EB1627: a soluble prodrug of the potent anticancer cyanoguanidine CHS828.

To overcome pharmacokinetic and solubility problems observed in early clinical trials with the potent anticancer compound CHS828, we synthesised a series of prodrugs with improved properties. The best compound obtained was EB1627, with a tetraethyleneglycol moiety attached to the parent drug via a carbonate linkage. This compound was found soluble enough to be given i.

Synthesis of novel hapten derivatives of 1alpha,25-dihydroxy-vitamin D3 and its 20-epi analogue.

Hapten derivatives of 1alpha,25-dihydroxyvitamin D(3) and its 20-epimer were synthesized and conjugated to a carrier protein for raising polyclonal antibodies. The haptens were linked through spacers at C-16, thereby exposing both the A-ring and the side chain of the molecules, to maximize antibody specificity. The spacers were introduced via stereoselective hydroboration of 16-ene intermediates as the key step.

The synthesis of [26,27-11C]dihydroxyvitamin D(3), a tracer for positron emission tomography (PET).

1Alpha,25-dihydroxyvitamin D(3), an endogenous ligand with the highest affinity for the vitamin D receptor (VDR), was labeled with 11C for use in biological experiments. The radionuclide was incorporated via the reaction of [11C]methyllithium on a methyl ketone precursor in tetrahydrofuran at -10 degrees C. Deprotection of the labeled intermediate yielded 2.

Polyclonal antibodies to EB1089 (seocalcitol), an analog of 1alpha,25-dihydroxyvitamin D(3)*.

A hapten derivative of EB1089 [1(R),3(S),25-trihydroxy-26,27-dimethyl-9,10-seco-24-homocholesta-5(Z),7(E),10(19),22(E),24(E)-pentaene], a side-chain analog of 1alpha,25-dihydroxyvitamin D(3), was synthesized for raising antibodies with a high specificity for EB1089. The A-ring moiety of EB1089 was replaced in the hapten by a linker for conjugation to a protein. Three polyclonal antibodies were obtained by immunizing rabbits with a BSA-conjugate of the hapten.

Examination of structurally selective derivatization of vitamin D(3) analogues by electrospray mass spectrometry.

The structural specificity of vitamin D derivatization by PTAD (4-phenyl-1,2,4-triazoline-3,5-dione) was probed using synthetic analogues and ion trap mass spectrometry. EB 1089, a vitamin D(3) analogue which contains a second site for Diels--Alder cycloaddition on its side-chain, allowed the examination of derivatization modes and comparisons of ion fragment structures. The origins of a PTAD-vitamin D(3) ion fragment, commonly used in metabolite characterization and quantitation of vitamin D(3) analogues (m/z 314), were established; ion trap mass spectrometry revealed that the PTAD comprises a portion of this diagnostic fragment, and is not lost by a retro-Diels--Alder step.

Seocalcitol (EB 1089): a vitamin D analogue of anti-cancer potential. Background, design, synthesis, pre-clinical and clinical evaluation.

It is well established that the metabolically active form of vitamin D, 1alpha,25-dihydroxyvitamin D3 (1alpha,25(OH)2D3) plays a key role in the establishment and maintenance of the calcium metabolism in the body. In addition to this classic effect of 1alpha,25(OH)2D3, substantial evidence has emerged demonstrating that 1alpha,25(OH)2D3 is able to regulate cell growth and differentiation in a number of different cell types, including cancer cells. However, the clinical usefulness of 1alpha,25(OH)2D3 is limited by its tendency to cause hypercalcaemia.

Determination of the vitamin D analog EB 1089 (seocalcitol) in human and pig serum using liquid chromatography-tandem mass spectrometry.

A liquid chromatographic-tandem mass spectrometric assay in human and pig serum has been developed for quantitative analysis of EB 1089 (seocalcitol). EB 1089 is a novel vitamin D analog under development for the treatment of cancer. The analyte was extracted from serum after protein precipitation using an automated solid-phase extraction procedure involving both a reversed-phase and normal-phase procedure on a single C18 cartridge.

Metabolism of the vitamin D3 analogue EB1089 alters receptor complex formation and reduces promoter selectivity.

1. 1alpha,25-dihydroxyvitamin3 (VD) is a nuclear hormone that has important cell regulatory functions but also a strong calcemic effect. EB1089 is a potent antiproliferative VD analogue, which has a modified side chain resulting in increased metabolic stability and a selective functional profile.

Structural variants of the vitamin D analogue EB1089 reduce its ligand sensitivity and promoter selectivity.

The nuclear hormone 1alpha,25-dihydroxyvitamin D3 (VD) has important cell-regulatory functions but also a strong calcemic effect. Therefore, various VD analogues have been synthesized and screened for their biological profile. In order to gain more insight into the molecular basis of the high antiproliferative but low calcemic action of the VD analogue EB1089, we characterized this compound in comparison to five structurally related VD analogues.

