Humanized mice in studying efficacy and mechanisms of PD-1-targeted cancer immunotherapy

Abstract

Establishment of an in vivo small animal model of human tumor and human immune system interaction would enable preclinical investigations into themechanisms underlying cancer immunotherapy. To this end, nonobese diabetic (NOD).Cg-PrkdcscidIL2rgtm1Wjl/Sz (null; NSG) mice were transplanted with human (h)CD34+ hematopoietic progenitor and stem cells, which leads to the development of human hematopoietic and immune systems [humanized NSG (HuNSG)]. HuNSG mice received human leukocyte antigen partially matched tumor implants from patientderived xenografts [PDX;non-small cell lungcancer (NSCLC), sarcoma, bladder cancer, andtriple-negative breast cancer (TNBC)] or from a TNBC cell line-derived xenograft (CDX). Tumor growth curves were similar in HuNSG compared with nonhuman immune-engrafted NSGmice. Treatmentwith pembrolizumab, which targets programmed cell death protein 1, produced significant growth inhibition inbothCDXandPDXtumorsinHuNSGbut not inNSGmice. Finally, inhibition of tumor growth was dependent on hCD8+ T cells, as demonstrated by antibody-mediated depletion. Thus, tumor-bearingHuNSG mice may represent an important, newmodel for preclinical immunotherapy research.