Pfizer has completed its $43-billion acquisition of Seagen (formerly Seattle Genetics), a Bothell, Washington-based bio/pharmaceutical company specializing in antibody-drug conjugates (ADCs) and drugs for oncology. The acquisition was announced in March 2023. 

Seagen’s portfolio includes four approved medicines that are indicated across solid tumors and hematologic malignancies, including three ADCs: Adcetris (brentuximab vedotin), Padcev (enfortumab vedotin), and Tivdak (tisotumab vedotin). The company also commercializes Tukysa (tucatinib), which was approved earlier this year (January 2023) for treating certain types of colorectal cancer in combination with trastuzumab. Clinical development programs are ongoing for each of these medicines for potential new tumor types or expanded indications in earlier lines of therapy, with catalysts expected annually through 2027.  

With the addition of Seagen, Pfizer’s oncology pipeline has doubled in size with 60 programs spanning multiple modalities, including ADCs, small molecules, bispecifics, and other immunotherapies. Pfizer’s oncology portfolio now includes over 25 approved medicines and biosimilars across more than 40 indications, including nine medicines that are either blockbuster (defined as sales of $1 billion or move) or have the potential to be blockbuster. 

To address US Federal Trade Commission concerns, which provided the US regulatory approval for the acquisition, Pfizer has chosen to irrevocably donate the rights of royalties from US sales of the immunotherapy drug, Bavencio (avelumab), indicated for treating Merkel cell carcinoma (a form of skin cancer), urothelial carcinoma, and other tumor types, to the American Association for Cancer Research.  

Source: Pfizer