Biopharmaceutical company Avacta Group PLC (AIM: AVCT) announced on Monday that it has presented updated clinical data from its Phase 1a/1b trial of AVA6000, its pre|CISION-enabled form of doxorubicin, highlighting encouraging early efficacy and a favourable safety profile in patients with salivary gland cancer (SGC) at the 2026 American Society of Clinical Oncology Annual Meeting in Chicago.

The latest results showed multiple confirmed responses among patients in the SGC expansion cohort treated at the recommended dose for expansion of 310 mg/m². Of 38 evaluable patients, four achieved confirmed partial responses and nine recorded minor responses, while the disease control rate remained at 92%, with 35 patients achieving either stable disease or a clinical response. Nine patients continue to receive treatment and a further 11 remain under follow-up for disease progression.

Avacta reported that AVA6000 continues to demonstrate a safety profile consistent with earlier findings from the Phase 1a dose-escalation study. Rates of Grade 3 and Grade 4 adverse events remained lower than those historically associated with conventional doxorubicin, despite the recommended expansion dose being almost three times higher than the maximum tolerated dose of standard doxorubicin.

New pharmacokinetic and exposure-response analyses further reinforced the differentiated profile of AVA6000. The data showed that active doxorubicin is released within the tumour microenvironment through cleavage by fibroblast activation protein (FAP), resulting in lower and delayed systemic exposure compared with conventional intravenous doxorubicin. Preliminary population pharmacokinetic modelling indicated that the high systemic peak concentrations typically associated with standard doxorubicin are largely eliminated with AVA6000.

The company also highlighted continued evidence of favourable cardiac safety. Among 111 patients treated to date, no severe cardiac toxicity events or cardiomyopathy cases have been reported, while only four patients experienced significant reductions in left ventricular ejection fraction. Importantly, no meaningful relationship was identified between exposure to released doxorubicin and changes in cardiac function.

Based on these findings, Avacta received agreement from health authorities to remove the protocol-defined lifetime maximum exposure limit of 550 mg/m² earlier this year, allowing continued dosing beyond levels traditionally associated with cumulative cardiac toxicity from conventional doxorubicin.

The study remains ongoing, with patient enrolment continuing. Avacta said it expects to provide additional updates on the AVA6000 programme at the BIO International Convention, taking place from 22 to 25 June 2026 in San Diego, California.

AVA6000 is the lead programme within Avacta's proprietary pre|CISION platform, which is designed to selectively release highly potent cancer therapies within the tumour microenvironment while reducing exposure to healthy tissues. The company believes the approach has the potential to improve the therapeutic index of established oncology agents by enhancing efficacy while limiting systemic toxicity.