Idelalisib plus rituximab: A suitable treatment for relapsed CLL?

This study examined the combination of rituximab (Rituxan) and idelalisib (Zydelig) for patients with relapsed chronic lymphocytic leukemia (CLL) and additional medical conditions. Researchers concluded that the combination of both treatments improved disease progression and survival when compared to rituximab alone.

Chemotherapy and immunotherapy are first-line treatments for CLL. Patients with a relapse (return of the disease) of CLL often have limited treatment options. Patients may develop resistance to previous chemotherapy or may continue to experience negative effects from a previous treatment. This is particularly true for elderly patients and those with additional medical conditions. Effective therapies with acceptable side-effect profiles are needed for this patient population.

Monoclonal antibody therapy is a type of immunotherapy that can lead to tumor cell death. Rituximab is a commonly used monoclonal antibody therapy. It is generally well-tolerated and often combined with other treatments. Idelalisib is a targeted therapy. Targeted therapies block molecules needed for cancer cell growth or spread. Early studies have shown it to be effective for relapsed CLL. Whether the combination of rituximab and idelalisib is safe and effective for relapsed CLL patients with other medical conditions has not been fully studied.

The aim of this study was to examine the safety and effects of this treatment combination for relapsed CLL patients with other medical conditions.

220 patients with relapsed CLL were included in this study. Patients had CLL that progressed within 2 years after the last treatment. The average time since diagnosis was 9 years. None of the patients were able to be treated with standard chemotherapy due to health reasons. 78% of patients were 65 years or older. 85% had additional medical conditions that were considered serious. Patients were randomly assigned to receive either rituximab plus idelalisib (group 1) or rituximab with placebo (control drug with no active effect, group 2). Average treatment time was 2.9 to 3.8 months.

93% of patients in group 1 were progression-free at 24 weeks. This was significantly higher compared to patients in the group 2 (46%). Overall, the risk of progression or death was 85% lower for patients in group 1. Results were similar for all patients, including those with genetic mutations (changes) that can affect treatment outcomes.

The overall survival rate (proportion who have not died from any cause since treatment) at 12 months was 92% for group 1. This was significantly higher compared to patients in group 2 (80%).

169 patients underwent imaging tests to examine the lymph nodes. 93% of patients in group 1 saw a reduction of at least 50% in lymph node involvement. This was significantly higher compared to patients in group 2 (4%).

Over 90% of patients experienced at least one side effect. Most were considered mild. In group 1, the most common were fever, fatigue, nausea, chills, and diarrhea. In group 2, common side effects included reactions at the time of injection, fatigue, cough, nausea, and difficulty breathing. At least one serious side effect occurred in 40% in group 1 and in 35% of group 2. These included pneumonia, fever, and low neutrophil (type of white blood cell) levels in the blood with fever.

Researchers concluded that the combination of rituximab and idelalisib improved disease progression and survival when compared to rituximab alone in patients with relapsed CLL.