Imbruvica Plus Ublituximab Safely Improves Response Rate for High-Risk Chronic Lymphocytic Leukemia

The addition of ublituximab to Imbruvica (ibrutinib) demonstrated a better overall response rate in patients with relapsed or refractory high-risk chronic lymphocytic leukemia compared to Imbruvica alone, according to data published in The Lancet.

Previously, patients with chronic lymphocytic leukemia and high-risk features had poor outcomes with Imbruvica. Based on this, researchers sought to discover if there was a benefit to adding ublituximab to Imbruvica for this population.

“To our knowledge, this is the first randomized trial to show improvement in progression-free survival with the addition of an anti-CD20 agent (ublituximab) to (Imbruvica) in chronic lymphocytic leukemia, which could meaningfully affect treatment choices for this disease,” the study authors wrote.

This phase 3 study consisted of a total of 126 patients who were either assigned Imbruvica plus ublituximab (64 patients; median age, 66 years) or Imbruvica alone (62 patients; median age, 67 years). Imbruvica was given orally at a 420-milligram dose every day for all cycles. Ublituximab was given intravenously in 28-day cycles at varying doses.

After a median follow up of 41.6 months, the overall response rate (“defined as the proportion of patients who had a partial response, complete response or complete response with incomplete marrow recovery,” according to the study authors) was 83% in the group that received the combination treatment and 65% in those who received Imbruvica alone.

A complete response was observed in 19% of patients assigned the combination therapy compared with 5% assigned Ibruvica alone.

More patients achieved minimal residual disease negativity (meaning that no disease was detected after treatment) in the combination group than in the group that only received Imbruvica (42% versus 6%).

The safety analysis included 117 patients (59 patients in the combination group and 58 patients in the Imbruvica alone group) who received at least one dose f their assigned treatment. Most side effects were considered mild or moderate. The most common severe or life-threatening side effects were low white blood cell counts, (19% and 12%, respectively), anemia (8% and 9%) and diarrhea (10% and 5%). The most common serious side effects were pneumonia (10% and 7%, respectively), rapid heart rate (7% and 2%), severe response to infection (7% and 2%) and fever (5% and 2%). One death was considered to be treatment related, which was due to cardiac arrest in the Imbruvica alone group.

Limitations of this study include unknown long-term outcomes. “Despite these limitations, clinically meaningful improvements in overall response rate, complete response and (minimal residual disease) negative response were observed and translated into improved progression-free survival,” the study authors wrote. “These findings indicate the benefit of adding the next-generation anti-CD20 antibody ublituximab to (Imbruvica) in patients with relapsed and refractory high-risk chronic lymphocytic leukemia.”

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