Poorebrahim, M. | bioRxiv Science

bioRxiv2025

OVEREXPRESSION OF TUMORPROTECTIVE CLUSTERIN PREVENTS EXHAUSTION OF TRANSGENIC T CELLS

1T cell therapies, such as chimeric antigen receptor (CAR) T cells and T cell receptor (TCR) transgenic (tg) T cells, are a promising approach in the treatment of solid malignancies but are limited by T cell exhaustion caused by chronic antigen stimulation. Clusterin (CLU) is a chaperone protein known to protect both normal and malignant cells, from metabolic stress and reactive oxygen species (ROS). In this study, we investigated whether overexpression (OE) of CLU in TCRtg T cells and CAR-T cells respectively can reduce exhaustion induced by chronic antigen stimulation and enhance T cell functionality against Ewing sarcoma (EwS). Among other cytoprotective genes, we found that CLU was significantly downregulated in dysfunctional tumor infiltrating lymphocytes. Therefore, we engineered EwS-directed TCRtg T cells targeting a Chondromodulin-1 (Chm1)-derived peptide and GD2 CAR-T cells to overexpress CLU. We show here that CLU is downregulated in T cells following activation by tumor cells. CLU-overexpressing T cells exhibit decreased expression of exhaustion markers (PD1, LAG3) and reduced apoptosis after repetitive stimulation. These cells demonstrated improved infiltration into tumor spheroids and maintained functionality under hypoxic conditions. In vivo, CLU-overexpressing T cells showed enhanced persistence and a trend towards reduced tumor growth. Mechanistically, proteomic analysis suggested that reduced ribosomal activity might delay T cell exhaustion, implicating metabolic reprogramming. In conclusion, CLU OE in tg T cells enhances their persistence and functionality by mitigating exhaustion, possibly through modulation of ribosomal activity and metabolic pathways. This strategy holds potential for improving adoptive T cell therapies against solid tumors.

immunology↗

bioRxiv2024

CD38 biallelic loss is a recurrent mechanism of resistance to anti-CD38 antibodies in multiple myeloma.

Monoclonal antibodies targeting CD38 are a therapeutic mainstay in multiple myeloma (MM). While they have contributed to improved outcomes, most patients still experience disease relapse, and little is known about tumor-intrinsic mechanisms of resistance to these drugs. Antigen escape has been implicated as a mechanism of tumor cell evasion in immunotherapy. Yet, it is unknown whether MM cells can develop permanent resistance to anti-CD38 antibodies by acquiring genomic events leading to biallelic disruption of the CD38 gene locus. Here, by using whole genome and whole exome sequencing data from 701 newly diagnosed patients, 67 patients at relapse with naivety to anti-CD38 antibodies, and 50 patients collected at relapse following anti-CD38 antibodies. We report a loss of CD38 in 20% (10/50) of patients post-CD38 therapy, three of which exhibited a loss of both copies. Two of these cases showed convergent evolution where distinct subclones independently acquired similar advantageous variants. Functional studies on missense mutations involved in biallelic CD38 events revealed that two variants, L153H and C275Y, decreased binding affinity and antibody-dependent cellular cytotoxicity of the commercial antibodies Daratumumab and Isatuximab. However, a third mutation, R140G, conferred selective resistance to Daratumumab, while retaining sensitivity to Isatuximab. Clinically, patients with MM are often rechallenged with CD38 antibodies following disease progression and these data support a role for next generation sequencing to guide treatment selection.

cancer biology↗