U.S. FDA Grants Orphan Drug Designation to Adcentrx Therapeutics' ADRX-0405 STEAP1 ADC for Gastric Cancer

• Orphan drug designation highlights the potential for ADRX-0405 to address the high unmet need in gastric cancer

SAN DIEGO, July 8, 2025 /PRNewswire/ -- Adcentrx Therapeutics ("Adcentrx"), a clinical-stage biotechnology company redefining Antibody-Drug Conjugate (ADC) therapies for cancer treatment and other life-threatening diseases, today announced that the U.S. Food and Drug Administration (FDA) has granted orphan drug designation to ADRX-0405, for the treatment of patients with gastric cancer.

ADRX-0405 is a STEAP1 ADC being evaluated in the Phase 1a portion of an ongoing Phase 1a/b clinical trial (NCT06710379) for the treatment of select advanced solid tumors, including metastatic castration resistant prostate cancer, gastric cancer, and non-small cell lung cancer. While STEAP1 is primarily associated with prostate cancer, there is a meaningful amount of target expression in gastric cancer, making this a potential indication of interest for future clinical development.

"Receiving orphan drug designation from FDA is a notable milestone for Adcentrx and reinforces the potential for ADRX-0405 to improve the lives of patients with gastric cancer," said Hui Li, Ph.D., Founder and Chief Executive Officer of Adcentrx. "We are encouraged by the progress of our Phase 1a trial and look forward to further evaluating the safety, tolerability and anti-tumor activity of ADRX-0405 in gastric and other cancers."

Gastric cancer, or stomach cancer, is a serious malignancy that develops in the stomach lining and is often diagnosed at advanced stages. The American Cancer Society estimates there will be 30,300 new cases of gastric cancer in the U.S. in 2025, meeting FDA's criteria for a rare disease. The orphan drug designation is a program designed to stimulate the development of treatments for rare diseases, defined as conditions affecting fewer than 200,000 people in the U.S. Benefits of this designation include access to grant funding and scientific assistance, tax credits for qualified clinical trials, waiver of Prescription Drug User Fee Act (PDUFA) application fees, and the potential for seven years of market exclusivity following regulatory approval.

About ADRX-0405
ADRX-0405 is a clinical-stage next-generation ADC targeting six-transmembrane epithelial antigen of the prostate 1 (STEAP1), a cell surface protein that is upregulated in prostate cancer and certain other cancers with limited expression in normal healthy tissue. The ADC is composed of a humanized IgG1 antibody coupled with a novel topoisomerase inhibitor linker-payload through Adcentrx's innovative i-Conjugation® technology platform – a core component in the design of the company's ADCs. The platform utilizes a cleavable linker and stable conjugation chemistry to enhance payload delivery. This novel technology enables a highly stable ADC with a drug-antibody ratio of eight (DAR 8) to maximize payload delivery to solid tumors. ADRX-0405 preclinical studies have demonstrated its favorable pharmacokinetics, safety profile, and significant efficacy across multiple animal tumor models. ADRX-0405 is currently being evaluated in a Phase 1a/b clinical trial.

For more information about the ADRX-0405 Phase 1a/b clinical trial, please refer to the Study ID NCT06710379 on ClinicalTrials.gov.

About Adcentrx Therapeutics
Adcentrx is a biotechnology company focused on accelerating breakthroughs in protein conjugate therapeutic development for cancer and other life-threatening diseases. Adcentrx has pioneered the development of an ADC technology platform addressing key components of protein conjugate design to solve challenges typically seen in ADCs. Adcentrx is developing a robust pipeline including two clinical-stage ADCs and multiple preclinical ADCs, all with first-in-class and best-in-class potential.

For more information about Adcentrx and its innovative ADC technologies, please visit https://adcentrx.com.

Contact Information:
Investor Relations
[email protected] 

SOURCE Adcentrx Therapeutics