Biology subjects

Vendetti, F. P.

Publications and source records attributed to Vendetti, F. P..

7 recordsLinked to original sources

bioRxiv2026

Transient ATR inhibition following ionizing radiation enhances immune-mediated antitumor response and survival

BackgroundATR activation following DNA damage from cancer treatments such as radiation can mitigate anticancer efficacy, making ATR inhibitors (ATRi) an attractive therapeutic. In vivo and in vitro studies have shown enhanced tumor cell radiosensitivity with the ATRi ceralasertib, elimusertib, and berzosertib, however, the potentiating effect of ATRi on ionizing radiation (IR) through immune-based mechanisms has only been studied with ceralasertib. MethodsWe aimed to determine if antitumor immune responses observed with ceralasertib in combination with IR extend to the other ATRi class members in the preclinical CT26 mouse model. We also examined the relationship between exposure and immune stimulation, efficacy and survival outcomes of each ATRi when combined with IR. ResultsCeralasertib and elimusertib, not berzosertib, synergized with IR in a dose and schedule-dependent manner to modify tumor antigen-specific CD8+ T cell populations in the draining lymph node. Transient ATRi therapy, combined with IR, enhances antitumor efficacy, promoted tumor shrinkage, and increased survival. ATRi elicited differential inflammatory gene induction and dose-dependent unique cytotoxicity profiles in vitro. ConclusionThe immune mediated antitumor effect of ATRi combined with radiation is dose and schedule dependent, and while likely a class effect, may differ between ATRi compounds.

cancer biology↗

bioRxiv2026

ATR kinase inhibitors induce mitochondrial fission in CD8+ T cells and impair immune memory in vivo

The DNA damage response kinase ATR restrains CDK1 activity during S and G2 phases of the cell cycle, confining CDK1-driven processes to mitosis. ATR kinase inhibitors were originally developed to potentiate chemotherapy-induced DNA damage at stalled replication forks and to disrupt DNA damage-induced cell cycle checkpoints. Recent evidence, however, reveals that these inhibitors also disrupt cell cycle organization in cells that have not sustained any DNA damage. We show that ATR kinase inhibitors potently trigger unscheduled mitochondrial fission, causing loss of mitochondrial mass in actively dividing CD8+ T cells that persists in memory CD8+ T cells. Moreover, ATR inhibition during the peak of CD8+ T cell expansion in a mouse model of LCMV Armstrong infection impairs the formation of immune memory. These findings carry significant clinical implications. ATR kinase inhibitors are currently being evaluated in clinical trials in combination with chemotherapy, radiation, and immune checkpoint inhibitors in patients where anti-tumor immune responses are recognized as a determinant of durable response. Our results identify an unexpected consequence of ATR inhibition that disrupts cellular metabolism with broad implications for both preclinical research and clinical application.

cancer biology↗

bioRxiv2025

Uracil-DNA glycosylase deficiency is associated with repressed tumor cell-intrinsic inflammatory signaling and altered sensitivity to exogenous interferons

2-deoxyuridine (dU) is a common DNA lesion resulting from cytosine deamination and from dUMP incorporation by DNA polymerases, both of which are prevalent in cancer. The primary mechanism that repairs dU lesions in genomic DNA is base excision repair initiated by Uracil-DNA Glycosylase 1 (UNG1). We generated Ung knockout mouse B16 melanoma cells to investigate the consequences of UNG deficiency in a well-characterized, immunoproficient, syngeneic mouse cancer model. We show that UNG-deficient ({Delta}UNG) B16 tumors have altered growth kinetics in vivo and that their delayed growth is T-cell dependent. Immune profiling revealed reduced CD8+ T cell infiltration but augmented CD4+ Th1 responses in {Delta}UNG tumors. In vitro, {Delta}UNG tumor cells exhibit strongly suppressed cell-intrinsic type-I interferon, type-II interferon, and inflammatory signaling gene expression signatures as well as altered cytokine and chemokine secretion. In vivo, {Delta}UNG tumors exhibit a modified inflammatory cytokine and chemokine milieu. Furthermore, {Delta}UNG tumor cells have altered sensitivity to exogenous interferons in vitro, with increased sensitivity to IFN-{gamma} but decreased sensitivity to IFN-/{beta}. Collectively, our data show that tumor cell-specific UNG deficiency results in an altered tumor microenvironment in vivo and provide proof-of-concept data for the use of UNG inhibitors to modulate inflammatory pathways in tumors.

cancer biology↗

bioRxiv2025

CDKN2ALow cancer cells outcompete macrophages for microenvironmental zinc to drive immunotherapy resistance

