FDA Gives Fast Track Status to SIM0505 in Platinum-Resistant Ovarian Cancer

The FDA has granted fast track designation to SIM0505 for the treatment of patients with platinum-resistant ovarian cancer (PROC), according to a news release from the drug developer, NextCure, Inc.¹ SIM0505 is an investigational, next-generation antibody-drug conjugate (ADC) that targets CDH6 and possesses a proprietary topoisomerase 1 payload.

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.¹ SIM0505 utilizes a proprietary topoisomerase 1 inhibitor payload and is engineered for broad anti-tumor activity, rapid systemic clearance, and an improved therapeutic window compared with earlier ADC platforms.^1,2

What data support the development of SIM0505 in CDH6-expressing tumors?

While clinical efficacy data in humans have not yet been formally released, 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 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in June.

“Securing fast track designation for SIM0505 validates the urgent, unmet need for new treatments for [PROC] and enables us to work more closely with FDA to accelerate development. We believe this designation will help to streamline and de-risk development through proactive and ongoing engagement with FDA,” stated Michael Richman, president and chief executive officer of NextCure, in the press release.¹ “We are committed to bringing SIM0505 to patients as quickly as possible and we plan to initiate dose optimization in [patients with] ovarian cancer in the second quarter of 2026. In addition, we look forward to presenting phase 1 data on the program at the upcoming 2026 American Society of Clinical Oncology conference.”

How is the SIM0505 phase 1 clinical trial structured?

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.² 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. They also have at least 1 evaluable lesion per RECIST v1.1 guidelines. For the PROC-specific cohort, patients must have high-grade serous or endometrioid ovarian cancer, as well as primary peritoneal cancer or fallopian tube cancer. Exclusion criteria include symptomatic central nervous system metastases, a history of non-infectious pneumonitis requiring steroids, any active infection that requires systemic therapy via intravenous infusion within 2 weeks of beginning study treatment, or bowel obstruction within 3 months prior to the first dose.

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.

References

1. NextCure receives fast track designation for SIM0505 (CDH6 ADC) in ovarian cancer. News release. NextCure, Inc. April 7, 2026. Accessed April 8, 2026. https://tinyurl.com/39uh9nfd
2. A phase I study of SIM0505 in participants with advanced solid tumors. ClinicalTrials.gov. Updated January 29, 2026. Accessed April 8, 2026. https://tinyurl.com/5xxnp2be