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Goodpasture's disease manifests as rapidly progressive glomerulonephritis. Current immunosuppressive treatments do not specifically target the pathological immune response and have significant side effects. Like most autoimmune diseases, the strongest genetic association is with the HLA alleles. Inheritance of HLA-DR15 confers susceptibility, and structure-function studies have shown that HLA-DR15 plays a causative role in activating autoreactive pro-inflammatory T cells. Thus, specific inhibition of HLA-DR15 would provide a targeted therapeutic approach. We hypothesised that PV-267, an HLA-DR15-specific inhibitor, would effectively block HLA-DR15 presentation of the dominant epitope, attenuate the activation of autoreactive T cells, and limit disease. Using humanised HLA-DR15 transgenic mice, α3135-145-specific, pro-inflammatory T cell recall responses were measured using IFN-γ and IL-17A ELISPOTs and by proliferation assay. To determine if PV-267 could limit disease, experimental autoimmune anti-GBM glomerulonephritis was induced in HLA-DR15 transgenic mice (on an Fcgr2b-/- background), and functional and histological disease endpoints were measured. PV-267 effectively inhibited α3135-145-specific immune responses and disease development. Mice treated prior to immunization with α3135-145 had reduced α3135-145-specific recall responses, and limited disease by albuminuria, histological glomerular injury, IgG deposition, and inflammatory cell infiltrates. PV-267 treatment commencing after the onset of active anti-α3(IV)NC1 autoimmunity attenuated functional and histological renal injury. When treatment was administered after disease was established, PV-267 limited the severity of histological injury. In conclusion, HLA-DR15 inhibition attenuates α3(IV)NC1-specific pro-inflammatory responses and could be used as an adjunct therapy for anti-GBM disease.

We previously identified TRAIL-inducing compound 10 (TIC10), also known as NSC350625 or ONC201, from a NCI chemical library screen as a small molecule that has potent anti-tumor efficacy and a benign safety profile in preclinical cancer models. The chemical structure that was originally published by Stahle, et. al. in the patent literature was described as an imidazo[1,2-a]pyrido[4,3-d]pyrimidine derivative. The NCI and others generally accepted this as the correct structure, which was consistent with the mass spectrometry analysis outlined in the publication by Allen et. al. that first reported the molecule's anticancer properties. A recent publication demonstrated that the chemical structure of ONC201 material from the NCI is an angular [3,4-e] isomer of the originally disclosed, linear [4,3-d] structure. Here we confirm by NMR and X-ray structural analysis of the dihydrochloride salt form that the ONC201 material produced by Oncoceutics is the angular [3,4-e] structure and not the linear structure originally depicted in the patent literature and by the NCI. Similarly, in accordance with our biological evaluation, the previously disclosed anti-cancer activity is associated with the angular structure and not the linear isomer. Together these studies confirm that ONC201, produced by Oncoceutics or obtained from the NCI, possesses an angular [3,4-e] structure that represents the highly active anti-cancer compound utilized in prior preclinical studies and now entering clinical trials in advanced cancers.

Anti-cancer small molecule ONC201 upregulates the integrated stress response (ISR) and acts as a dual inactivator of Akt/ERK, leading to TRAIL gene activation. ONC201 is under investigation in multiple clinical trials to treat patients with cancer. Given the unique imipridone core chemical structure of ONC201, we synthesized a series of analogs to identify additional compounds with distinct therapeutic properties. Several imipridones with a broad range of in vitro potencies were identified in an exploration of chemical derivatives. Based on in vitro potency in human cancer cell lines and lack of toxicity to normal human fibroblasts, imipridones ONC206 and ONC212 were prioritized for further study. Both analogs inhibited colony formation, and induced apoptosis and downstream signaling that involves the integrated stress response and Akt/ERK, similar to ONC201. Compared to ONC201, ONC206 demonstrated improved inhibition of cell migration while ONC212 exhibited rapid kinetics of activity. ONC212 was further tested in >1000 human cancer cell lines in vitro and evaluated for safety and anti-tumor efficacy in vivo. ONC212 exhibited broad-spectrum efficacy at nanomolar concentrations across solid tumors and hematological malignancies. Skin cancer emerged as a tumor type with improved efficacy relative to ONC201. Orally administered ONC212 displayed potent anti-tumor effects in vivo, a broad therapeutic window and a favorable PK profile. ONC212 was efficacious in vivo in BRAF V600E melanoma models that are less sensitive to ONC201. Based on these findings, ONC212 warrants further development as a drug candidate. It is clear that therapeutic utility extends beyond ONC201 to include additional imipridones.

