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Narra K , Mullins SR , Lee HO , Strzemkowski-Brun B , Magalong K , Christiansen VJ , McKee PA , Egleston B , Cohen SJ , Weiner LM , Meropol NJ , Cheng JD
Phase II trial of single agent Val-boroPro (Talabostat) inhibiting Fibroblast Activation Protein in patients with metastatic colorectal cancer
Cancer Biol Ther. 2007 Nov;6(11) :1691-9
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PURPOSE: Fibroblast Activation Protein (FAP) is a tumor fibroblast protease that has been shown to potentiate colorectal cancer growth. The clinical impact of FAP inhibition was tested using Val-boroPro (Talabostat), the first clinical inhibitor of FAP enzymatic activity, in a phase II study of patients with metastatic colorectal cancer. METHODS: Patients with metastatic colorectal cancer who had previously received systemic chemotherapies were treated with single agent Val-boroPro 200 microg p.o. BID continuously. Eligibility included measurable disease, performance status of 0 to 2, and adequate organ function. Laboratory correlates evaluated the pharmacodynamic effects of Val-boroPro on FAP enzymatic function in the peripheral blood. RESULTS: Twenty-eight patients (median age 62; 12 males, 16 females) were enrolled in this study. There were no objective responses. Six of 28 (21%) patients had stable disease for a median of 25 weeks (range 11-38 weeks). Laboratory analysis demonstrated significant, although incomplete inhibition of FAP enzymatic activity in the peripheral blood. CONCLUSION: This phase II trial of Val-boroPro demonstrated minimal clinical activity in patients with previously treated metastatic colorectal cancer. However it provides the initial proof-of-concept that physiologic inhibition of FAP activity can be accomplished in patients with colorectal cancer, and lays the groundwork for future studies targeting the tumor stroma.
Narra, Kalyani Mullins, Stefanie R Lee, Hyung-Ok Strzemkowski-Brun, Brenda Magalong, Kimberly Christiansen, Victoria J McKee, Patrick A Egleston, Brian Cohen, Steven J Weiner, Louis M Meropol, Neal J Cheng, Jonathan D eng CA006927/CA/NCI NIH HHS/ CA090468/CA/NCI NIH HHS/ CA122301/CA/NCI NIH HHS/ HL072995-01/HL/NHLBI NIH HHS/ Clinical Trial, Phase II Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't Cancer Biol Ther. 2007 Nov;6(11):1691-9. doi: 10.4161/cbt.6.11.4874. Epub 2007 Aug 14.