Avacta Group Regulatory News (AVCT)

Avacta presents new comparisons of pre|CISION® payload release vs approved ADCs and AVA6207 dual payload delivery at Science Day 2026

LONDON and PHILADELPHIA - May 6, 2026 - Avacta Therapeutics (AIM: AVCT, "the Company", "Avacta"), a clinical stage biopharmaceutical company developing pre|CISION®, a tumor-activated oncology delivery platform, will today present two new developments at its Science Day 2026 event.

The Company is presenting comparative analyses of pre|CISION® payload delivery via one of its programs, AVA6103, compared with now two approved Antibody-Drug Conjugates (ADCs).It is also presenting updated in vivo studies of the dual payload delivery system in another program, AVA6207.

Christina Coughlin, CEO of Avacta, commented:

"These presentations further underline the potential of our unique pre|CISION® technology to improve treatment options for cancer patients.

"Providing data analysis of two ADCs, including Enhertu®, as part of the AVA6103 program, further demonstrates the alignment of the ADC mechanism and highlights the critical advantages of our pre|CISION® delivery directly to the tumor with higher selectivity, regardless of the ADC target.

"The data with our pre|CISION technology to deliver dual payloads has now demonstrated for the first time an efficacy advantage over single payload ADCs in a FAP-low and HER2-positive patient-derived cancer model.

"We continue to build momentum and enhance our IP - at a pace that we are confident exceeds industry norms."

AVA6103: The new data analyses in the AVA6103 program comparing pre|CISION® FAP-cleavable exatecan delivery with those of leading marketed ADCs have been extended to Datroway®, an ADC targeting the TROP2 antigen, as well as Enhertu® an ADC targeting the HER2 antigen. 

Details of these studies:

· All three of these drugs (AVA6103, Enhertu® and Datroway®) feature tumor-targeted delivery of topoisomase I inhibitors (exatecan or deruxtecan) and these comparisons are designed to address the differences in the payload delivery and control for the differences in cancer models

· The delivery kinetics of exatecan (derived from AVA6103) and deruxtecan (derived from Enhertu® or Datroway®) demonstrate more rapid tumor penetration of released exatecan from AVA6103 (Tmax of minutes, AVA6103 versus Tmax >24 hours, Enhertu® or Datroway®) and higher maximal concentration (Cmax) of released payload in the tumor with differences observed of over 1-log 

· The tumor selectivity index (TSI) is a measure of the overall exposure (area under the curve, AUC) in the tumor vs. the bloodstream (TSI = AUC[tumor/plasma]) which is at least 3 times higher with released exatecan from AVA6103 than either released deruxtecan from Enhertu® or Datroway®

· The Company is planning to publish these findings at an upcoming academic meeting and in a peer-reviewed journal

AVA6207: The in vivo data in the AVA6207 program show the dual payload delivery demonstrating prolonged deep complete responses despite tumor regrowth with the conventional cytotoxic drugs. Initial data was published at AACR 2026 last month and has been updated. 

Findings include:

· Results indicate that deep and durable complete responses are observed in the FAP-high model, HEK-FAP where tumors regrow with conventional therapy. 

· In the FAP-low/HER2-positive patient derived xenograft model of gastric cancer, durable responses with AVA6207 are observed where tumor regrowth is observed with Enhertu®. These results suggest optimal treatment with the combination is more effective in this model than the deruxtecan-based ADC. 

The investor Science Day 2026 event is being held at the Royal Society of Chemistry, Burlington House, Piccadilly, London W1J 0BA, starting at 10.30am. Attendance capacity is limited, so attendance is limited to those who have received confirmation of registration previously. The presentations will be recorded and published on the Company website in due course.

Enhertu® is a registered trademark of Daiichi Sankyo Company, Limited and AstraZeneca. Datroway® is a registered trademark of Daiichi Sankyo Company, Limited.

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For further information from Avacta, please contact:

About Avacta - https://avacta.com/

Avacta Therapeutics is a clinical-stage life sciences company expanding the reach of highly potent cancer therapies through its proprietary pre|CISION® platform. pre|CISION® is a 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. Avacta's innovative pre|CISION® peptide drug conjugates (PDC) are a novel entry to the XDC drug class, leveraging the success of antibody drug conjugates with alternative methods of delivery beyond antibodies. 

Our pre|CISION® PDCs leverage this tumor-specific release mechanism to provide unique benefits over traditional antibody drug conjugates, releasing active payload in the tumor and reducing systemic exposure and toxicity which enables dosing to be optimized to deliver the best outcomes for patients. The lead clinical program is faridoxorubicin (AVA6000), a Gen One FAP-enabled pre|CISION® version of doxorubicin that delivers the payload directly in the tumor with limited peripheral blood exposure and has demonstrated preliminary activity in tumor types sensitive to doxorubicin including salivary gland cancer and soft tissue sarcoma.