The transaction will involve Sanofi acquiring all outstanding shares of Synthorx for $68 per share, equating to a total transaction figure of $2.5bn (€2.26bn).
The deal will see Sanofi acquire Synthorx’s pipeline of ‘optimized biologics’, which are created by adding a new DNA base pair that, in turn, allows for the incorporation of novel amino acids into unique proteins.
Using its platform, Synthorx states that it can create ‘enhanced’ therapeutic proteins that do not possess the limitations of natural amino acids.
The biotech’s lead candidate is THOR-707, which is a variant of recombinant human IL-2 that has been designed to kill tumor cells by increasing CD8+T and NK cells.
According to Synthorx, uptake of existing IL-2 therapies has been limited due to toxicity, such as vascular leak syndrome.
THOR-707 is currently in Phase I studies as a monotherapy and the biotech suggests that it has ‘improved selectivity’ and ‘reduced risk of anti-drug antibodies’ over current IL-2 therapies, potentially lowering risk of toxicity.
The drug candidate is also being studied alongside immune checkpoint inhibitors, specifically with a PD-1 inhibitor that is approaching human studies.
Explaining the decision to acquire the biotech, Sanofi pointed to the potential for combination therapies, as well as treatments outside of oncology as a reason for making the acquisition.
John Reed, global head of R&D at Sanofi, said, “By selectively expanding the numbers of effector T-cells and natural killer cells in the body, THOR-707 can be combined with our current oncology medicines and our emerging pipeline of immuno-modulatory agents for treating cancer.”
He continued, “Synthorx’s pipeline of engineered lymphokines has great promise not only for oncology but also for addressing many autoimmune and inflammatory diseases.”
Beyond THOR-707, the biotech also has two pre-clinical candidates within immuno-oncology and a further candidate focused on autoimmune disease.
The acquisition is the largest deal the French drugmaker has made in the last two years, when it outbid Novo Nordisk to add Ablynx to its portfolio for $4.8bn.