Single agent vemurafenib or rituximab-vemurafenib combination for the treatment of relapsed/refractory hairy cell leukemia, a multicenter experience

BACKGROUND

Hairy cell leukemia (HCL) is a rare mature B-cell malignancy that is primarily treated with purine analogues. However, relapse remains a significant challenge, prompting the search for alternative therapies. The BRAF V600E mutation prevalent in HCL patients provides a target for treatment with vemurafenib.

PATIENTS AND METHODS

This multicenter retrospective study included nine patients with relapsed/refractory (R/R) HCL from six different centers. Patient data included demographics, prior treatments, clinical outcomes, and adverse events.

RESULTS

Patients received different treatment regimens between centers, including vemurafenib alone or in combination with rituximab. Despite the differences in protocols, all patients achieved at least a partial response, with seven patients achieving a complete response. Adverse events were generally mild with manageable side effects. The absence of myelotoxic effects and manageable side effects make BRAF inhibitors attractive, especially for patients ineligible for purine analogues or those with severe neutropenia.

CONCLUSION

Single agent vemurafenib or in combination with rituximab appears to be a promising therapeutic option for R/R HCL. Further research is needed to establish standardized treatment protocols and to investigate long-term outcomes.

Clinical analysis of hairy cell leukemia: the rare indolent hematological malignancy

OBJECTIVE

To analyze the clinical features, diagnosis and treatment and prognosis of the rare hairy cell leukemia (HCL), in order to provide new references for the clinical and basic research of HCL.

METHODS

The clinical data of 17 patients with HCL admitted to Fujian Medical University Union Hospital, the Affiliated Hospital of Putian University and the First Affiliated Hospital of Gannan Medical University from January 1, 2016 to July 1, 2023 were collected and retrospectively studied, and the clinical features, diagnosis and treatment effects and prognosis of patients with HCL were analyzed. The Kaplan-Meier method was used for survival analysis. Meanwhile, the latest literature from PubMed was retrieved to systematically discuss the research progress in the diagnosis and treatment of HCL.

RESULTS

In this study, there were 11 males and 6 females, the median age at diagnosis was 59.5 (30-81) years old, and the median time from the onset of clinical symptoms or signs to diagnosis was 4.5 (0.5-28.5) months. There were 9 cases (52.94%) with lymphoma B symptoms (fever, night sweating, and weight loss), 15 cases (88.24%) were accompanied by splenomegaly (3 cases of mild splenomegaly, 4 cases of moderate splenomegaly, and 8 cases of megasplenomegaly), the positive rate of BRAFV600E mutation is 76.47% (13/17). All patients in this study were treated, of which 11 were treated with Cladribine, 3 with Interferon, 2 with FC regimen, and 1 with R-CVP regimen + Cladribine. The median follow-up time was 39 (range, 2-83) months, 3 patients died, all due to failure of chemotherapy due to disease progression. The prognosis of HCL-v patients was significantly worse than that of cHCL patients (P=0.01), and there was no significant difference in the impact of different treatment regiments on the OS of HCL patients (P=0.328).

CONCLUSION

HCL is a rare clinically indolent hematological tumor, which is sensitive to Cladribine, with the emergence of precision treatments such as the novel molecular-targeted drugs and immunotherapy also plays an indispensable role in clinical practice of HCL.

A case report and literature review

Hairy cell leukemia (HCL) is a rare lymphoproliferative disorder classically presenting with cytopenia and recurrent infections but atypical manifestations such as bone lesions, skin lesions and effusion have been described. We report here an unusual meningeal localization in a 33 years old man who presented with headache, hand paresthesia and visual symptoms. Brain magnetic resonance imaging revealed an occipital meningeal lesion. Diagnostic explorations led to the diagnosis of classical HCL with meningeal localization. After treatment by cladribine and rituximab the patient rapidly improved and is still in complete remission 12 months after end of treatment. The literature review identified 9 other cases of HCL with central nervous system localization (CNS) presenting with brain parenchyma and/or meninges localization. Four out of 9 patients presented with hyperleukocytosis. Most patients experienced good responses with various treatments. Cladribine alone or with rituximab led to complete responses similar to our patient. In our patient, molecular biology revealed KLF2 mutations, which implication in the atypical localization could be suspected but would need dedicated studies. In conclusion, CNS localizations of HCL are rare but can be observed and treatment with cladribine alone or with rituximab appears as an effective strategy.

BRAF(V600E) mutation together with loss of Trp53 or pTEN drives the origination of hairy cell leukemia from B-lymphocytes

Hairy cell leukemia (HCL) is a B-lymphoma induced by BRAF(V600E) mutation. However, introducing BRAF(V600E) in B-lymphocytes fails to induce hematological malignancy, suggesting that BRAF(V600E) needs concurrent mutations to drive HCL ontogeny. To resolve this issue, here we surveyed human HCL genomic sequencing data. Together with previous reports, we speculated that the tumor suppressor TP53, P27, or PTEN restrict the oncogenicity of BRAF(V600E) in B-lymphocytes, and therefore that their loss-of-function facilitates BRAF(V600E)-driven HCL ontogeny. Using genetically modified mouse models, we demonstrate that indeed BRAF(V600E)KI together with Trp53KO or pTENKO in B-lymphocytes induces chronic lymphoma with pathological features of human HCL. To further understand the cellular programs essential for HCL ontogeny, we profiled the gene expression of leukemic cells isolated from BRAF(V600E)KI and Trp53KO or pTENKO mice, and found that they had similar but different gene expression signatures that resemble that of M2 or M1 macrophages. In addition, we examined the expression signature of transcription factors/regulators required for germinal center reaction and memory B cell versus plasma cell differentiation in these leukemic cells and found that most transcription factors/regulators essential for these programs were severely inhibited, illustrating why hairy cells are arrested at a transitional stage between activated B cells and memory B cells. Together, our study has uncovered concurrent mutations required for HCL ontogeny, revealed the B cell origin of hairy cells and investigated the molecular basis underlying the unique pathological features of the disease, with important implications for HCL research and treatment.

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.

A cyanine-based NIR fluorescent Vemurafenib analog to probe BRAFV600E in cancer cells

BRAF represents one of the most frequently mutated protein kinase genes and BRAF^V600E mutation may be found in many types of cancer, including hairy cell leukemia (HCL), anaplastic thyroid cancer (ATC), colorectal cancer and melanoma. Herein, a fluorescent probe, based on the structure of the highly specific BRAF^V600E inhibitor Vemurafenib (Vem, 1) and featuring the NIR fluorophore cyanine-5 (Cy5), was straightforwardly synthesized and characterized (Vem-L-Cy5, 3), showing promising spectroscopic properties. Biological validation in BRAF^V600E-mutated cancer cells evidenced the ability of 3 to penetrate inside the cells, specifically binding to its elective target BRAF^V600E with high affinity, and inhibiting MEK phosphorylation and cell growth with a potency comparable to that of native Vem 1. Taken together, these data highlight Vem-L-Cy5 3 as a useful tool to probe BRAF^V600E mutation in cancer cells, and suitable to acquire precious insights for future developments of more informed BRAF inhibitors-centered therapeutic strategies.

