Phase 1 study opening for AVA6103

Avacta announces opening of Phase 1 trial for second pipeline asset, FAP-Exd (AVA6103) a sustained-release pre|CISION® exatecan peptide-drug conjugate

Specialty U.S. oncology centers open for recruitment in Virginia and Texas

LONDON and PHILADELPHIA - March 16, 2026 - Avacta Therapeutics (AIM: AVCT, "the Company", "Avacta"), a clinical stage biopharmaceutical company developing pre|CISION®, a tumor-activated oncology delivery platform, today announced the opening of the Phase 1 trial of FAP-Exd (AVA6103), the Company's second clinical program and the first sustained-release pre|CISION® peptide drug conjugate. FAP-Exd (AVA6103) is a fibroblast activation protein (FAP)-released version of exatecan, a highly potent topoisomerase I inhibitor.

The Phase 1a dose escalation portion of the clinical trial will evaluate the safety, tumor and plasma pharmacokinetics and preliminary efficacy of AVA6103 in patients diagnosed with one of four solid tumors in the advanced setting: pancreatic cancer, cervical and vulvar cancer, gastric and gastroesophageal junction cancers and small cell lung cancer. The trial is designed to identify a dose and regimen for further clinical development.

The first patient is anticipated to enroll in the study before the end of March. Adult participants will be enrolled in the Phase 1a dose-escalation portion of the trial with parallel arms investigating two schedules of administration (every two weeks; Q2W, and every three weeks; Q3W), with preliminary safety and pharmacokinetic data anticipated in the second half of 2026.

The first two centers to open for enrollment are the Virginia Cancer Specialists (VCS) Research Institute in Fairfax, Virgina, and NEXT Oncology Specialists in Dallas, Texas.

Christina Coughlin, CEO of Avacta Therapeutics, commented:

"The opening of the first clinical sites in the Phase 1 trial of AVA6103 is an important milestone. It is notable that this program continues to move into clinical development faster than normal industry timelines. With our proprietary sustained release mechanism, we expect AVA6103 to enable greater efficacy from the exatecan payload while limiting the severe toxicities that were observed in the initial development of this payload in the clinic."

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About Avacta - https://avacta.com/

Avacta Therapeutics is a clinical-stage life sciences company expanding the reach of highly potent cancer therapies with the pre|CISION® platform. pre|CISION® is a proprietary payload delivery system based on a tumor-specific protease (fibroblast activation protein or FAP) that is designed to concentrate highly potent payloads in the tumor microenvironment while sparing normal tissues.

Our innovative pipeline consists of pre|CISION® peptide drug conjugates (PDC) or Affimer® drug conjugates (AffDC) that leverage the tumor-specific release mechanism, providing unique benefits over traditional antibody drug conjugates.

The pre|CISION® platform comprises an anticancer payload conjugated to a proprietary peptide that is a highly specific substrate for fibroblast activation protein (FAP) which is upregulated in most solid tumors compared with healthy tissues. The pre|CISION® platform harnesses this tumor specific protease to cleave pre|CISION® peptide drug conjugates and pre|CISION® antibody/Affimer® drug conjugates in the tumor microenvironment, thus releasing active payload in the tumor and reducing systemic exposure and toxicity, allowing dosing to be optimized to deliver the best outcomes for patients.