University of Michigan Ann arbor, MI, United States
Eileen Carpenter, MD, PhD1, Samantha Kemp, PhD2, Padma Kadiyala, 1, Nina Steele, PhD1, Ahmed Elhossiny, 1, Veerin Sirihorachai, 1, Wenting Du, PhD1, Carlos Espinoza, MA1, Stephanie The, MA1, Julia Freeman, 1, Sean Bhalla, MD1, Ajay Singhvi, MD1, Michelle Anderson, MD, MSc1, Richard Kwon, MD1, Erik-Jan Wamsteker, MD1, Anoop Prabhu, MD1, Allison Schulman, MD1, Valerie Gunchick, MA1, Vaibhav Sahai, MD1, Timothy Frankel, MD1, Filip Bednar, MD, PhD1, Marina Pasca Di Magliano, PhD1 1University of Michigan, Ann Arbor, MI; 2University of Pennsylvania, Philadelphia, PA
Introduction: Pancreatic ductal adenocarcinoma (PDAC) is the 4th leading cause of cancer-related death in the US. Although pancreatic cancer cells show susceptibility to standard chemotherapeutic agents, most patients eventually develop resistance, leading to poor survival.There is thus an urgent need to understand how pancreatic cancer cells become resistant to standard therapies. A large body of work using murine models implicate the myeloid compartment of the immune microenvironment playing a role in therapy resistance, yet longitudinal human studies remain scarce. To study the effect of chemotherapy on the systemic immune response of PDAC patients, we performed high resolution immune profiling of 30 PDAC patients longitudinally over the course of their treatment.
Methods: Patients were consented according to IRB HUM00025339 for longitudinal blood collection. Peripheral blood mononuclear cells (PBMCs) were isolated from blood and profiled using single cell RNA sequencing and mass cytometry with a custom tailored immune panel to profile the immune landscape at the single-cell RNA and protein level, respectively. Data were analyzed using the Seurat pipeline and the Cytobank platform.
Results: We performed mass cytometry on longitudinally matched PBMCs from 30 patients and single cell RNA sequencing on 6 patients in the treatment naïve and on treatment state. Mass cytometry revealed distinct alterations in the myeloid population, with a shift toward CXCR2hiPD-L1hi granulocytes with FOLFIRINOX treatment over time (Fig1A). Analysis of PBMCs at the single cell level shows a distinct myeloid signature with FOLFIRINOX and in particular highlights interleukin-8, a chemokine involved in myeloid cell chemotaxis that is associated with poor prognosis in pancreatic cancer (Fig1B).
Discussion: Longitudinal sampling of patient blood reveals a shift in the immunosuppressive myeloid population with chemotherapy, and further studies show a myeloid signature of genes associated with treatment. Going forward, we will extend our pipeline to include analysis of tumor tissue before and after chemotherapy, leveraging endoscopic fine needle biopsies both at initial tissue diagnosis and again after chemotherapy at fiducial marker placement for patients in whom radiation treatment is indicated. These studies will allow for a rigorous study of the changes in the local and systemic immune system that characterize this deadly disease, and will provide information on how to leverage these changes to overcome therapy resistance.
Figure: Fib 1A) tSNE analysis on representative matched peripheral blood of 3 patients before treatment and after 10 months of FOLFIRINOX therapy. Fig 1B) Unbiased differential expression in peripheral myeloid cells in treatment naive (TI) and on-treatment (T2) PDAC patient blood. Significantly up- and down-regulated genes are plotted as average expression per patient. Purple arrows denote interleukin-8 and its receptor, CXCR2.
Eileen Carpenter indicated no relevant financial relationships.
Samantha Kemp indicated no relevant financial relationships.
Padma Kadiyala indicated no relevant financial relationships.
Nina Steele indicated no relevant financial relationships.
Ahmed Elhossiny indicated no relevant financial relationships.
Veerin Sirihorachai indicated no relevant financial relationships.
Wenting Du indicated no relevant financial relationships.
Carlos Espinoza indicated no relevant financial relationships.
Stephanie The indicated no relevant financial relationships.
Julia Freeman indicated no relevant financial relationships.
Sean Bhalla indicated no relevant financial relationships.
Ajay Singhvi indicated no relevant financial relationships.