AT ASH 2016
SAN DIEGO (FRONTLINE MEDICAL NEWS) – A chemotherapy-free induction regimen of ibrutinib and rituximab was well tolerated and achieved an overall response rate of 100% among patients with newly diagnosed mantle cell lymphoma (MCL), according to results of a small single-center phase II trial.
A total of 72% of patients had complete responses to induction, while 28% had partial responses, and 100% had complete responses to consolidation, reported Michael Wang, MD, at the annual meeting of the American Society of Hematology. The findings highlight a “window of opportunity” to effectively treat de novo MCL in young, fit patients while potentially sparing them from repeated cycles of intensive chemoimmunotherapy, the investigators noted.
Established treatments for MCL include eight cycles of rituximab–hyper-CVAD (hyper-fractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone) alternating with rituximab–methotrexate–Ara-C (cytarabine). Median overall survival with this regimen exceeds 10 years, but during that decade, more than 6% of patients will develop myeloid neoplasms related to treatment, noted Dr. Wang of the University of Texas MD Anderson Cancer Center in Houston.
For the study , patients up to 65 years old with newly diagnosed, untreated MCL underwent induction with continuous daily ibrutinib (560 mg), plus rituximab (375 mg/m2) administered weekly for 4 weeks during cycle 1 and on day 1 of cycles 3-12. Consolidation consisted of rituximab plus hyper-CVAD, alternating every 28 days with rituximab plus high-dose methotrexate–Ara-C. Complete responders to induction received four cycles of chemoimmunotherapy, while progressors and partial responders received chemoimmunotherapy for two cycles beyond the point of complete remission.
Among 36 evaluable patients, 28% had a partial response and the rest had complete responses to induction. Moreover, all 19 patients who completed consolidation had a complete response. During induction, the most common toxicities were fatigue, diarrhea, rash, and myalgia, nearly all of which were mild or moderate in severity. During consolidation, two patients developed severe neutropenia, one patient developed severe febrile neutropenia, and one developed a severe increase in liver enzymes. There were no treatment-related deaths.
“The toxicity after intensive immune-chemotherapy in shortened cycles [is] much improved compared to historical controls, but longer follow-up is needed,” the researchers wrote. “This unprecedented efficacy and safety may provide a window of opportunity for less chemoimmunotherapy needed for consolidation.”
Dr. Wang disclosed ties to Janssen, Onyx, BeiGene, Kite Pharma, Asana Biosciences, Juno Therapeutics, Acerta Pharma, and Celgene.