Inflammatory cytokines predominate in cases of tumor regression after hematopoietic stem cell transplantation for solid cancer

PPARγ activation reduces ischemia/reperfusion-induced metastasis in a murine model of hepatocellular carcinoma

Ischemia/reperfusion (I/R) injury during liver resection or transplantation for the treatment of hepatocellular carcinoma (HCC) may increase the risk of metastasis. Peroxisome proliferator-activated receptor-γ (PPARγ) activation has been observed to exert a protective effect against hepatic I/R injury. However, whether PPARγ activation exerts a protective effect against I/R-associated liver metastasis remains unknown. Therefore, the present study aimed to investigate the effects of the PPAR agonist rosiglitazone and the specific PPARγ antagonist GW9662 on tumor metastasis following hepatic I/R. An experimental mouse model of hepatic I/R-induced HCC metastasis was designed in order to determine the effects of I/R on tumor metastasis in the liver. Four groups were established: Sham, control (I/R), rosiglitazone (Ro) and rosiglitazone with GW9662 (Ro + GW) groups. In the latter two groups, the treatments were administered intravenously 1 h prior to the induction of ischemia. Tumor load was measured 12 days after the procedure. Furthermore, tissue analyses were conducted to determine the expression levels of alanine aminotransferase, myeloperoxidase (MPO), matrix metalloproteinase (MMP)-9, vascular cell adhesion molecule (VCAM)-1, nuclear factor (NF)-κB and PPARγ. Rosiglitazone pretreatment appeared to significantly mitigate hepatic I/R injury, as indicated by serological and histological analysis. The levels of VCAM-1, MPO and MMP-9 expression in the Ro group were significantly reduced at 8 h following ischemia compared with those in the control and Ro + GW groups. In addition, rosiglitazone inhibited the I/R-induced activation of NF-κB, and GW9662 attenuated the inhibitory effect. To the best of our knowledge, the present study is the first to report on the expression and the functional roles of PPARγ in I/R-associated metastasis. Short-term treatment of mice with rosiglitazone, a potent PPARγ agonist, confers protective effects against hepatic I/R-associated metastasis. Thus, PPARγ may be a potential therapeutic target for the protection of the liver against I/R-associated metastasis.

Cytokine expression in tumors treated with donor lymphocyte infusions after allogeneic hematopoietic stem cell transplantation

AIMS

Risk factors for disease relapse are remaining tumor or leukemic cells or mixed chimerism (MC) following allogeneic hematopoietic stem cell transplantation. Donor lymphocyte infusion (DLI) after stem cell transplantation can contribute to complete donor chimerism and graft-versus-tumor/leukemia effect. We evaluate cytokine secretion at the single-cell level using ELISpot in relation to DLI effect on disease response.

PATIENTS & METHODS

Blood samples were collected from four patients with solid tumors and four with hematological malignancies before DLI, and 1 and 3 weeks after DLI. Tumor response was evaluated according to the international Response Evaluation Criteria In Solid Tumors (RECIST) method. Indications for DLI were stable disease or MC and/or progressive disease in solid tumors, and molecular or early relapse, or MC in hematological malignancies. ELISpot was performed for TNF-α, IFN-γ, IL-12, IL-4, IL-10 and IL-13 cytokines.

RESULTS

Depending on the disease response, patients were divided into two groups: responders and nonresponders. Responders were patients who achieved partial response (one renal cell cancer) or stable disease (one prostate cancer) or clinical remission (two acute myeloid leukemia). Patients who relapsed, progressed or rejected the graft were the nonresponders. DLI rescued the renal cell cancer patient, who has partial response, and two acute myeloid leukemia patients, who are in clinical remission. Patients who responded tended to have a higher expression of TNF-α, IFN-γ, IL-12 and IL-10 than those who did not respond.

