Seagen plots new biologics plant to amp up antibody drug production

With a potential market expansion on the horizon, antibody-drug conjugate specialist Seagen has laid out a plan to bolster its manufacturing capacities.

Seagen will build a 270,000-square-foot biologics facility in Everett, Washington, north of the company’s U.S. headquarters in the nearby city of Bothell, where the company already runs a biologics plant.

After the new facility comes online in 2024, Seagen plans to eventually house up to 200 workers at the site to supply drugs for clinical trials and commercial use. It will include monoclonal antibody production, fill & finish, quality control labs, package & labeling, warehouse and office space, a Seagen spokesperson told Fierce Pharma.

Construction is already underway and will happen in phases, the spokesperson said. The company is still finalizing the final budget but estimates that the investment will be in the low hundred-millions in the initial phase.

Seagen currently relies heavily on partners and contract manufacturers to make its cancer medicines, but the drugmaker figures the new Everett facility could give it “greater control and flexibility” over production.

“In cancer research and development, Seagen must continue to be agile and flexible, especially in manufacturing, to advance our promising pipeline of medicines for people living with cancer and bring these medicines to patients as fast as possible,” Seagen CEO Clay Siegall, Ph.D., said in a statement.

The new site plan comes as Seagen anticipates a critical readout for its Astellas-partnered drug Padcev in combination with Merck & Co.’s Keytruda. The closely watched cohort K of the EV-103 trial is testing the combo in newly diagnosed bladder cancer patients who are not eligible for cisplatin-based chemotherapy. The company expects data from the study in the second half of this year. If it's positive, the data could deliver an accelerated FDA approval and open up a large front-line market for the drug.

With an approval in previously treated bladder cancer, Padcev is Seagen’s second-largest bread earner with 2021 sales of $222 million attributed to the company. Wall Street consensus currently has Padcev doubling its sales to reach $458 million in 2022, Berenberg analyst Zhiqiang Shu, Ph.D., said in a Monday note.

Per their agreement, Astellas is in charge of manufacturing the anti-Nectin-4 drug. But if the two companies determine an additional source is needed, Seagen is responsible for establishing that supply, whether internally or through a third party.

As for Seagen’s best-seller—but not so much of a growth driver—the blood cancer drug Adcetris is manufactured by several contractors, including AbbVie and Merck KGaA.

Seagen recently took on additional manufacturing tasks with an FDA approval for its Genmab-partnered drug Tivdak in previously treated cervical cancer. But for the foreseeable future, Seagen expects contractors to supply that drug, according to its 2021 annual report.

Beyond those commercial products, Seagen has a growing pipeline of ADCs. These include disitamab vedotin, a HER2-targeted ADC that Seagen licensed from China’s RemeGen last year in a deal potentially worth $2.6 billion. And then there's a LIV-1 ADC, which is featured in a $1.6 billion partnership with Merck & Co. for breast cancer and other solid tumors.

Editor's Note: The story has been updated with additional information on the new plant from Seagen.