Boosting immune surveillance by low-dose PI3K inhibitor facilitates early intervention of breast cancer

Prevention of estrogen receptor-negative (ER-) breast cancer is an unmet challenge, although tamoxifen and aromatase inhibitors can successfully decrease the incidence of ER-positive (ER+) breast cancer. PI3K pathway activation has been detected in tamoxifen-resistant ER- breast lesions of patients. Here, we further ratified that the PI3K pathway is significantly activated in premalignant ER- breast lesions compared with paired normal tissues of patients, which prompted our assessment of targeting PI3K on inhibition of ER- mammary tumor initiation and progression. Both genetic knockdown of PIK3CA or intervention with low-doses of a PI3K inhibitor (GDC-0941) prevented the dysplasia phenotype of semi-transformed human ER- mammary epithelial cells in 3-dimensional culture in vitro. Importantly, low-dose GDC-0941 treatment significantly delayed mammary tumor initiation in the MMTV-neu mouse model without exhibiting discernable adverse effects. Interestingly, increased CD8⁺/GZMB⁺ T-cells were detected in mammary tissue after GDC-0941 treatment, suggesting enhanced immune surveillance. Mechanistically, elevated expression of potent T-cell chemo-attractants, including CCL5 and CXCL10, were detected both in vitro and in vivo after GDC-0941 treatment. Furthermore, inhibition of PI3K significantly increased T-cell recruitment in a CCL5/CXCL10-dependent manner. In human ER- breast cancer, PI3K activation is correlated with significantly reduced CCL5, CXCL10 and CD8A expression, suggesting that the decreased CD8⁺ T-cell recruitment and escape of immune surveillance may contribute to ER- breast cancer development. In summary, our study indicates that low-dose PI3K inhibitor treatment may intervene early stage ER- breast cancer development by enhancing immune surveillance via CCL5/CXCL10.     

EBV-positive pyothorax-associated lymphoma expresses CXCL9 and CXCL10 chemokines that attract cytotoxic lymphocytes via CXCR3

Epstein–Barr virus (EBV)-positive diffuse large B-cell lymphoma associated with chronic inflammation (DLBCL-CI) develops in the setting of long-standing inflammation. This type of lymphoma may have specific expression profiles of chemokines involved in the pathogenesis of DLBCL-CI. EBV-positive pyothorax-associated lymphoma (PAL) is a prototype of DLBCL-CI and represents a valuable model for the study of this disease category. Using a panel of PAL cell lines, we found that PAL cells expressed and secreted C–X–C motif chemokine ligands 9 and 10 (CXCL9 and CXCL10), the ligands of CXCR3, in contrast to EBV-negative DLBCL cell lines, which did not. Culture supernatants from PAL cell lines attracted CXCR3-expressing CD4⁺ T cells, CD8⁺ T cells, and CD56⁺ natural killer cells from human peripheral blood mononuclear cells. PAL cells injected into mice also attracted CXCR3-positive cytotoxic lymphocytes that expressed interferon-γ. The expression of CXCL9 and CXCL10 was detected in PAL tumor biopsy samples from patients, and CXCR3-positive lymphocytes were abundant in the tissue samples. Collectively, these findings suggest that CXCL9 and CXCL10 are produced by PAL cells and can elicit cytotoxic responses via CXCR3. This chemokine system is also likely to contribute to tissue necrosis, which is a signature histological feature of DLBCL-CI. Further studies are warranted to determine whether the CXCL9–CXCL10/CXCR3 axis exerts antitumor effects in DLBCL-CI.     

