Mallinckrodt plc / Questcor Pharmaceuticals, Inc.

Infantile Spasms (West Syndrome) and Multiple Acthar-indicated Inflammatory/Autoimmune Conditions

2K US cases/yr · $761M Acthar 2013 net sales (Questcor)

Disease Overview

H.P. Acthar Gel is a repository corticotropin (porcine ACTH analog) injection with a basket of legacy on-label indications — most clinically critical of which is infantile spasms (West syndrome), a rare catastrophic infantile epilepsy with ~2,000-2,500 new US cases annually where prompt cessation of spasms predicts long-term neurodevelopmental outcome. Other on-label uses include MS relapse, nephrotic syndrome, lupus, RA, dermatomyositis/polymyositis, sarcoidosis, and ophthalmic disorders, though the clinical evidence base supporting Acthar versus standard-of-care steroids in many of these adult indications has been a long-standing point of payer and analyst debate.

Competitive Landscape

Acthar's commercial moat at deal time was 'one molecule, many indications' grandfathered orphan/specialty pricing rather than head-to-head differentiation. In infantile spasms, Acthar competed with vigabatrin (Sabril, Lundbeck) — the other FDA-approved first-line option — plus off-label oral prednisolone protocols increasingly used internationally as a lower-cost alternative. In MS exacerbations, the competing standards are high-dose IV/oral methylprednisolone (generic, pennies on the dollar relative to Acthar) and plasma exchange for steroid-refractory cases, making Acthar's ~$30K-$40K-per-vial price point a payer flashpoint. In nephrotic syndrome and lupus, generic corticosteroids and modern immunosuppressants (rituximab, mycophenolate, cyclophosphamide, calcineurin inhibitors) dominate. Mallinckrodt's $5.6B (closed at ~$5.8B) bet was that Acthar's $761M 2013 net sales (+49.6% YoY) could continue compounding via medical-affairs investment and indication expansion. FiercePharma at announcement headlined the deal as 'a $5.6B bet on Questcor and its controversial Acthar drug,' explicitly flagging legacy pricing scrutiny risk. That risk became the defining post-deal story: a $100M FTC settlement over anticompetitive blocking of a synthetic ACTH competitor (Synacthen Depot), House Oversight Committee investigation, Medicare exposure (CMS spend exceeded $2B over the period), whistleblower kickback litigation, and ultimately Mallinckrodt's bankruptcy filings — culminating in the 2026 combination with Endo and rebrand to Keenova.