The strong association of HLA-DR2b (DRB1*1501) with multiple sclerosis (MS) suggests this molecule as prime target for specific immunotherapy. Inhibition of HLA-DR2b–restricted myelin-specific T cells has the potential to selectively prevent CNS pathology mediated by these MHC molecules without undesired global immunosuppression. In this study, we report development of a highly selective small molecule inhibitor of peptide binding and presentation by HLA-DR2b. PV-267, the candidate molecule used in these studies, inhibited cytokine production and proliferation of myelin-specific HLA-DR2b–restricted T cells. PV-267 had no significant effect on T cell responses mediated by other MHC class II molecules, including HLA-DR1, -DR4, or -DR9. Importantly, PV-267 did not induce nonspecific immune activation of human PBMC. Lastly, PV-267 showed treatment efficacy both in preventing experimental autoimmune encephalomyelitis and in treating established disease. The results suggest that blocking the MS-associated HLA-DR2b allele with small molecule inhibitors may be a promising therapeutic strategy for the treatment of MS.

ONC201 is the founding member of a novel class of anti-cancer compounds called imipridones that is currently in Phase II clinical trials in multiple advanced cancers. Since the discovery of ONC201 as a p53-independent inducer of TRAIL gene transcription, preclinical studies have determined that ONC201 has anti-proliferative and pro-apoptotic effects against a broad range of tumor cells but not normal cells. The mechanism of action of ONC201 involves engagement of PERK-independent activation of the integrated stress response, leading to tumor upregulation of DR5 and dual Akt/ERK inactivation, and consequent Foxo3a activation leading to upregulation of the death ligand TRAIL. ONC201 is orally active with infrequent dosing in animals models, causes sustained pharmacodynamic effects, and is not genotoxic. The first-in-human clinical trial of ONC201 in advanced aggressive refractory solid tumors confirmed that ONC201 is exceptionally well-tolerated and established the recommended phase II dose of 625 mg administered orally every three weeks defined by drug exposure comparable to efficacious levels in preclinical models. Clinical trials are evaluating the single agent efficacy of ONC201 in multiple solid tumors and hematological malignancies and exploring alternative dosing regimens. In addition, chemical analogs that have shown promise in other oncology indications are in pre-clinical development. In summary, the imipridone family that comprises ONC201 and its chemical analogs represent a new class of anti-cancer therapy with a unique mechanism of action being translated in ongoing clinical trials.

Amyloid beta-peptide (Abeta) is implicated as the major causative agent in Alzheimer's disease (AD). Abeta is produced by the processing of the amyloid precursor protein (APP) by BACE1 (beta-secretase) and gamma-secretase. Many inhibitors have been developed for the secretases. However, the inhibitors will interfere with the processing of not only APP but also of other secretase substrates. In this study, we describe the development of inhibitors that prevent production of Abeta by specific binding to the beta-cleavage site of APP. We used the hydropathic complementarity (HC) approach for the design of short peptide inhibitors. Some of the HC peptides were bound to the substrate peptide (Sub W) corresponding to the beta-cleavage site of APP and blocked its cleavage by recombinant human BACE1 (rhBACE1) in vitro. In addition, HC peptides specifically inhibited the cleavage of Sub W, and not affecting other BACE1 substrates. Chemical modification allowed an HC peptide (CIQIHF) to inhibit the processing of APP as well as the production of Abeta in the treated cells. Such novel APP-specific inhibitors will provide opportunity for the development of drugs that can be used for the prevention and treatment of AD with minimal side effects.

A kinase-anchoring proteins (AKAPs) coordinate cAMP-mediated signaling by binding and localizing cAMP-dependent protein kinase (PKA), using an amphipathic helical docking motif. Peptide disruptors of PKA localization that mimic this helix have been used successfully to assess the involvement of PKA in specific signaling pathways. However, these peptides were developed as disruptors for the type II regulatory subunit (RII) even though both RI and RII isoforms can bind to AKAPs and have discrete functions. To evaluate the effects of each localized isoform, we designed peptides that specifically bind to either RI or RII. Using a peptide array, we have defined the minimal binding sequence of dual specific-AKAP 2 ( d -AKAP2), which binds tightly to both RI and RII. Side-chain requirements for affinity and isoform specificity were evaluated by using a peptide substitution array where each position along the A kinase binding domain of d -AKAP2 was substituted by the other 19 l -amino acids. This array comprises 513 single-site substitution analogs of the d -AKAP2 sequence. Peptides containing single and multiple mutations were evaluated in a quantitative fluorescence binding assay and a cell-based colocalization assay. This strategy has allowed us to design peptides with high affinity ( K D = 1–2 nM) and high specificity for RIα versus RIIα. These isoform-specific peptides will be invaluable tools to evaluate functional differences between localized RI and RII PKA and are RIα-specific disruptors. This array-based analysis also provides a foundation for biophysical analysis of this docking motif.

