Quantitation of minimal disease levels in chronic lymphocytic leukemia using a sensitive flow cytometric assay improves the prediction of outcome and can be used to optimize therapy

Consolidation and maintenance immunotherapy with rituximab improve clinical outcome in patients with B-cell chronic lymphocytic leukemia

BACKGROUND

Rituximab in sequential combination with fludarabine (Flu) allowed patients with B-cell chronic lymphocytic leukemia (B-CLL) to achieve higher remission rates and longer response duration. Based on their recent experience in indolent non-Hodgkin lymphomas, in this study, the authors attempted to demonstrate whether consolidation/maintenance therapy with rituximab could prolong the response duration in this patient population.

METHODS

This Phase II study was based on a consolidation/maintenance therapy with rituximab for patients in complete remission (CR) or partial remission (PR) who were positive for minimal residual disease (MRD), as determined by flow cytometry. Seventy-five symptomatic, untreated patients with B-CLL received 6 monthly cycles of Flu (25 mg/m(2) for 5 days) followed by 4 weekly doses of rituximab (375 mg/m(2)). Then, 28 patients who were positive for MRD were consolidated with 4 monthly cycles of rituximab (375 mg/m(2)) followed by 12 monthly low doses of rituximab (150 mg/m(2)).

RESULTS

Based on National Cancer Institute criteria, 61 of 75 patients (81%) achieved a CR, 10 of 75 patients (13%) had a PR, and 4 of 75 patients (5%) had either no response or disease progression. MRD-positive patients in CR or PR who received consolidation therapy (n = 28 patients) had a significantly longer response duration (87% vs 32% at 5 years; P = .001) compared with a subset of patients who did not receive consolidation therapy (n = 18 patients). All patients experienced a long progression-free survival from the end of induction treatment (73% at 5 years). It was noteworthy that, within the subset of ZAP-70-positive patients, MRD-positive, consolidated patients (n = 12 patients) had a significantly longer response duration (69% vs 0% at 2.6 years; P = .007) compared with MRD-positive, unconsolidated patients (n = 11 patients).

CONCLUSIONS

The addition of a consolidation and maintenance therapy with rituximab prolonged response duration significantly in patients with MRD-positive B-CLL.

The expanding role of rituximab and radioimmunotherapy in the treatment of B-cell lymphomas

The role of rituximab in the treatment of B-cell lymphomas has rapidly emerged from the relapsed setting to first-line combination regimens across the broad range of histologic subtypes. The role of maintenance rituximab in indolent lymphomas after first-line therapy needs to be defined along with the integration of radioimmunotherapy into the first-line therapeutic regimens. As mechanisms of action/resistance to monoclonal antibody therapy are better understood, approaches to predicting response and optimizing combination therapy to overcoming primary and acquired resistance may be developed.

Minimal residual disease assessment in chronic lymphocytic leukaemia

The concept of minimal residual disease (MRD) eradication in chronic lymphocytic leukaemia (CLL) is a relatively new one, as conventional therapy with alkylating agents is relatively ineffective and responding patients almost always have a significant tumour burden remaining at the end of treatment. However, a variety of novel therapies is now yielding higher response rates, and responses of better quality are now routinely achieved. This progress in therapy has been paralleled by an improvement in laboratory assays, allowing detection of CLL cells to levels as low as ten CLL cells in a million leukocytes. In this chapter we briefly review the existing methods for MRD assessment, the clinical relevance of MRD eradication in CLL, and the therapies available to attain this endpoint.

Chemoimmunotherapy of chronic lymphocytic leukemia

The past two decades have seen a major paradigm shift in the therapy of chronic lymphocytic leukemia (CLL), with the treatment goal shifting from symptom palliation to the attainment of maximal disease control using the most effective frontline regimens available, thus prolonging survival and possibly leading to cure. The most potent therapeutic regimens developed to date include the chemoimmunotherapy combinations incorporating purine analogs and monoclonal antibodies. We review the evolution of modern chemoimmunotherapy for CLL, and discuss current research directions for further refining the potency of these regimens.

Stem-cell transplantation in chronic lympocytic leukaemia

Excellent response rates are now achieved with modern chemoimmunotherapeutic approaches in chronic lymphocytic leukaemia (CLL), but the disease remains incurable. Younger patients and those with adverse prognostic factors will die from their disease, and are therefore candidates for clinical trials investigating the potential role of haematopoietic stem-cell transplantation (SCT) in the management of their disease. Autologous SCT is feasible and safe, but there is a high incidence of subsequent relapse. Myeloablative allogeneic SCT is associated with high treatment-related morbidity and mortality but few late relapses. Attempts to exploit the graft-versus-leukaemia effect of allogeneic donor cells but to reduce the toxicity are being explored in studies of reduced-intensity conditioning allogeneic SCT in CLL. With many potential treatments available, appropriate patient selection and the timing of SCT in the management of CLL remain controversial and the focus of ongoing clinical trials.

The normal counterpart to the chronic lymphocytic leukemia B cell

Chronic lymphocytic leukemia (CLL) is characterized by the monoclonal expansion of small mature-looking B cells that accumulate in the blood, marrow, and lymphoid organs, and have a remarkable phenotypic homogeneity. By definition, CLL cells co-express CD5 and CD23 with faint to undetectable amounts of monoclonal surface immunoglobulins (sIg). The concept of phenotypic homogeneity has been reinforced by gene expression profiling data, which suggest that the pathogenesis of CLL has to be associated with a fairly common mechanism of transformation. In recent years the biology of CLL has been enriched by an unprecedented flurry of new observations that are leading to a better understanding of the natural history of the disease. Still CLL cells have so far defied any attempt to satisfactorily answer the simple time-honored question of what their cell of origin is. It is the purpose of this review to discuss the features a cell must possess to be considered with reasonable approximation the normal counterpart of a CLL B cell.

