Indoleamine 2, 3-dioxygenase 1 (IDO1), IDO2, and tryptophan 2, 3-dioxygenase (TDO) comprise a family of enzymes that catalyze the first- and rate-limiting step associated with the catabolic ...conversion of tryptophan (Trp) into kynurenine (Kyn). Through subsequent enzymatic and spontaneous reactions, Kyn is further converted into the energetic substrates, NAD(+) and ATP, to fuel cellular metabolic functions. Coincidently, the depletion of Trp and accumulation of Kyn has been demonstrated to induce effector T-cell apoptosis/dysfunction and immunosuppressive regulatory T-cell induction, respectively. Similar to other immune checkpoints, IDO1 and TDO are suggested to be important targets for immunotherapeutic intervention. This is represented by the recent growth of efforts to inhibit the Trp-to-Kyn pathway as a means to control immunosuppression. Inhibitors currently in clinical trials, INCB024360, GDC-0919, indoximod, and an IDO1 peptide-based vaccine, are being evaluated for their efficacy against a wide range of cancers including melanoma, glioblastoma, non-small cell lung, pancreatic, and/or breast cancer, as well as metastatic disease. Despite the rapid development of potent clinical grade inhibitors, strategic questions remain. Here, we review the state of the literature with respect to current therapeutic inhibitors of tryptophan catabolism, evaluation of those efforts preclinically and clinically, compensatory changes that occur with therapeutic targeting, as well as newly recognized signaling features that raise critical questions to the field. Given the rapidly evolving interest in determining how IDO1/TDO, and to an unknown extent, IDO2, can be targeted for increasing cancer immunotherapeutic efficacy, we present a brief but comprehensive analysis that addresses critical questions, while highlighting the mechanics that remain to be explored.
Fare Well, Illyria Binder, David
2013, 20131110, 2013-11-01, 2013-01-11
eBook
As a reporter for the prestigious New York Times the author interviewed many of the leading political figures of the Balkans (Illyria). He also sought out the area's intellectuals, many of them ...critical of their leaders, and everyday people who provide a sense of daily life. He devotes a chapter to each ethnic group from Vlachs to Serbs, talks about their differences and similarities, and does so without giving offense. He also provides a short historical account of the various places he visits, which deepens our understanding of the local cultures.
Cancers often relapse after adoptive therapy, even though specific T cells kill cells from the same cancer efficiently in vitro. We found that tumor eradication by T cells required high affinities of ...the targeted peptides for major histocompatibility complex (MHC) class I. Affinities of at least 10 nM were required for relapse-free regression. Only high-affinity peptide-MHC interactions led to efficient cross-presentation of antigen, thereby stimulating cognate T cells to secrete cytokines. These findings highlight the importance of targeting peptides with high affinity for MHC class I when designing T cell-based immunotherapy.
► Tumor relapse versus eradication is determined by affinity of peptide for MHC. ► Outcome of adoptive T cell therapy is determined by affinity of peptide for MHC. ► Stroma is only destroyed in tumors expressing peptides with high affinity for MHC. ► Efficient cross-presentation is dependent on high peptide-MHC affinity
Glioblastoma is the most aggressive primary brain tumor in adults with a median survival of 15-20 months. Numerous approaches and novel therapeutics for treating glioblastoma have been investigated ...in the setting of phase III clinical trials, including a recent analysis of the immune checkpoint inhibitor, nivolumab (anti-PD-1), which failed to improve recurrent glioblastoma patient survival. However, rather than abandoning immune checkpoint inhibitor treatment for glioblastoma, which has shown promise in other types of cancer, ongoing studies are currently evaluating this therapeutic class when combined with other agents.
Here, we investigated immunocompetent orthotopic mouse models of glioblastoma treated with the potent CNS-penetrating IDO1 enzyme inhibitor, BGB-5777, combined with anti-PD1 mAb, as well as radiotherapy, based on our recent observation that tumor-infiltrating T cells directly increase immunosuppressive IDO1 levels in human glioblastoma, the previously described reinvigoration of immune cell functions after PD-1 blockade, as well as the proinflammatory effects of radiation.
Our results demonstrate a durable survival benefit from this novel three-agent treatment, but not for any single- or dual-agent combination. Unexpectedly, treatment efficacy required IDO1 enzyme inhibition in non-glioblastoma cells, rather than tumor cells. Timing of effector T-cell infiltration, animal subject age, and usage of systemic chemotherapy, all directly impacted therapy-mediated survival benefit.
