PFS Nearly Doubles with Faridoxorubicin Treatment

In brief · summary, not quotable

Faridoxorubicin shows median PFS of 11.4 months in salivary gland cancer, nearly double historical benchmarks of 6-6.7 months.

vs expectations: ahead

Median PFS in SGC efficacy subset 11.4 months (prior 6-6.7 months (historical benchmark))
95% Confidence Interval for PFS 7 months, not reached
Patients in SGC efficacy subset 32
Tumor to plasma concentration ratio of doxorubicin 100:1
Total SGC patients enrolled 51
Duration of partial/minor responses 18.7-72 weeks

Full announcement

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Faridoxorubicin Treatment Results in Near Doubling of Progression-Free Survival and Clinically Meaningful Tumor Shrinkage in Most Patients with Salivary Gland Cancers

Durability of faridoxorubicin (AVA6000) activity results from the continued release of doxorubicin by fibroblast activation protein (FAP) demonstrated beyond 10 cycles of therapy

FAPI-PET imaging data indicate prolonged expression of FAP despite deep tumor responses in multiple patients

LONDON and PHILADELPHIA – October 26, 2026 – Avacta Therapeutics (AIM: AVCT, “the Company”, “Avacta”), a life sciences company developing innovative, targeted oncology drugs, today announces the presentation of updated data from the ongoing Phase 1a/1b trial of faridoxorubicin (AVA6000) reporting a median progression-free survival (PFS) of 11.4 months in a defined subset of patients with salivary gland cancer (SGC), compared with published historical benchmarks of 6-6.7 months. Meaningful tumor shrinkage was also observed in the patient population.

In the SGC efficacy subset (n=32), the observed median PFS of 11.4 months (95% confidence interval (CI): 7 months, not reached), represents a near doubling compared with historical benchmarks. These benchmarks are based on multiple studies of both cytotoxic regimens and targeted therapy in the earlier lines of therapy, expected to be most similar to the SGC efficacy subset (reviewed in Kanno, et al. 2025).

FAP inhibitor-positron emission tomography (FAPI-PET) imaging data and corresponding pharmacokinetic (PK) data indicate sustained FAP expression over time in patients that is associated with prolonged release of doxorubicin beyond 10 cycles of therapy. Recent preclinical platform data suggest this persistent release of payload is due to the recruitment of FAP+ fibroblasts to the tumor over the course of pre		CISION® therapy.
Faridoxorubicin is the Company’s first-generation pre		CISION® peptide-drug conjugate (PDC) delivering a doxorubicin payload directly to the tumor. Data from the trial in patients with FAP-positive solid tumors are being presented at the European Society for Medical Oncology (ESMO) Congress in Madrid, held between 23-27 October 2026.
Christina Coughlin, CEO of Avacta, commented:
“Our two datasets presented at ESMO demonstrate that our pre	CISION® platform is capable of delivering highly potent payloads to tumors over prolonged periods with sustained antitumor activity observed in patients and preclinical models. This activity occurs without the toxicity that limits the effectiveness of antibody-drug conjugates (ADCs) and their payloads, significantly widening the therapeutic index. Our first significant PFS results showing clinically meaningful progression-free intervals and tumor shrinkage in many patients support that the pre	CISION® platform can significantly improve outcomes for patients with cancer with the necessary durability.
“Importantly, new preclinical data presented at ESMO on Friday with FAP-Exd (AVA6103), the Company’s first Next-Generation pre	CISION® controlled-release PDC, demonstrate the mechanism of these findings, namely that treated tumors recruit new FAP+ fibroblasts, enhancing the capacity of the tumor to continue to cleave the pre	CISION medicines over time.
“This is further evidence that the effect of pre		CISION® PDCs can persist even as tumors shrink, an exciting differentiator compared with ADCs and first-generation PDCs, where antigen loss is thought to contribute to the question of durability. We look forward to presenting data on tumor pharmacokinetics (PK) and durability of cleavage for our lead candidate AVA6103 in late 2026 and the first efficacy data in H1 2027.”

