FDA Grants Fast Track to SIM0505 for Platinum-Resistant Ovarian Cancer

The FDA has granted fast track designation to SIM0505, a CDH6-directed antibody-drug conjugate, for the treatment of patients with platinum-resistant ovarian cancer. The regulatory decision is based on preclinical and early clinical findings suggesting the potential for SIM0505 to provide a therapeutic benefit in a patient population with limited treatment options.

SIM0505 is an investigational, next-generation antibody-drug conjugate that targets CDH6 and possesses a proprietary topoisomerase 1 payload. The developer has confirmed that a phase 1 study (NCT06792552) is evaluating SIM0505 as a treatment for patients with advanced solid tumors, with ovarian cancer and platinum-resistant disease as a focus. The company intends to present an initial data readout from the trial at the upcoming 2026 American Society of Clinical Oncology conference.

The first-in-human, open-label, multicenter phase 1 study is evaluating the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of SIM0505 in adult patients with advanced solid tumors. The study is divided into a dose-escalation phase and a dose-optimization phase. During the escalation portion, investigators are exploring multiple dose levels to determine the maximum tolerated dose and the recommended dose for further study. In the optimization phase, approximately 2 to 3 dose levels will be evaluated to refine the therapeutic index, specifically in cohorts for ovarian cancer, renal cell carcinoma, non-small cell lung cancer, and uterine cancer.

The treatment regimen consists of SIM0505 administered intravenously once every 21 days. To be eligible for the trial, patients must be 18 years or older and have histologically or cytologically confirmed advanced solid tumors that have progressed on at least 1 prior systemic anti-tumor regimen or for which no standard therapy is available. For the platinum-resistant ovarian cancer-specific cohort, patients must have high-grade serous or endometrioid ovarian cancer, as well as primary peritoneal cancer or fallopian tube cancer.

The primary end points of the trial in the dose-escalation phase are dose-limiting toxicities and adverse events. In the dose-optimization portion, it is objective response rate. The company plans to initiate dose optimization in patients with ovarian cancer in the second quarter of 2026.