British Biotech was developing solimastat [BB 3644], an inhibitor of tumour necrosis factor and matrix metalloproteinase, as a potential treatment for colorectal cancer, inflammatory bowel diseases and rheumatoid arthritis. BB-3644 is an oral, broad-spectrum matrix metalloproteinase inhibitor (MMPI) structurally related to marimastat and BB-94. It is also >10-fold more active than marimastat in inhibiting the processing of cell-bound TNF-alpha. Solimastat development has been discontinued due to significant musculoskeletal toxicity.

TNP-470 (AGM-1470, (3R,4S,5S,6R)-5-methoxy-4- [(2R,3R)-2-methyl-3-(3-methyl-2-butenyl) -oxiranyl]-1-oxaspiro[2,5]oct-6-yl(chloroacetyl) carbamate) is an anti-angiogenic, semisynthetic analogue of fumagillin, a known antibiotic secreted by the fungus Aspergillus fumigatus fresenius, which is under clinical development for the treatment of cancer by Takeda Chemical Industries Ltd. in Japan and TAP Pharmaceuticals, Inc. in the United States. TNP-470 binds to and irreversibly inactivates methionine aminopeptidase-2 (MetAP2), resulting in endothelial cell cycle arrest late in the G1 phase and inhibition of tumor angiogenesis. This agent may also induce the p53 pathway, thereby stimulating the production of cyclin-dependent kinase inhibitor p21 and inhibiting angiogenesis. In early clinical reports, TNP-470 is tolerated up to 177 mg/m(2) with neurotoxic effects (fatigue, vertigo, ataxia, and loss of concentration) being the principal dose-limiting toxicity (DLT). TNP-470 is being evaluated in Phase I-II trials in the US in patients with Kaposi’s sarcoma, cervical cancer, breast cancer, brain cancer, prostate cancer and renal cell carcinoma.

Apratastat (Tmi 005) was developed by Wyeth Research as a dual TNF-alpha-converting enzyme and matrix metalloprotease-13 inhibitor for the treatment of rheumatoid arthritis. Apratastat was in phase II clinical trials, but because of the lack of efficacy, this trial was terminated.

Valategrast (R-411) is a dual-acting α4/β1 - α4/β7 integrin antagonist which underwent clinical development with Roche for the treatment of multiple sclerosis (MS) and asthma. Phase I and II studies have been conducted. It had shown good efficacy in animal disease models. Following oral administration, R-411 was rapidly and completely biotransformed into its active metabolite, RO-0270608, most of which was eliminated by biliary excretion. R-411 had shown acceptable pharmacokinetics and good safety in healthy volunteers. R-411 inhibited eosinophil and T H 2 cell excitation and survival, and inhibited eosinophil migration from blood to pulmonary tissues. The idea of combining R-411 with montelukast (leukotriene antagonist) in the pharmaceutical dosage forms, therefore, provided a therapeutic treatment that had the combined effect of reducing circulating eosinophil counts and reducing eosinophil egress into pulmonary tissues, thereby providing an early onset of bronchodilation as well as sustained anti-inflammatory effects. Valategrast had been in phase II clinical trials by Roche for the treatment of asthma and in phase I clinical trials for the treatment of multiple sclerosis (MS). However, the study had been discontinued. Development of Valategrast was discontinued for the treatment of asthma after clarification of the regulatory framework for that class of compounds.

