Leukemia Drug Superior to Traditional Chemotherapy

Ibrutinib is significantly more effective than chlorambucil in chronic lymphocytic leukemia.

A recent phase 3 trial showed the superiority of a previously approved therapy for leukemia over standard chemotherapy.

The multi-center randomized study evaluated the kinase inhibitor ibrutinib (Imbruvica) in older untreated patients with chronic lymphocytic leukemia (CLL) compared with chlorambucil. The study, published in the New England Journal of Medicine, evaluated 269 patients with a median age of 72 years, of whom 44% had advanced stage disease.

Patients were randomized to receive either Imbruvica or chlorambucil with a median follow-up time of 18.4 months. Of the patients enrolled in the trial, 87% in the Imbruvica group were still on treatment at the time of analysis.

The results showed a 24-month overall survival rate of 97.8% in the Imbruvica group compared with 85.3% in the chlorambucil group, with minor adverse events reported.

"Ibrutinib was superior to chlorambucil in CLL patients with no prior treatment, as measured by progression-free survival, overall survival, and response,” said study lead Jan Burger, MD, PhD, from The University of Texas MD Anderson Cancer Center. "The study also revealed significant improvements in hemoglobin and platelet levels."

Imbruvica was previously approved by the FDA for the treatment of mantle cell lymphoma and in CLL patients who relapsed following prior treatment.

Imbruvica acts by attaching itself to Bruton's tyrosine kinase (BTK), which blocks BTK function, shuts down signal growth, and results in CLL cell death. The drug also stops tissue anchor signals on leukemia cells, and causes CLL cells to starve.

Side effects were reported in 20% of patients, including diarrhea, fatigue, cough, and nausea.

"CLL is the most common adult leukemia in western countries, and primarily affects older patients with a median age of 72 years at diagnosis," Dr. Burger said. "In many countries, chlorambucil has remained the standard first-line therapy for such patients since the 1960s. This study paves the way for the use of ibrutinib in the front-line therapy setting."