Choice of costimulatory domains and of cytokines determines CAR T-cell activity in neuroblastoma

• Published in: Oncoimmunology 2018-06, Vol.7 (6), p.e1433518-e1433518
• Main Authors: Quintarelli, Concetta, Orlando, Domenico, Boffa, Iolanda, Guercio, Marika, Polito, Vinicia Assunta, Petretto, Andrea, Lavarello, Chiara, Sinibaldi, Matilde, Weber, Gerrit, Del Bufalo, Francesca, Giorda, Ezio, Scarsella, Marco, Petrini, Stefania, Pagliara, Daria, Locatelli, Franco, De Angelis, Biagio, Caruana, Ignazio
• Format: Article
• Language: English
• Subjects: CAR.GD2 design; CD28.4-1BB costimulatory domains; Chimeric antigen receptor (CAR); Neuroblastoma; Original Research; solid tumors; T-cell exhaustion
• ISSN: 2162-4011; 2162-402X; 2162-402X
• DOI: 10.1080/2162402X.2018.1433518

Chimeric antigen receptor (CAR) T-cell therapy has been shown to be dramatically effective in the treatment of B-cell malignancies. However, there are still substantial obstacles to overcome, before similar responses can be achieved in patients with solid tumors. We evaluated both in vitro and in a preclinical murine model the efficacy of different 2nd and 3rd generation CAR constructs targeting GD2, a disial-ganglioside expressed on the surface of neuroblastoma (NB) tumor cells. In order to address potential safety concerns regarding clinical application, an inducible safety switch, namely inducible Caspase-9 (iC9), was also included in the vector constructs. Our data indicate that a 3rd generation CAR incorporating CD28.4-1BB costimulatory domains is associated with improved anti-tumor efficacy as compared with a CAR incorporating the combination of CD28.OX40 domains. We demonstrate that the choice of 4-1BB signaling results into significant amelioration of several CAR T-cell characteristics, including: 1) T-cell exhaustion, 2) basal T-cell activation, 3) in vivo tumor control and 4) T-cell persistence. The fine-tuning of T-cell culture conditions obtained using IL7 and IL15 was found to be synergic with the CAR.GD2 design in increasing the anti-tumor activity of CAR T cells. We also demonstrate that activation of the suicide gene iC9, included in our construct without significantly impairing neither CAR expression nor anti-tumor activity, leads to a prompt induction of apoptosis of GD2.CAR T cells. Altogether, these findings are instrumental in optimizing the function of CAR T-cell products to be employed in the treatment of children with NB.