Combination of novel intravesical xenogeneic urothelial cell immunotherapy and chemotherapy enhances anti-tumor efficacy in preclinical murine bladder tumor models.

BACKGROUND: Immune checkpoint inhibitors induce robust and durable responses in advanced bladder cancer (BC), but only for a subset of patients. Xenovaccination has been proposed as an effective immunotherapeutic approach to induce anti-tumor immunity. Thus, we proposed a novel intravesical xenogeneic urothelial cell immunotherapy strategy to treat advanced BC based on the hypothesis that implanted xenogeneic urothelial cells not only provoke xeno-rejection immune responses but also elicit bystander anti-tumor immunity. METHODS: Mouse advanced bladder cancer models were treated with vehicle control, intravesical xenogeneic urothelial cells, cisplatin + gemcitabine, or the combination and assessed for tumor responses to treatments. Tumors and spleens samples were collected for immunohistological staining, cellular and molecular analysis assessed by antibody staining, ELISA, cytotoxicity, and flow cytometry, respectively. RESULTS: The combination treatment of xenogeneic urothelial cell immunotherapy with chemotherapy was more efficacious than either single therapy to extend survival time in MBT-2 graft bladder tumor model and to suppress tumor progression in murine carcinogen BBN-induced bladder tumor model. The single-cell immunotherapy and combined therapy increased more tumor-infiltrating immune cells in MBT-2 graft tumors compared to vehicle control and chemotherapy treatment groups. The activated T-cell proliferation, cytokine production, and cytotoxicity capacities were also higher in mice with xenogeneic urothelial cell immunotherapy and combination treatments. CONCLUSIONS: Our results suggest the potential for a novel xenogeneic urothelial cell-based immunotherapy alone and synergy with chemotherapy in the combination therapy. Therefore, our study supports developing xenogeneic urothelial cells as an immunotherapeutic agent in combination with chemotherapy for BC treatment.

Intratumoral xenogeneic tissue-specific cell immunotherapy inhibits tumor growth by increasing antitumor immunity in murine triple negative breast and pancreatic tumor models.

Low immunogenicity in tumors and the immunosuppressive tumor microenvironment (TME) represent major obstacles to the full success of immunotherapy in cancer patients. A novel intratumoral xenogeneic tissue-specific cell immunotherapeutic approach could overcome the obstacles. Murine 4T1 triple negative breast cancer (TNBC) cells and Pan18 pancreatic ductal adenocarcinoma (PDAC) cells were used for establishing syngeneic graft tumor models to evaluate antitumor effect of intratumoral injection of xenogeneic tissue-specific cells. Responses to treatment were assessed by measuring tumor growth and tumor weight of the tumor-bearing mice. To investigate the mechanisms of action, tumor histology and immunohistochemistry and cytokine gene expression were measured. Splenic lymphocytes proliferation, cytokine production and cytotoxicity activities were also assessed. The findings showed that intratumoral injection of xenogeneic tissue-specific cells in monotherapy and combination with chemotherapy inhibit tumor growth. The therapeutic efficacy of intratumoral xenogeneic cells was significantly enhanced by the addition of cytotoxic chemotherapeutic agents. Mice that received combined treatment showed maximal attenuation in tumor growth rate. The antitumor immunity was explained by altered immune cell infiltration in tumors and immune cell functions. Our findings demonstrate that xenogeneic tissue-specific cells given intratumorally, provide a potent antitumor effect in murine breast and pancreatic tumor models by enhancing recruitment and activation of immune cells in tumors for local and systemic antitumor effects. Moreover, intratumoral xenogeneic cell treatment turns immunologically "cold" tumors to "hot" ones, generates systemic antitumor immunity, and synergizes with chemotherapy. Thus, the intratumoral xenogeneic tissue-specific cell immunotherapy may represent a useful therapeutic option to difficult-to-treat cancers.

Intravesical Administration of Xenogeneic Porcine Urothelial Cells Attenuates Cyclophosphamide-Induced Cystitis in Mice.

The urothelium of the bladder, renal pelvis, ureter and urethra is maintained through the regulated proliferation and differentiation of urothelial stem and progenitor cells. These cells provide a rich source of a novel urothelial cell therapy approach that could be used to protect, regenerate, repair and restore a damaged urothelium. Urothelial injury caused by physical, chemical and microbial stress is the pathological basis of cystitis (bladder inflammation). The loss of urothelial integrity triggers a series of inflammatory events, resulting in pain and hematuria such as hemorrhage cystitis and interstitial cystitis. Here we investigate a novel cell therapy strategy to treat cystitis by protecting the urothelium from detrimental stresses through intravesically instilling porcine urothelial cells (PUCs) into the bladder. Using a chemical-induced urothelial injury mouse model of cyclophosphamide (CPP)-induced hemorrhagic cystitis, we determined how the intravesical instillation of PUCs could protect the urothelium from toxic attack from CPP metabolites. We show that intravesical PUC instillation protected the bladder from toxic chemical attack in mice receiving CPP with reduced inflammation and edema. Compared with the vehicle control mice, the proliferative response to chemical injury and apoptotic cells within the bladder tissues were reduced by intravesical PUC treatment. Furthermore, the urothelium integrity was maintained in the intravesical PUC-treated group. After xenogeneic PUCs were introduced and adhered to the mouse urothelium, immunological rejection responses were observed with increased neutrophil infiltration in the lamina propria and higher immune-related gene expression. Our findings provide an innovative and promising intravesical PUC cell therapy for cystitis with urothelial injury by protecting the urothelium from noxious agents.