Imidazole and oxazole derivatives 1 to 4 were designed and prepared as dipeptide mimetics to replace the Ser-Leu dipeptide sequence of Ro-25-9980 (Ac-(Cha)-RAMA- S - L -NH 2 ), a peptidic inhibitor of antigen binding to major histocompatibility complex (MHC) class II DR molecules linked to rheumatoid arthritis (RA). The most potent analog in binding assays (IC 50 = 30 nM in DRB1*0401 binding; 1.6 times as potent as Ro 25-9980) was 16 , Ac-(Cha)RAMA-( S ) S - Ψ (oxazole)- L -NH 2 . The SAR of peptide hybrids 10 to 24 , prepared by incorporating the dipeptide mimetics 1 to 4 is discussed. Of these hybrids, 23 and 24 , analogs that incorporated the imidazole and oxazole mimetics as well as optimized variants at positions 3 to 5, were found to have 70 to 80 nM binding affinity comparable to the parent peptide in DRB1*0401 binding and were also active in DRB1*0101 binding, while being resistant to proteolysis by cathepsin B. Both of these compounds showed inhibitory activity in an antigen-stimulated T-cell pro...

We previously identified a novel, potent anti-cancer small molecule ONC201, which upregulates the integrated stress response (ISR) through ATF4/CHOP/DR5 and acts as a dual inactivator of Akt and ERK, leading to TRAIL gene activation. After completing a first-in-human phase I clinical trial that revealed exceptional safety, therapeutic pharmacokinetic (PK) profile and tumor engagement, ONC201 is under investigation in several advanced cancer Phase I/II trials. Given the unique imipridone core chemical structure of ONC201, we synthesized a family of analogues in an effort to identify additional chemical family members with distinct therapeutic properties. Based on in vitro potency improvements in human cancer cell lines and therapeutic window approximations with normal human fibroblasts, select analogues were investigated in animals for toxicity, maximum tolerated dose (MTD), and antitumor efficacy. ONC212 is one of the most promising new imipridones that was further evaluated to establish the PK profile, oral bioavailability, and efficacy in tumor types that are less sensitive to ONC201. Compared to ONC201, we noted distinct and more rapid kinetics of activity as well as improved potency in multiple human cancer cell lines in vitro. ONC212 has a broad therapeutic window, an acceptable PK profile, and is orally well-tolerated in mice. With no evidence of toxicity at efficacious doses in both colon and triple negative breast cancer, we have begun further evaluation of antitumor efficacy studies in ONC201-resistant tumor types. Efficacy studies with ONC212 are ongoing in melanoma models that are sensitive to ONC212 but less sensitive to ONC201 in vitro. Preliminary data indicates potent tumor growth reduction by ONC212 in vivo in ONC201-resistant melanoma xenografts. With a wide safety margin, potent antitumor activity in ONC201-insenstive tumors, and drug-like characteristics, ONC212 is being further developed as a drug candidate from the new imipridone class of compounds that complements the spectrum of activity of ONC201. Citation Format: Jessica Wagner, C. Leah Kline, Gary Olson, Bhaskara Nallaganchu, Richard Pottorf, Varun Prabhu, Martin Stogniew, Joshua Allen, Wafik El-Deiry. Preclinical evaluation of the imipridone family of small molecules, including analogues of clinical-stage anti-cancer small molecule ONC201, reveals potent anti-cancer effects of ONC212 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3245. doi:10.1158/1538-7445.AM2017-3245

The X-ray crystal structure of a complex between the human class II major histocompatibility complex (MHC) protein HLA-DR1 and a bispyrrolinone−peptide hybrid ligand has been determined to 2.7 A resolution. The bispyrrolinone segment of the ligand closely mimics the polyproline type II conformation of peptide ligands bound to class II MHC molecules, emphasizing the considerable versatility of this peptidomimetic scaffold. Most hydrogen bonds conserved in all peptide/class II complexes are formed, and the side chains of the bispyrrolinone segment project into the same spaces as those occupied by side chains of bound peptides. Molecular modeling used in the design of the hybrid ligand was remarkably accurate in predicting the observed molecular interactions.

