CHICAGO (FRONTLINE MEDICAL NEWS) – Acalabrutinib, which has shown efficacy in relapsed chronic lymphocytic leukemia, has now shown efficacy as a monotherapy for patients with previously untreated CLL, based on results from an ongoing phase I-II study presented as a poster at the annual meeting of the American Society of Clinical Oncology.

In a 74-patient study, best overall response rate was 96%, and median time to response was 2 months. CLL has not progressed in any of the patients, and none have experienced Richter’s transformation, Dr. John C. Byrd , the D. Warren Brown Chair of Leukemia Research at The Ohio State University, Columbus, and his colleagues reported. Based on its favorable safety profile and durable response rates, a phase III trial of acalabrutinib therapy has been initiated (NCT02475681).

Oral acalabrutinib was given at doses of 100 mg twice daily to 37 patients or 200 mg daily to 37 other patients. About half of the patients had bulky lymph nodes of at least 5 cm and 38 of 67 patients had an unmutated IGHV gene. Median time on the study was 11 months.

All patients had rapid declines in lymphadenopathy. Both dose schedules were associated with clinical activity, with Bruton’s tyrosine kinase occupancy highest at 98% with twice-daily dosing and 93% with once-daily dosing. Treatment-related lymphocytosis occurred in 39 of 74 patients and resolved in 38 of the 39. In general, lymphocytosis peaked at a median of 1 week and resolved by a median of 7 weeks.

Acalabrutinib was well tolerated with 72 of 74 patients continuing on the drug. Most adverse events were grade 2 or less, and included headache (42%), diarrhea (35%), arthralgia (22%), contusion (18%), nausea (18%) and increased weight (18%). Grade 3-4 adverse events that occurred in at least two patients included syncope (two patients) and hypertension (two patients). There was one grade 3 upper GI bleed from a gastric ulcer and aspirin use, and one grade 5 case of pneumonia. No atrial fibrillation was reported.

Dr. Byrd receives research funding from Acerta Pharma, the maker of acalabrutinib, as well as from Genentech and Pharmacyclics.

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