Jong-Baeck Lim

Hyein Kang, M.D., Jaehyeok Jang, M.D., Heekang Choi, M.D., Hanmil Jang, M.D., John Hoon Rim, M.D., Jong-Baeck Lim, M.D.. Lab Med Online 2026;16:122-7. https://doi.org/10.47429/lmo.2026.16.2.122

Background: Fibroblast growth factor 23 (FGF23) is a bone-derived phosphaturic hormone that is essential for phosphate homeostasis. Elevated FGF23 levels underlie FGF23-related hypophosphatemic rickets and tumor-induced osteomalacia. Despite its clinical importance, population-based reference intervals (RIs) for intact FGF23 using the widely deployed LIAISON XL automated chemiluminescent immunoassay platform (DiaSorin) are lacking for East Asian populations. Methods: We established method-specific RIs for intact FGF23 (iFGF23) in 386 healthy Korean adults (193 males and 193 females; age, 20–79 years) following the Clinical and Laboratory Standards Institute EP28-A3c guidelines. After the Box–Cox transformation and Horn’s outlier detection, the RIs were derived using nonparametric methods (2.5th–97.5th percentiles). The necessity for partitioning was assessed using the Harris–Boyd method. Associations between iFGF23 levels and demographic, anthropometric, and biochemical parameters were examined using Pearson’s correlation coefficients. Results: The overall nonparametric RI was 28.04–100.33 pg/mL (90% CI: 25.77–31.91 to 96.29–109.20). Age emerged as the primary determinant requiring partitioning, with young adults (20–29 years) exhibiting significantly lower concentrations than older adults (≥30 years): 25.73–78.76 versus 32.01–107.00 pg/mL. A sex-stratified analysis confirmed that this age effect persisted independently in both males and females. Although males had higher median iFGF23 than females (65.03 vs. 51.98 pg/mL, p < 0.001), Harris–Boyd analysis did not support sex-based partitioning ( z = 5.17, z * = 5.38). Intact FGF23 was significantly correlated with age ( r = 0.278), estimated glomerular filtration rate ( r = –0.254), and alkaline phosphatase ( r = 0.143; all p ≤ 0.005), but not with traditional mineral metabolism parameters (phosphate, calcium, parathyroid hormone, and 25-hydroxyvitamin D). Conclusions: This study provides the first population- and method-specific RIs for intact FGF23 in an East Asian population and establishes critical age-stratified benchmarks for clinical interpretation. The distinct RI in young adults underscores the necessity of age-appropriate reference standards for diagnosing and monitoring phosphate homeostasis disorders. These findings highlight the importance of population-specific reference data in the absence of assay harmonization.

Hyeon Kyu Choi, M.D., Hyesoo Kim, M.D., Mi Hwa Shin, Chul Hoon Kim, M.D., Ph.D., Ah Young Leem, M.D., Ph.D., Su Hwan Lee, M.D., Ph.D., Kyung Soo Chung, M.D., Ph.D., Young Sam Kim, M.D., Ph.D., Hanmil Jang, M.D., John Hoon Rim, M.D., Ph.D., Byung Hoon Kho, Gi Hun Seoung, Wondong Kim, Jong-Baeck Lim, M.D., Ph.D., and Moo Suk Park, M.D., Ph.D.. Ann Lab Med -0001;0:. https://doi.org/10.3343/alm.2025.0302

Background: The combination of epirubicin, cisplatin, and 5-fluorouracil (ECF) is widely used for gastric cancer treatment. However, cancer cells can acquire chemoresistance over multiple treatment cycles, leading to recurrence. This study aimed to investigate a novel biomarker for predicting ECF resistance and its biological roles in gastric cancer. Methods: ECF-resistant (ECF-R) gastric cancer cell lines were established through stepwise ECF treatment. Transcriptome analysis was performed to identify resistance-related genes, which were validated in tumor organoids and in vivo models. Additionally, gastric cancer patient tumor tissues were analyzed for clinical relevance. Results: Transcriptome analysis revealed that NINJURIN2 and CD44 were highly expressed in ECF-R cells but rarely expressed in normal gastric tissues. NINJURIN2 inhibition significantly increased chemosensitivity to ECF in vitro and in vivo. Liquid chromatography–tandem mass spectrometry identified periostin as a binding partner of NINJURIN2, mediating chemoresistance. Furthermore, VAV2 phosphorylation was markedly upregulated in ECF-R cells but was inhibited by NINJURIN2 knockdown. Clinical analysis showed that high NINJURIN2 expression correlated with poor survival outcomes in gastric cancer patients. Conclusion: Our findings suggest that NINJURIN2 can be used as a novel biomarker for chemoresistant gastric cancer patients and that inhibiting NINJURIN2 along with standard chemotherapy could prevent chemoresistance-associated relapse in gastric cancer.

