Carbamoylphosphonates inhibit autotaxin and metastasis formation in vivo.

Autotaxin is an extracellular, two zinc-centered enzyme that hydrolyzes lysophosphatidyl choline to lysophosphatidic acid, involved in various cancerous processes, e.g. migration, proliferation and tumor progression. We examined the autotaxin inhibitory properties of extended structure carbamoylphosphonates (CPOs) PhOC(6)H(4)SO(2)NH(CH(2))nNHCOPO(3)H(2), with increasing lengths of methylene chains, (CH(2))(n), n = 4-8. Carbamoylphosphonates having n = 6, 7, 8 inhibited autotaxin in vitro with IC(50) ≈ 1.5 µM. Using an imaging probe we demonstrated that compound n = 6 inhibits recombinant autotaxin activity in vitro and in vivo, following oral CPO administration. Additionally, daily oral administration of compound n = 7 inhibited over 90% of lung metastases in a murine melanoma metastasis model. Both the carbamoylphosphonates and the enzymes reside and interact in the extracellular space expecting minimal toxic side effects, and presenting a novel approach for inhibiting tumor proliferation and metastasis dissemination.

Carbamoylphosphonates control tumor cell proliferation and dissemination by simultaneously inhibiting carbonic anhydrase IX and matrix metalloproteinase-2. Toward nontoxic chemotherapy targeting tumor microenvironment.

Carbamoylphosphonates (CPOs) have been identified as inhibitors of matrix metalloproteinases (MMPs) and as orally active, bioavailable, and safe antimetastatic agents. In this article, we focus on the direct antitumor activity of the CPOs. We discovered that CPOs also inhibit carbonic anhydrases (CAs), especially the IX and XII isoforms identified as cancer promoting factors. Thus, CPOs can be regarded as novel nontoxic drug candidates for tumor microenvironment targeted chemotherapy acting by two synergistic mechanisms, namely, inhibiting CAs and MMPs simultaneously. We have also demonstrated that the ionized CPO acid is unable to cross the cell membrane and thus limited to interact with the extracellular domains of isozymes CAIX and CAXII. Finally, applying CPOs against cancer cells in hypoxic conditions resulted in the dose dependent release of lactate dehydrogenase, confirming the direct interaction of the CPOs with the cancer related isozymes CAIX and XII and thereby promoting cellular damage.

Orally active, antimetastatic, nontoxic diphenyl ether-derived carbamoylphosphonate matrix metalloproteinase inhibitors.

Seven 4-phenoxybenzenesulfonamidopolymethylene carbamoylphosphonates (CPOs) bearing two to eight methylene units in the polymethylene chain were synthesized and evaluated as matrix metalloproteinase (MMP) inhibitors. The five lowest homologues [(CH2)2-6] are selective MMP-2 inhibitors, whereas the two with the longest linkers [(CH2)7,8] lack inhibitory activity. The most potent homologues are those with (CH2)5,6; these two were evaluated for antimetastatic activity in a murine melanoma model and showed good potency both by oral and intraperitoneal administration without any toxic--including musculoskeletal--side effects. In contrast to the previously reported cis-ACCP, which was shown to inhibit MMP-2 for ∼30 min, the new compounds inhibit MMP activity for the duration of measurement, lasting several hours. Pharmacokinetic evaluation revealed, on the one hand, low oral bioavailability; on the other hand, a relatively large calculated volume of distribution, consistent with the observed reversible absorption of CPO 5 to hydroxyapatite, as a model for bone.

Aminoalkylcarbamoylphosphonates reduce TNFα release from activated immune cells.

Some carbamoylphosphonates (CPOs) inhibit matrix metalloproteinases (MMPs). Although MMPs are involved in inflammatory processes, the anti-inflammatory activity of CPOs has not been reported. In this context we compared the biological activity of the three aminoCPOs, PYR-CPO, PIP-CPO and cis-ACCP. We were particularly interested in their capability to modulate the secretion of tumor necrosis factor alpha (TNFα). LPS-activated mouse peritoneal macrophages and LPS-activated mouse splenocytes were used to explore this question. It was found that the aminoCPOs were able to reduce TNFα secretion to a level equivalent to the reduction caused by the steroid drug budesonide (BUD). The reduction in TNFα levels was neither accompanied by cytotoxicity, nor did it inhibit cell proliferation. To explicate whether the aminoCPOs affect TNFα processing by TNFα-converting enzyme (TACE), TACE inhibitory properties of the three molecules was tested in vitro. Only PIP-CPO exerted TACE inhibitory activity at therapeutic (non-cytotoxic) concentrations, indicating on its potential to serve as an anti-inflammatory agent by reducing TNFα secretion.

