Geographical heterogeneity in modeled CA-125 KELIM values: Insights from more than 50,000 real-world calculations on the Biomarker Kinetics platform.

5550 Background: The modeled CA-125 KELIM is a pragmatic indicator of primary tumor chemosensitivity during neoadjuvant (NACT) or adjuvant chemotherapy (post-primary cytoreductive surgery: ADJUVANT) in ovarian cancer. In a recent GCIG meta-analysis, Japanese patients with stage III–IV high-grade serous carcinoma had higher median KELIM values than Western populations (Corbaux.et.al., Proc ESGO 2025). To further assess potential geographical variations in chemosensitivity, we analyzed KELIM values calculated via the free online platform www.biomarker-kinetics.org , which performs approximately 30,000 calculations annually worldwide. Methods: All CA-125 KELIM calculations performed on the BK platform between April 2024 and January 2026 were extracted. Median KELIM values were compared separately for NACT and adjuvant settings across continents and countries. Results: During the 21-month study period, 50,055 KELIM calculations were recorded worldwide (NACT 59%; ADJUVANT 41%), originating from Asia (n=27,280; 55%), Europe (n=16,461; 33%), North America (n=3,690; 7%), South America (n=1,363; 3%), and rest of globe. Marked geographical variations in KELIM distribution were observed. In the NACT setting, median KELIM values (standardized by the classical cutoff) were significantly higher in patients from Asia (median 1.06, 95%CI [1.05–1.07]), Middle-East (median 0.96 [0.89–1.0.6]), and North America (median 0.91 [0.89–0.94]) compared to those from Europe (median 0.85 [0.84–0.86]) (P <0.0001). Within Asia, KELIM values were similarly elevated in China (n=10,617; median 1.07 [1.06–1.08]) and Japan (n=3,092; median 1.05 [1.03–1.07]) (P=NS). Similar results were noted in the ADJUVANT setting (Asia median 0.91, North America 0.80, vs Europe 0.75; all P<0.0001). Weighted median (τ = 0.5) quantile regression confirmed significantly higher standardized KELIM values in Asia (+0.21), Middle East (+0.12), and North America (+0.06) compared with Europe in the NACT setting. Similar outcomes were found in ADJUVANT setting : Asia (+0.16), Middle East (+0.28), and North America (+0.04) compared to Europe. Conclusions: Consistent with the GCIG meta-analysis, this global extraction of >50,000 KELIM calculations in the last 2 years confirms substantial geographic variability in tumor chemosensitivity, with higher median standardized KELIM values observed in patients from Asia and, to a lesser extent, the Middle East, while those from Europe exhibited the lowest values. These findings suggest potential important worldwide differences in primary tumor sensitivity to 1st-line carboplatin-paclitaxel chemotherapy and support the need for further biological and clinical investigations across diverse geographic and ethnic populations.