Researchers observed high response rates and continuous complete responses (CRs) in a long-term study of patients with symptomatic hairy cell leukemia (HCL) who received frontline cladribine. The results were published in Blood Advances.

“Cladribine is universally regarded as the frontline treatment of choice for symptomatic hairy cell leukemia, as it has transformed an almost incurable disease into a well-controllable condition,” the researchers wrote in their report. “The published international experience with frontline cladribine mainly consists of single-institution retrospective analyses, sometimes with a limited number of patients.”

The researchers reported on the long-term clinical experience of patients with HCL who were treated at 4 European centers between 1969 and 2018. Among patients requiring treatment for HCL who received frontline cladribine, responses were classified according to the Consensus Resolution criteria published in 1987. The primary outcomes were long-term overall survival (OS), disease-free survival (DFS), and progression-free survival (PFS) rates.

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The study included 384 patients with HCL. The median age at diagnosis was 56 (range, 25-85) years. The majority (87%) of patients were men. All patients received cladribine as frontline therapy. Most patients (54%) were treated between 2000 and 2009, followed by 27% between 2010 and 2019, and 18% between 1990 and 1999.

Across the centers, the overall response rate was 94% (range, 86%-100%). A CR was achieved in 72% of cases (range, 54%-85%), and 76% of patients did not require further treatment after the initial course of cladribine. Among patients achieving a CR, 54% experienced no further relapse or progression over time, with a median follow up of 8.5 years (range, 1-22 years). In addition, 20% of patients maintained a continuous CR (≥5 years), corresponding to 28% of all patients with a CR.

The median OS was 25 years, with 48% of patients alive at 28 years. The median PFS was 13 years, and the PFS rate was 43% at 22 years. The median DFS was 11 years, and the DFS rate was 26.5% at 22 years.

The 5-year PFS rate was 77%, and the 5-year DFS rate was 73%. At 10 years, the PFS and DFS rates were 58% and 51%, respectively. At 20 years, the PFS and DFS rates were 43% and 35%, respectively.

Cladribine was discontinued early in 18 cases due to hematologic toxicity (n=5), fever (n=5), sepsis (n=3), pneumonia (n=1), gastrointestinal bleeding (n=1), miliary tuberculosis (n=1), hepatic toxicity (n=1), and cutaneous rash (n=1). There were 4 deaths due to secondary neoplasms — lung adenocarcinoma (n=2), acute myeloid leukemia (n=1), and colon carcinoma (n=1).

“Besides reporting data on a significant number of patients treated homogeneously at 4 centers of excellence with experience in the management of HCL, this work displays the first international effort in collecting data on symptomatic HCL patients treated with upfront cladribine since its introduction in Europe with a long-term follow-up,” the study authors explained. “These results represent the everyday clinical practice with HCL patients at European sites, and outcomes reported for each participating center reflect the efficacy of cladribine as frontline treatment.”


Broccoli A, Argnani L, Cross M, et al. A 3-decade multicenter European experience with cladribine as upfront treatment in 384 patients with hairy cell leukemia. Blood Adv. 2022;6(14):4224-4227. doi:10.1182/bloodadvances.2022007854

This article originally appeared on Hematology Advisor