P276-00 (also known as riviciclib) is a novel, potent, small-molecule, flavone-derived inhibitor of cyclin-dependent kinases (Cdk), Cdk 4 D1, Cdk1 B, and Cdk9 T, with potent cytotoxic effects against chemosensitive and chemoresistant cancer cell lines. P276-00 was in phase II clinical trial for the treatment mantle cell lymphoma, but that study was terminated based on interim results and all subjects were off study at that time. Although, there were not the major safety or tolerability concerns. However, this drug successfully passed phase II clinical trial for the treatment Melanoma, squamous cell carcinoma of head and neck, malignant melanoma and in combination with Gemcitabine in the treatment of advanced pancreatic cancer.

A diaminopyrimidine compound R547 is a small molecule selective ATP-competitive inhibitor of cyclin-dependent kinases CDK1, CDK2 and CDK4 and has excellent in vitro cellular potency, inhibiting the growth of various human tumor cell lines. In vivo, R547 showed antitumor activity in all of the models tested to date, including six human tumor xenografts and an orthotopic syngeneic rat model. R547 was being developed by Roche for the treatment of solid tumours. The compound was undergoing clinical development in the US. However, no recent development has been reported and it is assumed to have been discontinued.

AT7519M or AT7519, a small molecule inhibitor of cyclin-dependent kinases 1, 2, 4, 5, and 9, participated in phase II clinical trials in patients with relapsed or refractory chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL). As a result, in CLL, some patients had tumor reductions, but the objective response rate (ORR) was low. In MCL, activity was noted with ORR of 27%. In addition, AT7519M was studied in patients with previously treated multiple myeloma, to understand whether the drug alone or in combination with bortezomib were effective treatments. Recent experiments also have shown that AT7519 is a promising drug for the treatment of high-risk neuroblastoma patients with MYCN amplification. It is known, that MYCN-dependent neuroblastomas have low cure rates with current multimodal treatment.