Merck (NYSE:MRK) marked a major milestone in its bid to introduce a new formulation for its famous cancer therapy pembrolizumab on Tuesday as its blockbuster intravenous version, marketed as Keytruda and generated $25B in sales in 2023 is set to face significant regulatory hurdles.

Merck said on Tuesday a study showed its injectable version of cancer drug Keytruda was not inferior to the currently approved intravenous formulation of its treatment, likely making it even more accessible and easier to administer.

Merck plans to discuss the data with regulators as it lags rivals Roche and Bristol Myers in bringing forward a subcutaneous form of its cancer drug.