Capecitabine induces hand-foot syndrome through elevated thymidine phosphorylase-mediated locoregional toxicity and GSDME-driven pyroptosis that can be relieved by tipiracil.

BACKGROUND: Hand-foot syndrome (HFS) is a serious dose-limiting cutaneous toxicity of capecitabine-containing chemotherapy, leading to a deteriorated quality of life and negative impacts on chemotherapy treatment. The symptoms of HFS have been widely reported, but the precise molecular and cellular mechanisms remain unknown. The metabolic enzyme of capecitabine, thymidine phosphorylase (TP) may be related to HFS. Here, we investigated whether TP contributes to the HFS and the molecular basis of cellular toxicity of capecitabine. METHODS: TP-/- mice were generated to assess the relevance of TP and HFS. Cellular toxicity and signalling mechanisms were assessed by in vitro and in vivo experiments. RESULTS: TP-/- significantly reduced capecitabine-induced HFS, indicating that the activity of TP plays a critical role in the development of HFS. Further investigations into the cellular mechanisms revealed that the cytotoxicity of the active metabolite of capecitabine, 5-DFUR, was attributed to the cleavage of GSDME-mediated pyroptosis. Finally, we demonstrated that capecitabine-induced HFS could be reversed by local application of the TP inhibitor tipiracil. CONCLUSION: Our findings reveal that the presence of elevated TP expression in the palm and sole aggravates local cell cytotoxicity, further explaining the molecular basis underlying 5-DFUR-induced cellular toxicity and providing a promising approach to the therapeutic management of HFS.

GPCR-mediated EGFR transactivation ameliorates skin toxicities induced by afatinib.

Many G-protein-coupled receptor (GPCR) agonists have been studied for transactivating epidermal growth factor receptor (EGFR) signaling through extracellular or intracellular pathways. Accumulated evidence has confirmed that GPCR transactivation participates in various diseases. However, the clinical application of GPCR transactivation has not been explored, and more translational studies are needed to develop therapies to target GPCR-mediated EGFR transactivation. In cancer patients treated with EGFR inhibitors (EGFRi), especially afatinib, a unique acneiform rash is frequently developed. In this study, we first established the connection between GPCR transactivation and EGFRi-induced skin disease. We examined the ability of three different GPCR agonists to reverse signaling inhibition and ameliorate rash induced by EGFRi. The activation of different agonists follows unique time and kinase patterns. Rats treated with EGFRi show a similar skin phenotype, with rash occurring in the clinic; correspondingly, treatment with GPCR agonists reduced keratinocyte apoptosis, growth retardation and infiltration of inflammatory cytokines by transactivation. This phenomenon demonstrates that EGFR inhibition in keratinocytes regulates key factors associated with rash. Our findings indicate that maintaining EGFR signaling by GPCR agonists might provide a possible therapy for EGFR inhibitor-induced skin toxicities. Our study provides the first example of the translational application of GPCR transactivation in treating diseases.

Topical JAK inhibition ameliorates EGFR inhibitor-induced rash in rodents and humans.

Epidermal growth factor receptor inhibitors (EGFRis) are used to treat many cancers, but their use is complicated by the development of a skin rash that may be severe, limiting their use and adversely affecting patient quality of life. Most studies of EGFRi-induced rash have focused on the fully developed stage of this skin disorder, and early pathological changes remain unclear. We analyzed high-throughput transcriptome sequencing of skin samples from rats exposed to the EGFRi afatinib and identified that keratinocyte activation is an early pathological alteration in EGFRi-induced rash. Mechanistically, the induction of S100 calcium-binding protein A9 (S100A9) occurred before skin barrier disruption and led to keratinocyte activation, resulting in expression of specific cytokines, chemokines, and surface molecules such as interleukin 6 (Il6) and C-C motif chemokine ligand 2 (CCL2) to recruit and activate monocytes through activation of the Janus kinase (JAK)-signal transducers and activators of transcription (STAT) pathway, further recruiting more immune cells. Topical JAK inhibition suppressed the recruitment of immune cells and ameliorated the severity of skin rash in afatinib-treated rats and mice with epidermal deletion of EGFR, while having no effect on EGFRi efficacy in tumor-bearing mice. In a pilot clinical trial (NCT05120362), 11 patients with EGFRi-induced rash were treated with delgocitinib ointment, resulting in improvement in rash severity by at least one grade in 10 of them according to the MASCC EGFR inhibitor skin toxicity tool (MESTT) criteria. These findings provide a better understanding of the early pathophysiology of EGFRi-induced rash and suggest a strategy to manage this condition.

