CHICAGO, IL—Because of the significant benefit found in combining the targeted drug ibrutinib with standard chemotherapy for relapsed chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL), an interim analysis has closed the international HELIOS phase III clinical trial. These results were presented at the 2015 American Society for Clinical Oncology (ASCO) Annual Meeting.
Researchers found that ibrutinib and chemotherapy (bendamustine and rituximab [BR]) reduced the risk of death or cancer progression by almost 80% in patients with previously treated CLL or SLL, compared with BR alone.
“This finding represents a significant advancement in the management and treatment of this leukemia,” said presenter and HELIOS’ senior investigator Asher Chanan-Khan, MD, professor of medicine and chair of Hematology & Oncology, Mayo Clinic Cancer Center in Jacksonville, Florida. “Although CLL remains incurable, this new regimen offers longer disease control and a decreased risk of relapse for our patients.”
The HELIOS study, which enrolled 578 patients from centers around the world, was the first to compare, head-to-head, chemoimmunotherapy alone with chem-immunotherapy plus a targeted drug in patients with CLL.
CLL, the most common adult leukemia in the United States, is a B-cell cancer that is present in blood and lymph nodes. SLL is a B-cell cancer found only in lymph nodes.
Ibrutinib is an oral pill that blocks Bruton’s tyrosine kinase (BTR), making the cancer vulnerable to death. “This BTR inhibitor interrupts the cellular signaling path that drives B-cell growth and survival,” said Chanan-Khan.
Ibrutinib was approved by the US Food and Drug Administration (FDA) for the treatment of mantle cell lymphoma, a subset of B-cell lymphoma, in November 2013. It was also approved in February 2014 for the treatment of CLL, following a study of the agent alone in patients with very advanced disease who had been through multiple treatments.
The HELIOS trial was designed to test the two therapies in less heavily treated patients whose cancer had returned.
In the randomized study, 289 patients received ibrutinib plus BR, and the other 289 were treated with BR plus a placebo pill. At a median follow-up of 17.2 months, progression-free survival was significantly longer in the group who received the ibrutinib combination compared to those who did not.
The complete response rate was 10.4% in the BR/ibrutinib group and 2.8% in the BR group.
Overall response rate in the BR/ibrutinib group was 83% versus 68% in the group treated with BR alone. At the time of analysis (18 months), 79% of the patients receiving ibrutinib remained in remission versus only 24 who did not.