When a commercial-stage specialty pharma company pursues a second approved indication accessible via the same specialist audience and existing rep infrastructure, the incremental unit economics are dramatically superior to the first indication. Sales force is already deployed and paid. REMS infrastructure (if any) already built. KOL relationships already cultivated. Managed care contracting already in place. The additional indication functions like software adding a product line to existing customers: gross margin on incremental revenue approaches 100%, while SG&A per incremental dollar of revenue approaches zero. This is fundamentally different from a new product launch, which requires full SG&A re-loading. Model second-indication revenue as ultra-high-margin optionality, not as a proportional SG&A drag.
When valuing specialty pharma pipeline catalysts, distinguish between: (a) new product requiring full commercial infrastructure build (model full SG&A loading), (b) formulation change on existing drug (partial SG&A, distribution re-work), and (c) additional indication for an already-commercial drug serving the same specialist channel (near-zero incremental SG&A, pure gross margin revenue). Category (c) is systematically undervalued by the market because investors apply the same launch cost assumptions as the original launch. In rare disease pharma specifically, the same KOL network and specialist rep force often spans multiple indications within the same organ system — making category (c) common. Screen for companies with a commercial rare disease asset + a pipeline candidate in the same organ system.