Molecular and Dynamic Evaluation of Proteins Related to Resistance to Neoadjuvant Treatment with Chemoradiotherapy in Circulating Tumor Cells of Patients with Locally Advanced Rectal Cancer

Abstract

The heterogeneity of response to neoadjuvant chemoradiotherapy (NCRT) is still a challenge in locally advanced rectal cancer (LARC). The evaluation of thymidylate synthase (TYMS) and RAD23 homolog B (RAD23B) expression in circulating tumor cells (CTCs) provides complementary clinical information. CTCs were prospectively evaluated in 166 blood samples (63 patients) with LARC undergoing NCRT. The primary objective was to verify if the absence of RAD23B/TYMS in CTCs would correlate with pathological complete response (pCR). Secondary objectives were to correlate CTC kinetics before (C1)/after NCRT (C2), in addition to the expression of transforming growth factor-β receptor I (TGF-βRI) with survival rates. CTCs were isolated by ISET and evaluated by immunocytochemistry (protein expression). At C1, RAD23B was detected in 54.1% of patients with no pCR and its absence in 91.7% of patients with pCR (p = 0.014); TYMS− was observed in 90% of patients with pCR and TYMS+ in 51.7% without pCR (p = 0.057). Patients with CTC2 > CTC1 had worse disease-free survival (DFS) (p = 0.00025) and overall survival (OS) (p = 0.0036) compared with those with CTC2 ≤ CTC1. TGF-βRI expression in any time correlated with worse DFS (p = 0.059). To conclude, RAD23B/TYMS and CTC kinetics may facilitate the personalized treatment of LARC.

Metastasis risk stratification and response prediction through dynamic viable circulating tumor cell counts for rectal cancer in a neoadjuvant setting

“…Since CTCs detected by our method are more likely to reflect the grade of dissemination for viable tumor cells in the circulatory system, it is reasonable that a moderate association was observed only between changes in the CTC count and the local therapeutic response. More molecular markers may help improve the accuracy, as reported by Silva et al 16 and Flores et al 17 …”

“…Since CTCs detected by our method are more likely to reflect the grade of dissemination for viable tumor cells in the circulatory system, it is reasonable that a moderate association was observed only between changes in the CTC count and the local therapeutic response. More molecular markers may help improve the accuracy, as reported by Silva et al 16 and Flores et al 17 However, the majority of previous studies failed to show or did not report a relationship with long-term prognosis, which may be related to the sensitivity of the methods used. CTCs were detected in 90% of the patients in the current study, while the detection rate in other studies that used the size-based method was relatively low (19%).…”

“…Extensive studies have been conducted in CRC, with a definite prognostic effect reported, 12,13 and long‐term efficacy can be predicted in both metastatic CRC (mCRC) and nonmetastatic CRC after surgery; however, only a few studies 14–19 have reported the impact of CTCs on the short‐term efficacy of preoperative CRT. Thus, the impact of baseline CTCs on long‐term oncological results for LARC has not yet been adequately characterized in a neoadjuvant setting 16 …”

“…Thus, the impact of baseline CTCs on long-term oncological results for LARC has not yet been adequately characterized in a neoadjuvant setting. 16 Immortalization is one of the basic characteristics of tumors, and it is realized through telomerase reverse transcriptase (TERT). The core of the approach we used in this study is the positive labeling of TERTpositive cells.…”

“…In recent years, increasing evidence has shown that liquid biopsy, which encompasses circulating tumor DNA 10 and circulating tumor cells (CTCs), 11 can be used as a prognostic tool in a variety of tumors, with the advantages of minimal invasiveness and easy dynamic monitoring. Extensive studies have been conducted in CRC, with a definite prognostic effect reported, 12 , 13 and long‐term efficacy can be predicted in both metastatic CRC (mCRC) and nonmetastatic CRC after surgery; however, only a few studies 14 , 15 , 16 , 17 , 18 , 19 have reported the impact of CTCs on the short‐term efficacy of preoperative CRT. Thus, the impact of baseline CTCs on long‐term oncological results for LARC has not yet been adequately characterized in a neoadjuvant setting.…”