Efficacy of rituximab in hairy cell leukemia treatment

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.

Retrospective Evaluation of Hairy Cell Leukemia Patients Treated with Three Different First-Line Treatment Modalities in the Last Two Decades: A Single-Center Experience

OBJECTIVE

In this study, we retrospectively analyzed the clinical outcome, treatment responses, infectious complications, and survival rates of 71 hairy cell leukemia (HCL) cases.

MATERIALS AND METHODS

Sixty-seven patients received a first-line treatment and 2-chlorodeoxyadenosine (cladribine-2-CdA) was administered in 31 cases, 19 patients received interferon-alpha (INF-α), splenectomy was performed in 16 cases, and rituximab was used in one.

RESULTS

Although the highest overall response rate (ORR) was observed in patients receiving 2-CdA upfront, ORRs were comparable in the 2-CdA, INF-α, and splenectomy subgroups. Relapse rates were significantly lower in patients who received first-line 2-CdA. The progression-free survival (PFS) rate with 2-CdA was significantly higher than in patients with INF-α and splenectomy, but we found similar overall survival rates with all three upfront treatment modalities. Infections including tuberculosis were a major problem.

CONCLUSION

Although purine analogues have improved the ORRs and PFS, there is still much progress to make with regard to overall survival and relapsed/refractory disease in patients with HCL.

Hairy cell leukemia-new genes, new targets

Hairy cell leukemia (HCL), a B cell malignancy comprising 2 % of all leukemias, has become quite exciting recently with regard to the development of new targets for therapy. This review will focus on advancements made within the past 1-2 years in targeted therapy for this disease. These advances may be grouped into two very difference categories, namely targeting of CD22 with the recombinant immunotoxin moxetumomab pasudotox, and targeting of the mutated BRAF component of the MAP kinase pathway. Moxetumomab pasudotox in phase I testing was recently reported to be associated with an overall response rate of 86 % and a complete remission (CR) rate of 46 % in 28 patients with relapsed and refractory HCL. Many of the CRs are without minimal residual disease (MRD). Severe or dose limiting toxicity was not observed on this trial, but a completely reversible and largely asymptomatic form of grade 2 hemolytic uremic syndrome occurred in two patients during retreatment. This agent has commenced phase III multicenter testing to validate its phase I results. An extensive number of studies have documented the V600E mutation in nearly all HCL patients, but not in similar hematologic malignancies. The thymidine kinase inhibitor vemurafenib, which inhibits the V600E mutant of BRAF, was reported to induce a CR in multiply relapsed and refractory HCL, with nearly complete clearing of MRD. One additional partial and one additional complete remission were subsequently reported.

Rituximab biosimilars

INTRODUCTION

Rituximab is a monoclonal antibody targeting CD20, used to treat B cell malignancies and B cell-mediated autoimmune diseases. Rituximab has the largest market of any monoclonal antibody therapeutic. Its patent will expire within the next few years and several manufacturers have already produced or are developing rituximab biosimilars that aim to match the innovator rituximab as closely as possible.

AREAS COVERED

In this review, we discuss key factors that determine the efficacy of rituximab therapy, potential technical challenges in the manufacture and evaluation of biosimilars, regulatory considerations regarding the review and approval of biosimilars, and the current status of biosimilar rituximab development by various manufacturers. Due to the nature of the topic, literature searches included conference abstracts, regulatory and industry websites as well as peer reviewed literature.

EXPERT OPINION

Cost is a key limitation of current biologics usage and there is a political impetus to the licensing of biosimilars. Concerns regarding potential dissimilarities of biosimilars are legitimate, but surmountable with techniques for in vitro, in vivo and clinical testing and more clearly defined regulatory requirements. These should provide reassurance to prescribers. However, the cost of manufacturing and licensing a biosimilar remains high and the reduction in cost may be more limited than for a non-biologic small molecule drug and its generic version. This cost reduction will be critical to the impact and use of rituximab biosimilars.

