Amelubant, its metabolite BIIL 260 (formed by removal of the ethoxycarbonyl protecting group), and its major metabolite BIIL 315 (formed by removal of the protecting group and glucuronidation) had potent in vitro and in vivo Leukotriene B4 receptor antagonistic properties. Amelubant has been in phase II clinical trials by Boehringer Ingelheim for the treatment of cystic fibrosis, chronic obstructive pulmonay disease, bronchial asthma and rheumatoid arthritis. However, this research has been discontinued. In 2002, orphan drug designation was received in E.U. for the treatment of cystic fibrosis. Serious adverse events of Amelubant were characterized by increased presentation of respiratory signs and/or symptoms associated with pulmonary exacerbation and resulted in admission to a hospital and/or administration of IV antibiotics.

Amsilarotene (TAC-101) is a retinobenzoic acid (RAR) derivative with high affinity to the RAR-alpha receptor. It is a Retinoic acid receptor alpha antagonist. Amsilarotene is an orally absorbed synthetic retinoid. This analogue of vitamin A (retinol) binds to nuclear retinoic acid receptor-a (RAR-a), activates RAR-a transcriptional activity, and has shown antitumor activity in primary and metastatic preclinical models of liver cancer. Amsilarotene inhibits retinoblastoma-gene product (RB) phosphorylation and increases the presence of 2 cyclin-dependent kinase (CDK) inhibitors, resulting in cell cycle arrest. This agent also causes a cytotoxic decline in cyclin A and thymidylate synthase expression.Amsilarotene inhibits tumor growth in the liver with low toxicity and markedly improves survival in both primary HCC and metastatic colon cancer models. It was in phase II clinical development with Taiho Pharmaceutical for liver cancer, however it was discontinued.

Hydroxypioglitazone (M-IV) is an active metabolite of the peroxisome proliferator-activated receptor γ (PPARγ) agonist pioglitazone. Experiments in vitro have shown that hydroxypioglitazone was more efficient than the parent drug in stimulating lipid synthesis.

Palifosfamide or ZIO-201 (isophosphoramide mustard; IPM), a bi-functional DNA alkylator, is the active metabolite of ifosfamide (IFOS). IFOS and the related drug cyclophosphamide (CPA) are widely used anti-cancer drugs. Both are pro-drugs and need to be metabolized to be active. Their clinical use is limited by the toxicity associated with some of their metabolites. Palifosfamide has shown efficacy in diverse cancer models. ZIOPHARM Oncology Inc, under license from Dekk-Tec Inc, was developing palifosfamide, a formulation of isophosphoramide mustard with tris(hydroxymethyl)aminomethane salt-stabilization (palifosfamide-tris) and previously with lysine-stabilization (palifosfamide-lys). Preclinical studies and phase I and I/II clinical trials demonstrated that palifosfamide-tris had an antitumor efficiency comparable or superior to that of ifosfamide. To date ZIO-201 is not present in ZIOPHARM pipeline.

Ibiglustat (GZ/SAR402671 or Genz-682452) is a small molecule inhibitor of glucosylceramide synthase. Ibiglustat has been demonstrated to effectively lower glycosphingolipid synthesis. Genzyme, a Sanofi Company is developing Ibiglustat for the treatment of Parkinson's Disease, Gaucher Disease, and Fabry Disease.

Gimatecan is a topoisomerase I inhibitor that is presently tested in phase II of clinical trials for the treatment of different cancers: glioma, glioblastoma, epithelial ovarian cancer, fallopian tube or peritoneal cancer. The drug recieved orphan designation for the treatment of glioma.