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Fetal porcine islet-like cell clusters (ICC) were transplanted under the renal capsule of normoglycemic normal or athymic (nu/nu) C57BL/6 mice. Control animals were implanted with allogeneic minced kidney tissue from C57BL/Ks mice. The animals were killed 6 or 14 days after transplantation and the grafts were processed for flow cytometric analyses or immunohistochemistry. Xenograft destruction was evident in normal mice on day 6 after transplantation. The majority of infiltrating cells were macrophage-like cells expressing the F4/80 antigen. Lymphocytes expressing the CD3 antigen were in minority and mainly located in the peripheral parts of the ICC xenograft. The frequency and distribution of CD4+ cells were found to resemble those of the CD3+ cells. A large number of infiltrating cells, including several macrophage-like cells, expressed the Thy 1.2 antigen. Flow cytometry of infiltrating cells in the ICC xenograft revealed that approximately half of the cells expressing the F4/80 antigen also expressed Thy 1.2 and/or CD4. No cells were found expressing both the F4/80 and CD8 antigens. Both the F4/80 single-positive and the F4/80, CD4 double-positive cells were found to be larger and more granular than the CD4 single-positive cells. No co-expression of CD4 or Thy 1.2 with the F4/80 antigen was detected on cells infiltrating allogeneic tissue grafts. Moreover, a relative large number of cells (approximately 15%) in the xenograft expressed the NK 1.1 antigen as determined by flow cytometry. The role of natural killer (NK) cells in islet xenograft rejection was further evaluated in mice depleted of NK cells, using intraperitoneal injections of the monoclonal antibody NK 1.1. The simultaneous inoculation and subsequent growth of the NK cell-sensitive beta 2-microglobulin-deficient mutant, C4.4-25-, lymphoma cell line EL-4 served as an in vivo control of NK cell depletion. However, all NK cell-depleted mice rejected the ICC xenograft. In contrast, athymic mice permanently accepted the porcine ICC xenograft but, readily rejected the NK cell-sensitive lymphoma cell line. Taken together, ICC xenograft rejection in mice seems to be T cell dependent, as evidenced in the nude mice model, while the main effector cell appears to be a macrophage with a unique phenotype.

BackgroundAccumulating pre-clinical data indicate that the efficient induction of antigen-specific cytotoxic CD8+ T cells characterizing viral infections is caused by cross-priming where initially infected DCs produce an unique set of inflammatory factors that recruit and activate non-infected bystander DCs. Our DC-based immunotherapy concept is guided by such bystander view and accordingly, we have developed a cellular adjuvant consisting of pre-activated allogeneic DCs producing high levels of DC-recruiting and DC-activating factors. This concept doesn’t require MHC-compatibility between injected cells and the patient and therefore introduces the possibility of using pre-produced and freeze-stored DCs from healthy blood donors as an off- the-shelf immune enhancer. The use of MHC-incompatible allogeneic DCs will further induce a local rejection process at the injection site that is expected to further enhance recruitment and maturation of endogenous bystander DCs.MethodsTwelve intermediate and poor risk patients with newly diagnosed metastatic renal cell carcinoma (mRCC) where included in a phase I/II study. Pro-inflammatory allogeneic DCs were produced from a leukapheresis product collected from one healthy blood donor and subsequently deep-frozen. A dose of 5–20 × 106 DCs (INTUVAX) was injected into the renal tumor twice with 2 weeks interval before planned nephrectomy and subsequent standard of care.ResultsNo INTUVAX-related severe adverse events were observed. A massive infiltration of CD8+ T cells was found in 5 out of 12 removed kidney tumors. No objective tumor response was observed and 6 out of 11 evaluable patients have subsequently received additional treatment with standard tyrosine kinase inhibitors (TKI). Three of these 6 patients experienced an objective tumor response including one sunitinib-treated patient who responded with a complete and durable regression of 4 brain metastases. Median overall survival (mOS) is still not reached (currently 42.5 months) but has already passed historical mOS in patients with unfavourable risk mRCC on standard TKI therapy.ConclusionsOur findings indicate that intratumoral administration of proinflammatory allogeneic DCs induces an anti-tumor immune response that may prolong survival in unfavourable risk mRCC-patients given subsequent standard of care. A randomized, multi-center, phase II mRCC trial (MERECA) with INTUVAX in conjuction with sunitinib has been initiated.Trial registrationClinicaltrials.gov identifier: NCT01525017.

Adoptive T-cell therapy of cancer is a treatment strategy where T cells are isolated, activated, in some cases engineered, and expanded ex vivo before being reinfused to the patient. The most commonly used T-cell expansion methods are either anti-CD3/CD28 antibody beads or the “rapid expansion protocol” (REP), which utilizes OKT-3, interleukin (IL)-2, and irradiated allogeneic feeder cells. However, REP-expanded or bead-expanded T cells are sensitive to the harsh tumor microenvironment and often short-lived after reinfusion. Here, we demonstrate that when irradiated and preactivated allosensitized allogeneic lymphocytes (ASALs) are used as helper cells to license OKT3-armed allogeneic mature dendritic cells (DCs), together they expand target T cells of high quality. The ASAL/DC combination yields an enriched Th1-polarizing cytokine environment (interferon (IFN)-γ, IL-12, IL-2) and optimal costimulatory signals for T-cell stimulation. When genetically engineered antitumor T cells were expanded by this coculture system, they showed better survival and cytotoxic efficacy under oxidative stress and immunosuppressive environment, as well as superior proliferative response during tumor cell killing compared to the REP protocol. Our result suggests a robust ex vivo method to expand T cells with improved quality for adoptive cancer immunotherapy.