Ibrutinib versus ofatumumab: Immunotherapy versus targeted therapy for relapsed or persistent CLL

This study compared the effectiveness of ibrutinib (Imbruvica) and ofatumumab (Arzerra) in treating relapsed or persistent chronic lymphocytic leukemia (CLL). Researchers concluded that ibrutinib improved survival and disease progression more than ofatumumab.

Chemotherapy and immunotherapy are usually the first-line treatment of CLL. In cases of a short relapse (return of the disease after a short period) of CLL, alternative treatment options are usually explored. This is because many patients develop a resistance to standard therapy over time.

Tyrosine kinase inhibitor therapy is a type of targeted therapy that blocks signals needed for tumors to grow. This type of therapy includes the Bruton tyrosine kinase inhibitor ibrutinib. Ibrutinib blocks a signal that keeps the CLL cell alive. Monoclonal antibody therapy is a treatment that uses antibodies that attach to cancer cells, killing them or making them unable to grow. Ofatumumab is an example of monoclonal antibody therapy. Both ibrutinib and ofatumumab can be effective in CLL that is hard to treat. Ibrutinib can be effective when there are certain genetic abnormalities. They may also be an effective treatment option for relapsed CLL.

The aim of this study was to compare ibrutinib and ofatumumab for relapsed CLL.

391 patients were included in this study. Patients had either relapsed or were no longer responding to standard therapy. They were randomly assigned to be treated with either ibrutinib or ofatumumab. Treatment outcomes were followed for an average of 9.4 months.

The time until disease progression was significantly longer in patients treated with ibrutinib. The average time to progression was 8.1 months for ofatumumab and over 9.4 months for ibrutinib. Overall, the risk of progression or death was 78% lower for patients treated with ibrutinib. At 6 months, 88% of patients treated with ibrutinib were still alive with no disease progression compared to 65% in the ofatumumab group. 57 patients in the ofatumumab group switched to ibrutinib after disease progression.

The 12-months overall survival rate (proportion who have not died from any cause since treatment) was 90% in the ibrutinib group. This was significantly greater compared to 81% in the ofatumumab group.

About 57% of patients in both groups had genetic abnormalities (a deletion of either the chromosome 17p13.1 or the chromosome 11q22.3). Among these patients, time to disease progression was also significantly longer with ibrutinib (over 9.4 months) compared to ofatumumab (average 5.8 months).

Average treatment duration was longer for ibrutinib (8.6 months) than for ofatumumab (5.3 months). 57% of the patients in the ibrutinib group and 47% of the patients in the ofatumumab group had at least one serious side effect. Diarrhea and irregular or fast heart rate were among the most common serious side effects. Ibrutinib was also associated with fatigue, fever, and nausea. Ofatumumab was associated with fatigue, reactions during infusion, and cough.

Researchers concluded that ibrutinib was more effective than ofatumumab for relapsed or persistent CLL.