Having recently disclosed that Merck & Co. is the company using its hyaluronidase-derived technology, Alteogen has now revealed that the US drugmaker has exclusive access for use alongside its anti-PD-1 therapy Keytruda (pembrolizumab). The change in the licensing deal comes with a $20-million upfront payment to Alteogen and potential milestones of up to $432 million.Alteogen first announced in 2020 that it had partnered with an unnamed drugmaker on use of its recombinant human hyaluronidase enzyme ALT-B4 across a number of products. The technology allows large-volume subcutaneous administration of biologics that would otherwise be administered as an intravenous injection.At the time, Alteogen said it received an initial payment of $16 million and was eligible for milestones totalling up to nearly $3.9 billion for the products covered under the agreement. Park Soon-jae, chief executive of Alteogen, noted that the identity of its previously unnamed partner has now been made public as “there was no reason” not to disclose it, also hinting at successful progress in Phase III trials for the subcutaneous version of Keytruda.Convenience and biosimilar protectionMerck, along with other makers of PD-(L)1 inhibitors, including AstraZeneca, Bristol Myers Squibb and Roche, have been hastily working on subcutaneous formulations of their products, not only to improve patient convenience, but also to protect against patent expiry on the intravenous versions.Roche’s subcutaneous version of Tecentriq (atezolizumab) is already approved in the EU and UK, while Bristol Myers Squibb has reported positive Phase III data for its subcutaneous formulation of Opdivo (nivolumab). Both products use Halozyme's Enhanze drug delivery technology.However, Merck has fallen behind in its development efforts, with a first-generation version of subcutaneous Keytruda looking to have been deprioritised. The company has previously indicated that Phase III data for the subcutaneous version of Keytruda using ALT-B4 are due to read-out later in 2024, with the price of the product likely taking into account the availability of cheaper biosimilar intravenous versions. For related analysis, read Spotlight On: Analyst sceptical on Big Pharma’s subcutaneous PD-(L)1 strategy.