Biology subjects

De Smet, E.

Publications and source records attributed to De Smet, E..

3 recordsLinked to original sources

bioRxiv2026

Broadly neutralizing antibody-secreting CAR-T cells elicit Fc-mediated effector functions in vitro and suppress HIV in humanized mice

Despite significant advances in antiretroviral therapy (ART) that have transformed human immunodeficiency virus (HIV) infection from a fatal diagnosis to a manageable chronic condition, the persistent viral reservoir necessitates lifelong treatment underscoring the critical need for curative interventions. Viral persistence within anatomically distinct reservoirs, coupled with HIV-associated immune dysregulation accentuates the need for innovative combination immunotherapies that can act through multiple mechanisms. We introduce the Hybrid chimeric antigen receptor (CAR) platform: a dual-function immunotherapy that combines the targeted cytotoxicity of CAR-T cells with the secretion of broadly neutralizing antibodies (bNAbs). This approach enables direct elimination of HIV-infected cells, neutralization of free virus and Fc-mediated effector recruitment. In vitro, Hybrid CAR-T cells eliminated HIV-infected CD4+ T cells while the secreted bNAbs neutralized HIV and mediated robust Fc-effector functions including antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP). In humanized mice, Hybrid CAR-T treatment achieved more than a 9-fold reduction in plasma viremia, accompanied by a significant decrease in viral levels across tissues, with circulating bNAbs detected in plasma. Collectively, these findings highlight the potential of Hybrid CAR-T cells as a synergistic next-generation therapeutic that bridges cellular and humoral immunity, supporting their translational promise as a strategy toward functional HIV cure.

immunology↗

bioRxiv2023

Integrative assessment of total and intact HIV-1 reservoir by a five-region multiplexed Rainbow digital PCR assay

Persistent latent reservoirs of intact HIV-1 proviruses, capable of rebounding despite suppressive ART, hinder efforts towards an HIV-1 cure. Hence, assays specifically quantifying intact proviruses are crucial to assess the impact of curative interventions. Clinical trials have utilized two recent assays: intact proviral DNA assay (IPDA) and Q4PCR. While IPDA is more sensitive due to amplifying short fragments, it may overestimate intact fractions by relying only on two small regions. Q4PCR is sequencing-based and its performance might be subjected to bias against full-length proviruses. Leveraging digital PCR (dPCR) advancements, we developed the Rainbow 5-plex proviral HIV-1 DNA assay, assessing it with standard materials and samples from 69 PLWH. The Rainbow assay proved equally sensitive but more specific than IPDA, is not subjected to bias against full-length proviruses, enabling high-throughput quantification of total and intact reservoir size. This innovation offers potential for targeted evaluation and monitoring of rebound-competent reservoirs, contributing to HIV-1 management and cure strategies. TeaserThe 5 color HIV-1 Rainbow digital PCR assay offers a multi-level view on the HIV reservoir in one snapshot reaction.

molecular biology↗

bioRxiv2020

RRM2 is a target for synthetic lethal interactions with replication stress checkpoint addiction in high-risk neuroblastoma

Neuroblastoma is a pediatric tumor originating from the sympathetic nervous system responsible for 10-15 percent of all childhood cancer deaths. Half of all neuroblastoma patients present with high-risk disease at diagnosis. Despite intensive multi-modal therapies nearly 50 percent of high-risk cases relapse and die of their disease. In contrast to the overall paucity of mutations, high-risk neuroblastoma nearly invariably present with recurrent somatic segmental chromosome copy number variants. For several focal aberrations (e.g. MYCN and LIN28B amplification), the direct role in tumor formation has been established. However, for recurrent aberrations, such as chromosome 2p and 17q gains, the identification of genes contributing to tumor initiation or progression has been challenging due to the scarcity of small segmental gains or amplifications. In this study, we identified and functionally evaluated the ribonucleotide reductase regulatory subunit 2 (RRM2) as a top-ranked 2p putative co-driver and therapeutic target in high-risk neuroblastoma enforcing replicative stress resistance. In vitro knock down and pharmacological RRM2 inhibition highlight RRM2 dependency in neuroblastoma cells, further supported by the finding that co-overexpression of RRM2 in a d{beta}h-MYCN transgenic zebrafish line increased tumor penetrance with 80% and accelerated tumor formation. Given the critical role of RRM2 in replication fork progression and regulation of RRM2 through ATR/CHK1 signaling, we tested combined RRM2 and ATR/CHK1 small molecule inhibition with triapine and BAY1895344/prexasertib respectively, and observed strong synergism, in particular for combined RRM2 and CHK1 inhibition. Transcriptome analysis following combinatorial drugging revealed HEXIM1 as one of the strongest upregulated genes. Using programmable DNA binding of dCas9 with a promiscuous biotin ligase, RRM2 promotor bound proteins were identified including HEXIM1 and NurRD complex members, supporting a cooperative role for HEXIM1 upregulation together with CHK1 inhibition in further attenuating RRM2 expression levels. We evaluated the impact of combined RRM2/CHK1 inhibition in vivo, with treatment of a murine xenograft model showing rapid and complete tumor regression, without tumor regrowth upon treatment arrest. In conclusion, we identified RRM2 as a novel dependency gene in neuroblastoma and promising target for synergistic drug combinations with small compounds targeting DNA checkpoint regulators.

cancer biology↗