Adoptive transfer of immune effector cells that are gene modified by retroviral transduction to express tumor-specific receptors constitutes an attractive approach to treat cancer. In patients with metastatic renal cell carcinoma, we performed a study with autologous T cells genetically retargeted with a chimeric antibody receptor (CAR) directed toward carbonic anhydrase IX (CAIX), an antigen highly expressed in renal cell carcinoma. In the majority of patients, we observed distinct humoral and/or cellular anti-CAIX-CAR T-cell immune responses in combination with a limited peripheral persistence of transferred CAIX-CAR T cells in the majority of patients. Humoral immune responses were anti-idiotypic in nature and neutralized CAIX-CAR-mediated T-cell function. Cellular anti-CAIX-CAR immune responses were directed to the complementarity-determining and framework regions of the CAR variable domains. In addition, 2 patients developed immunity directed against presumed retroviral vector epitopes. Here, we document the novel feature that therapeutic cells, which were ex vivo engineered by means of transduction with a minimal γ-retroviral vector, do express immunogenic vector-encoded epitopes, which might compromise persistence of these cells. These observations may constitute a critical concern for clinical ex vivo γ-retroviral gene transduction in general and CAR-retargeted T-cell therapy in particular, and underscore the need to attenuate the immunogenicity of both transgene and vector.

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Persistent URL dx.doi.org/10.1182/blood-2010-07-294520, hdl.handle.net/1765/33545
Citation
Lamers, C.H.J., Willemsen, R.A., van Elzakker, P.M.M.L., van Steenbergen-Langeveld, S., Broertjes, M., Oosterwijk-Wakka, J., … Gratama, J.W.. (2011). Immune responses to transgene and retroviral vector in patients treated with ex vivo-engineered T cells. Blood, 117(1), 72–82. doi:10.1182/blood-2010-07-294520