US Hereditary Angioedema Launch Readiness

Lanadelumab (Takhzyro) holds roughly 45% of US HAE prophylaxis share with high KOL loyalty and very low breakthrough-attack rates in stable patients — a population that is structurally hard to switch. Berotralstat (Orladeyo), the once-daily oral entrant, has instead grown the market by converting never-prophylaxed patients, reaching ~20% share since 2020. Of the ~8,000-9,000 US HAE patients, only 35-40% currently receive any prophylaxis; an estimated 2,500-4,000 patients meet prophylaxis criteria (≥3 attacks/year or a laryngeal history) but remain untreated. This gap, not the stable lanadelumab base, is where a new entrant should aim.

The competitive clock is running: donidalorsen, KalVista's oral plasma-kallikrein inhibitor, reported a 69% attack-rate reduction in ZENITH-1 versus berotralstat's 44% in APeX-2, with an FDA submission in 2024 and possible US approval by 2025. Any new pre-launch entrant now competes not just against the two approved agents but against a pipeline drug likely to reset the oral efficacy bar before launch. A distinct commercial niche, the ~1,000-1,500 US patients with FXII-HAE or other normal-C1-INH variants who may respond less well to standard kallikrein-targeted prophylaxis, remains structurally underserved by all three.

Payer posture is precedent-driven: prior-authorisation criteria (confirmed Type 1/2 diagnosis, ≥3 attacks/year or laryngeal history, specialist sign-off) are already established by lanadelumab and berotralstat, and a new entrant's PA will largely mirror them absent a distinct eligibility population. ICER's 2021 berotralstat assessment set a fair-value benchmark close to berotralstat's ~$95,000/year WAC — pricing near or below that level, rather than toward lanadelumab's ~$450,000/year, produces the stronger cost-effectiveness position. Pre-launch priorities: quantify the never-prophylaxed cohort at the 40-80 HAE Alliance member centres, build attack-frequency and laryngeal-history identification tools ahead of launch, and decide specialty-pharmacy and copay-assistance architecture before donidalorsen's approval compresses the window.

This assessment synthesises three independent research angles (competitive positioning, target-population epidemiology, and anticipated payer posture) into one integrated pre-launch view. Every figure is drawn from the named primary source in the underlying research base and cross-checked before inclusion; no figure is carried from model memory.

HAE launch-readiness sources: US HAE Association member survey 2023; BioCryst investor day 2023 and berotralstat launch market analysis 2021-2023; Takeda HAE market research; Maurer M et al., WAO HAE guidelines 2022; Cicardi M et al., Allergy 2012; Magerl M et al., Allergy 2019 (HAE variant types); KalVista donidalorsen NDA / ZENITH-1 ClinicalTrials.gov results 2024; ICER berotralstat HAE value assessment 2021; UHC medical policy HAE prophylaxis 2024; Cigna PA berotralstat 2024; Express Scripts HAE formulary.