Background: Current guidelines recommend factor IIa- or Xa-specific inhibitors over warfarin analogs for preventing thromboembolic stroke in patients with atrial fibrillation (AF).However, their plasma concentrations in Korean patients are not well understood. Methods: We conducted a single-center laboratory study to determine the distribution ranges of peak and trough concentrations of three factor Xa inhibitors (apixaban, edoxaban, and rivaroxaban) prescribed for preventing strokes in patients with AF. Patients receiving one of these drugs and undergoing blood specimen collection for laboratory tests were screened. Blood specimens were obtained from patients who had adhered to the prescribed drug regimen consistently for at least 1 week. Drug plasma concentrations were measured using heparin liquid-reagent technology-based anti-Xa chromogenic assays. Results: We selected 459 patients who were taking standard or on-label-reduced doses of apixaban (N = 252), edoxaban (N = 182), or rivaroxaban (N = 25). The 5th–95th percentile ranges of the peak concentrations were 84–414 ng/mL (apixaban), 72–424 ng/mL (edoxaban), and 97–517 ng/mL (rivaroxaban). The respective 5th–95th percentile ranges of the trough concentrations were 44–237 ng/mL, 23–93 ng/mL, and 13–219 ng/mL. Approximately 19.6% (apixaban), 33.3% (edoxaban), and 64.0% (rivaroxaban) of patients in each group had peak concentrations out of the predicted distribution ranges based on pharmacokinetic data. Approximately 7.3%, 52.8%, and 8.3% of patients had trough concentrations out of the predicted distribution ranges. Conclusions A considerable proportion of Korean patients with AF taking factor Xa inhibitors may require population-specific reference ranges to guide therapeutic monitoring.

Objective: Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors combined with endocrine therapy (ET) constitute the standard systemic treatment for estrogen receptor-positive, human epidermal growth factor 2-negative (ER+/HER2-) metastatic breast cancer (MBC). However, treatment responses remain heterogeneous, highlighting the need for reliable prognostic markers. This study aimed to evaluate the prognostic significance of 18F-fluorodeoxyglucose (FDG) PET/CT findings in this setting. Materials and Methods: This retrospective single-center cohort study included patients with ER+/HER2- MBC who underwent18F-FDG PET/CT before initiating CDK4/6 inhibitors plus ET between 2018 and 2023. Maximum standardized uptake value(SUVmax), whole-body metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured. Progression-free survival (PFS) and overall survival (OS) were evaluated as the primary and secondary outcomes, respectively, using multivariable Cox models. PET parameters (SUVmax, MTV, and TLG) were analyzed as both continuous and dichotomized variables based on median values, adjusting for relevant clinical covariates. Results: Among the 374 patients, 82 (21.9%) presented with de novo metastatic disease, and 357 (95.5%) received CDK4/6 inhibitors as first-line therapy. In multivariable Cox analysis, all continuous PET parameters were independently associated with PFS (adjusted hazard ratio for SUVmax 1.05 [95% confidence interval 1.02–1.08]; log-transformed MTV 1.16 [1.08–1.25]; and log-transformed TLG 1.14 [1.07–1.23]) and OS (SUVmax 1.08 [1.04–1.11]; log-transformed MTV 1.24 [1.12–1.38]; and log-transformed TLG 1.22 [1.11–1.34]) with all P < 0.001. Results based on dichotomized PET parameters were similar to those obtained with continuous values: PFS (adjusted hazard ratio for SUVmax ≥ 7.6, 1.41 [1.08–1.85]; MTV ≥ 21.2 cm 3 , 1.41 [1.08–1.86]; and TLG ≥ 78.9, 1.51 [1.14–1.99]) with P ≤ 0.013 and OS (1.43 [1.01–2.04]; 1.84 [1.28– 2.66]; and 1.73 [1.20–2.50], respectively) with P ≤ 0.046. Conclusion Pretreatment 18F-FDG PET/CT parameters are independent prognostic markers in patients with ER+/HER2- MBC receiving CDK4/6 inhibitors with ET, supporting their potential utility in risk stratification.

