Treatment Of Hairy Cell Leukemia Research Articles

First Line Chemo-Free Therapy with the BRAF Inhibitor Vemurafenib Combined with Obinutuzumab Is Effective in Patients with Hcl

First Line Chemo-Free Therapy with the BRAF Inhibitor Vemurafenib Combined with Obinutuzumab Is Effective in Patients with Hcl

The treatment of hairy cell leukemia with a focus on long lasting responses to cladribine: A 30-year experience.

The treatment of hairy cell leukemia (HCL) has considerably changed over years. Purine analogues, namely cladribine, now represent the treatment of choice. One hundred and eighty-four patients were followed between 1986 and 2018 and treated according to era-specific guidelines. Responses were classified by combining Consensus Resolution criteria and marrow immunohistochemistry. Patients were grouped according to the number of treatment lines they received. Patients treated first line responded in 86% of cases, with complete response (CR) in 44% of cases. Response rates remained high throughout the first four lines (84%, 81%, 79% for the second line onward, with CR in 38%, 37%, 15% of cases respectively). One hundred and twenty-two patients received cladribine as first line treatment, with a response rate of 86% and a CR rate of 54%. Among the 66 CR patients, 45 (68%) have never received further therapy: 11 patients are in continuous CR between 5 and 10 years after treatment, 14 between 10 and 20 years and three patients at more than 20 years. Median time-to-next treatment (TTNT) for frontline cladribine-treated patients was 8.2 years: partial responders had a significantly shorter median TTNT than CR patients (5.3 years vs median not reached at 25.8 years, p< 0.001). Patients with HCL require subsequent lines of therapy in more than 50% of cases. Purine analogues allow significant response rates when applied first line and upon retreatment. Some patients may enjoy long lasting treatment-free intervals after one course of cladribine.

Hairy cell leukemia: a brief update on current knowledge and treatment prospects.

This article provides a brief update on the recommended diagnosis and treatment strategies for patients with the classic form of hairy cell leukemia (HCL) and HCL variant (HCLv). HCL is a chronic B-cell malignancy with multiple treatment options. In recent years, many novel drugs have been assessed for HCL treatment with promising results. The investigated nonchemotherapy options include moxetumomab pasudotox, which targets CD22; vemurafenib or dabrafenib, which target the BRAFV600E protein; trametinib, which targets mitogen-activated protein kinase enzyme; and ibrutinib, which targets Bruton tyrosine kinase. Purine analogs significantly improve survival in patients with HCL. However, patients often relapse, require multiple treatments, and may become refractory. The introduction of novel agents has expanded the spectrum of therapy possibilities in those patients. In the coming years, they will assist standard therapy for patients with HCL who may currently have suboptimal results.

Dabrafenib Is a Safe and Effective Therapy in Relapsed/Refractory Classical Hairy Cell Leukemia

