Adoptive cell therapy of prostate cancer using female mice-derived T cells that react with prostate antigens

Effects of female bone marrow transplantation on male reproductive organs

Graft-versus-host disease (GVHD), an adverse effect after bone marrow transplantation (BMT), may affect male reproductive function. It is hypothesized that a sex-mismatched BMT induces GVHD in male reproductive organs because female immune cells are not immunologically tolerant to specific antigens of the male organs. However, this hypothesis has not been experimentally verified using male (M) recipient animals following BMT from the female (F) donors. Therefore, the aim of the present study is to examine whether the female BMT to males (F→M group) induces some GVHD reactions in the testis and the other male reproductive organs. The results showed that no inflammation was found in recipients of the male BMT to males (M→M group), whereas significant inflammatory cell responses lasting for at least 4 months were induced in testis, epididymis, prostate and preputial gland in some mice of F→M group. The most severe lesion was found in the preputial gland, in which lymphocytic inflammation was accompanied by loss of glandular acini, thickening of the interstitum and increased cytokines such as TNF-α and IFN-γ. Western blot analyses revealed that sera from the F→M group reacted with various antigens of the male reproductive organs. These results indicate that transplanted female immune cells may recognize the male reproductive organs as immunologically foreign ones and induce chronic GVHD, which may affect male reproductive function.

Sex dimorphism in the tumor microenvironment - From bench to bedside and back

Cancer represents a significant cause of death and suffering in both the developed and developing countries. Key underlying issues in the mortality of cancer are delayed diagnosis and resistance to treatments. However, improvements in biomarkers represent one important step that can be taken for alleviating the suffering caused by malignancy. Precision-based medicine is promising for revolutionizing diagnostic and treatment strategies for cancer patients worldwide. Contemporary methods, including various omics and systems biology approaches, as well as advanced digital imaging and artificial intelligence, allow more accurate assessment of tumor characteristics at the patient level. As a result, treatment strategies can be specifically tailored and adapted for individual and/or groups of patients that carry certain tumor characteristics. This includes immunotherapy, which is based on characterization of the immunosuppressive tumor microenvironment (TME) and, more specifically, the presence and activity of immune cell subsets. Unfortunately, while it is increasingly clear that gender strongly affects immune regulation and response, there is a knowledge gap concerning differences in sex-specific immune responses and how these contribute to the immunosuppressive TME and the response to immunotherapy. In fact, sex dimorphism is poorly understood in cancer progression and is typically ignored in current clinical practice. In this review, we aim to survey the available literature and highlight the existing knowledge gap in order to encourage further studies that would contribute to understanding both gender-biased immunosuppression in the TME and the driver of tumor progression towards invasive and metastatic disease. The review highlights the need to include sex optimized/genderized medicine as a new concept in future medicine cancer diagnostics and treatments.

CD47 deficiency in tumor stroma promotes tumor progression by enhancing angiogenesis

CD47 is a transmembrane protein that functions as a receptor for thrombospondin-1 (TSP1) and a ligand for inhibitory receptor signal-regulatory protein-α (SIRPα). Blocking the interaction between CD47 on tumor cells and SIRPα on macrophages has been shown to induce antitumor responses. Here we investigated the role of CD47 expression in tumor stroma in tumorigenesis by comparing tumor growth in wild-type (WT) and CD47-deficient mice after subcutaneous injection of syngeneic prostate cancer cells. We found that CD47 deficiency in tumor stromal endothelial cells enhances angiogenesis, leading to suppressed tumor necrosis formation and accelerated tumor progression. Tumors from CD47-deficient mice also showed improved vascular integrity and stability, as well as increased expression of vascular endothelial growth factor (VEGF)-A and VEGF receptor 2 (VEGFR2) compared to those from WT mice. Moreover, reduced macrophage recruitment, likely due to decreased TSP1 production, was detected in tumors from CD47-deficient mice. Our results indicate that although treatment with antibody against CD47 induces antitumor immune responses by blocking the inhibitory CD47-SIRPα signaling, this treatment may also potentially promote tumor progression by blocking CD47 signaling in tumor stromal endothelial cells.

