR5, CXCR3, and CXCR4. Cultured, activated human T cells expressed the chemokines lymphotactin (XCL1), RANTES, macrophage inflammatory protein-1 alpha (MIP-1 alpha; CCL3) and MIP-1 beta (CCL4), but no appreciable Gro-alpha. In a strategy to direct T cells toward chemokines expressed by tumors we chose Gro-alpha as the target chemokine because it was produced by tumor and not by T cells themselves. However, T cells did not express the receptor for Gro-alpha, CXCR2, and therefore, T cells were transduced with a retroviral vector encoding CXCR2. Calcium ion mobilization, an important first step in chemokine receptor signaling, was subsequently demonstrated in transduced T cells in response to Gro-alpha. In addition, Gro-alpha was chemotactic for T cells expressing CXCR2 in vitro toward both recombinant protein and tumor-derived chemokine. Interestingly we demonstrate, for the first time, that Gro-alpha was able to induce interferon-gamma (IFN-gamma) secretion from transduced T cells, thereby extending our knowledge of other potential functions of CXCR2. This study demonstrates the feasibility of redirecting the migration properties of T cells toward chemokines secreted by tumors.

The potential impact of mouse model selection in preclinical evaluation of cancer immunotherapy.

This commentary provides the authors' perspective on the article "Routes of delivery for CpG and anti-CD137 for the treatment of orthotopic kidney tumors in mice", published in PLoS ONE. It also discusses the caveats of using subcutaneous tumors to model the treatment of human cancers versus orthotopic mouse models that more closely mimic human disease.