Loss or mutations in the tumor suppressor gene TP53 (encoding p53) is one of the most frequent events in cancer. Clinical and functional studies have unequivocally validated the functional importance of the loss of p53 in cancer but unfortunately there are no small molecule approaches to address this challenge. Our labs have recently demonstrated that the kinase activity of type 2 phosphatidylinositol-5-phosphate 4-kinase A and B (PIP4K2A and B) encoded by PIP4K2A and PIP4K2B genes are crucial for the growth of cancers that harbor TP53 deletions. Specifically we have demonstrated that germ line deletion of PIP4K2A and PIP4K2B in mice suppresses tumor formation in the context of TP53 deletion and that prototype inhibitors selectively kill cells harboring TP53 deletions. The goal of this proposal is to develop the first covalent PIP4K2 inhibitors with the requisite potency, selectivity and pharmacological properties to interrogate the potential of PIP4K2 as a therapeutic target in lung cancer and other diseases characterized by loss of p53 function and high level of PIP4K2s. We have developed a prototype covalent PIP4K2 inhibitor, THZ-2-72-1, which irreversibly targets PIP4K2 and selectively inhibits the proliferation of p53 deficient lung cancer cell lines. We will use a focused medicinal chemistry approach informed by modeling and co-crystal structures to develop optimized inhibitors that can be tested using xenograft, genetically engineered and primagraft models for their ability to inhibit TP53-deficient tumor growth. These studies will serve to pharmacologically validate PIP4K2 as a new target and will provide prototype drugs that can be further optimized for eventual clinical testing.
Worldwide, lung cancer is the leading cancer killer accounting for 1.37 million deaths annually. Lung cancer arises as a result of environmental exposures, such as smoking, combined with genetic alterations such as deregulation or loss of key proteins that control cell growth. One protein that is frequently lost in many cancers, including lung cancer, is p53. The loss of p53 makes it easier for precancerous cells to progress to a cancerous state. We have discovered that the loss of p53 makes cancer cells uniquely vulnerable to drugs that disable another protein called PIP4K2. The goal of this research proposal is to develop and investigate whether prototype drugs targeting PIP4K2 will work in preclinical models of p53 deficient lung cancer. This research will serve to validate whether PIP4K2 is indeed a promising drug target and will provide starting points for drugs that can be advanced into clinical trials.