(Reuters) –Britain’s GlaxoSmithKline (NYSE) agreed to purchase California-based biopharmaceutical firm Sierra Oncology, (NASDAQ:), in a cash transaction valued at $1.9billion, according to the companies. This deal is part of its efforts to expand its business with blood cancer.

Sierra’s shareholders, which is focused on targeted therapies to treat rare forms of cancer, will be paid $55 for each share of the common stock.

This is 39% more than Tuesday’s closing value and approximately two-thirds higher than the volume weighted average price, (VWAP), over the previous 30 trading day.

Sierra is preparing to submit in the second quarter U.S. marketing authorization for momelotinib. This experimental drug treats anaemic patients suffering from a bone marrow disease.

In January, data from a clinical trial in late stages showed it to be effective in relieving patients of blood transfusions and reducing symptoms.

The acquisition will complement GSK’s multiple myeloma treatment, Blenrep, GSK said. Myeloma, a form of blood cancer, is caused by cells found in the bone marrow and called plasma cells.