Hairy cell leukemia: current therapies and future directions

Hairy cell leukemia is a rare disease for which there are multiple treatment options. Purine nucleoside analogs (cladribine and pentostatin) are generally used for front-line treatment. Other active agents include interferon, rituximab and, although rarely, splenectomy. In the series published by Zinzani et al. in Cancer, the authors conclude that initial treatment for hairy cell leukemia should be maximized since these patients generally enjoy the highest complete response rates and the longest remission durations, and subsequent lines of therapy have lower response rates and more frequent relapses. However, evolving immunohistochemical and molecular diagnostic techniques, as well as criteria for evaluating response to therapy and clinical trials investigating chemoimmunotherapy, may result in clinicians re-evaluating how patients are treated in the front-line and when treatment should be initiated for relapsed patients.

Hairy cell leukemia: evaluation of the long-term outcome in 121 patients

BACKGROUND

Historically, the first treatment choices for hairy cell leukemia (HCL) were splenectomy and alpha-interferon. Recently, purine analogues (pentostatin and cladribine) changed radically the treatment modality, inducing complete and durable responses in the majority of patients.

METHODS

The authors analyzed the outcome of different lines of therapy in 121 HCL patients followed in their institute from 1986 to 2008, with a median follow-up of 105 months. Patients were divided into subgroups according to the number of treatments; Group A included 121 patients who underwent a front-line therapy, Group B patients (n =53) were treated with 2 lines, Group C patients (n = 34) with 3 lines, Group D patients (n = 17) with 4 lines, and Group E patients (n = 8) with 5 lines.

RESULTS

In Group A, 92 (77%) patients obtained a complete response (CR), 23 (18%) a partial response, and the remaining 6 (5%) a minor or no response; median duration of response was 2.7 years. In Group B, 53 relapsed patients achieved a second CR rate of 73.5%; median duration of response was 2.5 years. Group C contained 34 patients in a second relapse, with a CR rate after the third line of treatment of 70.5% (median duration of response, 2.2 years). In Group D, 11 (64.7%) patients obtained a CR (median duration of response, 1.6 years), and in Group E 4 (50%) of 8 patients achieved a CR (median duration of response, 1.3 years).

CONCLUSIONS

This study confirms the high risk (>40% of all patients) of retreatment of HCL patients and the need to maximize primary response.

Emerging drugs for rarer chronic lymphoid leukemias

BACKGROUND

Rarer indolent lymphoid leukemias include well defined mature B-cell and T-cell neoplasm with widely varying natural history and specific morphological, immunophenotypic and molecular characteristics. Among these are prolymphocytic leukemia (PLL), hairy cell leukemia (HCL) and its variants, large granular lymphocyte leukemia (LGLL) and adult T-cell leukemia/lymphoma (ATLL).

OBJECTIVE

To present current therapies and emerging drugs potentially useful in the treatment of rarer chronic lymphoid leukemias.

METHODS

After searching MEDLINE, PubMed and the Current Contents database, and conference proceedings from the previous 3 years of the American Society of Hematology (ASH), the European Society of Hematology (EHA) and the American Society of Clinical Oncology (ASCO) were searched manually; articles written in English and additional relevant publications were then selected.

RESULTS/CONCLUSION

New drugs including monoclonal antibodies (mAbs), new purine analogs, small molecules targeting specific molecular targets and other agents are included. Future research should focus on the novel therapeutic strategies based on the molecular pathogenic mechanisms and the development of new targeted therapies for each distinct chronic lymphoid leukemia.

The role of rituximab in combination with pentostatin or cladribine for the treatment of recurrent/refractory hairy cell leukemia

BACKGROUND

The purine analogs pentostatin and cladribine have revolutionized the treatment of hairy cell leukemia (HCL) with overall responses in greater than 85% of patients and a median progression-free survival of up to 15 years. They continue to be effective at second- and even third-line therapy; however, alternative treatments are needed for patients who are or have become refractory to these agents or whose remissions are shorter with each course of therapy.

