Purpose: To estimate the maximum tolerated dose (MTD) for continuous oral administration of the g-secretase inhibitor PF-03084014, determine the recommended phase II dose (RP2D), and evaluate safety and preliminary activity in patients with advanced solid tumors.Experimental Design: This open-label, phase I study consisted of a dose-finding portion based on a 3þ3 design, followed by an expansion cohort. PF-03084014 was administered orally, twice daily (BID) for 21 continuous days. Tested doses ranged from 20 to 330 mg BID. In the expansion cohort, patients were to receive the estimated MTD or a lower dose of PF-03084014.Results: A total of 64 patients received treatment. The MTD was estimated to be 220 mg BID. The RP2D was determined to be 150 mg BID, based on the better safety profile versus the 220-mg BID dose, given comparable NOTCH-related target inhibition. The most common treatment-related adverse events were diarrhea, nausea, fatigue, hypophosphatemia, vomiting, rash, and decreased appetite, which were generally mild to moderate in severity. One patient with advanced thyroid cancer had a complete response, and five of seven response-evaluable patients with desmoid tumor achieved a partial response (71.4% objective response rate). Tumor responses were mostly durable, ranging from 1.74þ to 24þ months. PF-03084014 demonstrated a generally dose-dependent pharmacokinetic profile at doses ranging from 20 to 330 mg BID. Consistent downmodulation of NOTCHrelated HES4 gene expression was observed in peripheral blood from all evaluable patients.Conclusion: Further development of PF-03084014 for the treatment of patients with advanced solid tumors is warranted and currently under evaluation.

Unlike humans and yeast, Plasmodium falciparum, the agent of the most severe form of human malaria, utilizes host serine as a precursor for the synthesis of phosphatidylcholine via a plant-like pathway involving phosphoethanolamine methylation. The monopartite phosphoethanolamine methyltransferase, Pfpmt, plays an important role in the biosynthetic pathway of this major phospholipid by providing the precursor phosphocholine via a three-step S-adenosyl-L-methionine-dependent methylation of phosphoethanolamine. In vitro studies showed that Pfpmt has strong specificity for phosphoethanolamine. However, the in vivo substrate (phosphoethanolamine or phosphatidylethanolamine)is not yet known. We used yeast as a surrogate system to express Pfpmt and provide genetic and biochemical evidence demonstrating the specificity of Pfpmt for phosphoethanolamine in vivo. Wild-type yeast cells, which inherently lack phosphoethanolamine methylation, acquire this activity as a result of expression of Pfpmt. The Pfpmt restores the ability of a yeast mutant pem1⌬pem2⌬ lacking the phosphatidylethanolamine methyltransferase genes to grow in the absence of choline. Lipid analysis of the Pfpmt-complemented pem1⌬pem2⌬ strain demonstrates the synthesis of phosphatidylcholine but not the intermediates of phosphatidylethanolamine transmethylation. Complementation of the pem1⌬pem2⌬ mutant relies on specific methylation of phosphoethanolamine but not phosphatidylethanolamine. Interestingly, a mutation in the yeast choline-phosphate cytidylyltransferase gene abrogates the complementation by Pfpmt thus demonstrating that Pfpmt activity is directly coupled to the Kennedy pathway for the de novo synthesis of phosphatidylcholine.

Background: Human cholesteryl ester transfer protein (CETP) transfers cholesteryl esters from high-density to low-density lipoprotein particles. Results: Crystallographic, mutagenesis, and biochemical studies illuminated inhibition mechanisms of CETP by torcetrapib and a structurally distinct compound, ((2R)-3-{[4-(4-chloro-3-ethylphenoxy)pyrimidin-2-yl][3-(1,1,2,2-tetrafluoroethoxy)benzyl]-amino}-1,1,1-trifluoropropan-2-ol. Conclusion: These small molecules inhibit CETP through blocking its lipid tunnel. Significance: Potential polar interactions at compound binding site may be utilized in design of inhibitors with improved physical properties.

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Background: The high rate of mortality due to malaria and the worldwide distribution of parasite resistance to the commonly used antimalarial drugs chloroquine and pyrimethamine emphasize the urgent need for the development of new antimalarial drugs. An alternative approach to the long and uncertain process of designing and developing new compounds is to identify among the armamentarium of drugs already approved for clinical treatment of various human diseases those that may have strong antimalarial activity.