BACKGROUND: Hairy cell leukemia (HCL) is a rare indolent B-cell lymphoproliferative disorder. The BRAF V600E mutation was shown to be the underlying genetic driver for the vast majority of classical HCL (HCLc) cases and treatment with the BRAF inhibitor (BRAFi), vemurafenib, has proven extremely successful. Dabrafenib is an oral BRAFi used in melanoma, often in conjunction with trametinib, a MEK inhibitor. Data exists on the use of dabrafenib combined with trametinib in HCLc but there is no efficacy or safety data on either single agent dabrafenib or dabrafenib combined with rituximab. We present a small series of 7 patients treated with either single agent dabrafenib or combination dabrafenib and rituximab. METHODS: Since 2018 dabrafenib was accessible via a Novartis managed access programme for BRAF V600E mutated HCLc patients who had no alternative treatment options. Six patients received dabrafenib, 2 as single agent due to recent prior ineffective rituximab therapy or severe rituximab infusion reaction and the remaining 4 patients with dabrafenib and rituximab. Dabrafenib was given at 150mg twice daily on a continuous 28 day cycle. Rituximab 375mg/m2 IV was given once every 2 weeks for a total of 8 doses. As there was no availability for re-treatment on cessation of therapy and no other suitable/accessible treatment options, patients with ongoing response and good tolerance were continued on indefinite therapy. One additional patient was treated with frontline dabrafenib and rituximab due to various comorbidities including end stage renal failure limiting other treatment options. RESULTS: Mean age on commencing dabrafenib was 73 (52-87) and in the relapsed patients the median number of prior lines of therapy was 5 (3-13). Four patients had undergone prior splenectomy. Two patients had received prior BRAFi therapy with vemurafenib and 3 had received prior Moxetumomab. Patients received a median of 8 cycles of dabrafenib. 4 patients received all 8 cycles of rituximab with 1 discontinuing rituximab due to adverse drug reaction. Adverse drug reactions to dabrafenib were mostly grade 1-2. The most common reaction was benign keratotic skin lesions occurring in 5/7 patients. Their onset was typically after 4 weeks of treatment, persisting whilst therapy continued. Other notable adverse drug reactions were hair thinning and palmar-plantar erythrodysesthesia both occurring in 3/7 patients. Hair thinning did seem to improve with decreasing the dosage and resolve on cessation of the drug. Palmar-plantar erythrodysesthesia was managed with dose reduction and non-steroidal anti-inflammatory drugs. Response assessment criteria used were from the 2017 hairy cell leukemia foundation consensus guidelines for the diagnosis and management of patients with HCLc. All patients responded to therapy. Hematological response was rapid, most patients achieving hematological CR after 2-3 cycles. Five patients achieved a CR, 2 were MRD+ve, 2 were MRD-ve and 1 was a radiological CR. The remaining 2 patients achieved a hematological response, 1 partial and 1 complete. Six patients had sufficient follow up for assessment with 2/6 having relapsed and 4/6 remaining in remission. Median follow up was 17 months, median DOR and median OS were not reached. The 2 patients in our cohort (patients 1 and 3) receiving prior vemurafenib each received 6 cycles, 1 achieving CR lasting 3 months, the other achieving PR lasting 11 months. Both responded rapidly to dabrafenib, one treated with dabrafenib and rituximab achieved an MRD+ve CR with DOR 21 months. The other received single agent dabrafenib and achieved a hematological response with DOR 15.2 months. Treatment response and survival are shown in table 1 and figure 1. Figures 2-7 show the hematological response at time points within the first year of therapy. DISCUSSION: In this small cohort we have shown that dabrafenib as a single agent or combined with rituximab is a safe and effective therapy in BRAF V600E mutated HCLc, even in those patients with prior time limited duration BRAFi therapy. There was no hematological toxicity noted. The main adverse drug effect was development of skin lesions however none were malignant. The only malignant lesion noted pre dated the commencement of dabrafenib. Dermatological surveillance is therefore recommended. Hematological response was rapid with significant improvement seen as early as 4 weeks from commencing therapy. Disclosures El-Sharkawi: Janssen:Honoraria, Membership on an entity's Board of Directors or advisory committees;Roche:Other: Conference fees. OffLabel Disclosure: Use of BRAF inhibitor Dabrafenib in BRAF V600E mutation positive classical Hairy Cell Leukemia.

CLL-358: First-Line Treatment of Hairy Cell Leukemia with Cladribine Followed by Rituximab Consolidation Significantly Improves Leukemia-Free Survival

Context Purine analogue therapy remains the standard of care in hairy cell leukemia (HCL) management. Despite high remission rates, many patients subsequently relapse and require re-treatments. Objective The aim of this study is to compare the effectiveness and safety of cladribine vs. cladribine followed by rituximab consolidation as first-line therapy of HCL. Design This is a retrospective study including all consecutive patients with classical HCL treated and followed at the American University of Beirut Medical Center (AUBMC) between 2000 and 2019. Methods We identified 29 HCL patients, with a median age of 50.5 (range: 30–71) years. Patients were divided into two cohorts based on treatment received: cohort A (N=14) received cladribine 5.6 mg/m2 intravenously (IV) for 7 days as a single agent, and cohort B (N=15) received the same dose of cladribine followed by rituximab 375 mg/m2 IV weekly for eight doses. Rituximab consolidation was given after a median time of 33 days (17–60 days) from cladribine completion. Complete remission rates were 64% and 100% in cohorts A and B, respectively. In cohort A, seven (50%) patients relapsed after a median duration of 48 months (range: 1–209 months), requiring second-line treatment with cladribine followed by rituximab. In cohort B, no relapses occurred. After a median follow up of 67 months (range: 1–227 months), the 5-year disease-free survival was significantly better in group B (100%) compared to group A (58%) (HR=0.16, 95% CI: 0.032–0.84, p=0.03). There was no significant difference in overall survival between the two groups. Grade 3/4 adverse events were observed in 92%% and 80% of patients in cohorts A and B, respectively, mainly neutropenia (78.5% vs 66.6%) and febrile neutropenia (71% vs. 40%). One patient in cohort B who received rituximab consolidation too early (day 17) died from febrile neutropenia and septic shock. Conclusion Consolidation rituximab after cladribine in frontline treatment of classical HCL showed high response rate of 100% and translated into a significant improvement in disease-free survival. Cladribine followed by rituximab consolidation may be considered as standard first-line therapy of HCL.

