Clinical Application Scenarios
Neuromuscular Diseases
All human clinical data for FS344 come from gene therapy trials. In the Phase I/IIa trial conducted at Nationwide Children's Hospital, six patients with Becker muscular dystrophy (BMD) received bilateral quadriceps direct injections of AAV1.CMV.FS344. In Cohort 1 (3 × 10¹¹ vg/kg/leg), two patients showed improvements of 58 meters and 125 meters, respectively, in the 6-minute walk test; in Cohort 2 (6 × 10¹¹ vg/kg/leg), two patients showed improvements of 108 meters and 29 meters, respectively. Histological examination showed reduced intimal fibrosis, decreased central nucleation, and myofibril hypertrophy. No serious adverse events were observed.
The same team also conducted gene therapy evaluations in patients with sporadic inclusion body myositis (sIBM), providing an intervention pathway for this refractory disease based on the dual effects of follistatin-increasing muscle strength and reducing mononuclear cell infiltration.
Preclinical Translational Studies: In mouse models, a single intramuscular injection of AAV1-FS344 resulted in a sustained increase of over 20% in muscle mass in wild-type C57Bl/6 mice, outperforming other myostatin inhibitors such as GASP-1 and FLRG. In mdx mice (Duchenne muscular dystrophy model), the high-dose group (1.5 × 10¹² vg/kg) showed a 15-fold increase in serum follistatin, with dose-dependent improvement in muscle strength lasting over 560 days.
In non-human primate (macaque) studies, AAV1-FS344 achieved significant increases in muscle mass and strength under the control of both the muscle-specific promoter (MCK) and the universal promoter (CMV), without observing any pathological or functional changes in the reproductive system.
Sports Medicine and Body Composition Optimization: Based on the mechanism of myostatin inhibition pathway, FS344 is being used in functional medicine and sports medicine to overcome muscle growth plateaus. The target population includes advanced researchers who have completed training and nutritional optimization and are seeking further lean body mass gains. When used in combination with GLP-1 receptor agonist weight loss regimens, FS344 can counteract catabolic side effects and protect muscle mass.
It is important to clarify that the preclinical data mentioned above are based on AAV viral vector delivery-the virus continuously expresses FS344 in muscle for weeks to years, which is fundamentally different from the pharmacokinetics of direct injection of recombinant FS344 protein. The half-life of recombinant proteins is measured in hours; therefore, community injection regimens cannot replicate the durable effects of gene therapy.
Usage and Dosing Guidelines
Dosage and Route of Administration
Human pharmacokinetic data for direct injection of recombinant FS344 are almost nonexistent; all community protocols are extrapolations from animal data and theoretical deductions. Currently, there are three main protocols:
Routine 1 (Intramuscular Injection on Training Days): 50-100 mcg per injection, intramuscularly 30 minutes before training (IM), administered only on training days, discontinued on rest days. An 8-week use period followed by an 8-week withdrawal period. Injection sites include the deltoid, vastus lateralis, or gluteus medius.
Option 2 (Subcutaneous Injection Cycle): 100 mcg/day subcutaneous injection (SC) for a 10-day loading period, followed by a maintenance period of 100 mcg every other day, for a total cycle of 30 days.
Option 3 (Low-Frequency Subcutaneous): 100-300 mcg subcutaneous injection, 2-3 times per week.
Intramuscular injection is considered more effective in delivering the drug to target muscle tissue, but as a circulating protein, the injection site and effector site do not need to strictly correspond. Use a 29-31G insulin injector; the single injection volume is typically 0.05-0.2 mL.
Reconstitution Procedure: FS344 is supplied as a lyophilized powder, commonly in 1 mg vials. Reconstitution should only be performed using sterile water for injection containing 0.9% benzyl alcohol.
Standard Reconstitution Protocol: 1 mg of lyophilized powder is added to 2 mL of sterile water, resulting in a final concentration of 500 mcg/mL. At this concentration, 50 mcg corresponds to 10 units on an insulin syringe, and 100 mcg corresponds to 20 units.
Operating Procedure: Allow the lyophilized powder vial to reach room temperature for 10-15 minutes; disinfect the stopper with an alcohol swab; draw the calculated volume of antibacterial solution; insert the needle obliquely into the stopper and slowly inject the solution along the vial wall, avoiding direct contact with the powder; gently roll the vial in your palm to aid dissolution, do not shake-FS344 is a fragile protein, vigorous shaking can cause denaturation; the solution should be clear and transparent after complete dissolution. Discard if it becomes cloudy, contains particles, or discolored. The dissolution process may take 2-5 minutes.
FAQ
Q: What is the minimum order quantity?
A: The minimum order quantity is 10 vials/set.
Q: How long does it take to ship?
A: In-stock orders will be shipped within 24 hours.
Q: What purity levels can you provide?
A: Standard purity 99%.
Q: Which courier service do you use? A: You can choose from FedEx, DHL, UPS, and postal services.
Q: How long does shipping take?
A: Approximately 10-15 days.
Q: Can you provide a COA (Certificate of Account) quality inspection report and HPLC (High-Performance Computing) report?
A: Yes, all goods undergo professional testing before shipment.
Q: Do you support OEM branding?
A: OEM branding is supported, subject to minimum order quantity requirements.
Q: How is after-sales service handled?
A: After the customer signs for the goods, if it is confirmed that the quality problem is caused by our production, they can enjoy free replacement or refund. We adhere to a pragmatic and responsible service principle, actively respond to and properly handle all kinds of issues, without shirking responsibility or avoiding problems, and do our best to protect the rights and interests of our customers.
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A: We support bank transfer, Bitcoin, Transferwise, and Xoom.
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