Mobilization of CD8+ T Cells via CXCR4 Blockade Facilitates PD-1 Checkpoint Therapy in Human Pancreatic Cancer

Abstract

Purpose: Pancreatic ductal adenocarcinoma (PDA) is rarely cured, and single-agent immune checkpoint inhibition has not demonstrated clinical benefit despite the presence of large numbers of CD8+ T cells. We hypothesized that tumor-infiltrating CD8+ T cells harbor latent anti-tumor activity that can be reactivated using combination immunotherapy. Experimental Design: Preserved human PDA specimens were analyzed using multiplex immunohistochemistry (IHC) and T cell receptor (TCR) sequencing. Fresh tumor was treated in organotypic slice culture to test the effects of combination PD-1 and CXCR4 blockade. Slices were analyzed using IHC, flow cytometry and live fluorescent microscopy to assess tumor kill, in addition to T cell expansion and mobilization. Results: Multiplex IHC demonstrated fewer CD8+ T cells in juxtatumoral stroma containing carcinoma cells than in stroma devoid of them. Using TCR sequencing, we found clonal expansion in each tumor; high frequency clones had multiple DNA rearrangements coding for the same amino acid binding sequence, which suggests response to common tumor antigens. Treatment of fresh human PDA slices with combination PD-1 and CXCR4 blockade led to increased tumor cell death concomitant with lymphocyte expansion. Live microscopy after combination therapy demonstrated CD8+ T cell migration into the juxtatumoral compartment and rapid increase in tumor cell apoptosis. Conclusion: Endogenous tumor-reactive T cells are present within the human PDA tumor microenvironment and can be reactivated by combined blockade of PD-1 and CXCR4. This provides a new basis for the rational selection of combination immunotherapy for PDA.

Immunotherapy in Renal Cell Carcinoma: The Future Is Now

“…Already used for TKI targeted therapies, these models are increasingly being considered as potential platforms for monitoring immunotherapy responses [89]. Recent studies indeed reported an active immune TME after applying immunomodulatory molecules on tumour slice organotypic cultures, opening the way for their study on 3D ex vivo tumour models [90]. Interestingly, co-cultures of tumour-derived organoids were enriched with lymphocytes, leading Dijkstra and collaborators to recently demonstrate the generation of tumour-reactive T cells by co-culture of peripheral blood lymphocytes and colorectal cancer-derived organoids [91].…”

Multiplexed drug testing of tumor slices using a microfluidic platform

“…An additional caveat of the xenograft slice cultures is that a human tumor grows in a non-native mouse microenvironment. Studies with tissue that retains the native microenvironment may also facilitate the testing of newer agents, such as shown in slice culture for immune check-point inhibitors 14,42 and adenovirus-based therapies 43 , alone or in combination with conventional targeted or genotoxic drugs. For example, Seo et al recently demonstrated a response to immunotherapy with combined PD-1 and CXCR4 blockade in human pancreatic cancer slices 42 .…”

“…Studies with tissue that retains the native microenvironment may also facilitate the testing of newer agents, such as shown in slice culture for immune check-point inhibitors 14,42 and adenovirus-based therapies 43 , alone or in combination with conventional targeted or genotoxic drugs. For example, Seo et al recently demonstrated a response to immunotherapy with combined PD-1 and CXCR4 blockade in human pancreatic cancer slices 42 . The use of patient tumor tissue will permit studies with a native human microenvironment, and complementary studies in the future with syngeneic or transgenic mouse tumor models could exploit the intact mouse microenvironment.…”

PD-1 Expression by Lymph Node and Intratumoral Regulatory T Cells Is Associated with Lymph Node Metastasis in Pancreatic Cancer

“…Agonist anti-CD40 therapy with chemotherapy reversed the complete resistance of murine pancreatic tumors to PD-1 and CTLA-4 blockade [ 36 ]. Endogenous tumor-reactive T cells are present within the human PDAC tumor microenvironment and can be reactivated by combined blockade of PD-1 and C-X-C chemokine receptor 4 (CXCR4) [ 37 ]. These preclinical observations argue against the currently accepted paradigm that PDAC does not respond to immunotherapy due to a lack of immunogenicity or generation of tumor-reactive T cells.…”