DNA damage-mediated cellular senescence promotes hand-foot syndrome that can be relieved by thymidine prodrug.

Hand-foot syndrome (HFS) is a widely recognized dose-limiting cutaneous toxicity effect of fluoropyrimidine chemotherapy agents that impairs clinical benefits and treatment outcomes. Even though the cause and pathophysiology of HFS are relatively widely reported, how the toxicity of fluoropyrimidine translates into persistent inflammation has not been studied. Additionally, prevention and treatment strategies for HFS based on its mechanistic occurrence and development are scarce. In our study, we demonstrated that cGAS-STING signaling pathway-mediated cellular senescence played a critical role in the inflammatory reaction and provided a therapeutic solution for HFS. Mechanistically, DNA damage, as the primary cytotoxic cause, in keratinocytes induces cell cycle arrest, activates the cGAS-STING signaling pathway, and subsequently mediates cellular senescence, ultimately fueling a robust secondary inflammatory response that results in HFS. More importantly, the thymidine prodrug thymidine diacetate was proven to be effective in preventing HFS by compensating for thymidylate deficiency to facilitate the replication and repair of DNA and thus causing the escape from cellular senescence. These data highlight the importance of DNA damage-mediated cellular senescence in the etiology of HFS and provide a potential therapeutic anchor point for fluoropyrimidine-induced HFS.

Prophylactic Effect of Nitric Oxide Donors on Rat Models of EGFR Inhibitor‒Induced Cutaneous Toxicities.

EGF receptor (EGFR) inhibitors have been established as first-line standard-of-care therapies for nonsmall cell lung cancer but are frequently accompanied by adverse dermatological effects, in particular, acneiform rash. There is no effective clinical intervention, partially because of its poorly understood etiology. In this study, we show that inhibition of EGFR initiated keratinocyte HaCaT cell cycle arrest and apoptosis, which fueled a robust secondary inflammatory response. Rats gavaged with EGFR inhibitor showed a phenotype similar to that of clinical patients, which was in line with the interrupted functions observed in HaCaT keratinocytes. We found that a nitric oxide donor, nitroglycerin, was a feasible treatment alternative for EGFR inhibitor‒induced rash. Restoration of epidermal extracellular signal‒regulated kinase and a reduction in signal transducer and activator of transcription 3 signaling through nitroglycerin treatment rescued the cellular functions that had been damaged in vitro and further ameliorated the rash in rat models. In addition, the efficacy of nitroglycerin was superior to that of existing clinical interventions. These data highlighted the importance of epidermal EGFR signaling and led to the identification of a small-molecule nitric oxide donor as a mediator that can maintain EGFR pathway functions during anti-EGFR therapies, providing a therapeutic anchor point for adverse EGFRI-induced skin effects.

Nitric oxide in multikinase inhibitor-induced hand-foot skin reaction.

Hand-foot skin reaction (HFSR) is the most debilitating and prevalent side effect caused by multikinase inhibitors (MKIs) that share vascular endothelial growth factor receptor (VEGFR) as the common inhibition target, such as sorafenib, regorafenib, axitinib, etc. Though not life-threatening, HFSR can significantly deteriorate patients' quality of life and jeopardize the continuity of cancer therapy. Despite years of efforts, there are no FDA-approved treatments for HFSR and the understanding of the precise pathogenic mechanism is still limited. In this study, we hypothesized that nitric oxide has the potential therapeutic effect to reverse the toxicity caused by MKI through upregulation of several VEGF/VEGFR downstream signaling pathways. We found that glyceryl trinitrate (GTN), a nitric oxide donor, could stimulate cell proliferation, migration, and protect cells from apoptosis induced by MKIs in vitro. Local application of GTN mitigated tissue damage in a rat model, while not impacting the anti-tumor effect of the MKI in HepG2 tumor-bearing mice. Finally, GTN ointment alleviated cutaneous damages and improved quality of life in 6 HFSR patients. Our study proposed and validated the mechanism to counteract VEGFR inhibition, providing GTN as the potential treatment to MKI-induced HFSR, which may further improve the therapeutic window of various MKI based cancer therapies.