FS315 vs BYM338
Head-to-head comparison of FS315 (Follistatin-315 (FS315)) and BYM338 (Bimagrumab (BYM338)) — benefits, dosing, side effects, research data, and where to buy.
| Property | FS315 | BYM338 |
|---|---|---|
| Category | Muscle & Performance | Muscle & Performance |
| Full Name | Follistatin-315 (FS315) | Bimagrumab (BYM338) |
| Molecular Weight | ~40 kDa | ~148 kDa |
| Half-Life | N/A; depends on construct/delivery | ~2-3 weeks |
| Amino Acids | 315 | N/A |
| Typical Dose | Research-only; no standardized human dose | 10-30 mg/kg IV in trials |
| Route | Intramuscular / research expression systems | Intravenous |
| Purity | ≥98% | ≥98% |
| Studies Count | 95 | 140 |
| Research Status | Pre-clinical | Clinical |
FS315 Benefits
- ✓activin neutralization
- ✓muscle growth signaling
- ✓anti-catabolic support
- ✓tissue repair modulation
BYM338 Benefits
- ✓increased lean mass
- ✓functional strength support
- ✓reduced muscle wasting
- ✓metabolic body-composition shift
FS315 Dosing
Research-only recombinant/protein-expression studies|no standardized clinical dose|route varies by platform
BYM338 Dosing
IV infusion|10-30 mg/kg per study cycle|repeat every 4-12 weeks
FS315 Side Effects
- ⚠off-target endocrine effects
- ⚠immune response risk
- ⚠fluid balance changes
BYM338 Side Effects
- ⚠muscle cramps
- ⚠diarrhea/nausea
- ⚠infusion reactions
Research Overview
FS315
Follistatin-315 is a key reference isoform in studies of muscle anabolism and reproductive/endocrine biology. In muscle research, it is relevant because it suppresses activin and can indirectly blunt myostatin pathway output.
BYM338
Clinical trials showed meaningful increases in lean mass, with mixed functional outcomes depending on population and endpoint. The antibody remains one of the best-documented receptor-blocking approaches to muscle anabolism in humans.
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