Endobronchial Ultrasound-Transbronchial Needle Injection Cisplatin Induces Cell Death and Alters PDL1 Expression in Non- Small Cell Lung Cancer

Abstract

Rationale Direct intratumoral delivery of cisplatin via endobronchial ultrasound-transbronchial needle injections (EBUS-TBNI) is a novel approach for treatment of advanced-stage non-small cell lung cancer (NSCLC), including in combination with immunotherapy. Prior studies have demonstrated high rates of response in the treated volume. While it is established that direct cell death may act as an effective immunoadjuvant, even sublethal doses of cisplatin may activate the immune response. Specifically, there is evidence that cisplatin may alter programmed death ligand-1 (PDL1) expression. As the combination of direct intratumoral cisplatin and immunotherapy continues to be evaluated, it is critical to determine the cellular impact of direct intratumoral cisplatin. Methods Under an IRB approved protocol, patients undergoing clinicallyindicated weekly treatments with EBUS-TBNI cisplatin consented to additional biopsies. Prior to delivery of cisplatin, needle aspiration was performed at each procedure. Cells were stained with UV blue to determine live/dead percentages and quantitated via flow cytometry. Cells were stained for PDL1 in the live and dead cell gates for each cell type. Isotype controls were performed for each antibody stain. Analysis was performed using FlowJo software. All statistical analyses were performed using STATA. P values less than or equal to 0.05 were considered statistically significant. Results Three patients completed 4 treatments with EBUS-TBNI cisplatin. One of these patients was on immunotherapy with a PDL1 checkpoint inhibitor (nivolumab). Treatment over 4 weeks resulted in a significant increase in cell death, with an average of a 27% increase in cell death (P=0.049). There was an increase in the percentage of CD45-/ CD66+ cells in both the live and dead gates (22%, P=0.046). For CD45-/CD326+ cells (representing tumor epithelial cells) in the dead gate, there was a 23% decrease in PDL1+ cells with treatment over four weeks. In the live gate, there was an average decrease of 12% in PDL1+ cells for the two patients who did not receive immunotherapy. For the patient on nivolumab, there was an increase in PDL1+ cells of 26%. Conclusion EBUS-TBNI cisplatin results in significant tumor cell death and an increase in CD45-/CD66+ cells, which may represent granulocytes related to an inflammatory response, or myeloid-derived suppressor cells. With ongoing treatment, live CD45-/CD326+ cells were increasingly PDL1 negative for patients not on immunotherapy. Interestingly, for the patient on nivolumab, there was an increase in live CD45-/CD326+ PDL1 positive cells. Further analysis with larger number of patients will be necessary to better characterize this response.