Volume 2 Supplement 1
What we learned from bench to bedside with the neuroblastoma targeting CD171-specific CAR
© Künkele et al. 2015
Published: 1 July 2015
Despite the therapeutic efficacy of chimeric antigen receptor (CAR) redirected T cell immunotherapy in leukemia and lymphoma patients, similar clinical responses in solid tumor patients is, to date, an unrealized objective. We developed a CAR specific for CD171, an antigen expressed in several solid tumors including neuroblastoma, the most common extracranial tumor in childhood with an overall survival of less than 50% in high-risk patients. Since CD171 is also expressed in healthy tissues, including cerebellum and kidney, we proved the safety of targeting CD171 with CAR T cells in a non-human primate study. Further, we showed that CAR extracellular spacer and cytoplasmic signaling domain variants can be combined to tune the magnitude of cytotoxic CD8+ T lymphocyte (CTL) activation for tumor cell cytolysis and cytokine secretion. CAR constructs displaying the highest in vitro activity unexpectedly displayed the lowest in vivo anti-tumor activity, whereas CARs tuned for moderate signaling potency mediated tumor eradication. Recursively triggering hyperactive CARs rendered CTLs highly susceptible to activation-induced cell death resulting from augmented FasL expression, indicating that activation-induced cell death may be a critical parameter for achieving clinical efficacy against solid tumors. Our preclinical results assisted the design of a clinical trial comparing two CARs with different cytoplasmic signaling domains in patients with primary refractory or relapsed neuroblastoma, which was launched October 2014 at the Seattle Children's Hospital.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.