Molecular genetic analysis of haematological malignancies II: mature lymphoid neoplasms

Molecular genetic techniques have become an integral part of the diagnostic assessment for many lymphomas and other chronic lymphoid neoplasms. The demonstration of a clonal immunoglobulin or T cell receptor gene rearrangement offers a useful diagnostic tool in cases where the diagnosis is equivocal. Molecular genetic detection of other genomic rearrangements may not only assist with the diagnosis but can also provide important prognostic information. Many of these rearrangements can act as molecular markers for the detection of low levels of residual disease. In this review, we discuss the applications of molecular genetic analysis to the chronic lymphoid malignancies. The review concentrates on those disorders for which molecular genetic analysis can offer diagnostic and/or prognostic information.

Alemtuzumab in chronic lymphocytic leukemia

QUESTIONS

With respect to outcomes such as survival, response rate, response duration, time to progression, and quality of life, is alemtuzumab a beneficial treatment option for patients with B-cell chronic lymphocytic leukemia (cll)?What toxicities are associated with the use of alemtuzumab?Which patients are more likely-or less likely-to benefit from treatment with alemtuzumab?

PERSPECTIVES

Evidence was selected and reviewed by one member of the Hematology Disease Site Group (dsg) of Cancer Care Ontario's Program in Evidence-Based Care (pebc) and by methodologists. The practice guideline report was reviewed and approved by the Hema-tology dsg, which comprises hematologists, medical and radiation oncologists, and a patient representative. As part of an external review process, the report was disseminated to obtain feedback from practitioners in Ontario.

OUTCOMES

Outcomes of interest were overall survival, quality of life, response rates and duration, and adverse event rates.

METHODOLOGY

A systematic review of the medline, embase, HealthStar, cinahl, and Cochrane Library databases was conducted to search for primary articles and practice guidelines. The evidence informed the development of clinical practice recommendations. The evidence review and recommendations were appraised by a sample of practitioners from Ontario, Canada, and were modified in response to the feedback received. The systematic review and modified recommendations were approved by a review body within the pebc.

RESULTS

The literature review found no published randomized controlled trials (rcts) that evaluated alem-tuzumab alone or in combination with other chemotherapeutic agents for the treatment of relapsed or refractory cll. One rct evaluated alemtuzumab administered to consolidate a complete or partial response to first-line fludarabine-containing chemotherapy. That study was stopped early because of excessive grades 3 and 4 infection-related toxicity in the alemtuzumab arm. Patients receiving alemtuzumab experienced significantly improved progression-free survival as compared with patients undergoing observation. Six single-arm studies evaluated disease response with administration of alemtuzumab as a single agent in the treatment of patients with relapsed or refractory cll post-fludarabine. The pooled overall response rate was 38% (complete response: 6%; partial response: 32%). Adverse events associated with the use of alemtuzumab were commonly reported and included serious infusion-related, hematologic, and infection-related toxicities.

RECOMMENDATION

This evidence-based recommendation applies to adult patients with B-cell cll. Treatment with alemtuzumab is a reasonable option for patients with progressive and symptomatic cll that is refractory to both alkylator-based and fludarabine-based regimens.

QUALIFYING STATEMENTS

The evidence supporting treatment with alemtuzumab comes principally from case series that evaluated disease response as the primary outcome measure. Patients should be informed that any possible beneficial effect of alemtuzumab on other outcome measures such as duration of response, quality of life, and overall survival are not supported in evidence and currently remain speculative. Treatment with alemtuzumab is associated with significant and potentially serious treatment-related toxicities. Patients must be carefully informed of the uncertain balance between potential risks of harm and the chance for benefit reported in studies. Given the current substantial uncertainty in this balance, patient preferences will likely play a large role in determining the appropriate treatment choice. Given the potential toxicities associated with alemtuzumab, and given the limited nature of the agent's testing in clinical trials in broad populations of patients with cll, the use of alemtuzumab in patients with important comorbidities may be associated with excessive risks.

International standardized approach for flow cytometric residual disease monitoring in chronic lymphocytic leukaemia

The eradication of minimal residual disease (MRD) in chronic lymphocytic leukaemia (CLL) predicts for improved outcome. However, the wide variety of MRD techniques makes it difficult to interpret and compare different clinical trials. Our aim was to develop a standardized flow cytometric CLL-MRD assay and compare it to real-time quantitative allele-specific oligonucleotide (RQ-ASO) Immunoglobulin heavy chain gene (IgH) polymerase chain reaction (PCR). Analysis of 728 paired blood and marrow samples demonstrated high concordance (87%) for patients off-therapy. Blood analysis was equally or more sensitive than marrow in 92% of samples but marrow analysis was necessary to detect MRD within 3 months of alemtuzumab therapy. Assessment of 50 CLL-specific antibody combinations identified three (CD5/CD19 with CD20/CD38, CD81/CD22 and CD79b/CD43) with low inter-laboratory variation and false-detection rates. Experienced operators demonstrated an accuracy of 95.7% (specificity 98.8%, sensitivity 91.1%) in 141 samples with 0.01-0.1% CLL. There was close correlation and 95% concordance with RQ-ASO IgH-PCR for detection of CLL above 0.01%. The proposed flow cytometry approach is applicable to all sample types and therapeutic regimes, and sufficiently rapid and sensitive to guide therapy to an MRD-negativity in real time. These techniques may be used as a tool for assessing response and comparing the efficacy of different therapeutic approaches.