1,2,5-Thiadiazolidin-3-one 1,1-dioxide derivatives (±)-1a – d and (±)-2 were designed by molecular modeling as MHC (major histocompatibility complex) class-II inhibitors. They were prepared from the unsymmetrically N,N′-disubstituted acyclic sulfamides (±)-4a – d (Scheme 1) and (±)-11 (Scheme 2). These N-alkyl-N′-arylsulfamide precursors were synthesized by nucleophilic substitution of either a sulfamoyl-chloride or a N-sulfamoyloxazolidinone. Extension of base-induced cyclization methods from aliphatic to aromatic sulfamides gave access to the desired target molecules. The N-alkyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide derivatives (±)-3a – c were also prepared by the oxazolidinone route (Scheme 4) for coupling to a tetrapeptide fragment. The X-ray crystal structure of 1,2,5-thiadiazolidin-3-one 1,1-dioxide (±)-21a was solved, and the directionality of the H-bond donor (N−H) and acceptor (SO2) groups of the cyclic scaffold determined (Figs. 1 and 2). The pKa value of the N−H group in (±)-21a was determined by 1H-NMR titration as 11.9 (Fig. 3). Compounds (±)-1a – d were shown to inhibit competition peptide binding to HLA-DR4 molecules in the single-digit millimolar concentration range.

The design and synthesis of two pyrrolinone−peptide hybrid ligands (3 and 20) for the rheumatoid arthritis-associated class II MHC HLA-DR1 protein are described. The hybrids incorporate bispyrrolinones 4 and 21 as tetrapeptide mimics for amino acids VKQN (residues 309−312) of the virus hemagglutinin peptide HA 306−318 (PKYVKQNTLKLAT). Ligand construction employed our polypyrrolinone synthetic protocol, in conjunction with Fmoc-based solid-phase peptide synthesis. Bioaffinity studies reveal that hybrid ligand 3 bound the HLA-DR1 protein with affinity (IC50 = 137 nM) comparable to those of both the native HA 306−318 peptide (IC50 = 89 nM) and a control peptide (IC50 = 176 nM). This result demonstrates that the polypyrrolinone scaffold can be employed in the construction of bioactive peptide hybrid ligands, thus considerably expanding the scope and utility of the pyrrolinone scaffold.

We have identified a heptapeptide with high affinity to rheumatoid arthritis-associated class II major histocompatibility (MHC) molecules. Using a model of its interaction with the class II binding site, a variety of mimetic substitutions were introduced into the peptide. Several unnatural amino acids and dipeptide mimetics were found to be appropriate substituents and could be combined into compounds with binding affinities comparable to that of the original peptide. Compounds were designed that were several hundred-fold to more than a thousand-fold more potent than the original peptide in inhibiting T-cell responses to processed protein antigens presented by the target MHC molecules. Peptidomimetic compounds of this type could find therapeutic use as MHC-selective antagonists of antigen presentation in the treatment of autoimmune diseases.

A compendium of compounds designed as dipeptide mimetics was collected from the literature. Conformational space available to these molecules was evaluated to obtain distance and torsion angle parameters to aid in selection of mimetics for specific target peptides or to explore diversity strategies. Conformations were searched using the RandomSearch algorithm in SYBYL. Data were collected for conformations of each molecule falling within 5 kcal/mol of the minimum. The distance between capping groups on the N- and C-termini of the molecules was measured as well as the pseudotorsion angle about a virtual bond between these two points. Molecules are classified based on the torsion angle space occupied and range of distances spanned by the resulting conformations. A large percentage of the dipeptide mimetics studied here have redundant conformational properties. The distribution of distances for all molecules covers an overall range of 3–15 A, the majority falling between 5–8 A. The angles for the majority of the molecules cover a wide range of torsional space with essentially no gaps in the values they can occupy, although these molecules can be subdivided by the average distance spanned by the allowed conformations. A smaller group of molecules have torsion angles that are restricted to a range of ±60° about the cis position (0°). Representative examples of each group are shown. We conclude that despite the significant effort to devise unique molecular structures as dipeptide mimetics, there is a need for more conformationally restricted compounds to mimic specific peptide conformations, and to complement molecular diversity strategies. © 1997 John Wiley & Sons, Inc. Biopoly 43: 191–217, 1997

The design and synthesis of peptide mimetics of thyrotropin-releasing hormone (TRH) in which the peptide backbone is entirely replaced by a cyclohexane framework are described. The cis-1,3,5-trisubstituted ring was expected to permit key pharmacophoric groups to adopt conformations consistent with proposed bioactive conformations of the peptide. Compounds were synthesized by a stereoselective synthesis starting from L-glutamic acid. In a behavioral model of cognition in which TRH is active, the mimetics are potent, active compounds, exhibiting oral activity. One analog (26, (1S,3R,5(2S),5S)-5-[[5-oxo-1-(phenylmethyl)-2-pyrrolidinyl]-methyl]-5- [(1H-imidazol-5-yl)methyl]cyclohexaneacetamide) was radiolabeled for binding studies and evaluated in other binding assays and pharmacological tests. Competition binding of 26 vs [3H]MeTRH to rat brain slices suggests a two-site model for ligand binding with IC50's of 1 microM and 3 mM. Direct binding of [3H]-26 shows a biphasic curve with IC50's of 80 and 49 microM, respectively. Further studies would be needed to establish a link between the novel binding site(s) and the behavioral activity of 26 and TRH analogs.

