IDO expression in breast cancer: an assessment of 281 primary and metastatic cases with comparison to PD-L1

IDO Expression in Cancer: Different Compartment, Different Functionality?

Indoleamine 2,3-dioxygenase 1 (IDO1) is a cytosolic haem-containing enzyme involved in the degradation of tryptophan to kynurenine. Although initially thought to be solely implicated in the modulation of innate immune responses during infection, subsequent discoveries demonstrated IDO1 as a mechanism of acquired immune tolerance. In cancer, IDO1 expression/activity has been observed in tumor cells as well as in the tumor-surrounding stroma, which is composed of endothelial cells, immune cells, fibroblasts, and mesenchymal cells. IDO1 expression/activity has also been reported in the peripheral blood. This manuscript reviews available data on IDO1 expression, mechanisms of its induction, and its function in cancer for each of these compartments. In-depth study of the biological function of IDO1 according to the expressing (tumor) cell can help to understand if and when IDO1 inhibition can play a role in cancer therapy.

Predictive markers for pathological complete response after neo-adjuvant chemotherapy in triple-negative breast cancer

A combination of Sox10 and GATA3 was previously identified as a marker for metastatic triple-negative breast cancer (TNBC), but it is uncertain whether their expression is associated with pathological complete response (pCR) after neoadjuvant chemotherapy (NAC). This study investigates the predictive value of clinicopathological characteristics, as well as protein expression of Sox10, GATA3, p53 and p63, in a consecutive series of TNBC patients treated with NAC. Archived hematoxylin & eosin stained slides of core biopsies and resection specimens from 35 TNBC patients were reviewed. The following clinicopathological characteristics were determined at the biopsy level: age at diagnosis, cancer type, Nottingham grade, lympho-vascular invasion, syncytial growth, necrosis, clear cell differentiation, myxoid peritumor stroma, stromal tumor-infiltrating lymphocytes (sTILs) and presence of an in situ component. The MD Anderson residual cancer burden (RCB) score and corresponding RCB class were determined. Immunohistochemistry for Sox10, p53, GATA3 and p63 was performed at the biopsy level. sTILs, either as a continuous or as a dichotomous variable, were the only parameter that was significantly associated with pCR in univariable and multivariable analyses. Assessment of sTILs showed moderate to good interobserver agreement. High sTILs (≥40%) were significantly associated with increased pCR rates, and this association was observer-independent. This retrospective study of a consecutive community-based cohort of TNBC patients confirms that sTILs are a robust, observer-independent predictor for therapeutic response after NAC. The combination of Sox10, GATA3 and p53 immunoreactivity is unlikely to harbor any predictive value for pCR in TNBC.

Correlation Patterns Among B7 Family Ligands and Tryptophan Degrading Enzymes in Hepatocellular Carcinoma

Mechanisms of dysfunctional T cell immunity in Hepatocellular Carcinoma (HCC) need to be well defined. B7 family molecules provide both co-stimulatory and co-inhibitory signals to T cells while tryptophan degrading enzymes like Indoleamine 2,3 dioxygenase (IDO) and Tryptophan 2,3 Dioxygenase (TDO) mediate tumor immune tolerance. It is necessary to identify their in situ correlative expression, which informs targets for combined immunotherapy approaches. We investigated B7 family molecules, IDO, TDO and immune responsive effectors in the tumor tissues of patients with HCC (n = 28) using a pathway-focused quantitative nanoscale chip real-time PCR. Four best correlative expressions, namely (1) B7-1 & PD-L2, (2) B7-H2 & B7-H3, (3) B7-2 & PD-L1, (4) PD-L1 & PD-L2, were identified among B7 family ligands, albeit they express at different levels. Although TDO expression is higher than IDO, PD-L1 correlates only with IDO but not TDO. Immune effector (Granzyme B) and suppressive (PD-1 and TGF-β) genes correlate with IDO and B7-1, B7-H5, PD-L2. Identification of the in situ correlation of PD-L1, PD-L2 and IDO suggest their cumulative immuno suppressive role in HCC. The distinct correlations among B7-1, B7-2, B7-H2, and B7-H3, correlation of PD-1 with non-cognate ligands such as B7-1 and B7-H5, and correlation of tumor lytic enzyme Granzyme B with IDO and PD-L2 suggest that HCC microenvironment is complexly orchestrated with both stimulatory and inhibitory molecules which together neutralize and blunt anti-HCC immunity. Functional assays demonstrate that both PDL-1 and IDO synergistically inhibit T cell responses. Altogether, the present data suggest the usage of combined immune checkpoint blocking strategies targeting co-inhibitory B7 molecules and IDO for HCC management.