Transplantation in chronic lymphocytic leukemia

Although there have been no randomized trials comparing the outcome of stem cell transplantation (SCT) with standard chemotherapy for patients with chronic lymphocytic leukemia (CLL), increasingly, both autologous and allogeneic SCT approaches are being explored in this disease. Clinical trials have demonstrated that these approaches are feasible, but current data suggest that autologous transplantation is not curative and myeloablative SCT, although offering the potential for cure, is associated with high treatment-related mortality. There is a clear demonstration of a graft-versus-leukemia effect in CLL, with encouraging results seen after SCT with reduced-intensity conditioning. Because no other treatment modalities are currently capable of improving survival in this disease, the treatment of choice for younger patients with poor-risk CLL may well be SCT, but continued enrollment of appropriate patients into well-designed clinical trials is vital to compare advances in SCT with the advances occurring in chemoimmunotherapy in CLL.

Alemtuzumab in chronic lymphocytic leukemia

Alemtuzumab is a humanized monoclonal antibody specific for CD52, a glycosylphosphatidylinositol-anchored, lymphocyte-surface glycoprotein. Administration of alemtuzumab to patients with chronic lymphocytic leukemia depletes normal and neoplastic lymphocytes from the blood, spleen and marrow, but appears to be less effective in resolving lymphadenopathy. Owing to its activity in clearing leukemia cells of patients who are refractory to purine analogs, such as fludarabine, alemtuzumab became the first and only monoclonal antibody approved by the US FDA and other regulatory authorities for the treatment of chronic lymphocytic leukemia. Here we review the results of clinical studies evaluating the activity and safety of alemtuzumab when used alone or in combination with other antileukemia agents for the treatment of this disease.

Clinical Utility of Autopsy after Hematopoietic Stem Cell Transplantation

Autopsy is the gold standard for establishing the cause of death. We present results of the largest retrospective review of complete autopsies of subjects after hematopoietic stem cell transplantation to better define the role of the autopsy in discovering a missed diagnosis. We reviewed the medical chart and autopsy records of 111 patients who had undergone hematopoietic stem cell transplantation from July 1986 to June 2003 from a single center. We compared the cause of death as charted by the clinical team with data obtained from postmortem chart review and autopsy reports. Of 29 (26%) cases when the premortem and postmortem major diagnoses did not agree, only 4 (4%) autopsy records provided data that might have led to the initiation of new treatments, and none of these diagnoses would be missed today with more sensitive and specific diagnostics and improved supportive care. Although autopsies after transplantation can be important educational, research, and epidemiologic tools and provide an emotional benefit to patient's families, in our series they rarely provided missed diagnoses that would alter the management of subsequent patients. Improvements in noninvasive tests for relapse or occult infections may further erode the role of autopsies in discovering missed diagnoses.

Four-color flow cytometric analysis of myeloma plasma cells

We monitored the behavior of residual myeloma plasma cells in patients with multiple myeloma after high-dose therapy and autologous or allogeneic transplantation using 3 methods of a flow cytometric technique using 4-color staining, immunofixation, and polymerase chain reaction approaches. We analyzed 17 cases by a relatively simple flow cytometric technique using CD38/CD45/CD19/CD56. Detectable myeloma plasma cells were found in 5 patients at diagnosis and 9 patients after treatment. Of 14 cases, 9 (64%) had CD19-CD56+ myeloma plasma cells, and 5 (36%) of 14 had CD19-CD56- myeloma plasma cells. When 37 bone marrow samples that had less than 5% myeloma plasma cells were assessed, myeloma plasma cells were detected in all 20 immunofixation-positive cases and 3 of 17 immunofixation-negative cases (P = .002). All 4 polymerase chain reaction-negative samples characterized as immunofixation-negative contained no detectable myeloma plasma cells. Flow cytometry can provide effective information to detect low levels of myeloma plasma cells.

Minimal residual disease in chronic lymphocytic leukaemia: is it ready for primetime?

New therapeutic modalities have substantially improved response rates and outcomes in chronic lymphocytic leukaemia (CLL), yet the mindset remains that palliation is the only goal of therapy because the disease is considered incurable. Ultimately, all patients relapse despite achieving an initial response, as minimal residual disease (MRD) persisting after therapy eventually evolves into morphological and clinical recurrence. The emergence of immune-based combination therapies capable of inducing molecular remissions, the availability of highly sensitive assays that detect MRD, and emerging data showing a longer duration of response or longer survival in patients with no detectable disease, suggest that eradicating MRD may be a reasonable option for some patients. Moreover, novel biological prognostic markers have divided CLL into favourable and unfavourable subtypes, arguing in favour of defining different goals of therapy for different patients. Clinicians are increasingly challenged with the task of how best to incorporate MRD assessment into clinical practice, especially in an era when these novel prognostic factors exist. This review summarises the current understanding of MRD from a clinical standpoint, suggests that MRD eradication maybe a reasonable option for some patients, and argues in favour of designing large randomised studies to determine whether MRD-negative remission improves outcome.

The detection and significance of minimal residual disease in acute and chronic leukemia

Minimal residual disease (MRD) can be detected in many patients with leukemia who have achieved complete remission as defined by conventional pathology examination. The detection of MRD, be it by flow cytometry or by polymerase chain reaction assays, has now been found to be associated with subsequent relapses in most leukemia subtypes, either following chemotherapy or following hematopoietic stem cell transplantation. These assays are now increasingly used in clinical trial design to optimize therapy and provide a novel way to assess treatment efficacy.