Biotransformation of cladribine by a nanostabilized extremophilic biocatalyst

Cladribine (2-chloro-2′-deoxy-β-d-adenosine) is a 2′-deoxyadenosine analogue, approved by the FDA for the treatment of hairy cell leukemia and more recently has been proved for therapeutic against many autoimmune diseases as multiple sclerosis. The biosynthesis of this compound using Thermomonospora alba CECT 3324 as biocatalyst is herein reported. This thermophilic microorganism was successfully entrapped in polyacrylamide gel supplemented with nanoclays such as bentonite. The immobilized biocatalyst (T. alba-Ac-Bent 1.00 %), was able to biosynthesize cladribine with a conversion of 89 % in 1 h of reaction and retains its activity for more than 270 reuses without significantly activity loss, showing better operational stability and mechanical properties than the natural matrix. A microscale assay using the developed system, could allow the production of at least 181 mg of cladribine in successive bioprocesses.

Biology and Treatment of Hairy Cell Leukemia.

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.

Developing and Evaluating Recombinant Immunotoxins against Latent Epstein Barr Virus Infected Cells

Epstein Barr virus (EBV), commonly associated with acute infectious mononucleosis, is an oncogenic virus implicated in thousands of cancer‐related deaths every year worldwide. Estimates suggest that 90–95% of the population worldwide are infected with EBV. Individuals with healthy immune system can manage acute infections with minimal symptoms, but EBV often persists in a latent state even after the acute infection has cleared. Studies have shown a definitive link between latent EBV infections and the development of certain cancers such as nasopharyngeal cancer and Burkitt’s lymphoma, yet there are currently no targeted treatments against latent EBV induced cancers. A potential treatment for both latent EBV infections and EBV‐induced malignancies is recombinant immunotoxins (RITs) targeted to the virus‐specific membrane protein, LMP1. RITs are fusion proteins comprised of an antibody and protein toxin designed to identify and kill specific populations of cells. RITs using the bacterial toxin Pseudomonas exotoxin A (PE) have been extensively studied. Several RITs are in clinical trials, and one (moxetumomab pasudotox) has received FDA approval for the treatment of Hairy Cell Leukemia. Using a previously developed anti‐LMP1 antibody, we have cloned, expressed, and purified two anti‐LMP1 single‐chain variable fragment antibody joined recombinantly to either PE24 or PE38. We have begun to develop a HEK293 cell line that expresses LMP1 in order to evaluate the cytotoxicity of our anti‐LMP1 RITs. Subsequent experiments will evaluate these RITs as a therapeutic against EBV‐infected cell lines.Support or Funding InformationThis project was support by the Towson University’s Graduate Student Association and the Fisher College of Science and Mathematics

The Treatment of Hairy Cell Leukemia with a Focus on Long Lasting Responders to Cladribine: A Thirty-Year Experience from the Institute of Hematology of Bologna

