Correlation of TROP2 expression with clinico-pathological features and outcomes in HR+/HER2- breast cancer receiving neoadjuvant chemotherapy.

Background: Limited data exists about the associations between TROP2 protein, clinico-pathological characteristics, and outcomes in patients with an early HR+/HER2- breast cancer (BC).

Patients And Methods: TROP2 membranous expression was assessed on tumor biopsy by immunohistochemistry (IHC) in 70 consecutive patients with HR+/HER2- BC who are eligible for neoadjuvant chemotherapy (NAC). TROP2 expression was correlated to initial clinico-pathological parameters and pathological response post-NAC. Furthermore, Transcriptomics analysis of TACSTD2 using SCAN-B and GSE81538 datasets was performed and correlated with clinico-pathological parameters and survival.

Results: All patients showed TROP2 IHC expression, with intermediate and high expression in 68.57% and 31.43%, respectively. High TROP2 expression showed a significant correlation with high Ki-67 pre-NAC (P = .017), while no significant correlation with pCR or residual cancer burden. High TACSTD2 expression was associated with significantly lower histological grade (P < .0001), earlier tumor stage (P < .0001), smaller tumor size (< 20 mm, P < .0001), lower Ki-67 (P < .0001), and longer overall-survival (HR = 0.76; P = .0008), recurrence-free survival (RFS; HR = 0.64; P = .0001) and distant-RFS (HR = 0.64; P = .0011).

Conclusions: In this study, TROP2 expression by IHC was observed in all HR+/HER2- BC cases, and was not significantly correlated with pCR to NAC. In contrast, TACSTD2 expression, which was significantly positively correlated with survival in the same population, suggests a favorable prognostic value at the transcript level. This finding warrants further investigation in future studies, particularly focusing on TACSTD2 expression at the mRNA rather than the protein level.