Flow cytometric protein expression profiling as a systematic approach for developing disease-specific assays: identification of a chronic lymphocytic leukaemia-specific assay for use in rituximab-containing regimens

Depletion of disease below the levels detected by sensitive minimal residual disease (MRD) assays is associated with prolonged survival in chronic lymphocytic leukaemia (CLL). Flow cytometric MRD assays are now sufficiently sensitive and rapid to guide the duration of therapy in CLL, but generally rely on assessment of CD20 expression, which cannot be accurately measured during and after therapeutic approaches containing rituximab. The aim of this study was to use analytical software developed for microarray analysis to provide a systematic approach for MRD flow assay development. Samples from CLL patients (n=49), normal controls (n=21) and other B-lymphoproliferative disorders (n=12) were assessed with a panel of 66 antibodies. The DNA-Chip analysis program was used to identify discriminating antibodies, with hierarchical cluster analysis to identify complementary combinations. An iterative process was used: increasing numbers of patients were assessed with smaller, more targeted antibody panels until a highly specific combination (CD81/CD22/CD19/CD5) was identified. This combination was as sensitive and specific as previously reported assays and potentially applicable to blood and marrow samples from patients treated with current therapeutic approaches including rituximab. This approach to the identification of disease-specific antibody combinations for MRD analysis is readily applicable to a variety of haematological disorders.

Chronic lymphocytic leukemia: diagnosis and treatment

Traditionally, the goal of therapy in chronic lymphocytic leukemia (CLL) has been palliative, with first-line therapy using alkylating agents and/or involved field radiotherapy (depending on the stage of disease and sites of involvement) because of the older age of affected patients and the low rate of complete remissions (CRs) with no improvement in overall survival despite treatment. With increasing knowledge about the biology, molecular genetics, and prognostic factors of the disease, the philosophy of care for patients with CLL has evolved from palliation to aiming for a potential cure, especially in younger patients. Furthermore, multiple treatment options have emerged, including purine analogues, monoclonal antibodies, and potentially stem cell transplantation. These have been associated with higher frequencies of CRs and longer durations of responses compared to conventional chemotherapy. In addition, a subset of patients treated with chemoimmunotherapy can achieve durable CRs and molecular remissions. This may translate into improved disease-free survival and potentially a "cure." Because of the heterogeneous nature of CLL, new prognostic markers are currently being incorporated into clinical trials to determine their role in routine clinical practice. This review summarizes current therapeutic regimens that are being evaluated in patients with CLL and management of disease-related complications.

Novel Therapeutic Strategies With Alemtuzumab for Chronic Lymphocytic Leukemia

In the last 10 years purine analogs have become the chemotherapy of choice for the first-line treatment of chronic lymphocytic leukemia, principally because of their superior efficacy compared with alkylating agents. However, many patients experience a relapse after an initial response or become refractory to these agents. The introduction of immunotherapeutic agents has provided renewed hope for fludarabine-refractory patients. Several clinical trials have shown the efficacy of alemtuzumab in patients with fludarabine-refractory chronic lymphocytic leukemia, including those with poor prognostic factors. Current studies indicate that treatment with alemtuzumab can achieve remissions with undetectable residual disease, as assessed by highly sensitive methods such as quantitative polymerase chain reaction or 4-color flow cytometry. These results suggest new applications for alemtuzumab such as combination treatment with chemotherapeutics or immunotherapeutics, maintenance therapy, and in vivo bone marrow purging prior to transplantation. A number of clinical trials are under way assessing the role of alemtuzumab in these settings.

Beyond Detectable Minimal Residual Disease in Chronic Lymphocytic Leukemia

Lymphoproliferative disorders are characterized by the abnormal accumulation of aberrant lymphocytes, which frequently interfere with the processes associated with immunologic response and hematopoiesis. Chronic lymphocytic leukemia (CLL) has traditionally been considered indolent, with a prolonged clinical course. However, a large proportion of patients with CLL have severe symptoms, a poor prognosis, and often require more immediate treatment of their leukemia. Over the last 5 years, technology has transformed the approach to treating patients with CLL. Molecular markers are now available that characterize patients with poor-risk disease who may benefit from earlier or more aggressive therapeutic intervention. Biological markers have also been identified that assist in predicting responses to specific agents and may help select an effective therapeutic approach. The advent of more targeted monoclonal antibody therapies, used in combination with chemotherapy regimens or as monotherapy, has the potential to eradicate disease to a point of undetectability by the most sensitive tests available, thereby possibly extending the goal of therapy to include a cure. Because recent data have shown that achieving minimal residual disease (MRD) in the bone marrow is one of the most important factors in predicting duration of remission, MRD may be an appropriate therapeutic end point for patients with poor-risk CLL. The use of rituximab with the cytotoxic agents cyclophosphamide and fludarabine has achieved complete remission with no detectable CLL, as assessed by MRD techniques in a significant proportion of previously untreated and previously treated CLL patients. Monotherapy with alemtuzumab has also been shown to achieve a complete response with undetectable MRD in patients with relapsed/refractory disease. This article reviews recent advances in identifying patients who have poor-risk disease and explores the potential importance of MRD status as an outcome measure of CLL therapy.

Clinical significance of minimal residual disease, as assessed by different techniques, after stem cell transplantation for chronic lymphocytic leukemia

We analyzed minimal residual disease (MRD) by consensus polymerase chain reaction (PCR), quantitative PCR (qPCR), and flow cytometry in 40 patients with chronic lymphocytic leukemia (CLL) who underwent stem cell transplantation; 97.4%, 89%, and 100% of the patients could be studied by consensus PCR, qPCR, and flow cytometry, respectively. Overall, 164 of 248 samples were negative for MRD by consensus PCR. Among those, CLL cells were detected by qPCR and by flow cytometry in 77 (47%) and 39 (23%) of the 164 samples, respectively. All 84 samples positive on PCR had detectable CLL cells by qPCR and flow cytometry. A good correlation was seen between MRD levels by flow cytometry and by qPCR (n = 254; r = 0.826; P < .001). Fifteen of 25 patients receiving autografts suffered a relapse, with increasing levels of MRD being observed before relapse in all of them. MRD detection within the first 6 months after autologous transplantation identified patients with a high relapse risk. In contrast, in allografted patients (n = 15) MRD did not correlate with outcome. In conclusion, quantitative methods to assess MRD (flow cytometry and qPCR) are more accurate than consensus PCR to predict clinical evolution. These results might be useful to investigate treatments aimed at preventing relapse in patients with CLL who have received an autograft.