Pancreatic cancer is one of the most deadly types of cancer with five-year survival rate of ∼6%. This poor prognosis is attributed to aggressive growth of the tumor cells, metastasis at an early stage and resistance to standard chemotherapy. Therefore, finding new treatments and improving outcomes of pancreatic cancer patients have been high priorities. ONC201 is a small molecule that selectively targets a broad range of tumor types tested. It is currently in phase I/II clinical trials for advanced solid, hematopoietic, and lymphoid tumors. The ONC201 analogue, ONC212, is in preclinical development for certain cancers that are not lead indications for the parent compound ONC201. We examined the efficacy of ONC201 and ONC212 in a panel of human pancreatic cancer cell lines. Among seven cell lines tested, three cell lines were relatively insensitive to ONC201, with IC50 values of 100 ìM or greater. However, these cell lines showed greater sensitivity to ONC212 with IC50 values of 31-56 ìM. We compared ONC201-resistant PANC-1 cells and ONC201-sensitive HPAF-II cells. Both ONC201 and ONC212 induced apoptosis in HPAF-II cells, as assessed by PARP cleavage, while PARP cleavage was detected only when PANC-1 cells were treated with ONC212 but not ONC201. We are currently evaluating the efficacy of ONC201 and ONC212 in a panel of patient-derived low passage pancreatic cancer cell lines. We found a correlation between high expression levels of RTKs (c-MET, ALK, EGFR, IGFR, HER2) and decreased sensitivity to ONC201 in pancreatic cancer cell lines. We investigated the effect of ONC201 on EGFR and IGFR, which are highly expressed in PANC-1 and found that ONC201 does not inhibit receptor activation by the specific growth factors. We are studying the effects of ONC201 and ONC212 on RTKs and their signal transduction pathways. Lastly, since aggressive drug-resistant pancreatic cancer cells express high levels of RTKs, we are developing a rationale combining ONC201/ONC212 with specific small molecule RTK inhibitors such as crizotinib or lapatinib. We are exploring these combination treatments using cell lines, organoids and PDX models to unravel specific therapy options for therapy-refractory pancreatic cancer cells. Our goal is to provide the preclinical rationale for clinical trials of ONC201 or ONC212 as mono-agents or in combination with other therapies for pancreatic cancer patients. Citation Format: Avital Lev, Jessica Wagner, David T. Dicker, Martin Stogniew, Joshua E. Allen, Lee Schalop, Wolfgang Oster, Gary L. Olson, Wafik S. El-Deiry. ONC212 exhibits increased cytotoxicity relative to ONC201 in a subset of human pancreatic cancer cell lines. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4826.

TRAIL is an endogenous protein that initiates apoptosis selectively in cancer without toxic side effects, prompting interest in therapeutic modulation. We previously screened for small molecules that could upregulate the endogenous TRAIL gene to trigger apoptosis and restore anti-tumor immunity within tumor cells in a p53-independent manner. We showed that ONC201 (previously referred to as TIC10) is a dual inactivator of Akt and ERK, leading to nuclear translocation of Foxo3a and TRAIL gene activation (Allen et al., Science Translational Medicine, 2013). We recently found that ONC201 causes an early-stage upregulation of the integrated stress response through ATF4/CHOP/DR5 (Kline et al., Science Signaling, in press) and can inhibit cancer stem cell self-renewal (Prabhu et al., Cancer Research, 2015). ONC201 recently completed its first-in-man phase I clinical trial and several other trials in select advanced cancers are ongoing (NCT02250781, NCT02324621, NCT02420795, NCT02392572, NCT02609230, NCT02525692, NCT02038699). Leveraging the unique pharmacophore of ONC201, we synthesized ONC201 analogues in search for compounds with distinct therapeutic properties. After establishing the importance of the pyrido[3,4-e]pyrimidinone core structure of ONC201 in its anti-tumor activity (Wagner et al., Oncotarget, 2014), we performed detailed structure activity relationship (SAR) studies. We evaluated several ONC201 analogues with differing N-substituents around the core structure. Certain ONC201 analogues exhibit more rapid kinetics of activity and lowered IC50 values in some human cancer cell lines in vitro. Interim results of ONC212 sensitivity profiling in >100 genetically annotated cell lines from the Genomic of Drug Sensitivity in Cancer collection have corroborated this improvement in potency. One analogue, ONC212, has demonstrated compelling efficacy against several tumor types in vivo with no evidence of toxicity at therapeutic doses. Furthermore, in vitro mechanism studies have demonstrated overlap between ONC201- and ONC212-mediated signaling in tumor cells that includes activation of the integrated stress response. With a wide safety margin, distinct pharmacokinetics (PK), and robust potency, ONC212 is being developed as the next drug candidate from the new class of compounds defined by the novel pharmacophore of ONC201 in indications that complement the parent compound's use spectrum. Citation Format: Jessica Wagner, Gary Olson, Nallaganchu Rao Bhaskara, Richard S. Pottorf, Garnett J. Mathew, Cyril H. Benes, Rohinton Tarapore, Martin Stogniew, Lee Schalop, Wolfgang Oster, Josh E. Allen, Wafik S. El-Deiry. Structure-activity relationships and mechanistic analysis of analogues of the clinical-stage anti-cancer small molecule ONC201. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 349.

