The published lipid 10p study provides a defined siRNA screening composition and mouse Factor VII silencing data. Separate regulatory studies describe tissue persistence after intramuscular administration; these results belong to different formulations and routes.
ATX-126 is identified by chemical name in the PMDA report and matches lipid 10p in Rajappan et al. The mouse siRNA screen and the regulatory vaccine studies are presented as separate evidence records.
Formulation components and molecular-weight conversion
Rajappan 2020 siRNA formulation: 58:7:33.5:1.5 mol%; total lipid:RNA approximately 30:1 by mass. The 30:1 ratio is not N/P. DMG-PEG2000 MW 2507 follows the catalog calculation convention. This is not asserted to be the Kostaive manufacturing composition.
Component mass calculator
Prefilled proportions follow the source specified above. Molecular weights and ratios are editable. Results are calculated, not measured study data. No N/P or RNA dose is inferred.
Component
MW
Molar ratio
Mass (mg)
Mass %
ATX-126
DSPC
Cholesterol
DMG-PEG2000
Formulation and particle evidence
Parameter
Reported finding
Source
Apparent pKa
6.38 in the formulated-lipid study
Rajappan 2020, Table 8
siRNA encapsulation
The study reports >90% across its tested lipid formulations
Experimental Section: siRNA Formulation into Lipid Nanoparticles
Regulatory LNP components
ATX-126, DSPC, cholesterol, PEG2000-DMG; ratio not assigned here
Lipid 10p, Tables 7–8; target-specific knockdown, not general mRNA efficacy
Mouse plasma stability
100% lipid remaining at 2 hours
Table 8; does not support a rapid-clearance claim
Short mouse tolerability study
No abnormal observations reported at 3 mg/kg siRNA
Nontargeting-siRNA LNP assessment with 72-hour observation; not chronic or human safety
Regulatory biodistribution context
Context
Finding
Boundary
ARCT-021 repeated intramuscular rabbit study
ATX-126 remained detectable in liver, spleen, muscle and ovary on Day 57; no histopathological findings of toxicological significance were reported in these tissues
PMDA PDF pp16–17, section 4.2.2; not the intravenous siRNA formulation
ATX-126 metabolism assessment
Slow turnover and prolonged tissue persistence are described
PMDA PDF pp17–19; ester groups alone do not establish rapid elimination