CD4+ T cell exhaustion leads to adoptive transfer therapy failure which can be prevented by immune checkpoint blockade

Cytotoxic CD8⁺ T cell exhaustion is one of the mechanisms underlying the tumor immune escape. The paradigm-shifting immune checkpoint therapy can mitigate CD8⁺ T lymphocyte exhaustion, reinvigorate the anticancer immunity, and achieve durable tumor regression for some patients. Emerging evidence indicates that CD4⁺ T lymphocytes also have a critical role in anticancer immunity, either by directly applying cytotoxicity toward cancer cells or as a helper to augment CD8⁺ T cell cytotoxicity. Whether anticancer CD4⁺ T lymphocytes undergo exhaustion during immunotherapy of solid tumors remains unknown. Here we report that melanoma antigen TRP-1/gp75-specific CD4⁺ T lymphocytes exhibit an exhaustion phenotype after being adoptively transferred into mice bearing large subcutaneous melanoma. Exhaustion of these CD4⁺ T lymphocytes is accompanied with reduced cytokine release and increased expression of inhibitory receptors, resulting in loss of tumor control. Importantly, we demonstrate that PD-L1 immune checkpoint blockade can prevent exhaustion, induce proliferation of the CD4⁺ T lymphocytes, and consequently prevent tumor recurrence. Therefore, when encountering an excessive amount of tumor antigens, tumor-reactive CD4⁺ T lymphocytes also enter the exhaustion state, which can be prevented by immune checkpoint blockade. Our results highlight the importance of tumor-specific CD4⁺ T lymphocytes in antitumor immunity and suggest that the current immune checkpoint blockade therapy may achieve durable anticancer efficacy by rejuvenating both tumor antigen-specific CD8⁺ T lymphocytes and CD4⁺ T lymphocytes.     

Enhancement of adoptive T cell transfer with single low dose pretreatment of doxorubicin or paclitaxel in mice

Ex vivo expansion of CD8⁺ T-cells has been a hindrance for the success of adoptive T cell transfer in clinic. Currently, preconditioning with chemotherapy is used to modulate the patient immunity before ACT, however, the tumor microenvironment beneficial for transferring T cells may also be damaged. Here preconditioning with single low dose of doxorubicin or paclitaxel combined with fewer CD8⁺ T-cells was investigated to verify whether the same therapeutic efficacy of ACT could be achieved. An E.G7/OT1 animal model that involved adoptive transfer of OVA-specific CD8⁺ T-cells transduced with a granzyme B promoter-driven firefly luciferase and tomato fluorescent fusion reporter gene was used to evaluate this strategy. The result showed that CD8⁺ T-cells were activated and sustained longer in mice pretreated with one low-dose Dox or Tax. Enhanced therapeutic efficacy was found in Dox or Tax combined with 2×10⁶ CD8⁺ T-cells and achieved the same level of tumor growth inhibition as that of 5×10⁶ CD8⁺ T-cells group. Notably, reduced numbers of Tregs and myeloid derived suppressor cells were shown in combination groups. By contrast, the number of tumor-infiltrating cytotoxic T lymphocytes and IL-12 were increased. The NF-κB activity and immunosuppressive factors such as TGF-β, IDO, CCL2, VEGF, CCL22, COX-2 and IL-10 were suppressed. This study demonstrates that preconditioning with single low dose Dox or Tax and combined with two fifth of the original CD8⁺ T-cells could improve the tumor microenvironment via suppression of NF-κB and its related immunosuppressors, and activate more CD8⁺ T-cells which also stay longer.     

CD133+ ovarian cancer stem-like cells promote non-stem cancer cell metastasis via CCL5 induced epithelial-mesenchymal transition

Cancer stem cells (CSCs, also called cancer stem-like cells, CSLCs) can function as “seed cells” for tumor recurrence and metastasis. Here, we report that, in the presence of CD133⁺ ovarian CSLCs, CD133⁻ non-CSLCs can undergo an epithelial-mesenchymal transition (EMT)-like process and display enhanced metastatic capacity in vitro and in vivo. Highly elevated expression of chemokine (C-C motif) ligand 5 (CCL5) and its receptors chemokine (C-C motif) receptor (CCR) 1/3/5 are observed in clinical and murine metastatic tumor tissues from epithelial ovarian carcinomas. Mechanistically, paracrine CCL5 from ovarian CSLCs activates the NF-κB signaling pathway in ovarian non-CSLCs via binding CCR1/3/5, thereby inducing EMT and tumor invasion. Taken together, our results redefine the metastatic potential of non-stem cancer cells and provide evidence that targeting the CCL5:CCR1/3/5-NF-κB pathway could be an effective strategy to prevent ovarian cancer metastasis.     