Untangling the Strands of Hairy Cell Leukemia: The Clinicopathological Spectrum over Eleven Years at a Tertiary Care Center

BACKGROUND

Hairy Cell Leukemia (HCL) is an uncommon, indolent lymphoproliferative disorder of mature B lymphoid cells, accounting for 2% of all lymphoid tumors. The present study evaluated the clinical-hematological profile of HCL patients diagnosed at a single tertiary care center over a 11-year period.

METHODS

The retrospective observational study was done between October 2010 and September 2021. The relevant clinical and laboratory information were retrieved from hospital medical records and electronic databases. The statistical analysis was performed using version 23.0 of SPSS.

RESULTS

66 (5.9%) of 1125 cases of chronic lymphoproliferative disorder were HCL. Splenomegaly was found in 47 (71.2%), hepatomegaly in 26 (39.5%), and lymphadenopathy in 17 (25.7%) of the cases. The mean hemoglobin, total leukocytes count, and platelets count were 8.04 g/dl, 6.76 X 109/L, and 77 X 109/L, respectively. Pancytopenia was detected in 40 cases (60.61 %). Bone marrow biopsies were majorly hypercellular and showed predominantly diffuse infiltration by atypical lymphoid cells. In two patients, initially thought of having refractory/hypoplastic anemia, the bone marrow biopsy and flow cytometry revealed HCL involvement.  42 cases of HCL underwent flow cytometry. CD20, CD 11c, CD 25 and CD 103 were positive in all the cases. The aberrant expression of CD5, CD10, and CD23 was found in frequencies of 5.71 %, 31.42 %, and 19.35%, respectively. In 40 cases for which follow-up information was available, there was full remission in 26 patients (65%), and later three showed relapse (7.5%) of which one died, and persistent leukemic activity in five (10%).  Eight patients (20%) died even before the initiation of treatment. One patient died within one month of therapy. No patient was examined for BRAF V600E mutation analysis.

CONCLUSION

CD 10+ HCL was the most prevalent atypical immunophenotypic subgroup. Bone marrow biopsy and flow cytometry are crucial diagnostic tools to rule out hairy cell leukemia. However, BRAF V600E mutation analysis should be performed in cases with unusual presentation or resistance to treatment.

Unusual presentation of gastric cancer during treatment of hairy cell leukemia: Exploring the etiological basis of this rare phenomenon

Hairy cell leukemia (HCL) is a rare B-cell lymphoproliferative disorder. Patients typically present with cytopenia and splenomegaly. We describe the case of a 78-year-old patient with refractory HCL who acutely developed a cystic lesion on the back while receiving moxetumomab pasudotox therapy. Biopsy of the lesion revealed the presence of adenocarcinoma, which prompted a detailed evaluation resulting in a diagnosis of stage IV gastric cancer. Nevertheless, to establish any association between moxetumomab pasudotox therapy and secondary cancer development, a satisfactory number of studies need to be conducted.

Long-term follow-up of patients with hairy cell leukemia in the south of Iran

BACKGROUND

Hairy cell leukemia (HCL) is an indolent chronic lymphoproliferative disorder and first-line treatment with either intravenous or subcutaneous cladribine generally leads to long-lasting remissions.

METHOD

All 131 patients with hairy-cell leukemia (HCL) were analyzed, with a median follow-up of 91 months. Data is from 2007 to 2020. We evaluated the response rate to cladribine as the first line and the response rate to cladribine with or without rituximab in relapsed patients. Further, we assessed relapse-free survival, complications, and secondary malignancy.

RESULTS

After a median follow-up of 91 months, the recurrence rate was 24%. The 5-year and 10-year RFS rates were 85% and 66%, respectively. Adding rituximab to 2-CDA leads to a better response rate than just cladribine (90% vs. 27.3%, p-value = 0.002) in the relapsed patients.

CONCLUSION

HCL patients have long-term survival when cladribine is the first line of treatment. Furthermore, adding rituximab to cladribine leads to a higher response rate.

Cladribine Efficacy in a Patient with Hairy Cell Leukemia and Severe Renal Insufficiency

BACKGROUND

Hairy cell leukemia commonly presents with pancytopenia, indolent course, and predisposition as infectious complications. Current first-line therapeutic options are purine analogues, particularly cladribine, with a high percentage of complete responses and durable remissions. However, their use is poorly investigated in patients affected by severe chronic renal insufficiency.

CASE PRESENTATION

Here, we describe a case of HCL in a 68-year-old man affected by multiple comorbidities, including severe chronic renal failure. After a course of interferon-α, the patient received therapy with Cladribine every other week, obtaining a complete hematological remission and improvement of renal function.

DISCUSSION

With a different soft schedule of cladribine, the patient was treated adequately, obtaining a complete remission.

CONCLUSION

Cladribine can be administered with caution, even in patients with renal failure, with good results.

Novel targeted treatments in hairy cell leukemia and other hairy cell-like disorders

In the category of mature B-cell neoplasms, splenic B-cell lymphoma and leukemia were clearly identified and include four distinct entities: hairy cell leukemia (HCL), splenic marginal zone lymphoma (SMZL), splenic diffuse red pulp lymphoma (SDRPL) and the new entity named splenic B-cell lymphoma/leukemia with prominent nucleoli (SBLPN). The BRAF^V600E mutation is detected in nearly all HCL cases and offers a possibility of targeted therapy. BRAF inhibitors (BRAFi) represent effective and promising therapeutic approaches in patients with relapsed/refractory HCL. Vemurafenib and dabrafenib were assessed in clinical trials. The BRAF^V600E mutation is missing in SDRPL and SBLPN: mitogen-activated protein kinase 1 (MAP2K1) mutations were found in 40% of SBLPN and VH4-34+ HCL patients, making possible to use MEK inhibitors (MEKi) such as trametinib, cobimetinib or binimetinib in monotherapy or associated with BRAFi. Other mutations may be associated and other signaling pathways involved, including the B-cell receptor signaling (BCR), cell cycle, epigenetic regulation and/or chromatin remodeling. In SDRPL, cyclin D3 (CCND3) mutations were found in 24% of patients, offering the possibility of using cell cycle inhibitors. Even if new emerging drugs, particularly those involved in the epigenetic regulation, have recently been added to the therapeutic armamentarium in HCL and HCL-like disorders, purine nucleoside analogs more and more associated with anti-CD20 monoclonal antibodies, are still used in the frontline setting. Thanks to the recent discoveries in genetics and signaling pathways in HCL and HCL-like disorders, new targeted therapies have been developed, have proven their efficacy and safety in several clinical trials and become essential in real life: BRAFi, MEKi, Bruton Tyrosine Kinase inhibitors (BTKi) and anti-CD22 immunotoxins. New other drugs emerged and have to be assessed in the future. In this article, we will discuss the main mutations identified in HCL and HCL-like disorders and the signaling pathways potentially involved in the pathogenesis of the different hairy cell disorders. We will discuss the results of the recent clinical trials, which will help us to propose an algorithm useful in clinical practice and we will highlight the different new drugs that may be used in the near future.

Increased risk of severe cutaneous adverse reactions when cladribine is used together with other medications with a propensity for skin reactions

Cladribine is a purine analog used in first-line treatment of hairy cell leukemia and in relapsed/refractory chronic lymphocytic anemia. Although cladribine is typically associated with mild, self-limited skin reactions, there is increasing evidence that cladribine may increase the risk of severe cutaneous adverse reactions (SCAR) when combined with drugs classically associated with SCAR (e.g. allopurinol) beyond what would be expected for either drug alone, possibly due to cladribine-induced lymphopenia. We analyzed all SCAR cases reported for cladribine in Janssen's Global Safety Database and found that 26/35 (74.3%) reported concomitant drugs known to be associated with SCAR, most commonly sulfamethoxazole/trimethoprim (SMX/TMP) and allopurinol. In addition, a review of the WHO VigiBase showed that several drugs, including penicillins, SMX/TMP, and allopurinol had a statistically significant contribution to cladribine-associated SCAR. These results lend further support that cladribine may increase the propensity of these drugs to cause SCARs.

Retrospective Evaluation of Hairy Cell Leukemia Patients: Analysis of a Long-Term Single Center Data

Background: Hairy cell leukemia (HCL) is a distinct lymphoproliferative disorder with unique circulating lymphocyte morphology. It is now regarded as an indolent disease yet treatable with purine analogs. We are going to present a complete long-term clinical and prognostic report of our HCL patients as a large cohort in Iran. Materials and Methods: All patients diagnosed with HCL, according to the World Health Organization (WHO) criteria, were enrolled in this study. They were referred to our academic center between 1995 and 2020. Treatment with a daily cladribine regimen was initiated as indicated and patients were followed. Survival data and clinical outcomes of patients were calculated. Results: A total of 50 patients were studied (76% male). The median time to treatment was 4.8 months and complete remission was achieved in 92% of patients. Nine patients (18%) experienced relapse with a median time to relapse of 47 months. After a median follow-up of 51 months, the median OS was not reached and after 234 months, the overall survival rate was 86%. Survival was worse in patients with non-classic HCL (vHCL) compared to classic HCL. Conclusion: Our long-term follow-up data confirmed the favorable outcomes of Iranian HCL patients with cladribine and provide a useful viewpoint of the disease.

Patient-driven research: Initial results from a prospective health-related quality of life study performed at the request of patients living with hairy cell leukemia

A diagnosis of leukemia can have a profound effect on patients' health-related quality of life (HRQoL), however this has not been measured prospectively in patients with hairy cell leukemia (HCL). At the request of patients living with HCL who had identified this gap in knowledge about the disease, we conducted a longitudinal study of HRQoL among patients enrolled in the HCL Patient Data Registry (PDR). From September 1, 2018 to September 1, 2020, 165 patients were enrolled in the study and completed the baseline survey. The Functional Assessment of Cancer Therapy - Leukemia (FACT-Leu) was used to measure patients' HRQoL. Results show that newly diagnosed HCL patients reported the lowest HRQoL, followed by patients in relapse and those on "watch and wait." Factors associated with higher (better) FACT-Leu total scores in the multivariable analysis included older age, higher social support, and greater physical activity. These same factors were associated with lower levels of fatigue. In rare diseases where it is difficult to perform large prospective studies, patient/researcher collaborations are critical for the identification of studies that are of importance to patients and their families in order to maximize the benefits of the research and improve the lives of patients living with HCL.

A Method for the Elution of Anti-CD20 With an EDTA/Glycine Acid Solution for Accurate Immunophenotyping of B Lymphocytes Sensitized With Rituximab

OBJECTIVES

To assess the efficacy of a method to circumvent CD20-positive antigen masking by rituximab for flow cytometry analysis of B-cell malignancies in hematology patients.

METHODS

Mononuclear cells (MNCs) from 10 healthy individuals and 5 untreated patients with B-cell malignancies were sensitized with rituximab. Patients' diagnoses included chronic lymphocytic leukemia, hairy cell leukemia, and follicular lymphoma. MNCs were isolated by gradient density centrifugation. An EDTA/glycine acid (EGA) elution method was used to dissociate CD20-rituximab complexes; afterwards, CD20-positive immunoreactivity was assessed by flow cytometry. A saturation curve was built based on serial dilutions of rituximab. Median fluorescent intensities of CD20-positive signals were obtained before sensitization with rituximab and after its elution with EGA.

RESULTS

CD20-positive signals were not detectable by flow cytometry after rituximab sensitization of B cells. CD20-sensitized vs CD20-unsensitized, CD20-sensitized vs CD20-eluted, and CD20-eluted vs CD20-negative control (NC) MNC populations exhibited statistical differences (P = .001), while CD20-sensitized vs CD20-NC populations did not (P = .499), confirming CD20 antigen masking by rituximab.

CONCLUSIONS

Rituximab interfered with the flow cytometry protocol for CD20 determination on normal and neoplastic B cells. The EGA method efficiently eluted rituximab, allowing for accurate identification of CD20-positive B cells.

Hairy cell leukemia: a specific 17-gene expression signature points to new targets for therapy

Background

Hairy cell leukemia (HCL) is a rare chronic B cell malignancy, characterized by infiltration of bone marrow, blood and spleen by typical “hairy cells” that bear the BRAFV600E mutation. However, in addition to the intrinsic activation of the MAP kinase pathway as a consequence of the BRAFV600E mutation, the potential participation of other signaling pathways to the pathophysiology of the disease remains unclear as the precise origin of the malignant hairy B cells.

Materials and methods

Using mRNA gene expression profiling based on the Nanostring technology and the analysis of 290 genes with crucial roles in B cell lymphomas, we defined a 17 gene expression signature specific for HCL.

Results

Separate analysis of samples from classical and variant forms of hairy cell leukemia showed almost similar mRNA expression profiles apart from overexpression in vHCL of the immune checkpoints CD274 and PDCD1LG2 and underexpression of FAS. Our results point to a post-germinal memory B cell origin and in some samples to the activation of the non-canonical NF-κB pathway.

Conclusions

This study provides a better understanding of the pathogenesis of HCL and describes new and potential targets for treatment approaches and guidance for studies in the molecular mechanisms of HCL.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-022-04010-4.

Long-term outcomes of elderly hairy cell leukemia patients treated with cladribine

Hairy cell leukemia (HCL) is a rare hematologic disorder characterized by pancytopenia and splenomegaly for which a single course of cladribine is highly effective in inducing complete remissions. However, there is limited real-world data on outcomes and complications among geriatric patients with HCL treated with cladribine. We conducted a retrospective review of all patients 70 years or older within the Scripps Clinic HCL Database at the time of first treatment with cladribine. Of the 45 patients meeting inclusion criteria, 32 (71%) achieved CR and 4 (9%) achieved PR. Of the 9 remaining patients, 7 achieved normalization of peripheral blood counts after a single course of cladribine (complete hematologic response, CHR) and 2 had no response. The median duration of response for all responders was 119 months. Nine (20%) patients relapsed with a median time to first relapse of 28 months. Ten patients subsequently developed 12 primary malignancies with an excess frequency (observed-to-expected ratio) of 0.85 (95% confidence interval, 0.48-1.49). Median overall survival for the entire cohort was 166 months from time of HCL diagnosis and 119 months from time of first cladribine administration. Forty patient deaths were observed; the standardized mortality ratio (observed-to-expected ratio) was 1.42 (95% confidence interval, 1.03-1.96), representing a statistically significant increase in the risk of death (P = .03). This study supports the high rate of complete and durable responses following a single course of cladribine in geriatric patients.

Advances in the Treatment of Hairy Cell Leukemia Variant

OPINION STATEMENT

Hairy cell leukemia variant (HCL-V) is a rare B cell lymphoproliferative disorder with a clinical-pathological distinction from the classic form of hairy cell leukemia (HCL-C). HCL-V is more aggressive in nature, has a higher tendency to be refractory to conventional purine analog pharmacotherapies, and leads to a poorer prognosis. Hence, these differing features bring paramount importance to the diagnosis and management of HCL-V. While there is no genetic mutation diagnostic of HCL-V, genetic profiling efforts have identified potential therapeutic targets (i.e., MAP2K1, KDM6A, CREBBP, ARID1A, CCND3, U2AF1, KMT2C) and yielded prognostic markers (i.e., IGHV4-34 rearrangements). To date, combination chemoimmunotherapies, such as cladribine and rituximab, have shown the best results in HCL-V. Future directions include targeted therapies such as moxetumomab pasudotox, ibrutinib, trametinib, and binimetinib and potentially anti-CD22 chimeric antigen receptor T cell therapy. The purpose of this review is to provide an outline of the diagnostic approach and an update on the therapeutic advancements in HCL-V.

Diagnosis and treatment of hairy cell leukemia as the COVID-19 pandemic continues

Hairy cell leukemia (HCL) is an indolent B-cell malignancy, usually driven by the BRAF V600E mutation. For 30 years, untreated and relapsed HCL was successfully treated with purine analogs, but minimal residual disease (MRD) remained in most patients, eventually causing relapse. Repeated purine analogs achieve decreasing efficacy and increasing toxicity, particularly to normal T-cells. MRD-free complete remissions (CRs) are more common using rituximab with purine analogs in both 1^st-line and relapsed settings. BRAF inhibitors and Ibrutinib can achieve remission, but due to persistence of MRD, must be used chronically to prevent relapse. BRAF inhibition combined with Rituximab can achieve high MRD-free CR rates. Anti-CD22 recombinant immunotoxin moxetumomab pasudotox is FDA-approved in the relapsed setting and is unique in achieving high MRD-free CR rates as a single-agent. Avoiding chemotherapy and rituximab may be important in ensuring both recovery from COVID-19 and successful COVID-19 vaccination, an area of continued investigation.

Rituximab Treatment of Hairy Cell Leukemia in a Patient with Mycobacterium kansasii Infection: A Case Report

INTRODUCTION

Infectious complications represent a major cause of morbidity and mortality in hairy cell leukemia (HCL) patients. Due to the immunosuppressive nature of the disease, these patients are frequently affected by opportunistic infections and rare pathogens. Furthermore, cytotoxic chemotherapy might lead to poor or even fatal outcomes in the setting of an active infection.

CASE PRESENTATION

We report the case of a 62-year-old HCL patient who presented with recurrent fever episodes, pancytopenia, and mediastinal lymphadenopathy. A treatment decision against purine analogs and for rituximab mono was made as lymph node tissue revealed disseminated Mycobacterium kansasii infection. Together with specific antimycobacterial treatment, rituximab mono led to complete hematologic remission after 6 months without aggravating the accompanying infection.

CONCLUSION

Here, we demonstrate successful treatment of HCL with rituximab in a patient with concomitant disseminated M. kansasii infection.

[Hairy cell leukemia: What are the best treatment options for relapsed or refractory patients?]

Hairy cell leukemia is a rare form of leukemia: three hundred new cases are diagnosed each year in France. The diagnosis is based on: (1) morphological examination of the blood and bone marrow smear, (2) analysis by flow cytometry of hairy cells, which express three or the four following markers: CD11c, CD25, CD103 and CD123, (3) identification of the BRAF^V600E mutation, a true molecular marker of the disease. The management of treatment has evolved considerably in recent years. As of today, the purine analogues remain the standard treatment in the first line. Relapses are however observed in about 40% of cases. In the event of a first relapse, the preferred option is treatment with immunochemotherapy i.e. a combination of cladribine plus rituximab. Subsequent relapses are treated with moxetumomab pasudotox or BRAF inhibitors which provide indisputable benefits if third-line treatment is required. We will discuss in patients with relapsed/refractory hairy cell leukemia the needs for personalized medicine and the advantages and disadvantages of each treatment modality. The good prognosis for LT requires treatments that are not immunosuppressive, non-myelotoxic, and do not increase the risk of secondary cancers.

Inhibitor of BRAFV600E Mutation as a Treatment Option for Hairy Cell Leukemia With Deep Neutropenia and Infectious Complications

Standard therapy in hairy cell leukemia (HCL) is often impossible at the time of deep neutropenia/agranulocytosis with or without infectious complications; it is thus a complex therapeutic problem. Vemurafenib has been used to treat resistant HCL since 2012. Because vemurafenib does not have a myelotoxic effect, we thought that it could be used to treat HCL associated with deep neutropenia/agranulocytosis with or without the development of infectious complications as a preliminary stage before treatment with cladribine. We conducted a retrospective analysis of treatment with vemurafenib followed by a standard course of cladribine provided to 22 patients with deep neutropenia/agranulocytosis with or without infectious complications at diagnosis. Vemurafenib was provided to 22 patients with HCL. The response to therapy was evaluated by complete blood cell count (absolute neutrophil count [ANC], hemoglobin concentration, platelet count, absence of hairy cells), spleen size (assessed by ultrasound), and reduce infectious complications. After that, a standard course of cladribine was provided. Among the 22 patients, the male/female sex ratio was 2:1, and median (range) age was 52 (24-78) years. There were 7 patients with severe infectious manifestations admitted to the intensive care unit, including 1 patient during extracorporeal membrane oxygenation. The median (range) ANC at diagnosis was 0.3 (0.04-0.7) × 10⁹/L. Vemurafenib was provided at a dosage of 240 mg 1 or 2 times a day. In 20 patients, vemurafenib was provided for 3 months or more. In 1 case, the effect was not obtained during 1 month of treatment, and the patient died from severe infectious complications during prolonged agranulocytosis. In 21 patients treated with vemurafenib, an increase of ANC was observed and the infectious complications resolved, thus allowing the application of cladribine therapy. After a standard course (0.1 mg/kg per day for 7 days) of cladribine chemotherapy, 18 patients (90%) experienced complete clinical remission and 2 patients (10%) experienced partial remission with residual splenomegaly. In 1 patient, vemurafenib therapy was still ongoing 2 months after initiating therapy. In cases of proven BRAF^V600E mutation, vemurafenib can be successfully used as an effective preliminary therapy in patients with deep neutropenia/agranulocytosis with or without infectious complications before standard therapy with purine analogs.

[Successful surgical resection of rectal cancer in a patient with relapsed hairy cell leukemia under interferon-α treatment]

An 83-year-old man was diagnosed with hairy cell leukemia (HCL). He was treated with cladribine and achieved partial remission. However, pancytopenia due to HCL bone marrow involvement progressed slowly. Nine years later, he developed rectal cancer. Prior to the surgery, endoscopy-assisted submucosal ink injection was performed to identify the area of lower intestinal lesions. The following day, he developed septic peritonitis with shock status, perhaps due to his neutropenia and ink injection procedures. Surgical resection of the cancer was presumed unfeasible; therefore, radiation was performed. Several months later, bone marrow examination revealed HCL infiltration with reticulin fibrosis. Chemotherapy regimens with purine nucleoside analogs, which are the standard treatments for HCL, might accentuate the progression of his rectal cancer and enhance the development of severe infections. Therefore, interferon (IFN) -α was administered as an alternative therapy. Three months later, pancytopenia resolved, and bone marrow examination revealed a remarkable improvement in HCL infiltration and marrow fibrosis. With IFN-α therapy, the patient successfully underwent surgical resection of the rectal cancer. Using INF-α, a prompt recovery from pancytopenia might be expected even in a patient with advanced HCL, who requires surgical treatment for a concomitant cancer.

First report of the unique expression of RECAF (receptor for alfa feto-protein) in adult B-NHL/CLL patients

Background

Lymphoproliferative disorders (LPDs) are a heterogeneous group of diseases characterized by an uncontrolled production of monoclonal lymphocytes. RECAF is the receptor for alpha-fetoprotein, which is re-expressed on malignant cells, thus serving as a broad-spectrum tumor marker.

Methods

The current study is a retrospective study carried out on 200 archival bone marrow trephine biopsy specimens [60 normal control (NC), 38 pathological control (PC) and 102 lymphoproliferative diseases (LPD) specimens]. RECAF expression was assessed using immunohistochemistry.

Results

The percentage of cells that are positive for RECAF was significantly higher in the LPD group than in the NC group (P=0.007), while there was no significant difference between non-Hodgkin lymphoma (NHL) patients and PC regarding the number of RECAF positive cells (P=0.1). RECAF showed a unique expression pattern among the different subtypes of LPD. None of the hairy cell leukemia (HCL) expressed RECAF, while the highest percentage was seen in follicular lymphoma (FL) and diffuse large B cell lymphoma (DLBCL) (P=0.001). Compared to routine histopathology, RECAF was more sensitive in detecting bone marrow (BM) infiltration in FL, mantle cell lymphoma (MCL), and DLBCL (P=0.01).

Conclusion

RECAF is significantly expressed in the BM of NHL/chronic lymphocytic leukemia (CLL) patients. RECAF shows a unique expression pattern among the different subtypes of LPD. Furthermore, RECAF may help to detect bone marrow infiltration in lymphoma cells. This may help in the diagnosis, follow-up, and targeting of LPD.

A Rare Case of Hairy Cell Leukemia with Unusual Loss of CD123 Associated with COVID-19 at the Time of Presentation

Coronavirus disease 2019 (COVID-19) pandemic has been a serious threat and has been reported with different presentations and complications. Older age, along with comorbidities such as diabetes, hypertension, or cardiac disease, increases the risk factors for COVID-19 severity and death [N Engl J Med. 2020;382(18):1708–20 and Lancet Respir Med. 2020 05;8(5):475–81]. It is proposed that cancer patients have a significantly higher incidence of severe incidents including admission to the intensive care unit, the necessity for assisted ventilation, and even death after catching the virus compared with non-cancer patients [Lancet Oncol. 2020;21(3):335–7]. It is also described that cancer patients appear to be twice as likely to contract infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) [JAMA Oncol. 2020;6(7):1108–10]. Hairy cell leukemia (HCL) is a rare B-cell lymphoproliferative disorder, with patients typically presenting with cytopenias, marked splenomegaly in 80–90% of patients, circulating leukemia cells, bone marrow infiltration and the presence of BRAF V600E somatic mutation [Indian J Hematol Blood Transfus. 2014;30(Suppl 1):413–7]. Leukemic cells classically have central nuclei and abundant cytoplasm with hairy-like projections and express CD11c, CD25, CD103, and CD123 [Indian J Hematol Blood Transfus. 2014;30(Suppl 1):413–7]. Loss of CD123 in HCL has been rarely reported in the literature [Am J Hematol. 2019;94(12):1413–22]. We describe a unique case of a COVID-19-positive male who presented with severe respiratory symptoms, deteriorated quickly, and was intubated. Workup of severe progressive pancytopenia and bone marrow examination revealed HCL without splenomegaly and with atypical unusual loss of CD123. To our knowledge, this is the first case of CD123-negative HCL without splenomegaly associated with COVID-19 infection as the initial presentation.

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.

A population-based study of hairy cell leukemia over a period of 20 years

There are limited population-based studies of hairy cell leukemia (HCL), a rare chronic lymphoproliferative disorder of B-cells. We conducted a population-based study that included all patients diagnosed with HCL between 1996 and 2016 in Western Normandy. Recorded data focused on medical history, clinical presentation, biological results, treatment modalities in the first line and in relapsed/refractory patients and the occurrence of secondary malignancies. One hundred and twenty-three HCL patients were registered in the database. HCL represented 0.7% of all malignant hematological disorders and 3.0% of all leukemia. The overall age-standardized incidence ratio (SIR) was 0.39/100,000 inhabitants in men and 0.09/100,000 in women, and it remained stable over the 20-year period analyzed. One hundred and seven patients (88%) received first-line treatment, 33 patients (27%) received at least 2 lines of treatment and 14 patients (11%) received more than 2 lines. Cladribine used as first-line treatment induced a high hematological complete response (HCR) rate of 92%. The median overall survival (OS) was over 15 years, with 5-year and 10-year survival rates of 84% and 70.5%. No significant differences in OS were observed between men and women, between the calendar periods studied or between patients who received a single line treatment with IFN-α or PNA. The risk of relapse was higher with IFN-α treatment, requiring subsequent treatments in that patients. The time to next treatment (TTN) tends to be longer for PNAs compared to IFN-α even if difference is not significant. Secondary cancers were observed in 9/123 patients (7.3%) with solid tumors in 8 patients and hematological malignancy in one patient. Our data confirm in real life that single courses of cladribine administered to patients with HCL induce high response rates, the majority of which are HCR. Relapses seem less frequent than with IFN-α and the administration schedule is less restrictive for the patients. The emergence of chemo-immunotherapy and the development of effective new drugs such as recombinant immunotoxins and BRAF targeting will offer new possibilities in the management of HCL patients.

Concurrent chronic lymphocytic leukemia/small lymphocytic lymphoma and hairy cell leukemia: clinical, pathologic and molecular features

Simultaneous occurrence of hairy cell leukemia (HCL) and chronic lymphocytic leukemia/small lymphocytic lymphoma (termed CLL) is very rare. Clinical characteristics, pathology and management of these cases have not been well described. We present six patients with CLL and HCL or HCL variant (HCL-v). Of six patients, three were initially diagnosed with CLL and later developed concurrent HCL. Two patients had concurrent HCL or HCL-v and CLL at initial diagnosis. One had HCL first, followed by concurrent CLL. Polymerase chain reaction analysis demonstrated B-cell clonality in all cases, with two distinct clonal populations in four cases, and three clonal populations in one case. Five patients were treated with a combination of a purine analog such as fludarabine, cladribine, and pentostastin with either rituximab or ibrutinib, while one received dabrefenib and trametinib. All patients achieved a durable response to either CLL or HCL-directed therapy with reduction or ablation of coexisting B-cell clones.

BRAF V600E mutation detection in hairy cell leukemia-utility of archival DNA from bone marrow aspirate/imprint smear and amplification refractory mutation system

BRAF V600E is a disease defining mutation for hairy cell leukemia (HCL), which helps in its diagnosis and differentiation from morphologically similar splenic marginal zone lymphoma (SMZL) and HCL-variant (HCL-v). Forty eight cases:HCL(n = 34), SMZL(n = 11) and HCL-v(n = 3) were included. Of these, 32 were retrospective and 16 were prospective. DNA was extracted, in retrospective cases from cells obtained by smears from bone marrow aspirate/trephine imprint (BMA/BMTx) slides, and in prospective cases from peripheral blood (PB)/BMA samples. BRAF V600E mutation testing was done using ARMS-PCR. BRAF V600E mutation was positive in all HCL and negative in all SMZL and HCL-v cases. DNA extracted from BMA/BMTx slides gave results comparable to DNA extracted from PB/BMA samples. Median age of presentation for HCL (53 years) and SMZL (56 years) were quite similar, however, HCL-v (71 years) cases presented at an older age. Statistically significant differences between the three groups were seen for total leucocyte, platelet, absolute lymphocyte and monocyte counts, bone marrow-infiltration pattern, reticulin fibrosis, and an expression of CD11c, CD25, CD103, CD123, and CD200. The use of BMA/BMTx smears for DNA extraction was found to be a useful alternative to DNA extraction from formalin-fixed paraffin-embedded biopsy sections. ARMS-PCR is an efficient and specific technique to detect BRAF V600E mutation in HCL patients.

"Hairy Cell Leukemia (HCL): 'Real World' Outcome"

HCL is an uncommon B cell lympho-proliferative disorder with high remission rates. There is paucity of data on the long-term outcome of HCL from India. We retrospectively collected data from individual case records of patients with HCL who were treated in Cancer Institute, Chennai from January 2001 until January 2018. Sixteen patients were diagnosed with HCL and were treated with cladribine (81%), interferon (13%) and one patient received only best supportive care (6%). All the treated patients achieved complete response. More than half of the patients developed febrile neutropenia but there were no treatment related mortality. The 5-year DFS was 77% and 5-year OS was 80%. Relapse of disease was seen in 27%. HCL is a curable malignancy with high remission rates and survival comparable to patient treated in west.

Biology and Treatment of Hairy Cell Leukemia

OPINION STATEMENT

Despite its rarity, hairy cell leukemia (HCL) remains a fascinating disease and the physiopathology is becoming more and more understood. The accurate diagnosis of HCL relies on the recognition of hairy cells by morphology and flow cytometry (FCM) in the blood and/or bone marrow (BM). The BRAF V600E mutation, an HCL-defining mutation, represents a novel diagnostic parameter and a potential therapeutic target. The precise cellular origin of HCL is a late-activated postgerminal center memory B cell. BRAF mutations were detected in hematopoietic stem cells (HSCs) of patients with HCL, suggesting that this is an early HCL-defining event. Watch-and-wait strategy is necessary in approximately 10% of asymptomatic HCL patients, sometimes for several years. Purine analogs (PNAs) are the established first-line options for symptomatic HCL patients. In second-line treatment, chemoimmunotherapy combining PNA plus rituximab should be considered in high-risk HCL patients. The three options for relapsed/refractory HCL patients include recombinant immunoconjugates targeting CD22, BRAF inhibitors, and BCR inhibitors. The clinical interest to investigate blood minimal residual disease (MRD) was recently demonstrated, with a high risk of relapse in patients with positive testing for MRD and a low risk in patients with negative testing. However, efforts must be made to standardize MRD analyses in the near future. Patients with HCL are at risk of second malignancies. The increased risk could be related to the disease and/or the treatment, and the respective role of PNAs in the development of secondary malignancies remains a topic of debate.

Adverse event rates and economic burden associated with purine nucleoside analogs in patients with hairy cell leukemia: a US population-retrospective claims analysis

Background

Purine nucleoside analogs (PNAs) are the recommended first-line treatment for patients with hairy cell leukemia (HCL), but they are associated with adverse events (AEs). Due to a lack of real-world evidence regarding AEs that are associated with PNAs, we used commercial data to assess AE rates, AE-related health care resource utilization (HCRU), and costs among PNA-treated patients with HCL. Adults aged ≥18 years with ≥2 claims for HCL ≥30 days apart from 1 January 2006 through 31 December 2015 were included. Included patients had ≥1 claim for HCL therapy (cladribine ± rituximab or pentostatin ± rituximab [index date: first claim date]) and continuous enrollment for a ≥ 6-month baseline and ≥ 12-month follow-up period. Patient sub-cohorts were based on the occurrence of myelosuppression and opportunistic infections (OIs). Generalized linear models were used to compare HCRU and costs.

Results

In total, 647 PNA-treated patients were identified (mean age: 57.1 years). Myelosuppression and OI incidence were 461 and 42 per 1000 patient-years, respectively. Adjusted results indicated that those with myelosuppression had higher rates of hospitalization (47.4% vs 12.4%; P < .0001) and incurred higher mean inpatient costs ($23,517 vs $12,729; P = .011) and total costs ($57,325 vs $34,733; P = .001) as compared with those without myelosuppression. Similarly, patients with OIs had higher rates of hospitalization (53.8% vs 30.8%; P = .025) and incurred higher mean inpatient costs ($21,494 vs $11,229; P < .0001) as compared with those without OIs.

Conclusions

PNA therapy is highly effective but associated with significant toxicities that increase costs; these findings indicate a need for therapies with improved toxicity profiles and better risk stratification of patients at risk of developing myelosuppression and OIs.

Usefulness of Dual Immunohistochemistry Staining in Detection of Hairy Cell Leukemia in Bone Marrow

OBJECTIVES

We evaluated efficacy of two dual immunohistochemistry (IHC) staining assays in assessing hairy cell leukemia (HCL) involvement in core biopsies and compared the results with concurrently collected flow cytometric data.

METHODS

Overall, 148 patients with HCL (123 male, 25 female; mean age: 59.8 years; range: 25-81 years) had multiparameter flow cytometry performed using CD19, CD20, CD22, CD11c, CD25, CD103, CD123, surface light chains, CD5, and CD23. In parallel, bone marrow IHC was done using PAX5/CD103 and PAX5/tartrate-resistant alkaline phosphatase (TRAP) dual IHC stains.

RESULTS

Overall sensitivity of dual IHC stains was 81.4%, positive predictive value was 100%, and negative predictive value was 81.7%. All IHC-positive cases concurred with flow cytometry data, even when HCL burden was extremely low in the flow cytometry specimens (as low as 0.02% of all lymphoid cells).

CONCLUSIONS

Dual IHC stain is a sensitive tool in detecting HCL, even in cases with minimal disease involvement.

Concomitant BRAF Mutation in Hairy Cell Leukemia and Papillary Thyroid Cancer: Case Report

Hairy cell leukemia (HCL) is rare type of leukemia. This neoplasm is well-known to present with pancytopenia and splenomegaly. HCL is associated with BRAF mutation in 100% of cases. It is also associated with hematological and oncological malignancies such as melanoma and papillary thyroid cancer. Although the association of both cancers (HCL and papillary thyroid cancer) with BRAF mutation is well established in the literature, as far as we know it has not been reported before in the same patient. Here we report 48-year-old male diagnosed with HCL and papillary thyroid cancer and who is BRAF positive in both diagnostic tissues.

Retrospective Analysis of Hairy Cell Leukemia Patients Treated with Different Modalities as First Line: Real-Life Experience Over 20 years

We aimed to analyze the characteristics and response rates of different treatment modalities in hairy cell leukemia patients over 20 diagnosed as hairy cell leukemia (HCL). Clinical data, response rates and survival outcome of the patients who were diagnosed with HCL were retrospectively analyzed. Fifty-two patients with a median age of 50 (28-87) years were enrolled in the study. 38 patients (73%) were male and male to female ratio was 2.7. First line therapy was cladrabine in 36 patients (69.2%). The overall response rate was 97%. CR and PR rates were 86.1% and 11.1%, respectively. Interferon was used in 10(19.2%) patients who were diagnosed before 2000s years. CR and PR rates were 70% and 30%, respectively. Although the CR rates were lower in IFN group, this difference could not be reached statistically significance (p = 0.24). The median follow up was 48 months (12-252). The median OS was not reached and median PFS was 150 months (95% CI, 116-214). The OS at 36 and 48 months were 95.9% and 92.3%, respectively and the PFS at 36 and 48 months were 90.2% and 83.4%, respectively. After the introduction of purine analogues, the fate of the HCL patients have been changed. Cladrabin achieved very high response rates in both young and older patients, in our study. Although relapse still constitutes a problem, another single dose of cladrabine results in good response rates.

[Bronchoalveolar lavage in hairy cell leukemia with pulmonary infiltration]

We report a 78-year-old male patient suffering from hairy cell leukemia, presenting clinically mainly with dyspnea. Radiology exhibited bilateral ground-glass shadows. In order to prevent pneumonia as a possible side effect due to conventional chemotherapy, it was decided to first treat the patient with rituximab; however, dyspnea persisted. Therefore, bronchoscopy was performed and specimens were sampled for both histological examination and bronchoalveolar lavage (BAL) analysis. BAL showed lymphocytosis (28.7%), and by means of immunocytochemistry a few CD79a+ B‑lymphocytes as well as lymphoid cells positive for the hairy cell marker DBA44 were observed. In addition, molecular study revealed the BRAF V600E mutation. Thus, the findings of BAL were interpreted as lung infiltration by hairy cell leukemia. This result was confirmed by histology. Following a therapy switch to cladribine, a significant improvement was reached. Pulmonary infiltrates by hairy cell leukemia were rarely described. This case represents the first report of hairy cell leukemia diagnosed by means of BAL. It may be difficult to clearly separate between lymphoma infiltration of the lung and medicamentous pneumonitis, but this differential diagnosis can be supported by morphological methods.

Prognostic significance of Fc receptor-like 1 in patients with chronic lymphocytic leukemia, hairy cell leukemia, and various B-cell non-Hodgkin's lymphoma

Fc receptor-like 1 (FCRL1) positively regulates B-cell responses and may involve in the pathogenesis of B-cell malignancies. This study examined the expression pattern of FCRL1 in B-cell non-Hodgkin's lymphoma patients using real-time PCR and flow cytometry. The results revealed higher levels of FCRL1 expression in diffuse large B-cell lymphoma, hairy cell leukemia, and Burkitt lymphoma patients compared with control groups. There was a significant reduction in the levels of FCRL1 expression in chronic lymphocytic leukemia and mantle cell lymphoma patients compared with healthy individuals. These findings suggest FCRL1 as an excellent marker for the prognosis or immunotherapy of B-cell malignancies.

Moxetumomab pasudotox for the treatment of relapsed and/or refractory hairy cell leukemia

Introduction: Hairy cell leukemia is a rare indolent B-cell malignancy, characterized by pancytopenia, recurrent infections, and splenomegaly. After initial therapy with purine nucleoside analogs, up to 50% of patients relapse after several years of remission. The number of relapsed patients is increasing and, until recently, there was no approved therapy with durable responses for hairy cell leukemia patients in the relapsed setting, thus the need for new non-chemotherapy approach with significant efficacy and less myelosuppression. Areas covered: Moxetumomab pasudotox is a recombinant immunotoxin containing a Fv fragment of an anti-CD22 monoclonal antibody and truncated Pseudomonas exotoxin (PE38). The authors reviewed pre-clinical and clinical studies that led to the FDA approval of the drug in patients with relapsed and/or refractory hairy cell leukemia, who received at least two prior therapies, including at least one purine nucleoside analog. Expert opinion: Moxetumomab pasudotox demonstrated a durable complete remission rate of 30% in heavily pretreated patients with hairy cell leukemia, and MRD eradication in 85% of responding patients. Moxetumomab pasudotox got a global FDA approval in September 2018. The US prescribing information carries boxed warnings regarding the risk of capillary leak syndrome and hemolytic uremic syndrome. Long-term follow-up of the pivotal study is ongoing (NCT01829711).

[Hairy cell leukemia complicated by bone marrow necrosis following cladribine administration]

Classic hairy cell leukemia (classic HCL) is a rare disease associated with indolent mature B-cell lymphoma. A 50-year-old man presented with pancytopenia for 3 years and was diagnosed with classic HCL because his lymphoid cells showed a hairy morphology with oval nuclei and indistinct nucleoli both in the peripheral blood and bone marrow (BM) smears. Flow cytometric analysis revealed that these cells expressed CD11c, CD25, and CD103, and the Sanger sequence method detected BRAF V600E mutation. Cladribine (0.09 mg/kg/day) was initiated for 7 days via continuous intravenous injection. On day 13, the patient died from bloodstream infection caused by methicillin-resistant Staphylococcus epidermidis. Autopsy findings revealed BM necrosis without residual leukemia cells caused by classic HCL, severe infection, and agents, such as cladribine and granulocyte-colony stimulating factor; however, its cause remained undetermined. Both early diagnosis and immediate clinical intervention are required to improve the clinical outcomes in classic HCL. The cause of hematopoiesis disturbance should also be identified using BM biopsy or magnetic resonance imaging before initiating treatment in classic HCL with severe pancytopenia.

