Current concepts of tumor-infiltrating lymphocytes in human malignancies

IL-12 delivered intratumorally by multilamellar liposomes reactivates memory T cells in human tumor microenvironments

Using a novel loading technique, IL-12 is reported here to be efficiently encapsulated within large multilamellar liposomes. The preclinical efficacy of the cytokine loaded liposomes to deliver IL-12 into human tumors and to reactive tumor-associated T cells in situ is tested using a human tumor xenograft model. IL-12 is released in vivo from these liposomes in a biologically active form when injected into tumor xenografts that are established by the subcutaneous implantation of non-disrupted pieces of human lung, breast or ovarian tumors into immunodeficient mice. The histological architecture of the original tumor tissue, including tumor-associated leukocytes, tumor cells and stromal cells is preserved anatomically and the cells remain functionally responsive to cytokines in these xenografts. The local and sustained release of IL-12 into the tumor microenvironment reactivates tumor-associated quiescent effector memory T cells to proliferate, produce and release IFN-gamma resulting in the killing of tumor cells in situ. Very little IL-12 is detected in the serum of mice for up to 5 days after an intratumoral injection of the IL-12 liposomes. We conclude that IL-12 loaded large multilamellar liposomes provide a safe method for the local and sustained delivery of IL-12 to tumors and a therapeutically effective way of reactivating existing tumor-associated T cells in human solid tumor microenvironments. The potential of this local in situ T cell re-stimulation to induce a systemic anti-tumor immunity is discussed.

Immunomodulation in endometrial cancer

Endometrial cancer is the most frequent gynecological cancer and the fourth most common cancer in women in the developed world. Over the last decade, immunotherapy has been the focus of intense investigation as a form of cancer treatment whereby the treatment initiates a host immune response ultimately eradicating the tumor. It has been suggested that in endometrial cancer and many other forms of cancer, immunosuppression poses a significant obstacle at inducing antitumor immunity by immunotherapy. This review will look at the different studies that have identified immunomodulation of T cells, cytokines and macrophages, and regulation of apoptotic and angiogenic factors in endometrial cancer patients that may contribute to the inefficiency of immunotherapy.

B7-H1 on myeloid-derived suppressor cells in immune suppression by a mouse model of ovarian cancer

Myeloid-derived suppressor cells (MDSCs) accumulate in tumor-bearing hosts and are associated with immune suppression. Here, we described high level of expression of B7-H1 (CD274), PD-1 (CD279) and CTLA4 (CD152) by Gr-1(+)CD11b(+) MDSCs obtained from both ascites and spleens of mice bearing the 1D8 ovarian carcinoma, whereas B7-DC (CD273), CD40 and CD86 were absent. In contrast, B7-H1, PD-1 and CTLA-4 expression was not detected on Gr-1(+)CD11b(+) cells from naive mice. Expression of B7-H1 by Gr-1(+)CD11b(+) cells from naive mice could be induced by co-culture with 1D8 ovarian carcinoma cells. Gr-1(+)CD11b(+) cells derived from 1D8 tumor-bearing mice markedly suppressed antigen-specific immune responses, whereas Gr-1(+)CD11b(+) cells from naive mice did not. siRNA-mediated knockdown of B7-H1 in Gr-1(+)CD11b(+) cells of 1D8 tumor-bearing mice alleviated suppression of antigen-specific immune responses. Suppression of antigen-specific immune responses via B7-H1 on Gr-1(+)CD11b(+) myeloid cells was mediated by CD4(+)CD25(+) Foxp3(+) T regulatory cells and required PD-1. Antibody blockade of either B7-H1 or PD-1 retarded the growth of 1D8 tumor in mice. This suggests that expression of B7-H1 on Gr-1(+)CD11b(+) myeloid cells triggered by the 1D8 mouse model of ovarian carcinoma suppresses antigen-specific immunity via interaction with PD-1 on CD4(+)CD25(+) Foxp3(+) regulatory T cells.

