Express Scripts Formulary Addition Marks Progress in Milestone's Critical Payer Coverage Drive

What happened

Milestone Pharmaceuticals is navigating the high-stakes early launch of CARDAMYST, its FDA-approved nasal spray for PSVT, with recent operational steps including U.S. retail availability in late January 2026 and a sales force deployment in mid-February. The company announced that Express Scripts, one of the largest pharmacy benefit managers, has added CARDAMYST to its commercial national formularies effective March 27, 2026, a move aimed at improving patient access. This development directly targets a core risk identified in the DeepValue report: payer coverage is essential to mitigate abandonment at the high wholesale acquisition cost of ~$1,649 and support repeat utilization beyond initial copay-bridge programs. However, the announcement lacks critical specifics such as formulary tier placement, prior authorization details, or the percentage of covered lives, which are necessary to quantify its impact on adoption and net pricing. Without these metrics, it remains unclear whether this win will achieve the >50% covered lives threshold by 2Q26 that could elevate the investment thesis, leaving the commercial story still reliant on forthcoming key performance indicators.

Implication

In the immediate term, this formulary addition lowers the barrier to prescriptions by easing reimbursement concerns, potentially boosting early fills as physicians gain confidence in access, though it may still rely on copay support if terms are restrictive. It aligns with the bull scenario in the DeepValue report, where rapid payer coverage accelerates net sales and reduces financing risk by improving effective affordability beyond the $25 copay-bridge period. However, the bear scenario persists if other major PBMs delay coverage or if Express Scripts imposes high out-of-pocket costs, keeping abandonment elevated and net revenue immaterial through 2026. Investors should closely monitor Milestone's upcoming quarterly disclosures for launch KPIs—such as total prescriptions, unique prescribers, and covered lives percentages—to assess whether this win translates into measurable traction or remains a promotional headline. Long-term, success hinges on converting this initial access into durable payer relationships and patient adherence, which will determine cash-flow inflection by late 2027 and mitigate dilution risk from the encumbered capital structure.

Thesis delta

This news incrementally shifts the thesis towards reduced downside risk by addressing payer coverage, a key condition for upside in the DeepValue report, but it does not constitute a fundamental upgrade until quantified metrics confirm covered lives exceed 50% by 2Q26. If subsequent data shows this formulary win drives reported script growth and expands access, it could increase conviction in the base or bull scenarios; otherwise, the thesis remains anchored to 'show-me' dynamics with unproven demand.