👤 Ryan B Corcoran

Oncogenic KRAS mutations are present in >90% of pancreatic ductal adenocarcinoma (PDAC) with KRASG12D being the most common. Mutant-selective KRASG12D inhibitors (KRASiG12D) have demonstrated promising initial clinical activity in KRASG12D-mutant PDAC. However, adaptive resistance to KRASi constrains efficacy in some tumor types, such as colorectal cancer, where EGFR-mediated RAS-MAPK pathway reactivation can be targeted toimprove response. Some studies have suggested a similar role for EGFR in PDAC, but the mechanisms of adaptive resistance to KRAS inhibition are unclear. Mechanisms of adaptive resistance to KRASiG12D were investigated in a panel of KRASG12D-mutant PDAC models. We observed RTK-driven adaptive reactivation of RAS pathway signaling following KRASiG12D in PDAC models. EGFR was a primary driver of adaptive RAS-MAPK reactivation in some models, but limited to those with epithelial differentiation. Conversely, adaptive RAS MAPK reactivation in models with mesenchymal differentiation was primarily driven by FGFR signaling. In clinical PDAC specimens from TCGA, EGFR and ERBB3 expression was highly correlated with expression of epithelial markers, while expression of FGFR1 and mesenchymal markers were correlated. Notably, a RAS(ON) multi-selective inhibitor, which inhibits both wild-type and mutant RAS, abrogated RAS-MAPK reactivation in combination with KRASi in both epithelial and mesenchymal models and led to more consistent antitumor activity compared to combinations of KRASi and EGFR blockade. In PDAC, adaptive RAS-MAPK reactivation following KRASG12D inhibition can be mediated by different RTKs and influenced by cell state. Combinations of mutant-selective KRASi and RAS(ON) multi-selective inhibitors may represent a promising universal strategy to surmount adaptive resistance in PDAC patients. Show less

Pan-fibroblast growth factor receptor (FGFR) inhibitors, targeting FGFR1-3 or FGFR1-4, are Food and Drug Administration-approved for FGFR2-driven cholangiocarcinoma. However, acquired resistance and dose-limiting toxicities from systemic FGFR inhibition constrain efficacy. Lirafugratinib (RLY-4008), a first-in-class FGFR2-selective inhibitor with activity against resistance-associated FGFR2 kinase domain mutations, shows promise in patients with FGFR2-altered solid tumors (ReFocus trial, NCT04526106). Defining acquired resistance mechanisms to selective FGFR2 targeting is essential for therapeutic development. Circulating tumor DNA (ctDNA) samples from 28 patients treated with lirafugratinib (16 FGFR inhibitor-naive, 12 FGFR inhibitor-refractory) were analyzed using targeted next-generation sequencing. Genomic alterations observed were compared with those reported in prior studies of pan-FGFR inhibitor resistance and validated in preclinical models. Polyclonal FGFR2 kinase domain mutations and receptor tyrosine kinase-mitogen activated protein kinase (RTK-MAPK) bypass alterations emerged as common lirafugratinib resistance mechanisms in the FGFR inhibitor-naive context (8/16 and 9/16 patients, respectively). Resistance profiles differed markedly from pan-FGFR inhibitors, with decreased FGFR2 V565F/L and N550H/K mutations, increased M538I and L618F mutations, and more frequent RTK-MAPK bypass alterations. The variant allele fraction was typically higher for FGFR2 kinase domain mutations, consistent with these alterations serving as primary resistance drivers. Preclinical studies confirmed differential sensitivity of these FGFR2 mutations to lirafugratinib. Importantly, lirafugratinib demonstrated clinical efficacy in the FGFR inhibitor-refractory setting, with ctDNA dynamics showing resolution of multiple FGFR2 mutations and persistence or emergence of others. Lirafugratinib retains activity against multiple mutations that confer clinical resistance to pan-FGFR inhibitors. However, diverse resistance mechanisms, including various kinase domain mutations and RTK-MAPK bypass alterations, remain challenges in the treatment of FGFR2-altered tumors, even with selective FGFR2 kinase inhibition. Show less

