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Synthetic biology company that created novel DNA base pairs and uses them to incorporate novel amino acids into proteins for potential therapeutics in areas of cancer and autoimmune disorders.

Formerly known as Alinos, Synthorx changed its name in 2014. The company created novel DNA base pairs d5SICSTP and dNaMTP (abbreviated X–Y) which can be replicated, maintained, transcribed and translated in vivo. Synthorx has a proprietary bacterial strain based on the E. coli manufacturing strain which expresses a nucleotide transporter that allows controllable maintenance of X-Y genetic information. Synthorin proteins are produced by the cell’s natural translation machinery using supplied and engineered components so that the X-Y codons are decoded by introducing novel amino acids.

The addition of X and Y to the genetic alphabet allows increased storage of information and the ability to incorporate novel amino acids into proteins. Synthorx is using its technology to address limitations of working with the twenty natural amino acids in protein therapeutics. For example, proteins can have dual and opposing functions due to interactions with different receptors. Synthorx can use the novel expanded genetic alphabet to create proteins capable of re-programming receptor interactions to potentially treat disease.


THOR-707 was designed to have advantages of current IL-2 therapies. THOR-707 is a variant of recombinant human IL-2 that is pegylated at one site so that it blocks engagement of the high affinity IL-2 receptor alpha chain. This extends the half-life of the drug and increases tumor distribution and retention. THOR-707 is designed to kill tumor cells by increasing CD8+ and NK cells while avoiding vascular leak syndrome.

Phase 1 and 2 clinical trials are testing THOR-707 as a single agent and in combination with Checkpoint Inhibitors.

IL-2 autoimmune (AI) Synthorin

IL-2 autoimmune (AI) Synthorin is developed for autoimmune disorders. IL-2 can dampen immune-cell activation but the short half-life of low dose IL-2 is impractical to administer for treatment of chronic autoimmune disorders. IL-2 AI Synthorin is being developed to overcome this limitation to treat chronic graft versus host disease (GVHD), atopic dermatitis and Crohn’s disease.


April 30, 2018
Synthorx raises a $63,000,000 series C round.
July 20, 2016
Synthorx raises a $10,000,000 series B round from RA Capital Management.
Synthorx was founded by Floyd Romesberg.

Funding Rounds


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