GSK to buy liver drug efimosfermin for up to $2bn

GSK recently announced its acquisition of Boston Pharmaceuticals' promising liver disease candidate, efimosfermin alfa, which is set to enter phase 3 development. The deal is valued at up to $2 billion and marks a significant step in addressing unmet medical needs in the field of liver disease. Efimosfermin alfa is an experimental drug aimed at treating and preventing the progression of steatotic liver disease (SLD), a condition characterized by the accumulation of fat in the liver, often leading to inflammation and fibrosis.

SLD encompasses conditions such as metabolic dysfunction-associated steatohepatitis (MASH) and alcohol-related liver disease (ALD), affecting about 5% of the global population. GSK highlights the urgent need for effective treatments in this area due to the significant health challenges posed by these conditions.

Efimosfermin is administered monthly through a subcutaneous injection and functions as a fibroblast growth factor 21 (FGF21) analog. In a phase 2 trial, it demonstrated the ability to rapidly and significantly reverse liver fibrosis, halting its progression in patients with moderate to advanced MASH. This drug will also undergo evaluation for its efficacy in ALD. Its direct anti-fibrotic action could make it suitable for addressing more advanced stages of SLD and potentially using it in combination with GSK's siRNA therapeutic GSK'990, which is currently undergoing development for different subsets of SLD patients.

Tony Wood, the chief scientific officer at GSK, expressed optimism about efimosfermin's potential to redefine standard care, citing its convenient monthly dosing and favorable tolerability. He noted that efimosfermin is expected to significantly bolster GSK's hepatology pipeline and presented a promising opportunity to develop a new best-in-class medicine, with the first launch anticipated in 2029. This advancement complements GSK'990, which is also being developed for ALD and MASH, providing GSK with the flexibility to explore both monotherapy and combination therapy options to enhance patient outcomes.

To acquire efimosfermin, GSK will purchase Boston’s subsidiary BP Asset IX for an initial sum of $1.2 billion, with additional success-based milestone payments potentially bringing the total to $800 million. Furthermore, GSK will handle success-based milestone payments and tiered royalties payable to Novartis Pharma for efimosfermin.

Elias Zerhouni, the chairman of Boston’s board, expressed his satisfaction with the agreement, emphasizing GSK's recognition of efimosfermin's potential in addressing a significant global public health issue and unmet medical need. He looked forward to the continued development of efimosfermin as a leading treatment for patients suffering from SLD.

This strategic acquisition enhances GSK’s position in the hepatology domain and underscores the company's commitment to developing innovative therapies for liver diseases. With efimosfermin alfa, GSK is poised to make substantial strides in delivering effective treatments for SLD, ultimately aiming to improve the quality of life for millions of patients worldwide.