Hyein Kang, Hanmil Jang, John Hoon Rim, Sang-Guk Lee, and Jong-Baeck Lim. Lab Med Qual Assur 2025;47:23-7. https://doi.org/10.15263/jlmqa.2025.47.1.23

Park K, et al. J Korean Med Sci. 2024 Oct;40:e4. https://doi.org/10.3346/jkms.2025.40.e4

Background For best efficacy, vaccines must provide long-lasting immunity. To measure longevity, memory from B and T cells are surrogate endpoints for vaccine efficacy. When antibodies are insufficient for protection, the immune response must rely on T cells. The magnitude and differentiation of effective, durable immune responses depend on antigen-specific precursor frequencies. However, development of vaccines that induce durable T-cell responses for cancer treatment has remained elusive. Methods To address long-lasting immunity, patients with HER2+ (human epidermal growth factor receptor 2) advanced stage cancer received HER2/neu targeted vaccines. Interferon-gamma (IFN-γ) enzyme-linked immunosorbent spot measuring HER2/neu IFN-γ T cells were analyzed from 86 patients from three time points: baseline, 1 month after vaccine series, and long-term follow-up at 1 year, following one in vitro stimulation. The baseline and 1-month post-vaccine series responses were correlated with immunity at long-term follow-up by logistic regression. Immunity was modeled by non-linear functions using generalized additive models. Results Antigen-specific T-cell responses at baseline were associated with a 0.33-log increase in response at long-term follow-up, 95% CI (0.11, 0.54), p=0.003. 63% of patients that had HER2/neu specific T cells at baseline continued to have responses at long-term follow-up. Increased HER2/neu specific T-cell response 1 month after the vaccine series was associated with a 0.47-log increase in T-cell response at long-term follow-up, 95% CI (0.27, 0.67), p=2e-5. 74% of patients that had an increased IFN-γ HER2 response 1 month after vaccines retained immunity long-term. As the 1-month post-vaccination series precursor frequency of HER2+IFN-γ T-cell responses increased, the probability of retaining these responses long-term increased (OR=1.49 for every one natural log increase of precursor frequency, p=0.0002), reaching an OR of 20 for a precursor frequency of 1:3,000 Conclusions Patients not destined to achieve long-term immunity can be identified immediately after completing the vaccine series. Log-fold increases in antigen-specific precursor frequencies after vaccinations correlate with increased odds of retaining long-term HER2 immune responses. Further vaccine boosting or immune checkpoint inhibitors or other immune stimulator therapy should be explored in patients that do not develop antigen-specific T-cell responses to improve overall response rates.

Background: While the real-world impact of estimated glomerular filtration rate (eGFR) equation change on clinical outcome in a longitudinal cohort setting is limited, external valuation of equation performance should be performed in different population cohorts. This study aimed to compare differential impacts of eGFR values, calculated by 5 equations in a Korean patient population, on clinical outcomes. Methods: This retrospective longitudinal follow-up cohort study analyzed 23 246 participants with standardized creatinine/cystatin C assay-based laboratory results. The primary exposure was baseline eGFR calculated by 5 different equations including the recently developed 2021 race-free Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations. Clinical outcomes including all-cause mortality, renal replacement therapy, and albuminuria were analyzed to estimate the hazard ratio of the eGFR on clinical outcomes. Results: Among the 5 equations, CKD-EPI 2021 with creatinine and cystatin C (CKD-EPI 2021-CrCys) showed an earlier increase in hazard ratios for all clinical outcomes, while CKD-EPI 2012 with cystatin C showed a higher hazard ratio for all-cause mortality at low eGFR. Replacing CKD-EPI 2012 with CKD-EPI 2021-CrCys, 5.4% of patients with mortality and 3.3% of patients who received renal replacement therapy were reclassified to a lower risk stage. Conclusions: The 2021 CKD-EPI equations were acceptable in a Korean population, with better predictive power for clinical outcomes when compared to previous equations. The updated race-free factors for eGFR calculation improved identification of patients at risk for clinical outcomes.