Avacta Therapeutics (LSE:AVCT) has reported updated Phase 1a/1b clinical trial results for faridoxorubicin (AVA6000), showing median progression-free survival (PFS) of 11.4 months in a selected group of 32 patients with salivary gland cancer.
The results, presented at the European Society for Medical Oncology (ESMO) Congress in Madrid, compare with published historical median PFS benchmarks of 6 to 6.7 months for earlier-line treatments.
The company also reported three partial tumour responses and six minor responses among the 32 patients included in the efficacy analysis, with response durations ranging from 18.7 to 72 weeks.
Avacta said additional imaging and pharmacokinetic data indicated continued release of the chemotherapy agent doxorubicin within tumours beyond 10 treatment cycles.
The findings are from an ongoing early-stage clinical trial, and the comparison with historical treatment outcomes is not based on a randomised control group.
AVA6000 Records Median Progression-Free Survival of 11.4 Months
Avacta’s latest analysis included 32 patients with salivary gland cancer who received faridoxorubicin at doses of at least 310 mg/m².
The group was selected from 51 patients with salivary gland cancer enrolled across the Phase 1a/1b trial, with certain rare cancer subtypes and patients who had received more extensive prior treatment excluded from the reported efficacy analysis.
At the data cutoff of 5 October 2026, median progression-free survival in the selected population was 11.4 months, with a 95% confidence interval ranging from seven months to an upper limit that had not been reached.
The company compared this result with historical median PFS figures of 6 to 6.7 months reported in published studies of chemotherapy and targeted treatments used in first- and second-line settings.
These historical comparisons provide context but do not establish that AVA6000 is more effective than existing treatments, as the trial did not directly compare patients receiving faridoxorubicin with a concurrent control group.
Median overall survival had not been reached at the October data cutoff.
Avacta described the treatment as well tolerated within the reported patient subset, although the announcement did not provide detailed adverse-event rates.
Nine Patients Show Partial or Minor Tumour Responses
Within the 32-patient efficacy population, Avacta reported three partial responses and six minor responses.
The observed responses lasted between 18.7 and 72 weeks.
The company said the results provide evidence of antitumour activity in patients with salivary gland cancers, a group of malignancies included in the trial because of their potential expression of fibroblast activation protein (FAP).
Faridoxorubicin is designed to deliver doxorubicin, an established chemotherapy agent, through Avacta’s pre|CISION peptide-drug conjugate technology.
The treatment is intended to release doxorubicin in the tumour microenvironment through the activity of FAP, an enzyme associated with certain tumour tissues.
The ongoing trial is assessing safety, pharmacokinetics and preliminary efficacy in patients with FAP-positive solid tumours.
AVA6000 is administered by intravenous infusion either every two weeks or every three weeks, depending on the treatment schedule.
In addition to salivary gland cancer, the Phase 1b expansion includes patients with soft tissue sarcoma and triple-negative breast cancer.
Avacta said data from the latter two cancer groups are continuing to mature.
Imaging Data Indicate Continued FAP Activity During Treatment
Avacta also presented findings from FAP inhibitor positron emission tomography (FAPI-PET) imaging and pharmacokinetic studies examining the activity of faridoxorubicin over repeated treatment cycles.
According to the company, imaging and tumour tissue analysis indicated that FAP expression was maintained over time in multiple tumour types, including in patients experiencing tumour responses.
Plasma pharmacokinetic measurements extending to 12 treatment cycles showed continued cleavage of faridoxorubicin into its peptide component and doxorubicin.
Avacta said these findings indicate that FAP-mediated drug release can persist during prolonged treatment.
Tumour biopsy data also showed a reported 100:1 concentration ratio of released doxorubicin in tumour tissue relative to plasma.
The company reported tumour reductions in patients whose samples showed relatively low FAP expression, classified as 1+.
These observations form part of Avacta’s investigation into whether its drug delivery platform can maintain chemotherapy exposure within tumours over multiple treatment cycles.
Preclinical Findings Support Further Investigation of Drug Release Mechanism
Alongside the clinical findings, Avacta referred to preclinical data from its next-generation drug candidate, FAP-Exd (AVA6103), which were also presented at ESMO.
The preclinical research suggests that treatment may lead to the recruitment of additional FAP-positive fibroblasts into tumour tissue.
Avacta believes this process could contribute to sustained drug activation as treatment continues, including when tumours decrease in size.
The company said the findings may help explain the continued release of doxorubicin observed in the AVA6000 clinical trial.
However, the proposed mechanism is supported by preclinical research and requires further evaluation to establish its clinical relevance.
AVA6103 is a next-generation pre|CISION peptide-drug conjugate designed to use FAP-mediated activation to release its therapeutic payload.
Avacta expects to present additional tumour pharmacokinetic and drug-release data for AVA6103 in late 2026, followed by initial efficacy data during the first half of 2027.
Avacta and Clinical Investigators Comment on ESMO Findings
Christina Coughlin, Chief Executive Officer of Avacta, said the updated clinical and preclinical datasets support the company’s research into sustained delivery of chemotherapy agents within tumour tissue.
Management believes the findings provide evidence that the pre|CISION platform can maintain drug activation over prolonged treatment periods.
The company also considers the data relevant to its development of AVA6103, which is intended to build on the drug delivery approach used in faridoxorubicin.
Alan Ho, Chief of the Head and Neck Oncology Service at Memorial Sloan Kettering Cancer Center in New York and senior author of the ESMO presentation, highlighted the disease-control observations in patients with salivary gland cancers.
He also identified the FAPI-PET imaging findings as relevant to understanding FAP expression during treatment.
The company has not announced a change to the clinical development programme for AVA6000 or provided a timetable for any potential regulatory submission.
Further Clinical Data Expected From Avacta’s Oncology Pipeline
Avacta is continuing its Phase 1a/1b evaluation of faridoxorubicin, with additional data from patients with soft tissue sarcoma and triple-negative breast cancer still being collected.
The company is also progressing AVA6103 as part of its next-generation pre|CISION development programme.
Its planned milestones include further pharmacokinetic and drug-release findings for AVA6103 before the end of 2026 and initial efficacy results in the first half of 2027.
The latest AVA6000 findings provide preliminary clinical evidence of antitumour activity and progression-free survival outcomes in a selected salivary gland cancer population.
Further clinical investigation will be needed to establish the treatment’s efficacy, safety profile and comparative performance against existing therapies.
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