A Rational Strategy for Reducing On-Target Off-Tumor Effects of CD38-Chimeric Antigen Receptors by Affinity Optimization

Esther Drent, Maria Themeli, Renée Poels, Regina de Jong-Korlaar, Huipin Yuan, Joost de Bruijn, Anton C.M. Martens, Sonja Zweegman, Niels W.C.J. van de Donk, Richard W.J. Groen, Henk M. Lokhorst, Tuna Mutis*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Chimeric antigen receptors (CARs) can effectively redirect cytotoxic T cells toward highly expressed surface antigens on tumor cells. The low expression of several tumor-associated antigens (TAAs) on normal tissues, however, hinders their safe targeting by CAR T cells due to on-target/off-tumor effects. Using the multiple myeloma (MM)-associated CD38 antigen as a model system, here, we present a rational approach for effective and tumor-selective targeting of such TAAs. Using “light-chain exchange” technology, we combined the heavy chains of two high-affinity CD38 antibodies with 176 germline light chains and generated ∼124 new antibodies with 10- to >1,000-fold lower affinities to CD38. After categorizing them into three distinct affinity classes, we incorporated the single-chain variable fragments of eight antibodies from each class into new CARs. T cells carrying these CD38-CARs were extensively evaluated for their on-tumor/off-tumor cytotoxicity as well as CD38-dependent proliferation and cytokine production. We identified CD38-CAR T cells of ∼1,000- fold reduced affinity, which optimally proliferated, produced Th1-like cytokines, and effectively lysed CD382+ MM cells, but spared CD38+ healthy hematopoietic cells in vitro and in vivo. Thus, this systematic approach is highly suitable for the generation of optimal CARs for effective and selective targeting of TAAs.

Original languageEnglish
Pages (from-to)1946-1958
Number of pages13
JournalMolecular Therapy
Volume25
Issue number8
DOIs
Publication statusPublished - 2 Aug 2017

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