Importance of the field: Discovery of small molecule inhibitors for treatment of rheumatoid arthritis is a major ongoing effort within the pharmaceutical industry. Spleen tyrosine kinase (SYK) is one of the leading small molecular targets with regard to clinical developments due to the efforts of Rigel and Portola.
Areas covered in this review: Diaminopyrimidines are one of the most prominent structural elements incorporated into the design of kinase inhibitors. This review provides an extensive overview of the patent estates for the leading discovery programs at Portola and Rigel on diaminopyrimidines and how their patent estates are in relationship with the competition and prior art.
What the reader will gain: An overview of the patent landscape for diaminopyrimidines. In addition, the reader will be updated on what modifications in these scaffolds lead to very potent SYK inhibitors as judged by the applications. Finally, the authors will provide their best guess on what the structure is of Portola's recently announced clinical candidate.
Take home message: The Rigel and the Portola research organizations have filed a series of patent applications on diaminopyrimidines as inhibitors of SYK. The scope of these applications is broad in a crowded chemical space. These applications contain very broad claims and the future will tell how much of the generic space claimed will be allowed in granted patents.