Description

Feasibility of isolating tumor-reactive T cells from peripheral blood of colorectal cancer patients by co-culture with autologous tumor organoids

K. Dijkstra, C. Cattaneo, F. Weeber, L. Fanchi, D. van der Velden, S. Kelderman, S. Kaing, N. van Rooij, T. Schumacher, E. Voest

The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, The Netherlands

Adoptive transfer of tumor-infiltrating lymphocytes (TIL) has shown impressive clinical success in the treatment of melanoma, but has thus far been unsuccessful for colorectal cancer (CRC). The lack of success of TIL therapy in CRC may be explained by both the limited availability of tumor material for TIL isolation, and the poor proliferative potential of the tumor-specific T cells within such material. Peripheral blood provides a potentially attractive alternative source of tumor-reactive T cells for adoptive transfer, provided that these cells can be selectively expanded. The recent success of establishing individual tumor organoid cultures - even from limited tissue – provides a potential strategy towards this goal.

To test this hypothesis, we generated organoids from patients with microsatellite instable (MSI) CRC and co-cultured these with autologous PBMC. In two out of eight patients (25%) for which MHC-I-proficient tumor organoids were available, a clear CD8⁺ T cell response was induced after two weeks of co-culture, ranging from 7-40% IFNγ⁺ and/or CD107a⁺ CD8⁺ T cells. Tumor reactivity was undetectable or present at a lower magnitude in PBMC directly ex vivo (0-14%), indicating that co-culture with autologous organoids induces or expands a tumor-reactive T cell population.

Live imaging showed that for one of these patients, co-cultured PBMC effectively killed autologous but not allogeneic tumor organoids. Organoids from the other patient, however, were resistant to killing by the co-cultured PBMC. Upon transduction with the MART-1 antigen, these organoids were effectively killed by MART-1-specific T cells, indicating that these organoids are not intrinsically resistant to T cell killing.

Taken together, these data provide proof of concept that tumor organoids can be used to obtain tumor-reactive T cell products from peripheral blood. The high success rate of establishing tumor organoid lines for individual patients provides a potential avenue for individualized T cell therapy. In addition, this platform may allow the testing of the role of different inhibitory mechanisms on tumor cell recognition by T cells in CRC.