METHODS

The authors conducted a retrospective review of 8 patients who received pentostatin or cladribine combined concurrently (n = 6 patients) or sequentially (n = 2 patients) with rituximab at second-line therapy (n = 3 patients) and at subsequent lines of therapy (n = 5 patients). Results from a previously reported database of 219 patients with HCL (73 patients who received second-line therapy and 20 patients who received third-line therapy) were used as a historic control group against which to measure benefit.

RESULTS

All 8 patients responded to therapy, with 7 complete responses (CRs) (87.5%) and minimal toxicity. All patients who had CRs were negative for minimal residual disease (MRD). At a median follow-up of 29 months (range, 5-39 months) 1 patient developed recurrent disease, and the estimated 2-year recurrence rate was 20% (0% after second-line therapy and 25% after subsequent lines of therapy). In the historic control group, the CR rates were 70% after second-line therapy and 45% after third-line therapy, and the recurrence rates at 2 years were 15% and 33%, respectively.

CONCLUSIONS

The combination of purine analogs with rituximab was safe and effective for patients with recurrent and/or refractory HCL, and the current results suggested an added benefit compared with standard treatment.

BL22 and lymphoid malignancies

BL22 is a recombinant immunotoxin containing a truncated form of the bacterial toxin Pseudomonas exotoxin A attached to an Fv fragment of an anti-CD22 monoclonal antibody. Its mechanism of action involves binding to CD22, being internalized into the target cell by endocytosis, being processed to generate a free toxin fragment which is translocated into the cytoplasm, and finally induction of cell death by catalytic inactivation of elongation factor 2. In phase-I testing BL22 was very active in chemoresistant hairy-cell leukemia (HCL), with 19 (61%) of 31 patients achieving complete remission (CR). The low blood counts (cytopenias) which are characteristic of HCL improved in all complete and partial responders. Dose-limiting toxicity in HCL was due to a reversible hemolytic uremic syndrome (HUS), observed only during cycles 2 or 3. Already under way are a phase-II trial in HCL and phase-I trials in chronic lymphocytic leukemia (CLL) and acute lymphocytic leukemia (ALL) administering BL22 in a modified protocol in an effort to prevent HUS.

Monoclonal antibody therapy for hairy cell leukemia

The use of MoAb therapy for the treatment of HCL offers great promise and potential for improving progression-free survival. Rituximab has activity in the setting of previously treated HCL and the ability to eradicate MRD after 2-CdA given as frontline therapy. Alemtuzumab, epratuzumab, Hu-Max-CD20, and other candidate MoAb's should be studied in HCL. Appropriate pharmacologic investigation, use of antigen modulation, and assessments of soluble antigen levels should be considered with future clinical trial s of MoAb's in HCL to optimize therapeutic strategies.

Current treatment options in hairy cell leukemia and hairy cell leukemia variant

Hairy cell leukemia (HCL) is a chronic B-cell lymphoproliferative disorder characterized by splenomegaly, pancytopenia and circulating lymphocytes displaying prominent cytoplasmic projections. HCL has usually an indolent course and the patients with asymptomatic disease do not require therapy. Treatment of progressive symptomatic HCL includes a variety of pharmacological approaches such as interferon-alpha (IFN-alpha), pentostatin (DCF) and cladribine (2-CdA), which have significantly improved the disease prognosis. 2-CdA and DCF seem to induce a similar high response rate and a long overall survival. They are also active in relapsed patients. More recently high activity of anti-CD20 monoclonal antibody (rituximab) and anti-CD25 (LMB-2) and anti-CD22 (BL-22) immunotoxins have increased the number of therapeutic options for HCL. Splenectomy may be still indicated in patients with massive, symptomatic splenomegaly or results in severe cytopenia. IFN-alpha may have a place in patients with very severe cytopenia, in HCL in pregnancy and in patients who have failed prior therapy with purine nucleoside analogs. HCL variant (HCL-V) is a distinct clinico-pathological entity which seems to be resistant to IFN-alpha and purine nucleoside analogs - DCF and 2-CdA. However, preliminary observations suggest that monoclonal antibodies - rituximab and BL-22 immunotoxin are highly active in this disorder even refractory to 2-CdA. In this review current therapeutic strategies in HCL and HCL-V are presented.