NSABP B-41, a Randomized Neoadjuvant Trial: Genes and Signatures Associated with Pathologic Complete Response

PURPOSE

In NSABP B-41, pathologic complete response (pCR) was associated with prolonged survival among women with HER2-positive operable breast cancer treated with neoadjuvant chemotherapy and lapatinib, trastuzumab, or the combination. We used a large human breast cancer gene expression panel to select candidate prognostic biomarkers for pCR among women treated with trastuzumab in NSABP B-41.

PATIENTS AND METHODS

Eligible patients had a baseline preadjuvant treatment core biopsy sample, known pCR status, and no withdrawal of consent. We analyzed extracted RNA using the human nCounter Breast Cancer 360 gene expression panel. Gene counts were normalized to housekeeping genes and transformed into logarithmic scale with base 2. To screen for candidate genes and metagene signatures prognostic of pCR, we used univariate logistic regression. Variable selection was done by multivariable logistic regression with lasso regularization.

RESULTS

Analyses of data from 130 patients revealed that a composite of gene expression from 19 genes and one gene signature appeared to predict pCR in women with HER2-positive early-stage breast cancer undergoing neoadjuvant chemotherapy with trastuzumab-containing regimens. The identified genes are involved in important pathways such as epithelial-mesenchymal transition, adhesion and migration, estrogen receptor signaling, DNA damage and repair, apoptosis, and proliferation. The AUC from a 10-fold cross-validation on predicting pCR, with these 20 genomic markers in a logistic regression model, was 0.73.

CONCLUSIONS

The expression level of ERBB2, ESR1, and a few other genomic markers was highly predictive of pCR after trastuzumab-containing regimens. These findings need to be validated and calibrated in future studies.

Current Strategies and Novel Therapeutic Approaches for Metastatic Urothelial Carcinoma

Urothelial carcinoma (UC) is a frequent cause of cancer-related deaths worldwide. Metastatic UC has been historically associated with poor prognosis, with a median overall survival of approximately 15 months and a 5-year survival rate of 18%. Although platinum-based chemotherapy remains the mainstay of medical treatment for patients with metastatic UC, chemotherapy clinical trials produced modest benefit with short-lived, disappointing responses. In recent years, the better understanding of the role of immune system in cancer control has led to the development and approval of several immunotherapeutic approaches in UC therapy, where immune checkpoint inhibitors have been revolutionizing the treatment of metastatic UC. Because of a better tumor molecular profiling, FGFR inhibitors, PARP inhibitors, anti-HER2 agents, and antibody drug conjugates targeting Nectin-4 are also emerging as new therapeutic options. Moreover, a wide number of trials is ongoing with the aim to evaluate several other alterations and pathways as new potential targets in metastatic UC. In this review, we will discuss the recent advances and highlight future directions of the medical treatment of UC, with a particular focus on recently published data and ongoing active and recruiting trials.

Prognosis significance of indoleamine 2, 3-dioxygenase, programmed death ligand-1 and tumor-infiltrating immune cells in microenvironment of breast cancer

INTRODUCTION

The immune microenvironment plays an increasingly important role in predicting the prognosis of multiple tumors and selecting patients for immunotherapy trials. We studied the expression of indoleamine 2, 3-dioxygenase (IDO) and programmed death ligand-1 (PD-L1), detected the proportion of tumor-infiltrating immune cells (TIIs), and further analyzed the association of these immunological characteristics with the clinicopathological parameters and prognosis of breast cancer patients.

METHODS

Immunohistochemical staining for IDO, PD-L1, CD4, CD8, Foxp3, CD20, CD56 and CD68 expression in breast cancer tissues was carried out. IDO and PD-L1 expression were scored by extent in tumor cells. TIIs expressing CD4, CD8, Foxp3, CD20, CD56 or CD68 were evaluated by positive count. Clinicopathological characteristics and follow-up were recorded.

