Ezatiostat (TLK199) [γ-glutamyl-S-(benzyl)cysteinyl-R-phenyl glycine diethyl ester] is an inhibitor of Glutathione S-transferase P1–1 (GSTπ). The drug is a peptidomimetic of GSH (glutathione), esterified to enhance cellular uptake and designed to bind to the “G-site” of GSTP1–1. Independent of catalysis inhibition, TLK199 also disrupts the protein:protein interaction site(s) between GSTP1–1 and JNK1. Telik Inc was developing TLK-199 for the potential prevention of myelosuppression in blood diseases, namely myelodysplastic syndrome.

Droxacin is quinolone antibiotic. It is topoisomerase inhibitor.

Abexinostat (PCI-24781) is a novel, second-generation phenyl hydroxamic acid–based, orally bioavailable HDAC inhibitor that has previously been shown to have activity in vitro and in vivo against a broad array of cancers, including hematopoietic malignancies and bone and soft-tissue sarcomas. Abexinostat is a pan-HDAC inhibitor mostly targeting HDAC1 with Ki of 7 nM, modest potent to HDACs 2, 3, 6, and 10 and greater than 40-fold selectivity against HDAC8. Abexinostat exhibits potent antitumor activity against a variety of tumor cell lines with GI50 ranging from 0.15 uM to 3.09 uM. PCI-24781 also has an antiproliferative effect on HUVEC endothelial cells with GI50 of 0.43 uM. Abexinostat treatment causes dose-dependent accumulation of both acetylated histones and acetylated tubulin in HCT116 or DLD-1 cells, induces expression of p21, and leads to PARP cleavage and accumulation of the γH2AX. It has also shown good tolerability and activity in Phase I and II clinical trials against lymphoma, as well as against solid tumors in Phase-I trials. Additionally, it acts as a potent radiosensitizing agent and is synergistic with cytotoxic chemotherapy, such as doxorubicin in preclinical models.

Adaprolol is a beta-adrenergic antagonist that is being developed as a topical agent to treat glaucoma. Adaprolol demonstrated a safer cardiovascular profile, especially in the population over 70 years old. It was in Phase II clinical trials for the treatment of glaucoma. This research has been discontinued.

Xenbucin is an antihyperlipidemic agent. Information about the current use of this agent is not available.

Declopramide is an apoptosis inducer. Also, it inhibits NFkappaB activation by inhibition of IkappaBbeta breakdown. In preclinical research, Declopramide demonstrated strong antitumor properties. It had been in phase II clinical trials for the treatment of colorectal cancer. However, this research has been discontinued.

Imiloxan is a highly selective alpha2B adrenoceptor antagonist and was developed for depression in the 1980s. In Phase 1 clinical trials imiloxan dosing led to hypersensitivity reactions; the molecule's development was discontinued.

Canfosfamide is a modified glutathione analogue and nitrogen mustard prodrug, with potential antineoplastic activity. Canfosfamide is selectively activated by glutathione S-transferase P1-1 an enzyme that is over-expressed in many human cancers including ovarian cancer. GST P1-1-mediated cleavage leads to an active cytotoxic phosphorodiamidate alkylating metabolite that forms covalent linkages with nucleophilic centers in tumor cell DNA, which may induce a cellular stress response and cytotoxicity, and decrease tumor cell proliferation. Preclinical studies showed that canfosfamide inhibited the growth and was cytotoxic to a wide range of established cancer cell lines including those derived from ovarian cancer (OVCAR3, HEY, SK-OV-3). Canfosfamide treatment inhibited cancer cell proliferation and induced apoptosis through the activation of the cellular stress response kinase pathway. The cytotoxic activity of canfosfamide correlated with the expression of GST P1-1. Cancer cells in which GST expression levels were increased by transfection with the GST P1-1 gene, were more sensitive to the cytotoxic effects of canfosfamide than the parental cell lines Canfosfamide in combination with pegylated liposomal doxorubicin is well tolerated and active in platinum and paclitaxel refractory or resistant ovarian cancer.

Ezatiostat (TLK199) [γ-glutamyl-S-(benzyl)cysteinyl-R-phenyl glycine diethyl ester] is an inhibitor of Glutathione S-transferase P1–1 (GSTπ). The drug is a peptidomimetic of GSH (glutathione), esterified to enhance cellular uptake and designed to bind to the “G-site” of GSTP1–1. Independent of catalysis inhibition, TLK199 also disrupts the protein:protein interaction site(s) between GSTP1–1 and JNK1. Telik Inc was developing TLK-199 for the potential prevention of myelosuppression in blood diseases, namely myelodysplastic syndrome.

Varespladib (LY315920; A-001) is a potent and selective inhibitor of IIa, V, and X isoforms of human non-pancreatic secretory phospholipase A2 with nM IC50. The molecule acts as an anti-inflammatory agent by disrupting the first step of the arachidonic acid pathway of inflammation. Varespladib methyl is being developed by Anthera Pharmaceuticals Inc for the potential treatment of coronary artery disease, acute coronary syndrome and inflammation. Varespladib methyl is a prodrug that is rapidly metabolized to varespladib, and both compounds are able to potently inhibit the enzymes of the human secretory phospholipase groups. Phase II clinical trials of varespladib methyl in patients with coronary artery disease, rheumatoid arthritis, asthma and ulcerative colitis revealed that the drug was well tolerated. Varespladib methyl did not demonstrate a good efficacy profile in patients with rheumatoid arthritis, asthma and ulcerative colitis; whereas in patients with coronary artery disease, varespladib methyl consistently reduced LDL-cholesterol levels, (elevated LDL-cholesterol levels are a marker of increased cardiovascular risk). Varespladib methyl could represent a novel therapy for the treatment of cardiovascular disease, although the efficacy, safety profile and advantages of this drug compared with existing therapeutic options would need to be established in upcoming phase III trials.