e23161Background: We previously screened for small molecules that could stimulate anti-tumor immunity within tumor cells through p53-independent TRAIL upregulation. TRAIL initiates apoptosis select...

Peptide mimetics of thyrotropin-releasing hormone (TRH) in which the peptide backbone is replaced by cyclohexane were synthesized from the cyclohexenone precursor 7. The aromatic side chains of the mimetics were derived from the corresponding aldehydes which were attached to the cyclohexenone via the Wittig reagent 8. The TRH mimetics are active in a mouse model of cognitive performance.

The cyclic peptide 1 , containing a 2,7-disubstituted naphthalene spacer, was designed to mimic an exposed Ω-loop present in interleukin-1α, an important mediator of immune and inflammatory responses. The synthesis of this cyclic peptide was accomplished via solution phase fragment condensation methodology. The three dimensional characterization using 2D-NMR techniques revealed it to be an excellent mimic for the Ω-loop sequence 41–48 in interleukin -1α.

The cyclic peptide 1 , containing a 2,7-disubstituted naphthalene spacer, was designed to mimic an exposed Ω-loop present in interleukin-1α, an important mediator of immune and inflammatory responses. The synthesis of this cyclic peptide was accomplished via solution phase fragment condensation methodology. The three dimensional characterization using 2D-NMR techniques revealed it to be an excellent mimic for the Ω-loop sequence 41–48 in interleukin -1α.

The design and synthesis of peptide mimetics of thyrotropin-releasing hormone (TRH) in which the peptide backbone is entirely replaced by a cyclohexane framework are described. The cis-1,3,5-trisubstituted ring was expected to permit key pharmacophoric groups to adopt conformations consistent with proposed bioactive conformations of the peptide. Compounds were synthesized by a stereoselective synthesis starting from L-glutamic acid. In a behavioral model of cognition in which TRH is active, the mimetics are potent, active compounds, exhibiting oral activity. One analog (26, (1S,3R,5(2S),5S)-5-[[5-oxo-1-(phenylmethyl)-2-pyrrolidinyl]-methyl]-5- [(1H-imidazol-5-yl)methyl]cyclohexaneacetamide) was radiolabeled for binding studies and evaluated in other binding assays and pharmacological tests. Competition binding of 26 vs [3H]MeTRH to rat brain slices suggests a two-site model for ligand binding with IC50's of 1 microM and 3 mM. Direct binding of [3H]-26 shows a biphasic curve with IC50's of 80 and 49 microM, respectively. Further studies would be needed to establish a link between the novel binding site(s) and the behavioral activity of 26 and TRH analogs.

1,2,5-Thiadiazolidin-3-one 1,1-dioxide derivatives (±)-1a – d and (±)-2 were designed by molecular modeling as MHC (major histocompatibility complex) class-II inhibitors. They were prepared from the unsymmetrically N,N′-disubstituted acyclic sulfamides (±)-4a – d (Scheme 1) and (±)-11 (Scheme 2). These N-alkyl-N′-arylsulfamide precursors were synthesized by nucleophilic substitution of either a sulfamoyl-chloride or a N-sulfamoyloxazolidinone. Extension of base-induced cyclization methods from aliphatic to aromatic sulfamides gave access to the desired target molecules. The N-alkyl-1,2,5-thiadiazolidin-3-one 1,1-dioxide derivatives (±)-3a – c were also prepared by the oxazolidinone route (Scheme 4) for coupling to a tetrapeptide fragment. The X-ray crystal structure of 1,2,5-thiadiazolidin-3-one 1,1-dioxide (±)-21a was solved, and the directionality of the H-bond donor (N−H) and acceptor (SO2) groups of the cyclic scaffold determined (Figs. 1 and 2). The pKa value of the N−H group in (±)-21a was determined by 1H-NMR titration as 11.9 (Fig. 3). Compounds (±)-1a – d were shown to inhibit competition peptide binding to HLA-DR4 molecules in the single-digit millimolar concentration range.