RESULTS

The frequencies of IDO-high-expressing and PD-L1-expressing tissue were 33.77% and 24.68%, respectively. The co-expression of IDO and PD-L1 was identified in 16/77 (20.78%) of cases. IDO high expression, CD4⁺ T cells and CD56⁺ cells were most frequently observed in patients with tumor-draining lymph nodes(TDLNs) metastasis. Immune cells were more common in non-luminal breast cancer than in luminal breast cancer. In survival analysis, PFS were not associated with high levels of IDO and PD-L1, nor were TIIs. However, CD20 and CD68 were significant risk factors for prognostic after adjusting covariates by COX regression. IDO^highFoxp3^highT patients had a tendency with shorter progression-free survival.

CONCLUSIONS

Although we found a limited prognostic effect of TIIs on survival in breast cancer patients, IDO combined with TIIs can help to evaluate the prognosis of patients.

Chemoresistance was correlated with elevated expression and activity of indoleamine 2,3-dioxygenase in breast cancer

BACKGROUND

Indoleamine 2,3-dioxygenase (IDO) catalyses degradation of the essential amino acid tryptophan leading to the production of immunosuppressive kynurenine and tryptophan exhausting. IDO expression and activity contribute to aggressive tumor growth, inferior therapeutic gain and poor prognosis. The aim of this study was to explore the association between chemoresistance and IDO expression, activity in breast cancer METHODS: Immunohistochemistry was applied for evaluating IDO expression in biopsy tissues. Serum IDO activity was examined via High-performance liquid chromatography (HPLC). Western blots (WB), HPLC and Real-time PCR (RT-PCR) were used to analyze IDO protein, IDO enzyme activity and IDO gene expression in original and paclitaxel-resistant cells respectively. Logistic regression and survival analysis were applied to explore the association between chemoresistance and IDO expression, activity in breast cancer.

RESULTS

IDO expression in tumor tissues was associated with serum IDO activity (P = 0.004). Both IDO expression in tumor and serum activity were associated with clinical tumor stage, node stage and estrogen receptor (ER) status (all P < 0.05); clinical response and pathologic complete response (pCR) to NAC were both related to IDO expression and activity prior NAC (all P < 0.05). Multivariate analysis showed IDO activity before NAC was the only independent factor affected pCR (P = 0.032). ROC curves showed that the IDO expression and activity had discriminative ability for predicting the clinical response and pCR. In the prognostic analysis, patients with high IDO expression had significantly impaired overall survival (5 year survival rate: 53.57% vs 80.00%) and progression-free survival (5 year survival rate: 46.43% vs 72.00%, P = 0.031 and P = 0.046). In vitro, significantly increased IDO protein, IDO mRNA expression and IDO enzyme activity in paclitaxel-resistant cells were demonstrated in comparing of sensitive cells.

CONCLUSION

IDO expression and activity associated with advanced breast cancer, poor response to neoadjuvant chemotherapy and prognosis. IDO expression and activity were significantly increased in paclitaxel-resistant breast cancer cells.

JAK-STAT Signaling: A Double-Edged Sword of Immune Regulation and Cancer Progression

Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling mediates almost all immune regulatory processes, including those that are involved in tumor cell recognition and tumor-driven immune escape. Antitumor immune responses are largely driven by STAT1 and STAT2 induction of type I and II interferons (IFNs) and the downstream programs IFNs potentiate. Conversely, STAT3 has been widely linked to cancer cell survival, immunosuppression, and sustained inflammation in the tumor microenvironment. The discovery of JAK-STAT cross-regulatory mechanisms, post-translational control, and non-canonical signal transduction has added a new level of complexity to JAK-STAT governance over tumor initiation and progression. Endeavors to better understand the vast effects of JAK-STAT signaling on antitumor immunity have unearthed a wide range of targets, including oncogenes, miRNAs, and other co-regulatory factors, which direct specific phenotypical outcomes subsequent to JAK-STAT stimulation. Yet, the rapidly expanding field of therapeutic developments aimed to resolve JAK-STAT aberrations commonly reported in a multitude of cancers has been marred by off-target effects. Here, we discuss JAK-STAT biology in the context of immunity and cancer, the consequences of pathway perturbations and current therapeutic interventions, to provide insight and consideration for future targeting innovations.

