Allogeneic MHC gene transfer enhances an effective antitumor immunity in the early period of autologous hematopoietic stem cell transplantation

Lymphopenic condition enhanced the antitumor immunity of PD-1-knockout T cells mediated by CRISPR/Cas9 system in malignant melanoma

BACKGROUND

Adoptive transfer of PD-1 knockout T cells mediated by CRISPR/Cas9 technology has been used in various cancers and got satisfactory treatment effectiveness. However, the effectiveness was limited due to the low proliferation ability, antigen recognition ability and short lifetime of T cells in vivo.

METHOD

In this study, PD-1 knockout T cells mediated by CRISPR/Cas9 system were transferred into lymphopenic mice after sub-lethal dose of total body irradiation. The antitumor effects of PD-1 knockout T cells were comprehensively analyzed by flow cytometry. Moreover, PD-L1 knockout B16 cells were inoculated subcutaneously in lymphopenic mice receiving infusion of naïve T cells to value the role of PD-1/PD-L1 axis on lymphopenia-induced antitumor immunity RESULT: In this study, we found that the PD-1-knockout T cells underwent several rounds of homeostatic proliferation in vivo when they were transferred into lymphopenic mice. The number of IFN-γ-releasing CTL was significantly increased and the tumor growth was remarkably inhibited in lymphopenic mice receiving infusion of PD-1 knockout T cells. The expression of PD-L1 on tumor cells rose smartly in lymphopenic mice undergoing homeostatic proliferation. PD-L1 gene knockout on B16 melanoma cells could effectively enhance the antitumor immunity mediated by the homeostatic proliferation of T cells and significantly inhibited the growth of tumor CONCLUSION: These findings suggested that lymphopenic condition after total body irradiation might be able to create an environment to promote the PD-1 knockout T cells to recognize tumor antigen and undergo homeostatic proliferation, thus induced a more powerful antitumor immunity than adoptively transferring into immunocompetent hosts.

[Interleukin-12 over-expression in malignant melanoma B16 cells reduces programmed death-1 expression on T cells in mice with immune reconstitution]

OBJECTIVE

To investigate whether interleukin-12 (IL-12) over-expression in malignant melanoma B16 cells affects the expression level of programmed death-1 (PD-1) on T cells in mice during immune microenvironment reconstruction.

METHODS

B16 cells were transfected with an IL-12 expression lentiviral vector, and IL-12 over-expression in the cells was verified qPCR and ELISA. Plate cloning assay was used to compare the cell proliferation activity between B16 cells and B16/IL-12 cells. The expression of IL-12 protein in B16/IL-12 cells-derived tumor tissue were detected by ELISA. C57BL/6 mice were inoculated with B16 cells or B16/IL-12 cells, and 14 days later the proportion of T cells with high expression of PD-1 in the tumor-draining lymph nodes was detected by flow cytometry. Mouse models of immune reconstitution established by 650 cGy X-ray radiation were inoculated with B16 (B16+RT group) or B16/IL-12 (B16/IL-12+RT group) cells, with the mice without X-ray radiation prior to B16 cell inoculation as controls. Tumor growth in the mice was recorded at different time points, and on day 14, flow cytometry was performed to detect the proportion of T cells with high PD-1 expression in the tumor-draining lymph nodes and in the tumor tissue.

RESULTS

B16 cells infected with the IL-12-overexpressing lentiviral vector showed significantly increased mRNA and protein levels of IL-12 (P < 0.001) without obvious changes in cell viability (P>0.05). B16/IL-12 cells expressed higher levels of IL-12 than B16 cells in vivo (P < 0.01). In the tumor-bearing mouse models, the proportion of CD4 ⁺ PD-1⁺ T cells was significantly lower in B16/IL-12 group than in B16 group (P < 0.01). In the mice with X-ray radiation-induced immune reconstitution, PD-1 expressions on CD4⁺ T cells (P < 0.05) and CD8+ T cells (P < 0.01) were significantly higher in B16+ RT group than in the control mice and in B16/IL-12+RT group (P < 0.01 or 0.001); the tumors grew more slowly in B16/IL-12+RT group than in B16 + RT group (P < 0.001).

CONCLUSIONS

During immune microenvironment reconstruction, overexpression IL-12 in the tumor microenvironment can reduce the percentage of PD-1 ⁺ T cells and suppress the growth of malignant melanoma in mice.