A nine-membered-ring lactam system (1) has been chosen as a framework for the development of non-peptide molecules to mimic structural features of peptide and protein {beta}-turns. The synthesis of model di- and tetrapeptide mimetics starting from 1,5-cyclooctadiene derivatives is reported. In the model dipeptide mimetic (9), the amide linkages is trans (NMR, X-ray) and functional groups at positions adjacent to the lactam amide bond correspond closely to the side-chain positions of residues i + 1 and i + 2 of classical type II{prime} {beta}-turns. In the model tetrapeptide mimetic (30), all four side chains of low-energy trans amide conformers of the mimetic are well matched to their peptide counterparts.

We previously identified TRAIL-inducing compound 10 (TIC10), also known as NSC-350625, as a small molecule being developed under the name ONC201 that has potent anti-tumor efficacy and a benign safety profile in preclinical cancer models. Further investigation of the preclinical profile of this drug candidate led in early 2014 to the FDA acceptance of the investigational drug application (IND) for oral ONC201 to treat patients with advanced cancer. The initially disclosed chemical structure of ONC201 provided by Stahle et. al in an expired patent was described as an imidazo[1,2-a]pyrido[4,3-d]pyrimidine derivative. Our first report of its anticancer activity by Allen et. al. included mass spectrometry and 1H NMR that indicated both were consistent with the structure depicted by Stahle et. al and the National Cancer Institute. A recent publication reported that the structure of ONC201 differs from the initial description and is in fact an angular [3,4-e] isomer of the previously depicted structure. Here, we report X-ray crystallography and other structural studies of ONC201 produced by Oncoceutics in a dihydrochloride salt form for clinical use that confirm the angular [3,4-e] structure and indicate that the material is not a mixture of the two isomers. Furthermore, we confirm that although fragmentation by mass spectrometry for the isomers is identical, the angular [3,4-e] isomer can be definitively identified as ONC201 by implementing specific various spectroscopy techniques to identify differences between ONC201 and the linear isomer. In accordance with our structural analysis, in vitro activity assays in cancer cells indicate that the previously disclosed anti-cancer activity and mechanism of action are indeed associated exclusively with the [3,4-e] structure and not the [4,3-d] linear isomer. Together these studies confirm the angular [3,4-e] structure of ONC201 as the highly active and pure anti-cancer drug candidate that was utilized in prior preclinical pharmacology studies and is now entering clinical trials in several oncology indications. Citation Format: Jessica Wagner, Christina Leah Kline, Richard S. Pottorf, Bhaskara Rao Nallaganchu, Gary L. Olson, David T. Dicker, Joshua E. Allen, Wafik S. El-Deiry. Cytotoxicity, biochemical activity, and structural analysis of ONC201 and comparisons to a biologically inactive isomer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4499. doi:10.1158/1538-7445.AM2015-4499

Imidazole and oxazole derivatives 1 to 4 were designed and prepared as dipeptide mimetics to replace the Ser-Leu dipeptide sequence of Ro-25-9980 (Ac-(Cha)-RAMA-S-L-NH2), a peptidic inhibitor of antigen binding to major histocompatibility complex (MHC) class II DR molecules linked to rheumatoid arthritis (RA). The most potent analog in binding assays (IC50 = 30 nM in DRB1*0401 binding; 1.6 times as potent as Ro 25-9980) was 16, Ac-(Cha)RAMA-(S)S-psi(oxazole)-L-NH2. The SAR of peptide hybrids 10 to 24, prepared by incorporating the dipeptide mimetics 1 to 4 is discussed. Of these hybrids, 23 and 24, analogs that incorporated the imidazole and oxazole mimetics as well as optimized variants at positions 3 to 5, were found to have 70 to 80 nM binding affinity comparable to the parent peptide in DRB 1*0401 binding and were also active in DRB1*0101 binding, while being resistant to proteolysis by cathepsin B. Both of these compounds showed inhibitory activity in an antigen-stimulated T-cell proliferation assay, indicating their potential to suppress autoimmune responses and as leads for therapeutic agents to treat RA.

