The terms, per the grant. On April 12, 2022, Daiichi Sankyo was issued US11298359B2, covering an anti-HER3 antibody-drug conjugate. The CPC stack is heavy on the conjugation series — A61K 47/6803/6851/6855/6857/6861/6863/6869 — alongside the anti-HER3 antibody claims (C07K 16/2863 and related), showing the linker-payload architecture as the protected core.

Why a teardown separates the payload layer: in ADCs, the same linker-payload technology can be deployed against many different antibody targets. That makes the conjugation IP a reusable platform asset, whereas the antibody claims are target-specific. The durable, compounding royalty value often lives in the payload-and-linker layer because it touches every program built on the platform.

“To provide an antitumor drug having excellent therapeutic effect, which is excellent in terms of antitumor effect and safety.”— U.S. Patent No. 11,298,359 source

The structure point: a conjugate deal can be priced as a target-specific license (the antibody) plus a platform license (the linker-payload). For a model, the platform component is the higher-multiple asset because its royalty base grows with each new target the technology is applied to.

What the grant does not promise: a clinical outcome, an approval, or exclusivity over all conjugation chemistries. It is an exclusivity claim on a specific anti-HER3 conjugate, sitting within a field where multiple payload-and-linker platforms compete.

The takeaway: in any ADC term teardown, value the linker-payload IP separately from the antibody, because that is where reusable, compounding royalties sit. Daiichi Sankyo's April 2022 HER3-ADC grant is a dated example of the conjugation-centered architecture.