MX-100 (also known as PL-100) is a benzenesulfonamide derivative patented by Pharmacor Inc as HIV aspartyl protease inhibitor. MX-100 retained excellent antiviral activity against almost all of these protease inhibitor-resistant viruses and that its performance in this regard was superior to those of atazanavir, amprenavir, indinavir, lopinavir, nelfinavir, and saquinavir. In almost every case, the increase in the EC50 for MX-100 observed with viruses containing multiple mutations in protease was far less than that obtained with the other drugs. Preclinical studies showed that MX-100 possessed suboptimal solubility and pharmacokinetic, (PK) properties, possibly hindering further development. MX-100 successfully completed preclinical and clinical development (phase I in healthy volunteers) and have been licensed to Merck in 2006

CRS-3123, also known as REP-3123, is a methionyl-tRNA synthetase inhibitor potentially for the treatment of enteric infections. CRS-3123 is in Phase 1 clinical development for the treatment of Clostridium difficile Infection (CDI). CRS-3123 is a small molecule protein synthesis inhibitor that acts on the novel target methionyl-tRNA synthetase (MetRS). REP-3123 has been shown to be active in vitro against clinical isolates of C. difficile including epidemic strains such as B1/ NAP1/027; MIC values of REP-3123 for C. difficile are typically 0.5 -- 1.0 mg/l. REP-3123 is also active against a range of clinically important aerobic Gram-positive bacteria including methicillin-susceptible and -resistant Staphylococcus aureus (MIC90 values of 0.06 and 0.25 mg/l, respectively), Streptococcus pyogenes (MIC90 0.5 mg/l) and enterococci (MIC90 32 mg/l). CRS-3123 has numerous potential advantages over current CDI therapies. In addition to being highly potent against all clinical isolates of C. difficile tested, CRS-3123 has several desirable qualities for the treatment of CDI which include: Narrow spectrum for C. difficile, which may substantially reduce the disruption of normal intestinal flora compared to current therapies; Inhibition of toxin production, potentially leading to lower morbidity and mortality; Inhibition of sporulation, potentially leading to lower rates of transmission and recurrence; A novel mechanism of action, which means that its use will not compromise the utility of systemic antibiotics while maintaining activity against pre-existing resistance mechanisms.

PTX-008 (OTX008) is a calixarene-based compound and galectin-1 (Gal-1) inhibitor with potential anti-angiogenic and antineoplastic activities. Upon subcutaneous administration, galectin-1 inhibitor OTX008 binds Gal-1 which leads to Gal-1 oxidation and proteosomal degradation through a not yet fully elucidated mechanism, and eventually downregulates Gal-1. This decreases tumor cell growth and inhibits angiogenesis. Gal-1, a multifunctional carbohydrate-binding protein, is often overexpressed on tumor cells and plays a key role in cancer cell proliferation, apoptosis, tumor angiogenesis and evasion of immune responses. PTX-008 had been in phase I clinical trials for the treatment of solid tumours. This compound was originally discovered by University of Minnesota and PepTx, then licensed to OncoEthix (acquired by Merck Sharp & Dohme in 2014). However, no recent developments has been reported.

NCX-4016, a nitric oxide non-steroidal anti-inflammatory drug (NO-NSAID) which can inhibit cyclooxygenase as well as release nitric oxide, is under development by NicOx as a potential treatment for thrombosis, inflammation and rheumatoid arthritis. NCX-4016 possesses a broad spectrum of antithrombotic and antiinflammatory activities. NCX-4016 has been shown to inhibit platelet activation in vitro more effectively than aspirin, to inhibit smooth muscle cell proliferation, to exert an endothelial cell protective activity and to suppress the function of several inflammatory cells potentially involved in atherothrombosis. In animal models, NCX-4016 protected from platelet thromboembolism, prevented restenosis in atherosclerosis-prone animals, protected the heart from ischemia/reperfusion injury, and induced neoangiogenesis in critically ischemic limbs. Moreover, it displayed little or no gastric toxicity and appeared to protect stomach from noxious stimuli, including aspirin. NCX-4016 has been evaluated in healthy volunteers and found to inhibit platelet cyclo-oxygenase-1 (COX-1) similarly to or slightly less than aspirin, to raise the circulating levels of NO-degradation products, and to have little or no gastric toxicity in short term studies. NCX-4016 was in Phase II clinical trials for the treatment of vascular disorders such as peripheral vascular disease and other cardiovascular diseases including thrombosis, complications of endothelium-related diseases such as diabetes and other. But this research was discontinued.