Marizomib is a natural beta-lactone produced by the marine bacterium Salinispora tropica. Marizomib has a broad inhibition profile for the 20S proteasome and has been shown to inhibit the CT-L (beta5) CT-T-laspase-like (C-L, beta1) and trypsin-like (T-L, beta2) activities of the 20S proteasome. The drug is being tested in phase II clinical trials for the treatment of Multiple Myeloma and Malignant Glioma and in phase I in patients with Non-small Cell Lung Cancer, Pancreatic Cancer, Melanoma or Lymphoma

3,5-Diiodothyropropionic acid (DITPA), a carboxylic acid analog with low metabolic activity, was observed to induce alpha-MHC mRNA in heart cell culture with EC50 approximately 5 x 10(-7) M. Zarion Pharmaceuticals was developing DITPA (3,5-diiodothyropropionic acid), a thyroid hormone analogue, for the treatment of Allan-Herndon-Dudley syndrome. In May 2013, the US FDA granted DITPA orphan drug status for the treatment of Allan-Herndon-Dudley syndrome. However, development of DITPA for the treatment of Allan-Herndon-Dudley syndrome was discontinued.

Ecopipam (SCH-39166) is a selective D1 dopamine receptor antagonist both in vitro and in vivo. Additionally, it exhibits saturable, high-affinity binding to D5 receptors. Ecopipam was studied clinically for a variety of indications, including schizophrenia, drug abuse, and obesity, but in each case undesirable effects were observed. Currently, ecopipam is in clinical trials for the treatment of Lesch-Nyhan and Gilles de la Tourette's syndromes.

AR-42, also known as (S)-HDAC-42, is a phenylbutyrate-based histone deacetylase (HDAC) inhibitor. HDACs are enzymes that determine acetylation status of histones, thereby affecting chromatin structure and regulating the expression and activity of numerous proteins involved in both cancer initiation and cancer progression. AR-42 possesses antitumor activity at multiple cellular levels. It is currently in Phase I/Ib trials for hematological malignancies and solid tumors.

Picropodophyllin (also known as picropodophyllotoxin (PPP)), an orally active insulin-like growth factor 1 receptor (IGF1R) inhibitor that exhibits no activity at the insulin receptor, FGFR, PDGFR or EGFR. Picropodophyllin possesses antineoplastic activity. PPP is currently tested as an orally administrated single agent treatment in an open-label combined Phase I/II clinical study in advanced cancer patients with solid tumors which progress in spite of several lines of treatment. In addition, it effectively inhibits rhambodmyosarcomas tumor proliferation and metastasis in vitro and in an animal model.

Tempol is used as an industrial catalyst and chemical oxidant. However, its ability to scavenge free oxygen species has generated interest in the biochemical potential of this compound. Biologically Tempol catalyzes the disproportionation of superoxides, facilitates hydrogen peroxide metabolism, and inhibits Fenton chemistry. These properties generated investigational interest for the use of tempol to mediate radiation damage during chemotherapy. Tempol has been used in human clinical trials for mitigation of radiation damage in related to anal cancer, and brain cancer. Tempol has also been investigated in a number of animal and invitro models for conditions, such as oxidative damage, brain hemorrhage, anxiety, malaria, platelet agregation,

Tetrahydrouridine is a potent competitive reversible inhibitor of cytidine deaminase. Tetrahydrouridine can inhibit cell proliferation by regulation of the cell cycle independent of cytidine deaminase (CDA) expression levels. Tetrahydrouridine may be useful for researching potential treatments for high CDA-expressing tumors. Tetrahydrouridine use, alone or in combination with the DNA methyltransferase inhibitor 5-fluoro-2’-deoxycytidine, is being evaluated in animal models and clinical trials for diseases, including cancer and mitochondrial DNA depletion syndrome.