CONCLUSIONS

DLI can act when the patients' mononuclear cells have normal or increased capacity to produce TNF-α, IFN-γ, IL-12 and IL-10. Assessment of these cytokines may be useful to predict those patients who will respond to DLI therapy.

Nonmyeloablative allogeneic hematopoietic stem cell transplantation as immunotherapy for pancreatic cancer

OBJECTIVE

Advanced unresectable pancreatic cancer has an extremely poor prognosis despite intensive chemotherapy. As a new therapeutic modality, we investigated nonmyeloablative allogeneic hematopoietic stem cell transplantation from a related donor.

METHODS

Five patients with chemotherapy-resistant pancreatic cancer received allogeneic peripheral blood stem cell transplantation after a conditioning regimen consisting of low-dose total body irradiation and fludarabine. The prophylaxis for graft-versus-host disease consisted of mycophenolate mofetil and cyclosporine.

RESULTS

The median age of the 5 patients was 54 years, and the median duration from diagnosis to nonmyeloablative allogeneic hematopoietic stem cell transplantation was 10 months. Three of the 5 patients achieved complete donor chimerism of peripheral T cells, at a median time of day 42. Acute graft-versus-host disease developed in 3 patients: grade 2 in 2 patients and grade 1 in 1. Tumor reduction was observed in 2 patients: 1 patient showed disappearance of the pancreatic tumor, and the other patient showed approximately 20% reduction of the tumor. Marked elevation of tumor necrosis factor alpha was observed as the tumor regressed.

CONCLUSIONS

Although advanced pancreatic cancer progresses rapidly, some graft-versus-tumor effects and pivotal role of tumor necrosis factor alpha were suggested. To obtain the durable response, patient selection and new strategies become important.

Completely mismatched allogeneic CD3/CD28 cross-linked Th1 memory cells elicit anti-leukemia effects in unconditioned hosts without GVHD toxicity

Fully allogeneic CD3/CD28 cross-linked Th1 cells were found to elicit host-mediated anti-leukemia effects without GVHD toxicity. Mice inoculated with a lethal dose of BCL1 leukemia demonstrated significantly enhanced survival after allogeneic Th1 treatment. Cure rates of 12.5% with a single allogeneic cell infusion and 31.25% with multiple infusions were demonstrated. Cured mice were able to reject rechallenge with a lethal dose of tumor without further treatment. These results suggest that use of intentionally mis-matched, Th1 memory cells infused with cross-linked CD3/CD28 could represent a novel clinical approach to eliciting potent anti-tumor effects in patients without conditioning and without GVHD toxicity.

The anti-tumor effect of allogeneic bone marrow/stem cell transplant without graft vs. host disease toxicity and without a matched donor requirement?

The anti-tumor immune response that occurs in allogeneic bone marrow/stem cell transplant (BMT) settings is capable of eradicating tumors that are resistant to chemotherapy/radiation treatment. This anti-tumor immune response, known as the graft vs. tumor (GVT) effect, is the most effective immunotherapy treatment ever discovered. Unfortunately, the clinical application of GVT is severely limited due to the intimate association of GVT with the extremely toxic and often lethal side-effect known as graft vs. host disease (GVHD). It is a major research focus in the field of BMT to develop methods to separate the beneficial GVT effect from the detrimental GVHD toxicity. However, due to the intimate association of these effects, attempts to limit GVHD also have a tendency to limit the GVT effect. We propose a new concept for harnessing the power of the GVT effect without the toxicity of GVHD. Rather than trying to separate GVT from GVHD, we propose that these naturally coupled effects can 'mirrored' onto the host immune system and maintain their intimate association. The 'mirror' of GVHD is a host rejection of a graft (HVG). As rejection of an allograft would not be toxic, an HVG effect coupled to a host vs. tumor (HVT) effect, the 'mirror' of the GVT effect, would provide the anti-tumor effect of BMT without GVHD toxicity. In the 'mirror' setting, the HVT effect must occur against syngeneic tumors, while in the BMT setting the GVT effect occurs in the allogeneic setting. Previous attempts to elicit syngeneic anti-tumor immunity using therapeutic tumor vaccines have had disappointing results in the clinic due to the influence of tumor immunoavoidance mechanisms. We propose that the 'danger' signals that are released as a result of GVHD in the allogeneic BMT setting serve as an adjuvant to the GVT effect disabling tumor immunoavoidance. The chemotherapy/radiation conditioning prior to transplant is a required initiating event to the coupled GVT/GVHD effects. The conditioning releases 'danger' signals that mediate this adjuvant effect. To imitate this immunological event in immunocompetent, non-conditioned patients we propose that infusion of freshly activated, polyclonal CD4+ memory Th1 cells which express CD40L on the cell surface will stimulate a HVT/HVG 'mirror' effect, providing a non-toxic means to elicit the effective immune-mediated anti-tumor effect of BMT without the GVHD toxicity and without the requirement for a matched donor.