Prognostic Role of a New Index (RAPID Index) in Advanced Hepatocellular Carcinoma Patients Receiving Sorafenib: Training and Validation Cohort

Background and Aims

The aim of the present study is to evaluate a new index influenced by the balance between the immune system, α-fetoprotein (AFP), and lactate dehydrogenase (LDH) (RAPID index) as a prognostic factor in patients treated with sorafenib.

Methods

This study was conducted on a training cohort of 159 hepatocellular carcinoma (HCC) patients and a validation cohort of 68 HCC patients treated with sorafenib. The RAPID index was calculated as neutrophil/lymphocyte count × LDH × AFP.

Results

In the training cohort, the median overall survival (OS) was 23.2 months (95% CI 11-25) and 12.1 months (95% CI 9-15) for patients with a low (≤3,226) and high (>3,226) RAPID index, respectively (ref. <3,226, HR = 0.56, 95% CI 0.35-0.88, p = 0.017). Following adjustment for clinical covariates, multivariate analysis confirmed the RAPID index ≤3,226 versus >3,226 (HR = 0.37, 95% CI 0.18-0.74, p = 0.0054) as an independent prognostic factor for OS. In the validation cohort, the median OS was 26.9 months (95% CI 17.6-26.9) and 7.0 months (95% CI 6.2-9.2) for patients with a low (≤ 3,226) and high (>3,226) RAPID index, respectively (ref. <3,226, HR = 0.19, 95% CI 0.10-0.36, p < 0.0001). Performing the same multivariate analysis of the training cohort (AFP, Eastern Cooperative Oncology Group, aspartate aminotransferase, neutrophil, platelet, systemic inflammatory index and RAPID index), the RAPID index <3,226 versus >3,226 (HR = 3.86, 95% CI 1.45-10.29, p = 0.007) was found to be an independent prognostic factor for predicting OS.

Conclusion

The low cost, easy assessment, and reproducibility of a full blood count make the RAPID index a promising tool for assessing HCC prognosis in future clinical practice.

Pre-immunization of donor lymphocytes with GITR agonistic antibody enhances antitumor immunity in autologous hematopoietic stem cell transplantation

The lymphopenic condition following autologous hematopoietic stem cell transplantation (HSCT) enhances the proliferation of T cells by engaging tumor-associated antigens, leading to the alteration of the T-cell repertoire towards antitumor immunity. However, cure by autologous HSCT alone have rarely occurred in the clinical setting. Since tumor-reactive lymphocytes preferentially proliferate during reconstitution of the immune system, we examined whether the priming of donor lymphocytes can strengthen the antitumor effect by HSCT in a CT26 murine colon cancer model. The systemic administration of an anti-glucocorticoid-induced TNF receptor (GITR) agonistic antibody (Ab) significantly increased the number of CT26-responsive T cells but not that of auto-reactive lymphocytes in donor mice. The infusion of non-primed and GITR Ab-primed donor lymphocytes suppressed the CT26 tumor growth, and only the primed lymphocytes eliminated tumors in all the treated mice. The frequency of CT26-responsive T cells was elevated in recipient mice infused with both primed and non-primed lymphocytes until 4 weeks after transplantation, while the frequency in recipients with primed lymphocytes was markedly elevated compared with that in mice harboring non-primed lymphocytes at 2 weeks. The frequencies of regulatory T cells and myeloid-derived suppressor cells were elevated in recipient mice infused with primed and non-primed lymphocytes 2 weeks after transplantation, and returned to normal levels by week 4. The combination of autologous HSCT with pre-immunization of donor lymphocytes is a promising strategy to induce strong antitumor immunity.

Preimmunization of donor lymphocytes enhances antitumor immunity of autologous hematopoietic stem cell transplantation

