RNAi Approval for FCS Sets New CMC Bar for Oligonucleotide Injectables

Arrowhead Pharmaceuticals secured FDA approval for REDEMPLO (plozasiran) on November 18, 2025, adding a subcutaneous RNAi therapeutic to the rare metabolic disease landscape and signaling to manufacturers and CDMOs that oligonucleotide injectable programs are maturing into a defined regulatory category with increasingly codified CMC and cold-chain expectations.

REDEMPLO is an APOC-III-directed small interfering RNA indicated, alongside a low-fat diet, to reduce triglycerides in adults with familial chylomicronemia syndrome (FCS), a rare genetic disorder impairing fat metabolism. The product is administered via subcutaneous injection once every three months, a quarterly dosing interval that carries direct implications for fill-finish scheduling, container closure integrity, and distribution logistics for any CDMO or sponsor managing a comparable injectable biologic.

The pivotal approval rested on a single randomized, placebo-controlled, double-blinded trial (Trial 1; NCT05089084) enrolling 75 adult patients with genetically or clinically confirmed FCS and fasting triglyceride levels at or above 880 mg/dL. The trial ran across 54 sites in 20 countries spanning North America, Europe, Australia, Asia, and South America, with only 9 of the 75 patients enrolled at US sites. Patients received REDEMPLO 25 mg or placebo subcutaneously every three months over a 12-month treatment period, following a stabilization phase requiring a diet of no more than 20 grams of fat per day. The primary endpoint was percent change in triglycerides from baseline to Month 10. Safety assessment drew on additional trials in patients with hypertriglyceridemia beyond the core FCS cohort.

For QA directors and regulatory affairs leads tracking the RNAi therapeutic class, the trial's multinational footprint and the product's quarterly subcutaneous administration profile underscore the process validation and sterility assurance demands that accompany this modality. Plant heads at facilities handling oligonucleotide or injectable biologic programs should treat this approval as a reference point for the CMC documentation and cold-chain infrastructure FDA expects as this class scales.

Source: FDA Drug Trials Snapshots: REDEMPLO, published April 28, 2026, based on original approval data from November 18, 2025. Full prescribing information should be consulted for all approved conditions of use.