Anti-PD1 therapies are primarily thought to rely on functional T cell responses; yet tumors with limited T cell infiltration can still benefit, suggesting alternative mechanisms contribute to therapeutic efficacy. Indeed, we found that myeloid-rich, T cell-poor tumor models respond to anti-Pd1, and this is dependent on a cancer cell-macrophage crosstalk mediated by cancer cell Cdkn2a expression. Mechanistically, we found that cancer cells with decreased Cdkn2a expression (Cdkn2aLow), which occurs in [~]50% of all human cancers, reorganize zinc compartmentalization by upregulating the zinc importer Slc39a9 at the plasma membrane. Increased cancer cell plasma membrane Slc39a9 leads to intracellular zinc accumulation in cancer cells and depletion of zinc in the tumor microenvironment (TME), resulting in zinc-starved tumor-associated macrophages (TAMs) with reduced phagocytic activity. Restoring zinc availability in TAMs--via dietary supplementation or Slc39a9 knockdown in cancer cells--reprograms TAMs to a pro-phagocytic state and sensitizes Cdkn2aLow tumors to anti-Pd1 therapy. Remarkably, Slc39a9 knockdown tumors respond to anti-Pd1 in Rag1-/- mice, and co-injection of zinc-replete macrophages is sufficient to drive an anti-Pd1 response in immunodeficient mice, demonstrating the T cell-independent nature of this response. Clinically, TAMs from CDKN2ALow cancer patients show reduced zinc and phagocytosis gene signatures. Moreover, patients with lower circulating zinc levels have significantly worse time-to-event outcomes than those with higher levels. Together, these findings uncover a previously unrecognized mechanism by which Cdkn2aLow cancer cells outcompete TAMs for zinc, impairing their function and limiting anti-Pd1 efficacy. They also provide evidence that macrophages alone, without T cells, can enhance anti-PD1 response through zinc-mediated reprogramming of phagocytosis.

cancer biology↗

bioRxiv2024

Deoxyuridine-rich cytoplasmic DNA antagonizes STING-dependent innate immune responses and sensitizes resistant tumors to anti-PD-L1 therapy

DNA damage and cytoplasmic DNA induce type-1 interferon (IFN-1) and potentiate responses to immune checkpoint inhibitors. Our prior work found that inhibitors of the DNA damage response kinase ATR (ATRi) induce IFN-1 and deoxyuridine (dU) incorporation by DNA polymerases, akin to antimetabolites. Whether and how dU incorporation is required for ATRi-induced IFN-1 signaling is not known. Here, we show that ATRi-dependent IFN-1 responses require uracil DNA glycosylase (UNG)-initiated base excision repair and STING. Quantitative analyses of nine distinct nucleosides reveals that ATRi induce dU incorporation more rapidly in UNG wild-type than knockout cells, and that induction of IFN-1 is associated with futile cycles of repair. While ATRi induce similar numbers of micronuclei in UNG wild-type and knockout cells, dU containing micronuclei and cytoplasmic DNA are increased in knockout cells. Surprisingly, DNA fragments containing dU block STING-dependent induction of IFN-1, MHC-1, and PD-L1. Furthermore, UNG knockout sensitizes cells to IFN-{gamma} in vitro, and potentiates responses to anti-PD-L1 in resistant tumors in vivo. These data demonstrate an unexpected and specific role for dU-rich DNA in suppressing STING-dependent IFN-1 responses, and show that UNG-deficient tumors have a heightened response to immune checkpoint inhibitors. STATEMENT OF SIGNIFICANCEAntimetabolites disrupt nucleotide pools and increase dU incorporation by DNA polymerases. We show that unrepaired dU potentiates responses to checkpoint inhibitors in mouse models of cancer. Patients with low tumor UNG may respond to antimetabolites combined with checkpoint inhibitors, and patients with high tumor UNG may respond to UNG inhibitors combined with checkpoint inhibitors.

cancer biology↗

bioRxiv2022

Short-course but not prolonged treatment with ATR inhibitor AZD6738 integrates with radiotherapy to generate a tumor antigen-specific CD8+ T cell expansion in the periphery

ATR kinase is a central regulator of the DNA damage response. While ATR kinase inhibitors (ATRis) are known to sensitize cancer cells to DNA damage, their effect on immune cells is not known. Here we show in mice that short-course AZD6738 (ATRi) on days 1-3 decreases proliferating T cells in the tumor and periphery and that cessation of ATRi causes a proliferative rebound. Integrating radiation on days 1-2 (RT) with ATRi on days 1-3 increases IFN-{beta} in the tumor and activates tumor antigen-specific CD8+ T cells in the tumor-draining lymph node (DLN). RT with short-course ATRi induces an expansion of tumor antigen-specific CD8+ T cells in the DLN. In contrast, RT with prolonged daily ATRi blocks expansion of antigen-specific CD8+ T cells, despite increased IFN-{beta} and activation of CD8+ T cells. Our data identifies critical schedule considerations for ATRi with RT, immunotherapy and genotoxic therapies.

cancer biology↗

bioRxiv2022

ATR kinase inhibition induces thymineless death in proliferating CD8+ T cells

ATR kinase is a central regulator of the DNA damage response (DDR) and cell cycle checkpoints. ATR kinase inhibitors (ATRis) combine with radiation to generate CD8+ T cell-dependent responses in mouse models of cancer. We show that ATRis induce CDK1-dependent origin firing across active replicons in CD8+ T cells activated ex vivo while simultaneously decreasing the activity of rate-limiting enzymes for nucleotide biosynthesis. These pleiotropic effects of ATRi induce deoxyuridine (dU) contamination in genomic DNA, R loops, RNA-DNA polymerase collisions, and type-1 interferons (IFN-1). Remarkably, thymidine rescues ATRi-induced dU contamination, cell death, and IFN-1 expression in proliferating CD8+ T cells. Thymidine also rescues ATRi-induced cancer cell death. We propose that ATRi-induced dU contamination contributes to dose-limiting leukocytopenia and inflammation in the clinic and CD8+ T cell dependent anti-tumor responses in mouse models. We conclude that ATR is essential to limit dU contamination in genomic DNA and IFN-1 expression.

cancer biology↗