Lymphopenia-induced homeostatic proliferation (HP) of T cells following autologous hematopoietic stem cell transplantation (HSCT) skews the T-cell repertoire by engaging tumor-associated antigens (TAAs), leading to an induction of antitumor immunity. Here, as the tumor-reactive lymphocytes preferentially proliferate during the condition of HP, we examined whether the priming of a donor lymphocytes to TAAs could enhance HP-induced antitumor immunity in autologous HSCT recipients. First, to examine whether the tumor-bearing condition of donor influences the antitumor effect of HSCT, the lymphocytes isolated from CT26 tumor-bearing mice were infused into lethally irradiated mice. The growth of tumors was substantially suppressed in the mice that received HSCT from a tumor-bearing donor compared with a naïve donor, suggesting that a fraction of donor lymphocytes from tumor-bearing mice are primed in response to TAAs and remain responsive upon transplantation. We previously reported that type I interferon (IFN) maturates the dendritic cells and promotes the priming of T cells. We then investigated whether the further priming of donor cells by IFN-α can strengthen the antitumor effect of HSCT. The intratumoral IFN-α gene transfer significantly increased the number of IFN-γ-positive lymphocytes in response to CT26 cells but not the syngeneic lymphocytes in donor mice. The infusion of primed donor lymphocytes markedly suppressed the tumor growth in recipient mice, and cured 64% of the treated mice. Autologous HSCT with the infusion of primed donor lymphocytes is a promising strategy to induce an effective antitumor immunity for solid cancers.

Vascular endothelial growth factor-D-mediated blockade of regulatory T cells within tumors is induced by hematopoietic stem cell transplantation

Lymphopenia-induced homeostatic proliferation of T cells after autologous hematopoietic stem cell transplantation (HSCT) skews the T cell repertoire by engaging tumor-associated Ags, leading to an induction of antitumor immunity. However, how HSCT alters the immunosuppressive microenvironment in the tumors is unknown. In this study, we first analyzed the kinetics of regulatory T cells (Tregs) in the tumors after syngeneic HSCT. Unexpectedly, the frequency of CD4⁺ cells expressing Foxp3 was increased in the spleens, whereas the frequency was clearly decreased in the tumors after HSCT. The origin of reconstituted CD4⁺ and Foxp3⁺ cells in the tumors was mainly from the expansion of transferred splenic T cells. Then, to examine the mechanism of Treg suppression after HSCT, we isolated CD11c⁺ cells from tumors. A large amount of Treg-inhibitory cytokine IL-6 was secreted from the CD11c⁺ cells in the tumors, but not in the spleens in the recipient mice. Furthermore, to understand what factor affects the activity of CD11c⁺ cells in the tumors after HSCT, we analyzed the expression of various cytokines/chemokines with mouse cytokine Ab arrays, and noticed that VEGF-D concentration was increased in the tumors in the early period after HSCT. The CD11c⁺ cells produced IL-6 in response to VEGF-D stimulation, and an administration of VEGF receptor-3 neutralizing Ab significantly suppressed the production of IL-6 from CD11c⁺ cells accompanied with the increase of Tregs in the tumors of HSCT recipients. Autologous HSCT creates an environment that strongly supports the enhancement of antitumor immunity in reconstituted lymphopenic recipients through the suppression of Tregs.

Early immunisation with dendritic cells after allogeneic bone marrow transplantation elicits graft vs tumour reactivity

Background:

Perspectives of immunotherapy to cancer mediated by bone marrow transplantation (BMT) in conjunction with dendritic cell (DC)-mediated immune sensitisation have yielded modest success so far. In this study, we assessed the impact of DC on graft vs tumour (GvT) reactions triggered by allogeneic BMT.

Methods:

H2K^a mice implanted with congenic subcutaneous Neuro-2a neuroblastoma (NB, H2K^a) tumours were irradiated and grafted with allogeneic H2K^b bone marrow cells (BMC) followed by immunisation with tumour-inexperienced or tumour-pulsed DC.

Results:

Immunisation with tumour-pulsed donor DC after allogeneic BMT suppressed tumour growth through induction of T cell-mediated NB cell lysis. Early post-transplant administration of DC was more effective than delayed immunisation, with similar efficacy of DC inoculated into the tumour and intravenously. In addition, tumour inexperienced DC were equally effective as tumour-pulsed DC in suppression of tumour growth. Immunisation of DC did not impact quantitative immune reconstitution, however, it enhanced T-cell maturation as evident from interferon-γ (IFN-γ) secretion, proliferation in response to mitogenic stimulation and tumour cell lysis in vitro. Dendritic cells potentiate GvT reactivity both through activation of T cells and specific sensitisation against tumour antigens. We found that during pulsing with tumour lysate DC also elaborate a factor that selectively inhibits lymphocyte proliferation, which is however abolished by humoral and DC-mediated lymphocyte activation.

Conclusion:

These data reveal complex involvement of antigen-presenting cells in GvT reactions, suggesting that the limited success in clinical application is not a result of limited efficacy but suboptimal implementation. Although DC can amplify soluble signals from NB lysates that inhibit lymphocyte proliferation, early administration of DC is a dominant factor in suppression of tumour growth.

