Exhibit 99.5
Message from John Reed—Sanofi to acquire Synthorx
December 9th, 2019
Dear Colleagues,
Today we announced Sanofi’s plans to acquire Synthorx, a clinical-stage biotechnology company focused on prolonging and improving the lives of people with cancer and autoimmune disorders. Both the company’s pipeline and their platform technology are attractive to us. See the press releasehere.
Synthorx is a clinical-stage biotechnology company focused on prolonging and improving the lives of people with cancer and autoimmune disorders. Synthorx’s proprietary,first-of-its-kind Expanded Genetic Alphabet platform technology expands the genetic code by adding a new DNA base pair and is designed to create optimized biologics, referred to as Synthorins. A Synthorin in a protein optimized through incorporation of novel amino acids encoded by the new DNA base pair that enables site-specific modifications, which enhance the pharmacological properties of these therapeutics.
The genetic codon extension technology is currently operationalized for bacterial production of recombinant proteins, though we have long-term aspirations to adapt the technology also for mammalian cell bioproduction. Synthorx currently relies on external contract manufacturing organizations (CMOs) for GMP protein production. We therefore anticipate eventually moving CMC and manufacturing to our Frankfurt site, which is well established for microbial fermentation bioproduction methods. Also, because Nanobodies® are readily produced in microorganisms, we envision a plethora for opportunities to marry Synthorx’s technology with our Nanobody platform at the Ghent site. Accordingly, we are eager to pursue several site-specific conjugations of small molecules, peptides, and proteins using “Click” chemistry-like methodologies.
With respect to the Synthorx pipeline, the company’s lead immuno-oncology (IO) product candidate,THOR-707, is a variant ofinterleukin-2(IL-2) that is undergoing clinical testing in multiple solid tumor types as a single agent and in combination with immune checkpoint inhibitors(anti-PD-1). It has the potential to become thebest-in-classIL-2 therapeutic for the treatment of a wide variety of malignancies. In early development,THOR-707 showed prolonged pharmacology with a three week dosing schedule, was devoid of anti-drug antibody (ADA) reactions, displayed a well-tolerated safety profile, and produced striking expansion of tumor-fighting effectorT-cells (CD8+) and Natural Killer (NK) cells in advanced cancer patients without causing elevations in immunosuppressive regulatoryT-cells (CD4+) or eosinophils. We envision broad utility forTHOR-707 as a combination partner for multiple molecules in Sanofi’s oncology pipeline, including cemiplimab (Libtayo), isatuximab (Sarclisa), and essentially all of our IO molecules that are earlier in their development journeys.
The Synthorx pipeline also contains preclinical assets that could be ready for development in approximately one to two years, including engineered versions ofIL-10 andIL-15 for oncology as well as a version ofIL-2 engineered for autoimmune diseases that selectively expands immunosuppressive Treg cells in preclinical species.
We anticipate that Synthorx’s novel and powerful discovery platform will have significant synergies with our drug discovery platforms at Sanofi, enabling the discovery of transformative medicines for oncology, immunology, and eventually other indications.
Today marks the first step in this process. Until the deal is completed (which we expect to occur in the first quarter of 2020, subject to conditions, such as antitrust clearance and other customary requirements), Synthorx will continue to operate as a separate company.
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