The Complex Interaction between the Tumor Micro-Environment and Immune Checkpoints in Breast Cancer

The progression of breast cancer and its association with clinical outcome and treatment remain largely unexplored. Accumulating data has highlighted the interaction between cells of the immune system and the tumor microenvironment in cancer progression, and although studies have identified multiple facets of cancer progression within the development of the tumor microenvironment (TME) and its constituents, there is lack of research into the associations between breast cancer subtype and staging. Current literature has provided insight into the cells and pathways associated with breast cancer progression through expression analysis. However, there is lack of co-expression studies between immune pathways and cells of the TME that form pro-tumorigenic relationships contributing to immune-evasion. We focus on the immune checkpoint and TME elements that influence cancer progression, particularly studies in molecular subtypes of breast cancer.

Enhanced cancer therapy through synergetic photodynamic/immune checkpoint blockade mediated by a liposomal conjugate comprised of porphyrin and IDO inhibitor

Cancer metastases is still a hurdle for good prognosis and live quality of breast cancer patients. Treatment strategies that can inhibit metastatic cancer while treating primary cancer are needed to improve the therapeutic effect of breast cancer. Methods: In this study, a dual functional drug conjugate comprised of protoporphyrin IX and NLG919, a potent indoleamine-2,3-dioxygenase (IDO) inhibitor, is designed to combine photodynamic therapy and immune checkpoint blockade to achieve both primary tumor and distant metastases inhibition. Liposomal delivery is applied to improve the biocompatibility and tumor accumulation of the drug conjugate (PpIX-NLG@Lipo). A series of in vitro and in vivo experiments were carried out to examine the PDT effect and IDO inhibition activity of PpIX-NLG@Lipo, and subsequently evaluate its anti-tumor capability in the bilateral 4T1 tumor-bearing mice. Results: The in vitro and in vivo experiments demonstrated that PpIX-NLG@Lipo possess strong ability of ROS generation to damage cancer cells directly through PDT. Meanwhile, PpIX-NLG@ Lipo can induce immunogenic cell death to elicit the host immune system. Furthermore, PpIX-NLG@Lipo interferes the activity of IDO, which can amplify PDT-induced immune responses, leading to an increasing amount of CD8+ T lymphocytes infiltrated into tumor site, finally achieve both primary and distant tumor inhibition. Conclusion: This work presents a novel conjugate approach to synergize photodynamic therapy and IDO blockade for enhanced cancer therapy through simultaneously inhibiting both primary and distant metastatic tumor.

PTEN-deficient prostate cancer is associated with an immunosuppressive tumor microenvironment mediated by increased expression of IDO1 and infiltrating FoxP3+ T regulatory cells

BACKGROUND

Accumulating evidence shows that tumor cell-specific genomic changes can influence the cross talk between cancer cells and the surrounding tumor microenvironment (TME). Loss of the PTEN tumor suppressor gene is observed in 20% to 30% of prostate cancers (PCa) when first detected and the rate increases with PCa progression and advanced disease. Recent findings implicate a role for PTEN in cellular type I interferon response and immunosuppression in PCa. However, the way that PTEN inactivation alters antitumor immune response in PCa is poorly understood.

MATERIALS AND METHODS

To investigate the changes associated with PTEN loss and an immunosuppressive TME in PCa, we used CIBERSORT to estimate the relative abundance of 22 immune-cell types from 741 primary and 96 metastatic tumors. Our in silico findings were then validated by immunohistochemical analysis of immune cells and IDO1 and PDL1 checkpoint proteins in a cohort of 94 radical prostatectomy specimens.

RESULTS

FoxP3+ T regulatory cells (Tregs) were significantly increased in PTEN-deficient PCa in all three public domain cohorts. Loss of PTEN in bone metastases was associated with lower CD8+ T-cell abundance, but in liver metastasis, FoxP3+ Tregs were present at higher levels. PTEN-deficient lymph node metastasis had a distinct profile, with high levels of CD8+ T cells. Moreover, we found that metastatic PCa presents higher abundance of FoxP3+ Treg when compared to primary lesions. Since PTEN-deficient tumors are likely to be immunosuppressed as a consequence of increased FoxP3+ Tregs, we then evaluated the localization and expression of IDO1, PDL1 immune checkpoints, and the corresponding density of FoxP3+ Treg and CD8+ T cells using our validation cohort (n = 94). We found that IDO1 protein expression and FoxP3+ Treg density were higher in neoplastic glands compared with benign adjacent tissue. Moreover, higher densities of FoxP3+ Treg cells in both stromal (P = 0.04) and tumor (P = 0.006) compartments were observed in PTEN-deficient tumors compared to tumors that retained PTEN activity. Similarly, IDO1 protein expression was significantly increased in the tumor glands of PTEN-deficient PCa (P < 0.0001). Spearman correlation analysis showed that IDO1 expression was significantly associated with FoxP3+ Treg and CD8+ T-cell density (P < 0.01).