NEDD9 promotes cancer stemness by recruiting myeloid-derived suppressor cells via CXCL8 in esophageal squamous cell carcinoma

Objective:Esophageal squamous cell carcinoma (ESCC) has high morbidity and mortality rates worldwide. Cancer stem cells (CSCs) may cause tumor initiation, metastasis, and recurrence and are also responsible for chemotherapy and radiotherapy failures. Myeloid-derived suppressor cells (MDSCs), in contrast, are known to be involved in mediating immunosuppression. Here, we aimed to investigate the mechanisms of interaction of CSCs and MDSCs in the tumor microenvironment.Methods:ESCC tissues and cell lines were evaluated. Neural precursor cell expressed, developmentally downregulated 9 (NEDD9) was knocked down and overexpressed by lentiviral transfection. Quantitative PCR, Western blot, immunohistochemistry, cell invasion, flow cytometry, cell sorting, multiplex chemokine profiling, and tumor growth analyses were performed.Results:Microarray analysis revealed 10 upregulated genes in esophageal CSCs. Only NEDD9 was upregulated in CSCs using the sphere-forming method. NEDD9 expression was correlated with tumor invasion (P = 0.0218), differentiation (P = 0.0153), and poor prognosis (P = 0.0373). Additionally, NEDD9 was required to maintain the stem-like phenotype. Screening of chemokine expression in ESCC cells with NEDD9 overexpression and knockdown showed that NEDD9 regulated C-X-C motif chemokine ligand 8 (CXCL8) expression via the ERK pathway. CXCL8 mediated the recruitment of MDSCs induced by NEDD9 in vitro and in vivo. MDSCs promoted the stemness of ESCC cells through NEDD9 via the Notch pathway.Conclusions:As a marker of ESCC, NEDD9 maintained the stemness of ESCC cells and regulated CXCL8 through the ERK pathway to recruit MDSCs into the tumor, suggesting NEDD9 as a therapeutic target and novel prognostic marker for ESCC.     

Perivascular expression of CXCL9 and CXCL12 in primary central nervous system lymphoma: T‐cell infiltration and positioning of malignant B cells

Primary central nervous system lymphomas (PCNSL) are aggressive malignancies confined to the CNS, mostly of diffuse large B‐cell histotype. Despite improved understanding of the malignant B cells, little is known on the tumor microenvironment and on the response of the adaptive immunity against PCNSL. We investigated the phenotype of tumor infiltrating lymphocytes (TILs), and the expression of chemokines that could affect malignant B cells and trafficking of TILs. TILs and chemokine expression were evaluated by immunohistochemistry and in situ hybridization. Furthermore, we performed in vitro migration assays to analyze the migratory capacity of lymphocytes and malignant B cells toward chemokines and chemokine heterocomplexes. We show in 22 cases of PCNSL from immunocompetent patients that CD8⁺ T cells represent the majority of TILs in the tumor mass. They tend to accumulate in perivascular areas, show Granzyme B expression and proliferate in situ. Their localization and density correlates with the expression of the inflammatory chemokine CXCL9, which is transcribed and translated by perivascular macrophages and pericytes in the perivascular microenvironment. Moreover, CXCL9 and CXCL12 are coexpressed on the tumor vasculature and form heterocomplexes. In the presence of CXCL9, CXCL12‐induced migration is enhanced not only on CXCR4⁺/CXCR3⁺/CD8⁺ T cells but also on CXCR4⁺/CXCR3^? malignant B cells. These findings indicate the presence of a strong chemoattractant stimulus in the perivascular microenvironment, which might serve as regulator for the recruitment of TILs and for the angiocentric positioning of malignant B cells in the perivascular cuff.     

