Expression of tumor antigens within an oncolytic virus enhances the anti-tumor T cell response.

Although patients benefit from immune checkpoint inhibition (ICI) therapy in a broad variety of tumors, resistance may arise from immune suppressive tumor microenvironments (TME), which is particularly true of hepatocellular carcinoma (HCC). Since oncolytic viruses (OV) can generate a highly immune-infiltrated, inflammatory TME, OVs could potentially restore ICI responsiveness via recruitment, priming, and activation of anti-tumor T cells. Here we find that on the contrary, an oncolytic vesicular stomatitis virus, expressing interferon-ß (VSV-IFNß), antagonizes the effect of anti-PD-L1 therapy in a partially anti-PD-L1-responsive model of HCC. Cytometry by Time of Flight shows that VSV-IFNß expands dominant anti-viral effector CD8 T cells with concomitant relative disappearance of anti-tumor T cell populations, which are the target of anti-PD-L1. However, by expressing a range of HCC tumor antigens within VSV, combination OV and anti-PD-L1 therapeutic benefit could be restored. Our data provide a cautionary message for the use of highly immunogenic viruses as tumor-specific immune-therapeutics by showing that dominant anti-viral T cell responses can inhibit sub-dominant anti-tumor T cell responses. However, through encoding tumor antigens within the virus, oncolytic virotherapy can generate anti-tumor T cell populations upon which immune checkpoint blockade can effectively work.

Chimerization of the Anti-Viral CD8+ T Cell Response with A Broad Anti-Tumor T Cell Response Reverses Inhibition of Checkpoint Blockade Therapy by Oncolytic Virotherapy.

Although immune checkpoint inhibition (ICI) has produced profound survival benefits in a broad variety of tumors, a proportion of patients do not respond. Treatment failure is in part due to immune suppressive tumor microenvironments (TME), which is particularly true of hepatocellular carcinoma (HCC). Since oncolytic viruses (OV) can generate a highly immune-infiltrated, inflammatory TME, we developed a vesicular stomatitis virus expressing interferon-ß (VSV-IFNß) as a viro-immunotherapy against HCC. Since HCC standard of care atezolizumab/bevacizumab incorporates ICI, we tested the hypothesis that pro-inflammatory VSV-IFNß would recruit, prime, and activate anti-tumor T cells, whose activity anti-PD-L1 ICI would potentiate. However, in a partially anti-PD-L1-responsive model of HCC, addition of VSV-IFNß abolished anti-PD-L1 therapy. Cytometry by Time of Flight showed that VSV-IFNß expanded dominant anti-viral effector CD8 T cells with concomitant, relative disappearance of anti-tumor T cell populations which are the target of anti-PD-L1. However, by expressing a range of HCC tumor antigens within VSV, the potent anti-viral response became amalgamated with an anti-tumor T cell response generating highly significant cures compared to anti-PD-L1 ICI alone. Our data provide a cautionary message for the use of highly immunogenic viruses as tumor-specific immune-therapeutics by showing that dominant anti-viral T cell responses can inhibit sub-dominant anti-tumor T cell responses. However, by chimerizing anti-viral and anti-tumor T cell responses through encoding tumor antigens within the virus, oncolytic virotherapy can be purposed for very effective immune driven tumor clearance and can generate anti-tumor T cell populations upon which immune checkpoint blockade can effectively work.

Anti-PD-L1 × anti-CD3 bispecific T-cell engager-armed T cells can overcome immunosuppression and redirect T cells to kill breast cancer cells expressing PD-L1.

T cell-based immunotherapy has transformed cancer treatment. Nonetheless, T cell antitumor activity can be inhibited by an immune checkpoint molecule expressed on cancer cells, program death ligand 1 (PD-L1), which interacts with the PD-1 on T cells. We generated αPD-L1 × αCD3 bispecific T-cell engager-armed T cells (BATs) to prevent PD-L1/PD-1 interaction and hence to redirect T cells to kill cancer cells. αPD-L1 × αCD3 bispecific T-cell engagers (BTEs) were produced from Chinese hamster ovary (CHO) cells to arm human primary T cells. Flow cytometry was used to investigate BTE binding to BATs. The cytotoxicity of BATs against PD-L1-expressing breast cancer (BC) cell lines was assessed in 2-dimensional (2D) and 3-dimensional (3D) culture models. The binding stability of BTE on BATs and their efficacy after cryopreservation were also examined. The CHO cell BTE expression yield was 3.34 mg/ml. The binding ability on T cells reached 91.02 ± 4.2 %. BATs specifically lysed PD-L1-expressing BC cells, with 56.4 ± 15.3 % HCC70 cells and 70.67 ± 15.6 % MDA-MB-231 cells lysed at a 10:1 effector-to-target ratio. BATs showed slight, nonsignificant lysis of PD-L1-negative BC cells, MCF-7, and T47D. Moreover, BATs significantly disrupted MDA-MB-231 3D spheroids expressing PD-L1 after 48 and 72 h of coculture. Cryopreserved BATs maintained BTE binding stability, cell viability, and anticancer activity, comparable to fresh BATs. αPD-L1 × αCD3 BATs induced the cytolysis of PD-L1-expressing BC cells in 2D and 3D coculture assays. BATs can be prepared and preserved, facilitating their use and transportation. This study demonstrates the potential of αPD-L1 × αCD3 BATs in treating cancers with positive PD-L1 expression.

