Natural killer cells and cytotoxic T lymphocytes are required to clear solid tumor in a patient-derived xenograft
Duy Tri Le, Tridu R. Huynh, Bryan Burt, George Van Buren, Shawn A. Abeynaike, Cristina Zalfa, Rana Nikzad, Farrah Kheradmand, John J. Tyner, Silke Paust
Duy Tri Le, Tridu R. Huynh, Bryan Burt, George Van Buren, Shawn A. Abeynaike, Cristina Zalfa, Rana Nikzad, Farrah Kheradmand, John J. Tyner, Silke Paust
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Resource and Technical Advance Immunology

Natural killer cells and cytotoxic T lymphocytes are required to clear solid tumor in a patient-derived xenograft

Abstract

Existing patient-derived xenograft (PDX) mouse models of solid tumors lack a fully tumor donor–matched, syngeneic, and functional immune system. We developed a model that overcomes these limitations by engrafting lymphopenic recipient mice with a fresh, undisrupted piece of solid tumor, whereby tumor-infiltrating lymphocytes (TILs) persisted in the recipient mice for several weeks. Successful tumor engraftment was achieved in 83% to 89% of TIL-PDX mice, and these were seen to harbor exhausted immuno-effector as well as functional immunoregulatory cells persisting for at least 6 months postengraftment. Combined treatment with interleukin-15 stimulation and immune checkpoint inhibition resulted in complete or partial tumor response in this model. Further, depletion of cytotoxic T lymphocytes and/or natural killer cells before combined immunotherapy revealed that both cell types were required for maximal tumor regression. Our TIL-PDX model provides a valuable resource for powerful mechanistic and therapeutic studies in solid tumors.

Authors

Duy Tri Le, Tridu R. Huynh, Bryan Burt, George Van Buren, Shawn A. Abeynaike, Cristina Zalfa, Rana Nikzad, Farrah Kheradmand, John J. Tyner, Silke Paust

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Figure 2

Human immune cells persist for months in TIL-PDX-LUAD mice.

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Human immune cells persist for months in TIL-PDX-LUAD mice. (A) Generati...
(A) Generation of the TIL-PDX model of human LUAD in NSG mice: human lung adenocarcinoma freshly dissected from lobectomy, single 2 to 3 mm3 piece of undisrupted tumor inserted into the subcutaneous space of an NSG mouse flank, simple interrupted sutures or surgical clips used to close the incision site, and vascularized tumor as early as 6 weeks postimplantation. (B) Representative H&E staining at 10× and associated 40× magnifications of human donor LUAD and TIL-PDX–excised LUAD demonstrating preserved carcinoma architecture. (C) Top: 7-color IHC stain (DAPI, CD4, CD8, Foxp3, CD20, CD68, pan-cytokeratin) of a patient’s original tumor prior to implant. Bottom: CD3, NKp46, DAPI IHC stain of a patient’s original tumor prior to implant. (D–I) Flow cytometry of human immune cells from PBMC of TIL-PDX-LUAD mice, 1 month, 2 months, or 5–6 months posttransplant. Percentage of (D) human hematopoietic cells (human CD45+) of total (mouse CD45+ + human CD45+) hematopoietic cells; (E) NK cells (CD45+CD3–CD56+); (F) conventional T cells (CD45+CD3+CD56–), including (G) CTLs (CD45+CD3+CD4–CD8+CD56–) and (H) T helper (CD45+CD3+CD4+CD8–CD56–) subsets; and (I) NK T cells at indicated times posttransplant. Scale bars: 800 μm for main panels, 100 μm for insets (B); 200 μm (C). D–I: Six genetically unrelated donor cohorts were analyzed 1 and 2 months after transplantation. Depending on cohort size, 3 to 7 TIL-PDX-LUAD mice were analyzed from each donor cohort at each time point resulting in n = 15 to 42 data points per cell type and time point. As our IACUC requires euthanasia of PDX mice whose tumors reach a specified tumor size, we analyzed 4 unrelated donor cohorts 6 months after transplantation. Depending on cohort size, 5 to 9 TIL-PDX-LUAD mice were analyzed per cohort, resulting in 23 to 39 data points per cell type. Data are represented as mean ± SEM; 1-way ANOVA with post hoc Tukey’s test. *P < 0.05; **P < 0.01; ***P < 0.001.