Evidence for the antagonistic form of CXC‐motif chemokine CXCL10 in serous epithelial ovarian tumours

Patients with high‐grade, serous epithelial ovarian carcinoma (HGSOC) are generally diagnosed with extensive peritoneal metastases, and exhibit 5‐year survival rates <30%. A subset of these tumours, defined as “immunoreactive,” overexpress mRNA encoding the T‐cell‐recruiting chemokine CXCL10 (10‐kDa interferon gamma‐induced protein; C‐X‐C motif chemokine 10). Tumour‐infiltrating CD4⁺CD8⁺ T‐cells are a well‐documented, positive prognostic indicator for HGSOC patients; paradoxically, however, patients diagnosed with HGSOC (overexpressing CXCL10 and therefore theorised to recruit T‐cells) typically exhibit poor survival. Recently, an “antagonistic” CXCL10 variant was identified that inhibited leucocyte recruitment to inflamed liver in vivo (Casrouge et al., J Clin Invest 2011;121:308–17). We hypothesised that “immunoreactive” HGSOC might also express antagonistic CXCL10, interfering with leucocyte recruitment and contributing to poor patient prognosis. CXCL10 expression was analysed in HGSOC tissues grouped according to pathology, grade and FIGO stage at diagnosis, and its localisation and association with T‐cells established by immunohistochemical staining in tissue microarrays. CXCL10 expression was increased in a subset of serous epithelial tumour samples; however, it did not correlate well with CD45‐positive tumour infiltrate. Immunoprecipitation and de novo sequence analysis of CXCL10 identified the N‐terminally cleaved, “antagonistic” variant of CXCL10 specifically in malignant tumours, and not in benign ovarian disease. The data demonstrate the presence of the antagonistic form of CXCL10 in HGSOC for the first time, and provide a partial explanation for reduced leucocyte infiltration observed in these tumours. We suggest that CXCL10 cleavage and subsequent antagonism of immune cell recruitment may be a feature of the “immunoreactive” HGSOC subtype, leading to early impairment of the immune response and subsequently worsening patient prognosis.     

共刺激分子B7-H3在人食管鳞癌中的表达及临床意义

目的 分析人食管鳞癌组织中B7-H3分子的表达与患者临床病理因素以及术后生存时间之间的关系。方法 采用免疫组织化学法检测82例人食管癌组织、对应癌旁正常食管组织及食管鳞状上皮不典型增生组织中B7-H3分子的表达以及CD8+T淋巴细胞的浸润程度。结果 食管癌组织中B7-H3蛋白的阳性表达率为98.8%(81/82),而B7-H3在癌旁及鳞状上皮不典型增生组织中几乎不表达。B7-H3的表达与患者年龄、肿瘤浸润深度及TNM分期相关,差异有统计学意义（P<0.05）,与肿瘤组织中CD8+T淋巴细胞浸润程度呈负相关(P<0.05),与患者预后呈负相关（P<0.05）。结论 B7-H3在食管癌中过表达,和肿瘤的进展密切相关。食管癌中B7-H3分子的表达可能参与了抑制食管癌组织内CD8+T细胞功能,促使肿瘤细胞逃避免疫监视,提示B7-H3在食管癌诊断、判断预后及靶向治疗中具有潜在的临床应用价值。     

Regulatory T cells and the PD-L1/PD-1 pathway mediate immune suppression in malignant human brain tumors

