Ibrutinib – rituximab vs chemoimmunotherapy for chronic lymphocytic leukemia

This study aimed to investigate the effectiveness of ibrutinib–rituximab treatment compared to standard chemoimmunotherapy in patients aged 70 or younger with previously untreated chronic lymphocytic leukemia (CLL). 

This study concluded that the ibrutinib–rituximab regimen provided better outcomes compared to the standard chemoimmunotherapy for these patients.  

Standard chemoimmunotherapy for chronic lymphocytic leukemia (CLL) consists of fludarabine (Fludara), cyclophosphamide (Cytoxan) and rituximab (Rituxan). The combination of ibrutinib (Imbruvica) and rituximab has been used in trials for the treatment of CLL. The data comparing both treatment regimens is limited. 

It is not known which treatment regime is more effective in patients with CLL.  

This study involved 529 patients aged 70 or younger with previously untreated CLL. One group of 354 patients received ibrutinib and rituximab for six cycles, followed by ibrutinib until disease progression. The other group of 175 received six cycles of chemoimmunotherapy (fludarabine, cyclophosphamide, and rituximab). The main outcomes measured were progression-free survival (PFS; survival without cancer growing or spreading) and overall survival (OS). Patients were followed for an average of 33.6 months.

The 3-year PFS for the ibrutinib–rituximab group was 89.4% compared to 72.9% for the chemoimmunotherapy group. The 3-year OS rate was 98.8% for the ibrutinib–rituximab group compared to 91.5% for the chemoimmunotherapy group.  

In patients without immunoglobulin heavy-chain variable region (IGHV) mutation, the 3-year PFS rate was 90.7% for the ibrutinib–rituximab group compared to 62.5% for the chemoimmunotherapy group. In patients with the IGHV mutation, the 3-year PFS was 87.7% for the ibrutinib–rituximab group compared to 88% in the chemoimmunotherapy group.  

The frequency of severe side effects was 80.1% for the ibrutinib–rituximab group compared to 79.7% in the chemoimmunotherapy group. 10.5% of patients in the ibrutinib–rituximab group had infectious complications compared to 20.3% of patients in the chemoimmunotherapy group. 

This study concluded that the ibrutinib–rituximab regimen provided better PFS and OS compared to the standard chemoimmunotherapy for patients aged 70 and younger with previously untreated CLL. 

This study received partial support from Pharmacyclics, the manufacturer of ibrutinib.