Targeted therapy for treatment of patients with classical hairy cell leukemia

Hairy Cell Leukemia: Where Are We in 2023?

PURPOSE OF REVIEW

This article summarizes the current state of knowledge of hairy cell leukemia (HCL) regarding presentation, diagnosis, therapy, and monitoring, including perspectives on emergent therapies.

RECENT FINDINGS

Over the past decade, there has been enormous progress in the understanding of the biology of HCL which has led to the development of novel therapeutic strategies. The maturation of data regarding existing management strategies has also lent considerable insight into therapeutic outcomes and prognosis of patients treated with chemo- or chemoimmunotherapy. Purine nucleoside analogs remain the cornerstone of treatment, and the addition of rituximab has deepened and prolonged responses in the upfront and relapsed setting. Targeted therapies now have a more defined role in the management of HCL, with BRAF inhibitors now having a potential in the first-line setting in selected cases as well as in relapse. Next-generation sequencing for the identification of targetable mutations, evaluation of measurable residual disease, and risk stratification continue to be areas of active investigation. Recent advances in HCL have led to more effective therapeutics in the upfront and relapsed setting. Future efforts will focus on identifying patients with high-risk disease who require intensified regimens. Multicenter collaborations are the key to improving overall survival and quality of life in this rare disease.

Atraumatic Splenic Rupture as an Unusual Presentation of Hairy Cell Leukemia: A Case Report

Hairy cell leukemia (HCL) represents a rare B-cell malignancy with 2% of all leukemias and should be differentiated from HCL-like conditions, including HCL-variant (HCL-V) and splenic diffuse red pulp lymphoma (SDRPL). HCL gets its name from the short, thin projections that look like hair on its cells. It is associated with a specific immunophenotypic profile, cytopenia, and splenomegaly. Spontaneous splenic rupture can be a symptom of hematological malignancy such as HCL and is a life-threatening acute emergency. Here, we present a case of a 37-year-old man who presented to the hospital with signs of acute peritonitis and acute anemia and was found to have atraumatic splenic rupture secondary to splenomegaly. He underwent emergent angiography, where the bleeding splenic vessel was identified, and the patient was successfully treated with embolization. Immunophenotypic profile revealed that B-cells were positive for CD11c, CD103, CD25, and CD5, for which he received five days of cladribine and achieved complete clinical remission.

Hodgkin Lymphoma and Hairy Cell Leukemia Arising from Chronic Lymphocytic Leukemia: Case Reports and Literature Review

Richter’s syndrome represents the progression of chronic lymphocytic leukemia (CLL) to more aggressive diseases, most frequently diffuse large B-cell lymphoma, while Hodgkin’s lymphoma (HL) and hairy cell leukemia (HCL) are rarely described. The first case involved a 67-year-old man with a diagnosis of a high-risk stage-II CLL treated with rituximab and ibrutinib, developed a HL nodular sclerosis variant after three months of therapy for CLL. After achieving a complete remission for HL and ibrutinib cessation because of drug-related cardiotoxicity, the patient relapsed after five months off-therapy and died due to disease progression after two cycles of brentuximab-vedotin. The second case involved an 83-year-old female with a diagnosis of stage-IV CLL treated with rituximab plus bendamustine who developed a HCL eight years later. Pentostatin was unsuccessfully employed as upfront HCL therapy, and the patient was then switched to rituximab while in remission for CLL. In conclusion, Richter’s transformation risk rate might be higher in patients treated with novel targeted therapies, and multiparametric flow cytometry and lymph node biopsy at relapse could help in early identifying small clones. The treatment of predominant neoplasia is mandatory, and disease-specific drugs are administered; however, clinical efficacy might be lower in these patients.

Vemurafenib and Rituximab in Patients with Hairy Cell Leukemia Previously Treated with Moxetumomab Pasudotox

The purine nucleoside analogues cladribine and pentostatin are highly-active first-line therapeutic treatments for hairy cell leukemia (HCL), resulting in complete response rates of 80% to 90%. However, HCL patients continue to relapse, and sooner or later, most require subsequent lines of treatment. This report presents the cases of four relapsed patients with classic HCL who were treated with vemurafenib (mostly at the low dose of 240 mg twice daily for 16 weeks) combined with rituximab after the failure of several lines of therapy including cladribine with or without rituximab and moxetumomab pasudotox. Two patients achieved minimal residual disease negative complete response after combined treatment with vemurafenib and rituximab, with a hematologic response ongoing after 38 months from the end of treatment in one patient and a relapse of cytopenias occurring after 13 months in the other patient. A third patient normalized her blood counts and this hematologic response, which was not evaluated in the bone marrow at the end of treatment, was lost after 18 months. The last patient died due to infection and multi-organ failure, too early to verify response to vemurafenib. Two patients who had relapsed after vemurafenib and rituximab derived meaningful clinical benefit from retreatment with the same agents, but eventually relapsed again and started indefinite therapy with dabrafenib and trametinib leading to normalization of the blood counts (despite heavy bone marrow infiltration in the only patient so far evaluable in that regard). The outcomes of these cases indicate that novel targeted agents and, in particular, vemurafenib, combined with rituximab, improve the prognosis of HCL patients, even those heavily pretreated with PNAs and moxetumomab pasudotox.