The effect of the potent and selective poly(ADP-ribose) (PAR) polymerase-1 [and PAR polymerase-2] inhibitor CEP-8983 on the ability to sensitize chemoresistant glioblastoma (RG2), rhabdomyosarcoma (RH18), neuroblastoma (NB1691), and colon carcinoma (HT29) tumor cells to temozolomide-and camptothecin-induced cytotoxicity, DNA damage, and G 2 -M arrest and on the potentiation of chemotherapy-induced myelotoxicity was evaluated using in vitro assays. In addition, the effect of the prodrug CEP-9722 in combination with temozolomide and/or irinotecan on PAR accumulation and tumor growth was also determined using glioblastoma and/or colon carcinoma xenografts relative to chemotherapy alone. CEP-8983 sensitized carcinoma cells to the growth-inhibitory effects of temozolomide and/or SN38 increased the fraction of and/ or lengthened duration of time tumor cells accumulated in chemotherapy-induced G 2 -M arrest and sensitized tumor cells to chemotherapy-induced DNA damage and apoptosis. A granulocyte-macrophage colony-forming unit colony formation assay showed that coincubation of CEP-8983 with temozolomide or topotecan did not potentiate chemotherapy-associated myelotoxicity. CEP-9722 (136 mg/kg) administered with temozolomide (68 mg/kg for 5 days) or irinotecan (10 mg/kg for 5 days) inhibited significantly the growth of RG2 tumors (60%) or HT29 tumors (80%) compared with temozolomide or irinotecan monotherapy, respectively. In addition, CEP-9722 showed ''stand alone'' antitumor efficacy in these preclinical xenografts. In vivo biochemical efficacy studies showed that CEP-9722 attenuated PAR accumulation in glioma xenografts in a dose-and time-related manner. These data indicate that CEP-8983 and its prodrug are effective chemosensitizing agents when administered in combination with select chemotherapeutic agents against chemoresistant tumors. [Mol Cancer Ther 2007;6(8):2290-302]

TL1A is an attractive therapeutic target for the treatment of mucosal inflammation associated with inflammatory bowel disease (IBD) and asthma. Blockade of the TL1A pathway has been shown to reduce inflammatory responses while leaving baseline immunity intact, and to be beneficial in animal models of colitis and asthma. Given the therapeutic potential of blocking this pathway in IBD and asthma, we developed C03V, a human antibody that binds with high affinity to soluble and membrane-bound TL1A. In an assay measuring apoptosis induced by exogenous TL1A, C03V was 43-fold more potent than the next most potent anti-TL1A antibody analyzed. C03V also potently inhibited endogenous TL1A activity in a primary cell-based assay. This potency was linked to the C03V-binding epitope on TL1A, encompassing the residue R32. This residue is critical for the binding of TL1A to its signaling receptor DR3 but not to its decoy receptor DcR3, and explains why C03V inhibited TL1A-DR3 binding to a much greater extent than TL1A-DcR3 binding. This characteristic may be advantageous to preserve some of the homeostatic functions of DcR3, such as TL1A antagonism. In colitis models, C03V significantly ameliorated microscopic, macroscopic and clinical aspects of disease pathology, and in an asthma model it significantly reduced airways inflammation. Notable in both types of disease model was the reduction in fibrosis observed after C03V treatment. C03V has the potential to address unmet medical needs in asthma and IBD.

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The optimization of the dihydronaphthyl[3,4-a]pyrrolo[3,4-c]carbazole-5-one R(2) and R(12) positions led to the identification of the first MLK1 and MLK3 subtype-selective inhibitors within the MLK family. Compounds 14 (CEP-5104) and 16 (CEP-6331) displayed good potency for MLK1 and MLK3 inhibition with a greater than 30- to 100-fold selectivity for related family members MLK2 and DLK. Compounds 14 and 16 were orally active in vivo in a mouse MPTP biochemical efficacy model that was comparable to the first-generation pan-MLK inhibitor 1 (CEP-1347). The MLK1 structure-activity relationships were supported by the first-reported X-ray crystal structure of MLK1 bound with 16.

Reslizumab and mepolizumab are recently approved monoclonal antibodies for the treatment of severe (uncontrolled) eosinophilic asthma. Both are effective in neutralizing the function of interleukin-5 (IL-5). This study is the first to compare the binding affinity and in vitro potency of both antibodies in head-to-head assays. Two assays assessed binding affinity (using the equilibrium dissociation constant [K D ]) of each drug for human IL-5. In the Biacore surface plasmon resonance assay, the association constant (k on ) values for human IL-5 for reslizumab and mepolizumab were 3.93 × 10 6 and 1.83 × 10 5 , respectively. The dissociation constant (k off ) values were 4.29 × 10 −4 and 2.14 × 10 −4 , respectively. Calculated K D values for human IL-5 for reslizumab and mepolizumab were 109 and 1,170 pM, respectively, representing an approximately 11-fold stronger binding affinity with reslizumab. In the Kinetic Exclusion Assay, the k on values for human IL-5 for reslizumab and mepolizumab were 3.17 × 10 6 and 1.32 × 10 5 , respectively. The k off values were 1.36 × 10 −5 and 1.48 × 10 −5 , respectively. Measured K D values for human IL-5 for reslizumab and mepolizumab were 4.3 and 112 pM, respectively, representing an approximately 26-fold stronger binding affinity for reslizumab. A human-IL-5-dependent cell proliferation assay was developed to assess in vitro potency, based on a human cell line selected for enhanced surface expression of IL-5 receptor-alpha and consistent proliferation response to IL-5. The concentration at which 50% inhibition occurred (IC 50 ) was determined for both antibodies. Reslizumab and mepolizumab inhibited IL-5-dependent cell proliferation, with IC 50 values of approximately 91.1 and 286.5 pM, respectively, representing on average 3.1-fold higher potency with reslizumab. In conclusion, comparative assays show that reslizumab has higher affinity binding for and in vitro potency against human IL-5 compared with mepolizumab. However, these results do not take into consideration the different methods of administration of reslizumab and mepolizumab.

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Polymerase-1 Inhibitors. -High throughput screening of an internal library identifies pyrrolocarbazole (VIIa) as a potent PARP-1 inhibitor. Structural modifications around this novel PARP-1 template identifies the key pharmacophore elements necessary for PARP-1 inhibition. The cyclopentyl ring fits into a steric pocket with the enzyme and is required for potency. The indole NH-group forms a significant H-bond with PARP-1. The truncated pyrrole imide (XIb) is equipotent to (VIIa), indicating that the B-ring is not required, and represents a novel small molecule PARP-1 scaffold. -(TAO*, M.; PARK, C. H.; BIHOVSKY, R.; WELLS, G. J.; HUSTEN, J.; ATOR, M. A.; HUDKINS, R. L.; Bioorg. Med. Chem. Lett. 16 (2006) 4, 938-942; Cephalon Inc., West Chester, PA 19380, USA; Eng.) -H. Hoennerscheid

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