CD7-deleted hematopoietic stem cells can restore immunity after CAR T cell therapy
Miriam Y. Kim, Matthew L. Cooper, Miriam T. Jacobs, Julie K. Ritchey, Julia Hollaway, Todd A. Fehniger, John F. DiPersio
Miriam Y. Kim, Matthew L. Cooper, Miriam T. Jacobs, Julie K. Ritchey, Julia Hollaway, Todd A. Fehniger, John F. DiPersio
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Research Article Immunology Oncology

CD7-deleted hematopoietic stem cells can restore immunity after CAR T cell therapy

Abstract

Targeting T cell malignancies with universal CD7-targeting chimeric antigen receptor T cells (UCART7) can lead to profound immune deficiency due to loss of normal T and NK cells. While a small population of endogenous CD7– T cells exists, these cells are unlikely to be able to repopulate the entire immune repertoire after UCART7 treatment, as they are limited in number and proliferative capacity. To rescue T and NK cells after UCART7, we created hematopoietic stem cells genetically deleted for CD7 (CD7-KO HSCs). CD7-KO HSCs were able to engraft immunodeficient mice and differentiate into T and NK cells lacking CD7 expression. CD7-KO T and NK cells could perform effector functions as robustly as control T and NK cells. Furthermore, CD7-KO T cells were phenotypically and functionally distinct from endogenous CD7– T cells, indicating that CD7-KO T cells can supplement immune functions lacking in CD7– T cells. Mice engrafted with CD7-KO HSCs maintained T and NK cell numbers after UCART7 treatment, while these were significantly decreased in control mice. These studies support the development of CD7-KO HSCs to augment host immunity in patients with T cell malignancies after UCART7 treatment.

Authors

Miriam Y. Kim, Matthew L. Cooper, Miriam T. Jacobs, Julie K. Ritchey, Julia Hollaway, Todd A. Fehniger, John F. DiPersio

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Figure 3

CD7-KO T and NK cells remain functional.

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CD7-KO T and NK cells remain functional. (A and B) Human T cells in the ...
(A and B) Human T cells in the spleens of NSGS mice engrafted with control or CD7-KO HSCs were functionally interrogated in vitro. (A) Levels of pErk1/2 and pSTAT5 were assessed in control and CD7-KO T cells at baseline and in response PMA and IL-2 stimulation (n = 4 mice/group) (unpaired 2-tailed Student’s t test). (B) Degranulation (%CD107a) and intracellular cytokine production (%IL-2, IFN-γ, GM-CSF, TNF-α, MIP1b) in control and CD7-KO T cells was measured after stimulation with PMA and ionomycin. (n = 7 mice/group) (unpaired 2-tailed Student’s t test). (C and D) Human NK cells purified from the spleens of NSG–huIL-15 mice engrafted with control or CD7-KO HSCs were interrogated in vitro. (C) Control and CD7-KO NK cells were incubated at different E:T ratios with UM-SCC-9, a human squamous cell carcinoma cell line, and tumor cell numbers were serially measured over time using the Incucyte Live Cell Analysis system (data expressed as median range of triplicate wells) (2-way ANOVA with multiple comparisons). (D) Expression of CD16 and KIR was measured in control and CD7-KO NK cells. (E) Mice engrafted with control or CD7-KO HSCs were treated with NT-I7, a long-acting IL-7 agonist, s.c. every 2 weeks starting 1 week after HSC injection for 7 doses total (n = 7–8 mice/group). Numbers of peripheral blood human NK cells and T cells are shown at 4 weeks and 15 weeks, respectively, after HSC engraftment (1-way ANOVA with Holm-Sidak multiple-comparison test). *P < 0.05, **P < 0.01, ****P < 0.0001.