Tumor-specific CD8+ T cells expressing interleukin-12 eradicate established cancers in lymphodepleted hosts.
ABSTRACT: T-cell-based immunotherapies can be effective in the treatment of large vascularized tumors, but they rely on adoptive transfer of substantial numbers ( approximately 20 million) of tumor-specific T cells administered together with vaccination and high-dose interleukin (IL)-2. In this study, we report that approximately 10,000 T cells gene-engineered to express a single-chain IL-12 molecule can be therapeutically effective against established tumors in the absence of exogenous IL-2 and vaccine. Although IL-12-engineered cells did not perist long-term in hosts, they exhibited enhanced functionality and were detected in higher numbers intratumorally along with increased numbers of endogenous natural killer and CD8(+) T cells just before regression. Importantly, transferred T cells isolated from tumors stably overproduced supraphysiologic amounts of IL-12, and the therapeutic effect of IL-12 produced within the tumor microenvironment could not be mimicked with high doses of exogenously provided IL-12. Furthermore, antitumor effects could be recapitulated by engineering wild-type open-repertoire splenocytes to express both the single-chain IL-12 and a recombinant tumor-specific T-cell receptor (TCR), but only when individual cells expressed both the TCR and IL-12, indicating that arrested migration of T cells at the tumor site was required for their activities. Successful tumor eradication was dependent on a lymphodepleting preconditioning regimen that reduced the number of intratumoral CD4(+) Foxp3(+) T regulatory cells. Our findings reveal an approach to genetically modify T cells to reduce the cell number needed, eliminate the need for vaccines or systemic IL-2, and improve immunotherapy efficacy based on adoptive transfer of gene-engineered T cells.
Project description:Adoptive therapy with engineered T cells shows promising results in treating patients with malignant disease, but is challenged by incomplete responses and tumor recurrences. Here, we aimed to direct the tumor microenvironment in favor of a successful immune response by local secretion of interleukin (IL-) 12 and IL-18 by sadministered T cells. To this end, we engineered T cells with a melanoma-specific T cell receptor (TCR) and murine IL-12 and/or IL-18 under the control of a nuclear-factor of activated T-cell (NFAT)-sensitive promoter. These T cells produced IL-12 or IL-18, and consequently enhanced levels of IFN?, following exposure to antigen-positive but not negative tumor cells. Adoptive transfer of T cells with a TCR and inducible (i)IL-12 to melanoma-bearing mice resulted in severe, edema-like toxicity that was accompanied by enhanced levels of IFN? and TNF? in blood, and reduced numbers of peripheral TCR transgene-positive T cells. In contrast, transfer of T cells expressing a TCR and iIL-18 was without side effects, enhanced the presence of therapeutic CD8+ T cells within tumors, reduced tumor burden and prolonged survival. Notably, treatment with TCR+iIL-12 but not iIL-18 T cells resulted in enhanced intra-tumoral accumulation of macrophages, which was accompanied by a decreased frequency of therapeutic T cells, in particular of the CD8 subset. In addition, when administered to mice, iIL-18 but not iIL-12 demonstrated a favorable profile of T cell co-stimulatory and inhibitory receptors. In conclusion, we observed that treatment with T cells engineered with a TCR and iIL18 T cells is safe and able to skew the tumor microenvironment in favor of an improved anti-tumor T cell response.
Project description:Abundant IFN-? secretion, potent cytotoxicity, and major histocompatibility complex-independent targeting of a large spectrum of tumors make ?? T cells attractive candidates for cancer immunotherapy. Upon tumor recognition through the T-cell receptor (TCR), NK-receptors, or NKG2D, ?? T cells generate the pro-inflammatory cytokines TNF-? and IFN-?, or granzymes and perforin that mediate cellular apoptosis. Despite these favorable potentials, most clinical trials testing the adoptive transfer of pharmacologically TCR-targeted and expanded ?? T cells resulted in a limited response. Recently, the TCR-independent activation of ?? T cells was identified. However, the modulation of ?? T cell's effector functions solely by cytokines remains to be elucidated. In the present study, we systematically analyzed the impact of IL-2, IL-12, and IL-18 in parallel with TCR stimulation on proliferation, cytokine production, and anti-tumor activity of ?? T cells. Our results demonstrate that IL-12 and IL-18, when combined, constitute the most potent stimulus to enhance anti-tumor activity and induce proliferation and IFN-? production by ?? T cells in the absence of TCR signaling. Intriguingly, stimulation with IL-12 and IL-18 without TCR stimulus induces a comparable degree of anti-tumor activity in ?? T cells to TCR crosslinking by killing tumor cells and driving cancer cells into senescence. These findings approve the use of IL-12/IL-18-stimulated ?? T cells for adoptive cell therapy to boost anti-tumor activity by ?? T cells.
Project description:We explored whether engineering of T cell specificity and effector function improves immunotherapy of solid tumors. Although IL-12 can enhance cancer immunity, a strategy of safe IL-12 delivery without toxicity is currently lacking. We engineered T cells to express IL-12 controlled by the NFAT promoter responsive to TCR stimulation, or by the Tet-On promoter responsive to doxycycline. <i>In vivo</i>, NFAT-engineered T cells caused lethal toxicity, while Tet-engineered T cells were safe in the absence of doxycycline. Combining gene transfer of the melanoma-specific TRP2-TCR with Tet-IL-12 engineering revealed that temporal induction of IL-12 was essential to inhibit the growth of B16F10 melanoma tumors. Induced IL-12 increased the number of tumor-infiltrating T cells and also prevented the down-modulation of the TRP2-TCR and the associated up-regulation of the PD1 marker that was observed in the absence of IL-12. In addition, temporal induction of IL-12 expression also increased the number of plasmacytoid DC in the tumor micro-environment. We show that repeated induction of IL-12 can be used to enhance control of tumor growth without encountering systemic toxicity. The observation that TCR engineering combined with Tet-regulated IL-12 expression can achieve tumor immunity without the side effects that are usually associated with the <i>in vivo</i> use of IL-12 warrants translation of this concept into the clinic.
Project description:The genetic modification of CD8+ T cells using anti-tumor T-cell receptors (TCR) or chimeric antigen receptors is a promising approach for the adoptive cell therapy of patients with cancer. We previously developed a simplified method for the clinical-scale generation of central memory-like (Tcm) CD8+ T cells following transduction with lentivirus encoding anti-tumor TCR and culture in the presence of IL-2. In this study, we compared different cytokines or combinations of IL-2, IL-7, IL-12, IL-15, and IL-21 to expand genetically engineered CD8+ T cells. We demonstrated that specific cytokine combinations IL-12 plus IL-7 or IL-21 for 3 days followed by withdrawal of IL-12 yielded the phenotype of CD62L(high)CD28(high) CD127(high)CD27(high)CCR7(high), which is associated with less-differentiated T cells. Genes associated with stem cells (SOX2, NANOG, OCT4, and LIN28A), were also up-regulated by this cytokine cocktail. Moreover, the use of IL-12 plus IL-7 or IL-21 yielded CD8 T cells showing enhanced persistence in the NOD/SCID/?c-/- mouse model. This defined cytokine combination could also alter highly differentiated TIL from melanoma patients into cells with a less-differentiated phenotype. The methodology that we developed for generating a less-differentiated anti-tumor CD8+ T cells ex vivo may be ideal for the adoptive immunotherapy of cancer.
Project description:Interleukin-12 (IL-12) is an important immunostimulatory cytokine, yet its clinical application has been limited by the systemic toxicity associated with its administration. In this work, we developed a strategy to selectively deliver IL-12 to the tumor environment using genetically engineered lymphocytes. However, peripheral blood lymphocytes (PBLs) transduced with a ?-retroviral vector, which constitutively expressed IL-12, failed to expand in culture due to apoptosis. To circumvent this problem, a vector was designed where IL-12 expression was directed by a composite promoter-containing binding motifs for nuclear factor of activated T-cells (NFAT.hIL12.PA2). The NFAT-responsive promoter was activated to drive IL-12 expression upon the recognition of tumor-specific antigen mediated by a T cell receptor (TCR) that was engineered into the same lymphocytes. We tested the efficacy of the inducible IL-12 vector in vivo in a murine melanoma model. Adoptive transfer of pmel-1 T cells genetically engineered with NFAT-murineIL12 (NFAT.mIL12.PA2) significantly enhanced regression of large established B16 melanoma. Notably, this targeted and controlled IL-12 treatment was without toxicity. Taken together, our results suggest that using the NFAT.hIL12.PA2 vector might be a promising approach to enhance adoptive cancer immunotherapy.
Project description:Mouse CD8(+) T cells conditioned with interleukin (IL)-12 ex vivo mediate the potent regression of established melanoma when transferred into lymphodepleted mice. However, the quantitative and qualitative changes induced by IL-12 in the responding mouse CD8(+) T cells have not been well defined. Moreover, the mechanisms by which IL-12-conditioning impacts human CD8(+) T cells, and how such cells might be expanded prior to infusion into patients is not known. We found that ex vivo IL-12-conditioning of mouse CD8(+) T cells led to a tenfold-100-fold increase in persistence and anti-tumor efficacy upon adoptive transfer into lymphodepleted mice. The enhancing effect of IL-12 was associated with maintenance of functional avidity. Importantly, in the context of ongoing ACT clinical trials, human CD8(+) T cells genetically modified with a tyrosinase-specific T cell receptor (TCR) exhibited significantly enhanced functional activity when conditioned with IL-12 as indicated by heightened granzyme B expression and elevated peptide-specific CD107a degranulation. This effect was sustainable despite the 20 days of in vitro cellular expansion required to expand cells over 1,000-fold allowing adequate cell numbers for administration to cancer patients. Overall, these findings support the efficacy and feasibility of ex vivo IL-12-conditioning of TCR-modified human CD8(+) T cells for adoptive transfer and cancer therapy.
