Biology subjects

Fidyt, K.

Publications and source records attributed to Fidyt, K..

3 recordsLinked to original sources

bioRxiv2025

The costimulatory domain influences CD19 CAR-T cell resistance development in B-cell malignancies.

CD19-CAR-T-cells emerge as a major therapeutic option for relapsed/refractory B-cell-derived malignancies, however approximately half of patients eventually relapse. To identify resistance-driving factors, we repeatedly exposed B-cell lymphoma/B-cell acute lymphoblastic leukemia to 4-1BB/CD28-based CD19-CAR-T-cells in vitro. Generated models revealed costimulatory domain-dependent differences in CD19 loss. While CD19-4-1BB-CAR-T-cells induced combination epitope/total CD19 protein loss, CD19-CD28-CAR-T-cells did not drive antigen-escape. Consistent with observations in patients relapsing after CD19-4-1BB-CAR-T-cells, we identified CD19 frameshift/missense mutations affecting residues critical for FMC63 epitope recognition. Mathematical simulations revealed that differences between CD19-4-1BB- and CD19-CD28-CAR-T-cells activity against low-antigen-expressing tumor contribute to heterogeneous therapeutic responses. By integrating in vitro and in silico data, we propose a biological scenario where CD19-4-1BB-CAR-T-cells fail to eliminate low-antigen tumor cells, fostering CAR-resistance. These findings offer mechanistic insight into the observed clinical differences between axi-cel (CD28-based) and tisa-cel (4-1BB-based)-treated B-cell lymphoma patients and advance our understanding on CAR-T resistance. Furthermore, we underscore the need for specific FMC63 epitope detection to deliver information on antigen levels accessible for CD19-CAR-T-cells. Visual abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=117 SRC="FIGDIR/small/640707v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@1728c4org.highwire.dtl.DTLVardef@759660org.highwire.dtl.DTLVardef@1e3a0deorg.highwire.dtl.DTLVardef@15653e4_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2023

CD20 expression regulates CD37 levels in B-cell lymphoma: implications for immunotherapies.

Rituximab (RTX) plus chemotherapy (R-CHOP) applied as a first-line therapy for lymphoma leads to a relapse in approximately 40% of patients. Therefore, novel approaches to treat aggressive lymphomas are being intensively investigated. Several RTX-resistant (RR) cell lines have been established as surrogate models to study resistance to R-CHOP. Our study reveals that RR cells are characterized with a major downregulation of CD37, a molecule currently explored as a target for immunotherapy. Using CD20 knockout (KO) cell lines, we demonstrate for the first time that CD20 and CD37 form a complex and the presence of CD20 stabilizes CD37 in the cell membrane. Consequently, we observe a diminished cytotoxicity of anti-CD37 monoclonal antibody (mAb) in complement-dependent cytotoxicity in both RR and CD20 KO cells that can be partially restored upon lysosome inhibition. On the other hand, the internalization rate of anti-CD37 mAb in CD20 KO cells is increased when compared to controls, suggesting unhampered efficacy of antibody drug conjugates. Importantly, even a major downregulation in CD37 levels does not hamper the efficacy of CD37-directed chimeric antigen receptor (CAR) T cells. In summary, we present here a novel mechanism of CD37 regulation with further implications for the use of anti-CD37 immunotherapies.

cancer biology↗

bioRxiv2023

Ammonia inhibits antitumor activity of NK cells by decreasing mature perforin

Immunotherapy revolutionized cancer treatment in the last decade. Natural killer (NK) cells are one of the key host immunity components against malignant cells. Thus, they are currently extensively investigated in the field of immunotherapy of cancer. Different approaches have been developed to improve the antitumor activity of NK cells. Nonetheless, tumor microenvironment remains an obstacle to effective NK cell-based therapies. Here, we demonstrated that a cancer-conditioned medium suppresses the anti-tumor activity of NK cells. Further, we found that ammonia, a by-product of cancer cell metabolism, accumulates in the cancer-conditioned medium and tumor microenvironment. We identified that ammonia impairs the cytotoxicity of NK cells as well as the effectiveness of antibody-based and chimeric antigen receptor (CAR)-NK-based therapies in vitro. Inhibited activity of NK cells was caused by decreased levels of perforin. This effect was dependent on the lysosomotropic features of ammonia and its ability to increase pH in acidic compartments. In consequence, upon contact with ammonia the mature form of perforin was decreased in NK cells leading to their dysfunction. Our findings demonstrate that in addition to its previously described role of promoting tumor growth as a nitrogen source for tumor biomass ammonia could promote tumor escape as an NK cells immune checkpoint. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=66 SRC="FIGDIR/small/567708v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@19db6a5org.highwire.dtl.DTLVardef@1424903org.highwire.dtl.DTLVardef@c795d7org.highwire.dtl.DTLVardef@13e7a8e_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LICancer-conditioned medium suppresses the antitumor activity of NK cells C_LIO_LIAmmonia accumulates in conditioned medium and in the tumor microenvironment C_LIO_LIImpaired cytotoxicity of NK cells is caused by ammonia that decreases perforin levels C_LIO_LIAmmonia causes NK cell dysfunction C_LI

cancer biology↗