An international study of ibrutinib in people with relapsed or refractory mantle cell lymphoma (MCL) continues to show unprecedented and durable results with few side effects.
A researcher from The University of Texas MD Anderson Cancer Center presented interim findings of the multi-center Phase 2 study earlier this week at the 54th American Society of Hematology Annual Meeting and Exposition.
The MCL study was the third of the meeting presented by MD Anderson faculty about ibrutinib. The others were in combination for chronic lymphocytic leukemia and by itself for relapsed or resistant follicular lymphoma.
"I believe we are witnessing a breakthrough in mantle cell lymphoma. This is great news for patients," said Michael Wang, M.D., associate professor in MD Anderson's Departments of Lymphoma and Myeloma and Stem Cell Transplantation and Cellular Therapy. Wang is lead author of the study.
Wang, director of the mantle cell lymphoma (MCL) program at MD Anderson, has spent the past 12 years researching the disease, including clinical trials of proteasome inhibitors, immune-modulating agents and an mTOR inhibitor.
"In a heavily treated relapsed or refractory population, oral ibrutinib induced a response rate as high as 70% - better than any other single agent ever tested in MCL," he said. "The response is durable with a long progression-free survival."
With a median follow-up period of 9.2 months for 110 patients, overall response rate was 68%, and complete remission rate was 22%.
Response was even more dramatic in the 51 original phase I clinical trial patients at a median of 15 months median on the study. Overall response rate was 75%, with 39% achieving complete remissions.
Overall response rate is partial responses plus complete remissions.
The drug blocks Bruton's tyrosine kinase, prominent on malignant immune system B-cells, causing cell death and decreasing cellular migration and adhesion in cancerous B-cells.
Pharmacyclics, Inc., which developed ibrutinib, sponsored the clinical trial. Wang and other study collaborators receive research funding from the company.
MD Anderson news release
ASH abstract no. 904