Monoclonal antibodies as therapeutic agents for cancer

Targeted therapies are the focus of much research in oncology. After the development of imatinib for the treatment of chronic myeloid leukaemia, biological therapies that target tumour-associated antigens give hope for improvement of survival in many cancers. At the American Society of Clinical Oncology (ASCO) conference in 2003, data for the antibodies bevacizumab and cetuximab highlighted promising results in clinical trials, including an improvement in survival for metastatic colorectal cancer. Positive results for other antibodies in various stages of clinical development provide hope that anticancer antibodies will have an effect on clinical oncology practice in the next 10 years.

Phase 2 study of rituximab in the treatment of cladribine-failed patients with hairy cell leukemia

Hairy cell leukemia (HCL) is an indolent B-cell neoplasm, strongly expressing CD20. Despite initial very high response rates following cladribine, many patients (pts) ultimately relapse. Having relapsed after prior treatment with cladribine, 24 HCL pts (21 male, 3 female) with a median age of 53.5 years were treated with rituximab at 375 mg/m2 intravenously weekly for 4 weeks. Of the pts, 3 (13%) achieved complete remissions and 3 (13%), partial responses. Thus, 6 (25%) of 24 pts achieved a response following rituximab. At a median follow-up of 14.6 months, 2 responders have relapsed; median time to relapse was not yet reached. The only grade III or IV toxicities demonstrated were culture-negative febrile neutropenia, transient and reversible disseminated intravascular coagulation related to rituximab administration, and a diverticular abscess, each in single patients. Of 18 nonresponders, 9 pts subsequently received other treatments; 5 pts were retreated with cladribine, 3 underwent splenectomy, and 1 received pentostatin. Follow-up data are available on 7 of these 9 patients; all 7 patients achieved improvements in hematologic parameters. Rituximab, administered at this dose and schedule, has only modest single-agent activity in cladribine-failed HCL patients when compared with other agents active in this disease.

Circulating CD20 is detectable in the plasma of patients with chronic lymphocytic leukemia and is of prognostic significance

CD20 is a 33- to 36-kDa transmembrane phosphoprotein involved in the activation, proliferation, and differentiation of B lymphocytes. The predicted amino acid sequence of the CD20 suggests 4 transmembrane-spanning regions with both N- and C-termini located in the cytoplasm. We demonstrate herein that significant levels of circulating CD20 (cCD20) can be detected in the plasma of patients with chronic lymphocytic leukemia (CLL) and that cCD20 interferes with the binding of rituximab, a humanized anti-CD20 monoclonal antibody, to CLL cells. An enzyme-linked immunosorbent assay (ELISA) was developed to measure circulating cCD20 levels in the plasma. We measured cCD20 levels in the plasma of 180 patients with CLL and correlated these levels with clinical characteristics and outcome. Circulating CD20 levels correlated positively with beta(2)-microglobulin level (p =.006) and percentage of CD38(+) cells (p =.03) and negatively with platelet count (p =.004) and hemoglobin level (p =.02). Patients with advanced Rai (III/IV) or Binet (C) stage disease had significantly higher levels of cCD20 than did patients with earlier-stage disease (P =.01 and P =.006, respectively). There was no correlation between cCD20 level and age, lymphocyte count, or white blood cell count. Using a recursive classification method, we found that patients with a cCD20 level more than 1875 nM/L had significantly shorter survival than those with cCD20 1875 nM/L or below (P =.01). The prognostic value of cCD20 was independent of Rai staging or hemoglobin level. Prospective evaluation is indicated to establish whether rituximab dosing should be adjusted according to cCD20 levels.

Immunobiological treatments of hairy-cell leukaemia

Hairy cell leukaemia (HCL) is extremely responsive to purine analogue theropy developed during the early 1990s, but some patients have emerged with resistance to purine analogues. For these patients, as well as for those with primarily refractory HCL, new treatments are necessary. Several new therapeutic options have been developed for the salvage treatment of HCL. These include recombinant immunotoxins and unlabelled monoclonal antibodies (mAbs). Recombinant immunotoxins are chimeric proteins in which the Fv portion of a mAb is fused to a 38 kDa fragment of Pseudomonas exotoxin A. Two recombinant immunotoxins, BL22 and LMB-2, targeting CD22 and CD25, respectively, have demonstrated efficacy in patients with HCL resistant to purine analogues. BL22 was reported to induce complete remissions (CRs) in the majority of patients with cladribine-resistant HCL; its clinical efficacy and safety profile are currently being further defined. The unlabelled mAb rituximab has also been reported to induce responses in the majority of HCL patients treated, and several CRs have been observed.

Monoclonal antibody therapy of haematological malignancies

Over the past decade the potential for delivering targeted therapy against malignant disease by the use of monoclonal antibodies (MAbs) has begun to be realised. Haematological malignancies, because of the relative accessibility of the malignant cell in blood and bone marrow and the understanding of haemopoietic lineage-specific antigens, have provided a successful testing ground for this therapy. There have been many technical developments which have allowed the safe delivery of more potent antibody constructs. The development of human or chimeric antibodies has largely overcome the problems associated with host immune responses to rodent-derived MAbs. Protein engineering to combine MAbs with other biologically active molecules such as radioisotopes, toxins, chemotherapy and cytokines, has made available a new range of agents with clinical activity. The purpose of this review is not to give a catalogue of all therapeutic antibodies but rather to outline the principles of this approach, the current state of knowledge, and possible directions for future development. First, the general requirements and strategies for use of both unmodified and conjugated MAbs are discussed, followed by a summary of the trial data in specific lymphoid and myeloid haemopoietic malignancies. The focus is on MAbs that now have an accepted use in clinical practice, with some discussion of newer MAbs under development. Vaccination strategies and the role of MAbs in bone marrow transplantation are not discussed in detail. The trials of the next decade will address issues such as: whether clinical activity translates into improved survival; the optimal strategies and timing for clinical use; whether increasing potency of MAbs (as in radio- and immunoconjugates) will increase toxicity and, finally, what other potential molecules, such as those influencing cell growth and death, may be targeted.

Advances in the treatment of hairy-cell leukaemia

Hairy-cell leukaemia (HCL) is an uncommon B-cell chronic lymphoproliferative disorder that accounts for about 2% of all leukaemias. Although the disease is generally indolent in its natural course, the majority of patients require treatment for life-threatening infections due to pancytopenia or symptomatic splenomegaly. During the past 20 years, remarkable progress has been made in the treatment of HCL. Since the introduction of interferon-alpha, splenectomy, which was formerly the standard therapy, has been rarely used. With the purine analogues cladribine and pentostatin, response rates are even better than with interferon-alpha and long-lasting remissions can be achieved in most patients. Therefore, these agents are now considered the treatment of choice. Recently, immunotherapeutic approaches which use monoclonal antibodies have increased the number of therapeutic options for HCL and offer promising salvage strategies for patients who relapse or who are refractory to treatment with purine analogues. In this review the different treatment options available are discussed and recommendations for the clinical management of the HCL are summarised.

Rituximab, a chimaeric anti-CD20 monoclonal antibody, in the treatment of hairy cell leukaemia

The introduction of first alpha-interferon and later the purine analogues has revolutionized the treatment of hairy cell leukaemia (HCL). However, there are still some patients that initially or eventually fail to respond and, thus, there is a need for alternative treatment modalities. We have treated 11 HCL patients (eight relapsing and three newly diagnosed) with a chimaeric monoclonal antibody, rituximab, in a dose of 375 mg/m2 once a week for 4 weeks. The response rate was seven out of eleven (64%) with six complete remissions and one partial remission, all which have lasted between 0 and 34 months (median 14 months). Rituximab appears promising in the treatment of HCL and warrants further studies.

