SDF-1 expression and tumor-infiltrating lymphocytes identify clinical subtypes of triple-negative breast cancer with different responses to neoadjuvant chemotherapy and survival

Paclitaxel, interferons and functional reprogramming of tumor-associated macrophages in optimized chemo-immunotherapy

Immune checkpoint inhibition (ICI) targeting programmed cell death protein-1 (PD1) prevents the elimination of activated cytotoxic T lymphocytes (CTLs) by programmed death-ligand 1/2-expressing cancer and myeloid cells in the tumor microenvironment (TME). ICI has shown its effectiveness in many solid tumors, but it lacks activity against "cold" tumors which lack CTL infiltration, including most of the colon, prostate, lung and breast cancers. Metastatic triple-negative breast cancer (TNBC) responds to PD-1 blockade only in 5-20% cases. Chemotherapy has been shown to have a PD1-sensitizing effect in a fraction of patients with TNBC but the underlying mechanism and the reasoning behind its limitation to only a subset of patients are unknown. Recent data demonstrate the key roles played by paclitaxel-driven Toll-like receptor 4 (TLR4) signaling and the resulting activation of type-1 and type-2 interferon pathways in tumor-associated macrophages, resulting in local M2 to M1 transition and enhanced tumor antigen cross-presentation, in the paclitaxel-driven sensitization of "cold" tumors to ICI. These data and the known ability of the TLR4-activated MyD88-NFκB pathway to mobilize both antitumor and tumor-promoting events in the TME provide new tools to enhance the efficacy of chemo-immunotherapy for metastatic, and potentially early, TNBC and other taxane-sensitive cancers.

Predictive value of stromal tumor-infiltrating lymphocytes in patients with breast cancer treated with neoadjuvant chemotherapy: A meta-analysis

BACKGROUND

The predictive value of tumor-infiltrating lymphocytes (TILs) in response to neoadjuvant chemotherapy (NAC) for breast cancer (BC) has received increasing attention. Here, a meta-analysis was conducted to evaluate the correlation between the expression of stromal TILs and pathological complete response (pCR) after NAC in BC patients.

METHODS

The PubMed, Embase, Cochrane Library, and Web of Science databases were searched online by using a combination of keywords and free words to screen literature on the expression of stromal TILs and pCR after NAC in patients with BC. The data were extracted and evaluated for quality. Relative risk (RR) was used to evaluate the relationship between the expression of stromal TILs before NAC and pCR in BC patients. Meta-analysis was performed with Review Manager 5.3 and STATA 14.0 software.

RESULTS

Eleven studies involving 6039 BC patients were included in the meta-analysis. The results showed a generally high expression of stromal TILs in BC patients, and the pCR rate after NAC in BC patients with a high expression of stromal TILs was significantly higher than that in BC patients with a low expression of stromal TILs [RR = 1.83, 95% confidence interval (CI): 1.69-1.97]. Subgroup analysis based on the molecular subtypes of BC showed that the pCR rate was significantly higher in patients with a high expression of stromal TILs in hormone receptor (HR)-positive BC [RR = 3.23, 95% CI: 2.43-4.30], human epidermal growth factor receptor 2 (HER-2)-positive BC [RR = 1.41, 95% CI: 1.25-1.60], and triple-negative BC [RR = 1.70, 95% CI: 1.53-1.90] than in those with a low expression of stromal TILs. Subgroup analysis based on expression threshold showed that the pCR rate was higher in patients with a high expression of stromal TILs than in patients with a low expression of stromal TILs at different expression thresholds (10% [RR = 1.99, 95% CI: 1.55-2.55], 20%/30% [RR = 1.57, 95% CI: 1.37-1.81], 50%/60% [RR = 1.91, 95% CI: 1.73-2.11].

CONCLUSION

TILs can be used as a predictor of pCR after NAC in patients with BC, and the appropriate high expression threshold of stromal TILs should be selected as the predictive value according to the molecular subtype of BC.