Alan Ho, MD, PhD, Chief, Head and Neck Oncology Service, Memorial Sloan Kettering Cancer Center, New York and Senior Author of the ESMO Presentation commented,

“These are promising results with faridoxorubicin in patients with salivary gland cancers, highlighted by evidence of disease control in this rare set of diseases for which effective therapies are lacking. Evidence of enhanced FAP expression in the FAPI-PET data is unique pharmacodynamic data.”

Phase 1a/1b Trial of Faridoxorubicin (AVA6000)

The faridoxorubicin (AVA6000) Phase 1a dose escalation enrolled patients with a diagnosis of cancers frequently noted as FAP-positive. Three indications were selected for the Phase 1b expansion: SGC, soft tissue sarcoma (STS), and triple-negative breast cancer (TNBC). Data sets for STS and TNBC continue to mature.

Endpoints include safety, PK and preliminary efficacy. AVA6000 is administered as an infusion every three weeks (Q3W) or every two weeks (Q2W). A total of 51 patients with SGC were enrolled across all doses and cohorts, with any prior therapy. In the reported set of 32 patients with SGC treated at doses of 310 mg/m2 and above, patients with rare histologies and more extensive prior therapy were excluded from this analysis set. The data cutoff reported here was October 5, 2026.

Faridoxorubicin (AVA6000) was well-tolerated in this set of patients with SGC (n=32) and resulted in prolonged median PFS of 11.4 months (95% CI: 7 months, not reached), exceeding benchmarks in the 1L and 2L setting by nearly two-fold across both cytotoxic chemotherapy and targeted therapy (median 6-6.7 months, Kanno et al. 2025). Median OS in this population has not been reached.
Multiple partial (n=3) and minor responses (n=6) were observed in the reported SGC dataset with a range of duration (18.7-72 weeks).
Biopsy data show a significant concentration of tumor to plasma of released doxorubicin of 100:1, resulting in tumor reductions even at low levels of FAP expression (1+).
FAPI-PET imaging and FAP IHC data indicate that FAP expression in tumors does not diminish over time during treatment with faridoxorubicin in multiple tumor types even in the setting of tumor response
Plasma PK studies out to 12 cycles of therapy show that cleavage of faridoxorubicin to peptide and doxorubicin by FAP is stable over time, indicating persistent FAP activity

in tumors.

Details of the ESMO presentation

A Phase 1a/1b trial of FAP-Dox (AVA6000), a Fibroblast Activation Protein (FAP)-released and tumor microenvironment (TME)-targeted doxorubicin peptide drug conjugate in patients with salivary gland cancers

Authors: Renata Ferrarotto, Robert Metcalf, Steph A. Pang, William D. Tap, et. al, Alan L. Ho

Poster number: 1549P

Time: Monday October 26, 12:00-12:45pm CET

The poster can be found on Avacta’s website here.

Kanno M, et al. Palliative systemic therapy for locally advanced or metastatic salivary duct carcinoma: A comprehensive review. Cancer Treat Rev. 2025;139:102993. doi: 10.1016/j.ctrv.2025.102993

Ho has financial interests related to Avacta Therapeutics.

Enhertu® (trastuzumab deruxtecan; T-DXd) is a protease cleavable-linker ADC, approved for both breast cancer and gastric cancer indications (an AstraZeneca/Daiichi Sankyo product). Enhertu® is a registered trademark of Daiichi Sankyo Company, Limited and AstraZeneca.

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 in a small molecule format to provide unique benefits over traditional antibody drug conjugates (ADC), 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 AVA6103, a Next Generation FAP-enabled controlled release pre	CISION® version of exatecan that delivers the payload directly in the tumor with limited peripheral blood exposure and is currently in clinical development as a treatment for tumor types sensitive to exatecan including cervical cancer, HR+ breast cancer, small cell lung cancer, gastric cancer, colorectal cancer and pancreatic cancer.

About FAP-Exd (AVA6103)

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