Combination therapy with anti-PD-L1 and anti-IL-8 significantly enhanced tumor growth inhibition in models, achieving 51.28% inhibition compared to 39.13% for monotherapy.
Significantly higher tumor growth inhibition was observed with combination therapy in responsive donor models.
Single-cell RNA sequencing indicated a higher proportion of T-cells within tumors treated with combination therapy.
The BP2402 showed high binding affinity for both IL-8 and PD-L1.
BP2402 treatment resulted in reduced levels of CXCL8 and VEGFA, which are associated with tumor growth.
Combination therapy modulated immune markers, suggesting a potential to address T cell exhaustion.
Simplified
BACKGROUND: (TNBC) is an aggressive malignancy with limited therapeutic options. Immune checkpoint inhibitors targeting the programmed death-ligand 1 (PD-L1) pathway show restricted efficacy in TNBC, with response rates of only 5-10% as monotherapy. Interleukin-8 (IL-8/CXCL8) signaling promotes immunosuppression and mediates resistance to anti-PD-L1 therapy, necessitating combination approaches to overcome these limitations. However, the underlying mechanisms of enhanced efficacy from dual pathway targeting require further investigation.
METHODS: We generated humanized mouse models by reconstituting immunodeficient mice with human PBMCs from five donors (n = 5 mice/group). MDA-MB-231 TNBC cells were implanted subcutaneously, and mice were treated with vehicle control, atezolizumab (anti-PD-L1), HuMax-IL8 (anti-IL-8), combination therapy, or a novel BP2402 targeting both PD-L1 and IL-8. Antitumor activity was assessed alongside single-cell RNA sequencing of tumors and mechanistic analyses including immunofluorescence and Western blot.
RESULTS: Combination therapy demonstrated significantly enhanced tumor growth inhibition compared to atezolizumab monotherapy in responsive donor models (51.28% vs. 39.13% for donor 3, p < 0.01; 44.01% vs. 6.57% for donor 4, p < 0.01). Single-cell RNA sequencing showed higher intratumoral T-cell fractions with combination therapy (donor 3: 80.5% vs. 26.7%; donor 4: 63.6% vs. 13.0% compared to control). BP2402 maintained high binding affinity for both IL-8 (KD = 2.132 nM) and PD-L1 (KD = 1.473 nM), and demonstrated superior antitumor efficacy compared to monotherapies (p < 0.001 vs. vehicle, p < 0.01 vs. individual antibodies). BP2402 treatment significantly reduced CXCL8 and VEGFA expression, suppressed JAK1/STAT1 signaling pathway activation, and upregulated pro-apoptotic proteins including FAS and BAX while effectively modulating T cell exhaustion markers PD-1 and TIM-3.
CONCLUSIONS: These results indicate that dual targeting of PD-L1 and IL-8 pathways represents a promising therapeutic strategy for TNBC. The bispecific antibody approach offers superior therapeutic potential by simultaneously modulating immune checkpoints, inflammatory signaling, and angiogenesis, effectively addressing resistance mechanisms. Additional preclinical optimization and clinical studies are required to fully assess the therapeutic potential of this novel immunotherapeutic approach.
Key numbers
51.28%
Increase in Tumor Growth Inhibition
Tumor growth inhibition in donor 3 model with combination therapy vs. PD-L1 monotherapy.
80.5%
T Cell Proportion Increase
T cell fraction in tumors from donor 3 with combination therapy vs. control.
2.132 nM
Reduction in CXCL8 Expression
Equilibrium dissociation constant (KD) for BP2402 binding to IL-8.
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Declarations. Ethics approval and consent to participate: The PBMCs used in this study were obtained from healthy donors and patients recruited at Shanghai Zhaxin Hospital of Traditional Chinese and Western Medicine. All PBMC collection and screening procedures were conducted under the approval of the Ethics Committee of Shanghai Zhaxin Hospital of Traditional Chinese and Western Medicine (approval number: XF0102232W) and in full compliance with the Declaration of Helsinki and medical ethics guidelines. All donors met the established inclusion criteria and were screened according to standard clinical protocols. Consent for publication: Not applicable. Competing interests: The authors disclose no conflicts of interest.
