Thymus decreased in size from decreased cellularity in rats and dogs
“Other target organs of toxicity in both rats and dogs were liver (centrilobular necrosis, congestion and vacuolation), lungs (increased alveolar macrophages and inflammation) and thymus (decrease in size as a result of decreased cellularity).”
✓ VerifiedFDA pharmacology/toxicology review, p. 22Source ↗
Biodistribution & persistence
Low CNS levels; selective association with melanin-containing eye tissues in rat QWBA
“Low radioactivity concentrations were documented in central nervous system tissues (cerebellum, cerebrum, medulla, and spinal cord). Low levels of [14C]MYK-461-derived radioactivity were selectively associated with melanin-containing tissues of the eye”
✓ VerifiedFDA pharmacology/toxicology review, p. 101Source ↗
Modality-specific risk
Exaggerated pharmacology: heart failure with narrow NOAEL-to-lethal-dose margin (4-fold rat, 2.5-fold dog)
“Both rat and dog studies show that mavacamten has a narrow separation (4-fold in rats and 2.5-fold in dogs) between the NOAEL and the dose that caused heart failure and mortality, indicative of a narrow therapeutic window.”
✓ VerifiedFDA pharmacology/toxicology review, p. 4Source ↗