Health Canada has approved Pfizer’s Besponsa (inotuzumab ozogamicin for injection) for treating  adults with relapsed or refractory CD22-positive B-cell precursor acute lymphoblastic leukemia (ALL).

Besponsa is an CD22-directed antibody-drug conjugate.

ALL is a rare blood cancer. According to the Canadian Cancer Society, 480 Canadians, aged 15 years and older, were diagnosed with ALL in 2014 and 138 died of the condition in 2013. It is not known what percentage of ALL patients are CD22-positive B-cell precursor.

The approval of Besponsa was largely based on a randomized clinical trial in which 326 patients with relapsed or refractory B-cell ALL received Besponsa or an alternative chemotherapy regimen. In the Besponsa group, 35.8% had a complete remission (no evidence of disease and full recovery of blood counts) after a median of 8.0 months compared to 17.4% with a median of 4.9 months in the control group.

Most common adverse events with Besponsa include thrombocytopenia, neutropenia, leukopenia, infection, fatigue, severe bleeding, fever, nausea, headache, febrile neutropenia, liver damage, abdominal pain and hyperbilirubinemia.

In a news release, Andre Schuh, M.D., of Princess Margaret Cancer Centre in Toronto said, “Adults diagnosed with acute lymphoblastic leukemia face a poor prognosis, particularly if their disease has relapsed following prior treatment,” adding, “This Health Canada approval represents an important advancement for such patients, who until now have had limited options.”