CONCLUSIONS

Our findings imply that PTEN deficiency is linked to an immunosuppressive state in PCa with distinct changes in the frequency of immune cell types in tumors from different metastatic sites. Our data suggest that determining PTEN status may also help guide the selection of patients for future immunotherapy trials in localized and metastatic PCa.

Phase I Study of the Indoleamine 2,3-Dioxygenase 1 (IDO1) Inhibitor Navoximod (GDC-0919) Administered with PD-L1 Inhibitor (Atezolizumab) in Advanced Solid Tumors

PURPOSE

IDO1 induces immune suppression in T cells through l-tryptophan (Trp) depletion and kynurenine (Kyn) accumulation in the local tumor microenvironment, suppressing effector T cells and hyperactivating regulatory T cells (Treg). Navoximod is an investigational small-molecule inhibitor of IDO1. This phase I study evaluated safety, tolerability, pharmacokinetics, and pharmacodynamics of navoximod in combination with atezolizumab, a PD-L1 inhibitor, in patients with advanced cancer.

PATIENTS AND METHODS

The study consisted of a 3+3 dose-escalation stage (n = 66) and a tumor-specific expansion stage (n = 92). Navoximod was given orally every 12 hours continuously for 21 consecutive days of each cycle with the exception of cycle 1, where navoximod administration started on day -1 to characterize pharmacokinetics. Atezolizumab was administered by intravenous infusion 1,200 mg every 3 weeks on day 1 of each cycle.

RESULTS

Patients (n = 157) received navoximod at 6 dose levels (50-1,000 mg) in combination with atezolizumab. The maximum administered dose was 1,000 mg twice daily; the MTD was not reached. Navoximod demonstrated a linear pharmacokinetic profile, and plasma Kyn generally decreased with increasing doses of navoximod. The most common treatment-related AEs were fatigue (22%), rash (22%), and chromaturia (20%). Activity was observed at all dose levels in various tumor types (melanoma, pancreatic, prostate, ovarian, head and neck squamous cell carcinoma, cervical, neural sheath, non-small cell lung cancer, triple-negative breast cancer, renal cell carcinoma, urothelial bladder cancer): 6 (9%) dose-escalation patients achieved partial response, and 10 (11%) expansion patients achieved partial response or complete response.

CONCLUSIONS

The combination of navoximod and atezolizumab demonstrated acceptable safety, tolerability, and pharmacokinetics for patients with advanced cancer. Although activity was observed, there was no clear evidence of benefit from adding navoximod to atezolizumab.

Beyond PD-1/PD-L1 Inhibition: What the Future Holds for Breast Cancer Immunotherapy

Cancer immunotherapy has altered the management of human malignancies, improving outcomes in an expanding list of diseases. Breast cancer - presumably due to its perceived low immunogenicity - is a late addition to this list. Furthermore, most of the focus has been on the triple negative subtype because of its higher tumor mutational load and lymphocyte-enriched stroma, although emerging data show promise on the other breast cancer subtypes as well. To this point the clinical use of immunotherapy is limited to the inhibition of two immune checkpoints, Programmed Cell Death Protein 1 (PD-1) and Cytotoxic T-lymphocyte-associated Protein 4 (CTLA-4). Consistent with the complexity of the regulation of the tumor - host interactions and their lack of reliance on a single regulatory pathway, combinatory approaches have shown improved efficacy albeit at the cost of increased toxicity. Beyond those two checkpoints though, a large number of co-stimulatory or co-inhibitory molecules play major roles on tumor evasion from immunosurveillance. These molecules likely represent future targets of immunotherapy provided that the promise shown in early data is translated into improved patient survival in randomized trials. The biological role, prognostic and predictive implications regarding breast cancer and early clinical efforts on exploiting these immune-related therapeutic targets are herein reviewed.

