Avacta Group Regulatory News (AVCT)

Avacta reports new pharmacology data for FAP-Exd (AVA6103)

Multiple patient-derived xenograft models with prolonged complete responses associated with sustained release of the exatecan payload within the tumor over five days

LONDON and PHILADELPHIA - December 18, 2025 - Avacta Therapeutics (AIM: AVCT), a clinical stage biopharmaceutical company developing pre|CISION®, a tumor-activated oncology delivery platform, today announced new pharmacology data with its second asset, FAP-Exd (AVA6103) which is anticipated to begin Phase 1 testing in Q1 2026.

FAP-Exd (AVA6103) is a pre|CISION® peptide drug conjugate comprised of the proprietary FAP-cleavable peptide linked to a highly potent topoisomerase I (topo I) inhibitor, a key antitumor mechanism useful in many human solid tumor types. 

Today's new data include the following observations:

· Potent tumor-specific and broad-spectrum cytotoxicity: FAP-Exd (pre|CISION exatecan) is a potent peptide drug conjugate designed to produce sustained release of active exatecan directly in the tumor via the pre|CISION bystander effect

· Sustained release mechanism in the tumor is highly effective: The sustained release mechanism produces a maximum concentration (Cmax) of released exatecan, with exposure duration of over five days in the tumor, with plasma exposure gone in two hours

· High levels of antitumor activity of FAP-Exd: Multiple patient-derived xenograft models demonstrate robust antitumor activity with deeper and more durable responses than achieved with conventional exatecan

· FAP-Exd has the potential to reach a broad patient population with high unmet need: Exatecan is the most potent topoisomerase I inhibitor that has been tested in the clinic and as a pre|CISION medicine delivers exatecan directly to the tumor with the potential to address multiple indications with high unmet need

· Faster and more robust Phase 1 development using AI: The clinical development of FAP-Exd was designed using an AI approach, querying a large database to identify those cancer indications with the highest likelihood of response to the drug through co-expression of FAP and SLFN11

Christina Coughlin MD, PhD, CEO of Avacta, commented:

"These data are key to support the clinical development of FAP-Exd (AVA6103) and the profile of this second pre|CISION medicine in the preclinical setting is tremendous. The sustained release mechanism developed by Avacta scientists results in a robust concentration of active drug in the tumor over five days with the disappearance from the bloodstream in only two hours. This is the exact profile needed to achieve better efficacy with this highly potent topo I inhibitor.

"Our AI collaboration has led to several key insights into the patient population for the FAP-Exd program and has helped to drive a smarter and faster clinical trial. We are eagerly anticipating the next steps for this exciting program in 2026."

-Ends-

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About Avacta - www.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.