Tumor escape mechanism governed by myeloid-derived suppressor cells

T-cell nonresponsiveness is a critical factor in immune escape and myeloid-derived suppressor cells play a major role in organizing this phenomenon. Recent findings indicate that myeloid-derived suppressor cells can induce antigen-specific CD8(+) T-cell tolerance through a posttranslation mechanism which involves modification (nitration) of CD8 and the T-cell receptor itself on the T-cell surface. Elucidation of this mechanism of T-cell tolerance offers new opportunities for therapeutic corrections of immune escape in cancer.

Pathobiological features of breast tumours in the State of Kuwait: a comprehensive analysis

Background

Breast cancer accounts for 30.3% of all cancer types in Kuwaiti women. Death occurs in approximately 43% of these patients. Our goal was to conduct a comprehensive analysis of the pathobiological characteristics of the tumours in an attempt to determine any particular trend that could be present.

Methods

One hundred and sixty-six cases were included in this study. All the pathology reports and paraffin blocks pertaining to these cases were collected. Four micrometer sections were taken from each block, and immunostaining against Her-2, ER, and PgR was performed. Both the proportion and intensity of immunostaining were scored according to the Allred's method, and typing of the tumour was done according the WHO criteria regarding tumour classification. Grading of invasive carcinomas was done according to the modified Bloom-Richardson-Elston's method, and tumour stage was determined according to the criteria set by the American Joint Committee on Cancer.

Results

The mean age of the patients below 55 years was 40, as compared to 68 for those above 55 (p < 0.0001). More than half of the cases were in the right breast, and were surgically treated by total mastectomy with axillary clearance. The majority of the tumours had irregular (stellate) margins, was invasive, and had a surrounding breast tissue of adenosis or fibrocystic type. Their mitotic index was 10–20 or >20 with a marked to moderate nuclear pleomorphism. They were mostly grade II or III, sized 2–5 or > 5 cm, had absent or scanty tumour lymphocytes, and were stage II or III. The in situ tumours were mainly ductal carcinoma (DCIS) of which comedo and cribriform were the major histological subtypes. The major histological subtypes of the invasive tumours were ductal-not otherwise specified, lobular, and tubular/cribriform. In this study, we also found a significant (p < 0.05) association between over expression of Her-2, lack of expression of ER and some of the characteristics mentioned above.

Conclusion

Breast cancer in Kuwait seems to be more aggressive than what is currently seen in Europe, North America, Australia, and parts of Asia. Further investigations regarding the features observed in this study need to be performed.

Knockdown of RCAS1 expression by RNA interference recovers T cell growth and proliferation

Receptor binding cancer antigen expressed on SiSo cells (RCAS1), a tumor-associated antigen, was expressed in various malignant tissues. It is involved in the tumor immune escape. Here, we reported the evidence that knockdown of RCAS1 expression by RNA interference can recovers T cell growth and proliferation. We designed a small hairpin RNA to knockdown RCAS1 expression in MCF-7 cells effectively. Adding RCAS1 protein resulted in a reduced T cell growth rate, an increased T cell apoptosis ratio, the higher activity of Caspase-3 proteases, and decreased IFN-gamma secretion. The suppression of RCAS1 expression effectively recover T cell proliferation, reduce apoptosis and partially reverse the T cell function of IFN-gamma secretion.

Spontaneous mammary tumors differ widely in their inherent sensitivity to adoptively transferred T cells

Immunotherapy of cancer can lead to the selection of antigen loss variants, which provides strong rationale to target oncogenes that are essential for tumor growth or viability. To investigate this concept, we tagged the HER2/neu oncogene with epitopes from ovalbumin to confer recognition by T-cell receptor transgenic CD8(+) (OT-I) and CD4(+) (OT-II) T cells. Transgenic mice expressing neu(OT-I/OT-II) developed mammary adenocarcinomas at 6 to 10 months of age. Adoptively transferred naive OT-I cells (with or without OT-II cells) proliferated vigorously on encountering neu(OT-I/OT-II)-expressing tumors. This was followed by the complete regression of 37% of tumors, whereas others showed partial/stable responses (40%) or progressive disease (23%). Those tumors undergoing complete regression never recurred. In mice with multiple primary tumors, simultaneous regressions and nonregressions were often seen, indicating that immune evasion occurred at a local rather than systemic level. The majority of nonregressing tumors expressed Neu(OT-I/OT-II) and MHC class I, and many avoided rejection through a profound block to T-cell infiltration. Thus, T cells directed against an essential oncogene can permanently eradicate a subset of spontaneous, established mammary tumors. However, in other tumors, local barriers severely limit the therapeutic response. To maximize the efficacy of immunotherapy against spontaneous cancers, predictive strategies that take into account the heterogeneity of the tumor microenvironment will be required.

