Prognostic Factors for Complete Response to Ibrutinib in Chronic Lymphocytic Leukemia

Key Points

  • Complete response was observed in 9.8% of patients, with median time to complete response of 14.7 months.
  • Factors associated with complete response were first-line treatment and absence of bulky disease.

In an analysis of two pooled studies reported in JAMA Oncology, O’Brien et al found that a complete response to ibrutinib (Imbruvica) in the treatment of chronic lymphocytic leukemia was more likely in patients receiving the agent as first-line therapy and in those without bulky disease.

Study Details

The study involved data from 327 patients receiving ibrutinib in a phase IB/II study (n = 132) and a phase III trial vs ofatumumab (Arzerra) in previously treated patients (n = 195). Patients  had a median age of 67 years, 69% were male, 57% had bulky disease (lymph node ≥ 5 cm), 56% had advanced-stage disease, and 56% had Eastern Cooperative Oncology Group performance status ≥ 1.

In total, 9.5% of patients received ibrutinib in the first-line setting, 11.6% had received one previous therapy, 24.8% had received two, and 54.1% had received at least three. Patients with relapsed or refractory disease had received a median of three. Median time on study was 26.4 months.

Factors Associated With Complete Response

A complete response was observed in 32 patients (9.8%), including 12 (11.9%) of 101 patients with relapsed or refractory disease and 8 (25.8%) of 31 treatment-naive patients in the phase IB/II trial and 12 (6.2%) of 195 previously treated patients in the phase III trial. Median time to complete response was 14.7 months (range = 4.6–47.1 months).

On univariate analysis, bulky disease, clinical stage, number of previous therapies, and β2-microglobulin level were significantly associated with the likelihood of complete response. On multivariate analysis, the only factors associated with increased likelihood of complete response were no previous therapy vs ≥ 1 previous therapy (odds ratio [OR] = 2.65, P = .047) and no bulky disease vs bulky disease (OR = 4.97, P = .001).

The investigators concluded, “Patients receiving ibrutinib as a first-line therapy for chronic lymphocytic leukemia and those without bulky disease had a better likelihood of [complete response] to treatment. The [complete response] rate with continued longer-term ibrutinib treatment was higher than in previous reports.”

The study was supported by Pharmacyclics LLC, an AbbVie Company.

Susan M. O’Brien, MD, of the Chao Family Comprehensive Cancer Center, University of California, Irvine, is the corresponding author for the JAMA Oncology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.