Transitions of cancer cells between distinct cell states, which are typically driven by transcription reprogramming, fuel tumor plasticity, metastasis, and therapeutic resistance. Whether the transitions between cell states can be therapeutically targeted remains unknown. Here, using the epithelial-to-mesenchymal transition (EMT) as a model, we show that the transcription reprogramming during a cell-state transition induces genomic instability through R-loops and transcription-replication conflicts, and the cell-state transition cannot occur without the ATR kinase, a key regulator of the replication stress response. ATR inhibition during EMT not only increases transcription- and replication-dependent genomic instability but also disrupts transcription reprogramming. Unexpectedly, ATR inhibition elevates R-loop-associated DNA damage at the SNAI1 gene, a key driver of the transcription reprogramming during EMT, triggering ATM- and Polycomb-mediated transcription repression of SNAI1. Beyond SNAI1, ATR also suppresses R-loops and antagonizes repressive chromatin at a subset of EMT genes. Importantly, inhibition of ATR in tumors undergoing EMT reduces tumor growth and metastasis, suggesting that ATR inhibition eliminates cancer cells in transition. Thus, during EMT, ATR not only protects genome integrity but also enables transcription reprogramming, revealing that ATR is a safeguard of cell-state transitions and a target to suppress tumor plasticity. Show less

FGFR2 and FGFR3 show oncogenic activation in many cancer types, often through chromosomal fusion or extracellular domain mutation. FGFR2 and FGFR3 alterations are most prevalent in intrahepatic cholangiocarcinoma (ICC) and bladder cancers, respectively, and multiple selective reversible and covalent pan-FGFR tyrosine kinase inhibitors (TKI) have been approved in these contexts. However, resistance, often due to acquired secondary mutations in the FGFR2/3 kinase domain, limits efficacy. Resistance is typically polyclonal, involving a spectrum of different mutations that most frequently affect the molecular brake and gatekeeper residues (N550 and V565 in FGFR2). Here, we characterize the activity of the next-generation covalent FGFR inhibitor, KIN-3248, in preclinical models of FGFR2 fusion+ ICC harboring a series of secondary kinase domain mutations, in vitro and in vivo. We also test select FGFR3 alleles in bladder cancer models. KIN-3248 exhibits potent selectivity for FGFR1-3 and retains activity against various FGFR2 kinase domain mutations, in addition to being effective against FGFR3 V555M and N540K mutations. Notably, KIN-3248 activity extends to the FGFR2 V565F gatekeeper mutation, which causes profound resistance to currently approved FGFR inhibitors. Combination treatment with EGFR or MEK inhibitors potentiates KIN-3248 efficacy in vivo, including in models harboring FGFR2 kinase domain mutations. Thus, KIN-3248 is a novel FGFR1-4 inhibitor whose distinct activity profile against FGFR kinase domain mutations highlights its potential for the treatment of ICC and other FGFR-driven cancers. Show less

The epigenome of stem cells occupies a critical interface between genes and environment, serving to regulate expression through modification by intrinsic and extrinsic factors. We hypothesized that aging and obesity, which represent major risk factors for a variety of diseases, synergistically modify the epigenome of adult adipose stem cells (ASCs). Using integrated RNA- and targeted bisulfite-sequencing in murine ASCs from lean and obese mice at 5- and 12-months of age, we identified global DNA hypomethylation with either aging or obesity, and a synergistic effect of aging combined with obesity. The transcriptome of ASCs in lean mice was relatively stable to the effects of age, but this was not true in obese mice. Functional pathway analyses identified a subset of genes with critical roles in progenitors and in diseases of obesity and aging. Specifically, Mapt, Nr3c2, App, and Ctnnb1 emerged as potential hypomethylated upstream regulators in both aging and obesity (AL vs. YL and AO vs. YO), and App, Ctnnb1, Hipk2, Id2, and Tp53 exhibited additional effects of aging in obese animals. Furthermore, Foxo3 and Ccnd1 were potential hypermethylated upstream regulators of healthy aging (AL vs. YL), and of the effects of obesity in young animals (YO vs. YL), suggesting that these factors could play a role in accelerated aging with obesity. Finally, we identified candidate driver genes that appeared recurrently in all analyses and comparisons undertaken. Further mechanistic studies are needed to validate the roles of these genes capable of priming ASCs for dysfunction in aging- and obesity-associated pathologies. Show less

Aged skin is prone to viral infections, but the mechanisms responsible for this immunosenescent immune risk are unclear. We observed that aged murine and human skin expressed reduced levels of antiviral proteins (AVPs) and circadian regulators, including Bmal1 and Clock. Bmal1 and Clock were found to control rhythmic AVP expression in skin, and such circadian control of AVPs was diminished by disruption of immune cell IL-27 signaling and deletion of Bmal1/Clock genes in mouse skin, as well as siRNA-mediated knockdown of CLOCK in human primary keratinocytes. We found that treatment with the circadian-enhancing agents nobiletin and SR8278 reduced infection of herpes simplex virus 1 in epidermal explants and human keratinocytes in a BMAL1/CLOCK-dependent manner. Circadian-enhancing treatment also reversed susceptibility of aging murine skin and human primary keratinocytes to viral infection. These findings reveal an evolutionarily conserved and age-sensitive circadian regulation of cutaneous antiviral immunity, underscoring circadian restoration as an antiviral strategy in aging populations. Show less

