Case report of YL205 antibody-drug conjugate in platinum-resistant ovarian carcinoma

Photo by Dmytro Vynohradov / Unsplash

Frontiers in Medicine Published May 22, 2026 Medically reviewed May 22, 2026 Study authors: Yan-Xiang Tang, Hui Xiao, Zhen-Zi Tang, Lian Jian, Xingzi Guo DOI ↗ By Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease

Key Takeaway

Consider this case report as preliminary evidence for YL205 in a single patient with platinum-resistant ovarian cancer.

This publication is a single-patient case report describing the use of YL205, a novel NaPi2b-targeting antibody-drug conjugate, in a 40-year-old woman with FIGO stage IVB, BRCA-wildtype high-grade serous ovarian carcinoma. The patient received YL205 at 2.0 mg/kg every 3 weeks. The authors report that a complete radiological response was achieved after 24 weeks and CA-125 normalized to 3.5 U/ml. The response remained stable through the 48-week follow-up period.

The case highlights a positive clinical outcome in a single patient with platinum-resistant disease. The authors note that this represents the first clinical instance of a complete response observed with this agent. Safety findings indicated manageable grade 1–2 neutropenia symptoms, with no serious adverse events reported.

Key limitations acknowledged by the authors include the single-patient design, which precludes any conclusions about efficacy or safety for the broader population. The authors underscore the potential of next-generation ADCs with optimized linker-payload technologies, but this relevance is restrained by the case report format.

Practice relevance is limited to hypothesis generation. Clinicians should not generalize these findings to the broader platinum-resistant ovarian cancer population based on this single case report.

Study Details

Study typeSystematic review

EvidenceLevel 1

PublishedMay 2026

View Original Abstract ↓

High-grade serous ovarian carcinoma (HGSOC) remains a formidable challenge in the platinum-resistant setting (PROC). In the post-PARP inhibitor (PARPi) era, prior exposure reshapes resistance mechanisms, necessitating a shift from traditional platinum-free interval definitions to biomarker-driven strategies. We report an exceptional response to a next-generation ADC and review the evolving therapeutic landscape. A 40-year-old woman with FIGO stage IVB, BRCA-wildtype HGSOC developed rapid multi-drug resistance following neoadjuvant chemotherapy, optimal cytoreduction, and progression on maintenance olaparib/bevacizumab, gemcitabine, and a USP1 inhibitor. Following the identification of high NaPi2b expression (83% tumor proportion score), she initiated YL205, a novel NaPi2b-targeting antibody-drug conjugate (ADC) utilizing a topoisomerase I inhibitor payload, at 2.0 mg/kg every 3 weeks. The patient achieved a sustained complete radiological response (CR) and CA-125 normalization 3.5U/ml after 24 weeks, remaining stable through 48 weeks treatment. This represents the first clinical instance of CR observed with this agent. Adverse events were limited to manageable grade 1–2 neutropenia symptoms. This case underscores the potential of next-generation ADCs featuring optimized linker-payload technologies. By utilizing topoisomerase I inhibitors, agents like YL205 bypass microtubule-stabilization resistance induced by prior taxane exposure, while “bystander effects” address intratumoral heterogeneity. Longitudinal, biomarker-matched strategies and proactive toxicity management are essential to achieving deep tissue clearance in heavily pretreated HGSOC.