Anti-HER3 Antibody (Patritumab)

Patritumab (BPS Bioscience #84316) is a component of the ADC(antibody drug conjugate) Patritumab Deruxtecan (BPS Bioscience #84315) and also functions as neutralizing monoclonal antibody targeting HER3 (human epidermal growth factor receptor 3). HER3 (human epidermal growth factor receptor 3) is a transmembrane protein encoded by the ERB3 gene. HER3 is broadly expressed in human tissues however, increased expression of HER3 has been linked to a variety of solid tumors including ovarian, breast, colon, and gastric cancers and correlates with decreased overall survival in colorectal cancer patients. HER3 has the unique property of being inherently catalytically inactive but still being able to participate in ligand binding, forming heterodimers with nearby receptors of the HER family. The formation of these dimers initiates a cascade of downstream signaling steps critical to cell proliferation. The binding and subsequent phosphorylation of HER3 by HER2 or EGFR (epidermal growth factor receptor) has been found to play a role in tumor growth and drug resistance. Due to its cell surface expression in a variety of cancers and correlation with decreased survival, HER3 is a prospective therapeutic target for antibody-drug conjugate (ADC) development. Patritumab deruxtecan is an ADC composed of the antibody Patritumab, and deruxtecan. Derutexcan contains the linker and the payload (topoisomerase I inhibitor). This ADC had received Breakthrough Therapy Designation by the FDA in 2021 for the treatment of advanced or metastic EGFR-mutated NSCLC (non small cell lung cancer). In 2025, after a phase 3 trial, it was removed as it did not meet the overall survival (OS) endpoint. Despite that, the development of an ADC targeting HER3 has opened new therapetic options for this target.