The treatment of hairy cell leukemia (HCL) has deeply changed over years. Purine analogs, namely cladribine (2CdA) now represent the treatment of choice. The BRAF V600E mutation is now regarded as the pathogenic event. One hundred and eighty-four patients were followed between 1986 and 2018 and treated according to era-specific guidelines. This is the largest monocentric series reported. Responses were classified by combining Consensus Resolution criteria and marrow immunohistochemistry. Patients were grouped according to the number of treatment lines they received (table). Ten patients treated with frontline 2CdA and in complete response (CR) for at least 5 years were tested for the presence of the BRAF V600E mutation in peripheral blood by droplet digital PCR as a molecular marker for active disease. Patients treated first line responded in 86% of cases, with 44% CR. Response rates remained high throughout the first 4 lines (84%, 81%, 79% for the second line onward, with CR in 38%, 37%, 15% of cases respectively), although decreasing progressively with the number of treatments received. One hundred and twenty-two patients received 2CdA as first line treatment, with a response rate of 86% and a CR rate of 54%. Among the 66 CR patients, 45 (68%) have never received further therapy: 11 patients are in continuous CR between 5 and 10 years after treatment, 14 between 10 and 20 years and 3 patients at more than 20 years. Median time-to-next treatment (TTNT) for patients after receiving 2CdA was 8.2 years: partial responders had a significantly shorter median TTNT than CR patients (5.3 years versus median not reached at 25.8 years, p=0.0001) (figure). Seven patients in CR for more than 5 years after front line 2CdA were BRAF V6500E negative in peripheral blood. One of these displayed disease recurrence and required further treatment roughly 2 years later. Three patients were positive for the BRAF V600E mutation at 6.5, 8.4 and 13.7 years after treatment and developed an overt disease relapse between 4 months and 2 years. Patients with HCL require subsequent lines of therapy in more than 50% of cases. Purine analogs allow significant response rates when applied first line and upon retreatment. Some patients may enjoy long lasting responses after one course of 2CdA and display no evidence of BRAF V600E mutation in peripheral blood. A PCR-based evaluation of the allelic burden in peripheral blood may provide information regarding disease activity over time. Figure Disclosures Cavo: Celgene, Janssen, Amgen, BMS, Abbvie, Takeda: Honoraria; Janssen, Celgene: Other: Travel Accommodations; Janssen, Celgene: Speakers Bureau; Janssen, Celgene, Amgen, Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees. Zinzani:TG Therapeutics: Honoraria, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kyowa Kirin: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Immune Design: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sandoz: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Verastem: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; MSD: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Eusapharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy; Celltrion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Portola: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

First Line Chemo-Free Therapy with the BRAF Inhibitor Vemurafenib Combined with Obinutuzumab Is Effective in Patients with Hcl

First Line Chemo-Free Therapy with the BRAF Inhibitor Vemurafenib Combined with Obinutuzumab Is Effective in Patients with Hcl

Immune recovery uveitis in a patient with herpes retinitis as a complication of hairy cell leukaemia

Abstract A 51 year-old man with hairy cell leukaemia was treated with pentostatin. While receiving the treatment, he was diagnosed with herpes retinitis in his right eye. After the last cycle of pentostatin the patient developed a mild vitritis and cystoid macular oedema. There were no signs of herpes retinitis reactivation. After excluding other possible causes of intraocular inflammation, a diagnosis of immune recovery uveitis was made. The patient was treated with 2-monthly retro-septal injections of triamcinolone, oral corticosteroids, intravitreal dexamethasone implants and, finally, pars plana vitrectomy. An immune recovery uveitis-like response is possible in HIV negative individuals. The immune reconstitution after the treatment of hairy cell leukaemia may have led to intraocular inflammation. Management of immune recovery uveitis is challenging and difficult. Pars plana vitrectomy may be necessary. Ophthalmologists should be alert to the possibility of immune recovery uveitis in HIV negative patients.

Respuesta similar a la uveítis de recuperación inmune en un paciente con retinitis herpética como complicación de una leucemia de células peludas

A 51 year-old man with hairy cell leukaemia was treated with pentostatin. While receiving the treatment, he was diagnosed with herpes retinitis in his right eye. After the last cycle of pentostatin the patient developed a mild vitritis and cystoid macular oedema. There were no signs of herpes retinitis reactivation. After excluding other possible causes of intraocular inflammation, a diagnosis of immune recovery uveitis was made.The patient was treated with 2-monthly retro-septal injections of triamcinolone, oral corticosteroids, intravitreal dexamethasone implants and, finally, pars plana vitrectomy.An immune recovery uveitis-like response is possible in HIV negative individuals. The immune reconstitution after the treatment of hairy cell leukaemia may have led to intraocular inflammation. Management of immune recovery uveitis is challenging and difficult. Pars plana vitrectomy may be necessary.Ophthalmologists should be alert to the possibility of immune recovery uveitis in HIV negative patients.

Hairy Cell Leukemia Treatment: The Past and the Present–Where We Are Now?