Molecular features of ligand binding to MHC class II HLA-DR molecules have been elucidated through a combination of peptide structure-activity studies and structure-based drug design, resulting in analogues with nanomolar affinity in binding assays. Stabilization of lead compounds against cathepsin B cleavage by N-methylation of noncritical backbone NH groups or by dipeptide mimetic substitutions has generated analogues that compete effectively against protein antigens in cellular assays, resulting in inhibition of T-cell proliferation. Crystal structures of four ternary complexes of different peptide mimetics with the rheumatoid arthritis-linked MHC DRB10401 and the bacterial superantigen SEB have been obtained. Peptide-sugar hybrids have also been identified using a structure-based design approach in which the sugar residue replaces a dipeptide. These studies illustrate the complementary roles played by phage display library methods, peptide analogue SAR, peptide mimetics substitutions, and structure-based drug design in the discovery of inhibitors of antigen presentation by MHC class II HLA-DR molecules.

Previous work indicates that both the C-terminal phenylalanine amide and the tryptophan moieties of cholecystokinin (CCK) are critical pharmacophores for interaction with either the A or B receptor subtypes. We have examined a series of analogs of Ac-CCK-7 [Ac-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe33-NH2] (2) in which the phenyl ring of the C-terminal Phe-NH2 has been modified. Compounds were assessed in binding assays using homogenated rat pancreatic membranes and bovine striatum as the source of CCK-A and CCK-B receptors respectively and for anorectic activity after intraperitoneal administration to rats. Substitution of a number of cycloalkyl or bicyclic aryl moieties for the phenyl ring of phenylalanine33 including cyclopentyl (20), cyclohexyl (21), cyclooctyl (23), 2-(5,6,7,8-tetrahydro)naphthyl (26), 2-naphthyl (27), and 1-naphthyl (29) led to analogs with 10-70 times the anorectic potency of 2. The anorectic activity of 21 was blocked by the specific CCK-A receptor antagonist MK-329. Other bulky aliphatic groups in place of the phenylalanine33 aromatic ring such as isopropyl, 2-adamantyl and cyclohexylmethyl gave derivatives similar to 2 in potency. While most of the new compounds were comparable to CCK in binding assays, 23, 26, 27 and 29 were exceptionally potent with IC50s 10(-11)-10(-14) M in the pancreas. Compounds 23 and 29 were further evaluated for their ability to stimulate amylase secretion and found to have potencies similar to that of CCK. The dissociation between potency in the binding and amylase secretion assays suggests that they may interact with a high affinity binding site which is not coupled to amylase secretion. We conclude that CCK receptors possess a generous hydrophobic pocket capable of accommodating large alkyl groups in place of the side chain of phenylalanine33 and that the pharmacological profile of CCK analogs can be tailored by appropriate exploitation of this finding.

Synthese des composes du titre et en particulier de la piquindone a partir d'arecoline ou d'arecolone

A hypothetical model of the interaction of antipsychotic drugs with the dopamine receptor is described. This three-dimensional molecular model has been developed on the basis of plausible intermolecular interactions between pharmacophoric groups of diverse types of antipsychotic drugs and postulated amino acid side chain substituents of the receptor protein. Three essential binding sites (one possibly required for antagonism) and one lipophilic auxiliary binding site are identified. The geometry is defined via the three-dimensional structures of drugs exhibiting receptor activity, including (R)-apomorphine, (+)-dexclamol, and molindone (whose crystal structure has been determined). A new conformationally rigid pyrrolo[2,3-g]isoquinoline derivative has been designed to conform to the receptor model. The compound (+/-)-1 (2,6-dimethyl-3-ethyl-4,4a,5,6,7,8,8a,9-octahydro-4a,8a-trans-1H-pyrrolo[2,3-g] isoquinolin-4-one; Ro 22-1319) exhibits potent antipsychotic-like activity. The activity is stereospecific, residing in the (-) enantiomer, predicted and confirmed by X-ray crystal structure analysis of (-)-1.HCl to have the 4aR,8aR absolute configuration.

An efficient synthesis of all-(E) vitamin A acetate from 2,2,6-trimethyl-cyclohexanone has been achieved via the intermediacy of 1-(9-acetoxy-3, 7-dimethyl-nona-3,5,7-trien-1-ynyl)-2,2,6-trimethyl-cyclohexanol (25), readily prepared in high yield by allylic rearrangement of tertiary propenols with glacial acetic acid. The key step in the synthesis is the transformation of 25 to the unsaturated ketone 27 (9-acetoxy-3,7-dimethyl-1-(2,6,6-trimethyl-cyclohex-1-enyl)-nona-3,5,7-trien- 2-one) using a novel vanadium(V)-catalysed rearrangement reaction. The carbonyl in 27 affords the means for the essential isomerization of the adjacent double bond to the (E) isomer and the product is readily transformed into the polyene by reduction and elimination. An overall yield of 18–31% of vitamin A acetate from 2,2,6-trimethyl-cyclohexanone has been realized.

The experiment described here studies a series of reactions employed in the synthesis of a number of coordination compounds of cobalt(II) and cobalt(III).