No abstract

Inhibition of the bromodomain of the transcriptional regulator CBP/P300 is an especially interesting new therapeutic approach in oncology. We recently disclosed in vivo chemical tool 1 (GNE-272) for the bromodomain of CBP that was moderately potent and selective over BRD4(1). In pursuit of a more potent and selective CBP inhibitor, we used structure-based design. Constraining the aniline of 1 into a tetrahydroquinoline motif maintained potency and increased selectivity 2-fold. Structure-activity relationship studies coupled with further structure-based design targeting the LPF shelf, BC loop, and KAc regions allowed us to significantly increase potency and selectivity, resulting in the identification of non-CNS penetrant 19 (GNE-781, TR-FRET IC = 0.94 nM, BRET IC = 6.2 nM; BRD4(1) IC = 5100 nΜ) that maintained good in vivo PK properties in multiple species. Compound 19 displays antitumor activity in an AML tumor model and was also shown to decrease Foxp3 transcript levels in a dose dependent manner.

CpG DNA ͉ cytokines ͉ immune stimulation ͉ innate immunity ͉ immunotherapy

Purpose: Cancer cells can use X-linked inhibitor of apoptosis (XIAP) to evade apoptotic cues, including chemotherapy. The antitumor potential of AEG35156, a novel second-generation antisense oligonucleotide directed toward XIAP, was assessed in human cancer models when given as a single agent and in combination with clinically relevant chemotherapeutics. Experimental Design: AEG35156 was characterized for its ability to cause dose-dependent reductions of XIAP mRNA and protein in vitro and in vivo, to sensitize cancer cell lines to death stimuli, and to exhibit antitumor activity in multiple human cancer xenograft models as a single agent or in combination with chemotherapy. Results: AEG35156 reduced XIAP mRNA levels with an EC 50 of 8 to 32 nmol/L and decreased XIAP protein levels by >80%. Loss of XIAP protein correlated with increased sensitization to tumor necrosis factor^related apoptosis-inducing ligand (TRAIL)^mediated apoptosis in Panc-1 pancreatic carcinoma cells. AEG35156 exhibited potent antitumor activity relative to control oligonucleotides in three human cancer xenograft models (prostate, colon, and lung) and was capable of inducing complete tumor regression when combined with taxanes. Antitumor effects of AEG35156 correlated with suppression of tumor XIAP levels. Conclusions: AEG35156 reduces XIAP levels and sensitizes tumors to chemotherapy. AEG35156 is presently under clinical assessment in multiple phase I trials in cancer patients as a single agent and in combination with docetaxel in solid tumors or cytarabine/idarubicin in leukemia.Chemotherapy is the mainstay of clinical treatment for many solid tumors. However, the development of chemoresistance is a common feature, resulting in a decrease or loss of therapeutic effectiveness. One of the major mechanisms responsible for chemoresistance is the loss of apoptotic sensitivity in cancer cells. Possible causes include alterations in the initiation or execution of the apoptotic machinery, which results from increased activity of antiapoptotic proteins. Novel anticancer therapies that specifically target antiapoptotic mechanisms or that act to lower the apoptotic threshold of cancer cells are in preclinical development or under clinical evaluation (1). An appealing therapeutic candidate target is the X-linked inhibitor of apoptosis (XIAP), a potent antiapoptotic protein whose overexpression and dysfunction is associated with resistance to chemotherapy and radiotherapy (2 -5).Although apoptotic pathways in cells are complex, most seem to converge on a single family of proteases, the caspases that dismantle the cell in an orderly, noninflammatory fashion. The human IAP family, characterized by the presence of one to three baculovirus IAP repeat motifs at the NH 2 terminus of the polypeptide chain (reviewed in refs. 3, 6), are the only known cellular inhibitors of caspases. Specifically, they inhibit two key effector caspases, caspase-3 and caspase-7, and the key initiator caspase, caspase-9, which is responsible for the intrinsic mitochondria...

Oligodeoxyribonucleotides containing CpG dinucleotides (CpG DNAs) are currently being evaluated as novel immunomodulators in clinical trials. Recently, we showed that an accessible 5' end is required for immunostimulatory activity and blocking the 5' end of CpG DNA by conjugation of certain ligands abrogates immunostimulatory activity. Based on these results, we designed and synthesized 3'-3'-linked CpG DNAs that contained two or more identical CpG DNA segments, referred to here as 'immunomers'. The use of solid support bearing diDMT-glyceryl-linker permitted convenient synthesis of immunomers with both segments synthesized simultaneously, giving better yields and purity. The in vitro and in vivo studies suggest that as a result of accessibility to two 5' ends for recognition, immunomers show an enhanced immunostimulatory activity compared with linear CpG DNAs. We also studied the suitability of a number of different linkers for attaching the two segments of immunomers. A C3-linker was found to be optimal for joining the two segments of immunomers. Incorporation of multiple linkers between the two segments of immunomers resulted in different cytokine profiles depending on the nature and number of linkers incorporated. Additionally, the length of immunomer also plays a significant role in inducing immune responses. An immunomer containing 11 nt in each segment showed the highest activity and an 11mer linear CpG DNA failed to stimulate an immune response. These results suggest that immunomers have several advantages over conventional linear CpG DNAs for immunomodulatory activity studies.