Cytotoxic activity of anti-mucin 1 chimeric antigen receptor T cells expressing PD-1-CD28 switch receptor against cholangiocarcinoma cells.

BACKGROUND AIMS: Cholangiocarcinoma (CCA) is a lethal bile-duct cancer that is difficult to treat by current standard procedures. This drawback has prompted us to develop adoptive T-cell therapy for CCA, which requires an appropriate target antigen for binding of chimeric antigen receptor (CAR) T cells. Mucin 1 (MUC1), an overexpressed protein in CCA cells, is a potential target antigen for the CAR T-cell development. However, MUC1 overexpression also is associated with the upregulation of programmed death-ligand 1 (PD-L1), an immune checkpoint protein that prohibits anti-tumor functions of T cells, probably causing poor overall survival of patients with CCA. METHODS: To overcome this problem, we developed anti-MUC1-CAR T cells containing PD-1-CD28 switch receptor (SR), namely αM.CAR/SR T cells, to target MUC1 and switch on the inhibitory signal of PD-1/PD-L1 interaction to activate CD28 signaling. Our lentiviral construct contains the sequences that encode anti-MUC1-single chain variable fragment, CD137 and CD3ζ, linked with P2A, PD-1 and CD28. RESULTS: Initially, the upregulations of MUC1 and PD-L1 proteins were confirmed in CCA cell lines. αM.CAR and SR were co-expressed in 53.53 ± 13.89% of transduced T cells, mainly CD8+ T cells (85.7 ± 0.75%, P<0.0001) with the effector memory phenotype (59.22 ± 16.31%, P < 0.01). αM.CAR/SR T cells produced high levels of intracellular tumor necrosis factor-α and interferon-γ in response to the activation by CCA cells expressing MUC1, including KKU-055 (27.18 ± 4.38% and 27.33 ± 5.55%, respectively, P < 0.05) and KKU-213A (47.37 ± 12.67% and 54.55 ± 8.66%, respectively, P < 0.01). Remarkably, the cytotoxic function of αM.CAR/SR T cells against KKU-213A cells expressing PD-L1 was significantly enhanced compared with the αM.CAR T cells (70.69 ± 14.38% versus 47.15 ± 8.413%, respectively; P = 0.0301), correlated with increased granzyme B production (60.6 ± 9.89% versus 43.2 ± 8.95%, respectively; P = 0.0402). Moreover, the significantly enhanced disruption of KKU-213A spheroids by αM.CAR/SR T cells (P = 0.0027), compared with αM.CAR T cells, was also observed. CONCLUSION: Taken together, the cytotoxic function of αM.CAR/SR T cells was enhanced over the αM.CAR T cells, which are potential to be further tested for CCA treatment.

Combination gemcitabine and PD-L1xCD3 bispecific T cell engager (BiTE) enhances T lymphocyte cytotoxicity against cholangiocarcinoma cells.

Cholangiocarcinoma (CCA) is a lethal cancer with rapid progression and poor survival. Novel and more effective therapies than those currently available are, therefore, urgently needed. Our research group previously reported the combination of gemcitabine and cytotoxic T lymphocytes to be more effective than single-agent treatment for the elimination of CCA cells. However, gemcitabine treatment of CCA cells upregulates the expression of an immune checkpoint protein (programmed death-ligand 1 [PD-L1]) that consequently inhibits the cytotoxicity of T lymphocytes. To overcome this challenge and take advantage of PD-L1 upregulation upon gemcitabine treatment, we generated recombinant PD-L1xCD3 bispecific T cell engagers (BiTEs) to simultaneously block PD-1/PD-L1 signaling and recruit T lymphocytes to eliminate CCA cells. Two recombinant PD-L1xCD3 BiTEs (mBiTE and sBiTE contain anti-PD-L1 scFv region from atezolizumab and from a published sequence, respectively) were able to specifically bind to both CD3 on T lymphocytes, and to PD-L1 overexpressed after gemcitabine treatment on CCA (KKU213A, KKU055, and KKU100) cells. mBiTE and sBiTE significantly enhanced T lymphocyte cytotoxicity against CCA cells, especially after gemcitabine treatment, and their magnitudes of cytotoxicity were positively associated with the levels of PD-L1 expression. Our findings suggest combination gemcitabine and PD-L1xCD3 BiTE as a potential alternative therapy for CCA.

