Companion Diagnostics and Cancer Biomarkers PTEN Expression as a Predictor of Response to FocalAdhesionKinase Inhibition inUterineCancer

PTEN is known to be frequently mutated in uterine cancer and also dephosphorylates FAK. Here, we examined the impact of PTEN alterations on the response to treatment with a FAK inhibitor (GSK2256098). In vitro and in vivo therapeutic experiments were carried out using PTEN-mutated and PTEN-wildtype models of uterine cancer alone and in combination with chemotherapy. Treatment with GSK2256098 resulted in greater inhibition of pFAK in PTEN-mutated (Ishikawa) than in PTEN-wild-type (Hec1A) cells. Ishikawa cells were more sensitive to GSK2256098 than the treated Hec1A cells. Ishikawa cells were transfected with a wild-type PTEN construct and pFAK expression was unchanged after treatment with GSK2256098. Decreased cell viability and enhanced sensitivity to chemotherapy (paclitaxel and topotecan) in combination with GSK2256098 was observed in Ishikawa cells as compared with Hec1a cells. In the Ishikawa orthoptopic murine model, treatment with GSK2256098 resulted in lower tumor weights and fewer metastases than mice inoculated with Hec1A cells. Tumors treated with GSK2256098 had lower microvessel density (CD31), less cellular proliferation (Ki67), and higher apoptosis (TUNEL) rates in the Ishikawa model when compared with the Hec1a model. From a large cohort of evaluable patients, increased FAK and pFAK expression levels were significantly related to poor overall survival. Moreover, PTEN levels were inversely related to pFAK expression. These preclinical data demonstrate that PTEN-mutated uterine cancer responds better to FAK inhibition than does PTEN wild-type cancer. Therefore, PTEN could be a biomarker for predicting response to FAK-targeted therapy during clinical development. Mol Cancer Ther; 14(6); 1466–75. 2015 AACR. Introduction Uterine cancer is the most common gynecologic cancer in the United States (1) and the sixth most common cancer in women worldwide (2). In 2014, an estimated 52,630 new cases of uterine cancer were diagnosed in the United States, and 8,590 patients died of their disease. Five-year survival rates in patients with regional and distant metastasis remain poor, at 67% and 17%, respectively (1). Advanced and recurrent uterine cancers are resistant to traditional chemotherapeutic regimens, pointing to an urgent need for novel drugs and treatment strategies (3). Development of targeted biologic therapies is essential to control locally advanced, metastatic, and recurrent uterine cancer. Focal adhesion kinase (FAK) is a nonreceptor protein tyrosine kinase that is overexpressed in many types of human cancer cells, portending a poor prognosis and decreased survival duration. Previous studies demonstrated a role for FAK in tumor angiogenesis, migration, invasion, and metastasis (4–6). Overexpression and increased phosphorylation of FAK is known to confer a more malignant phenotype of uterine cancer (7). PTEN located on chromosome 10 is a lipid phosphatase tumor suppressor gene. Its loss of function by multiple mechanisms is considered to be a causal event in thedevelopment of uterine cancer (8–12). Somatic PTEN mutations have been identified in 34% to 55% of endometrial cancers, (11, 13) and the majority of these are frameshift or point mutations. The loss of PTEN can result from mutations, abnormalities in transcription, regulation of miRNAs by PTEN pseudogenes, or other epigenetic changes. PTEN is known to negatively regulate FAK (14, 15). Mutated PTEN and overexpression of FAK can lead to an uncontrolled PI3K–AKT signaling pathway, which can affect downstream signaling and compromise mismatch repair processes. These DNA mismatch repair abnormalities are common features seen in type I uterine cancers (16–18). It is not known whether the interaction between FAK and PTEN has an impact on response to FAK-targeted drugs. Small molecules that target FAK are attractive for uterine and other cancers. GSK2256098 (GlaxoSmithKline) is a smallmolecule, ATP-competitive, reversible inhibitor that targets FAK activity and Y397 phosphorylation. It is highly selective for FAK and is much more selective for FAK than Pyk2, the nearest Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MDAnderson Cancer Center, Houston, Texas. Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand. Center for RNA Interference and Non-Coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, Texas. Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan. DepartmentofCancerBiology,TheUniversity of Texas MD Anderson Cancer Center, Houston, Texas. Note: Supplementary data for this article are available at Molecular Cancer Therapeutics Online (http://mct.aacrjournals.org/). D. Thanapprapasr and R.A. Previs contributed equally to this article. Corresponding Author: Anil K. Sood, Departments of Gynecologic Oncology and Cancer Biology, Unit 1362, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77230. Phone: 713-745-5266; Fax: 713-792-7586; E-mail: [email protected] doi: 10.1158/1535-7163.MCT-14-1077 2015 American Association for Cancer Research. Molecular Cancer Therapeutics Mol Cancer Ther; 14(6) June 2015 1466 on June 25, 2017. © 2015 American Association for Cancer Research. mct.aacrjournals.org Downloaded from Published OnlineFirst April 1, 2015; DOI: 10.1158/1535-7163.MCT-14-1077