(HealthDay News) — A new drug that targets interactions with the tumor microenvironment promotes remission in patients with relapsed chronic lymphocytic leukemia, according to a study published online June 19 in the New England Journal of Medicine.

As part of a phase 1b-2 study, John C. Byrd, M.D., from The Ohio State University in Columbus, and colleagues treated 85 patients with relapsed chronic lymphocytic leukemia with ibrutinib (PCI-32765) orally once a day, where 51 patients received 420 mg and 34 received 840 mg.

The researchers found that both groups had the same overall response rate of 71%. An additional 20% of the 420-mg group and an additional 15% of the 840-mg group had a partial response with lymphocytosis. The responses were independent of clinical and genomic risk factors. The estimated rate of progression-free survival was 75% and the estimated rate of overall survival was 83% at 26 months. Toxicity was largely grade 1 or 2, including diarrhea, fatigue, and upper respiratory tract infection.

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“Ibrutinib was associated with a high frequency of durable remissions in patients with relapsed or refractory chronic lymphocytic leukemia and small lymphocytic lymphoma, including patients with high-risk genetic lesions,” Byrd and colleagues conclude.

The study was partially funded by Pharmacyclics and Janssen Biotech, the manufacturers of ibrutinib.