Novel prostate cancer immunotherapy with a DNA-encoded anti-prostate-specific membrane antigen monoclonal antibody

Prostate-specific membrane antigen (PSMA) is expressed at high levels on malignant prostate cells and is likely an important therapeutic target for the treatment of prostate carcinoma. Current immunotherapy approaches to target PSMA include peptide, cell, vector or DNA-based vaccines as well as passive administration of PSMA-specific monoclonal antibodies (mAb). Conventional mAb immunotherapy has numerous logistical and practical limitations, including high production costs and a requirement for frequent dosing due to short mAb serum half-life. In this report, we describe a novel strategy of antibody-based immunotherapy against prostate carcinoma that utilizes synthetic DNA plasmids that encode a therapeutic human mAb that target PSMA. Electroporation-enhanced intramuscular injection of the DNA-encoded mAb (DMAb) plasmid into mice led to the production of functional and durable levels of the anti-PSMA antibody. The anti-PSMA produced in vivo controlled tumor growth and prolonged survival in a mouse model. This is likely mediated by antibody-dependent cellular cytotoxicity (ADCC) effect with the aid of NK cells. Further study of  this novel approach for treatment of human prostate disease and other malignant conditions is warranted.

Phase I Trial of Anti-PSMA Designer CAR-T Cells in Prostate Cancer: Possible Role for Interacting Interleukin 2-T Cell Pharmacodynamics as a Determinant of Clinical Response

BACKGROUND

Chimeric antigen receptor (CAR)-modified "designer" T cells (dTc, CAR-T) against PSMA selectively target antigen-expressing cells in vitro and eliminate tumors in vivo. Interleukin 2 (IL2), widely used in adoptive therapies, was proven essential in animal models for dTc to eradicate established solid tumors.

METHODS

Patients under-went chemotherapy condi-tion-ing, followed by dTc dosing under a Phase I escalation with continuous infusion low dose IL2 (LDI). A target of dTc escalation was to achieve ≥20% engraftment of infused activated T cells.

RESULTS

Six patients enrolled with doses prepared of whom five were treated. Patients received 10(9) or 10(10) autologous T cells, achieving expansions of 20-560-fold over 2 weeks and engraftments of 5-56%. Pharmacokinetic and pharmacodynamic analyses established the impact of conditioning to promote expansion and engraftment of the infused T cells. Unexpectedly, administered IL2 was depleted up to 20-fold with high engraftments of activated T cells (aTc) in an inverse correlation (P < 0.01). Clinically, no anti-PSMA toxicities were noted, and no anti-CAR reactivities were detected post-treatment. Two-of-five patients achieved clinical partial responses (PR), with PSA declines of 50% and 70% and PSA delays of 78 and 150 days, plus a minor response in a third patient. Responses were unrelated to dose size (P = 0.6), instead correlating inversely with engraftment (P = 0.06) and directly with plasma IL2 (P = 0.03), suggesting insufficient IL2 with our LDI protocol to support dTc anti-tumor activity under optimal (high) dTc engraftments.

CONCLUSIONS

Under a Phase I dose escalation in prostate cancer, a 20% engraftment target was met or exceeded in three subjects with adequate safety, leading to study conclusion. Clinical responses were obtained but were suggested to be restrained by low plasma IL2 when depleted by high levels of engrafted activated T cells. This report presents a unique example of how the pharmaco-dynamics of "drug-drug" interactions may have a critical impact on the efficacy of their co-application. A new Pilot/Phase II trial is planned to test moderate dose IL2 (MDI) together with high dTc engraftments for anticipated improved therapeutic efficacy. Prostate 76:1257-1270, 2016. © 2016 Wiley Periodicals, Inc.