Project description:A key issue in advancing the use of adoptive cell transfer (ACT) of T cell receptor (TCR) engineered lymphocytes for cancer therapy is demonstrating how TCR transgenic cells repopulate lymphopenic hosts and target tumors in an antigen-specific fashion. ACT of splenocytes from fully immunocompetent HLA-A2.1/K(b) mice transduced with a chimeric murine/human TCR specific for tyrosinase, together with lymphodepletion conditioning, dendritic cell (DC)-based vaccination, and high-dose interleukin-2 (IL-2), had profound antitumor activity against large established MHC- and antigen-matched tumors. Genetic labeling with bioluminescence imaging (BLI) and positron emitting tomography (PET) reporter genes allowed visualization of the distribution and antigen-specific tumor homing of TCR transgenic T cells, with trafficking correlated with antitumor efficacy. After an initial brief stage of systemic distribution, TCR-redirected and genetically labeled T cells demonstrated an early pattern of specific distribution to antigen-matched tumors and locoregional lymph nodes, followed by a more promiscuous distribution 1 wk later with additional accumulation in antigen-mismatched tumors. This approach of TCR engineering and molecular imaging reporter gene labeling is directly translatable to humans and provides useful information on how to clinically develop this mode of therapy.
Project description:A major factor hindering the exploration of adoptive immunotherapy in preclinical settings is the limited availability of tumor-reactive human T cells. Here we developed a humanized mouse model that permits large-scale production of human T cells expressing the engineered melanoma antigen MART-1-specific TCR. Humanized mice, made by transplantation of human fetal thymic tissue and CD34+ cells virally-transduced with HLA class I-restricted melanoma antigen (MART-1)-specific TCR gene, showed efficient development of MART-1-TCR+ human T cells with predominantly CD8+ cells. Importantly, MART-1-TCR+CD8+ T cells developing in these mice were capable of mounting antigen-specific responses in vivo, as evidenced by their proliferation, phenotypic conversion and IFN-? production following MART-1 peptide immunization. Moreover, these MART-1-TCR+CD8+ T cells mediated efficient killing of melanoma cells in an HLA/antigen-dependent manner. Adoptive transfer of in vitro expanded MART-1-TCR+CD8+ T cells induced potent antitumor responses that were further enhanced by IL-15 treatment in melanoma-bearing recipients. Finally, a short incubation of MART-1-specific T cells with rapamycin acted synergistically with IL-15, leading to significantly improved tumor-free survival in recipients with metastatic melanoma. These data demonstrate the practicality of using humanized mice to produce potentially unlimited source of tumor-specific human T cells for experimental and preclinical exploration of cancer immunotherapy. This study also suggests that pretreatment of tumor-reactive T cells with rapamycin in combination with IL-15 administration may be a novel strategy to improve the efficacy of adoptive T cell therapy.
Project description:Naive CD8 T cells proliferate in response to TCR and CD28 signals, but require IL-12 or type I IFN to survive and develop optimal effector functions. Although murine CTL generated in vitro in response to IL-12 or IFN-? had comparable effector functions, IL-12-stimulated cells were significantly more effective in controlling tumor in an adoptive immunotherapy model. They maintained high numbers and function, whereas IFN-?-stimulated cells declined in number and became exhausted. Consistent with this, IFN-?-stimulated cells in the tumor expressed higher levels of programmed death 1 (PD-1) inhibitory receptor than did IL-12-stimulated cells. When blocking Ab specific for the PD-L1 ligand of PD-1 was administered, the efficacy of IFN-?-stimulated CTL became comparable with that of IL-12-stimulated cells. Thus, IL-12 and IFN-? differentially program CD8 T cells to re-express distinct levels of PD-1 upon re-encountering Ag, resulting in IL-12-stimulated cells being less susceptible to exhaustion in the face of sustained tumor Ag.
Project description:In the past two decades, human gene transfer research has been translated from a laboratory technology to clinical evaluation. The success of adoptive transfer of tumor-reactive lymphocytes to treat the patients with metastatic melanoma has led to new strategies to redirect normal T cells to recognize tumor antigens by genetic engineering with tumor antigen-specific T cell receptor (TCR) genes. This new strategy can generate large numbers of defined antigen-specific cells for therapeutic application. Much progress has been made to TCR gene transfer systems by optimizing gene expression and gene transfer protocols. Vector and protein modifications have enabled excellent expression of introduced TCR chains in human lymphocytes with reduced mis-pairing between the introduced and endogenous TCR chains. Initial clinical studies have demonstrated that TCR gene-engineered T cells could mediate tumor regression in vivo. In this review, we discuss the progress and prospects of TCR gene-engineered T cells as a therapeutic strategy for treating patients with melanoma and other cancers.