Biology subjects

Qasim, W.

Publications and source records attributed to Qasim, W..

4 recordsLinked to original sources

bioRxiv2025

Allo-defensive, multiplex base-edited, anti-CD38 CAR T cells for "off-the-shelf" Immunotherapy

Chimeric antigen receptor (CAR) T cell therapies are being widely investigated in both autologous and allogeneic settings, with gene editing providing new strategies to address barriers to mismatched cell therapies. Currently universal donor derived T cell therapies require intensive lymphodepletion and are prone to host-mediated rejection. CD38, a transmembrane glycoprotein involved in cell activation and bioenergetics, is a promising immunotherapy target for haematological malignancies. Disruption of CD38 expression using base editing prevented fratricide between T cells expressing anti-CD38 CAR (CAR38). Additional base editing enabled generation of a universal donor CAR38-T cells, devoid of endogenous TCR{beta} and Human Leukocyte Antigen (HLA) molecules after disruption of T Cell Receptor Beta Constant (TRBC), Beta-2 microglobulin (B2M), and Regulatory Factor X5 (RFX5). Removal of cell surface HLA expression enabled evasion of anti-HLA antibodies in sera from sensitised donors and reduced allo-stimulation in mixed lymphocyte cultures (MLCs), while TCR{beta} disruption prevented allo-reactivity. In MLCs, CAR38 expression enabled potent allo-defense activity against CD38+ allo-reactive cells. Multiplex-base-edited CAR38-T cells exhibited antigen-specific anti-leukemic activity against human B, T, and myeloid malignancies and inhibited disease progression in humanised murine xenograft models. CAR38-T cells offer a potent off-the-shelf strategy against CD38+ haematological malignancies and plasma cells associated with autoimmunity.

immunology↗

bioRxiv2024

Base edited "universal" donor CAR T cell strategies for acute myeloid leukaemia

Acute myeloid leukaemia (AML) is often aggressive and life-threatening with limited curative options. Immunotherapies including chimeric antigen receptor (CAR) T cell approaches are under investigation, but high levels of disease heterogeneity remain a major hurdle to achieving durable responses. Targeting of multiple surface antigens may ensure complete immunological coverage of leukemic blast populations, but such antigens are often also present on healthy haematopoietic populations. To address likely aplasia, strategies can be designed to bridge CAR T cell therapies to allogeneic stem cell transplantation (allo-SCT), as demonstrated in recent anti-CD7 CAR T cell studies. Here we report that monotherapy using base edited (BE) universal donor CAR T cells against CD33, CLL-1, or CD7 delivered inhibition of AML in immunodeficient mice when antigen expression was homogenous, but combined use of BE-CAR33 and BE-CARCLL-1 T cells was required to address heterogenous CLL-1-/+CD33-/+ disease. We also demonstrate that removal of shared CD7 antigens enabled compatibility of BE-CAR33 with BE-CAR7 T cells, including in a patient-derived xenograft (PDX) model of AML. Therapeutic strategies envisage pick and mix applications of base edited universal CAR T cells in combinations determined by patient-specific antigen profiles. Such approaches also offer the possibility of deep, cell-based, de-bulking and preparative conditioning ahead of allo-SCT followed by donor-derived reconstitution.

immunology↗

bioRxiv2021

A FOXN1 mutation competitively displaces wild-type FOXN1 from higher order nuclear condensates to cause immunodeficiency

The transcription factor FOXN1 is a master regulator of thymic epithelial cell development and function. Here we demonstrate that FOXN1 expression is differentially regulated during organogenesis and participates in multi-molecular nuclear condensates essential for the factors transcriptional activity. FOXN1s C-terminal sequence regulates the diffusion velocity within these aggregates and modulates the binding to proximal gene regulatory regions. These dynamics are significantly altered in a patient with a mutant FOXN1 which is modified in its C-terminal sequence. This mutant is transcriptionally inactive and acts as a dominant negative factor displacing wild-type FOXN1 from condensates and causing athymia and severe lymphopenia in heterozygotes. Expression of the mutated mouse ortholog, selectively impairs mouse thymic epithelial cell (TEC) differentiation revealing a gene dose dependency for individual TEC subtypes. We have therefore identified the cause for a primary immunodeficiency disease and determined the mechanism by which this FOXN1 gain-of-function mutant mediates its dominant negative effect.

immunology↗

bioRxiv2020

Base-edited CAR T Cells for combinational therapy against T cell malignancies

Targeting T cell malignancies using chimeric antigen receptor (CAR) T cells is hindered by T v T fratricide against shared antigens such as CD3 and CD7. Genome-editing can overcome such hurdles through targeted disruption of problematic shared antigens. Base editing offers the possibility of seamless disruption of gene expression through the creation of stop codons or elimination of splice donor or acceptor sites. We describe the generation of fratricide resistant, T cells by orderly removal of shared antigens such as TCR/CD3 and CD7 ahead of lentiviral mediated expression of CARs specific for CD3 or CD7. Molecular interrogation of base edited cells confirmed virtual elimination of chromosomal translocation events detected in conventional Cas9 treated cells. Interestingly, co-culture of 3CAR and 7CAR cells resulted in self-enrichment yielding populations that were 99.6% TCR-/CD3/-CD7-. 3CAR or 7CAR cells were able to exert specific cytotoxicity against their relevant target antigen in leukaemia lines with defined CD3 and/or CD7 expression as well as primary T-ALL cells. Co-cultured 3CAR/7CAR cells exhibited the highest level of cytotoxicity against T-ALL targets expressing both target in vitro and an in vivo human:murine chimeric model. While APOBEC editors can reportedly exhibit guide-independent deamination of both DNA and RNA, we found no evidence of promiscuous base conversion activity affecting CAR antigen specific binding regions which may otherwise redirect T cell specificity. Combinational infusion of fratricide resistant anti-T CAR T cells may enable enhanced molecular remission ahead of allogeneic haematopoietic stem cell transplantation for T cell malignancies.

molecular biology↗