Carbamoylphosphonate matrix metalloproteinase inhibitors 6: cis-2-aminocyclohexylcarbamoylphosphonic acid, a novel orally active antimetastatic matrix metalloproteinase-2 selective inhibitor--synthesis and pharmacodynamic and pharmacokinetic analysis.

cis-2-Aminocyclohexylcarbamoylphosphonic acid ( cis-ACCP) was evaluated in vitro and in two in vivo cancer metastasis models. It reduced metastasis formation in mice by approximately 90% when administered by a repetitive once daily dosing regimen of 50 mg/kg via oral or intraperitoneal routes and was nontoxic up to 500 mg/kg, following intraperitoneal administration daily for two weeks. Pharmacokinetic investigation of cis-ACCP in rats revealed distribution restricted into the extracellular fluid, which is the site of action for the antimetastatic activity and rapid elimination ( t 1/2 approximately 19 min) from blood. Sustained and prolonged absorption ( t 1/2 approximately 126 min) occurred via paracellular mechanism along the small and large intestine with overall bioavailability of 0.3%. The in vivo concentrations of cis-ACCP in the blood in rats was above the minimal concentration for antimetastatic/MMP-inhibitory activity, thus explaining the prolonged action following once daily administration. Finally, 84% of the intravenously administered cis-ACCP to rats was excreted intact in the urine.

Methyltrifluoropyruvate imines possessing N-oxalyl and N-phosphonoformyl groups--precursors to a variety of alpha-CF3-alpha-amino acid derivatives.

Convenient routes to methyl 2-oxalylimino- and 2-(phosphonoformimido)-3,3,3-trifluoropropanoates have been elaborated, based on the reaction of methyl trifluoropyruvate with ethyl oxamate or diethyl carbamoylphosphonate, respectively, followed by dehydration. The compounds obtained are useful synthetic intermediates toward a variety of novel 3,3,3-trifluoroalanine derivatives that are potential drug candidates.

Carbamoylphosphonate matrix metalloproteinase inhibitors 3: in vivo evaluation of cyclopentylcarbamoylphosphonic acid in experimental metastasis and angiogenesis.

The spread of malignant tumor cells from a primary neoplasm to distant organs where they multiply and form new foci is the major cause of death from cancer. Despite the different modalities of cancer treatment, no effective curative therapy of metastatic lesions is available. To possess metastatic potential, a cell has to be able to invade the surrounding tissue, spread via lymphatics and/or the bloodstream, extravasate, and multiply at secondary sites. There is increasing evidence for a positive correlation between matrix metalloproteinase-2 (MMP-2) activity and tumor cell invasion. Agents blocking MMP-2 have been shown to prevent tumor cell invasion in vitro and in vivo. Inhibition of MMPs has, therefore, become the focus of considerable interest in connection with a variety of potential therapeutic applications. We have discovered a nontoxic MMP-2-selective inhibitor effective at nanomolar range on recombinant MMP. This compound, cyclopentylcarbamoylphosphonic acid, significantly inhibited cellular invasion and capillary formation in vitro. Further, i.p. or oral administration of the compound significantly reduced lung metastasis formation and s.c. tumor growth in a murine melanoma model. The effect of this novel compound on lung colonization, capillary formation, and s.c. tumor growth indicates that the compound might also be effective in treatment of primary tumor growth in reduction, or at least in prevention, of further tumor growth, thereby reducing the tumor burden of the patient by a nontoxic approach.

Carbamoylphosphonates, a new class of in vivo active matrix metalloproteinase inhibitors. 1. Alkyl- and cycloalkylcarbamoylphosphonic acids.

Matrix metalloproteinases (MMPs) are a family of over 20 zinc-dependent enzymes that hydrolyze connective tissue and are involved in a variety of diseases, which are associated with undesired tissue breakdown. This paper reports the synthesis, characterization, and biological evaluation of a novel class of MMP inhibitors based on the carbamoylphosphonic acid function. We report a series of 10 open chain N-alkylcarbamoylphosphonic acids (ranging from R = C(1) to C(6) groups), eight N-cycloalkylcarbamoylphosphonic acids (ranging from cyclopropyl to cyclooctyl rings), and four N,N-dialkylcarbamoylphosphonic acids. The compounds were evaluated in three in vitro models, which consisted of (a) the in vitro invasion across a reconstituted basement membrane, (b) determination of the IC(50) values on recombinant MMP-1, MMP-2 MMP-3, MMP-8, and MMP-9 enzymes, and (c) an in vitro capillary formation model, which is a model of angiogenesis. Several of the compounds were also tested in an in vivo murine melanoma model. The following general conclusions have been reached: Most compounds show selectivity for MMP-2 over the other MMP subtypes examined. Cycloalkylcarbamoylphosphonic acids are more potent than comparable open-chain alkyl compounds. Optimal activity against MMP-2 among the cycloalkyl derivatives was shown by N-cyclopentylcarbamoylphosphonic acid (3m). N,N-Dialkylcarbamoylphosphonic acids that were examined showed weak or no activity. The compounds examined showed toxic effects neither in vitro nor in vivo in the concentrations used. Carbamoylphosphonic acids are water soluble at physiological pH and are stable indefinitely.