Intratumoral balance of regulatory and cytotoxic T cells is associated with prognosis of hepatocellular carcinoma after resection

PURPOSE

To investigate the prognostic value of tumor-infiltrating lymphocytes (TILs), especially regulatory T cells (Tregs), in hepatocellular carcinoma (HCC) patients after resection.

PATIENTS AND METHODS

CD3+, CD4+, CD8+, Foxp3-positive, and granzyme B-positive TILs were assessed by immunohistochemistry in tissue microarrays containing HCC from 302 patients. Prognostic effects of low- or high-density TIL subsets were evaluated by Cox regression and Kaplan-Meier analysis using median values as cutoff.

RESULTS

CD3+, CD4+, CD8+ TILs were associated with neither overall survival (OS) nor disease-free survival (DFS). The presence of low intratumoral Tregs in combination with high intratumoral activated CD8+ cytotoxic cells (CTLs), a balance toward CTLs, was an independent prognostic factor for both improved DFS (P = .001) and OS (P < .0001). Five-year OS and DFS rates were only 24.1% and 19.8% for the group with intratumoral high Tregs and low activated CTLs, compared with 64.0% and 59.4% for the group with intratumoral low Tregs and high activated CTLs, respectively. Either intratumoral Tregs alone (P = .001) or intratumoral activated CTLs (P = .001) alone is also an independent predictor for OS. In addition, high Tregs density was associated with both absence of tumor encapsulation (P = .032) and presence of tumor vascular invasion (P = .031).

CONCLUSION

Tregs are associated with HCC invasiveness, and intratumoral balance of regulatory and cytotoxic T cells is a promising independent predictor for recurrence and survival in HCC. A combination of depletion of Tregs and concomitant stimulation of effector T cells may be an effective immunotherapy to reduce recurrence and prolong survival after surgery.

Immune concept of human papillomaviruses and related antigens in local cancer milieu of human cervical neoplasia

It is presently the right time for clarifying human papillomavirus (HPV)-associated cellular immunity and clinical implications before global HPV vaccination programs begin. Infection with oncogenic HPV associates with the progression of cervical neoplasia. Both cellular and humoral immune responses are essential for the clearance of HPV-associated cervical lesions. There is increasing evidence that the immune system plays a pivotal role in determining the outcome of HPV infection. Viruses and associated neoplastic cells are proposed to have evolved mechanisms to avoid immune attack. T-cell-mediated immune responses against oncogenic HPV are believed to play a central role in cervical carcinogenesis. The presence of HPV-specific cytotoxic T lymphocytes (CTL) in a majority of human cervical cancer patients provides an approach for further study of their functional role in modulating this malignancy. Tumor-infiltrating lymphocytes (TIL) develop as manifestations of the recognition and defense against malignant cells by the host immune system. Cancer cells may overcome immune surveillance, either by downregulating the proliferation of HPV-specific CTL, or altering the effector compositions of immune cells against HPV infections. TIL in the tumor microenvironment can be functionally inhibited and lose the ability of clonal proliferation as a result of depressed expression of IL-2Ralpha. The upregulation of inhibitory signaling relates to the modulation of the virus- and/or tumor-specific immune responses. Alteration of host genetic susceptibility may also lead to abnormal immune response as a general genomic instability resulting from virus persistence. Induction of HPV-specific immune responses is anticipated as an intimate point for the treatment of cervical neoplasia.

