The FDA on Monday approved Venclexta (venetoclax), a new oral blood cancer drug developed by Roche and AbbVie.

The drug, which had received Priority Review status in January, was also granted Breakthrough Therapy designation by the FDA in May of last year. The FDA cleared Venclexta through its accelerated approval pathway.

Venclexta is approved to treat a specific form of chronic lymphocytic leukemia: these patients have a genetic abnormality known as 17p gene deletion and have tried one prior therapy. The gene abnormality is believed to occur in approximately 10% of patients with untreated CLL and nearly 20% of patients with relapsed forms of the disease.

Cowen Group analysts have estimated that the drug could bring in sales of $2 billion by 2020, according to multiple news reports. The annual cost for the first year of Venclexta is roughly $109,500. Roche and AbbVie offer patient assistance programs for people taking the drug. . 

Venclexta could be part of AbbVie’s strategy to replace revenues for its flagship product, Humira, which is expected to soon face biosimilar competition. The drug loses patent protection in December. The FDA in January accepted Amgen’s application for a Humira biosimilar — dubbed ABP 501. AbbVie has said, however, that believes it has legal protection to keep Humira safe from competition until 2022.

Humira accounts for more 60% of the drugmakers’ total revenue and is the best-selling drug in the world. It brought in sales of $14 billion in 2015.  Merck, Novartis, Baxalta, and other drugmakers are all working on developing biosimilar versions of Humira.

The clinical trial supporting Venclexta’s approval showed that 80% of the 106 participants experienced a complete or partial remission of their cancer. The drug is taken orally.

Sandra Horning, Roche’s chief medical officer, said in a statement that “up to half of people whose CLL progressed have 17p deletion, a genetic marker that makes the disease difficult-to-treat…[Venclexta] represents a way to help people who have been previously treated and have this high-risk form of the disease.” This deletion becomes increasingly prevalent as the disease worsens.

Venclexta is the first BCL-2 inhibitor to be approved by the FDA. The drug targets the B-cell lymphoma 2 protein, which is believed to support cancer cell growth. Venetoclax is also being studied in combination with Imbruvica as a first-line treatment in chronic lymphocytic leukemia.

AbbVie in 2015 acquired Pharmacyclics, which developed Imbruvica and co-markets the drug with Johnson & Johnson.