PO-215 Patient-derived and cell line xenograft growth in the B6;129-Rag2tm1FwaIL2rgtm1Rsky/DwlHsd (R2G2) mouse model

Abstract

Introduction Immunodeficient mouse models are helping to advance the field of oncology. A new model on the market, the B6;129-Rag2tm1FwaIL2rgtm1Rsky/DwlHsd (R2G2) knockout mouse, lacks responsiveness to common gamma chain cytokines, including IL-2, IL-4, IL-7, IL-9 and IL-15. In addition, this model exhibits defects in lymphoid development and so lacks mature lymphocytes of the B, T, and natural killer (NK) cell lineages. Herein we describe growth of multiple patient-derived (PDX) and tumour cell line xeno- (CDX) and allo-grafts in the R2G2 immunodeficient mouse model. Material and methods The PDXs examined include colorectal and head and neck cancers. The CDXs studied include esophageal (OE33 and FLO1) and stomach cancer (AGS). Tumour growth data was also collected from two allografts of murine colorectal cancer (CT26) and B-cell lymphoma (A20) cells. Results and discussions Colorectal PDX tissue was comparable between the R2G2 and the NSG mouse models, however the standard error was much lower in the R2G2 strain. Head and neck PDX 626 and 635 was transplanted in into 4 sections of R2G2 mice each, and 100% of mice developed either one or two tumours. The human esophageal adenocarcinoma OE33 cells were implanted into both flanks of R2G2, Athymic Nude and SCID mice. There was a 100% take rate in R2G2 mice, 0% in SCID mice and 17% in Athymic Nude mice. The human esophageal adenocarcinoma FLO1 cells were examined in two studies. In both studies, cells were injected into both flanks of R2G2 and SCID mice. Study A also examined growth in Athymic Nude mice. In study A, no tumour growth was seen in Athymic Nude or SCID mice, whereas the take rate was 100% in R2G2 mice. In study B, the take rate was 100% in both the R2G2 and the SCID mice, although differences were seen in growth rate. Human gastric adenocarcinoma AGS cells were implanted in both flanks of R2G2 and SCID mice. The take rate was 75% in R2G2 mice and 0% in SCID mice. Head and neck squamous cell carcinoma SQ20b cells were implanted in R2G2 mice and take rate was 90%. Growth of two allogeneic tumour lines was also examined. The mouse colon carcinoma CT26 cells were implanted in R2G2 mice and took in 100% of the mice. Mouse B-cell lymphoma A20 cells were implanted in R2G2 mice and take rate was 100%. Both allografts grew to 1000mm3 by 13 days post implantation. Conclusion These data provide evidence that the R2G2 mouse model is a valuable tool for oncology programs including cell line tumour models research, with high take rates and quick growth of allogeneic models.