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

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 antitumor activity that can be reactivated using combination immunotherapy. EXPERIMENTAL DESIGN: Preserved human PDA specimens were analyzed using multiplex IHC (mIHC) 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: mIHC 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. CONCLUSIONS: 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.See related commentary by Medina and Miller, p. 3747.

Superior Patient and Graft Survival in Adult Liver Transplant with Rabbit Antithymocyte Globulin Induction: Experience with 595 Patients.

OBJECTIVES: The use of induction therapy in liver transplant is debatable. We aimed to compare clinical outcomes of different induction protocols in liver transplant recipients. MATERIALS AND METHODS: This was a retrospective cohort analyses using the University of Washington Transplant Database from January 2005 to May 2012 for adult (≥ 18 y old) primary liver transplant patients. All patients received induction therapy. Maintenance immunosuppressive agents were tacrolimus or tacrolimus-mycophenolate mofetil. Primary endpoints were acute cellular rejection, patient survival, and graft survival. In patients with chronic hepatitis C, the degree of histologic inflammation or fibrosis at 1 year was assessed. Cox proportional hazards models were constructed to evaluate variables associated with both patient and graft survival. RESULTS: We identified 595 patients: 322 patients received rabbit antithymocyte globulin and 273 received interleukin 2 receptor blocker. Acute cellular rejection was higher in patients who received interleukin 2 receptor blocker than in patients who received rabbit antithymocyte globulin (27% vs 18%; P < .03). Both patient survival at 1 year (95% vs 90%), 3 years (92% vs 87%), and 5 years (86% vs 80%) and graft survival at 1 year (93% vs 88%), 3 years (90% vs 86%), and 5 years (83% vs 78%) were superior with rabbit antithymocyte globulin than with the interleukin 2 receptor blocker (P < .002). In patients with hepatitis C virus, type of induction therapy did not have any effect on the timing of hepatitis C virus recurrence. At 1 year after transplant, 33.3% in the rabbit antithymocyte globulin group had grade 3/4 inflammation and 10.2% had stage 3/4 fibrosis, compared with 16.8% and 4.8% in the interleukin 2 receptor blocker group (P ≤ .002 and not significant). Female recipient, Model for End-Stage Liver Disease score, hepatocellular carcinoma, and high preoperative serum creatinine levels were associated with less favorable patient and graft survival. CONCLUSIONS: Rabbit antithymocyte globulin is associated with lower rejection rate and improved patient and graft survival in liver transplant. Type of therapy affects the degree of histologic hepatitis C virus recurrence.

Analysis of ROR1 Protein Expression in Human Cancer and Normal Tissues.

Purpose: This study examines cell surface ROR1 expression in human tumors and normal tissues. ROR1 is considered a promising target for cancer therapy due to putative tumor-specific expression, and multiple groups are developing antibodies and/or chimeric antigen receptor-modified T cells to target ROR1. On-target, off-tumor toxicity is a challenge for most nonmutated tumor antigens; however, prior studies suggest that ROR1 is absent on most normal tissues.Experimental Design: Our studies show that published antibodies lack sensitivity to detect endogenous levels of cell surface ROR1 by immunohistochemistry (IHC) in formalin-fixed, paraffin-embedded tissues. We developed a ROR1-specific monoclonal antibody (mAb) targeting the carboxy-terminus of ROR1 and evaluated its specificity and sensitivity in IHC.Results: The 6D4 mAb is a sensitive and specific reagent to detect cell surface ROR1 by IHC. The data show that ROR1 is homogenously expressed on a subset of ovarian cancer, triple-negative breast cancer, and lung adenocarcinomas. Contrary to previous findings, we found ROR1 is expressed on several normal tissues, including parathyroid; pancreatic islets; and regions of the esophagus, stomach, and duodenum. The 6D4 mAb recognizes rhesus ROR1, and ROR1 expression was similar in human and macaque tissues, suggesting that the macaque is a suitable model to evaluate safety of ROR1-targeted therapies.Conclusions: ROR1 is a promising immunotherapeutic target in many epithelial tumors; however, high cell surface ROR1 expression in multiple normal tissues raises concerns for on-target off-tumor toxicities. Clinical translation of ROR1-targeted therapies warrants careful monitoring of toxicities to normal organs and may require strategies to ensure patient safety. Clin Cancer Res; 23(12); 3061-71. ©2016 AACR.

CT of Atypical and Uncommon Presentations of Hepatocellular Carcinoma.

OBJECTIVE: The purpose of this article is to familiarize radiologists with uncommon presentations of hepatocellular carcinoma (HCC) with an emphasis on the CT spectrum of atypical appearances. CONCLUSION: HCC is the fifth most common neoplasm worldwide and the second most common cause of cancer-related death. In many cases, HCC can be confidently diagnosed with noninvasive imaging. However, there are numerous unusual appearances of HCC with which the radiologist must be familiar.