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Cell Therapy & Immunotherapy
CD38 knockout natural killer cells expressing an affinity optimized CD38 chimeric antigen receptor successfully target acute myeloid leukemia with reduced effector cell fratricide
Mark Gurney,1 Arwen Stikvoort,2 Emma Nolan,1 Lucy Kirkham-McCarthy,1 Stanislav Khoruzhenko,3 Rama Shivakumar,3 Sonja Zweegman,2 Niels W.C.J. van de Donk,2 Tuna Mutis,2 Eva Szegezdi,1 Subhashis Sarkar1# and Michael O’Dwyer1#
1National University of Ireland Galway, Galway, Ireland; 2Cancer Center Amsterdam, VU University Medical Center, Amsterdam, the Netherlands and 3MaxCyte, Inc., Gaithersburg, MD, USA
#SS and MOD contributed equally as co-senior authors.
ABSTRACT
There is a strong biological rationale for the augmentation of allo- geneic natural killer (NK) cell therapies with a chimeric antigen receptor (CAR) to enhance acute myeloid leukemia (AML) target- ing. CD38 is an established immunotherapeutic target in multiple myeloma and under investigation as a target antigen in AML. CD38 expression on NK cells and its further induction during ex vivo NK cell expansion represent barriers to the development of a CD38 CAR-NK cell therapy. We set out to develop a CD38 CAR-NK cell therapy for AML, first by using an NK cell line which has low baseline CD38 expression and subsequently NK cells expanded from healthy donors. To overcome anticipated fratricide due to NK cell CD38 expression when using pri- mary expanded NK cells, we applied CRISPR/Cas9 genome editing to disrupt the CD38 gene during expansion, achieving a mean knockdown efficiency of 84%. The resulting CD38 knockdown expanded NK cells, after expression of an affinity optimized CD38 CAR, showed reduced NK-cell fratricide and an enhanced ability to target primary AML blasts. Furthermore, the cytotoxic potential of CD38 CAR-NK cells was aug- mented by pretreatment of the AML cells with all-trans retinoic acid which drove enhanced CD38 expression, offering a rational combination therapy. These findings support the further investigation of CD38 knockdown - CD38 CAR-NK cells as a viable immunotherapeutic approach to the treatment of AML.
Introduction
Acute myeloid leukemia (AML) is the most common acute leukemia in adults, accounting for approximately 2% of all cancer deaths.1 Curative treatment approaches remain chemotherapy-based, with allogeneic stem cell transplant con- solidation for selected patients. The introduction of molecularly targeted thera- pies has provided important incremental improvements for specific AML sub- types.2-4 Relapsed disease, mediated by the persistence of chemotherapy-resistant leukemic stem cells (LSC) is particularly difficult to treat, and accounts for much of the mortality burden associated with AML. For many older patients, treatment options that are both tolerable and efficacious do not yet exist. Anti-CD19 chimeric antigen receptor (CAR) T-cell therapies have provided a ground-breaking approach to cancer immunotherapy in B-cell acute lymphoblastic leukemia and B- cell non-Hodgkin lymphomas.5,6 While there is considerable interest in applying the principle of CAR technology in other diseases, progress in AML has been lim- ited to date by the absence of an ideal antigenic target, concerns about ‘on-target off-tumor’ toxicity including that to normal hematopoietic stem cells, and blast cell heterogeneity which exists both within and between patients.7-9.
Ferrata Storti Foundation
Haematologica 2022 Volume 107(2):437-445
Correspondence:
MICHAEL O’DWYER
michael.odwyer@nuigalway.ie
Received: September 11, 2020. Accepted: December 22, 2020. Pre-published: December 30, 2020.
https://doi.org/10.3324/haematol.2020.271908 ©2022 Ferrata Storti Foundation
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