Rituximab therapy for hairy cell leukemia: a retrospective study of 41 cases

Refractory and relapsed hairy-cell leukemia (HCL): casting light on promising experimental drugs in clinical trials

INTRODUCTION

Hairy cell leukemia (HCL) is a rare subtype of indolent lymphoid leukemia originating from a mature B lymphocyte. The standard first-line treatment for classic HCL, and HCL variant (HCLv), consists of purine nucleoside analogs (PNA), with or without rituximab. However, almost half of patients relapse and require subsequent therapy.

AREAS COVERED

This article summarizes recent achievements in the treatment of relapsed and refractory HCL. A literature search was conducted of the PubMed and MEDLINE database for articles in English. Publications from 2010 through January 2023 were scrutinized. The search terms used were hairy cell leukemia in conjunction with BRAF inhibitors, Bruton's tyrosine kinase (BTK) inhibitors, CD20 monoclonal antibodies, relapsed, refractory and variant.The growing understanding of HCL biology has allowed the design of several new, chemotherapy-free targeted drugs which have demonstrated encouraging efficacy in early clinical trials.

EXPERT OPINION

Novel drugs will soon be available to assist standard therapy for HCL and HCLv among patients with suboptimal results following PNA treatment. In particular, the BRAF inhibitors vemurafenib and dabrafenib, with or without rituximab, have revolutionized treatment of patients with relapsed or refractory disease.

Prompt Hematological Recovery in Response to a Combination of Pegylated Interferon α-2a and Rituximab in a Profoundly Immuno-Suppressed Hairy Cell Leukemia Patient with a Mycobacterial Infection at Onset: Benefits and Drawbacks of Rapid Immune Reconstitution

The present paper reports, to the best of our knowledge for the first time, the efficacy and tolerability of the combination of interferon (IFN)α-2a in pegylated formulation and rituximab after a “priming” phase with IFN in the frontline treatment of hairy cell leukemia (HCL) in a profoundly immunosuppressed patient with a Mycobacterium abscessus infection at onset. This immunotherapy combination may represent a potential therapeutic option in patients with active severe infection and for whom the use of purine nucleoside analogues (PNA) is contraindicated. The benefits and drawbacks of remarkably rapid immune reconstitution in the context of opportunistic infections are highlighted as well, as the potentially paradoxical effects of immune recovery as a result of effective immunotherapy strategies, known as immune reconstitution inflammatory syndrome (IRIS), have to be taken into account when dealing with patients with opportunistic infections.

6-Morpholino- and 6-amino-9-sulfonylpurine derivatives. Synthesis, computational analysis, and biological activity

The synthesis of novel 6-chloro/morpholino/amino/-9-sulfonylpurine derivatives was accomplished in two ways, either (i) involving the condensation reaction of 6-chloropurine with commercially available arylsulfonyl chlorides in acetone and the presence of aqueous KOH at 0 °C, followed by the substitution of C6-chlorine with morpholine, or (ii) employing a reversed synthetic approach where 6-morpholinopurine and commercially available adenine bases were reacted with the corresponding alkyl, 2-arylethene and arylsulfonyl chlorides giving the N9 sulfonylated products, the latter particularly used where prior nonselective sulfonylation was observed. In both approaches, the sulfonylation reaction occurred regioselectively at the purine N9 position lacking any concurrent N7 derivatives, except in the case of a smaller methyl substituent on SO₂ and the free amino group at C6 of the purine ring. The tautomeric features of initial N9 unsubstituted purines, as well as stability trends among the prepared N-9-sulfonylpurine derivates, were investigated using DFT calculations with an important conclusion that electron-donating C6 substituents are beneficial for the synthesis as they both promote the predominance of the desired N9 tautomers and help to assure the stability of the final products. The newly synthesized 6-morpholino and 6-amino-9-sulfonylpurine derivatives showed antiproliferative activity on human carcinoma, lymphoma, and leukemia cells. Among the tested compounds, 6-morpholino 17 and 6-amino 22 derivatives, with trans-β-styrenesulfonyl group attached at the N9 position of purine, proved to be the most effective antiproliferative agents, causing accumulation of leukemia cells in subG0 cell cycle phase.

