Roniciclib (BAY1000394) is a pan-cyclin-dependent kinase inhibitor that has been developed for treatment in small cell lung carcinoma and solid tumors. Roniciclib targets certain key proteins that are essential for the survival of cancer cells, resulting in decreased tumor growth. Phase I studies to evaluate the safety, tolerability and pharmacokinetics of roniciclib have been completed successfully. In phase II studies, roniciclib was found to be well tolerated and showed promising efficacy when combined with chemotherapy in small cell lung carcinoma patients. However, due to an observed safety signal (treatment-emergent adverse events) in one phase II study, other clinical trials have been discontinued and further development of roniciclib was terminated.

SNS-032 (formerly BMS-387032) is a potent, selective inhibitor of cyclin-dependent kinases (CDK). SNS-032 blocks the cell cycle via inhibition of CDKs 2 and 7, and transcription via inhibition of CDKs 7 and 9. SNS-032 was investigated for the treatment of solid tumors and hematologic malignancies (Phase I studies), however, its development was discontinued.

An orally bioavailable inhibitor of cyclin-dependent kinases (CDKs) and thropomyosin receptor kinase A (TRKA), with potential antineoplastic activity. CDK2/TRKA inhibitor PHA-848125 AC potently inhibits cyclin-dependent kinase 2 (CDK2) and exhibits activity against other CDKs including CDK1 and CDK4, in addition to TRKA. Inhibition of these kinases may result in cell cycle arrest and apoptosis of tumor cells that express these kinases. Milciclib is currently in phase II clinical trials for thymic carcinoma, glioma and liver cancer. The most common adverse events are nausea and asthenia, vomiting, myasthenic syndrome, dehydration, hypophosphatemia, cytolytic hepatitis and plantar fasciitis.

AZD-5438 is an anti-cancer medicine which was developed by AstraZeneca. The drug is under development for the treatment of solid tumors in phase I of clinical trials. AZD-5438 exerts its anti-proliferative action both in vitro and in vivo by inhibiting cyclin-dependent kinases 1, 2 and 6 which are involved in the cell cycle.

CVT 313 is the lead compound in a series of small molecule cell cycle inhibitors that inhibit cyclin-dependent kinase 2 (CDK2). It was in development with CV Therapeutics in the USA. CVT 313, in combination with drug delivery catheters and as coatings on endoluminal stents, may have potential in the prevention of restenosis. In February 1998, CV Therapeutics signed a research agreement with The Cleveland Clinic Foundation for the preclinical testing of CVT 313. In February 1999 CV Therapeutics announced the granting of a patent for purine inhibitors of CDK2 by the USA Patent and Trademark Office. No recent development of CVT 313 has been reported.

BMS 265246 is a potent inhibitor of cyclin dependent kinase 1 and 2. It was under investigation with BristolMyers Squibb in the USA with potential in the treatment of cancer, however, BristolMyers Squibb no longer lists this product on its research and development pipelines which suggests that development of the programme has been discontinued.

Indirubin is derived from the Indigo Plant (Isatis Root, Isatis Leaf). It is used as part of a traditional Chinese herbal prescription called Dang Gui Long Hui Wan, to treat chronic myelogenous leukemia (CML). Indirubin inhibits DNA synthesis in several cell lines, in a cell-free assay and in vivo in rats with Walker-256 sarcoma. A weak binding of indirubin to DNA in vitro has been described. Indirubin inhibited all cyclin-dependent kinases (1,2,4,5) almost equally. Indirubin has been approved for clinical trials against chronic myelocytic and chronic granulocytic leukaemia. A few studies show that Indirubin is effective against psoriasis. Mild to severe nausea, vomiting, abdominal pain, diarrhea, headache, and edema are reported adverse events of Indirubin. Long-term oral ingestion has also occasionally been associated with hepatitis, pulmonary arterial hypertension and cardiac insufficiency.

An orally bioavailable inhibitor of cyclin-dependent kinases (CDKs) and thropomyosin receptor kinase A (TRKA), with potential antineoplastic activity. CDK2/TRKA inhibitor PHA-848125 AC potently inhibits cyclin-dependent kinase 2 (CDK2) and exhibits activity against other CDKs including CDK1 and CDK4, in addition to TRKA. Inhibition of these kinases may result in cell cycle arrest and apoptosis of tumor cells that express these kinases. Milciclib is currently in phase II clinical trials for thymic carcinoma, glioma and liver cancer. The most common adverse events are nausea and asthenia, vomiting, myasthenic syndrome, dehydration, hypophosphatemia, cytolytic hepatitis and plantar fasciitis.

Indirubin is derived from the Indigo Plant (Isatis Root, Isatis Leaf). It is used as part of a traditional Chinese herbal prescription called Dang Gui Long Hui Wan, to treat chronic myelogenous leukemia (CML). Indirubin inhibits DNA synthesis in several cell lines, in a cell-free assay and in vivo in rats with Walker-256 sarcoma. A weak binding of indirubin to DNA in vitro has been described. Indirubin inhibited all cyclin-dependent kinases (1,2,4,5) almost equally. Indirubin has been approved for clinical trials against chronic myelocytic and chronic granulocytic leukaemia. A few studies show that Indirubin is effective against psoriasis. Mild to severe nausea, vomiting, abdominal pain, diarrhea, headache, and edema are reported adverse events of Indirubin. Long-term oral ingestion has also occasionally been associated with hepatitis, pulmonary arterial hypertension and cardiac insufficiency.