Pfizer's first new ADC from the Seagen pipeline just missed its Phase 3 in lung cancer. Cue the takes that the $43B deal is unraveling.

The scorecard tells a more useful story.

I mapped the 13 antibody-drug conjugates Pfizer acquired with Seagen and sorted them by what they were on deal day: four already on the market, nine in the pipeline.

The four marketed ADCs all deliver. Padcev keeps expanding in bladder cancer, Adcetris added a DLBCL approval, Tivdak holds cervical cancer, and disitamab is approved in China. The nine-asset inherited pipeline, the part Pfizer paid a premium for, has produced zero new approvals. Its record: one Phase 3 miss, four programs discontinued, four unproven, and over a billion dollars in write-offs. It still looks validated only because that value was on the market at close. Zoom out across 72 ADC deals since 2019 and the pattern repeats. Deal size never predicted the winners. AstraZeneca's cheaper bets on Daiichi's Enhertu and Dato-DXd are the cleanest wins of the era.

This is not ADCs failing. Sigvotatug is one of just five misses in 34 ADC Phase 3 readouts since 2024, a 74% hit rate.

The takeaway for ADC dealmaking: price the maturity of what you buy, not the size of the check.