Adcentrx Therapeutics Receives FDA Orphan Drug Designation for ADRX‑0405 in Gastric Cancer
Wednesday, July 09, 2025
Adcentrx Therapeutics has received orphan drug designation from the U.S. Food and Drug Administration (FDA) for its investigational treatment ADRX‑0405.
ADRX-0405 is a next-generation ADC targeting six-transmembrane epithelial antigen of the prostate 1 (STEAP1), a protein commonly overexpressed in prostate and some other cancers. Normal healthy tissues express the protein at limited levels, allowing for more targeted treatment. The therapy consists of a humanised IgG1 antibody linked to a novel topoisomerase inhibitor payload. This linkage is enabled through Adcentrx’s proprietary i-Conjugation® technology, which uses a cleavable linker and stable conjugation method to improve drug delivery.
The designation applies to the treatment of gastric cancer, a rare and often late-diagnosed disease.
ADRX-0405 is a STEAP1-targeting ADC currently under evaluation in the Phase 1a portion of an ongoing Phase 1a/b clinical trial (NCT06710379). The trial includes patients with advanced solid tumours such as metastatic castration-resistant prostate cancer, non-small cell lung cancer, and gastric cancer. Although STEAP1 is commonly linked to prostate cancer, the target is also present in notable levels in gastric cancer tissues, making it a viable focus for clinical development.
The FDA’s orphan drug designation is granted to therapies intended for the treatment of rare diseases—defined in the United States as those affecting fewer than 200,000 people. Gastric cancer meets this criterion, with the American Cancer Society estimating approximately 30,300 new cases expected in 2025. The designation offers various incentives to developers, including eligibility for research grants, tax credits for clinical trials, exemption from certain FDA fees, and potential seven-year market exclusivity upon regulatory approval.
The ADC is designed with a high drug-antibody ratio (DAR 8), allowing for enhanced delivery of the therapeutic payload to tumour cells. Preclinical studies have shown encouraging results, including favourable pharmacokinetics, safety, and efficacy across various tumour models. ADRX-0405 is now undergoing clinical evaluation to assess its safety, tolerability, and anti-tumour activity in multiple cancer types, including gastric cancer.
This development marks a step forward in expanding treatment options for patients with rare and difficult-to-treat cancers.
Source: adcentrx.com
