In Vivo Expansion and Antitumor Activity of Coinfused CD28- and 4-1BB-Engineered CAR-T Cells in Patients with B Cell Leukemia

Abstract

Several recent clinical trials have successfully incorporated a costimulatory domain derived from either CD28 or 4-1BB with the original CD3ζ T cell activating domain to form second-generation chimeric antigen receptors (CARs) that can increase the responsiveness and survival of CAR-engineered T (CAR-T) cells. However, a rigorous assessment of the individual benefits of these costimulatory components relative to the in vivo performance of infused T cells in patients is still lacking. Therefore, we have designed a study that allows us to investigate and compare the impact of different costimulatory signal domains on CAR-T cells in vivo. Patients with B cell leukemia were infused with a mixture of two types of CD19-specific CAR-T cells, individually bearing CD28 (28ζ) and 4-1BB (BBζ) costimulatory signaling domains. We found that such a clinical procedure was feasible and safe. Complete remission (CR) was observed in five of seven enrolled patients, with two patients exhibiting durable CR lasting more than 15 months. The in vivo expansion pattern of 28ζ and BBζ CAR-T cells varied significantly among individual patients. These results confirm a feasible method of comparing different CAR designs within individual patients, potentially offering objective insights that may facilitate the development of optimal CAR-T cell-based immunotherapies.

Selecting costimulatory domains for chimeric antigen receptors: functional and clinical considerations

“…27 Clinical data also indicate that third-generation CARs lead to improved CAR T cell expansion and persistence. Considering the results of Cheng et al, 25 who reported no significant difference between two-second-generation (CD28 vs 4-1BB) CAR T cells co-infused in patients, Ramos et al 56 concluded that third-generation CAR T cell therapy may be effective in the eradication of minimal residual disease and lead to longer, more durable remissions. One case of severe cytokine release syndrome (CRS) and one case of severe CAR T cell-related encephalopathy syndrome (CRES), also referred to as immune effector cell-associated neurotoxicity syndrome (ICANS), were observed.…”

“…Moreover, only third-generation CAR T cells expanded significantly when infused to patients in remission after autologous stem cell transplantation, suggesting the third-generation CAR T cells can expand despite minimal CD19 antigen exposure. 25,27 Enblad et al 58 reported the outcomes of 15 patients with r/r B-cell malignancies treated with autologous anti-CD19 CAR T cells incorporating both CD28 and 4-1BB costimulatory domains, four of whom did not receive lymphodepletion before CAR T cell infusion.…”

“…21 Human CD8 + CD28costimulated CAR T cells have shown both central and effector memory phenotypes and exhibit rapid proliferation and IFN-c production in vitro upon recognition of target antigen. [22][23][24][25] Recruitment of regulatory T cells by CD28costimulated CAR T cell-derived IL-2 may limit antitumor activity in some models. 26 However, in general, T cells expressing second-generation CARs with CD28 costimulatory domains are associated with faster tumor elimination and activity at lower effector:target ratios compared to those expressing CARs with 4-1BB domains.…”

“…Moreover, only third-generation CAR T cells expanded significantly when infused to patients in remission after autologous stem cell transplantation, suggesting the third-generation CAR T cells can expand despite minimal CD19 antigen exposure. Considering the results of Cheng et al, 25 who reported no significant difference between two-second-generation (CD28 vs 4-1BB) CAR T cells co-infused in patients, Ramos et al 56 concluded that third-generation CAR T cell therapy may be effective in the eradication of minimal residual disease and lead to longer, more durable remissions. Enblad et al 58 reported the outcomes of 15 patients with r/r B-cell malignancies treated with autologous anti-CD19 CAR T cells incorporating both CD28 and 4-1BB costimulatory domains, four of whom did not receive lymphodepletion before CAR T cell infusion.…”

Improving the safety of CAR-T cell therapy by controlling CRS-related coagulopathy

“…In CD19-positive B cell malignancies, approximately 90% acute lymphoblastic leukemia (ALL) patients [1][2][3][4][5][6][7][8][9][10][11][12] and 70% lymphoma patients [13][14][15][16][17][18] can get remissions through CD19-specific CAR-T therapy. Encouragingly, two of the CD19-targeted CAR-T therapies, Kymriah and Yescarta, have been approved to treat relapsed/refractory (r/r) pediatric, young adult B cell ALL (B-ALL), and certain adult non-Hodgkin lymphomas (NHL) by the US Food and Drug Administration in 2017.…”