Skin changes in hairy cell leukemia

Skin lesions have been reported in about 10–12% of hairy cell leukemia (HCL) patients. Most are etiologically related to autoimmune or infectious processes, although secondary cutaneous neoplasms and drug-induced lesions are also reported. However, leukemia cutis with the direct infiltration of the skin by leukemic cells is extremely rare in HCL patients. This paper reviews the epidemiology, pathogenesis, clinical symptoms, diagnosis, and approach to treating skin lesions in HCL. A literature review of the MEDLINE database for articles in English concerning hairy cell leukemia, skin lesions, leukemia cutis, adverse events, infectious, cutaneous, drug reactions, neutrophilic dermatoses, secondary neoplasms, and vasculitis was conducted via PubMed. Publications from January 1980 to September 2020 were scrutinized. Additional relevant publications were obtained by reviewing the references from the chosen articles.

Bone lesions in hairy cell leukemia: Diagnosis and treatment

Skeletal involvement is a rare complication of hairy cell leukemia (HCL) with an incidence of approximately 3%. Bone lesions are commonly lytic, and the most common sites of involvement are the femoral head and neck. Skeletal involvement is typically associated with high tumor burden and bone marrow infiltration. However, isolated cases of skeletal disease without splenomegaly or bone marrow involvement are occasionally reported. This review focuses on skeletal lesions in HCL, particularly the pathogenesis, clinical symptoms, diagnostic methods, and treatment approach. A literature review of the MEDLINE database for articles in English concerning hairy cell leukemia, skeletal symptoms, bone involvement was conducted via PubMed. Publications from January 1970 to May 2020 were scrutinized. Additional relevant publications were obtained by reviewing the references from the chosen articles.

Moxetumomab pasudotox for the treatment of hairy cell leukemia

Introduction: Cladribine and pentostatin are the drugs of choice in the treatment of hairy cell leukemia (HCL). Recently, immunotoxin moxetumomab pasudotox has been introduced to improve the prognosis in relapsed and refractory HCL. Areas covered: This review discusses the mechanism of action, safety, and efficacy of moxetumomab pasudotox in HCL patients. A literature review of the MEDLINE database for articles in English concerning immunotoxins, moxetumomab pasudotox, and hairy cell leukemia was conducted via PubMed. Publications from 2000 through December 2018 were scrutinized. The search terms used were immunotoxins and moxetumomab pasudotox in conjunction with hairy cell leukemia. Conference proceedings from the previous five years of the American Society of Hematology, European Hematology Association and American Society of Clinical Oncology were searched manually. Additional relevant publications were obtained by reviewing the references from the chosen articles. Results/conclusion: Moxetumomab pasudotox, a novel recombinant anti-CD22 immunotoxin, was well tolerated and active in the previous phase 1 and 3 studies in patients with HCL. The drug has been approved in 2018 by the FDA for the treatment of patients with relapsed/refractory HCL who had at least two prior systemic therapies including at least one purine nucleoside analog. Expert opinion: The use of moxetumomab pasudotox is a promising new strategy for the treatment of HCL.

Hairy cell leukemia 2018: Update on diagnosis, risk-stratification, and treatment

Disease overview

Hairy cell leukemia (HCL) and HCL‐like disorders, including HCL variant (HCL‐V) and splenic diffuse red pulp lymphoma (SDRPL), are a very heterogeneous group of mature lymphoid B‐cell disorders, characterized by the identification of hairy cells, a specific genetic profile, a different clinical course and the need for appropriate treatment.

Diagnosis

Diagnosis of HCL is based on morphological evidence of hairy cells, an HCL immunologic score of 3 or 4 based on the CD11C, CD103, CD123, and CD25 expression, the trephine biopsy which makes it possible to specify the degree of tumoral medullary infiltration and the presence of BRAF V600E somatic mutation.

Risk stratification

Progression of patients with HCL is based on a large splenomegaly, leukocytosis, a high number of hairy cells in the peripheral blood and the immunoglobulin heavy chain variable region gene mutational status. VH4‐34 positive HCL cases are associated with poor prognosis

Risk adapted therapy

Purine analogs (PNA) are indicated in symptomatic first line HCL patients. The use of PNA followed by rituximab represents an alternative option.

Management of progressive or refractory disease

It is based on the use of BRAF inhibitors associated or not with MEK inhibitors, recombinant immunoconjugates targeting CD22 or BCR inhibitors.

