AT MHM 2015

CHICAGO (FRONTLINE MEDICAL NEWS) – Adding ibrutinib to bendamustine and rituximab improved outcomes without significantly reducing safety in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) in the randomized, placebo-controlled, phase III HELIOS trial.

Efficacy results from the double-blind HELIOS trial, as reported by Dr. Asher Alban Chanan-Khan at the 2015 meeting of the American Society of Clinical Oncology, showed that adding ibrutinib to bendamustine and rituximab (BR) significantly extended progression-free survival, compared with BR plus placebo, in patients with CLL/SLL; the risk of progression and death was reduced by 80%.

The current findings, reported by Dr. Chanan-Khan at the American Society of Hematology Meeting on Hematologic Malignancies, demonstrate that this improvement was achieved without sacrificing safety, and they characterize the management of adverse events.

In 578 patients with active chronic CLL/SLL following at least one prior line of systemic therapy who were randomized to receive 420 mg of ibrutinib plus BR or placebo plus BR for six cycles, exposure was 14.7 months and 12.8 months, respectively. Infection rates were similar in the two groups, but exposure-adjusted analysis showed an overall lower infection rate in the ibrutinib group, compared with the placebo group (10.3/100 vs. 11.2/100 patient months), and the rates of grade 3 or higher infections was similar in the groups, said Dr. Chanan-Khan of the Mayo Clinic, Jacksonville, Fla.

The rates of all-grade and grade 3/4 anemia were 22.3% and 3.5%, respectively, in the ibrutinib group, and 28.9% and 8.0%, respectively, in the BR group. The ibrutinib patients also required fewer transfusions – most often red blood cell transfusions (23% vs. 29% in the BR group).This may have been a reflection of restoration of the hematopoietic system in the ibrutinib group, said Dr. Chanan-Khan.

Grade 3/4 neutropenia was similar in the groups (53.7% and 50.5%), but fewer patients discontinued treatment due to treatment-related neutropenia with ibrutinib (1% vs. 2.8%), he noted.

Thrombocytopenia occurred slightly more often in the ibrutinib group (30.7% vs. 24%), but grade 3/4 events occurred in 15% of patients in each group.

Atrial fibrillation (AF) occurred in a small number of patients, but was observed more often with ibrutinib (7.3% vs. 2.8% overall, and 2.8% vs. 0.7% for grade 3/4 AF). Only seven patients required dose interruption – for a median duration of 7 days – to manage AF.

“No dose reductions were required,” said Dr. Chanan-Khan, adding that four patients, all with grade 3/4 AF and all in the ibrutinib group, discontinued therapy because of AF.

“We then analyzed our data to identify potential risk factors for predisposition to AF … no one baseline risk factor could be identified as causative. However, most patients who developed AF had a known risk factor,” he said.

He added that among those with a prior history of AF, 28% on the ibrutinib arm, and only 9% on the placebo arm, developed AF.

Baseline cardiac comorbidities also were found to have no effect on progression-free survival in either arm.

“We therefore concluded that the risk of AF is low at around 5%, it does not impact progression-free survival, prior history of AF is not a contraindication in the absence of any great freak event, ibrutinib dose interruption or reduction is not warranted, and you should treat CLL patients first for CLL and manage AF second,” he said.

Another important factor that often impacts clinical decision making is the use of anticoagulants or antiplatelet agents and the bleeding risk with ibrutinib, he said, noting that more than 40% of patients in the ibrutinib arm were using such agents.

“We did not see any impact on the progression-free survival outcomes on either of the arms in patients who were on anticoagulant or antiplatelet therapy,” he said.

Bleeding occurred in 31% and 14.6% of patients in the ibrutinib and placebo groups, respectively, and most cases involved grade 1 bruises and contusions. Only four patients discontinued therapy because of bleeding.

The rates of grade 3/4 major bleeding and major hemorrhage events were low in both groups, at less than 4%, and two patients discontinued therapy because of major bleeding. Two patients in the ibrutinib arm died because of major bleeding, including one who had a large preexisting abdominal aortic aneurysm, and one who experienced a large postsurgical intestinal perforation.

“Overall, these data support the use of ibrutinib in patients on concurrent anticoagulant or antiplatelet therapy, with no significantly increased major risk of bleeding with ibrutinib vs. placebo, and most bleeding events being grade 1 in nature,” said Dr. Chanan-Khan.

The rate of treatment-related lymphocytosis – a known pharmacodynamic effect of ibrutinib – occurred in 7% and 5.9% of the ibrutinib and placebo group patients, and most cases resolved within 2 weeks.

Based on the results of the 2014 phase III RESONATE trial and others looking at ibrutinib as a single-agent treatment for CLL, the agent is considered a new standard of care in patients with previously treated CLL/SLL. HELIOS was the first study to investigate ibrutinib in combination with BR.

“Considering the significant improvement in progression-free survival and overall survival, ibrutinib has a strong overall risk-benefit profile,” Dr. Chanan-Khan concluded.

The HELIOS study was sponsored by Janssen Pharmaceuticals. Dr. Chanan-Khan reported having no disclosures.

sworcester@frontlinemedcom.com

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