The addition of rituximab to fludarabine improves clinical outcome in untreated patients with ZAP-70-negative chronic lymphocytic leukemia

BACKGROUND

Clinical trials of monoclonal antibodies in combination with chemotherapy have reported previously unattained response rates in patients with B-cell chronic lymphocytic leukemia (B-CLL); however, the analysis of ZAP-70 protein and/or CD38 may explain better the discordant outcomes independent of treatment.

METHODS

The authors conducted a Phase II study, in which rituximab was added to fludarabine for patients with symptomatic, untreated CLL, to evaluate clinical outcomes. Sixty patients with B-CLL received 6 monthly courses of fludarabine (25 mg/m(2) for 5 days) followed by 4 weekly doses of rituximab (375 mg/m(2)).

RESULTS

On the basis of National Cancer Institute criteria, 47 of 60 patients (78%) achieved a complete remission, 9 of 60 patients (15%) achieved a partial remission, and 4 of 60 patients (7%) had no response or progressive disease. It is noteworthy that the patients experienced a long progression-free survival (PFS) from treatment (68% at 3 yrs). A significantly shorter PFS was observed in ZAP-70-positive patients (25% vs. 100% at 3 yrs; P = 0.00005), in CD38-positive patients (18% vs. 91% at 3 yrs; P = 0.0002), and in patients who had more minimal residual disease (36% vs. 77% at 2.5 yrs; P = 0.001).

CONCLUSIONS

With the addition of rituximab to fludarabine, improved clinical outcomes were obtained, and the stratification of patients by using ZAP-70 and CD38 may help clinicians offer more aggressive and/or experimental approaches to the treatment of patients with high-risk B-CLL subtypes.

Randomised comparison of two B-cell purging protocols for patients with B-cell non-Hodgkin lymphoma: in vivo purging with rituximab versus ex vivo purging with CliniMACS CD34 cell enrichment device

We investigated the feasibility, safety and efficacy of two B-cell purging methods in patients with CD20+ non-Hodgkin lymphoma (NHL) receiving autologous stsem cell transplantation. Myeloid and immune recoveries between the methods were compared. Twenty-seven patients were randomised to either in vivo purging with rituximab or ex vivo purging by CD34+ cell selection. Both purging methods were efficient at eliminating B-cells in infusates. When compared with in vivo purging, ex vivo purging was associated with CD34+ cell loss and delayed median neutrophil (10 d vs. 11 d) and platelet (12.5 d vs. 17 d) count recoveries. Lymphocyte recovery was similar in both groups, but immunoglobulin recovery was delayed after in vivo purging. Late-infectious complications were few in both arms. At a median follow-up of 27 months, 2-year probabilities of event-free survival (EFS) rates were 81% for in vivo purging and 76% for ex vivo purging (P = 0.66). When compared with 53 unpurged patients, all 27 purged patients had improved 3-year probabilities of overall survival (89% vs. 70%, P = 0.014) and a trend for improved EFS (78% vs. 57%, P = 0.075). In conclusion, although both purging methods were feasible and safe, rituximab purging was superior as it did not impair CD34+ cell mobilisation and was associated with faster myeloid recovery. Further studies are needed to determine whether rituximab purging is more effective than the use of unpurged autografts.

Flow-cytometric immunophenotyping of normal and malignant lymphocytes

During the past two decades, flow-cytometric immunophenotyping of lymphocytes has evolved from a research technique into a routine laboratory diagnostic test. Extensive studies in healthy individuals resulted in detailed age-related reference values for different lymphocyte subpopulations in peripheral blood. This is an important tool for the diagnosis of hematological and immunological disorders. Similar, albeit less detailed, information is now available for other lymphoid organs, e.g., normal bone marrow, lymph nodes, tonsils, thymus and spleen. Flow-cytometric immunophenotyping forms the basis of modern classification of acute and chronic leukemias and is increasingly applied for initial diagnostic work-up of non-Hodgkin's lymphomas. Finally, with multiparameter flow cytometry, it is now possible to identify routinely and reliably low numbers of leukemia and lymphoma cells (minimal residual disease).

Clin Chem Lab Med 2006;44:775–96.

Comparison of mRNA abundance quantified by gene expression profiling and percentage of positive cells using immunophenotyping for diagnostic antigens in acute and chronic leukemias

BACKGROUND

Microarray analysis is considered a future diagnostic tool in leukemias. Whereas data accumulate on specific gene expression patterns in biologically defined leukemia entities, data on the correlation between flow cytometrically determined protein expression, which are essential in the diagnostic setting today, and microarray results are limited.

METHODS

The results obtained by microarray analysis were compared using the Affymetrix GeneChip HG-U133 system in parallel with flow cytometric findings of 36 relevant targets in 814 patients with newly diagnosed acute and chronic leukemias as well as in normal bone marrow samples.

RESULTS

In a total of 21,581 individual comparisons between signal intensities obtained by microarray analysis and percentages of positive cell as determined by flow cytometry, coefficients of correlation in the range of 0.171 to 0.807 were obtained. In particular, the degree of correlation was high in the following genes critical in the diagnostic setting: CD4, CD8, CD13 (ANPEP), CD33, CD23 (FCER2), CD64 (FCGR1A), CD117 (KIT), CD34, MPO, CD20 (MS4A1), CD7 (range of r, 0.589-0.807).