Halofuginone is a low molecular weight quinazolinone alkaloid, and a potent inhibitor of collagen alpha1(I) and matrix metalloproteinase 2 (MMP-2) gene expression. Halofuginone also effectively suppresses tumor progression and metastasis in mice. Halofuginone is a potent inhibitor of collagen a1(I) and matrix metalloproteinase 2 (MMP-2) gene expression. Halofuginone also suppresses extracellular matrix deposition and cell proliferation. Also was shown that halofuginone increased apoptosis in α smooth muscle actin- and prolyl 4-hydroxylase β-expressing cells in mdx diaphragm and in myofibroblasts, the major source of extracellular matrix. The profound antitumoral effect of halofuginone is attributed to its combined inhibition of tumour-stromal support, vascularization, invasiveness, and cell proliferation. HT-100 (delayed-release halofuginone), currently in clinical phase 1b/2a in five U.S. hospitals, is a small molecule drug candidate taken orally for the treatment of Duchenne muscular dystrophy (DMD) patients primarily through its ability to reduce fibrosis and inflammation and promote muscle fiber regeneration. The medicine candidate has been granted orphan drug designation in the U.S. and the EU — meaning it has been commercially undeveloped due to its limited profitability — and fast-track designation in the U.S. — an FDA process that aims to facilitate the development and patients’ reach to novel therapies for unmet medical needs.

Cipemastat (Ro 32-3555, tentative trade name Trocade) is a dipeptide, potent, competitive inhibitor of matrix metalloproteinases (MMP) 1, 8 and 13, which was under development by Roche for the potential treatment of rheumatoid arthritis. Cipemastat is a selective inhibitor of metalloproteinases 1, 8 and 13 over the related human matrix metalloproteinases stromelysin 1, and gelatinases A and B. Cipemastat mediated MMP inhibition leads to block the final common event in the destructive cascade resulting in the breakdown of cartilage and bone. Trocade has also been shown to inhibit cartilage destruction in vivo and to prevent structural joint damage in animal models of rheumatoid and osteoarthritis. Cipemastat was in phase II clinical trials for the treatment of rheumatoid arthritis. However, Roche discontinued the development of cipemastat because of an unfavorable risk-benefit profile.

Marimastat is a broad spectrum matrix metalloprotease (MMP) inhibitor. It is an angiogenesis and metastasis inhibitor. It mimics the peptide structure of natural MMP substrates and binds to matrix metalloproteases, thereby preventing the degradation of the basement membrane by these proteases. This antiprotease action prevents the migration of endothelial cells needed to form new blood vessels. Inhibition of MMPs also prevents the entry and exit of tumor cells into existing blood cells, thereby preventing metastasis. Marimastat has been in pivotal phase III trials in glioblastoma, breast, ovarian and small and non-small cell lung cancer, but these trials have all been discontinued because marimastat failed to show superior efficacy over either standard chemotherapy or placebo.

Nafoxidine is a nonsteroidal antiestrogen available as an investigational agent from the Investigational Drug Branch of the National Cancer Institute. It has been used effectively in the treatment of breast cancer patients. Nafoxidine competes with endogenous estrogen for binding to specific estrogen receptors. This agent also inhibits angiogenesis in some tissues by blocking the effects of fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF); paradoxically, it may enhance angiogenesis in uterine tissue. Nafoxidine also induces oxidative stress, protein kinase C and calcium signaling.

PPI-2458 is a synthetic derivative of fumagillin with antineoplastic and cytotoxic properties. PPI-2458 irreversibly inhibits the enzyme methionine aminopeptidase type 2 (MetAP2), thereby preventing abnormal cell growth and angiogenesis. PPI-2458 is reported to have a better toxicity profile compared to other agents of its class. In a phase 1 clinical study, PPI-2458 was administered to patients with non-Hodgkin lymphoma. The data confirm the participation of active metabolites in the in vivo efficacy of PPI-2458. In in vitro studies, osteoclast formation and activity were inhibited by PPI-2458, a mechanism not previously attributed to MetAP-2 inhibition. PPI-2458 treatment reduced synovial and osteochondral angiogenesis, synovial inflammation, joint damage, and pain behavior. PPI-2458 exerts disease-modifying activity in experimental arthritis through its direct inhibition of several pathophysiologic processes of this disease. These results provide a rationale for assessing the potential of PPI-2458 as a novel rheumatoid arthritis therapy.