In an effort to strengthen its portfolio of hepatitis C drugs, Merck will buy the biotechnology company Idenix Pharmaceuticals for $3.85 billion, the companies announced on Monday.

In the deal approved by both companies’ boards of directors, Merck will pay $24.50 in cash for each share of Idenix, 3.4 times its Friday’s closing price of $7.23 a share. The companies expect the deal to close in the third quarter of this year.

Cambridge, Mass.-based Idenix, whose primary focus is on the development of oral antiviral therapeutics to treat hepatitis C virus (HCV), has three HCV drug candidates in clinical development: two nucleotide prodrugs (IDX21437 and IDX21459) and a NS5A inhibitor (samatasvir). These new candidates are being evaluated for their potential inclusion in the development of all oral combination regimens.

Idenix dropped two earlier HCV drugs because of potential safety issue, the company said.

Merck’s has several HCV medicines in development, the leading of which is a combination of MK-5172, an investigational HCV NS3/4A protease inhibitor and MK-8742, an investigational HCV NS5A replication complex inhibitor. A combination of these two candidates has received Breakthrough Therapy designation from the FDA for the treatment of HCV, and Merck announced Phase 3 clinical trials of the combo were initiated in April.

“Idenix has established a promising portfolio of hepatitis C candidates,” said Roger Perlmutter, president of Merck Research Laboratories. These candidates would help Merck develop a pill that’s highly effective against all subtypes of the hepatitis C virus and taken once a day for as short a duration as possible, he added.

Merck is hoping to bring a combination of two of its hepatitis C drugs to market in the next year or two, the companies said. — Kellen Owings

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