Immunotherapy in breast cancer: Current status and future directions

Breast cancer, one of the leading causes of death in women in the United States, challenges therapeutic success in patients due to tumor heterogeneity, treatment resistance, metastasis and disease recurrence. Knowledge of immune system involvement in normal breast development and breast cancer has led to extensive research into the immune landscape of breast cancer and multiple immunotherapy clinical trials in breast cancer patients. However, poor immunogenicity and T-cell infiltration along with heightened immunosuppression in the tumor microenvironment have been identified as potential challenges to the success of immunotherapy in breast cancer. Oncodrivers, owing to their enhanced expression and stimulation of tumor cell proliferation and survival, present an excellent choice for targeted immunotherapy development in breast cancer. Loss of anti-tumor immune response specific to oncodrivers has been reported in breast cancer patients as well. Dendritic cell vaccines have been tested for their efficacy in generating anti-tumor T-cell response against specific tumor-associated antigens and oncodrivers and have shown improved survival outcome in patients. Here, we review the current status of immunotherapy in breast cancer, focusing on dendritic cell vaccines and their therapeutic application in breast cancer. We further discuss future directions of breast cancer immunotherapy and potential combination strategies involving dendritic cell vaccines and existing chemotherapeutics for improved efficacy and better survival outcome in breast cancer.

Frequent discordance in PD-1 and PD-L1 expression between primary breast tumors and their matched distant metastases

Programmed death-1 (PD-1) is an immune checkpoint that is able to inhibit the immune system by binding to its ligand programmed death-ligand 1 (PD-L1). In many cancer types, among which breast cancer, prognostic and/or predictive values have been suggested for both PD-1 and PD-L1. Previous research has demonstrated discrepancies in PD-L1 expression between primary breast tumors and distant metastases, however data so far have been scarce. We therefore evaluated immunohistochemical expression levels of PD-1 and PD-L1 in primary breast tumors and their paired distant metastases, and evaluated prognostic values. Tissue microarrays from formalin-fixed paraffin-embedded resection specimens of primary breast cancers and their matched distant metastases were immunohistochemically stained for PD-1 and PD-L1. PD-1 was available in both primary tumor and metastasis in 82 patients, and PD-L1 in 49 patients. PD-1 was discrepant between primary tumor and metastasis in half of the patients (50%), PD-L1 on tumor cells was discrepant in 28.5%, and PD-L1 on immune cells in 40.8% of the patients. In primary tumors there was a correlation between PD-1 positivity and a higher tumor grade, and between immune PD-L1 and ER negativity. In survival analyses, a significantly better overall survival was observed for patients with PD-L1 negative primary breast tumors that developed PD-L1 positive distant metastases (HR 3.013, CI 1.201-7.561, p = 0.019). To conclude, PD-1 and tumor and immune PD-L1 seem to be discordantly expressed between primary tumors and their matched distant metastases in about one-third to a half of the breast cancer patients. Further, gained expression of PD-L1 in metastases seems to indicate better survival. This illustrates the need of reassessing PD-1 and PD-L1 expression on biopsies of distant metastases to optimize the usefulness of these biomarkers.

Indoleamine 2,3-dioxygenase expression and overall survival in patients diagnosed with breast cancer in Pakistan

Background

Immune dysfunction in breast cancer patients is well established. Indoleamine 2,3-dioxygenase (IDO) is an immunosuppressive enzyme that is linked with progression of cancer. IDO is overexpressed in triple-negative breast cancer (TNBC) cases.

Materials and methods

We conducted the first study to analyze IDO expression and overall survival in breast cancer cases in Pakistan. Expression of IDO, estrogen receptor (ER), progesterone receptor (PR), and human EGF receptor 2 (HER2) was evaluated by immunohistochemistry. Formalin-fixed paraffin-embedded breast cancer tissues of 100 (TNBC, n=49 and non-TNBC, n=51) patients were obtained from Shaukat Khanum Memorial Cancer Hospital and Research Centre. IDO expression was analyzed in association with clinicopathological features and overall survival. A total of 100 patients were classified based on the ordinal IDO score variables as low, medium, and high. In addition, overall mean age and SD of patients was 48.28±11.82.

Results

Immunohistochemical analysis showed that high IDO was observed in the TNBC patients (65.3%) compared to that in the non-TNBC patients (33.3%). Multivariable analyses showed that TNBC was an independent risk factor for high IDO expression. Overall survival was also significantly associated with IDO score.

