Therapy Resistance

Developmental reprogramming underlies chemotherapy resistance in favorable-histology Wilms tumor.

Children with favorable-histology Wilms tumor (FHWT) who relapse or whose tumors show blastemal predominance post-chemotherapy often face poor outcomes. The purpose of this study is to identify mechanisms of chemotherapy resistance in FHWT. We induce a patient-derived xenograft model (KT-47) to develop blastemal predominance after chemotherapy and to become resistant to vincristine, actinomycin-D, and doxorubicin (VAD). Multi-omics analyses reveal chromatin and transcriptional changes, including increased H3K4me3 and decreased H3K27me3 at stem cell and nephrogenesis gene loci. LIN28B is the most upregulated resistance-associated gene, linked to MYCN copy gain/upregulation and chromatin remodeling. ABCB1 expression correlates with interchromosomal enhancer interactions and functions as the mediator of chemotherapy resistance in vitro. These findings are validated in additional Wilms tumor models. Overall, resistance is associated with de-differentiation to a stem-like state and is driven by ABCB1 upregulation, suggesting that therapeutic strategies targeting chromatin regulation and drug efflux may be relevant in therapy-resistant Wilms tumor.

CLIM-TIME identifies metastatic microenvironment modulators for T cell therapy response.

The tumor microenvironment (TME) poses a major barrier to effective immunotherapy, yet high-throughput perturbation-mapping approaches to dissect TME spatial complexity and its contextual immune modulators remain lacking. Here, we introduce CRISPR-laser-captured microdissection (LCM) integration mapping of the tumor-immune microenvironment (CLIM-TIME), a scalable platform that integrates CRISPR screening with LCM of metastatic tumors for transcriptomic, deconvolution, and immunofluorescence analyses. CLIM-TIME enables spatially resolved mapping of how tumor suppressor gene (TSG) loss reshapes the TME and modulates immune responses. We identified seven distinct TME subtypes, revealing that DNA repair and Polycomb repressive complex (PRC) TSG loss is linked to immune-infiltrated TMEs sensitive to T cell therapy. In contrast, knockouts of TSGs in the Hippo pathway promoted immune evasion and therapy resistance by fostering myeloid-enriched but T cell-excluded TMEs with elevated extracellular matrix (ECM). Targeting the ECM-crosslinking enzyme LOXL2 effectively remodeled the metastatic TME, enhancing T cell infiltration and improving therapeutic efficacy in lung metastases across multiple cancers.

Guanine nucleotides drive ribosome biogenesis and glycolytic reprogramming in acute myeloid leukemia stem cells

Abstract Therapy resistance in acute myeloid leukemia (AML) remains a major clinical obstacle, particularly because of the persistence of leukemia stem cells (LSC) capable of metabolic adaptation. Although venetoclax (Ven) inhibits oxidative phosphorylation (OXPHOS), we found that Ven-resistant LSC undergo glycolytic reprogramming to bypass OXPHOS inhibition. This metabolic shift is supported by enhanced ribosome biogenesis, which is sustained by upregulated de novo guanine nucleotide biosynthesis. Abundant guanine nucleotides suppress the impaired ribosome biogenesis checkpoint (IRBC), leading to TP53 destabilization and persistent MYC expression. The inhibition of inosine monophosphate dehydrogenases (IMPDH1/2) depletes guanine nucleotides, activates IRBC, stabilizes TP53, represses MYC, and impairs the metabolic shift to glycolysis. This metabolic rewiring disrupts LSC stemness and suppresses the reconstitution of human AML cells in xenotransplantation experiments. Notably, the suppression of LSC stemness was observed regardless of Ven resistance or the TP53 mutational status of AML cells. These findings reveal that mutation-independent TP53 inactivation is involved in resistant AML and suggest that targeting guanine nucleotide biosynthesis may offer a clinically actionable strategy to eradicate therapy-resistant LSC.

STING synergizes with TOX suppressing HO-1 expression to trigger ferroptosis in tumor-infiltrating CD8+ T cell and immunotherapy resistance

Multi-omic Study of Cutaneous T-Cell Lymphoma Reveals Single Cell Clonal Evolution in Progression and Therapy Resistance

Cutaneous T-cell lymphoma (CTCL) remains a challenging disease due to its significant heterogeneity, therapy resistance, and relentless progression. Multi-omics technologies offer the potential to provide uniquely precise views of disease progression and response to therapy. We present here a comprehensive multi-omics view of CTCL clonal evolution, incorporating exome, whole genome, epigenome, bulk, single cell (sc) TCR, and scRNA sequencing of 99 clinically annotated serial skin, peripheral blood, and lymph node samples from 34 CTCL patients. We leveraged this extensive dataset to define the molecular underpinnings of CTCL progression in individual patients at single cell resolution with the goal of identifying clinically useful biomarkers and therapeutic targets. Our studies identified recurrent progression-associated clonal genomic alterations; we highlight mutation of CCR4, PI3K signaling, and PD-1 checkpoint pathways as evasion tactics deployed by malignant T-cells. We identified a gain of function mutation in STAT3 (D661Y) and demonstrated by CUT&RUN- and RNA-seq that it enhances binding to and transcription of genes in Rho GTPase pathways. With our previous work implicating this pathway in HDACi-resistant CTCL, these data provide further support for a previously unrecognized role for Rho GTPase pathway dysregulation in CTCL progression. Recurrent progression-associated mutations were common in the epigenetic modifier EZH2, suggesting that EZH2 inhibition may benefit patients with CTCL. Our findings support an approach in which genomic analysis is widely utilized for improved disease monitoring, biomarker-informed clinical trial design, and genome-guided therapeutic decision making. Moreover, these molecular changes present new opportunities for therapeutic targeting in this challenging and incurable cancer.