AVA6000

What is AVA6000?

AVA6000 is Avacta Therapeutics' investigational peptide-drug conjugate (PDC) consisting of doxorubicin masked by a fibroblast activation protein (FAP)-cleavable peptide linker. FAP is a serine protease expressed on cancer-associated fibroblasts in the tumor microenvironment, with elevated expression in many solid tumors (sarcoma, breast, pancreatic, others) but minimal expression in healthy tissue. The pre|CISION platform exploits this differential expression: the doxorubicin is biologically inactive until the peptide linker is cleaved by FAP at the tumor site, locally releasing active drug. The strategy aims to deliver the established cytotoxic doxorubicin to tumors while sparing systemic exposure that drives the cardiotoxicity, myelosuppression, and other off-target effects that limit standard doxorubicin therapy. AVA6000 is in Phase 1 ALS-6000-001 trial across multiple FAP-expressing solid tumor types.

What AVA6000 Is Investigated For

AVA6000 is Avacta's lead peptide-drug conjugate using its pre|CISION platform — FAP-activated tumor-selective delivery of doxorubicin. The mechanistic premise is elegant: doxorubicin is highly effective but limited by cardiotoxicity at lifetime cumulative doses; masking it with a FAP-cleavable peptide linker should produce tumor-selective release that reduces systemic exposure and the associated cardiotoxicity. The strongest evidence is preclinical: animal models demonstrated tumor-selective doxorubicin release and improved therapeutic index. Phase 1 ALS-6000-001 in FAP-expressing solid tumors began in 2022–2023, with preliminary clinical activity reported in conference proceedings through 2024–2026. The honest caveats: clinical Phase 1 data is preliminary and tumor-microenvironment-activated drug platforms have historically struggled with translation (the requirement for sufficient FAP expression, tumor accessibility, and adequate peptide-bond cleavage all need to align in human cancers as they do in animal models). The platform is more notable as proof-of-concept for FAP-targeted drug delivery than as a near-term approved cancer therapy.

History & Discovery

Avacta Therapeutics developed the pre|CISION platform around FAP-activated drug delivery as a tumor-microenvironment targeting strategy. AVA6000 was selected as the lead candidate using doxorubicin — a well-characterized and well-validated cytotoxic — as the payload, with the rationale that improving doxorubicin's therapeutic index through tumor-selective delivery would be valuable in multiple FAP-expressing cancer indications. The Phase 1 FOCUS trial (NCT04969835) began in 2022 with multi-tumor enrollment across salivary gland, urothelial, ovarian, breast, and soft tissue sarcoma, and the first dose-escalation data was presented at AACR 2024 (abstract #CT188) and ESMO 2024 (abstract #646P). The International Nonproprietary Name 'faridoxorubicin' was assigned around late 2024 / early 2025 and adopted in Avacta communications by the October 2025 ESMO press release; AVA6000 remains the development code. The clinical inflection point came on December 17, 2025 when Avacta announced the Phase 1b salivary gland cancer cohort readout: across 30 evaluable patients dosed ≥250 mg/m², the disease control rate reached 90% (2 confirmed partial responses, 7 minor responses with 10–<30% tumor shrinkage), median PFS was not reached at >15 weeks median follow-up, and 13 of 19 Phase 1b patients remained on therapy at the cutoff. Critically for the platform thesis, no severe cardiac toxicity was observed at cumulative doxorubicin-equivalent doses up to 550 mg/m² — beyond the threshold at which standard doxorubicin produces clinically significant cardiotoxicity in most patients, supporting the FAP-activated delivery rationale. On February 3, 2026, Avacta announced two protocol updates: the maximum dosing limit was removed and dose-level flexibility was added to support a smooth transition to future efficacy studies. ASCO 2026 (May 29–June 2, 2026, Chicago) accepted an expanded data presentation for faridoxorubicin in salivary gland cancer. As of mid-2026, the FOCUS trial continues recruitment (estimated n=158, primary completion June 2026), with anticipated Phase 2 progression in salivary gland cancer and other FAP-expressing tumor populations. The pre|CISION platform itself has expanded beyond faridoxorubicin: AVA6103 (FAP-exatecan) is the second clinical PDC, with first patient dosed March 31, 2026 in the FOCUS-01 Phase 1 (NCT07454642), and AVA6207 (a dual-payload PDC) was introduced at Avacta's 2026 Science Day. The FAP-activated drug delivery concept has been pursued by multiple companies with varying payloads and linker designs; faridoxorubicin represents one of the most advanced clinical programs in the space, with the doxorubicin payload providing a known clinical comparator for benchmarking the platform's therapeutic-index improvement.

How It Works

Doxorubicin is a powerful chemotherapy drug but has serious side effects, especially to the heart. AVA6000 is doxorubicin attached to a 'safety lock' (a peptide) that only opens up at tumor sites — where an enzyme called FAP (found mainly on cancer-supporting cells) cuts the peptide and releases the active drug. The goal is to keep the chemotherapy benefit while reducing the side effects to healthy tissues.

AVA6000 is a peptide-drug conjugate consisting of doxorubicin linked via a peptide bond to a sequence cleavable by fibroblast activation protein alpha (FAPα). FAPα is a serine protease in the dipeptidyl peptidase family with relatively restricted expression — high on cancer-associated fibroblasts (CAFs) in many solid tumors and on activated fibroblasts at sites of tissue remodeling and fibrosis, but minimal expression in healthy adult tissues. In circulation, AVA6000 is biologically inactive (the peptide masks doxorubicin's DNA-intercalating activity). At FAP-expressing tumor sites, FAPα cleaves the peptide bond releasing free doxorubicin in the tumor microenvironment, where it can be taken up by tumor cells and produce DNA damage through topoisomerase II inhibition and intercalation. The intended pharmacokinetic profile is high tumor-to-plasma doxorubicin ratio, reducing systemic exposure responsible for cardiotoxicity and other off-target effects. Key clinical questions include: (1) Does sufficient FAP activity exist in human tumors to produce therapeutic doxorubicin levels? (2) Does the reduced systemic exposure translate to clinically meaningful cardiotoxicity reduction? (3) Are FAP-expression-positive tumors a single responsive population, or is heterogeneity within that group? Phase 1 ALS-6000-001 is designed to address these in part.

Evidence Snapshot

Research Gaps & Open Questions

What the current literature has not yet settled about AVA6000:

• 01Phase 1 efficacy data — preliminary; full publication pending.
• 02Cardiotoxicity comparison versus standard doxorubicin — the key value proposition is reduced cardiotoxicity, requiring direct comparison in larger trials.
• 03FAP expression threshold for clinical response — patient selection biomarker development is ongoing.
• 04Tumor type selection — multiple FAP-expressing tumors are being evaluated; which respond best is being clarified.
• 05Combination strategies with immunotherapy or other agents.

Forms & Administration

Intravenous infusion. Investigational. Not commercially available.

Dosing & Protocols

The ranges below reflect protocols commonly discussed in the literature and by clinicians — not a prescription. Actual dosing for any individual should be determined by a qualified healthcare provider who knows the patient.

AVA6000 is investigational and Phase 1 stage. Oncology management requires specialty care.

Timeline of Effects

Common Questions

Who AVA6000 Is NOT For

Drug & Supplement Interactions

Doxorubicin-class drug interactions apply (cardiotoxic agents, certain CYP-inducing or -inhibiting medications, etc.). Specific AVA6000 drug interactions will be characterized in clinical development.

Safety Profile

Legal Status

Regulatory status changes over time. Verify current local rules with a qualified professional.

Myths & Misconceptions