Difference of genomic copy numbers alterations between hairy cell leukemia-variant and classical hairy cell leukemia: a pilot retrospective study in Chinese

Protein profiling by reverse phase protein array (RPPA) in classical hairy cell leukemia (HCL) and HCL-variant

Classical hairy cell leukemia (HCL-c) and HCL variant (HCL-v) are recognized as separate entities with HCL-v having significantly shorter overall survival. Proteomic studies, shown to be prognostic in various forms of leukemia, have not been performed in HCL. We performed reverse phase protein array-based protein profiling with 384 antibodies in HCL-c (n = 12), HCL-v (n = 4), and normal B-cells (n = 5) samples. While HCL could be distinguished from normal based on unsupervised hierarchical clustering, overlap in protein expression patterns was seen between HCL-c and HCL-v, with ∼10% of the proteins being differentially expressed, suggesting potential therapeutic targets.

Purine nucleoside analogs plus rituximab are an effective treatment choice for hairy cell leukemia-variant

Both characteristics and optimal treatment strategy for hairy cell leukemia-variant (HCL-v) remain elusive due to its rarity. We retrospectively analyzed the clinical features of HCL-v and the efficacy of first-line treatment options in a large Chinese cohort. In this study, we recruited 33 HCL-v patients (23 males and 10 females) with a median age of 59 years (range, 34-79 years). The chief complaints included abdominal mass and relative signs (67%) and abnormal complete blood count (27%). Immunophenotyping showed monoclonal B-cells positive for pan B-cell antigens and CD11c, weakly positive for CD103 and CD200, while negative for CD5, CD10, CD25, CD123, and annexin A1. No BRAF V600E mutation was detected, but TP53 abnormality was recurrent. Treatment choices included interferon-α (IFN-α) in 11 patients, chlorambucil (CLB) in 5 patients, single purine nucleoside analogs (PNA) in 3 patients, PNA plus rituximab (PNA + R) in 9 patients, and others in 3 patients. Four patients who received IFN-α or CLB treatment also underwent splenectomy. Patients who received PNA + R had a higher complete response rate (88% versus 5%, P < 0.001) and longer progression-free survival (PFS, 3-year PFS rate 42% [95% CI 1-84] vs. 16% [95% CI 3-40], P = 0.042) than those who received other regimens. Overall, HCL-v is an indolent lymphoma with unique characteristics. The PNA + R regimen is the preferred choice in the first-line treatment for HCL-v.