Microsatellite instability-high colorectal cancer patient-derived xenograft models for cancer immunity research
Hirotaka Suto1, Yohei Funakoshi1, Yoshiaki Nagatani1, Yoshinori Imamura1, Masanori Toyoda1, Naomi Kiyota2, Hisayuki Matsumoto3, Shinwa Tanaka4, Ryo Takai5, Hiroshi Hasegawa5, Kimihiro Yamashita5, Takeru Matsuda5, Yoshihiro Kakeji5, Hironobu Minami2
1 Department of Medicine, Division of Medical Oncology/Hematology, Kobe University Hospital and Graduate School of Medicine, Kobe, Japan
2 Department of Medicine, Division of Medical Oncology/Hematology, Kobe University Hospital and Graduate School of Medicine; Cancer Center, Kobe University Hospital, Kobe, Japan
3 Department of Clinical Laboratory, Kobe University Hospital, Kobe, Japan
4 Department of Medicine, Division of Gastroenterology, Kobe University Hospital and Graduate School of Medicine, Kobe, Japan
5 Department of Surgery, Division of Gastrointestinal Surgery, Kobe University Hospital and Graduate School of Medicine, Chuo-ku, Kobe, Japan
Department of Medicine, Division of Medical Oncology/Hematology, Kobe University Hospital and Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017
Source of Support: None, Conflict of Interest: None
Context: There is an increasing demand for appropriate preclinical mice models for evaluating the efficacy of cancer immunotherapies.
Aims: Therefore, we established a humanized patient-derived xenograft (PDX) model using microsatellite instability-high (MSI-H) colorectal cancer (CRC) tissues and patient-derived peripheral blood mononuclear cells (PBMCs).
Subjects and Methods: The CRC tissues of patients scheduled for surgery were tested for MSI status, and CRC tumors were transplanted into NOD/LtSz-scid/IL-2Rg-/-(NSG) mice to establish MSI-H PDX models. PDX tumors were compared to the original patient tumors in terms of histological and genetic characteristics. To humanize the immune system of MSI-H PDX models, patient PBMCs were injected through the tail vein.
Results: PDX models were established from two patients with MSI-H CRC; one patient had a germline mutation in MLH1 (c.1990-2A > G), and the other patient had MLH1 promoter hypermethylation. PDX with the germline mutation was histologically similar to the patient tumor, and retained the genetic characteristics, including MSI-H, deficient mismatch repair (dMMR), and MLH1 mutation. In contrast, the histological features of the other PDX from a tumor with MLH1 promoter hypermethylation were clearly different from those of the original tumor, and MLH1 promoter hypermethylation and MSI-H/dMMR were lost in the PDX. When T cells from the same patient with MLH1 mutation were injected into the PDX through the tail vein, they were detected in the PDX tumor.
Conclusions: The MSI-H tumor with an MMR mutation is suitable for MSI-H PDX model generation. The PBMC humanized MSI-H PDX has the potential to be used as an efficient model for cancer immunotherapy research.