GlaxoSmithKline (GSK) has agreed to acquire US-based late-stage biopharmaceutical firm Sierra Oncology for $1.9bn.

Sierra Oncology is engaged in developing targeted therapies to treat rare kinds of cancer.

Its differentiated therapy, momelotinib, can address the unmet medical needs of myelofibrosis patients with anaemia.

Momelotinib has inhibitory activity along key signalling pathways.

In January this year, Sierra Oncology unveiled positive topline data from the Phase III MOMENTUM clinal trial of momelotinib.

The data revealed that the trial met all the primary and key secondary endpoints and momelotinib offered a statistically significant and clinically meaningful benefit on symptoms, anaemia and splenic response.

GSK said that momelotinib complements its Blenrep (belantamab mafodotin), expanding the firm’s commercial and medical capabilities in haematology.

Furthermore, Sierra Oncology is planning to make a regulatory submission in the US in the second quarter and the European Union in the second half of this year.

In addition to momelotinib, Sierra Oncology’s pipeline includes two assets, SRA515 and SRA737, which are currently in the Phase I development stage.

The proposed acquisition is in line with GSK’s plans to build a strong portfolio of new speciality medicines and vaccines.

GSK chief commercial officer Luke Miels said: “Momelotinib offers a differentiated treatment option that could address the significant unmet medical needs of myelofibrosis patients with anaemia; the major reason patients discontinue treatment.

“With this proposed acquisition, we have the opportunity to potentially bring meaningful new benefits to patients and further strengthen our portfolio of speciality medicines.”

The transaction is anticipated to close in the third quarter of this year or earlier, subject to necessary conditions and approvals.

Last month, GSK signed a research and development collaboration with LifeMine Therapeutics to detect small molecule leads.