Conclusion

Our study showed that IDO protein expression is higher in TNBC patients (P<0.01) and may suggest its role in disease pathogenesis. TNBC might be effectively treated with IDO inhibitors. Furthermore, high IDO expression is considerably associated with overall decreased patient survival. IDO might be utilized as a potential biomarker and immunotherapeutic target in breast cancer patients.

PD-L1 and IDO expression in cervical and vulvar invasive and intraepithelial squamous neoplasias: implications for combination immunotherapy

AIMS

The immunoregulatory enzyme indoleamine dioxygenase 2,3 (IDO) has been implicated in cervical and vulvar squamous carcinomas (SCC) and may represent a mechanism of resistance to anti-PD-1/anti-PD-L1 therapy. However, the relationship between IDO and PD-L1 has not been well-investigated.

METHODS AND RESULTS

Sixty-five cases of cervical and vulvar intraepithelial neoplasia and SCC were assessed for IDO and PD-L1 expression. Overall, tumoral PD-L1 expression was seen in 72% of SCC, while 50% expressed IDO; co-expression was seen in 42%. Using the combined positive score (CPS) threshold of 1 to account for both tumoral and immune staining, 83% of SCC expressed PD-L1, 61% expressed IDO and 53% showed co-expression. Cervical SCCs were significantly more likely than human papillomavirus (HPV)-related vulvar SCCs to express tumoral IDO (75% versus 13%, P < 0.001) and demonstrate an IDO CPS ≥ 1 (88% versus 25%, P < 0.001); no significant differences were seen for PD-L1. Additionally, there were no significant differences in IDO and PD-L1 expression in dVIN-associated versus HPV-associated vulvar SCC. In contrast to SCC, the majority of intraepithelial lesions were entirely negative for tumoral PD-L1 and IDO and had a CPS score of <1.

CONCLUSIONS

In summary, IDO and PD-L1 co-expression is common in cervical SCCs and, to a lesser extent, vulvar SCCs. These data suggest a role for combination immunotherapy in a subset of cervical SCCs as well as select vulvar SCCs. Expression for both markers is less common in intraepithelial lesions, providing no strong support for this form of immunotherapy in the absence of invasion.

Indoleamine 2, 3-dioxygenase inhibitors in immunochemotherapy of breast cancer: challenges and opportunities

Trafficking of macromolecular immunotherapy agent into the tumor microenvironment (TME) is a challenging issue. In the TME, cancer cells exploit indoleamine 2, 3-dioxygenase (IDO), as a cytosolic enzyme that catalyzes the L-tryptophan (Trp) through the kynurenine (Kyn) pathway, which could negatively regulate the activity of T cells. Thus, Trp/Kyn pathway, can be targeted with novel treatment modalities such as IDO1 inhibitor to benefit patients with aggressive solid tumors.

Cancer Cell-Intrinsic PD-1 and Implications in Combinatorial Immunotherapy

Programmed death 1 (PD-1) and its two natural ligands PD-L1 and PD-L2 are responsible for delivering inhibitory signals that regulate the balance between T cell activation, tolerance, and immunopathology. In previous studies, PD-1 was found only expressed on the surface of immune cells, such as T cells and B cells while PD-1’s ligands PD-L1 and PD-L2 were found expressed in some tumor cells. However, recent studies revealed intrinsic expression of PD-1 in melanoma and some other cancers. In melanoma cells, PD-1 can be activated by its ligand PD-L1 expressed by tumor cells, modulating downstream mammalian target of rapamycin signaling and promoting tumor growth independent of adaptive immunity. In addition to melanoma, PD-1 was also detected in liver cancer cells as well as in non-small lung cancer cells. Unlike its oncogenic functions in melanoma and hepatic carcinoma cells, PD-1 seemed to play a distinct role in lung cancer, as blockade of PD-1 instead promoted tumor cells proliferation. Tumor-intrinsic PD-1 expression seems to be widespread in many tumor types, according to our reanalysis on cancer transcriptomic and proteomic data. The multifaceted roles of PD-1 in tumor cells beyond immune checkpoint signaling may explain the differential therapeutic effects of anti-PD-1 and anti-PD-L1 drugs and provide crucial information when developing combinatorial approaches to enhance antitumor immunity.