Eli Lilly Acquires Rights to CSL's IL-6 Inhibitor in $100M Deal

Eli Lilly has paid $100 million for rights to a clinical-stage CSL Limited drug targeting chronic inflammation, expanding its pipeline in the competitive cardiometabolic space. The deal gives Lilly rights to clazakizumab, a monoclonal antibody designed to bind to and block IL-6, in indications beyond cardiovascular event prevention in end-stage kidney disease patients, where CSL retains rights.

Clazakizumab addresses an increasingly competitive target associated with chronic inflammation. While FDA-approved antibody drugs that block this target have already reached the market in certain inflammatory disorders, there's renewed industry interest in expanding this approach to more diseases, particularly the inflammation that drives cardiovascular conditions. The drug was initially developed by Vitaeris, which had partnered with CSL subsidiary CSL Behring on development for preventing organ transplant rejection before CSL Behring acquired Vitaeris in 2020.

Lilly, a longtime leader in diabetes drugs, expanded its scope to obesity with the blockbuster drug Zepbound. That product and type 2 diabetes medicine Mounjaro together accounted for more than half of Lilly's $65.1 billion in 2025 revenue, and the company said in its annual report that it expects cardiometabolic health products will continue to be a "significant and growing portion of our business, revenues, and prospects." The company's tirzepatide molecule, marketed as Mounjaro and Zepbound, emerged as one of the world's best-selling prescription medicines throughout 2025.

The cardiometabolic health portion of the Lilly pipeline includes the small interfering RNA drug lepodisiran and the oral small molecule muvalaplin, both in late-stage development for atherosclerotic cardiovascular disease. Lilly has been adding more prospects via business deals, including last year's $1 billion acquisition of Verve Therapeutics and last month's $1.4 billion agreement to acquire Ventyx Biosciences, which will bring VTX3232, a small molecule inhibitor of the NLRP3 inflammasome.

Beyond Lilly's $100 million upfront payment, CSL is eligible to receive milestone payments tied to the progress of clazakizumab. CSL could also receive royalties from Lilly's sales of clazakizumab if the pharma company is able to commercialize it. The company's late-stage development pipeline progressed substantially in 2025, with more than 25 Phase 3 trials delivering positive outcomes, and Eli Lilly initiated 12 additional Phase 3 programmes across its therapeutic focus areas, including potential treatments for cardiovascular disease and non-small cell lung cancer.