Purpose: Human epidermal growth factor receptor 2 (HER2) is amplified or overexpressed in various malignancies, including breast and gastric cancers, and is associated with poor prognosis. Although HER2-targeted therapies, such as trastuzumab, improve outcomes in HER2-positive tumors, resistance often develops, and HER2-low tumors remain largely untargeted. Trastuzumab deruxtecan (T-DXd; DS-8201a) is a HER2-targeted antibody-drug conjugate with potent activity in HER2-positive and HER2-low tumors. This study evaluates its antitumor mechanisms and efficacy in HER2-positive, HER2-low, and homologous recombination deficiency (HRD)–associated models. Materials and Methods: Effects of T-DXd were assessed in cancer cell lines with diverse HER2 expression and HRD status. In vivo efficacy was evaluated using a xenograft model derived from HER2-low SNU-601 gastric cancer cells. Results: T-DXd reduced HER2 phosphorylation and downstream signaling (AKT, ERK) in HER2-positive cells. It induced DNA damage accumulation, as evidenced by increased γH2AX and p-Chk1 expression, and triggered apoptosis through cleaved poly(ADP-ribose) polymerase and caspase-3 activation, confirmed by annexin V staining. Similar effects were observed in HER2-low cells, with greater sensitivity in HRD cells. In xenografts, T-DXd reduced tumor volume by up to 80% at 4 mg/kg and 10 mg/kg. Histological analyses showed decreased Ki-67 and increased apoptosis. Furthermore, T-DXd induced G2/M cell cycle arrest and nuclear anaplasia, suggesting disruption of chromosomal stability as a potential antitumor mechanism. No significant toxicity, including body weight loss, was observed. Conclusion These findings highlight T-DXd’s effectiveness in HER2-low and HRD tumors, supporting its broader clinical application, including strategies targeting DNA damage repair pathways.

Purpose: Sustained cell proliferation and cell cycle acceleration in cancer cells inherently increase DNA damage, which interferes with homeostatic replication and transcription. Ataxia telangiectasia and Rad3-related (ATR) is crucial for initiation of the DNA damage response, and ATR inhibitors, such as elimusertib, induce increased replication stress and DNA damage. We investigated the anti-tumor effects of elimusertib and its mechanism of action in relation to replication stress. Materials and Methods: Anti-tumor effects were evaluated by MTT assay and colony formation assay in breast cancer cell lines in vitro, in breast cancer cell xenografts in vivo, and in patient-derived xenograft models. Cell cycle was assessed by flow cytometry and BrdU assay was used to measure replicating cells and S-phase progression. Alkaline and neutral comet assay was used to measure single and double-stranded DNA damages, respectively. Results: Elimusertib delayed S-phase progression in MDA-MB-453 and MDA-MB-231 cells and induced caspase-7–dependent apoptosis. Furthermore, the increase in sub-G1 population in the fluorescence-activated cell sorting analysis and Annexin V assay also confirmed apoptotic cell death. In the BrdU assay, single-stranded DNA (ssDNA) increased in sensitive cells and aberrant ssDNA induced DNA damage in S-phase and eventually caused replication catastrophe. Finally, these anti-tumor effects were proven in in vivo xenograft and patient-derived xenograft models. Conclusion Elimusertib had anti-tumor effects and induced replication catastrophe in breast cancer cells with a high replication rate. Moreover, cells under high DNA replication stress were sensitive to elimusertib. Further studies and treatment strategies with elimusertib are warranted for cancers with a high replication rate.

