5-year data show deepening response with ibrutinib in CLL

This report on the 5-year experience with single-agent ibrutinib in chronic lymphocytic leukemia (CLL) is a step forward in knowledge of the drug’s natural history, according to Jennifer R. Brown, MD, PhD.

“Ibrutinib data are starting to mature, but much opportunity for growth remains,” Dr. Brown said in an editorial.

One notable update in the report is that a median, progression-free survival has been reached in patients with relapsed/refractory CLL. The reported 51-month median progression-free survival is “strikingly good” in this cohort of patients with high-risk disease, and compares favorably to older regimens in similar patient populations, she said.

Regarding previously untreated CLL patients, it is notable that 45% of this cohort discontinued treatment, many apparently after year 4, Dr. Brown said. The finding that median duration on therapy was just about 5.5 years in the cohort could be “potentially quite useful” in counseling patients, if confirmed in a larger cohort, she added.

Given the discontinuation data, one unanswered question is the durability of remission after stopping ibrutinib in a “deep but probably not complete remission” versus continuing therapy.

“Further follow-up of patients who discontinue without disease progression, as well as systematic investigation of time-limited therapy, including novel likely combination approaches, is clearly warranted,” Dr. Brown said in her editorial.

Dr. Jennifer R. Brown is with the Dana-Farber Cancer Institute in Boston. These comments are adapted an accompanying editorial ( Blood. 2018;131:1880-2 ). Dr. Brown reported ties to Janssen, Pharmacyclics, AstraZeneca, Sun, Redx, Sunesis, Loxo, Gilead, TG Therapeutics, Verastem, and AbbVie.