CONCLUSIONS

The present data prove the high degree of correlation between findings obtained by microarray analysis and flow cytometry. They are in favor of a future application of the microarray technology as a robust diagnostic tool in leukemias.

Autologous and allogeneic stem cell transplantations for poor-risk chronic lymphocytic leukemia

We report here on the long-term follow-up on 162 patients with high-risk chronic lymphocytic leukemia (CLL) who have undergone hematopoietic stem cell transplantation (SCT) at a single center from 1989 to 1999. Twenty-five patients with human leukocyte antigen (HLA)-matched sibling donors underwent T-cell-depleted allogeneic SCT, and 137 patients without HLA-matched sibling donors underwent autologous SCT. The 100-day mortality was 4% for both groups, but later morbidity and mortality were negatively affected on outcome. Progression-free survival was significantly longer following autologous than allogeneic SCT, but there was no difference in overall survival and no difference in the cumulative incidence of disease recurrence or deaths without recurrence between the 2 groups. At a median follow-up of 6.5 years there is no evidence of a plateau of progression-free survival. The majority of patients treated with donor lymphocyte infusions after relapse responded, demonstrating a significant graft-versus-leukemia effect in CLL. From these findings we have altered our approach for patients with high-risk CLL and are currently exploring the role of related and unrelated allogeneic SCT following reduced-intensity conditioning regimens.

Immunophenotyping of lymphoproliferative disorders: state of the art

Immunophenotyping was introduced into diagnostic pathology over 30 years ago to assist in the diagnosis and classification of lymphoproliferative disorders. Today the role of immunophenotyping has been expanded beyond this to include the detection of markers of prognosis, determination of disease phenotypes associated with specific chromosomal abnormalities, detection of targets for immunotherapy and to monitor residual disease. Immunoperoxidase detection methods remain the most popular in histopathology, whilst flow cytometry is most commonly applied for haematological samples. The range of monoclonal antibodies available, including those which work in routinely performed tissue specimens, continues to increase. This is in part a result of gene expression studies identifying precise genetic signatures for certain lymphoproliferative disorders and the generation of new protein markers to gene products of upregulated genes. This review summarises the current status and applications of immunophenotyping in the assessment of many of the lymphoid malignancies.

Organisation of neoplastic haematopathology services: a UK perspective

The diagnosis of haematological malignancies has begun to emerge as a distinct pathological discipline in the United Kingdom. This has been driven by the recommendation of the National Institute for Clinical Excellence that diagnosis of leukaemia and lymphoma should take place in a specialist laboratory and in most cases this should be organised on a regional basis. The reason for this guidance was the perception that there was a considerable level of diagnostic inaccuracy and that this could be improved by better integration of the currently available technologies. This is one of a number of major changes in the way that services to patients are being delivered, all of which are centred on the development of multidisciplinary teams responsible for the provision of local services. The introduction of the WHO classification of haematological malignancy provides a structure for the development of integrated haemtopathology laboratories, with its emphasis on definition of disease entities based on clinical, morphological, phenotypical and molecular features. This means that these diagnostic modalities can be used systematically and in parallel to provide effective cross validation of a diagnosis. One of the challenges raised by this approach is the selection of the most informative panels of investigations both at presentation and subsequent follow up from the wide range of options that are now available. The introduction of specialist haematopathology services in the United Kingdom has highlighted a number of scientific and organisational issues that in time may have a wider impact on diagnostic laboratories in general. These include the relationship between size and cost effectiveness and the future role of clinical scientists and medically trained pathologists. Integrated laboratories of the type being developed challenge the prevailing model for delivery of pathological services in the United Kingdom, which is based around the traditional pathology disciplines. These speciality boundaries will become less relevant as long established diagnostic techniques are replaced by the new generation of diagnostic technologies and it is important to establish frameworks of service delivery that can deploy these developments for the benefit of patients.

Allogeneic Transplant with Reduced Intensity Conditioning Regimens may Overcome the Poor Prognosis of B-Cell Chronic Lymphocytic Leukemia with Unmutated Immunoglobulin Variable Heavy-Chain Gene and Chromosomal Abnormalities (11q− and 17p−)

PURPOSE

To evaluate the efficacy of reduced intensity conditioning (RIC) allogeneic transplant in 30 patients with poor-prognosis chronic lymphocytic leukemia (CLL) and/or high-risk molecular/cytogenetic characteristics.

EXPERIMENTAL DESIGN

Eighty-three percent of patients had active disease at the moment of transplant. That is, 14 of the 23 patients analyzed (60%) had unmutated immunoglobulin variable heavy-chain gene (IgV(H)) status; 8 of 25 patients (32%) had 11q-, with four of them also displaying unmutated IgV(H); and six (24%) had 17p- (five were also unmutated).

RESULTS

After a median follow-up of 47.3 months, all 22 patients alive are disease free; overall survival and event-free survival (EFS) at 6 years were 70% and 72%, respectively. According to molecular/cytogenetic characteristics, overall survival and EFS for unmutated CLL and/or with 11q- aberration (n = 13) were 90% and 92%, respectively, not significantly different to those with normal in situ hybridization, 13q- and +12, or mutated CLL (n = 7). All six patients with 17p deletion were transplanted with active disease, including three with refractory disease; all except one reached complete remission after the transplant and two are alive and disease free. Nonrelapse mortality (NRM) was 20%; more than two lines before transplant is an independent prognostic factor for NRM (P = 0,02), EFS (P = 0.02), and overall survival (P = 0.01). Patients older than 55 years have a higher risk of NRM (hazard ratio, 12.8; 95% confidence interval, 1.5-111). Minimal residual disease was monitored by multiparametric flow cytometry in 21 patients. Clearance of CD79/CD5/CD19/CD23 cells in bone marrow was achieved in 68% and 94% of the patients at days 100 and 360, respectively.