The brain is a specialized immune site representing a unique tumor microenvironment. The availability of fresh brain tumor material for ex vivo analysis is often limited because large parts of many brain tumors are resected using ultrasonic aspiration. We analyzed ultrasonic tumor aspirates as a biosource to study immune suppressive mechanisms in 83 human brain tumors. Lymphocyte infiltrates in brain tumor tissues and ultrasonic aspirates were comparable with respect to lymphocyte content and viability. Applying ultrasonic aspirates, we detected massive infiltration of CD4⁺FoxP3⁺CD25^high CD127^low regulatory T cells (Tregs) in glioblastomas (n = 29) and metastatic brain tumors (n = 20). No Treg accumulation was observed in benign tumors such as meningiomas (n = 10) and pituitary adenomas (n = 5). A significant Treg increase in blood was seen only in patients with metastatic brain tumors. Tregs in high-grade tumors exhibited an activated phenotype as indicated by decreased proliferation and elevated CTLA-4 and FoxP3 expression relative to blood Tregs. Functional analysis showed that the tumor-derived Tregs efficiently suppressed cytokine secretion and proliferation of autologous intratumoral lymphocytes. Most tumor-infiltrating Tregs were localized in close proximity to effector T cells, as visualized by immunohistochemistry. Furthermore, 61% of the malignant brain tumors expressed programmed death ligand-1 (PD-L1), while the inhibitory PD-1 receptor was expressed on CD4⁺ effector cells present in 26% of tumors. In conclusion, using ultrasonic tumor aspirates as a biosource we identified Tregs and the PD-L1/PD-1 pathway as immune suppressive mechanisms in malignant but not benign human brain tumors.     

Programmed cell death ligand 1 disruption by clustered regularly interspaced short palindromic repeats/Cas9‐genome editing promotes antitumor immunity and suppresses ovarian cancer progression

Programmed cell death ligand 1 (PD‐L1) on tumor cells suppresses anti‐tumor immunity and has an unfavorable prognostic impact in ovarian cancer patients. We herein report the pathophysiological and therapeutic impacts of PD‐L1 disruption in ovarian cancer. PD‐L1 was genetically disrupted in the murine ovarian cancer cell line ID8 using clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9‐mediated genome editing. PD‐L1 knockout (KO) and control ovarian cancer cells were intraperitoneally inoculated into syngeneic mice, and survival and tumor dissemination were evaluated. Survival times were significantly longer in the PD‐L1‐KO ID8‐inoculated groups than in their control groups, and its therapeutic benefit was enhanced in combination with the cisplatin treatment. Tumor weights and ascites volumes were significantly lower in the PD‐L1‐KO ID8 groups than in their control groups. Immunohistochemical and immunofluorescence analyses showed that intratumoral CD4⁺ T cells, CD8⁺ T cells, NK cells and CD11c⁺ M1 macrophages were significantly increased, whereas regulatory T cells were significantly decreased in the PD‐L1‐KO ID8 groups compared with those in their control groups. The intratumoral mRNA expression of interferon‐γ, tumor‐necrosis factor‐α, interleukin (IL)‐2, IL‐12a, CXCL9 and CXCL10 was significantly stronger, while that of IL‐10, vascular endothelial growth factor, CXCL1 and CXCL2 was significantly weaker in the PD‐L1‐KO ID8 groups. These results indicate that CRISPR/Cas9‐mediated PD‐L1 disruption on tumor cells promotes anti‐tumor immunity by increasing tumor‐infiltrating lymphocytes and modulating cytokine/chemokine profiles within the tumor microenvironment, thereby suppressing ovarian cancer progression. These results suggest that PD‐L1‐targeted therapy by genome editing may be a novel therapeutic strategy for ovarian cancer.     

CD40 controls CXCR5-induced recruitment of myeloid-derived suppressor cells to gastric cancer

To explore the mechanisms of MDSC trafficking and accumulation during tumor progression. In this study, we report significant CD40 upregulation in tumor-infiltrating MDSC when compared with splenic MDSC. Microarray analyses comparing CD40^high and CD40^low MDSC revealed 1872 differentially expressed genes, including CD83, CXCR5, BTLA, CXCL9, TLR1, FLT3, NOD2 and CXCL10. In vivo experiments comparing wild-type (WT) and CD40 knockout (KO) mice demonstrated that CD40 critically regulates CXCR5 expression. Consistently, the transwell analysis confirmed the essential role of CXCR5-CXCL13 crosstalk in the migration of CD40⁺ MDSC toward gastric cancer. Furthermore, more MDSC accumulated in the gastric cancers of WT mice when compared with KO mice, and the WT tumors mostly contained CD40⁺ cells. Functionally, tumors grew faster in WT than KO mice. In conclusion, we demonstrate that CD40 expression upregulates the chemokine receptor CXCR5 and promotes MDSC migration toward and accumulation within cancer. Therefore, this study provides preliminary evidence that CD40 may stimulate tumor growth by enabling immune evasion via MDSC recruitment and inhibition of T cell expansion.     

