Peripheral CD45RO, PD-1, and TLR4 expression in metastatic colorectal cancer patients treated with bevacizumab, fluorouracil, and irinotecan (FOLFIRI-B).

CD45RO, PD-1, and TLR4 immune pathways have proven pivotal in regulating antitumor response and correlate with survival for localized colorectal cancer (CRC). We evaluated if their peripheral expression was associated with outcome in metastatic CRC (mCRC). Thirty-one mCRC patients were eligible for this prospective study ( clinicaltrial.gov NCT01533740) and treated with first-line FOLFIRI-B. Blood was drawn before the first and third cycle and analyzed by flow cytometry for frequency (%) of CD4+, CD8+, CD45RO+, and PD1+ mononuclear cells and for TLR4 expression on neutrophils. Two cycles of chemotherapy determined changes in immune variables that were prognostically meaningful. Pre-third-cycle (ptc) CD45RO+CD8+cell% displayed a statistically significant association with progression-free survival (PFS) (median PFS 22.4 vs. 9.4 months for patients with CD45RO+CD8+cell%> vs.