CONCLUSION

According to these results, RIC allogeneic transplant could overcome the adverse prognosis of patients with unmutated CLL as well as those with 11q- or 17p-.

Fludarabine in Combination With Alemtuzumab Is Effective and Feasible in Patients With Relapsed or Refractory B-Cell Chronic Lymphocytic Leukemia: Results of a Phase II Trial

Purpose

To determine the efficacy and safety of a newly developed concomitant administration of fludarabine and alemtuzumab (FluCam) in patients with relapsed or refractory B-cell chronic lymphocytic leukemia (B-CLL).

Patients and Methods

A total of 36 patients were treated in this phase II study (median age, 61.47 years; mean number of prior chemotherapies, 2.6; Binet stage C, n = 28). After an initial dose escalation of alemtuzumab over 3 days, alemtuzumab 30 mg and fludarabine 30 mg/m2 were administered on 3 consecutive days. Treatment was repeated after 28 days for up to six cycles. Restaging (following National Cancer Institute criteria) was carried out after cycles 2 and 4 and 1 month after the end of treatment.

Results

The overall response rate was 83% (11 complete responses, 19 partial responses, one stable disease, and five progressive diseases). Two patients with progressive disease developed fungal pneumonias, and one patient died as a result of Escherichia coli sepsis. Two subclinical cytomegalovirus reactivations occurred.

Conclusion

The new FluCam regimen is effective and feasible in patients with relapsed and refractory B-CLL.

Diagnostic criteria for monoclonal B-cell lymphocytosis

Very low levels of circulating monoclonal B-cell subpopulations can now be detected in apparently healthy individuals using flow cytometry. We propose the term 'monoclonal B-cell lymphocytosis' (MBL) to describe this finding. The aim of this document is to provide a working definition of MBL for future clinical, epidemiological and laboratory studies. We propose that the detection of a monoclonal B-cell population by light chain restriction is sufficient to define this condition in individuals not meeting the diagnostic criteria for other B-lymphoproliferative disorders. The majority of individuals with MBL will have cells that are indistinguishable from chronic lymphocytic leukaemia (CLL). However, this blood cell clonal expansion of CD5+ or CD5- B-lymphocytes is age-dependent and immunophenotypic heterogeneity is common. Longitudinal studies are required to determine whether MBL is a precursor state to CLL or other B-lymphoproliferative disease in a situation analogous to a monoclonal gammopathy of undetermined significance and myeloma. Future studies of MBL should be directed towards determining its relationship to clinical disease, particularly in individuals from families with a genetic predisposition to developing CLL.

The Emerging Role of Alemtuzumab in Chronic Lymphocytic Leukemia

Targeted therapy for malignant hematologic disorders has become a realistic goal with the identification of novel antibodies that are designed to act against highly expressed antigens on malignant clones. CD52 is abundantly expressed on malignant lymphocytes in chronic lymphocytic leukemia (CLL). Alemtuzumab is a humanized monoclonal antibody that targets CD52 and induces cell death by several mechanisms that are still under investigation. The initial positive results of many clinical studies that explored the activity of alemtuzumab in relapsed and/or refractory CLL have provoked many oncologists to incorporate this agent into the treatment paradigm of this disease. Prophylactic antibiotics for the duration of therapy or until patients are no longer immunocompromised are recommended. This review summarizes the clinical experience with alemtuzumab that eventually led to its approval. Recent novel prognostic factors and trends in CLL therapy are also reviewed.

Early results of a chemoimmunotherapy regimen of fludarabine, cyclophosphamide, and rituximab as initial therapy for chronic lymphocytic leukemia

PURPOSE

Fludarabine and cyclophosphamide (FC), which are active in treatment of chronic lymphocytic leukemia (CLL), are synergistic with the monoclonal antibody rituximab in vitro in lymphoma cell lines. A chemoimmunotherapy program consisting of fludarabine, cyclophosphamide, and rituximab (FCR) was developed with the goal of increasing the complete remission (CR) rate in previously untreated CLL patients to >/= 50%.

PATIENTS AND METHODS

We conducted a single-arm study of FCR as initial therapy in 224 patients with progressive or advanced CLL. Flow cytometry was used to measure residual disease. Results and safety were compared with a previous regimen using FC.

RESULTS

The median age was 58 years; 75 patients (33%) had Rai stage III to IV disease. The CR rate was 70% (95% CI, 63% to 76%), the nodular partial remission rate was 10%, and the partial remission rate was 15%, for an overall response rate of 95% (95% CI, 92% to 98%). Two thirds of patients evaluated with flow cytometry had less than 1% CD5- and CD19-coexpressing cells in bone marrow after therapy. Grade 3 to 4 neutropenia occurred during 52% of courses; major and minor infections were seen in 2.6% and 10% of courses, respectively. One third of the 224 patients had >/= one episode of infection, and 10% had a fever of unknown origin.

CONCLUSION

FCR produced a high CR rate in previously untreated CLL. Most patients had no detectable disease on flow cytometry at the end of therapy. Time to treatment failure analysis showed that 69% of patients were projected to be failure free at 4 years (95% CI, 57% to 81%).

Eradication of minimal residual disease in B-cell chronic lymphocytic leukemia after alemtuzumab therapy is associated with prolonged survival

PURPOSE

To test whether eradication of minimal residual disease (MRD) in B-cell chronic lymphocytic leukemia (CLL) by alemtuzumab is associated with a prolongation of treatment-free and overall survival.