Selective targeting and potent control of tumor growth using an EphA2/CD3-Bispecific single-chain antibody construct

The EphA2 receptor tyrosine kinase is frequently overexpressed and functionally altered in malignant cells and thus provides opportunities for selective targeting of tumor cells. We describe here the development of a novel, bispecific single-chain antibody (bscAb) referred to as bscEphA2xCD3. This molecule simultaneously targets EphA2 on tumor cells and the T-cell receptor/CD3 complex on T cells and possesses structural and functional characteristics of the recently developed BiTE technology. An EphA2-specific single-chain antibody was selected for recognition of an epitope that is preferentially exposed on malignant cells based on the concept of epitope exclusion; this was fused to a CD3-specific single-chain antibody to generate bscEphA2xCD3. The resultant bscAb redirected unstimulated human T cells to lyse EphA2-expressing tumor cells both in vitro and in vivo. In separate experiments, efficient tumor cell lysis was achieved in vitro at drug concentrations <or=1 microg/mL, at a low T-cell effector-to-tumor target cell ratio (1:1), and with tumor cells that possess few available binding sites (2,400 per cell) for bscEphA2xCD3. Time-lapsed microscopy revealed potent cytotoxic activity of bscEphA2xCD3-activated T cells against monolayers of malignant cells but not against monolayers of nontransformed EphA2-positive cells except at the edges of the monolayer where the target epitope was exposed. BscEphA2xCD3 was also efficacious in human xenograft mouse models modified to show human T-cell killing of tumors. Together, our results reveal opportunities for redirecting the potent activity of cytotoxic T cells towards tumor cells that express selectively accessible epitopes and establish EphA2-specific bscAb molecules as novel and potent therapeutics with selectivity for tumor cells.

NK Cells and Cancer

In this review, we overview the main features and functions of NK cells, focusing on their role in cell-mediated immune response to tumor cells. In parallel, we discuss the information available in the field of NK cell receptors and offer a wide general overview of functional aspects of cell targeting and killing, focusing on the recent acknowledgments on the efficacy of NK cells after cytokine and mAb administration in cancer therapy. Since efficacy of NK cell-based immunotherapy has been proven in KIR-mismatch regimens or in TRAIL-dependent apoptosis, the ability to manipulate the balance of activating and inhibitory receptors on NK cells and of their cognate ligands, as well as the sensitivity of tumor cells to apoptosis, opens new perspectives for NK cell-based immunotherapy.

Immune cell migration as a means to control immune privilege: lessons from the CNS and tumors

Certain organs, such as the brain, eye, and gonads, are particularly sensitive to damage by inflammation. Therefore, these tissues have developed unique immunological properties that curtail inflammatory responses, a phenomenon termed immune privilege. In addition, by co-opting some of the regulatory cues operant in immune privilege in normal organs, tumors can evade immunosurveillance. While many different mechanisms contribute to immune privilege, there is evidence that leukocyte migration is an important checkpoint in its control. This hypothesis is based on the fact that leukocyte entry into these organs is restricted by physical barriers and that the collapse of these obstacles marks a critical step in the development of inflammatory/autoimmune disease at these sites. Numerous studies in a variety of experimental systems have characterized the molecular and cellular mechanisms involved in leukocyte homing to immune-privileged organs. Recently, two-photon microscopy has revealed critical insights into the events occurring in the extravascular space of immune-privileged organs, including locomotion patterns and interactive behavior of leukocytes in the interstitial space. Here, we review our current understanding of immune cell migration to and within immune-privileged organs and highlight how this knowledge may be exploited for immunotherapeutic purposes.