Over-expressing transporters associated with antigen processing increases antitumor immunity response in prostate cancer

As we know, prostate cancer down-regulates expression of HLA-1 Antigen Processing Machinery (APM) and has defects in the antigen presentation pathway. In vitro, the prostate cancer cell (PC-3 cells) infected with Lentivirus TAP1 can efficiently over-express TAP1 and Tapasin, and HLA-1 was also up-regulated on the surface of the infected cells. The lentivirus TAP1 infection increased the apoptosis rate of PC-3 cells. In addition, with the co-cluture PC-3 cells and lymphocytes, TAP1 augmented the expression of CD3⁺CD8⁺CD38⁺ T cell. Importantly, administration of Lentivirus TAP1 to prostate cancer cells in a xenograft mouse model can prolong survival and increase the CD4⁺ T cells, and CD8⁺ T cells as well as decrease Foxp3⁺ T cells in the tumor microenvironment. In summary, a recombinant lentivirus expressing TAP1 can effectively increase prostate cancer tumor-specific immune response.

Repertoire enhancement with adoptively transferred female lymphocytes controls the growth of pre-implanted murine prostate cancer

BACKGROUND

In prostate cancer, genes encoding androgen-regulated, Y-chromosome-encoded, and tissue-specific antigens may all be overexpressed. In the adult male host, however, most high affinity T cells targeting these potential tumor rejection antigens will be removed during negative selection. In contrast, the female mature T-cell repertoire should contain abundant precursors capable of recognizing these classes of prostate cancer antigens and mediating effective anti-tumor immune responses.

METHODOLOGY/PRINCIPAL FINDINGS

We find that syngeneic TRAMP-C2 prostatic adenocarcinoma cells are spontaneously rejected in female hosts. Adoptive transfer of naïve female lymphocytes to irradiated male hosts bearing pre-implanted TRAMP-C2 tumor cells slows tumor growth and mediates tumor rejection in some animals. The success of this adoptive transfer was dependent on the transfer of female CD4 T cells and independent of the presence of CD25-expressing regulatory T cells in the transferred lymphocytes. We identify in female CD4 T cells stimulated with TRAMP-C2 a dominant MHC II-restricted response to the Y-chromosome antigen DBY. Furthermore, CD8 T cell responses in female lymphocytes to the immunodominant MHC I-restricted antigen SPAS-1 are markedly increased compared to male mice. Finally, we find no exacerbation of graft-versus-host disease in either syngeneic or minor-antigen mismatched allogeneic lymphocyte adoptive transfer models by using female into male versus male into male cells.

CONCLUSIONS/SIGNIFICANCE

This study shows that adoptively transferred female lymphocytes, particularly CD4 T cells, can control the outgrowth of pre-implanted prostatic adenocarcinoma cells. This approach does not significantly worsen graft-versus-host responses suggesting it may be viable in the clinic. Further, enhancing the available immune repertoire with female-derived T cells may provide an excellent pool of prostate cancer reactive T cells for further augmentation by combination with either vaccination or immune regulatory blockade strategies.

Polysaccharide-K augments docetaxel-induced tumor suppression and antitumor immune response in an immunocompetent murine model of human prostate cancer

Advanced castration-resistant prostate cancer has high mortality rates and limited treatment options. Novel therapies are needed to better contend with this disease. Polysaccharide-K^® (PSK), an extract of the mushroom Trametes versicolor, has immunomodulatory and tumor suppressive activities. PSK is used in Asia as a cancer immunotherapy. However, its benefit in combination with taxanes for prostate cancer is unknown. We examined whether PSK would enhance docetaxel-induced apoptosis and augment anti-tumor immune responses in orthotopic tumors using transgenic adenocarcinoma of the mouse prostate (TRAMP)-C2-bearing mice. Combining PSK with docetaxel induced significantly higher tumor suppression than either treatment alone (p<0.05), including a reduction in tumor proliferation and enhanced apoptosis. Combined PSK and docetaxel treatment led to a lower decrease in number of white blood cells than docetaxel alone, an effect accompanied by increased numbers of tumor-infiltrating CD4⁺ and CD8⁺ T cells. PSK with or without docetaxel significantly enhanced mRNA expression of IFN-γ compared to control, but did not significantly alter T-regulatory FoxP3 mRNA expression in tumors. PSK also augmented docetaxel-induced splenic natural killer cell cytolytic activity against YAC-1 target cells (p=0.045). This study is the first to show that PSK enhances docetaxel-induced prostate cancer tumor suppression, apoptosis and antitumor responses.