Pieris Pharmaceuticals, Inc. / Seattle Genetics, Inc.

Solid Tumors and Hematologic Malignancies (Bispecific Immuno-Oncology)

Disease Overview

Bispecific Antibody-Anticalin fusion proteins combine a tumor-targeting monoclonal antibody (e.g., anti-HER2) with a costimulatory Anticalin (e.g., 4-1BB agonist) to focus T-cell activation in the tumor microenvironment, aiming to avoid the systemic toxicity that plagued first-generation 4-1BB agonists like urelumab. The platform addresses tumor-localized immune activation across HER2+ and other antigen-expressing solid tumors plus hematologic malignancies.

Competitive Landscape

The February 2018 collaboration was Pieris' third major Anticalin IO partnership after Servier (€1.7B, 2017) and Roche ($409M, 2015), positioning the platform as a dominant discovery franchise in tumor-localized costimulation. Seattle Genetics paid $30M upfront with up to $1.2B in success milestones across three bispecific programs plus tiered royalties to low double-digits. The collaboration was amended in March 2021: Pieris exchanged its 50/50 co-develop/co-commercialize option on program 2 for a US co-promotion right plus higher royalties, and Seagen made a $13M equity investment. Pieris' lead unpartnered asset, cinrebafusp alfa (PRS-343, 4-1BB x HER2), competed against Pfizer/Genmab's PF-07209960 and Alligator's ATOR-1017 in the costimulatory bispecific class. PRS-343 development was halted by Pieris in 2022 amid a 70% workforce reduction, and Pieris pivoted to its inhaled respiratory franchise with AstraZeneca. The Seagen programs were absorbed into Pfizer's pipeline following the $43B Seagen acquisition closed December 2023.