Sanofi returns to Dren Bio for another B‑cell depletion therapy with $100M upfront

Sanofi has entered a new strategic collaboration with Dren Bio focused on developing a next‑generation B‑cell depletion therapy for autoimmune diseases.1 4

Coverage of the transaction reports that Sanofi is paying $100 million upfront to Dren Bio as part of this latest deal, with additional biobucks (milestone and royalty) potential bringing the total deal value up to about $1.7 billion.3

This new agreement follows Sanofi’s earlier acquisition of Dren Bio’s DR‑0201 program (now SAR448501), a bispecific myeloid cell engager for deep B‑cell depletion, announced in March 2025 with a $600 million upfront payment.2 5

DR‑0201/SAR448501 is a CD20‑directed bispecific antibody designed to engage tissue‑resident and trafficking myeloid cells to induce deep B‑cell depletion via targeted phagocytosis, and is being evaluated in two phase 1 studies.1 2

Dren Bio’s targeted myeloid engager and phagocytosis platform aims to achieve immune reset by inducing deep depletion of pathogenic B cells, potentially enabling sustained treatment‑free remission in B‑cell–mediated autoimmune diseases such as lupus.1 2

The expanded collaboration underscores Sanofi’s strategy to broaden its immunology pipeline and reinforce its ambition to become a leading company in immunology through strategic licensing and acquisitions.2 3

According to Dren Bio, the multispecific antibodies from its platform are engineered to activate phagocytic mechanisms only in the presence of disease targets, potentially offering a superior safety profile compared with other immunomodulatory therapies.1