Rituximab: review and clinical applications focusing on non-Hodgkin's lymphoma

Rituximab (Rituxan) was the first monoclonal antibody approved for cancer therapy and the first single-agent approved for therapy of lymphoma. When combined with CHOP, rituximab is the only drug that has been shown to improve survival of a subpopulation of patients with diffuse large cell lymphoma during the last three decades. It was approved by the FDA for the treatment of patients with relapsed or refractory low-grade or follicular, CD20-positive, B-cell non-Hodgkin's lymphoma in 1997. Rituximab is also being studied in many other B-cell malignancies alone and in combination with other agents. Furthermore, it is currently being evaluated in several nonmalignant diseases, such as autoimmune disorders. This review will focus on the role of rituximab in patients with non-Hodgkin's lymphoma.

Hairy cell leukemia: treatment prospects

The recent advances in the management of hairy cell leukemia, a chronic and indolent B-cell lymphoproliferative disorder are reviewed. The introduction of alpha-interferon, purine analogs and recombinant monoclonal antibodies/immunotoxins has dramatically improved the outcome in a disease that once had a dismal prognosis. The underlying genetic defect remains unknown.

An on-site audit of the South African trial of high-dose chemotherapy for metastatic breast cancer and associated publications

PURPOSE

The randomized study reported by Bezwoda et al of high-dose chemotherapy (HDC) for treatment of metastatic breast cancer was audited on site to verify the study results. Additional published studies were reviewed to determine whether they had been subject to the required institutional oversight.

PATIENTS AND METHODS

Ninety patients were reported to have been randomized and treated on this trial. A log of the names, hospital numbers, entry dates, and regimen received had been provided by the principal investigator. A search of more than 15,000 sets of medical records available from two Johannesburg hospitals was performed to locate records for as many of these 90 patients as possible. Standard auditing techniques were used. Additional clinical trials published by Bezwoda were compared against the minutes of the University of the Witwatersrand Committee for Research on Human Subjects to verify review and approval.

RESULTS

Records for only 61 of the 90 patients could be found. Of these 61, only 27 had sufficient records to verify eligibility for the trial by the published criteria. Of these 27, 18 did not meet one or more eligibility criteria. Only 25 patients appeared to have received their assigned therapy temporally associated with their enrollment date, and all but three of these 25 received HDC. The treatment details of individual patients were at great variance from the published data. Nine other trials reported by Bezwoda were not reviewed or approved by the appropriate institutional committee despite statements to the contrary in the publications.

CONCLUSION

The multiple publications of this study do not report verifiable data, and nine other publications coauthored by the principal investigator contain at least one major untrue statement.

Human leukocyte differentiation antigens as therapeutic targets: the CD molecules and CD antibodies

The cell membrane presents an attractive target in a number of different disease situations. Most obviously, malignant cells may be killed by damaging their cell membranes. There are also more subtle, though effective, ways of rendering cells harmless by engaging proteins at the cell surface. The cells of the immune system may be targeted, for example to stop a damaging immune reaction, such as acute inflammation or rejection of a transplanted organ. If we are to make the best use of the opportunities to modulate disease by targeting the cell membrane, we need a detailed understanding of the many proteins, glycoproteins and glycolipids that are attached to or inserted in the cell membrane. The CD (cluster of differentiation) Workshops, more properly known as the HLDA (Human Leukocyte Differentiation Antigens) Workshops have, since 1982, focussed on the study of the membrane molecules of leukocytes, including the major cells of the immune system and malignant cells derived from them. The scope has extended to molecules on endothelium which are important in interaction with leukocytes. Many of the molecules characterised as leukocyte antigens are also expressed on other tissue. The approaches developed by the HLDA Workshops are useful in the study of the molecular composition and function of cells of other organ systems. Some of the antibodies produced in order to study the CD molecules have proved useful as therapeutic agents. This review describes the CD system, how it has developed and what it means and introduces the field of therapy based on antibodies against CD or similar molecules. The author is responsible for organising the next (8th) HLDA Workshop and invites readers to suggest ways in which the therapeutic relevance of the Workshop may be enhanced.