Aged skin is prone to viral infections, but the mechanisms responsible for this immunosenescent immune risk are unclear. We observed that aged murine and human skin expressed reduced antiviral proteins (AVPs) and circadian regulators including Bmal1 and Clock. Bmal1 and Clock were found to control rhythmic AVP expression in skin and such circadian-control of AVPs was diminished by disruption of immune cell interleukin 27 signaling and deletion of Bmal1/Clock genes in mouse skins, as well as siRNA-mediated knockdown of CLOCK in human primary keratinocytes. We found that treatment of circadian enhancing agents, nobiletin and SR8278, reduced infection of herpes simplex virus 1 (HSV1) in epidermal explants and human keratinocytes in a Bmal1/Clock-dependent manner. Circadian enhancing treatment also reversed susceptibility of aging murine skin and human primary keratinocytes to viral infection. These findings reveal an evolutionarily conserved and age-sensitive circadian regulation of cutaneous antiviral immunity, underscoring circadian restoration as an antiviral strategy in aging populations. Show less

The skin serves as the interface between the body and the environment and plays a fundamental role in innate antimicrobial host immunity. Antiviral proteins (AVPs) are part of the innate host defense system and provide protection against viral pathogens. How breach of the skin barrier influences innate AVP production remains largely unknown. In this study, we characterized the induction and regulation of AVPs after skin injury and identified a key role of TRPV1 in this process. Transcriptional and phenotypic profiling of cutaneous wounds revealed that skin injury induces high levels of AVPs in both mice and humans. Remarkably, pharmacologic and genetic ablation of TRPV1-mediated nociception abrogated the induction of AVPs, including Oas2, Oasl2, and Isg15 after skin injury in mice. Conversely, stimulation of TRPV1 nociceptors was sufficient to induce AVP production involving the CD301b Show less

Men diagnosed with low-risk prostate cancer (PC) are increasingly electing active surveillance (AS) as their initial management strategy. While this may reduce the side effects of treatment for prostate cancer, many men on AS eventually convert to active treatment. PC is one of the most heritable cancers, and genetic factors that predispose to aggressive tumors may help distinguish men who are more likely to discontinue AS. To investigate this, we undertook a multi-institutional genome-wide association study (GWAS) of 5,222 PC patients and 1,139 other patients from replication cohorts, all of whom initially elected AS and were followed over time for the potential outcome of conversion from AS to active treatment. In the GWAS we detected 18 variants associated with conversion, 15 of which were not previously associated with PC risk. With a transcriptome-wide association study (TWAS), we found two genes associated with conversion ( Show less

Crosstalk between T cells, dendritic cells, and macrophages in temporal leukocyte clusters within barrier tissues provides a new concept for T cell activation in the skin. Activated T cells from these leukocyte clusters play critical roles in the efferent phase of allergic contact hypersensitivity (CHS). However, the cytokines driving maintenance and survival of pathogenic T cells during and following CHS remain mostly unknown. Upon epicutaneous allergen challenge, we here report that macrophages produce IL-27 which then induces IL-15 production from epidermal keratinocytes and dermal myeloid cells within leukocyte clusters. In agreement with the known role of IL-15 as a T cell survival factor and growth cytokine, this signaling axis enhances BCL2 and survival of skin T cells. Genetic depletion or pharmacological blockade of IL-27 in CHS mice leads to abrogated epidermal IL-15 production resulting in a decrease in BCL2 expression in T cells and a decline in dermal CD8 Show less

UVR and immunosuppression are major risk factors for cutaneous squamous cell carcinoma (cSCC). Regulatory T cells promote cSCC carcinogenesis, and in other solid tumors, infiltrating regulatory T cells and CD8 Show less

In the skin, antiviral proteins and other immune molecules serve as the first line of innate antiviral defense. Here, we identify and characterize the induction of cutaneous innate antiviral proteins in response to IL-27 and its functional role during cutaneous defense against Zika virus infection. Transcriptional and phenotypic profiling of epidermal keratinocytes treated with IL-27 demonstrated activation of antiviral proteins OAS1, OAS2, OASL, and MX1 in the skin of both mice and humans. IL-27-mediated antiviral protein induction was found to occur in a STAT1- and IRF3-dependent but STAT2-independent manner. Moreover, using IL27ra mice, we demonstrate a significant role for IL-27 in inhibiting Zika virus morbidity and mortality following cutaneous, but not intravenous, inoculation. Together, our results demonstrate a critical and previously unrecognized role for IL-27 in cutaneous innate antiviral immunity against Zika virus. Show less