The combination of idelalisib and rituximab was highly active and resulted in durable disease control in treatment-naïve older patients with chronic lymphocytic leukemia (CLL), a new study published online ahead of print in the journal Blood has shown.1
Because idelalisib, a first-in-class oral PI3Kδ inhibitor, has shown substantial activity in patients with relapsed/refractory CLL, researchers sought to evaluate idelalisib as front-line therapy for older patients with CLL or small lymphocytic leukemia (SLL).
For the phase 2 study, researchers enrolled 64 previously untreated patients age 65 to 90 with CLL or SLL. All participants were treated with rituximab 375 mg/m2 intravenously weekly for 8 weeks plus idelalisib 150 mg orally twice daily continuously for 48 weeks. Individuals who completed 48 weeks of treatment without disease progression were eligible to participate in an extension study.
Results showed that after a median treatment duration of 22.4 months, the overall response rate was 100% in patients with del(17p)/T53 mutations and 97% in those with unmutated IGHV. At 36 months, progression-free survival was 83%.
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In regard to safety, the most frequent adverse events were diarrhea, rash, pyrexia, nausea, chills, cough, and fatigue. The most common lab abnormality was elevated ALT/AST, which occurred in 67% of patients.
“These results support the further development of idelalisib as initial treatment for CLL,” the authors concluded.
- O’Brien SM, Lamanna N, Kipps TJ, et al. A phase 2 study of idelalisib plus rituximab in treatment-naïve older patients with chronic lymphocytic leukemia [published online ahead of print October 15, 2015]. Blood. doi: 10.1182/blood-2015-03-630947.