Since the discovery of indoleamine 2,3-dioxygenase 1 (IDO1) as an attractive target for anticancer therapy in 2003, the search for inhibitors has been intensely pursued both in academia and in pharmaceutical companies. Many novel IDO1 inhibitor scaffolds have been described, and a few potent compounds have entered clinical trials. However, a significant number of the reported compounds contain problematic functional groups, suggesting that enzyme inhibition could be the result of undesirable side reactions instead of selective binding to IDO1. Here, we describe issues in the employed experimental protocols, review and classify reported IDO1 inhibitors, and suggest different approaches for confirming viable inhibitor scaffolds.

https://pubsdc3.acs.org/doi/pdfplus/10.1021/acs.jmedchem.5b00326

Challenges in the Discovery of Indoleamine 2,3-Dioxygenase 1 (IDO1) Inhibitors

Disclosed are compounds of Formula (I), methods of using the compounds as immunomodulators, and pharmaceutical compositions comprising such compounds The compounds are useful in treating, preventing or ameliorating diseases or disorders such as cancer or infections

Heterocyclic compounds as immunomodulators

Tryptophan metabolism has been recognized as an important mechanism in immune tolerance. Indoleamine 2,3-dioxygenase plays a key role in local tryptophan metabolism via the kynurenine pathway and has emerged as a therapeutic target for cancer immunotherapy. Our prior study identified phenyl benzenesulfonyl hydrazide 2 as a potent in vitro (though not in vivo) inhibitor of indoleamine 2,3-dioxygenase. Further lead optimization to improve in vitro potencies and pharmacokinetic profiles resulted in N′-(4-bromophenyl)-2-oxo-2,3-dihydro-1H-indole-5-sulfonyl hydrazide 40, which demonstrated 59% oral bioavailability and 73% of tumor growth delay without apparent body weight loss in the murine CT26 syngeneic model, after oral administration of 400 mg/kg. Accordingly, 40, is proposed as a potential drug lead worthy of advanced preclinical evaluation.

Phenyl Benzenesulfonylhydrazides Exhibit Selective Indoleamine 2,3-Dioxygenase Inhibition with Potent in Vivo Pharmacodynamic Activity and Antitumor Efficacy.

Depression is highly prevalent worldwide and a leading cause of disabilty. However, the medications currently available to treat depression fail to adequately relieve depressive symptoms for a large number of patients. Research into the aberrant overactivation of the kynurenine pathway and the production of various active metabolites has brought new insight into the progression of depression. IDO and TDO are the first and rate-limiting enzymes in the kynurenine pathway and regulate the production of active metabolites. There is substantial evidence that TDO and IDO enzyme are activated during depression, and therefore, IDO and TDO inhibitors have been identified as ideal therapeutic targets for depressive disorder. Hence, this review will focus on the kynurenine branch of tryptophan metabolism and describe the role of IDO and TDO in the pathology of depression. In addition, this review will compare the relative imbalance between KYNA and neurotoxic kynurenine metabolites in different psychiatric disorders. Finally, this review is also directed toward assessing whether IDO and TDO are potential therapeutic target in depression associated with other diseases such as diabetes and/or cancer, as well as the development of potent IDO and TDO inhibitors.

IDO and TDO as a potential therapeutic target in different types of depression.

Objective: Treatment with recombinant interferon is associated with high rates of psychiatric comorbidity. We investigated the relation between catabolism of the essential amino acid tryptophan, being rate-limiting of peripheral and cerebral serotonin formation, and psychiatric symptoms in patients undergoing combination treatment with interferon-a and ribavirin. Patients and Methods: Eighteen patients with viral hepatitis C who received interferon were included. A psychiatrist screened patients before and while on interferon-a treatment for 2 months, using a structured diagnostic interview. Fasting plasma tryptophan and platelet serotonin levels were measured at each visit. Results: At baseline no evident psychopathology was observed. After 2 months of interferon treatment, 10 patients experienced increased irritability. No other structural psychopathology was observed. Decreased plasma tryptophan level correlated with the presence of irritability (p = .047). Platelet serotonin levels were found to be decreased during treatment (p = .002). Conclusions: Aggressive impulse dysregulation is highly prevalent in patients receiving interferon treatment. This is associated with decreased plasma tryptophan levels which may lead to attenuated peripheral and central serotonergic neurotransmission. Key words: interferon, tryptophan, inflammation, serotonin, irritability.

Irritability rather than depression during interferon treatment is linked to increased tryptophan catabolism.

The present application provides novel inhibitors of indoleamine 2,3-dioxygenase-1 and/or indoleamine 2,3-dioxygenase-2 and/or tryptophan 2,3-dioxygenase, metabolites thereof, and phannaceutically acceptable salts or prodrugs thereof. Also provided are methods for preparing these compounds. A therapeutically effective amount of one or more of the compounds of formula (I) is useful in treating diseases resulting from dysregulation of the kynurenine pathway. Compounds of formula (I) act by inhibiting the enzymatic activity or expression of indoleamine 2,3-dioxygenase-1 and/or indoleamine 2,3-dioxygenase-2 and/or tryptophan 2,3-dioxygenase.

Inhibitors of the kynurenine pathway

The present application provides novel kynurenine pathway inhibitors and pharmaceutically acceptable salts and prodrugs thereof. Also provided are methods for preparing these compounds. These compounds are useful in regulating the kynurenine pathway and the activity of indoleamine 2,3-dioxygenase and/or tryptophan 2,3-dioxygenase by administering a therapeutically effective amount of one more of the compounds of formula (I) to a patient. By doing so, these compounds are effective in treating conditions associated with the dysregulation of the kynurenine pathway. A variety of conditions can be treated using these compounds and include diseases which are characterized by immunosuppression, abnormal cellular proliferation and/or inflammation. In one embodiment, the disease is cancer. In another embodiment, the disease is a viral infection. In a further embodiment, the disease is depression.

Aminonitriles as kynurenine pathway inhibitors

The invention relates to a compound of formula (I) wherein X 1 to X 4 and R C to R G are defined as in the description and in the claims The compound of formula (I) can be used as a medicament

Novel iminonitrile derivatives

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Inhibitors of the kynurenine pathway

Aminonitriles as kynurenine pathway inhibitors

Novel iminonitrile derivatives