The mechanism: Orphan drug exclusivity (seven years) and biologic exclusivity (12 years) are legal cliffs, not patent thickets you can litigate around forever. When they expire, the FDA can approve a competing product on safety and efficacy alone — no patent fight required. Biogen learned this the hard way when a federal judge invalidated its core Tecfidera patents in 2020 and Mylan launched a generic mid-quarter, vaporizing roughly a third of that quarter's revenue overnight. That precedent matters now because Biogen's second-largest franchise, Tysabri, lost its patent shield when the FDA approved Sandoz's natalizumab biosimilar Tyruko in August 2023 — and Sandoz finally launched it commercially in the U.S. in November 2025. Vertex is running the opposite playbook: it got FDA approval for Alyftrek in December 2024, a next-generation CFTR modulator clinically superior enough to reset the exclusivity clock and pull patients off Trikafta before generics ever get the chance.
Who cashes in:
- VRTX — Alyftrek is a defensive masterstroke: it converts Trikafta's expiring exclusivity into a fresh, patent-protected franchise built on the same CF patient base, while Casgevy (with partner CRISPR Therapeutics) is projected to nearly triple 2026 revenue as sickle-cell and beta-thalassemia patient starts scale, and Journavx gives Vertex a genuine non-CF, non-orphan growth leg.
- NTLA — Intellia's lonvo-z, a one-time in vivo CRISPR treatment for hereditary angioedema, completed rolling BLA submission in 2026 with a targeted first-half-2027 launch; a first-in-category approval creates new orphan exclusivity from scratch rather than defending an old one, the model Vertex is proving works.
- REGN — Regeneron's biologics franchise (Eylea HD, Dupixent) shows how patent-cliff-tested companies reload with label expansions and reformulations rather than relying on a single exclusivity period.