The European Commission (EC) has approved Pfizer’s Besponsa (inotuzumab ozogamicin) for the treatment of adults with relapsed or refractory CD22-positive B-cell precursor acute lymphoblastic leukaemia (ALL) in the European Union (EU).

Approved as monotherapy, Besponsa is an antibody-drug conjugate (ADC) comprised of a monoclonal antibody (mAb) targeting CD22, a cell surface antigen expressed on cancer cells in almost all B-ALL patients, linked to a cytotoxic agent.

The treatment binds to the CD22 antigen on B-cells and is internalised into the cell where the cytotoxic agent calicheamicin is released to destroy the cell.

In addition, Besponsa can also treat adult patients with Philadelphia chromosome-positive (Ph+) and Philadelphia chromosome-negative (Ph-) relapsed or refractory B-cell precursor ALL.

Adults with Ph+ relapsed or refractory CD22-positive B-cell precursor ALL should have failed treatment with at least one tyrosine kinase inhibitor (TKI).

With the approval, the indication becomes the first and only antibody drug conjugate (ADC) available for the treatment of patients with this type of leukaemia in the EU.

Pfizer Oncology regional president Dr Andreas Penk said: "The EC’s approval of Besponsa represents an important milestone for patients, the oncology community, and Pfizer.

"This is the first approval for Besponsa and provides patients in the EU, who are battling an especially hard-to-treat leukaemia, with a new treatment option beyond chemotherapy."

Being an aggressive type of leukaemia, ALL can cause death to the patient within a few months if left untreated.

The EC approval is based on results from the Phase III INO-VATE ALL trial, in which 326 adult patients with relapsed or refractory B-cell precursor ALL were involved.

The study compared the Pfizer indication to chemotherapy, which is leukaemia's current standard of care.

The INO-VATE ALL trial involved two primary endpoints, complete response with or without hematologic recovery (CR/CRi), and overall survival (OS).