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Purpose: This study aimed to identify molecular determinants of sensitivity of non-small cell lung cancer (NSCLC) to anti-insulin-like growth factor receptor (IGF-IR) therapy.Experimental Design: A total of 216 tumor samples were investigated, of which 165 consisted of retrospective analyses of banked tissue and an additional 51 were from patients enrolled in a phase II study of figitumumab, a monoclonal antibody against IGF-IR, in stage IIIb/IV NSCLC. Biomarkers assessed included IGF-IR, epidermal growth factor receptor, IGF-II, IGF-IIR, insulin receptor substrate 1 (IRS-1), IRS-2, vimentin, and E-cadherin. Subcellular localization of IRS-1 and phosphorylation levels of mitogenactivated protein kinase and Akt1 were also analyzed.Results: IGF-IR was differentially expressed across histologic subtypes (P = 0.04), with highest levels observed in squamous cell tumors. Elevated IGF-IR expression was also observed in a small number of squamous cell tumors responding to chemotherapy combined with figitumumab (P = 0.008). Because no other biomarker/response interaction was observed using classical histologic subtyping, a molecular approach was undertaken to segment NSCLC into mechanism-based subpopulations. Principal component analysis and unsupervised Bayesian clustering identified three NSCLC subsets that resembled the steps of the epithelial to mesenchymal transition: E-cadherin high/IRS-1 low (epithelial-like), E-cadherin intermediate/IRS-1 high (transitional), and E-cadherin low/IRS-1 low (mesenchymal-like). Several markers of the IGF-IR pathway were overexpressed in the transitional subset. Furthermore, a higher response rate to the combination of chemotherapy and figitumumab was observed in transitional tumors (71%) compared with those in the mesenchymal-like subset (32%; P = 0.03). Only one epithelial-like tumor was identified in the phase II study, suggesting that advanced NSCLC has undergone significant dedifferentiation at diagnosis.Conclusion: NSCLC comprises molecular subsets with differential sensitivity to IGF-IR inhibition.

The PfPMT enzyme of Plasmodium falciparum, the agent of severe human malaria, is a member of a large family of known and predicted phosphoethanolamine methyltransferases (PMTs) recently identified in plants, worms, and protozoa. Functional studies in P. falciparum revealed that PfPMT plays a critical role in the synthesis of phosphatidylcholine via a plantlike pathway involving serine decarboxylation and phosphoethanolamine methylation. Despite their important biological functions, PMT structures have not yet been solved, and nothing is known about which amino acids in these enzymes are critical for catalysis and binding to S-adenosyl-methionine and phosphoethanolamine substrates. Here we have performed a mutational analysis of PfPMT focused on 24 residues within and outside the predicted catalytic motif. The ability of PfPMT to complement the choline auxotrophy of a yeast mutant defective in phospholipid methylation enabled us to characterize the activity of the PfPMT mutants. Mutations in residues Asp-61, Gly-83 and Asp-128 dramatically altered PfPMT activity and its complementation of the yeast mutant. Our analyses identify the importance of these residues in PfPMT activity and set the stage for advanced structural understanding of this class of enzymes.About 41% of the population of the world lives in malaria endemic areas, and every year more than 2 million people die from the disease (1). Malaria is caused by an intraerythrocytic protozoan parasite of the genus Plasmodium. Of the four species that infect humans, Plasmodium falciparum causes the most lethal form of the disease and has developed resistance to almost all the available drugs in the antimalarial armamentarium (2). New chemotherapeutic strategies are now needed to combat this disease. One strategy is to target the metabolic pathways that the parasite uses to synthesize new membranes, which are critical for parasite development and multiplication within erythrocytes (3). Various inhibitors of lipid metabolism have been shown to inhibit P. falciparum proliferation in vitro and in vivo, and several efforts are being made to advance these compounds for treatment of malaria.Phosphatidylcholine (PtdCho) 3 composes half of the phospholipid content of the parasite membranes (4). Biochemical studies demonstrated that PtdCho synthesis occurs via two metabolic routes (5, 6). The first route is the CDP-choline pathway, which uses host choline as a precursor. In this pathway choline is first phosphorylated to phosphocholine and then converted to CDP-choline. Subsequently, CDP-choline and diacylglycerol function as substrates for PtdCho synthesis. The second route is the serine decarboxylation-phosphoethanolamine methylation pathway (6). This pathway uses serine either transported from the host or generated by degradation of host proteins as a phospholipid precursor. The serine is first decarboxylated to produce ethanolamine, by an unknown serine decarboxylase. The ethanolamine is next phosphorylated by a parasite-specific ethanolamine kinase. A SAM-dependent...