Long-term durable remission by cladribine followed by rituximab in patients with hairy cell leukaemia: update of a phase II trial

Nucleoside analogues are highly active in patients with hairy cell leukaemia (HCL); however, patients continue to relapse. This phase II study evaluated the efficacy and safety of cladribine followed by rituximab in patients with untreated HCL (N = 59), relapsed HCL (N = 14) and HCL variant (HCLv, N = 7). Cladribine 5·6 mg/m(2) was given intravenously (IV) daily for 5 d and was followed approximately 1 month later with rituximab 375 mg/m(2) IV weekly for 8 weeks. Complete response rate in patients with untreated HCL, relapsed HCL and HCLv was 100%, 100% and 86%, respectively. With a median follow up of 60 months, 5-year failure-free survival (FFS) in patients with untreated HCL, relapsed HCL and HCLv was 95%, 100% and 64%, respectively. Median duration of response to the cladribine followed by rituximab was significantly longer than the first-line cladribine single agent in patients who received this treatment as second-line treatment (72 months vs not reached, P = 0·004). Almost all patients (94%) achieved negative minimal residual disease (MRD) after the treatment. Positive MRD during the follow up did not necessarily result in clinically relevant relapse. Cladribine followed by rituximab is highly effective even in patients with relapsed disease and HCLv, and can achieve durable remission.

Long-term follow-up after purine analogue therapy in hairy cell leukaemia

Since 2006 when we last reviewed the literature concerning the use of purine analogues in hairy cell leukaemia (HCL), results from several new and updated series have been published. Here we examine these reports and consider their implications for patient management. The two purine analogues pentostatin and cladribine remain the first-line treatments of choice for all patients with HCL. Although they have not been compared in randomised trials, they appear to be equally effective. A complete response is important for the long-term outcome and we look at how best this can be achieved. Evidence is emerging which supports the use of either purine analogue plus an anti-CD20 monoclonal antibody after relapse, though questions remain concerning the scheduling of the monoclonal antibody. Patients refractory to the purine analogues may require alternative agents.

New insights in the management of patients with hairy cell leukemia

PURPOSE OF REVIEW

Although hairy cell leukemia (HCL) was identified in 1958 by Bouroncle and colleagues, HCL remains in 2015 a mysterious disease. Accurate diagnosis of HCL relies on the recognition of hairy cells by morphology and flow cytometry in blood and/or bone marrow. However, there are cases difficult to diagnose, particularly in variants of HCL. Furthermore, some diseases such as splenic diffuse red pulp small B-cell lymphoma are very close to HCL and may be misdiagnosed. Major advances in the management of patients who have HCL have been made following the use of purine nucleoside analogs. However, new treatment options can be available in relapsed/refractory HCL: monoclonal antibody therapy, BRAF inhibitors, or immunotoxins.

RECENT FINDINGS

The presence of the BRAFV600E mutation was recently identified in most cases of HCL and its absence in variants of HCL and in other B-cell chronic lymphoproliferative disorders. The precise cellular origin of HCL remains elusive but BRAF mutations were detected in hematopoietic stem cells of patients with HCL. Assessment for minimal residual disease is important in clinical trials. Minimal residual disease detection can clearly predict inferior long-term outcomes or early relapses in patients with HCL. Recent reports have shown that inhibition of BRAF kinase by drugs such as vemurafenib is effective in relapsed/refractory HCL. Immunotoxins offer new opportunities even in patients without BRAF mutations.

SUMMARY

All these findings have major implications for diagnosis, monitoring, and treatment of HCL and variant forms of HCL.

Novel therapeutic options for relapsed hairy cell leukemia

The majority of patients with hairy cell leukemia (HCL) achieve a response to therapy with cladribine or pentostatin with or without rituximab. However, late relapses can occur. Treatment of relapsed HCL can be difficult due to a poor tolerance to chemotherapy, increased risk of infections and decreased responsiveness to chemotherapy. The identification of BRAFV600E mutations and the role of aberrant MEK kinase and Bruton's tyrosine kinase (BTK) pathways in the pathogenesis of HCL have helped to develop novel targeted therapies for these patients. Currently, the most promising therapeutic strategies for relapsed or refractory HCL include recombinant immunoconjugates targeting CD22 (e.g. moxetumomab pasudotox), BRAF inhibitors such as vemurafenib and B cell receptor signaling kinase inhibitors such as ibrutinib. Furthermore, the VH4-34 molecular variant of classic HCL has been identified to be less responsive to chemotherapy. Herein, we review the results of the ongoing clinical trials and potential future therapies for relapsed/refractory HCL.