Will BRINSUPRI repeat prescriber rate exceed 60% by mid-2026?

Oral chronic disease therapies in unmet-need categories typically achieve 65-80% repeat prescriber rates after 12 months. BRINSUPRI's monopoly status and chronic disease indication strongly favor high repeat rates. However, the resolution requires both achieving 60% AND disclosure by Insmed — the disclosure risk is non-trivial as companies sometimes reframe or omit unfavorable metrics. The 50% single-Rx rate at this early stage is not necessarily alarming given the launch was only 6 months ago.

The conditional nature of this market — requires both achieving the rate AND disclosure — significantly reduces probability. Insmed has no obligation to report this metric in exactly the form the resolution requires. If the repeat rate is 58%, management might describe it as 'strong engagement' without giving a precise number, resulting in a NO resolution. This disclosure conditionality discounts what would otherwise be a 60-65% underlying probability.

Insmed has historically been transparent about prescriber metrics on earnings calls, which increases the disclosure probability. The company has incentive to share positive metrics (and the strong revenue suggests the repeat rate is healthy). If underlying repeat rate reaches 60%+ by mid-2026 (likely given chronic disease dynamics), disclosure probability is perhaps 70%. Combined: 0.70 × 0.75 underlying = ~0.52.

The 60% threshold may be aggressive for mid-2026 given the drug was only approved in August 2025. Many single-Rx prescribers may have started patients in Q4 2025 who haven't yet had time for a second prescription cycle (typical refill interval is 30-90 days). By mid-2026, the earliest prescribers will have 10 months of refill data but later adopters may still be in their first cycle. The metric timing creates meaningful uncertainty.

The disclosure risk is the dominant uncertainty. Companies rarely report granular prescriber metrics that could be unfavorable. If the repeat rate is 55% — healthy for this stage but below the 60% threshold — Insmed would likely frame it positively without providing the specific number. Resolution requires explicit disclosure, which is a meaningful filter.

Balancing the strong underlying fundamentals (chronic disease, no alternatives, oral formulation) against the disclosure conditionality yields approximately 50%. The underlying repeat rate is more likely above 60% than below by mid-2026, but the disclosure probability introduces sufficient uncertainty to pull the combined probability near coin-flip.

Chronic disease oral therapy with no alternatives should achieve strong repeat rates. The 60% threshold is achievable but the disclosure requirement adds meaningful uncertainty. Slightly above coin-flip.

The combination of a demanding threshold (60%), early-stage prescriber base (many still in first cycle), and disclosure risk pushes below 50%. More likely to see repeat rate in 50-60% range by mid-2026 with ambiguous disclosure.

A balanced assessment reflecting the tension between favorable chronic disease dynamics and the dual conditionality of achieving 60% AND having it disclosed. Net probability at coin-flip.