402P - Inflammatory biomarkers for predicting the efficacy of immunotherapy in advanced breast cancer

Background

Immune checkpoint inhibitors have demonstrated clinical benefits in breast cancer but still lack predictive efficacy indicators. We aim to investigate the significance of inflammatory markers as indicators of immunotherapy efficacy in patients with all subtypes of advanced breast cancer (ABC).

Methods

This retrospective study enrolled 116 patients with ABC who were treated with programmed cell death protein 1 (PD-1) inhibitors between January 2016 and June 2022 at Sun Yat-sen University Cancer Center. Data on clinicopathological characteristics at baseline and several inflammatory markers before and after three courses of immunotherapy were collected. After obtaining optimal cut-off by R, the association of inflammatory markers with the objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were analysed.

Results

The lymphocyte-to-monocyte ratio (LMR), neutrophil-to-lymphocyte ratio (NLR), and C-reactive protein (CRP) at baseline and LMR, NLR, and CRP levels after three courses of immunotherapy (LMR3, NLR3, CRP3) were significantly associated with PFS and OS. Interestingly, subgroup analyses showed that OS was longer in the human epidermal growth receptor 2(HER2) low-expression group than in the HER2-negative group (27.83 vs 16.60 months, P=0.03). In all patients, multivariate Cox regression analysis showed that low level of CRP3 (CRP3 ≤ 2.95 vs. CRP3 > 2.95, HR = 0.510; 95% CI, 0.292-0.889; P = 0.018) and lower CRP3 compared to baseline (CRP3/CRP ≤ 4.44 vs CRP3/CRP > 4.44, HR = 0.467, 95% CI, 0.222-0.983, P = 0.045) were significantly associated with longer PFS. Meanwhile, the group with low level of NLR before (NLR ≤ 4.79 vs NLR > 4.79, HR = 0.383; 95% CI, 0.168-0.869; P = 0.022) and after (NLR3 ≤ 1.94 vs NLR3 > 1.94, HR = 0.370, 95% CI, 0.142-0.960, P = 0.041) immunotherapy, the patients with low level of CRP at baseline (CRP ≤ 15.52 vs CRP > 15.52, HR = 0.142; 95% CI, 0.050-0.404; P < 0.001), as well as the cohort with slower growth of CRP3 compared to baseline (CRP3/CRP ≤ 4.44 vs. CRP3/CRP > 4.44, HR = 0.347, 95% CI, 0.133-0.901, P = 0.030), had better OS.

Conclusions

In conclusion, peripheral blood NLR and CRP, which are easy to detect, may be potential biomarkers for predicting the efficacy of immunotherapy in ABC.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Beijing Xisike Clinical Oncology Research Foundation.

Disclosure

All authors have declared no conflicts of interest.