Preliminary in vitro and in vivo investigation of a potent platelet derived growth factor receptor (PDGFR) family kinase inhibitor.

Aberrant expression of wild-type and mutant forms of the platelet-derived growth factor receptor (PDGFR) family of receptor tyrosine kinases has been implicated in various oncologic indications such as leukemias, gliomas, and soft tissue sarcomas. Clinically used kinase inhibitors imatinib and sunitinib are potent inhibitors of wild-type PDGFR family members, but show reduced binding to mutant forms. Here we describe compound 5 which binds to both wild-type and oncogenic mutant forms of PDGFR family members, and demonstrates both cellular and in vivo activity.

Heterobivalent agents targeting PSMA and integrin-αvß3.

Differential expression of surface proteins on normal vs malignant cells provides the rationale for the development of receptor-, antigen-, and transporter-based, cancer-selective imaging and therapeutic agents. However, tumors are heterogeneous, and do not always express what can be considered reliable, tumor-selective markers. That suggests development of more flexible targeting platforms that incorporate multiple moieties enabling concurrent targeting to a variety of putative markers. We report the synthesis, biochemical, in vitro, and preliminary in vivo evaluation of a new heterobivalent (HtBv) imaging agent targeting both the prostate-specific membrane antigen (PSMA) and integrin-αvß3 surface markers, each of which can be overexpressed in certain tumor epithelium and/or neovasculature. The HtBv agent was functionalized with either 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) or the commercially available IRDye800CW. DOTA-conjugated HtBv probe 9 bound to PSMA or αvß3 with affinities similar to those of monovalent (Mnv) compounds designed to bind to their targets independently. In situ energy minimization experiments support a model describing the conformations adapted by 9 that enable it to bind both targets. IRDye800-conjugated HtBv probe 10 demonstrated target-specific binding to either PSMA or integrin-αvß3 overexpressing xenografts. HtBv agents 9 and 10 may enable dual-targeted imaging of malignant cells and tissues in an effort to address heterogeneity that confounds many cancer-targeted imaging agents.

Discovery, synthesis, and investigation of the antitumor activity of novel piperazinylpyrimidine derivatives.

Protein kinases play several pertinent roles in cell proliferation, and targeting these proteins has been shown to be a successful strategy toward controlling different malignancies. Despite the great discovery stories during the last two decades, there is still a demand for anticancer small molecules with the potential of being selective on both the protein kinase and/or the cellular level. A series of novel piperazinylpyrimidine compounds were synthesized and tested for their potential to selectively inhibit the growth of certain tumor cell lines included within the NCI-60 cell line panel. MDA-MB-468, a triple-negative/basal-like breast carcinoma, cell line was among the most sensitive cell lines towards compounds 4 and 15. The three most interesting compounds identified in cellular screens (4, 15, and 16) were subjected to kinase profiling and found to have an interesting selective tendency to target certain kinase subfamily members; PDGFR, CK1, RAF and others. Compound 4 showed a selective tendency to bind to and/or inhibit the function of certain KIT and PDGFRA mutants compared to their wild-type isoforms. Piperazinylpyrimidine based derivatives represent a new class of selective kinase inhibitors. Significantly 4 is more potent at inhibiting oncogenic mutant forms of PDGFR family kinases, which is relevant in terms of its potential use in treating tumors that have become resistant to treatment or driven by such mutations. The clinical demand for agents useful in the control of triple-negative/basal-like breast cancer justifies our interest in compound 15 which is a potent growth inhibitor of MDA-MB-468 cell line.

Anti-tumor pyrimidinylpiperazines bind to the prosurvival Bcl-2 protein family member Bcl-XL.

Overexpression of prosurvival or underexpression of pro-death Bcl-2 family proteins can lead to cancer cell resistance to chemotherapy and radiation treatment. Inhibition of the prosurvival Bcl-2 family proteins has become a strategy for cancer therapy and inhibitors are currently being evaluated in the clinic both as single agents and in combination with established drugs. Here we describe the design, synthesis, and evaluation of pyrimidylpiperazines that were discovered to be inhibitors of the prosurvival Bcl-2 protein family member Bcl-XL. This study identified compound 21 which demonstrated a GI(50) value of 8.4 µM against A549 lung adenocarcinoma cells and a binding affinity K(i) value for Bcl-XL of 127 nM.

Latrunculin A and its C-17-O-carbamates inhibit prostate tumor cell invasion and HIF-1 activation in breast tumor cells.

The marine-derived macrolides latrunculins A ( 1) and B, from the Red Sea sponge Negombata magnifica, have been found to reversibly bind actin monomers, forming a 1:1 complex with G-actin and disrupting its polymerization. The microfilament protein actin is responsible for several essential functions within the cell such as cytokinesis and cell migration. One of the main binding pharmacophores of 1 to G-actin was identified as the C-17 lactol hydroxyl moiety that binds arginine 210 NH. Latrunculin A-17- O-carbamates 2- 6 were prepared by reaction with the corresponding isocyanates. Latrunculin A ( 1) and carbamates 4- 6 displayed potent anti-invasive activity against the human highly metastatic human prostate cancer PC-3M cells in a Matrigel assay at a concentration range of 50 nM to 1 microM. Latrunculin A ( 1, 500 nM) decreased the disaggregation and cell migration of PC-3M-CT+ spheroids by 3-fold. Carbamates 4 and 5 were 2.5- and 5-fold more active than 1, respectively, in this assay with less actin binding affinity. Latrunculin A ( 1, IC 50 6.7 microM) and its 17- O-[ N-(benzyl)carbamate ( 6, IC 50 29 microM) suppress hypoxia-induced HIF-1 activation in T47D breast tumor cells.