BY Kristie L. Kahl
Imbruvica (ibrutinib) may be superior to standard of care in elderly patients with untreated chronic lymphocytic leukemia (CLL), according to phase 3 findings published in the New England Journal of Medicine
– the most common form of leukemia in adults – mostly affects older individuals, with an average age at diagnosis of 70 years. Standard of care for this disease includes a combination of bendamustine, a type of chemotherapy, and Rituxan (rituximab), an immunotherapy agent that suppresses the immune system.
Imbruvica, a BTK inhibitor, first received Food and Drug Administration for the first-line treatment of patients with CLL approval in 2016; however, it has never been compared with chemoimmunotherapy in this setting. Therefore, the researchers conducted a phase 3 trial to evaluate the efficacy of Imbruvica, either alone (182 patients) or in combination with Rituxan (182 patients), compared with chemoimmunotherapy (183 patients) in individuals aged 65 or older with untreated CLL. Progression-free survival – or the time to disease worsening or death – served as the primary endpoint of the study.
The majority of patients were male (67 percent) at a median age of 71 years.
Median progression-free survival was reached only in the chemoimmunotherapy arm. Overall, 87 percent of patients receiving Imbruvica alone and 88 percent of those who received Imbruvica plus Rituxan were alive without any disease progression, compared with 74 percent of patients who received chemoimmunotherapy after two years. Of note, there was no significant difference between patients who received the monotherapy or combination regimen of Imbruvica.
In regards to overall survival, the researchers reported no significant difference between arms at a median follow-up of 38 months.
Patients who received the chemoimmunotherapy treatment reported the most grade 3 to 5 hematologic side effects (61 percent) compared with those who were treated with Imbruvica alone (41 percent) and in combination with Rituximab (39 percent). However, non-hematologic side effects were higher among those who received Imbruvica (74 percent each), compared with the chemoimmunotherapy (63 percent).
"Ibrutinib should become the new standard of care," senior study author Scott Smith, M.D., Ph.D., professor in the division of hematology/oncology, department of medicine of Loyola Medicine and Loyola University Chicago Stritch School of Medicine, said in a press release
, adding that additional studies of the agent in patients younger than 65 years