Numbers and cytotoxicities of CD3+CD56+ T lymphocytes in peripheral blood of patients with acute myeloid leukemia and acute lymphocytic leukemia

Recent reports have highlighted the role of cellular immunity in anti-tumor defenses. T lymphocytes are known to play important part in anti-cancer immunity. The number and function of T lymphocytes are altered in chronic leukemia patients. CD3⁺CD56⁺ T lymphocytes have also been found to be abnormal in cancer patients. We therefore investigated changes in the number and cytotoxicity of CD3⁺CD56⁺ T lymphocytes in the peripheral blood of acute leukemia (AL) patients (excluding acute promyelocytic leukemia), to improve our understanding of the role of this T lymphocyte subset. We analyzed CD3⁺CD56⁺ T lymphocyte numbers and cytotoxicities in healthy controls, AL patients, and AL patients with complete remission. Lymphocyte counts were performed in peripheral blood and flow cytometry was used to determine cell numbers and cytotoxicities. The absolute number of CD3⁺CD56⁺ T lymphocytes was increased in AL patients (including acute myeloid [AML] and acute lymphocytic leukemia [ALL]) compared with healthy controls (P < 0.05), but their functioning was significantly reduced (P < 0.05). The number of CD3⁺CD56⁺ T lymphocytes in AML and ALL patients who achieved remission following chemotherapy was close to healthy controls (P > 0.05), but their functioning was still significantly reduced (P < 0.05). In addition, the number of CD3⁺CD56⁺ T lymphocytes increased significantly in AML patients with increased peripheral blood white blood cell (WBC) counts, and in ALL patients without increased WBCs. These results suggest that cellular immunity may respond to AML and ALL, but that lymphocyte cytotoxicity remains impaired. Dysfunction of CD3⁺CD56⁺ T lymphocytes in AML and ALL patients may contribute to the failure of the host immune response against leukemic blasts.     

CCL3 and CCL20-recruited dendritic cells modified by melanoma antigen gene-1 induce anti-tumor immunity against gastric cancer ex vivo and in vivo

Background

To investigate whether dendritic cell (DC) precursors, recruited by injection of chemokine ligand 3 (CCL3) and CCL20, induce anti-tumor immunity against gastric cancer induced by a DC vaccine expressing melanoma antigen gene-1 (MAGE-1) ex vivo and in vivo.

Methods

B6 mice were injected with CCL3 and CCL20 via the tail vein. Freshly isolated F4/80^-B220^-CD11c⁺ cells cultured with cytokines were analyzed by phenotype analysis and mixed lymphocyte reaction (MLR). For adenoviral (Ad)-mediated gene transduction, cultured F4/80^-B220^-CD11c⁺ cells were incubated with Ad-MAGE-1. Vaccination of stimulated DC induced T lymphocytes. The killing effect of these T cells against gastric carcinoma cells was assayed by MTT. INF-γ production was determined with an INF-γ ELISA kit. In the solid tumor and metastases model, DC-based vaccines were used for immunization after challenge with MFC cells. Tumor size, survival of mice, and number of pulmonary metastatic foci were used to assess the therapeutic effect of DC vaccines.

