A phase 1 clinical trial of flavopiridol consolidation in chronic lymphocytic leukemia patients following chemoimmunotherapy

Abstract

Patients with chronic lymphocytic leukemia (CLL) who receive chemoimmunotherapy and do not achieve complete remission experience significantly shortened progression-free interval (PFS). Additionally, the majority of patients treated for relapsed disease demonstrate evidence of measurable disease. Eradication of minimal residual disease (MRD) results in improved PFS and overall survival. Maintenance therapy might result in eradication of MRD and improve response duration but might be associated with an increase in incidence of infectious complications. Flavopiridol is a broad cyclin-dependent kinase (CDK) inhibitor with established safety and efficacy in patients with relapsed CLL, particularly patients with high-risk cytogenetic features. A pharmacologically derived schedule was utilized as consolidation therapy in this phase I study to assess the safety and feasibility of outpatient therapy with flavopiridol in patients with low tumor burden. Flavopiridol was administered as a 30-min loading dose of 30 mg/m(2) followed by a 4-h infusion of 30 mg/m(2) once weekly for 3 weeks every 5 weeks (1 cycle) for planned 2 cycles in ten patients. Therapy was extremely well tolerated and no patient developed acute tumor lysis syndrome. The most common toxicities were gastrointestinal. Of the patients, 22 % improved their response from a PR to CR. Eighty-eight percent experienced a reduction in tumor burden as measured by extent of bone marrow involvement including patients with del17p and complex karyotype. The study establishes the safety and efficacy of flavopiridol as consolidation therapy after chemoimmunotherapy for patients with CLL. Further evaluation is required in larger trials for the utility of CDK inhibitors as consolidation or maintenance strategies.Registration number at ClinicalTrials.gov: NCT00377104.

Keywords: Chronic lymphocytic leukemia; Flavopiridol.

Conflict of interest statement

Compliance with ethical standards

Conflict of interest The authors declare no relevant conflicts of interest except for research funding from Lymphoma Research Foundation, Leukemia and Lymphoma Society, and D Warren Brown Foundation.

Figures

Fig. 1

Pre- and post-treatment assessment of morphologic bone marrow involvement by CLL. Mean plasma concentration vs. time profiles for all 9 patients on C1D1 (left) and C1D8 (right).Each data point is mean plasma flavopiridol concentration ± standard deviation

Fig. 2

Kaplan–Meier curves of progression-free survival (solid line) and treatment-free survival (dashed line)

Fig. 3

Plasma flavopiridol concentration versus time. Mean plasma concentration vs. time profiles for all 9 patients on C1D1 (left) and C1D8 (right). Each data point is mean plasma flavopiridol concentration ± standard deviation