Hairy Cell Leukemia Treatment: The Past and the Present–Where We Are Now?

PS1164 SURVIVAL DISPARATIES IN HAIRY CELL LEUKEMIA ACROSS EUROPE: RESULTS OF RARECARENET‐‐A POPULATION‐BASED STUDY

Background:Around the early 1990 s, the purine nucleoside analogs (PNAs) cladribine (Piro, N Engl J Med, 1990) and pentostatin (Kraut, J Clin Oncol, 1989) revolutionized the treatment of hairy cell leukemia (HCL), a rare B‐cell derived lymphoproliferative malignancy. As a result, most patients with HCL can look forward to a normal life expectancy (Dinmohamed, Blood, 2018). However, information lacks on the contribution of PNA treatment on population‐level survival for HCL across Europe.Aims:Therefore, we conducted a population‐based study to assess relative survival (RS) among patients diagnosed with HCL across Europe.Methods:We selected all patients diagnosed with HCL in Europe between 2000 and 2007 from the publicly available RARECAREnet database that holds data from 94 cancer registries across 27 European countries (http://www.rarecarenet.eu). Follow‐up for survival was established up to January 1, 2009. Five‐year RS was the primary endpoint. We estimated 5‐year RS, with corresponding 95% confidence intervals (CIs), according to European region using the traditional cohort approach. RS is defined as the ratio of the overall survival of patients to the expected survival (ES) of a comparable group from the general population, matched to the patients with respect to age, sex, and time‐period. ES was estimated by the Ederer II method using country/registry‐specific lifetables, stratified by age, sex, and time‐period. RS was calculated for five European regions 3/4 namely (i) the UK and Ireland, and (ii) northern, (iii) central, (iv) southern, and (v) eastern Europe) 3/4 by pooling cases from the equivalent countries/registries.Results:Our analytical cohort included 4,387 patients with HCL, of whom 35%, 33%, 19%, 10%, and 3% from the UK and Ireland, and central, southern, eastern, and northern Europe, respectively. Overall, 5‐year RS was 90 (95% CI, 88%&gt;91%) in Europe, with higher RS in males (92%, 95% CI, 90%&gt;94%) than females (84%, 95% CI, 80%&gt;87%). Survival varied, albeit slightly across Europe, with 5‐year RS of 87% (95% CI, 84%&gt;90%), 88% (95% CI, 83%&gt;93%), 88% (95% CI, 86%&gt;91%), 93% (95% CI, 91%&gt;95%), and 94% (95% CI, 86%&gt;100%) in southern Europe, eastern Europe, the UK and Ireland, central Europe, and northern Europe, respectively. Also, as shown in Figure 1, survival varied across countries, especially in Slovenia when compared to the European average. However, particular country‐specific estimates should be interpreted with caution, as small sample sizes increase the wideness of 95% CIs.Summary/Conclusion:Collectively, in this large population‐based study, we demonstrated that excess mortality in HCL is comparatively low in Europe. However, modest survival disparities still exist across Europe in an era with well‐established PNA therapy. This might possibly suggest that access to or provision of PNA therapy is not entirely uniform across Europe. The current study provides a benchmark to assess whether survival inequities across Europe will diminish over time and excess mortality will decrease for this highly treatable malignancy through augmented access and provision of care.image

Moxetumomab pasudotox for the treatment of hairy cell leukemia

ABSTRACTIntroduction: 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.

Recombinant Immunotoxins against Latent Epstein Barr Virus Infections

Epstein Barr virus (EBV), commonly associated with acute infectious mononucleosis, is an oncogenic virus implicated in thousands of cancer‐related deaths every year worldwide. Estimates suggest that 90–95% of the population worldwide are infected with EBV, but acute infections are controlled with minimal symptoms by a healthy immune system. Like all herpesviruses, however, EBV persists in a latent state even after the acute infection has cleared. Studies have shown a definitive link between latent EBV infections and the development of certain cancers such as nasopharyngeal cancer and Burkitt's lymphoma, but there are currently no treatments for latent infections. A potential treatment for both latent EBV infections and EBV‐induced malignancies is antibody therapy targeted to virus‐specific membrane proteins. We have identified two EBV‐specific membrane proteins expressed on infected cells, LMP1 and LMP2, and are developing HEK293 cell lines constitutively expressing each of these proteins. We plan to develop recombinant immunotoxins (RITs) targeted to each of these proteins. RITs are fusion proteins comprised of an antibody and protein toxin designed to identify and kill specific populations of cells. RITs using the bacterial toxin Pseudomonas exotoxin A (PE) have been extensively studied. Several RITs are in clinical trials, and one (moxetumomab pasudotox) has recently received FDA approval for the treatment of Hairy Cell Leukemia. Using a previously developed anti‐LMP1 antibody, we have begun work to clone, express, and purify an anti‐LMP1 single‐chain variable fragment antibody joined recombinantly to a cytotoxic fragment of PE. We plan to evaluate this and other RITs as potential therapeutics for EBV‐related malignancies.Support or Funding InformationThis project was supported by the Towson University's Fisher College of Science and Mathematics.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Moxetumomab pasudotox: A first-in-class treatment for hairy cell leukemia.

Hairy cell leukemia is a rare indolent B-cell lymphoid malignancy. Durable remission can be obtained with purine analogues, but relapse is inevitable, and effective treatment options may be limited. Moxetumomab pasudotox is a recombinant CD22-targeting immunotoxin that has recently been approved by the United States Food and Drug Administration for the treatment of relapsed or refractory hairy cell leukemia. Approval was based on a pivotal phase III study in this unique patient population. Rationale for use, clinical trial data, and current treatment recommendations are detailed. Common adverse effects are reviewed, and management strategies for select adverse effects are suggested. Implications for contemporary practitioners are also provided, as use of this novel agent is likely to increase as follow-up studies are reported.

HSR19-086: Healthcare Costs and Resource Utilization Associated With Adverse Events Among Hairy Cell Leukemia Patients Treated With Purine Nucleoside Analogs

Background: Purine nucleoside analogs (PNAs) are highly effective for first-line treatment of hairy cell leukemia (HCL). In clinical trials of single PNAs, several adverse events (AEs) were reported; however, little is known regarding the costs and healthcare resource utilization (HRU) resulting from AEs in HCL patients (pts) treated with PNAs in non-clinical trial settings. Objective: Determine the costs and HRU of high incident and clinically important AEs associated with PNA therapy in HCL pts in the Truven MarketScan database. Methods: Adults (aged ≥18 years) with ≥2 HCL diagnosis codes ≥30 days apart during January 1, 2006–December 31, 2015 were included. Pts had ≥1 prescription claim for a PNA (cladribine or pentostatin ± rituximab) after HCL diagnosis date. First PNA claim date was defined as the index date. Pts had continuous health plan enrollment for ≥6 months at baseline and ≥12-months follow-up with no PNA in the baseline period. Pts were placed into cohorts based on the occurrence of myelosuppression (MSPN) and opportunistic infections (OI) as these were highest incident and clinically important AEs observed. Generalized linear models were used to compare outcomes during the 12-month follow-up. Results: Of the 219 pts with no history of MSPN, 101 developed MSPN (incidence [I]: 461 per 1000 pt-years) and of 619 pts with no history of OI, 26 developed OI (I: 42 per 1000 pt-years). Demographics were similar between pts with and without MSPN and OI. Pts who developed OI or MSPN had significantly higher inpatient admissions and costs (Table 1). Conclusions: PNA-treated HCL pts who developed MSPN or OI incurred higher HRU than those who did not develop either condition. This indicates the need for new therapeutic strategies to reduce HCL-treatment-associated toxicities.

Fludarabine and Rituximab in Relapsed or Refractory Hairy Cell Leukmia Variant: A Case Report and Review of Literature

Hairy cell leukemia (HCL) is a rare chronic B cell leukemia morphologically characterized by cells with an abundant cytoplasm and hair-like projections that can be found in the peripheral blood and bone marrow. The treatment for HCL is splenectomy or chemotherapy with the purine analogs pentostatin and cladribine. However, patients continue to relapse. Retreatment with the same or alternate purine analogs produces lower response rates and a shorter duration of response. Fludarabine is another purine analog widely used in treating indolent lymphoid cancers, often in combination with rituximab. Here, we report a case of HCL variant in a 60-year-old man who experienced multiple relapses after splenectomy and retreatment with cladribine. The patient was then treated with fludarabine and rituximab combination chemotherapy. After the treatment, he achieved complete remission that continued for 35 months.

