Multiple confirmed partial and minor responses observed in patients with SGC

Continuing very good safety profile, with removal of the lifetime maximum doxorubicin limit based on highly favorable cardiac safety

LONDON and PHILADELPHIA, June 01, 2026 (GLOBE NEWSWIRE) -- Avacta Therapeutics (AIM: AVCT, "the Company", "Avacta"), a clinical stage biopharmaceutical company developing pre|CISION^®, a tumor-activated oncology delivery platform, today released updated Phase 1a/1b and  pharmacokinetics (PK), safety, toxicity and preliminary efficacy data with faridoxorubicin (AVA6000, pre|CISION^®-enabled doxorubicin) at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago.

Christina Coughlin, CEO of Avacta, commented:

"Today's data further underscores our confidence in both our Gen One product faridoxorubicin (AVA6000) and our pre|CISION^® technology to significantly improve treatment options for cancer patients.

"We are particularly encouraged by signs of efficacy in patients with salivary gland cancers (SGC and the consistency of these data from Phase 1a and 1b support the potential for this agent to move to later stage trials. The excellent safety profile was further demonstrated by the absence of severe cardiac toxicity and lifting of the lifetime maximum, following careful analysis of drug concentration versus effect on the heart.

"We look forward to presenting further data updates from this trial later in June, at the BIO International Convention."

Faridoxorubicin demonstrates favorable safety and consistent efficacy in Phase 1a and the Phase 1b SGC expansion cohort: At the recommended dose for expansion (RDE) of 310 mg/m², faridoxorubicin (AVA6000) demonstrated a safety profile consistent with that seen earlier during Phase 1a dose escalation, when comparing grade 3/4 adverse events. The rates of toxicities remain lower than those historically observed with conventional doxorubicin, despite the RDE representing a dose level that is nearly three times the maximum tolerated dose of conventional doxorubicin level (75 mg/m²).

Efficacy among patients in the SGC expansion cohort also remained consistent, with multiple confirmed responses (four partial responses and nine minor responses observed among 38 evaluable patients). The disease control rate remains consistent at 92% (35/38 with best response of stable disease or response).  Nine patients are continuing treatment, and a further 11 patients remain in follow up for disease progression.

PK and exposure-response data lead to lifting of lifetime maximum exposure: Active doxorubicin is released following dosing with faridoxorubicin, as is cleaved from the inert drug by the FAP enzyme in the tumor microenvironment (TME). Only a small fraction of the active payload subsequently enters the circulation and reaches other organs, including the heart, with a delay and at lower concentrations. This contrasts with the profile seen with conventional doxorubicin dosed intravenously, which delivers high systemic concentrations from the outset. Here, released doxorubicin is rapidly distributed, and eliminated more slowly, consistent with the known PK of conventional doxorubicin.

Preliminary Population PK (PopPK) modeling demonstrates that the sharp systemic C_max peaks, which are typical with conventional doxorubicin dosing, are eliminated with AVA6000. AVA6000 dosing results in higher clearance and larger central volume of distribution for released doxorubicin, compared with conventional doxorubicin. This shows that released doxorubicin enters plasma gradually following FAP-mediated cleavage in the TME.

There were no severe cardiac toxicity events reported and only minimal changes in left ventricular function (as measured by left ventricular ejection fraction, LVEF) observed in the 111 patients dosed to date, even with a subset of patients having reached the (protocol-defined) lifetime maximum exposure of 550 mg/m². Only four patients (<4%) reported significant reductions in LVEF and no cardiomyopathy events of any grade were observed.

Due to limited evidence of cardiac toxicity, an exposure-response analysis was conducted to assess the relationship between exposure to released doxorubicin and changes in LVEF on a per-patient basis. This analysis found no meaningful relationship between the LVEF changes and released doxorubicin exposure, suggesting that the cardiac toxicity observed with conventional dosing of doxorubicin is not observed with released doxorubicin from faridoxorubicin. This supported removal of the lifetime maximum limit of dosing. The Company received Health Authority agreement with this conclusion and hence the limit was removed from the study protocol earlier this year.

The study continues to enroll patients and Avacta plans to present further data on the AVA6000 program at BIO International Convention, taking place June 22-25, 2026 in San Diego, CA, USA.

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. 

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