NextCure Inc. (NASDAQ: NXTC) and Simcere Zaiming Pharmaceutical Co. announced the initiation of dose optimization for SIM0505, an investigational antibody drug conjugate targeting platinum-resistant ovarian cancer.

The dose optimization represents the next phase of a Phase 1 study evaluating SIM0505 in patients with advanced solid tumors. The drug combines an antibody targeting Cadherin-6 with a proprietary topoisomerase 1 inhibitor payload.

"Initiation of dose optimization highlights the promise of our novel CDH6-directed ADC and our focus on bringing SIM0505 to patients as quickly as possible," said Michael Richman, President and CEO of NextCure. The study aims to finalize dose selection and advance toward registrational studies.

The companies plan to expand trial sites in the United States and China while extending into Canada and Europe. Phase 1 data will be presented at the 2026 American Society of Clinical Oncology conference.

The Food and Drug Administration granted Fast Track designation to SIM0505 for platinum-resistant ovarian cancer. NextCure holds global rights to the drug excluding China, Hong Kong, Macau, and Taiwan, which remain with Simcere Zaiming.

The ongoing Phase 1 study is registered as NCT06792552 and focuses on advanced solid tumors with emphasis on platinum-resistant ovarian cancer. Simcere Zaiming, founded in 2023, operates as a subsidiary of Simcere Pharmaceutical Group Ltd (HKEX: 2096).