Pfizer’s $43B Seagen Buy Starts to Pay Off with Adcetris Phase III Data in DLBCL

Pfizer's oncology business

Pictured: Exterior view of Pfizer's office in Belgium/iStock, Alexandros Michailidis

Pfizer on Tuesday released results for the Phase III ECHELON-3 study, demonstrating that the antibody-drug conjugate Adcetris (brentuximab vedotin) significantly boosted survival in patients with relapsed/refractory diffuse large B-cell lymphoma when used with lenalidomide and rituximab.

The pharma did not provide specific data in its announcement, disclosing only that the Adcetris-based regimen led to a “statistically significant and clinically meaningful” improvement in overall survival versus lenalidomide and rituximab plus placebo.

The Adcetris combo also led to “positive outcomes” in various key secondary endpoints, including overall response rate and progression-free survival.

In terms of safety, Adcetris’ tolerability and adverse event profile was consistent with what had previously been established for the antibody-drug conjugate (ADC) in relapsed/refractory diffuse large B-cell lymphoma (DLBCL).

Roger Dansey, chief development officer of oncology at Pfizer, in a statement said that these data from ECHELON-3 indicate that Adcetris “could address an area of high unmet need in patients with relapsed or refractory DLBCL irrespective of CD30 expression.”

“These results are particularly encouraging because the study evaluated heavily pre-treated patients, including some who received prior CAR-T therapy,” Dansey added.

Originally developed by Seagen in collaboration with Takeda, Adcetris is an ADC that targets the CD30 surface protein, which is commonly expressed by certain blood cancers but not healthy cells. According to Seagen’s website, Adcetris carries a toxic payload called monomethyl auristatin E, which it releases inside the malignant cells triggering cell death.

Pfizer secured access to Adcetris in March 2023, when it bought Seagen for $43 billion.

Adcetris was first approved in August 2011 for the treatment of Hodgkin lymphoma and the rare systemic anaplastic large cell lymphoma. The ADC has since picked up several other approvals, allowing its use in other treatment settings and patient populations for these cancers.

The pharma partners are continuing to develop Adcetris in other subtypes and stages of Hodgkin lymphoma, peripheral T-cell lymphoma, non-small cell lung cancer and melanoma.

Tuesday’s readout will help Pfizer further deepen its expertise in ADC technology and expand its footprint in the space. Earlier this month, the pharma laid out its plans for its oncology franchise in the coming years. Key to its new strategy is a refined focus on four cancer types, which include hematologic malignancies such as lymphomas and multiple myeloma.

Pfizer is also looking to build up its biologics business, which it expects to comprise approximately 65% of its cancer franchise by 2030, up from its current 6% mix. The Seagen acquisition, with its deep ADC portfolio, will contribute heavily to potentially meeting this target.

Beyond Seagen, Pfizer in December 2023 also inked a potential $1.05 billion contract with Nona Biosciences to develop the Massachusetts-based biotech’s early-stage mesothelin-targeting ADC HBM9033 in solid tumors.

Tristan Manalac is an independent science writer based in Metro Manila, Philippines. Reach out to him on LinkedIn or email him at or

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