Sanofi Chief Executive Paul Hudson said in a statement that the deal "is aligned with our goal to build our oncology franchise with potentially practice-changing medicines and novel combinations.”
At last check on Monday, Synthorx’s stock had nearly tripled to $67.40 from Friday's close just above $25.
The products at Synthorx, based in La Jolla, Calif., are designed to boost the ability of the body's immune system to fight tumors, the Wall Street Journal reported.
The transaction, subject to conditions including antitrust clearance, is expected to close in the first quarter. Sanofi said it would finance the deal with cash on hand.
Reuters reported that Sanofi was contemplating a joint venture or an outright sale for its consumer healthcare unit as part of a broad strategy review under Hudson, who took over as CEO on Sept. 1. The company's Investor Day is tomorrow.
Sanofi previously had been active in the M&A market, securing the $11.6 billion purchase of American hemophilia-drug maker Bioverative in 2018.
Separately, Sanofi said that its Sanofi Pasteur global vaccines unit entered a $226 million pact with the U.S. Department of Health and Human Services to increase the company’s domestic pandemic influenza vaccine production capabilities at its Swiftwater, Pa., plant.
Sanofi's public and private partnerships are key to its efforts to help protect people from influenza, said David Loew, executive vice president of vaccines at Sanofi.