Small-Molecules Targeting Kinases Involved in Pulmonary Hypertension: a Patent Review (2010-2015)

Despite the fact that in recent years, a substantial progress has been made in the treatment of pulmonary hypertension, it is still a severe disease characterized by poor prognosis, and the search for new drugs remains a priority. Current remedies address mainly the vasoconstrictor/ vasodilator imbalance in the pulmonary circulation, while the causes of the disease are only moderately affected. Recently, the role of receptor and non receptor kinases in pulmonary hypertension has emerged and these targets were extensively considered for the development of new therapeutic strategies. This review discusses the patents on small-molecules targeting kinases involved in the proliferation/apoptosis imbalance, typically present in pulmonary hypertension.

Bibliographic research for the inventions was carried out using Espacenet and Sci-Finder databases, "pulmonary hypertension and kinases" as research query and the range from 2010 to 2015. Only patents published in English were considered. A qualitative analysis of the contents of each patent was made to examine the reported compounds, the studies performed and the resulting conclusions.

The review includes about thirty applications. Moreover, in order to illustrate the pathophisiology of the disease and the mechanisms of the targets, about forty additional papers were reported. Considering that imatinib, a PDGF receptor inhibitor, entered the clinical trials for the treatment of pulmonary hypertension, the first patents were devoted to inhibitors of tyrosine kinase receptors, such as PDGFR and c-Kit. Subsequently, in addition to kinase receptors, the role of other pathways involved in pulmonary hypertension has emerged, and some research groups have focused their attention also on non-receptor kinases. Fifteen patents on this topic reported these new targets and new derivatives. However, in most of the inventions, although the pulmonary hypertension is among the treatable diseases, the compounds were subjected only to antiproliferative assays and not to specific tests on animal models.

The studies reported in this review confirm the continuous research efforts aimed to identify new targets and new drugs for the treatment of pulmonary hypertension. Several inhibitors of kinase were described. These compounds could inhibit mainly important branching processes and pathological growth of blood vessels, thereby might increase the lifespan of patients.