Results

F4/80^-B220^-CD11c⁺ cell numbers increased after CCL3 and CCL20 injection. Freshly isolated F4/80^-B220^-CD11c⁺ cells cultured with cytokines were phenotyically identical to typical DC and gained the capacity to stimulate allogeneic T cells. These DCs were transduced with Ad-MAGE-1, which were prepared for DC vaccines expressing tumor antigen. T lymphocytes stimulated by DCs transduced with Ad-MAGE-1 exhibited specific killing effects on gastric carcinoma cells and produced high levels of INF-γ ex vivo. In vivo, tumor sizes of the experimental group were much smaller than both the positive control group and the negative control groups (P < 0.05). Kaplan-Meier survival curves showed that survival of the experimental group mice was significantly longer than the control groups (P < 0.05). In addition, MAGE-1-transduced DCs were also a therapeutic benefit on an established metastatic tumor, resulting in a tremendous decrease in the number of pulmonary metastatic foci.

Conclusions

CCL3 and CCL20-recruited DCs modified by adenovirus-trasnsduced, tumor-associated antigen, MAGE-1, can stimulate anti-tumor immunity specific to gastric cancer ex vivo and in vivo. This system may prove to be an efficient strategy for anti-tumor immunotherapy.     

B7.1 gene transduction of human renal-cell-carcinoma cell lines restores the proliferative response and cytotoxic function of allogeneic T cells

Renal-cell-carcinoma is one of the human tumors for which the immune response may control the growth of tumor cells. Conversely, T cells infiltrating this tumor have been reported to be impaired in proliferative and effector functions. Complete activation of T cells requires 2 signaling events, one through the antigen-specific receptor and one through the B7 ligand, CD28. In the present study, we first showed the absence of B7.1 expression on RCC tumors and cell lines, and the low proliferative response of allogeneic T cells upon stimulation with these cells. Transduction of the human gene for B7.1 rendered these cells potent stimulators of allogeneic mixed lymphocyte response. Furthermore, stimulation of purified CD4⁺ and CD8⁺ T-cell populations showed that transduced cell lines preferentially induced the proliferation of CD8⁺ T cells. Finally, mixed lymphocyte cultures in the presence of the B7.1⁺ cell lines led to the generation of cytotoxic T lymphocytes able to specifically recognize both the transduced stimulator and the parental cell line. We thus demonstrate that B7.1 expression on human tumor cell lines is capable of inducing MHC-class-1-dependent proliferation and differentiation into cytotoxic effectors of allogeneic CD8⁺ T cells. The lack of B7 expression on RCC cell lines is responsible for their failure to activate allogeneic T cells, a result which strongly suggests that the same mechanism may be implied in the impaired tumor-cell presentation to autologous T cells. © 1996 Wiley-Liss, Inc.     

Human effector T cells derived from central memory cells rather than CD8T cells modified by tumor-specific TCR gene transfer possess superior traits for adoptive immunotherapy

Adoptive cell therapy provides an attractive treatment of cancer, and our expanding capacity to target tumor antigens is driven by genetically engineered human T lymphocytes that express genes encoding tumor-specific T cell receptors (TCRs). The intrinsic properties of cultured T cells used for therapy were reported to have tremendous influences on their persistence and antitumor efficacy in vivo. In this study, we isolated CD8⁺ central memory T cells from peripheral blood lymphocytes of healthy donors, and then transferred with the gene encoding TCR specific for tumor antigen using recombinant adenovirus vector Ad5F35-TRAV-TRBV. We found effector T cells derived from central memory T cells improved cell viability, maintained certain level of CD62L expression, and reacquired the CD62L⁺CD44^high phenotype of central memory T cells after effector T cells differentiation. We then compared the antitumor reactivity of central memory T cells and CD8⁺T cells after TCR gene transferred. The results indicated that tumor-specific TCR gene being transferred to central memory T cells effectively increased the specific killing of antigen positive tumor cells and the expression of cytolytic granule protein. Furthermore, TCR gene transferred central memory T cells were more effective than TCR gene transferred CD8⁺T cells in CTL activity and effector cytokine secretion. These results implicated that isolating central memory T cells rather than CD8⁺T cells for insertion of gene encoding tumor-specific TCR may provide a superior tumor-reactive T cell population for adoptive transfer.