Johnson & Johnson has agreed to acquire Firefly Bio, a South San Francisco, California-based bio/pharmaceutical company specializing in degrader antibody conjugates (DACs), for $1 billion.  

The acquisition includes Firefly Bio’s Firelink proprietary platform for producing DACs, a new modality for cancer treatments, which combines properties of antibody drug conjugates (ADCs) with selective protein degraders to overcome limitations associated with each. Although traditional ADCs have favorable bioavailability and the ability to target cells, they often have a limited therapeutic index due to their broadly cytotoxic payloads and lack the ability to knock down specific intracellular proteins, according to information from FireFly Bio. With protein degraders, the converse applies: these therapies have intracellular selectivity, protein knock-down, and are highly catalytic but may have bioavailability issues and do not have the ability for cell-specific targeting. Firefly’s proprietary platform uses catalytic protein degraders as the payloads of ADCs, and the company has proprietary linker technology to join these modalities. Firefly Bio debuted as a company with a $94-million financing round in February 2024, which among other investors included Versant Ventures and Eli Lilly and Company.  

In announcing the acquisition, J&J noted the potential of the DAC platform for treating KRAS-driven tumors and other solid tumors. “KRAS has notoriously been considered an undruggable target and patients with KRAS-driven cancers continue to face limited treatment options with survival measured in months, not years,” said John Reed, M.D., Ph.D., Executive Vice President, Innovative Medicine, Research & Development, Johnson & Johnson, in a June 8, 2026, press statement. “We believe the proprietary Firelink platform will overcome the limitations of current treatments and diversify our pipeline with preclinical candidates for treating multiple types of solid tumors.” 

Under the agreement, Johnson & Johnson will acquire Firefly Bio for $1 billion in cash. The closing of the transaction is expected to occur later this year (2026), subject to applicable regulatory approvals and other customary closing conditions.  

Source: Johnson & Johnson