BYM338 vs FS315
Head-to-head comparison of BYM338 (Bimagrumab (BYM338)) and FS315 (Follistatin-315 (FS315)) — benefits, dosing, side effects, research data, and where to buy.
| Property | BYM338 | FS315 |
|---|---|---|
| Category | Muscle & Performance | Muscle & Performance |
| Full Name | Bimagrumab (BYM338) | Follistatin-315 (FS315) |
| Molecular Weight | ~148 kDa | ~40 kDa |
| Half-Life | ~2-3 weeks | N/A; depends on construct/delivery |
| Amino Acids | N/A | 315 |
| Typical Dose | 10-30 mg/kg IV in trials | Research-only; no standardized human dose |
| Route | Intravenous | Intramuscular / research expression systems |
| Purity | ≥98% | ≥98% |
| Studies Count | 140 | 95 |
| Research Status | Clinical | Pre-clinical |
BYM338 Benefits
- ✓increased lean mass
- ✓functional strength support
- ✓reduced muscle wasting
- ✓metabolic body-composition shift
FS315 Benefits
- ✓activin neutralization
- ✓muscle growth signaling
- ✓anti-catabolic support
- ✓tissue repair modulation
BYM338 Dosing
IV infusion|10-30 mg/kg per study cycle|repeat every 4-12 weeks
FS315 Dosing
Research-only recombinant/protein-expression studies|no standardized clinical dose|route varies by platform
BYM338 Side Effects
- ⚠muscle cramps
- ⚠diarrhea/nausea
- ⚠infusion reactions
FS315 Side Effects
- ⚠off-target endocrine effects
- ⚠immune response risk
- ⚠fluid balance changes
Research Overview
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.
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.
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