Fc receptor-like protein 5 (FcRH5) (FcRL5)

Fc receptor-like protein 5 (FcRH5), also known as FcRL5 or CD307, is a type I transmembrane glycoprotein and a member of the immunoglobulin superfamily primarily expressed on B-lineage cells [1]. It is characterized by the presence of eight extracellular immunoglobulin-like domains and a cytoplasmic tail containing immunoreceptor tyrosine-based inhibitory motifs (ITIMs) and an immunoreceptor tyrosine-based activation-like motif (ITAM), suggesting a dual role in regulating B-cell signaling [1, 3]. In the context of oncology, FcRH5 is highly and specifically expressed on the surface of malignant plasma cells in multiple myeloma, while its expression in healthy tissues is restricted to the B-cell lineage [2]. This restricted expression pattern makes it a promising therapeutic target for treating plasma cell dyscrasias [4]. Current therapeutic approaches include bispecific antibodies, such as cevostamab, which simultaneously bind FcRH5 on tumor cells and CD3 on T-cells to trigger T-cell-mediated lysis of the myeloma cells [2, 4]. Additionally, antibody-drug conjugates (ADCs) have been explored to deliver cytotoxic payloads directly to FcRH5-positive cells [5].

Other names

FcRH5CD307Fc receptor homolog 5IRTA2BXMAS1

T-cell redirection and activation via bispecific antibody binding (FcRH5 x CD3) and targeted delivery of cytotoxic agents via antibody-drug conjugates [2, 5]