These data highlight a novel and clinically relevant immunotherapeutic approach with associated mechanistic considerations that have formed the basis of a newly initiated phase I/II trial for glioblastoma patients.
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Indoleamine 2,3 dioxygenase 1 (IDO1) mediates potent immunosuppression in multiple preclinical models of cancer. However, the basis for elevated IDO1 expression in human cancer, including the most ...common primary malignant brain tumor in adults, glioblastoma (GBM), is poorly understood. The major objective of this study is to address this gap in our understanding of how IDO1 expression contributes to the biology of GBM, and whether its level of expression is a determinant of GBM patient outcome.
Patient-resected GBM, The Cancer Genome Atlas, human T-cell:GBM cocultures, as well as nu/nu, NOD-
and humanized (NSG-SGM3-BLT) mice-engrafted human GBM form the basis of our investigation.
hybridization for
revealed transcript expression throughout patient-resected GBM, whereas immunohistochemical IDO1 positivity was highly variable. Multivariate statistical analysis revealed that higher levels of IDO1 transcript predict a poor patient prognosis (
= 0.0076). GBM
mRNA levels positively correlated with increased gene expression for markers of cytolytic and regulatory T cells, in addition to decreased patient survival. Humanized mice intracranially engrafted human GBM revealed an IFNγ-associated T-cell-mediated increase of intratumoral
Our data demonstrate that high intratumoral
mRNA levels correlate with a poor GBM patient prognosis. It also confirms the positive correlation between increased GBM
levels and human-infiltrating T cells. Collectively, this study suggests that future efforts aimed at increasing T-cell-mediated effects against GBM should consider combinatorial approaches that coinhibit potential T-cell-mediated IDO1 enhancement during therapy.
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Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults and still remains incurable. Although immunotherapeutic vaccination against GBM has demonstrated immune-stimulating ...activity with some promising survival benefits, tumor relapse is common, highlighting the need for additional and/or combinatorial approaches. Recently, antibodies targeting immune checkpoints were demonstrated to generate impressive clinical responses against advanced melanoma and other malignancies, in addition to showing potential for enhancing vaccination and radiotherapy (RT). Here, we summarize the current knowledge of central nervous system (CNS) immunosuppression, evaluate past and current immunotherapeutic trials and discuss promising future immunotherapeutic directions to treat CNS-localized malignancies.
Highlights • Non-tumor cell IDO1 predominantly contributes to Kyn accumulation in mouse GBM. • Immune checkpoint blockade requires IDO1 for maximal survival against mouse GBM. • Checkpoint-mediated ...survival is associated with higher Kyn levels in WT compared to IDO1KO mice. • Characterization of new glioma cell lines from wildtype and IDO1-deficient mice.
Physicians and other healthcare professionals are often the end users of medical innovation; however, they are rarely involved in the beginning design stages. This often results in ineffective ...healthcare solutions with poor adoption rates. At the early design stage, innovation would benefit from input from healthcare professionals. This report describes the first-ever rehabilitation hackathon—an interdisciplinary and competitive team event aimed at accelerating and improving healthcare solutions and providing an educational experience for participants. Hackathons are gaining traction as a way to accelerate innovation by bringing together a diverse group of interdisciplinary professionals from different industries who work collaboratively in teams and learn from each other, focus on a specific problem (“pain point”), develop a solution using design thinking techniques, pitch the solution to participants, gather fast feedback and quickly alter the prototype design (“pivoting”). 102 hackers including 19 (18.6 %) physicians and other professionals participated, and over the course of 2 days worked in teams, pitched ideas and developed design prototypes. Three awards were given for prototypes that may improve function in persons with disabilities. 43 hackers were women (42.2 %) and 59 men (57.8 %); they ranged in age from 16 to 79 years old; and, of the 75 hackers who reported their age, 63 (84 %) were less than 40 years old and 12 (16 %) were 40 years or older. This report contributes to the emerging literature on healthcare hackathons as a means of providing interdisciplinary education and training and supporting innovation.
Salmonella Typhimurium, engineered to express flagellin B, recently demonstrated unprecedented tumor control through a TLR-dependent mechanism. Here, we review new observations that support the ...potential of utilizing modified bacteria to enhance antitumor immunity. We also discuss the implications of these findings for clinical applications, including immune checkpoint blockade therapies.
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