Novel strategies for immunotherapy in multiple myeloma: previous experience and future directions

Multiple myeloma (MM) is a life-threatening haematological malignancy for which standard therapy is inadequate. Autologous stem cell transplantation is a relatively effective treatment, but residual malignant sites may cause relapse. Allogeneic transplantation may result in durable responses due to antitumour immunity mediated by donor lymphocytes. However, morbidity and mortality related to graft-versus-host disease remain a challenge. Recent advances in understanding the interaction between the immune system of the patient and the malignant cells are influencing the design of clinically more efficient study protocols for MM. Cellular immunotherapy using specific antigen-presenting cells (APCs), to overcome aspects of immune incompetence in MM patients, has received great attention, and numerous clinical trials have evaluated the potential for dendritic cell (DC) vaccines as a novel immunotherapeutic approach. This paper will summarize the data investigating aspects of immunity concerning MM, immunotherapy for patients with MM, and strategies, on the way, to target the plasma cell more selectively. We also include the MM antigens and their specific antibodies that are of potential use for MM humoral immunotherapy, because they have demonstrated the most promising preclinical results.

Syngeneic hematopoietic stem cell transplantation enhances the antitumor immunity of intratumoral type I interferon gene transfer for sarcoma

Sarcoma at advanced stages remains a clinically challenging disease. Interferons (IFNs) can target cancer cells by multiple antitumor activities, including the induction of cancer cell death and enhancement of immune response. However, the development of an effective cancer immunotherapy is often difficult, because cancer generates an immunotolerant microenvironment against the host immune system. An autologous hematopoietic stem cell transplantation (HSCT) is expected to reconstitute a fresh immune system, and expand tumor-specific T cells through the process of homeostatic proliferation. Here we examined whether a combination of autologous HSCT and IFNs could induce an effective tumor-specific immune response against sarcoma. First, we found that a type I IFN gene transfer significantly suppressed the cell growth of various sarcoma cell lines, and that IFN-β gene transfer was more effective in inducing cell death than was IFN-α in sarcoma cells. Then, to examine the antitumor effect in vivo, human sarcoma cells were inoculated in immune-deficient mice, and a lipofection of an IFN-β-expressing plasmid was found to suppress the growth of subcutaneous tumors significantly. Finally, the IFN gene transfer was combined with syngeneic HSCT in murine osteosarcoma models. Intratumoral IFN-β gene transfer markedly suppressed the growth of vector-injected tumors and inhibited formation of spontaneous lung and liver metastases in syngeneic HSCT mice, and an infiltration of many immune cells was recognized in metastatic tumors of the treated mice. The treated mice showed no significant adverse events. A combination of intratumoral IFN gene transfer with autologous HSCT could be a promising therapeutic strategy for patients with sarcoma.

In vivo delivery of interferon-α gene enhances tumor immunity and suppresses immunotolerance in reconstituted lymphopenic hosts

T cells recognize tumor-associated antigens under the condition of lymphopenia-induced homeostatic proliferation (HP); however, HP-driven antitumor responses gradually decay in association with tumor growth. Type I interferon (IFN) has important roles in regulating the innate and adaptive immune system. In this study we examined whether a tumor-specific immune response induced by IFN-α could enhance and sustain HP-induced antitumor immunity. An intratumoral IFN-α gene transfer resulted in marked tumor suppression when administered in the early period of syngeneic hematopoietic stem cell transplantation (synHSCT), and was evident even in distant tumors that were not transduced with the IFN-α vector. The intratumoral delivery of the IFN-α gene promoted the maturation of CD11c(+) cells in the tumors and effectively augmented the antigen-presentation capacity of the cells. An analysis of the cytokine profile showed that the CD11c(+) cells in the treated tumors secreted a large amount of immune-stimulatory cytokines including interleukin (IL)-6. The CD11c(+) cells rescued effector T-cell proliferation from regulatory T-cell-mediated suppression, and IL-6 may have a dominant role in this phenomenon. The intratumoral IFN-α gene transfer creates an environment strongly supporting the enhancement of antitumor immunity in reconstituted lymphopenic recipients through the induction of tumor-specific immunity and suppression of immunotolerance.