Semi-allogeneic dendritic cells can induce antigen-specific T-cell activation, which is not enhanced by concurrent alloreactivity

BACKGROUND

Alloreactive T-cell responses are known to result in the production of large amounts of proinflammatory cytokines capable of activating and maturing dendritic cells (DC). However, it is unclear whether these allogeneic responses could also act as an adjuvant for concurrent antigen-specific responses.

OBJECTIVE

To examine effects of simultaneous alloreactive and antigen-specific T-cell responses induced by semi-allogeneic DC.

METHODS

Semi-allogeneic DC were generated from the F(1) progeny of inbred strains of mice (C57BL/6 and C3H, or C57BL/6 and DBA). We directly primed antigen-specific CD8(+) and CD4(+) T-cells from OT-I and OT-II mice, respectively, in the absence of allogeneic responses, in vitro, and in the presence or absence of alloreactivity in vivo.

RESULTS

In vitro, semi-allogeneic DC cross-presented ovalbumin (OVA) to naïve CD8(+) OT-I transgenic T-cells, primed naïve CD4(+) OT-II transgenic T-cells and could stimulate strong alloreactive T-cell proliferation in a primary mixed lymphocyte reaction (MLR). In vivo, semi-allogeneic DC migrated efficiently to regional lymph nodes but did not survive there as long as autologous DC. In addition, they were not able to induce cytotoxic T-lymphocyte (CTL) activity to a target peptide, and only weakly stimulated adoptively transferred OT-II cells. The CD4(+) response was unchanged in allo-tolerized mice, indicating that alloreactive T-cell responses could not provide help for concurrently activated antigen-specific responses. In an EL4 tumour-treatment model, vaccination with semi-allogeneic DC/EL4 fusion hybrids, but not allogeneic DC/EL4 hybrids, significantly increased mouse survival.

CONCLUSION

Expression of self-Major histocompatibility complex (MHC) by semi-allogeneic DC can cause the induction of antigen-specific immunity, however, concurrently activated allogeneic bystander responses do not provide helper or adjuvant effects.

Reduced intensity conditioning for allogeneic hematopoietic cell transplantation: current perspectives

Allogeneic HCT after myeloablative conditioning is an effective therapy for patients with hematologic malignancies. In an attempt to extend this therapy to older patients or those with comorbidities, reduced intensity or truly nonmyeloablative regimens have been developed over the past decade. The principle underlying reduced intensity regimens is to provide some tumor kill with lessened regimen-related morbidity and mortality and then rely on graft-versus-tumor (GVT) effects to eradicate remaining malignant cells, whereas nonmyeloablative regimens rely primarily on GVT effects. In this article, 3 representative approaches are described, demonstrating the clinical application for hematopoietic and nonhematopoietic malignancies. Current challenges include controlling GVHD while allowing GVT to occur. In the future, clinical trials using reduced intensity and nonmyeloablative conditioning will be compared with myeloablative conditioning in selected malignancies to extend the application to standard-risk patients.