The vitamin D analog, KH1060, is rapidly degraded both in vivo and in vitro via several pathways: principal metabolites generated retain significant biological activity.

Vitamin D analogs are valuable drugs with established and potential uses in hyperproliferative disorders. Lexacalcitol (KH1060) is over 100 times more active than 1alpha,25-dihydroxyvitamin D3 [1alpha,25-(OH)2D3], as judged by in vitro antiproliferative and cell differentiating assays. The underlying biochemical reasons for the increased biological activity of KH1060 are unknown, but are thought to include 1) metabolic considerations in addition to explanations based upon 2) enhanced stability of KH1060-liganded transcriptional complexes.

Metabolism of the vitamin D analog EB 1089: identification of in vivo and in vitro liver metabolites and their biological activities.

1(S),3(R)-dihydroxy-20(R)-(5'-ethyl-5'-hydroxy-hepta-1'(E),3'(E)-dien -1'-yl)-9,10-secopregna-5(Z),7(E),10(19)-triene (EB 1089) is a novel analog of the vitamin D hormone, calcitriol that has been modified in the side-chain resulting in an increased metabolic stability relative to other side-chain modified analogs (e.g. calcipotriol and 22-oxacalcitriol).

Metabolism of the vitamin D analog EB1089 by cultured human cells: redirection of hydroxylation site to distal carbons of the side-chain.

1(S),3(R)-dihydroxy-20(R)-(5'-ethyl-5'-hydroxy-hepta-1'(E),3' (E)-dien-1'-yl)-9,10-secopregna-5(Z),7(E),10(19)-triene (EB1089) is a novel synthetic analog of 1 alpha,25-dihydroxyvitamin D [1,25-(OH)2D3] with potential for use in the treatment of hyperproliferative disorders. It has an altered side-chain structure compared to 1,25-(OH)2D3, featuring 26,27 dimethyl groups, insertion of an extra carbon atom (24a) at C-24, and two double bonds at C-22,23 and C-24,24a. In vitro metabolism of EB1089 was studied in a human keratinocyte cell model, HPK1A-ras, previously shown to metabolize 1,25-(OH)2D3.

Disodium 1-hydroxy-3-(1-pyrrolidinyl)-propylidene-1,1-bisphosphonate (EB-1053) is a potent inhibitor of bone resorption in vitro and in vivo.

The ability of the new nitrogen-containing bisphosphonate disodium-1-hydroxy-3-(1-pyrrolidinyl)-propylidene-1,1-bisphosphona te (EB-1053) to inhibit osteoclastic resorption was examined in vitro and in vivo. Results were compared to those obtained with 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (pamidronate or APD). In vitro, when tested in osteoclast precursor-dependent systems (fetal mouse metacarpals and a coculture system), EB-1053 suppressed 45Ca release effectively and was found to be about 10 times more potent than pamidronate (ED50 = 2.

20-epi-vitamin D3 analogues: a novel class of potent regulators of cell growth and immune responses.

The 20-epi-vitamin D3 analogues are a novel class of vitamin D3 derivatives, structurally related to 1 alpha,25-dihydroxycholecalciferol (1 alpha,25(OH)2D3). They are characterized by an altered stereochemistry at carbon 20 in the side-chain. In vitro, these new analogues were found to be considerably more potent as regulators of growth and differentiation in the human histiocytic lymphoma cell line U 937 than 1 alpha,25(OH)2D3, despite a practically unchanged calcemic activity in vivo.

Mutual pro-drugs of beta-lactam antibiotics and beta-lactamase inhibitors.

The principle of combining a beta-lactam antibiotic with a beta-lactamase inhibitor in a single molecule functioning as pro-drug for the two active components is illustrated by the linked esters 3 and 4 in which ampicillin and mecillinam, respectively, are combined with the beta-lactamase inhibitor penicillanic acid sulfone. It is shown that in man these esters are excellently absorbed from the gastro-intestinal tract and after absorption hydrolyzed with simultaneous liberation of the active components. As a result high blood and tissue levels of antibiotic and beta-lactamase inhibitor in a balanced ratio are attained.

1alpha-hydroxycholecalciferol. Long-term treatment of patients with uraemic osteodystrophy.

Three adolescents with uraemic osteodystrophy were treated for 7 months with daily oral doses of 1alpha-hydroxycholecalciferol (0.25-10.0 mug).

Long-term treatment of uraemic osteodystrophy with 1-alpha-hydroxycholecalciferol.

Three adolescents on regular haemodialysis were treated for more than one year with 1alphaOHD3 in doses of 0.25 - 10 mug/day orally. All the patients had hypocalcaemia, a high serum level of alkaline phosphatase and signs of uraemic osteodystrophy on X-ray.