MA13.09 Cisplatin Sustains Lung Cancer Metastasis Through the Systemic Activation of SDF-1/CXCR4 Axis

Abstract

Standard chemotherapy regimens have limited long-term efficacy in lung cancer patients due to chemoresistance and inefficacy in controlling metastatic disease. In pre-clinical models we have shown that cisplatin treatment enriches for the chemoresistant fraction of CD133+CXCR4+ lung cancer metastasis initiating cells (MICs), increasing distant metastasis development that can be prevented by CXCR4 blockade. Therefore, we hypothesize that the SDF-1/CXCR4 axis, implied in MICs maintenance/migration and in immune and stromal cells trafficking, could play a critical role in cisplatin-induced pro-metastatic effects. To study the effects of cisplatin in promoting a pre-metastatic niche, naïve SCID mice were treated with cisplatin plus/minus peptide R (5mg/kg), a novel inhibitor of CXCR4 and after 72h injected intravenously with metastatic H460 cell line. To assess the effect of the combination treatment in pre-clinical model, H460 subcutaneous xenografts were treated with cisplatin alone or with peptide R for three weeks. Content of MICs in xenografts, number and phenotype of lung metastasis and immune cells modulationt were evaluated by FACS and IHC We showed that cisplatin treatment of naïf SCID mice resulted in a rapid BM expansion of the subset of CCR2+CXCR4+Ly6Chigh inflammatory monocytes (IM), concomitantly with their recruitment to murine lungs guided by increased level of SFD-1 released by PDGFRβ+ stromal cells in response to cisplatin. Peptide R partially prevented these effects. Tail-vein injection of H460 human lung cancer cells 72h after cisplatin administration resulted in augmented number of lung metastases (p=0.003), that showed a 3.5-fold enrichment in CD133+CXCR4+ MICs (p=0.005) and increase of IM and derived macrophages. Pre-treatment with peptide R abolished these effects. We verified that the abundance of CXCR4+CCR2+IM together with increased endothelial permeability caused by cisplatin may favor tumor cells extravasations and expansion of MICs through SDF-1/CXCR4 axis activation which determined metastasis overgrowth. SDF-1 was also increased in cisplatin-treated subcutaneous H460 xenografts that expanded the subset of chemoresistant CD133+CXCR4+ MICs and recruited CXCR4+tumor associated macrophages which may allow MICs to escape primary tumor. At the metastatic site cisplatin treatment of H460 xenografts caused an increase in stromal SDF-1 and recruitment of both CXCR4+ inflammatory monocytes/macrophages (1.6-fold change p=0.01) and MICs subset (1.8-fold change p=0,04), overall resulting in a boost in micrometastases. CXCR4 inhibition prevented the co-recruitment and cross-talk of MICs and IM at distant site, counteracting the pro-metastatic effects of cisplatin. Matched case series of stage III chemo-naive NSCLC patients and cisplatin-based neo-adjuvant treated patients demonstrated a significant increased in SDF-1 after chemotherapy (p=0,0001). An high expression of tumoral SDF-1 (Score: staining intensity x % positive tumor cells >6) induced by cisplatin neo-adjuvant treatment was associated with a shorter DFS (p=0,0056) and poor OS (p=0,029). Our data reveal a paradoxical pro-metastatic effect of cisplatin that fosters MIC-IM recruitment and cross-talk via SDF-1/CXCR4 axis activation. A new combination strategy based on CXCR4 inhibition may disrupt these interactions, providing more effective and long-lasting results for lung cancer treatment