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Seagen makes targeted cancer drugs that deliver powerful medicine more precisely to tumors.
Seagen is a cancer drug company. It builds medicines that work like guided missiles: instead of flooding the whole body with poison, its drugs attach to markers found mostly on tumor cells and deliver the punch there. The core technology is called an antibody-drug conjugate, or ADC — an antibody that finds the cancer cell, a chemical payload that kills it, and a linker holding the two together. Getting that linker right is the hard part, and Seagen spent decades refining it.
The company sells several approved drugs, but the most important is a set of medicines built on that ADC platform. Its best-known products treat lymphomas and other blood cancers, plus bladder cancer and breast cancer. The customers are oncologists and hospitals, and the bills are mostly paid by insurers and government health programs. Seagen also makes money by licensing its technology to bigger partners — most notably Pfizer and Genmab — who help develop and sell the drugs. That partnership model matters because cancer drug trials are slow and expensive, and sharing the cost and reach is often smarter than going it alone. The catch is that Seagen has been a chronic money-loser on paper, plowing cash into research while racking up big losses, and the business is heavily dependent on a small number of drugs. Competition in the ADC space has exploded, with rivals like Roche and Astellas chasing the same idea. Then came the twist: Pfizer agreed in 2023 to buy Seagen for roughly $43 billion, one of the largest deals in biotech history. Pfizer wanted the ADC platform and the pipeline, since its own COVID-era cash pile needed a home and some of its older drugs were losing patent protection. That deal closed in December 2023, so Seagen is now a Pfizer subsidiary rather than an independent public company. The story is a useful lesson in how biotech works: years of losses and scientific grind can still end in a giant payday if the platform turns out to be valuable. The remaining question is whether Pfizer can turn the science into steady profits before rival ADCs and cheaper competition eat into the lead.
Saved answer · last researched 23 Oct 2026
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