Immunity to Trop-1, a newly identified breast cancer antigen, inhibits the growth of breast cancer in mice

This study describes the immunotherapeutic properties of vaccines that encode tumor-associated calcium signal transducer-1 (Trop-1), a newly identified breast cancer antigen, in mice with breast cancer. Previously we found that Trop-1 was over-expressed in cellular breast cancer vaccines that were highly enriched for cells that induced therapeutic CTL-mediated immune responses in mice with breast cancer, as compared with non-enriched vaccines. In this study, to determine if the expression of Trop-1 by cells in the enriched vaccine was responsible for its therapeutic benefits, an expression plasmid that specified the Trop-1 gene was transfected into the LM fibroblast cells, which was then used as a vaccine. To augment their immunogenic properties, the fibroblasts were genetically modified before Trop-1 DNA-transfer to secrete IL-2 and to express allogeneic MHC class I H-2K(b)-determinants. Mice with established breast cancer treated solely by immunization with fibroblasts modified to express Trop-1 developed CD8(+) cell-mediated immunity to the breast cancer cells. The immunity was sufficient to prolong the survival of mice with established breast cancer. In some instances, the immunity was sufficient to result in rejection of the tumor; the mice remained tumor free more than 60 days.

Increased plasma-immune cytokines throughout the high-dose melphalan-induced lymphodepletion in patients with multiple myeloma: a window for adoptive immunotherapy

High-dose melphalan (HDM) followed by autologous stem cell transplantation (ASCT) is a standard treatment for patients with multiple myeloma. However, lymphocyte reconstitution is impaired after HDM. Recent work has suggested that the lymphopenia period occurring after various immunosuppressive or chemotherapy treatments may provide an interesting opportunity for adoptive antitumor immunotherapy. The objective of this study was to determine an immunotherapy window after HDM and ASCT, evaluating T cell lymphopenia, and measuring circulating immune cytokine concentrations in patients with multiple myeloma. The counts of T cell subpopulations reached a nadir at day 8 post-ASCT (day 10 post-HDM) and recovered by day 30. IL-6, IL-7, and IL-15 plasma levels increased on a median day 8 post-ASCT, respectively, 35-fold, 8-fold, and 10-fold compared with pre-HDM levels (p < or = 0.05). The increases in IL-7 and IL-15 levels were inversely correlated to the absolute lymphocyte count, unlike monocyte or myeloid counts. Furthermore, we have shown that CD3 T cells present in the ASC graft are activated, die rapidly when they are cultured without cytokine in vitro, and that addition of IL-7 or IL-15 could induce their survival and proliferation. In conclusion, the early lymphodepletion period, occurring 4-11 d post-HDM and ASCT, is associated with an increase of circulating immune cytokines and could be an optimal window to enhance the survival and proliferation of polyclonal T cells present in the ASC autograft and also of specific antimyeloma T cells previously expanded in vitro.

Intratumoral interferon-alpha gene transfer enhances tumor immunity after allogeneic hematopoietic stem cell transplantation

One of the major challenges in the treatment of solid cancers by allogenic hematopoietic stem cell transfer (alloHSCT) is the specific enhancement of antitumor immunity. Interferon (IFN) is a cytokine with pleiotropic biological functions including an immunomoduration, and our preclinical studies have shown that an intratumoral IFN-alpha gene transfer induced strong local tumor control and systemic tumor-specific immunity. In the present study, we examined whether the IFN-alpha gene transfer could enhance recognition of tumor-associated antigens by donor T cells and augment the antitumor activity of alloHSCT. First, when a mouse IFN-alpha adenovirus vector (Ad-mIFN) was injected into subcutaneous xenografts of syngeneic renal and colon cancer cells, tumor growth was significantly suppressed in a dose-dependent manner. A significant tumor cell death and infiltration of immune cells was recognized in the Ad-mIFN-injected tumors, and the dendritic cells isolated from the tumors showed a strong Th1-oriented response. The antitumor effect of Ad-mIFN was then examined in a murine model of minor histocompatibility antigen-mismatched alloHSCT. The intratumoral IFN-alpha gene transfer caused significant tumor suppression in the alloHSCT recipients, and this suppression was evident not only in the gene-transduced tumors but also in simultaneously inoculated distant tumors which did not receive the vector injection. A cytotoxicity assay showed specific tumor cell lysis by donor T cells responding to IFN-alpha. Graft-versus-host disease was not exacerbated serologically or clinically in the mice treated with IFN-alpha. This combination strategy deserves evaluation in future clinical trials for human solid cancers.