PF-562271

PURPOSE: ;PF-00562271 is a novel inhibitor of focal adhesion kinase (FAK). The objectives of this study were to identify the recommended phase II dose (RP2D) and assess safety and tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and antitumor activity of PF-00562271.;PATIENTS AND METHODS: ;Part 1 was a dose escalation without and with food. Part 2 enrolled specific tumor types in an expansion at the RP2D and also assessed the effect of PF-00562271 on single-dose midazolam PK in a subgroup of patients.;RESULTS: ;Ninety-nine patients (median age, 60 years; 98% with Eastern Cooperative Oncology Group performance status of 0 or 1) were treated in 12 fasting and three fed cohorts. The 125-mg twice-per-day fed dose was deemed the maximum-tolerated dose (MTD) and RP2D. Grade 3 dose-limiting toxicities included headache, nausea/vomiting, dehydration, and edema. Nausea was the most frequently observed toxicity (60% of patients, all grades 1 or 2 at RP2D). PF-00562271 exposure increased with increasing dose; serum concentration-time profiles showed characteristic nonlinear disposition. Steady-state exposures were reached within 1 week. On coadministration, geometric mean values of midazolam maximal observed serum concentration and area under the serum concentration-time curve increased by 60% and more than two-fold, respectively.

Focal adhesion kinase (FAK) is a 125-kDa non-receptor and non-membrane protein tyrosine. FAK can function with integrins and growth factor receptors to promote cell survival dependent kinase activity and nuclear FAK promotes cell proliferation and survival through FERM (FAK, ezrin, radixin, moesin) domain-enhanced p53 degradation independent kinase activity. Many previous studies have indicated that FAK plays a critical role in the biological processes of normal and cancer cells and FAK has been proposed as a potential target in cancer therapy. Small molecule inhibitors (PF-573,228; PF-562,271 and NVP-226) for use as potential cancer therapies have been developed. However, the detailed mechanism of the role for FAK in tumor cell generation and progression remain unclear, so future work is needed to explore these issues. New inhibitors that can be effectively inhibit the function of FAK still need to be explored due to the low specificity, and resistance.

INTRODUCTION: ;Mammary tumorigenesis is associated with the increased expression of several proteins in the focal adhesion complex, including focal adhesion kinase (FAK) and various integrins. Aberrant expression of these molecules occurs concomitant with the conversion of TGF-beta function from a tumor suppressor to a tumor promoter. We previously showed that interaction between beta3 integrin and TbetaR-II facilitates TGF-beta-mediated oncogenic signaling, epithelial-mesenchymal transition (EMT), and metastasis. However, the molecular mechanisms by which the focal adhesion complex contributes to beta3 integrin:TbetaR-II signaling and the oncogenic conversion of TGF-beta remain poorly understood.;METHODS: ;FAK expression and activity were inhibited in normal and malignant mammary epithelial cells (MECs) either genetically by using lentiviral-mediated delivery of shRNAs against FAK, or pharmacologically through in vitro and in vivo use of the FAK inhibitors, PF-562271 and PF-573228. Altered Smad2/3 and p38 MAPK activation, migration, EMT, and invasion in response to TGF-beta1 were monitored in FAK-manipulated cells. TbetaR-II expression was increased in metastatic breast cancer cells by retroviral transduction, and the metastasis of FAK- and TbetaR-II-manipulated tumors was monitored by using bioluminescent imaging.