Infection at the Time of Initial Therapy for Hairy Cell Leukemia Is Associated with Inferior Time to Next Treatment

Introduction: Hairy Cell Leukemia (HCL) is a rare, chronic hematological malignancy that makes up approximately 2% of all leukemias. HCL patients are at a markedly increased risk for infection related to a combination of disease-related and treatment-related immunosuppression which has been well described in the literature. However, the significance of infection prior to initiation of HCL therapy and its impact on the subsequent selection of HCL treatment, or outcomes, is not well described. Using the HCL patient data registry, we report here the impact of antecedent infection on the treatment patterns and outcomes of HCL patients.Methods: We evaluated adult (≥18 years) patients with HCL who had information regarding antecedent infections and subsequent HCL treatment during 1984-2018. The primary endpoint was progression-free survival (PFS-1). Secondary endpoint included time to next treatment (TTNT). PFS-1 was measured from the date of first HCL treatment to date of progression/death or last follow-up. TTNT was defined as the time from first HCL treatment to initiation of second HCL treatment. The study population was stratified into 3 groups based on the presence or absence of antecedent infections: no infection prior to first HCL treatment (no infection group), infection within 30 days prior to first HCL treatment (infection1 group) and infection >30 days prior to first HCL treatment (infection2 group). Fisher's exact test or Kruskal-Wallis test was used to compare the characteristics among the no infection and infection groups and the Cox proportional hazard model was used to evaluate the association with PFS-1 and TTNT.Results: A total of 205 HCL patients who had information regarding antecedent infections and subsequent HCL treatment were eligible for the study. Among these, 144 (70%) belonged to the no infection group, while 26 patients (13%) belonged to infection1 group and 35 (17%) to infection2 group. Patient characteristics are shown in Table 1 with a breakdown between the three groups. The majority of the patients were Caucasian with a male preponderance and had classic HCL.The patients in the infection1 group had a lower median WBC (K/uL) (1.9 vs 3.1 vs 2.9), particularly the absolute neutrophil count (K/uL) (0.4 vs 0.7 vs 0.8) and significantly lower median hemoglobin (gm%) (10.1 vs 12.2 vs 12.4) relative to the no infection and infection2 groups, respectively (p=0.01). Similarly, a greater proportion of patients in the infection1 group had significant comorbidities (including pulmonary, gastrointestinal and hepatic disease) relative to no infection and infection2 groups as shown in Table 1. The majority of patients received purine nucleoside analogs as their first HCL treatment (no infection group=92%, infection1 group=85%, infection2 group=94%).The median PFS-1 (in years) was better in the no infection group compared to the infection1 group but was not statistically significant (17.0 [95% CI=7.9-not reached (NR)] vs 8.8 [95% CI=4.2-NR], respectively, p=0.98, Figure 1). However, the median TTNT (in years) was significantly longer for HCL patients with no infection versus the infection1 group (6.3 [95% CI=5.4-7.8] vs 3.6 [95% CI=0.7-NR], respectively, p=0.001, Figure 1). On subgroup analysis, relative to the no infection group, median PFS-1 (in years) was not significantly different in infection1 group treated with Pentostatin (10.7 [95% CI=3.53-NR] vs NR [95% CI=1.38-NR], respectively, p=0.43), however, the median PFS-1 (in years) was shorter in the infection1 group treated with Cladribine (17.0 [95% CI=7.67-NR] vs 4.0 [95% CI=2.00-NR], respectively), although not reaching statistical significance (p=0.09) probably due to small sample size.Conclusion: In this large series of HCL patients who received treatment, we show that the patients who had infections at the time of HCL treatment have a significantly shorter TTNT. The reasons for this are unclear but may indicate that patients were unable to receive treatment in a timely manner because of the infection, or were unable to complete treatment because of complications. The significant difference in hemoglobin between the infection1 and other groups indicates the possibility that these patients had more advanced HCL at the time of diagnosis. These findings indicate the potential long term negative impact of infections in patients who need treatment for HCL and reinforce the need for careful management in this setting. [Display omitted] DisclosuresLozanski:Beckman: Research Funding; Coulter: Research Funding; Stem Line: Research Funding; Genentech: Research Funding; Novartis: Research Funding; BI: Research Funding. Andritsos:HCLF: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy.