IDO and outcomes in ovarian cancer. Gynecol Oncol. 2009;115:179-180. [PMID: 19822256 DOI: 10.1016/j.ygyno.2009.09.017]

Review of 10 years of research on breast cancer patients: Focus on indoleamine 2,3-dioxygenase

Therapeutic manipulation of the immune system in cancer has been an extensive area of research in the field of oncoimmunology. Immunosuppression regulates antitumour immune responses. An immunosuppressive enzyme, indoleamine 2,3-dioxygenase (IDO) mediates tumour immune escape in various malignancies including breast cancer. IDO upregulation in breast cancer cells may lead to the recruitment of regulatory T (T-regs) cells into the tumour microenvironment, thus inhibiting local immune responses and promoting metastasis. Immunosuppression induced by myeloid derived suppressor cells activated in an IDO-dependent manner may enhance the possibility of immune evasion in breast cancer. IDO overexpression has independent prognostic significance in a subtype of breast cancer of emerging interest, basal-like breast carcinoma. IDO inhibitors as adjuvant therapeutic agents may have clinical implications in breast cancer. This review proposes future prospects of IDO not only as a therapeutic target but also as a valuable prognostic marker for breast cancer.

IDO1: An important immunotherapy target in cancer treatment

Indoleamine 2,3-dioxigenase 1 (IDO1) acts in pathogenic inflammatory processes and engender immune tolerance to tumor antigens. IDO1 can decrease the tryptophan and produce a series of toxic kynurenine metabolites to promote the immune toleration via GCN2 pathway, mTOR pathway, toxic effect of kynurenine and favoring differentiation of Tregs. IDO1 can be induced in most human cells, especially APCs and cancer cells through canonical and non-canonical NF-κB and Jak/STAT pathways, as well as PKC and TGF-β signaling pathways. A series of human cancers over-express IDO1 in a constitutive way. Thus, IDO1 is likely to be an attractive target for developing inhibitors of tumor treatments. Many preclinical and clinical trials have been underway and suggest that IDO1 inhibitor maybe an effective tool against a wide range of cancers. However, the IDO1 inhibitor alone had been verified that to be disappointment in achieving effective antitumor efficacy. Concentrating on its molecular mechanism in immune toleration and complex environments of cancer, IDO1 inhibitor could cooperate with chemotherapies and other immune target inhibitors to lessen the tumor.

Strong Correlation of Indoleamine 2,3-Dioxygenase 1 Expression with Basal-Like Phenotype and Increased Lymphocytic Infiltration in Triple-Negative Breast Cancer

Indoleamine 2,3-dioxygenase 1 (IDO1) is an immunosuppressive enzyme involved in tumor immune escape. Blockade of the IDO1 pathway is an emerging modality of cancer immunotherapy. Triple-negative breast cancer (TNBC) lacks established therapeutic targets and may be a good candidate for this novel immunotherapeutic agent. The purpose of this study was to evaluate the clinicopathologic characteristics of the IDO1-expressing TNBC subset. A tissue microarray was constructed from 200 patients with TNBC. Immunohistochemistry (IHC) for IDO1 and TNBC molecular subtype-surrogate markers (AR, GCDFP-15, claudin-3, E-cadherin, CK5/6, and EGFR) was performed using this tissue microarray. Real-time polymerase chain reaction was performed to confirm the IDO1 mRNA expression level in 16 fresh-frozen TNBC samples. Two hundred TNBCs were classified into four subtypes based on surrogate IHC results: 22 luminal androgen receptor type (11.0%), 23 claudin-low type (11.4%), 103 basal-like type (51.5%), and 52 mixed type (26.0%). IDO1 positivity (defined as expression of >10% tumor cells) was observed in 37% of all TNBCs. IDO1 IHC expression was well correlated with mRNA expression. IDO1 positivity was significantly associated with smaller tumor size, dense stromal lymphocytic infiltration, and basal-like phenotype; however, it did not affect the patients' prognosis. IDO1 expression in basal-like TNBCs is considered an immune inhibitory signal that counterbalances active immunity and may reflect the high mutational load of these tumors. Our results suggest which patients with TNBC would be more efficaciously treated with IDO1 blockade.

Ovarian cancer molecular pathology

Ovarian cancer (OVC) is the fourth leading cause of cancer mortality among women in Europe and the United States. Its early detection is difficult due to the lack of specificity of clinical symptoms. Unfortunately, late diagnosis is a major contributor to the poor survival rates for OVC, which can be attributed to the lack of specific sets of markers. Aside from patients sharing a strong family history of ovarian and breast cancer, including the BRCA1 and BRCA2 tumor suppressor genes mutations, the most used biomarker is the Cancer-antigen 125 (CA-125). CA-125 has a sensitivity of 80 % and a specificity of 97 % in epithelial cancer (stage III or IV). However, its sensitivity is 30 % in stage I cancer, as its increase is linked to several physiological phenomena and benign situations. CA-125 is particularly useful for at-risk population diagnosis and to assess response to treatment. It is clear that alone, CA-125 is inadequate as a biomarker for OVC diagnosis. There is an unmet need to identify additional biomarkers. Novel and more sensitive proteomic strategies such as MALDI mass spectrometry imaging studies are well suited to identify better markers for both diagnosis and prognosis. In the present review, we will focus on such proteomic strategies in regards to OVC signaling pathways, OVC development and escape from the immune response.

Neem leaf glycoprotein overcomes indoleamine 2,3 dioxygenase mediated tolerance in dendritic cells by attenuating hyperactive regulatory T cells in cervical cancer stage IIIB patients

Tolerogenic dendritic cells (DCs) are a subset of DCs characterized by abundant indoleamine 2,3 dioxygenase (IDO) expressions. IDO may be co-operatively induced in DCs by regulatory T (Tregs) cells and various DC maturation agents. Tregs are markedly amplified in the physiological system of cancer patients, inducing over tolerance in DCs that leads to the hyper accumulation of immunosuppressive IDO in tumor microenvironment, thereby, hampering anti-tumor immunity. Consequently, a major focus of current immunotherapeutic strategies in cancer is to minimize IDO, which is possible by reducing Tregs and using various IDO inhibitors. Neem leaf glycoprotein (NLGP), a natural and nontoxic immunomodulator, demonstrated several unique immunoregulatory activities. Noteworthy activities of NLGP are to mature DCs and to inhibit Tregs. As Tregs are inducer of IDO in DCs and hyperactive Tregs is a hallmark of cancer, we anticipated that NLGP might abrogate IDO induction in DCs by inhibiting Tregs. Evidences are presented here that in a co-culture of DCs and Tregs isolated from cervical cancer stage IIIB (CaCx-IIIB) patients, NLGP does inhibit IDO induction in DCs by curtailing the over expression of Cytotoxic T-Lymphocyte Antigen 4 (CTLA4) on Tregs and concomitantly induces optimal DC maturation. In contrast, in the presence of LPS as maturation agent the DCs displays a tolerogenic profile. This finding suggests the reduction of tolerogenecity of DCs in CaCx-IIIB patients by reducing the IDO pool using NLGP. Accordingly, this study sheds more light on the diverse immunomodulatory repertoire of NLGP.

Dendritic cell engineering for tumor immunotherapy: from biology to clinical translation

Dendritic cells (DCs) are the most potent APCs, with the ability to orchestrate a repertoire of immune responses. DCs play a pivotal role in the initiation, programming and regulation of tumor-specific immune responses, as they are poised to take up, process and present tumor antigens to naive or effector T lymphocytes. Although, to an extent, DC-based immunotherapeutic strategies have successfully induced specific anti-tumor responses in animal models, their clinical efficacy has rarely been translated into the clinic. This article attempts to present a complete picture of recent developments of DC-based therapeutic strategies addressing multiple components of tumor immunoenvironment. It also showcases certain practical intricacies in order to explore novel strategies for providing new impetus to DC-based cancer vaccination.

High expression of indoleamine 2,3-dioxygenase in the tumour is associated with medullary features and favourable outcome in basal-like breast carcinoma

Medullary breast cancer (MBC) is a basal-like breast carcinoma (BLBC) with a favourable outcome, whereas nonmedullary BLBC has a poor prognosis. Tumour infiltrating lymphocytes (TILs) are present in both MBC and BLBC. We hypothesized that the immunosuppressive enzyme indoleamine 2,3-dioxygenase (IDO) could modulate the TILs effects among these tumours and explain their different outcomes. The amount of TILs and IDO expression were analysed using immunohistochemistry (IHC) in 155 BC cases including MBC (n = 17), atypical MBC (n = 13) and non-MBC (n = 125). Messenger RNA expression of the INDO gene, which encodes IDO, was measured in 262 cases from our institution. INDO mRNA expression and histoclinical data of 1,487 BC cases were collected from public databases. IDO immunostaining was present in both neoplastic and stromal cells in 100% of MBC and was associated with histological medullary features among non-MBC cases. There was a significant correlation between IDO positivity and TIL amounts. In our series including mostly grade-3 BC, IDO immunostaining was the most significant marker (p = 0.02) associated with better survival in multivariate analysis. Among our 262 analysed BC cases, INDO mRNA showed significant overexpression in BLBC as compared to luminal A tumours, and in MBC as compared to basal-like non-MBC. In the pooled series of 1,749 BC cases, INDO mRNA was overexpressed in BLBC and was the most significant predictor of better survival in this subtype using multivariate analysis (p = 0.0024). In conclusion, high IDO expression is associated with morphological medullary features and has an independent favourable prognostic value in BLBC.

Immune suppression in tumors as a surmountable obstacle to clinical efficacy of cancer vaccines

Human tumors are usually not spontaneously eliminated by the immune system and therapeutic vaccination of cancer patients with defined antigens is followed by tumor regressions only in a small minority of the patients. The poor vaccination effectiveness could be explained by an immunosuppressive tumor microenvironment. Because T cells that infiltrate tumor metastases have an impaired ability to lyse target cells or to secrete cytokine, many researchers are trying to decipher the underlying immunosuppressive mechanisms. We will review these here, in particular those considered as potential therapeutic targets. A special attention will be given to galectins, a family of carbohydrate binding proteins. These lectins have often been implicated in inflammation and cancer and may be useful targets for the development of new anti-cancer therapies.

Neem leaf glycoprotein partially rectifies suppressed dendritic cell functions and associated T cell efficacy in patients with stage IIIB cervical cancer

Myeloid-derived dendritic cells (DCs) generated from monocytes obtained from stage IIIB cervical cancer (CaCx IIIB) patients show dysfunctional maturation; thus, antitumor T cell functions are dysregulated. In an objective to optimize these dysregulated immune functions, the present study is focused on the ability of neem leaf glycoprotein (NLGP), a nontoxic preparation of the neem leaf, to induce optimum maturation of dendritic cells from CaCx IIIB patients. In vitro NLGP treatment of immature DCs (iDCs) obtained from CaCx IIIB patients results in upregulated expression of various cell surface markers (CD40, CD83, CD80, CD86, and HLA-ABC), which indicates DC maturation. Consequently, NLGP-matured DCs displayed balanced cytokine secretions, with type 1 bias and noteworthy functional properties. These DCs displayed substantial T cell allostimulatory capacity and promoted the generation of cytotoxic T lymphocytes (CTLs). Although NLGP-matured DCs derived from CaCx monocytes are generally subdued compared to those with a healthy monocyte origin, considerable revival of the suppressed DC-based immune functions is noted in vitro at a fairly advanced stage of CaCx, and thus, further exploration of ex vivo and in vivo DC-based vaccines is proposed. Moreover, the DC maturating efficacy of NLGP might be much more effective in the earlier stages of CaCx, where the extent of immune dysregulation is less and, thus, the scope of further investigation may be explored.