LAUSR

T cell receptor (TCR)–based therapy has the potential to induce durable clinical responses in patients with cancer by targeting intracellular tumor antigens with high sensitivity and by promoting T cell survival. However, the need for TCRs specific for shared oncogenic antigens and the need for manufacturing protocols able to redirect T cell specificity while preserving T cell fitness remain limiting factors. By longitudinal monitoring of T cell functionality and dynamics in 15 healthy donors, we isolated 19 TCRs specific for Wilms’ tumor antigen 1 (WT1), which is overexpressed by several tumor types. TCRs recognized several peptides restricted by common human leukocyte antigen (HLA) alleles and displayed a wide range of functional avidities. We selected five high-avidity HLA-A*02:01–restricted TCRs, three that were specific to the less explored immunodominant WT137–45 and two that were specific to the noncanonical WT1−78–64 epitopes, both naturally processed by primary acute myeloid leukemia (AML) blasts. With CRISPR-Cas9 genome editing tools, we combined TCR-targeted integration into the TCR α constant (TRAC) locus with TCR β constant (TRBC) knockout, thus avoiding TCRαβ mispairing and maximizing TCR expression and function. The engineered lymphocytes were enriched in memory stem T cells. A unique WT137–45-specific TCR showed antigen-specific responses and efficiently killed AML blasts, acute lymphoblastic leukemia blasts, and glioblastoma cells in vitro and in vivo in the absence of off-tumor toxicity. T cells engineered to express this receptor are being advanced into clinical development for AML immunotherapy and represent a candidate therapy for other WT1-expressing tumors. Description T cells engineered to express a high-avidity WT1-specific TCR and no competing endogenous TCRs can eliminate cancer cells in vitro and in vivo. Alternative WT1 targets Adoptive cell therapy using T cell receptor (TCR)–modified T cells has shown clinical success. However, it remains a challenge to find TCRs that respond to shared tumor antigens presented in common human leukocyte antigen molecules. To that end, Ruggiero et al. and Lahman et al. identified and tested TCR constructs targeting alternative epitopes in the Wilms’ tumor antigen 1 (WT1) protein. Ruggiero and colleagues identified WT137–45 as a candidate peptide for TCR-based therapies and used CRISPR-Cas9 editing to target WT137–45-specific TCR sequences to the TRAC locus. Lahman and colleagues showed that, whereas a TCR-targeted WT1 epitope was lost because of immunoproteasome down-regulation, WT137–45 retains its expression and could be targeted by T cells expressing TCRs specific to that epitope, even in cancer cells that lose immunoproteasome activity. In both cases, T cells expressing WT137–45-specific TCRs controlled tumor burden in murine models. Thus, WT137–45 represents a candidate target for TCR-based immunotherapies that is resistant to immunoproteasome down-regulation.