Limited data exist regarding the real-world practices and clinical outcomes in patients with ischemic heart failure with reduced left ventricular ejection fractions (LVEFs).Using nationwide registry data from South Korea, we aimed to investigate long-term outcomes and clinical practices, especially implantable cardioverter defibrillators (ICDs) implantation, in patients with reduced LVEFs at least 40 days after acute myocardial infarction (AMI). Of 13,056 patients with AMI between 2011 and 2015, we analyzed 350 (median age, 66 years [interquartile range, 56-75]) who had LVEFs <40% on follow-up transthoracic echocardiogram 40 days after the index event. The primary outcome was cardiac-cause mortality at 3 years. Secondary outcomes comprised major cardiovascular events as well as outcomes defined by the use of ICDs, cardiac resynchronization therapy defibrillators (CRT-Ds), and electrophysiology studies. Among 350 patients, 39 (11.1%) died from cardiac causes during 3 years of follow-up. Eleven (3.1%) were hospitalized for ventricular tachycardia. The rate of ICD or CRT-D implantation up to 3 years was 5.7% (20/350). Cox time-to-event analysis revealed older age, LVEF <30%, diabetes mellitus, and previous MI or revascularization as positively associated with cardiac death, whereas the use of statins and body weight <67 kg were negatively associated. This nationwide Korean registry demonstrated that only 5.7% of patients who had reduced LVEFs after 40 days of AMI underwent ICD implantations over 3 years. Considering the high mortality, concerted efforts are needed to improve clinical outcomes for patients who may have been candidates for ICD implantation.

Purpose: To develop the 2025 update to the Korean colorectal cancer (CRC) screening guidelines by systematically evaluating recent evidence, integrating domestic data, and addressing changes since the 2015 guideline revision, thereby providing an evidence-based standard for clinicians and policymakers. Methods: A multidisciplinary committee developed the guidelines using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology. The process included formulation of three key questions addressing screening efficacy, diagnostic accuracy, and optimal screening age and interval. A systematic review of international guidelines and primary literature was conducted, yielding 327 eligible studies. In addition, a utility-based analysis using a Markov model was performed to determine optimal screening ages and intervals. Results: The evidence synthesis identified high-certainty evidence supporting the use of the fecal immunochemical test (FIT) for reducing CRC mortality and moderate-certainty evidence for colonoscopy. Evidence for computed tomographic colonography (CTC) and stool DNA testing was rated as very low certainty. Based on the evidence review and cost-utility analysis, the committee conditionally recommends CRC screening for asymptomatic, average-risk adults aged 45–74 years using either colonoscopy every 10 years or FIT every 1–2 years. CTC and stool DNA testing were not recommended owing to insufficient evidence. Conclusion The 2025 Korean Guidelines for Colorectal Cancer Screening present updated, evidence-based recommendations tailored to the domestic healthcare context. By conditionally endorsing both colonoscopy and FIT for individuals aged 45–74 years, these guidelines aim to improve population-level screening effectiveness and reduce the burden of CRC in South Korea.

Objective: General weakness is a common symptom in elderly patients (≥65 years), but it is difficult to evaluate. This study focused on the characteristics of elderly patients presenting to the emergency department (ED) with general weakness after the coronavirus disease 2019 (COVID-19) pandemic. Methods: A retrospective study was conducted to analyze the medical records of 308 elderly patients (≥65 years) who visited the ED from June 2023 to November 2023. This study examined whether factors, including nursing facilities, economic status, and neurodegenerative diseases (NDDs), have different influences on the characteristics of general weakness and performed tests. Results: Poor oral intake and nonspecific weakness accounted for the majority of accompanying symptoms. The symptoms, diagnosis, admission, and the number of imaging tests were similar regardless of the nursing facilities or home, NDDs, or economic status. Infections other than COVID-19 accounted for 31.2%, with pneumonia and urinary tract infections being the most common. COVID-19 accounted for 10.7%. Brain imaging tests, including computed tomography (CT) and magnetic resonance imaging, were performed within 39.9% of patients. Chest or abdominal CT was performed in 45.8% of patients. The infection rate, except for COVID-19, was higher in patients from nursing facilities, while the COVID-19 rate in the two groups was similar (P=0.005). A more aggressive brain imaging test was conducted in patients with NDDs (P=0.04). Conclusion After the COVID-19 pandemic, infections other than COVID-19, especially pneumonia and urinary tract infection, were the most common medical causes of general weakness in the elderly, followed by COVID-19. The proportion of COVID-19 as a cause of general weakness was similar between groups.