Acute profound sensorineural hearing loss as the initial manifestation of Hairy Cell Leukemia, Case Report and literature review

INTRODUCTION

Hematologic diseases are rarely present with sudden hearing loss as an initial symptom. Although the precise cause of sudden sensorineural hearing loss has not been identified, several pathophysiological mechanisms have been proposed. However, a variety of hematologic diseases are among the causes of sudden onset deafness. This article represents the first reported case of Hairy cell leukemia (HCL) which presented with acute unilateral profound sensorineural hearing loss as an inital mainfestation.

PRESENTATION OF CASE

A 41-year-old man presented with unilateral sudden hearing loss for one day's duration was found to have HCL during a worked up for his hearing loss. The disease worsened, and there was no improvement in his hearing.

DISCUSSION

Sudden sensorineural hearing loss can rarely be seen as a paraneoplastic occurrence.Very few cases have been reported in the literature. It has been reported as a presenting symptom of leukemia in numerous clinical and histopathological reports concerning the hearing loss in hematologic diseases. Our case is an example of such a rare incidence.

CONCLUSION

The purpose of this study is to draw physicians' attention to the possible association between acute sensorineural hearing loss to HCL, and to highlights permanent deafness as a complication secondary to HCL. Furthermore, it is important to increase awareness on early diagnosis and treatment that may improve treatment outcomes.

High prevalence of antibiotic allergies in cladribine-treated patients with hairy cell leukemia - lessons for immunopathogenesis and prescribing

The relationship between hematological malignancy and chemotherapy on the prevalence of antibiotic allergy label (AAL) is ill-defined. We performed a multicenter retrospective case-control study comparing AAL rates among cladribine-treated hairy cell leukemia (C-HCL) cases, non-HCL cladribine-treated controls (control-1), and fludarabine-treated controls (control-2). The prevalence of AALs in C-HCL patients was 60%, compared with control-1 (14%, p < .01) and control-2 patients (25%, p < .01). The predominant phenotype was maculopapular exanthem (92%). The drugs implicated in AAL causality in C-HCL patients included beta-lactams (81%), trimethoprim-sulfamethoxazole (58%), and allopurinol (69%). C-HCL patients demonstrate high rates of AAL, potentially due to immune dysregulation, impacting beta-lactam utilization.

Outcomes and second neoplasms in hairy cell leukemia: A retrospective cohort

Hairy cell leukemia (HCL) is a rare chronic B-cell lymphoproliferative disease which is treated on the basis of small studies, making the literature still scarce of reports, especially of those conducted in Latin America. Here we intend to describe clinical characteristics, rates of response, survival and second neoplasms in HCL patients treated in a reference center in Brazil. All patients diagnosed with HCL between July/1987 and Jun/2018 were included in this analysis. Fifty-four patients were included in this analysis. Median age at diagnosis was 55 years (range, 26-88), with 37% being above 60 years-old. Most patients were treated with cladribine in our cohort (n = 36; 68%), administered through intravenous continuous infusion. Remaining patients were firstly managed with splenectomy (n = 7; 13%), IFN (n = 6; 11%) and rituximab (n = 2; 4%). In a univariate analysis, platelet count and B2M level at diagnosis were statistically associated with CR achievement (p = 0.004 and p = 0.024, respectively). A median follow-up time of 9 years was calculated. Estimated 10-year overall survival was 91.1% (95% confidence interval, 77-97). In this cohort, 10 patients had any second neoplasm, diagnosed before or after HCL. Regarding the sites of cancer, 69% were of skin - 8/16 carcinoma-type and 3/16 melanoma-type. Our response and survival data are similar to those reported by literature, which reaffirms the role of purine analogs in current HCL management. With a very long follow-up we also have observed a high incidence of second neoplasm.

Primary peg-filgrastim prophylaxis versus filgrastim given "on demand" for neutropenia during therapy with cladribine for hairy cell leukemia

BACKGROUND

Major advances in the treatment of patients with hairy cell leukemia (HCL) have been made following the introduction of purine analogues. The major significant short-term toxicity of cladribine therapy are neutropenia and neutropenic fever (NF) which may be life-threatening.

AIM

In this retrospective study, we compared the incidence and duration of neutropenia and hospitalization in patients with HCL treated with cladribine followed by peg-filgrastim as primary prophylaxis versus daily filgrastim given "on demand" according to absolute neutrophil count (ANC).

METHODS

Medical records of patients with HCL diagnosed and followed in 12 medical centers in Israel during 1985-2015 were examined for details of disease at diagnosis. The efficacy of peg-filgrastim and filgrastim was assessed by evaluating the incidence of neutropenia (ANC < 1.0 × 10 [9]/L), number and length of hospitalizations, and number of days from the last day of therapy to recovery of ANC to >1.0 × 10 [9]/L.

RESULTS

The study population included 202 patients with HCL, 159 of whom (80.7%) were treated with cladribine; 78 patients (49%) required hospitalization for the administration of broad-spectrum antibiotics due to NF. Twenty-eight (19%) patients were treated with peg-filgrastim as primary prophylaxis, while 74 (64%) received filgrastim "on demand" due to neutropenia. Median length of hospitalization, and nadir duration were 8 and 18 days respectively (p = 0.71, p = 0.44).

CONCLUSIONS

Infectious complications post-cladribine treatment remain high. No difference was found in terms of incidence of NF, number of febrile days, and nadir duration in patients receiving primary peg-filgrastim prophylaxis compared to filgrastim given on demand. Both approaches are justifiable, and the choice remains at the physician's discretion.

Moxetumomab pasudotox-tdfk for relapsed/refractory hairy cell leukemia: a review of clinical considerations

PURPOSE

Hairy cell leukemia (HCL) is a rare mature B cell leukemia. Purine analogs are the mainstay of treatment of HCL, but relapse after purine analog therapy is common. Outcomes of treatment of relapsed/refractory HCL typically diminish with each successive line of therapy. Moxetumomab pasudotox-tdfk is a novel recombinant immunotoxin approved for the treatment of patients with relapsed/refractory HCL who have received at least two prior therapies, including a purine analog. This article reviews HCL treatment, focusing on moxetumomab pasudotox-tdfk, its place in therapy, considerations for preparation and administration, and strategies for prevention and management of toxicities.

METHODS

A literature search was conducted in the PubMed database from inception to January 2019, using the following terms: moxetumomab, hairy cell leukemia, relapsed/refractory hairy cell leukemia, immunotoxin, and CD22. The package insert and available posters and abstracts were also reviewed.

RESULTS

FDA approval of moxetumomab pasudotox-tdfk was based on a phase III single-arm, open-label trial in 80 patients. Treatment with moxetumomab pasudotox-tdfk yielded a durable complete response rate of 30% with a median duration of response that had not yet been reached at a median follow-up of 16.7 months. The objective response rate was 75% based on blinded independent central review. The most common adverse reactions were infusion-related reactions, edema, nausea, fatigue, headache, pyrexia and anemia. Serious adverse events include capillary leak syndrome and hemolytic uremic syndrome.

CONCLUSIONS

Clinicians providing care for patients receiving moxetumomab pasudotox-tdfk should be aware of the strategies required for safe administration, including the management of serious adverse events.