InVivoMAb anti-mouse CD19

PURPOSE: Immunomodulatory mAbs can treat cancer, but cures are rare except for small tumors. Our objective was to explore whether the therapeutic window increases by combining mAbs with different modes of action and injecting them into tumors. EXPERIMENTAL DESIGN: Combinations of mAbs to CD137/PD-1/CTLA-4 or CD137/PD-1/CTLA-4/CD19 were administrated intratumorally to mice with syngeneic tumors (B16 and SW1 melanoma, TC1 lung carcinoma), including tumors with a mean surface of approximately 80 mm(2). Survival and tumor growth were assessed. Immunologic responses were evaluated using flow cytometry and qRT-PCR. RESULTS: More than 50% of tumor-bearing mice had complete regression and long-term survival after tumor injection with mAbs recognizing CD137/PD-1/CTLA-4/CD19 with similar responses in three models. Intratumoral injection was more efficacious than intraperitoneal injection in causing rejection also of untreated tumors in the same mice. The three-mAb combination could also induce regression, but was less efficacious. There were few side effects, and therapy-resistant tumors were not observed. Transplanted tumor cells rapidly caused a Th2 response with increased CD19 cells. Successful therapy shifted this response to the Th1 phenotype with decreased CD19 cells and increased numbers of long-term memory CD8 effector cells and T cells making IFNgamma and TNFalpha. CONCLUSIONS: Intratumoral injection of mAbs recognizing CD137/PD-1/CTLA-4/CD19 can eradicate established tumors and reverse a Th2 response with tumor-associated CD19 cells to Th1 immunity, whereas a combination lacking anti-CD19 is less effective. There are several human cancers for which a similar approach may provide clinical benefit.

40% of mice with SW1 tumors remained healthy >150 days after last treatment and are probably cured. Therapeutic efficacy was associated with a systemic immune response with memory and antigen specificity, required CD4 cells and involved CD8 cells and NK cells to a less extent. The 3 mAb combination significantly decreased CD19 cells at tumor sites, increased IFN-gamma and TNF-alpha producing CD4 and CD8 T cells and mature CD86 dendritic cells (DC), and it increased the ratios of effector CD4 and CD8 T cells to CD4Foxp3 regulatory T (Treg) cells and to CD11bGr-1 myeloid suppressor cells (MDSC). This is consistent with shifting the tumor microenvironment from an immunosuppressive Th2 to an immunostimulatory Th1 type and is further supported by PCR data. Adding an anti-CD19 mAb to the 3 mAb combination in the SW1 model further increased therapeutic efficacy. Data from ongoing experiments show that intratumoral injection of a combination of mAbs to CD137PD-1CTLA4CD19 can induce complete regression and dramatically prolong survival also in the TC1 carcinoma and B16 melanoma models, suggesting that the approach has general validity.”}” data-sheets-userformat=”{“2″:14851,”3”:{“1″:0},”4”:{“1″:2,”2″:16777215},”12″:0,”14”:{“1″:2,”2″:1521491},”15″:”Roboto, sans-serif”,”16″:12}”>Mice with intraperitoneal ID8 ovarian carcinoma or subcutaneous SW1 melanoma were injected with monoclonal antibodies (mAbs) to CD137PD-1CTLA4 7-15 days after tumor initiation. Survival of mice with ID8 tumors tripled and >40% of mice with SW1 tumors remained healthy >150 days after last treatment and are probably cured. Therapeutic efficacy was associated with a systemic immune response with memory and antigen specificity, required CD4 cells and involved CD8 cells and NK cells to a less extent. The 3 mAb combination significantly decreased CD19 cells at tumor sites, increased IFN-gamma and TNF-alpha producing CD4 and CD8 T cells and mature CD86 dendritic cells (DC), and it increased the ratios of effector CD4 and CD8 T cells to CD4Foxp3 regulatory T (Treg) cells and to CD11bGr-1 myeloid suppressor cells (MDSC). This is consistent with shifting the tumor microenvironment from an immunosuppressive Th2 to an immunostimulatory Th1 type and is further supported by PCR data. Adding an anti-CD19 mAb to the 3 mAb combination in the SW1 model further increased therapeutic efficacy. Data from ongoing experiments show that intratumoral injection of a combination of mAbs to CD137PD-1CTLA4CD19 can induce complete regression and dramatically prolong survival also in the TC1 carcinoma and B16 melanoma models, suggesting that the approach has general validity.

BACKGROUND: T-cell immunoglobulin and mucin domain 3 (TIM-3) is known as a negative immune regulator and emerging data have implicated TIM-3 a pivotal role in suppressing antitumor immunity. The co-stimulatory receptor CD137 is transiently upregulated on T-cells following activation and increases their proliferation and survival when engaged. Although antagonistic anti-TIM-3 or agonistic anti-CD137 antibodies can promote the rejection of several murine tumors, some poorly immunogenic tumors were refractory to this treatment. In this study, we sought to evaluate whether combined TIM-3 blockade and CD137 activation would significantly improve the immunotherapy in the murine ID8 ovarian cancer model. METHODS: Mice with established ID8 tumor were intraperitoneally injected with single or combined anti-TIM-3/CD137 monoclonal antibody (mAb); mice survival was recorded, the composition and gene expression of tumor-infiltrating immune cells in these mice was analyzed by flow cytometry and quantitative RT-PCR respectively, and the function of CD8(+) cells was evaluated by ELISA and cytotoxicity assay. RESULTS: Either anti-TIM-3 or CD137 mAb alone, although effective in 3 days established tumor, was unable to prevent tumor progression in mice bearing 10 days established tumor, however, combined anti-TIM-3/CD137 mAb significantly inhibited the growth of these tumors with 60% of mice tumor free 90 days after tumor inoculation. Therapeutic efficacy was associated with a systemic immune response with memory and antigen specificity, required CD4(+) cells and CD8(+) cells. The 2 mAb combination increased CD4(+) and CD8(+) cells and decreased immunosuppressive CD4(+)FoxP3(+) regulatory T (Treg) cells and CD11b(+)Gr-1(+) myeloid suppressor cells (MDSC) at tumor sites, giving rise to significantly elevated ratios of CD4(+) and CD8(+) cells to Treg and MDSC; This is consistent with biasing local immune response towards an immunostimulatory Th1 type and is further supported by quantitative RT-PCR data showing the increased Th1-associated genes by anti-TIM-3/CD137 treatment. The increased CD8(+) T cells produced high level of IFN-gamma upon tumor antigen stimulation and displayed antigen-specific cytotoxic activity. CONCLUSIONS: To our knowledge, this is the first report investigating the effects of anti-TIM-3/CD137 combined mAb in a murine ovarian cancer model, and our results may aid the design of future trials for ovarian cancer immunotherapy.

Aging is associated with a decline in B-lymphopoiesis in the bone marrow and accumulation of long-lived B cells in the periphery. These changes decrease the body’s ability to mount protective antibody responses. We show here that age-related changes in the B lineage are mediated by the accumulating long-lived B cells. Thus, depletion of B cells in old mice was followed by expansion of multipotent primitive progenitors and common lymphoid progenitors, a revival of B-lymphopoiesis in the bone marrow, and generation of a rejuvenated peripheral compartment that enhanced the animal’s immune responsiveness to antigenic stimulation. Collectively, our results suggest that immunosenescence in the B-lineage is not irreversible and that depletion of the long-lived B cells in old mice rejuvenates the B-lineage and enhances immune competence.