Memory T cells in human tumor and chronic inflammatory microenvironments: sleeping beauties re-awakened by a cytokine kiss

Human tumors often progress and spread in spite of the presence of large numbers of CD4+ and CD8+ T cells with activated or memory cell phenotypes. The T cells in the microenvironment of human lung tumors fail to be activated in response to stimulation via the T cell receptor and CD28 under conditions that fully activate T cells derived from the peripheral blood of the cancer patients. A combination of regulatory mechanisms which are also observed in a variety of different chronic inflammatory conditions may contribute to the T cell unresponsiveness, and to their inability to respond to and kill tumor cells. The non-responsiveness of memory T cells isolated from human lung tumors and non-malignant chronic inflammatory tissues can be reversed in vitro by a brief pulse with IL-12, and the local and sustained release of exogenous IL-12 into the microenvironment of human tumor xenografts in SCID mice re-activates the tumor-associated T cells in situ. In the later case, the T cells proliferate, secrete interferon-gamma and initiate a cascade of events that culminate in the eradication of tumor cells from the xenograft. In transplantable and spontaneously developing tumors of mice the injection of a single tumor nodule with IL-12 loaded biodegradable microspheres activates tumor-associated T cells to kill tumor cells in situ, and provokes a systemic anti-tumor response that results in the eradication of distant metastatic tumor nodules that are not treated with the cytokine. These mice exhibit a systemic tumor specific immunity as they resist a second challenge with the same (but not a different) tumor. These findings suggest that it will be possible to provoke a systemic anti-tumor immunity in cancer patients by the direct injection of IL-12 loaded biodegradable microspheres or liposomes to locally deliver very low but sustained doses of IL-12 into a single tumor site. This strategy which is based upon the ability of IL-12 to re-activate tumor-associated T cells is termed in situ tumor vaccination.

Membrane-associated TGF-beta1 inhibits human memory T cell signaling in malignant and nonmalignant inflammatory microenvironments

TGF-beta1 is present on cells derived from the microenvironment of human lung tumors and nonmalignant inflammatory tissues. We establish that this cell-associated cytokine mediates hyporesponsiveness of the memory T cells in these microenvironments in situ by blocking TCR signaling. T cells derived from these tissues failed to translocate NF-kappaB to the nucleus in response to CD3 + CD28 cross-linking. This nonresponsiveness was reversed by an anti-TGF-beta1-neutralizing Ab. Refractoriness of the memory T cells to TCR activation was also reversed by the removal of TGF-beta1 by briefly pulsing the cells in a low pH buffer. Addition of exogenous TGF-beta1 to eluted T cells re-established their nonresponsive state. Neither TGF-beta1, anti-TGF-beta1 Ab, nor low pH affected TCR signaling potential of peripheral blood T cells. We conclude that TGF-beta1 mediates a physiologically relevant regulatory mechanism, selective for memory T cells present in the tumor microenvironment and nonmalignant chronic inflammatory tissues.

Comparison of RCAS1 and metallothionein expression and the presence and activity of immune cells in human ovarian and abdominal wall endometriomas

BACKGROUND

The coexistence of endometrial and immune cells during decidualization is preserved by the ability of endometrial cells to regulate the cytotoxic immune activity and their capability to be resistant to immune-mediated apoptosis. These phenomena enable the survival of endometrial ectopic cells. RCAS1 is responsible for regulation of cytotoxic activity. Metallothionein expression seems to protect endometrial cells against apoptosis. The aim of the present study was to evaluate RCAS1 and metallothionein expression in human ovarian and scar endometriomas in relation to the presence of immune cells and their activity.

METHODS

Metallothionein, RCAS1, CD25, CD69, CD56, CD16, CD68 antigen expression was assessed by immunohistochemistry in ovarian and scar endometriomas tissue samples which were obtained from 33 patients. The secretory endometrium was used as a control group (15 patients).

RESULTS

The lowest metallothionein expression was revealed in ovarian endometriomas in comparison to scar endometriomas and to the control group. RCAS1 expression was at the highest level in the secretory endometrium and it was at comparable levels in ovarian and scar endometriomas. Similarly, the number of CD56-positive cells was lower in scar and ovarian endometriomas than in the secretory endometrium. The highest number of macrophages was found in ovarian endometriomas. RCAS1-positive macrophages were observed only in ovarian endometriomas. CD25 and CD69 antigen expression was higher in scar and ovarian endometriomas than in the control group.

CONCLUSION

The expression of RCAS1 and metallothionein by endometrial cells may favor the persistence of these cells in ectopic localization both in scar following cesarean section and in ovarian endometriosis.