The novel agent blinatumomab more than doubled the complete response (CR) rate in patients with relapsed/refractory B-precursor acute lymphoblastic leukemia (ALL) compared with standard therapies.
Blinatumomab is a member of the BiTE (bispecific T-cell engager) drug class, a bispecific monoclonal antibody designed to direct the cytotoxic T-cells of the host’s immune system, via CD3, to attack CD19-expressing cancer cells.
In this open-label, single-arm, dose-ranging, phase 2 clinical trial, 25 patients with ALL were randomized to 1 of 3 doses of blinatumomab. Results for all tested doses showed that 68% (17) of the patients achieved a CR or a CR with partial hematologic recovery with blinatumomab.
For the 12 patients who received the dose selected for further investigation, 9 achieved a CR or partial hematologic recovery. All responders achieved minimal residual disease status, meaning that there were no detectable leukemic cells in their blood or bone marrow.
Treatment effect with blinatumomab was lasting, with a median complete hematologic remission of 7.1 months. At a median follow-up of 9.7 months, median survival time has not been reached. This ongoing measure already exceeds median survival times typically seen in ALL.
The most common adverse events observed were mild, predominantly flulike symptoms of fever and headache.
More serious, but reversible, events occurred in 7 patients and were managed with treatment interruption, after which all 7 patients continued the trial at event resolution.
“Blinatumomab as single agent induced an unprecedented high rate of complete hematological and minimal residual disease responses in adult patients with relapsed/refractory B-precursor ALL,” said the study’s lead investigator, Max S. Topp, MD, at Wuerzburg University Medical Center, Wuerzburg, Germany, where phase 2 studies are under way.—NC
