Almurtide (CGP 11637) is a synthetic muramyl dipeptide (MDP) analogue with potential immunostimulating and antineoplastic activity. As a derivative of the mycobacterial cell wall component MDP, almurtide activates both monocytes and macrophages. This results in the secretion of cytokines and induces the recruitment and activation of other immune cells, which may result in indirect tumoricidal or cytostatic effects. CGP 11637 has been shown to prevent oncogenic viral infections in mice.

Arbaclofen (STX209, R-baclofen), a selective agonist of GABA-B receptors, has been investigated in clinical trials for the treatment of autism spectrum disorder ASD, phase II and for the treatment of patients with fragile X syndrome in phase III. As a result, the drug did not meet the primary outcome of improved social avoidance in FXS in either study. In spite of positive results in some children with ASD, further study will be needed to replicate and extend these initial findings. Arbaclofen has also been investigated in phase III clinical trials as a treatment for spasticity due to multiple sclerosis.

Sulfachrysoidine is a sulfamylchrysoidine derivative and lipid-soluble azo dye with antibacterial activity.

Folitixorin, a thymidylate synthase inhibitor is a substrate used by the enzyme methylenetetrahydrofolate reductase (MTHFR) to generate 5-methyltetrahydrofolate. Folitixorin was studied in clinical trials for the treatment of breast cancer, metastatic colorectal cancer and for the treatment of advanced pancreatic cancer. Folitixorin had been granted orphan drug status for the treatment of pancreatic cancer in both the U.S. and EU. However, further development of this drug was discontinued.

Clantifen is an aminothiophene derivative invented by Hoersht AG. The compound is claimed to have antiphlogistic and antipyretic properties.

Sinefungin, a natural nucleoside isolated from cultures of Streptomyces incarnatus and S. griseolus, is structurally related to S-adenosylhomocysteine and S-adenosylmethionine. Sinefungin is a DNA methyltransferase (DNMT) inhibitor (IC₅₀ = 0.1 - 20 uM). Sinefungin has been shown to inhibit the development of various fungi and viruses, but its major attraction to date resides in its potent antiparasitic activity. This compound has been reported to display antiparasitic activity against malarial, trypanosomal, and leishmanial species. Sinefungin inhibits pneumococcal biofilm growth in vitro and colonization in vivo, decreases AI-2 production, and downregulates luxS, pfs, and speE gene expressions. Sinefungin was significantly suppressive against both L. donovani and L. braziliensis panamensis infections in hamsters when compared with meglumine antimonate. An immunosuppressed rat model was used to investigate the anti-Cryptosporidium parvum activity of sinefungin. In infected animals, oral sinefungin therapy resulted in a dose-related suppression of oocyst shedding, which correlated with oocyst disappearance from ileal sections. When administered prior to or on the day of oocyst challenge, sinefungin successfully prevented infection. These data suggest that sinefungin could be considered as a candidate molecule in the treatment of human cryptosporidiosis, considered to be the most significant enteric opportunistic infection in AIDS.

2-Cyano-3,12-dioxooleana-1,9-diene-28-oic acid (CDDO, also known as Bardoxolone) is a synthetic triterpenoid that displays potent anti-inflammatory and antitumorigenic activities. CDDO was in the clinical trial phase I for the treatment patients with Solid tumors and leukemia, but that studies were discontinued. It is known, that CDDO blocks the cellular synthesis of inducible nitric oxide synthase and inducible COX-2. In addition, was discovered, that CDDO disrupted intracellular redox balance and thereby induce apoptosis. Moreover, CDDO is a ligand for peroxisome proliferator-activated receptor that it induces genes regulated by Nrf2, including heme oxygenase-1 and eotaxin-1, which play a role in antioxidant response element signaling activity.

Ciluprevir (BILN-2061) is a selective inhibitor of the HCV NS3 serine protease, which was developed by Boehringer Ingelheim for the treatment of hepatitis C infection. The drug was discontinued in phase II due to adverse events such as cardiac toxicity (demonstrated in animals). In the cell-based replicon assay, ciluprevir inhibited HCV RNA replication at low nanomolar levels. It had inhibitory rate constant (Ki) values of 0.3 and 0.66 nM for the NS3 proteases of HCV genotypes 1a and -1b, respectively.

Metethoheptazine (WY-535) is an analgesic agent.

BMS-908662 (previously known as XL281) is a small molecule Raf kinase inhibitor that lies immediately downstream of RAS and are key components of the RAS/RAF/MEK/ERK kinase-signaling pathway. Bristol-Myers Squibb has received an exclusive worldwide license to develop and commercialize antineoplastic agent XL281. BMS-908662 participated in phase I development for the treatment of patients with melanoma and in combination with cetuximab for patients with colorectal cancer. However, further, development has been discontinued.