Autoimmune hemolytic anemia (AIHA) is a rare immune-mediated disorder in children that can present as primary or secondary to other diseases. Here, we report an unusual case of steroid-refractory warm AIHA in an 11-year-old girl whose condition was ultimately cured after removal of a benign ovarian tumor. Despite receiving multiple lines of therapy—including corticosteroids, rituximab, cyclosporine, sirolimus, and mycophenolate mofetil—the patient experienced recurrent hemolysis and steroid dependence for nearly four years. Abdominopelvic imaging performed to evaluate fever revealed bilateral ovarian cystic lesions, including a left-sided dermoid cyst. Surgical resection of the tumor led to complete and sustained hematologic remission, with normalization of hemoglobin, bilirubin, and reticulocyte counts, allowing discontinuation of all immunosuppressive agents. No recurrence of hemolysis was observed during 18 months of follow-up. This case highlights the potential for benign ovarian tumors to act as a rare secondary cause of AIHA through paraneoplastic or immune cross-reactive mechanisms. Awareness of such associations is crucial when evaluating pediatric patients with refractory or relapsing AIHA, as identification and removal of an occult tumor may achieve definitive resolution of hemolysis and avoid long-term immunosuppression.

Abrupt vessel closure (AVC) is a complication of percutaneous coronary intervention (PCI) and is defined as the sudden cessation of forward coronary blood flow due to a variety of mechanisms. The incidence of AVC has markedly decreased from approximately 3.0% in the early era to about 0.3% today. Nevertheless, cardiovascular interventionists must remain prepared to manage AVC effectively, given its significant impact on clinical outcomes.AVC can arise from several mechanisms, including dissection, intramural hematoma, intracoronary thrombosis, air embolism, vasospasm, and no-reflow. The clinical impact of AVC varies depending on the extent of myocardium affected, ranging from asymptomatic events or transient ischemic chest pain to cardiogenic shock or cardiac arrest. Both a general approach for stabilizing hemodynamic consequences and an etiology-specific management strategy are essential. Hasty decision-making may worsen the situation, whereas a structured approach—focused on hemodynamic stabilization, logical diagnostic processes, and targeted interventions—can improve outcomes. In this narrative review, we describe the mechanisms underlying each etiology, outline mechanism-specific management strategies, and discuss general approaches to managing patients with AVC through logical diagnostic and treatment processes. We hope this review offers valuable insights into this uncommon but significant complication and enhances readers’ skills in managing AVC more effectively during PCI.

Purpose: We report a case of epithelial downgrowth following multiple intraocular surgeries, successfully managed with en-bloc excision and cryotherapy during a third penetrating keratoplasty.Case summary: A 60-year-old male with a history of corneal edema, ectasia, and a mature cataract underwent extracapsular cataract extraction 10 years ago, followed by penetrating keratoplasty, scleral fixation of intraocular lens (IOL), and conjunctival advancement. Eight years after the initial surgery, a second penetrating keratoplasty was performed. Two years later, a whitish membrane was observed over the iris, accompanied by elevated intraocular pressure (IOP). Biopsy was performed, and 3 months later, due to persistent corneal edema and uncontrolled IOP, glaucoma drainage device implantation was carried out. However, the patient developed progressive shallowing of the anterior chamber and refractory IOP elevation. Consequently, a third penetrating keratoplasty was performed, including en-bloc excision of the affected iris tissue and adjunctive cryotherapy. Intraoperatively, a dense, sheet-like whitish epithelial membrane was observed covering the iris. Epithelial debris was seen displacing the iris and glaucoma valve tip anteriorly and extending over the IOL surface. Histopathological analysis confirmed epithelial downgrowth. The patient remained free of recurrence for 7 months postoperatively. Conclusions In patients with a history of multiple intraocular surgeries, meticulous wound closure and precise suturing—ensuring avoidance of full-thickness corneal perforation—are essential to prevent epithelial downgrowth. This rare but potentially sight-threatening complication results from the migration of corneal or conjunctival epithelial cells into the anterior chamber.