Carbamoylphosphonate-based matrix metalloproteinase inhibitor metal complexes: solution studies and stability constants. Towards a zinc-selective binding group.

Overactive matrix metalloproteinases (MMPs) are associated with a variety of disease states. Therefore, their inhibition is a highly desirable goal. Yet, more than a decade of worldwide activity has not produced even one clinically useful inhibitor. Because of the crucial role of zinc in the activity of the enzyme, the design of inhibitors is usually based upon a so-called zinc binding group (ZBG). Yet, many of the hitherto synthesized potent inhibitors failed clinically, presumably because they bind stronger to metals other than zinc. We have developed in vivo potent inhibitors based on the carbamoylphosphonic group as a putative ZBG. In this paper we report stability constants for Ca(II), Mg(II), Zn(II) and Cu(II) complexes of two potent, in vivo active, MMP inhibitors, cyclopentylcarbamoylphosphonic acid (1) and 2-( N, N-dimethylamino)ethylcarbamoylphosphonic acid (2). Precipitation prevented the determination of stability constants for iron(III) complexes of1 and2. For comparison with carbamoylphosphonates1 and2, we synthesized 2-cyclohexyl-1,1-difluoroethylphosphonic acid (3), which does not inhibit MMP, and determined the stability constants of its complexes with Mg(II), Ca(II) and Zn(II). Comparison with the values obtained from the complexes of1 and2 with those from3 indicates participation of the C=O group in the metal binding of the former compounds. The complex stability orders for both1 and2 are Ca(II)8 the dimethylamino group of compound2 can also participate in the binding of the transition metals Cu and Zn. On the other hand, the amino group in carbamoylphosphonic acid2 lowers the stability of the complexes with metals favoring oxygen ligands (Ca, Mg and Fe) and increases the selectivity towards Zn. These results are helpful for rationalizing the results observed on our MMP inhibitors hitherto examined, and are expected to be useful for the design of new selective inhibitors.

Synthesis, Characterization, and Crystal Structure of Dicalcium Glutarylbis(phosphonate) Dihydrate: A Covalently Pillared Layer Structure with the Potential for Epitaxial Growth on Hydroxyapatite.

A new bis(acylphosphonate), glutarylbis(phosphonate) (GlBP), was synthesized. Sodium and calcium salts of the GlBP, disodium dihydrogen glutarylbis(phosphonate), NaHO(3)PC(O)(CH(2))(3)C(O)PO(3)HNa, and dicalcium glutarylbis(phosphonate) dihydrate, Ca(2)[O(3)PC(O)(CH(2))(3)C(O)PO(3)].2H(2)O, were prepared and characterized by chemical analyses, thermogravimetry and Fourier transform infrared spectroscopy (FTIR). The crystal structure of the Ca salt was determined by single-crystal X-ray diffraction. The crystals are orthorhombic with a = 10.970(1) Å, b = 23.694(2) Å, c = 5.580(1) Å, space group Pnma, and Z = 4. This study provides the first example of a structure of a calcium complex involving a nongeminal bis(phosphonate). The structure can be described in terms of a covalently pillared layer-type arrangement of neutral Ca-GlBP-Ca units along the b-axis. Each oxygen atom of the phosphonate group is bonded to a different Ca ion, and each Ca in turn is linked to three phosphonate groups. The Ca octahedra and the phosphonate tetrahedra form a two-dimensional polar sheet perpendicular to the b-axis. The chelate bonds involving the keto groups appear to be important links in the stabilization of the structure and, in turn, to the biological activity of bis(acylphosphonates). A near-perfect lattice match, found between the Ca phosphonate layer and the major crystal faces of hydroxyapatite, indicates that epitaxial growth or incorporation of GlBP can occur on the apatitic surface which may be the mode of action in the inhibition of calcification.