Abstract 2799: Adoptive immunotherapy for pediatric solid tumors with CAR-T cells (chimeric antigen receptor bearing T cells) targeting ALK (anaplastic lymphoma kinase, CD246)

• Published in: Cancer research (Chicago, Ill.) Ill.), 2014-10, Vol.74 (19_Supplement), p.2799-2799
• Main Authors: Walker, Alec, Lopomo, Paola, Babbitt, William, Vigny, Marc, Mackall, Crystal L., Orentas, Rimas J.
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2014-2799

Neuroblastoma is the most common non-CNS tumor in children. High-risk disease has a dire prognosis and new treatment strategies are need. The identification of unique cell-surface proteins expressed on tumor cells, yet not expressed on normal tissues, has been challenging for pediatric malignancies. However, identification of such antigens allows for the development of new immune-based therapies featuring Ig-like binding motifs. The cell surface tyrosine kinase ALK (CD246, anaplastic lymphoma kinase) is a promising target for neuroblastoma in that it is expressed in either native, mutated, or over-expressed forms on the plasma membrane surface of the tumor cell and may contribute to disease progression or severity. We identified antibodies that bind to extracellular domains of ALK, sequenced their variable regions, and used this sequence information to construct chimeric antigen receptors (CARs). Primary human T lymphocytes were then transduced with retroviral gene vectors expressing a series of ALK-specific CAR. We tested CARs that incorporated both different structural and signaling motifs. Transduced T cells demonstrated ALK-specific cytolytic activity against ALK-expressing tumors and produced Th1 cytokines upon culture in the presence of tumor. In exploring different iterations of CAR domain structure we found that the scFv domains created from the heavy and light variable domains of ALK-specific immunoglobulin could be interchanged with respect to their orientation in the context of CAR tertiary protein structure. Moreover, ALK-specific scFv functioned whether expressed in a short format, that is as a single domain proximal to the T cell membrane, or in a long format, that is extended away from the plasma membrane using an IgG1-derived spacer domain composed of CH2 and CH3. Using a xenogeneic NSG mouse model for neuroblastoma, human ALK-specific CAR-expressing T cells were found to eradicate ALK-positive tumor, when IL-7 was included to support T cell persistence. These data argue for the continued evaluation of ALK-specific CARs in pre-clinical studies. Citation Format: Alec Walker, Paola Lopomo, William Babbitt, Marc Vigny, Crystal L. Mackall, Rimas J. Orentas. Adoptive immunotherapy for pediatric solid tumors with CAR-T cells (chimeric antigen receptor bearing T cells) targeting ALK (anaplastic lymphoma kinase, CD246). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego,