Side-by-side · Research reference

ACE-031vsThymosin α-1

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

APhase 2HUMAN-REVIEWED10/44 cited

BPhase 3HUMAN-REVIEWED8/39 cited

ACE-031

ActRIIB-Fc Fusion · Phase 2 Halted

Phase 2Highest trial stage

2011Development halted

~58.4 kDaMolecular weightReichel 2025

SQ · Weekly dosing investigated

Thymosin α-1

Immune modulator · Approved (some countries)

1.6 mgPer doseIyer 2007

Phase 3Evidence levelIyer 2007 Camerini 2001

~2 hrHalf-life

SQ · 2× weekly · 6+ months for chronic indications

01Mechanism of Action

Parameter

ACE-031

Thymosin α-1

Primary target

Myostatin, GDF11, activin A — TGF-β superfamily ligands

Toll-like receptor 9 (TLR9) + T-cell maturation pathwayCamerini 2001

Pathway

Soluble decoy receptor binds circulating myostatin/TGF-β ligands → prevents ActRIIB activation → SMAD2/3 pathway inhibition

TLR9 activation → ↑ IFN-α + IL-2 + IFN-γ → enhanced T-cell function + dendritic cell maturationIyer 2007

Downstream effect

Disinhibition of myogenic signaling, increased skeletal muscle mass and strength

Restored T-cell function, improved viral clearance, anti-tumour adjuvant effectsIyer 2007

Feedback intact?

—

Origin

Recombinant fusion protein: human ActRIIB extracellular domain + IgG1-Fc fragmentReichel 2025

Synthetic 28-AA peptide identical to natural Tα-1 isolated from thymus extractCamerini 2001

Antibody development

—

02Dosage Protocols

Parameter

ACE-031

Thymosin α-1

Clinical dosing

Weekly or biweekly SQ injections (exact doses undisclosed pre-halt)

Phase 2 DMD trial protocol not fully published.

—

Black market products

Variable purity; 12/14 tested products contained target protein plus contaminantsReichel 2025

SDS-PAGE revealed multiple protein bands; quality control absent.Reichel 2025

—

Evidence basis

Phase 2 trial discontinued — incomplete dataset

Phase 3 + approved (35+ countries as Zadaxin)Iyer 2007

Half-life

Days to weeks (Fc-fusion typical kinetics)

IgG1-Fc domain confers extended circulation time.

~2 hours plasma; tissue effect days

Duration investigated

12–24 weeks (trial cut short)

—

Standard dose (HBV/HCV)

—

1.6 mg SQ 2× weekly × 6–12 monthsIyer 2007

Frequency

—

2× weekly (Mon/Thu typical)

Lower / starter dose

—

0.8 mg per injection

Duration

—

6–12 months for chronic indications

Reconstitution

—

Sterile water for injection per vial label

Timing

—

No specific time

04Side Effects & Safety

Parameter

ACE-031

Thymosin α-1

Epistaxis (nosebleeds)

Significant incidence in Phase 2 DMD trial — primary safety signal

—

Telangiectasia

Dilated capillaries / spider veins observed

—

Vascular abnormalities

Mechanism: ActRIIB/ALK1 pathway disruption affects vascular homeostasis

—

Injection site reactions

Local erythema, induration (biologics class effect)

—

Antibody development

Potential for anti-drug antibodies (Fc-fusion proteins); incidence not reported

—

Black market contaminants

12/14 tested products contained multiple unidentified proteins alongside ACE-031Reichel 2025

—

Injection site reaction

—

Erythema, mild discomfort

GI symptoms

—

Rare nausea

Fatigue

—

Common during initial weeks

Fever / flu-like

—

Mild interferon-like response possible

Autoimmune

—

Theoretical risk; caution in active autoimmune disease

Cancer risk

—

No signal — used as adjuvant in oncology

Pregnancy / OB

—

Avoid

Absolute Contraindications

ACE-031

·History of vascular disorders (epistaxis, telangiectasia, HHT)
·Pregnancy (TGF-β pathway critical for fetal development)
·Active malignancy (myostatin inhibition may affect tumour growth)
·Use of non-pharmaceutical grade ACE-031 (contamination risk)Reichel 2025

Thymosin α-1

·Pregnancy / breastfeeding
·Hypersensitivity to peptide
·Concurrent immunosuppressant therapy (transplant patients)

Relative Contraindications

ACE-031

·Coagulation disorders or anticoagulant use (epistaxis risk)
·Hereditary hemorrhagic telangiectasia (HHT) family history
·Cardiovascular disease (vascular remodeling effects unknown)

Thymosin α-1

·Active autoimmune disease
·Severe immunocompromised state without supervision

05Administration Protocol

Parameter

ACE-031

Thymosin α-1

1. Pharmaceutical status

ACE-031 is not FDA-approved or commercially available. Phase 2 development was discontinued in 2011 due to safety concerns. Any ACE-031 on the black market is unregulated research chemical.

Add 1 mL sterile water per 1.6 mg vial → 1.6 mg/mL.

2. Black market quality

12 of 14 tested black market ACE-031 products contained the target protein but also carried multiple unidentified protein contaminants detectable by SDS-PAGE. Two products contained no ACVR2B-immunoreactive material.Reichel 2025

SQ — abdomen, thigh, or upper arm. Rotate sites.

3. Detection in sport

ACE-031 is prohibited under WADA S4.3 (Myostatin Inhibitors). Gel electrophoresis and Western blotting using ACVR2B-specific antibodies can detect the ~58.4 kDa protein in biological samples.Reichel 2025

2× weekly, e.g. Monday + Thursday.

4. Clinical trial route

Phase 2 protocol used subcutaneous injections at weekly or biweekly intervals. Exact dosing protocols remain unpublished.

Lyophilised: refrigerate. Reconstituted: refrigerate, use within 24 h.

5. Needle

—

27–31G, 4–8 mm insulin syringe.