Antitumor activity of T cells secreting αCD133-αCD3 bispecific T-cell engager against cholangiocarcinoma.

Cholangiocarcinoma (CCA) is a lethal cancer of bile duct epithelial cells with a high mortality rate and limited therapeutic options. An effective treatment is, therefore, urgently needed to improve treatment outcomes for these patients. To develop a new therapeutic option, we engineered T cells secreting αCD133-αCD3 bispecific T-cell engager and evaluated their antitumor effects against CD133-expressing CCA cells. The cDNA encoding αCD133-αCD3 bispecific T-cell engager (αCD133-αCD3-ENG) was cloned into pCDH lentiviral construct and its expression was tested in Lenti-X 293T cells. T cells from healthy donors were then transduced with engineered lentiviruses to create T cells secreting αCD133-αCD3 engager to evaluate their antitumor activities. The average transduction efficiency into T cells was approximately 60.03±21.65%. In the co-culture system containing T cells secreting αCD133-αCD3 engager (as effector cells) and mWasabi-luciferase-expressing CCA cells (KKU-100 and KKU-213A; as target cells), the effector T cells exhibited significantly higher cytolytic activities against the target CCA cells (49.0±9.76% and 64.10±13.18%, respectively) than those observed against the untransduced T cells (10.97±10.65%; p = 0.0103 and 9.80±11.05%; p = 0.0054) at an effector-to-target ratio of 5:1. In addition, the secreted αCD133-αCD3 engager significantly redirected both transduced T cells and bystander T cells to kill the target CCA cells (up to 73.20±1.68%; p<0.05). Moreover, the transduced and bystander T cells could kill the target CCA spheroids at a rate approximately 5-fold higher than that of the no treatment control condition (p = 0.0011). Our findings demonstrate proof-of-principle that T cells secreting αCD133-αCD3 engager can be an alternative approach to treating CD133-positive CCA, and they pave the way for future in vivo study and clinical trials.

Anti-mucin 1 chimeric antigen receptor T cells for adoptive T cell therapy of cholangiocarcinoma.

Current treatments for cholangiocarcinoma (CCA) are largely unsuccessful due to late diagnosis at advanced stage, leading to high mortality rate. Consequently, improved therapeutic approaches are urgently needed. Chimeric antigen receptor (CAR) T cell therapy is a newly potential therapy that can recognize specific surface antigen without major histocompatibility complex (MHC) restriction. Mucin 1 (MUC1) is an attractive candidate antigen as it is highly expressed and associated with poor prognosis and survival in CCA. We, therefore, set forth to create the fourth-generation CAR (CAR4) construct containing anti-MUC1-single-chain variable fragment (scFv) and three co-stimulatory domains (CD28, CD137, and CD27) linked to CD3ζ and evaluate anti-MUC1-CAR4 T cells in CCA models. Compared to untransduced T cells, anti-MUC1-CAR4 T cells produced increased levels of TNF-α, IFN-γ and granzyme B when exposed to MUC1-expressing KKU-100 and KKU-213A CCA cells (all p < 0.05). Anti-MUC1-CAR4 T cells demonstrated specific killing activity against KKU-100 (45.88 ± 7.45%, p < 0.05) and KKU-213A cells (66.03 ± 3.14%, p < 0.001) at an effector to target ratio of 5:1, but demonstrated negligible cytolytic activity against immortal cholangiocytes. Furthermore, the anti-MUC1-CAR4 T cells could effectively disrupt KKU-213A spheroids. These activities of anti-MUC1-CAR4 T cells supports the development of this approach as an adoptive T cell therapeutic strategy for CCA.

Anti-tumour effect of the fourth-generation chimeric antigen receptor T cells targeting CD133 against cholangiocarcinoma cells.

Current treatment of cholangiocarcinoma (CCA) - a lethal bile duct cancer - is ineffective because the disease is usually diagnosed at late and advanced stage. Thus, a novel therapeutic modality is urgently required. Fourth-generation chimeric antigen receptor (CAR4) T cells was created to target CD133, a well-known cancer stem cell marker, that is highly expressed and associates with cancer progression. The anti-CD133-CAR4 T cells showed high efficacy against CD133-expressing CCA cells. Tumour cell lysis occurred in a dose- and CD133 antigen-dependent manner, and significantly higher, up to 57.59% ± 9.62 at effector to target ratio of 5:1 in a CCA cell line - KKU-213A cells, compared to mock control (p = 0.008). Similarly, significant IFN-γ (p = 0.011) and TNF-α (p = 0.002) upregulation was observed upon tumour treatment. The effectiveness of our anti-CD133-CAR4 T cells will be beneficial not only for CD133-expressing CCA, but also for other CD133-expressing tumours. This study may guide future in vivo study and clinical trials.