Current chemotherapy treatments for adults with newly diagnosed B-cell acute lymphoblastic leukemia (ALL) frequently lead to remission. In addition, it is common for patients to continue with lengthy chemotherapy treatments to stay in remission. But unfortunately, relapses often occur in patients, leading to poor survival rates.
Relapse of leukemia can even occur in many patients with no leukemia able to be found after they complete initial chemotherapy. A test of blood or bone marrow samples looks for low levels of cancer cells not killed by cancer treatment and not visible on other tests. Doctors refer to the test as 'minimal residual disease' or 'MRD.'
A recent research study led by the ECOG-ACRIN Cancer Research Group (ECOG-ACRIN) shows excellent results for patients who tested negative for MRD after initial treatment. The E1910 clinical trial found that adding an immunotherapy drug to chemotherapy kept most of this group of patients in remission and improved their survival. The drug is blinatumomab (BLIN-a-TOOM-oh-mab).
Why give blinatumomab to patients who are MRD-negative?
“We know that even though we can’t find leukemia in these patients’ bone marrow, it’s still hiding there,” says Mark Litzow, MD, of the Mayo Clinic in Rochester, Minnesota.
As Dr. Litzow explains, blinatumomab works by bringing a normal T cell close to a leukemia blast cell, killing it. T cells are important white blood cells that are part of the immune system. Blinatumomab already has two Food and Drug Administration (FDA) approvals for patients with B-cell ALL. The first is for people who experience a relapse after remission. The second is for those in remission who test positive for MRD.
“Patients who are MRD-negative have a better outlook than patients who are MRD-positive, generally, but they still relapse,” Dr. Litzow says. “We thought we could do better, so we wanted to see if blinatumomab would improve the results in this already somewhat favorable risk group, and the study showed that it did.”
The E1910 trial met its goal. Dr. Litzow explains: “After about 3.5 years of follow-up, 83% of the patients who went on to receive additional standard chemotherapy plus experimental blinatumomab were alive versus 65% of those who received chemotherapy only. So, we consider these results to be practice changing.”