PATIENTS AND METHODS

Ninety-one previously treated patients with CLL (74 men and 17 women; median age, 58 years [range, 32 to 75 years]; 44 were refractory to purine analogs) received a median of 9 weeks of alemtuzumab treatment between 1996 and 2003. Regular bone marrow assessments by MRD flow cytometry were performed with the aim of eradicating detectable MRD (< 1 CLL cell in 10(5) normal cells).

RESULTS

Responses according to National Cancer Institute-sponsored working group response criteria were complete remission (CR) in 32 patients (36%), partial remission (PR) in 17 patients (19%), and no response (NR) in 42 patients (46%). Twenty-two (50%) of 44 purine analog-refractory patients responded to alemtuzumab. Detectable CLL was eradicated from the blood and marrow in 18 patients (20%). Median survival was significantly longer in MRD-negative patients compared with those achieving an MRD-positive CR, PR, or NR. Patients achieving an MRD-negative CR had a longer treatment-free survival than patients with MRD-positive CRs, PR, or NR: MRD-negative CRs, not reached; MRD-positive CRs, 20 months; PRs, 13 months; NR, 6 months (P < .0001). Overall survival for the 18 patients with MRD-negative remissions was 84% at 60 months. Eight (47%) of the MRD-negative patients converted to MRD positivity at a median of 28 months.

CONCLUSION

MRD-negative remission in CLL is achievable with alemtuzumab, leading to an improved overall and treatment-free survival.

Chronic lymphocytic leukemia: A review of some new aspects of the biology, factors influencing prognosis and therapeutic options

This review provides some basic information on chronic lymphocytic leukemia (CLL) and attempts to present some of the newer data which have accumulated in recent years including those relating to familial aggregation of CLL and the detection of monoclonal CD5+ lymphocytosis in the general population and families of CLL patients. Novel data on the pathogenesis and concepts of cell origin in CLL are also reviewed stressing the fact that there is biased IgVH gene usage, and the importance of mutational status of the CLL cell, as reported in recent years by different authors. A brief review of the significance of the microenvironmental interactions between stromal cells and other accessory cells, and the leukemic CLL cells is also provided. Other clinical aspects are discussed including diagnostic criteria, clinical staging, and the newer prognostic factors which influence survival and timing of therapy for CLL patients. We also attempt to outline the therapeutic options available and the principles of planning risk and age-adapted treatment, stressing the importance and the necessity for participating in ongoing and future international clinical trials.

Clonal lymphocytes in persons without known chronic lymphocytic leukemia (CLL): implications of recent findings in family members of CLL patients

Several genetic abnormalities have been characterized in chronic lymphocytic leukemia (CLL) but these are predominantly secondary events and the initiating phenomena in the etiology of the disease are yet to be established. Studies of inherited susceptibility have identified the early oncogenic events in both familial and "sporadic" forms of several malignant disorders, and this may also be possible in CLL. However, the utility of linkage analysis in identifying a predisposition locus for the disease is limited because large multigenerational families segregating CLL are rare, while the more frequent small nuclear CLL families contain insufficient numbers of affected individuals. The power to detect predisposition gene(s) could be greatly increased by extending the number of affected individuals within a particular family, for example, by identifying family members with subclinical levels of disease. High-sensitivity flow cytometry techniques, developed to monitor disease in CLL patients undergoing treatment, have allowed accurate enumeration of subclinical levels of CLL cells in healthy individuals from the general population and CLL families. Emerging evidence confirms the phenotypic, genotypic, and clinical associations between the aberrant cells in healthy individuals and those in CLL patients. The data suggest that inherited factors increase the susceptibility to both indolent and aggressive CLL, and they provide unbiased demonstration that the age of onset in CLL families is younger than in the general population.

Alemtuzumab in the Treatment of Chronic Lymphocytic Leukemia

Alemtuzumab is a humanized therapeutic monoclonal antibody (MAb) that recognizes the CD52 antigen, expressed on normal and neoplastic lymphocytes, monocytes, and natural killer cells. In 2001, alemtuzumab was approved in the US and Europe to treat B-cell chronic lymphocytic leukemia (CLL) that had been treated previously with alkylating agents and was refractory to fludarabine. In heavily pretreated patients this MAb is able to produce response rates of about 40%, and in symptomatic, previously untreated patients response rates of more than 80% can be achieved. Alemtuzumab can also be used in patients with CLL as a preparative regimen for stem cell transplantation (SCT) and to prevent graft versus host disease. Moreover its in vivo use before or after SCT may also potentially result in depletion of residual leukemia cells, especially in the autologous setting. Adverse events associated with alemtuzumab include acute first-dose reaction, hematologic toxicity, and infectious complications. Usually they are predictable, manageable, and acceptable in the context of CLL. However, in a significant percentage of patients, cytomegalovirus reactivation occurs during alemtuzumab therapy, and routine weekly monitoring with the polymerase chain reaction methodology is indicated. Moreover, antiviral and antibacterial prophylaxis is mandatory.

Comparative analysis of minimal residual disease detection using four-color flow cytometry, consensus IgH-PCR, and quantitative IgH PCR in CLL after allogeneic and autologous stem cell transplantation

The clinically most suitable method for minimal residual disease (MRD) detection in chronic lymphocytic leukemia is still controversial. We prospectively compared MRD assessment in 158 blood samples of 74 patients with CLL after stem cell transplantation (SCT) using four-color flow cytometry (MRD flow) in parallel with consensus IgH-PCR and ASO IgH real-time PCR (ASO IgH RQ-PCR). In 25 out of 106 samples (23.6%) with a polyclonal consensus IgH-PCR pattern, MRD flow still detected CLL cells, proving higher sensitivity of flow cytometry over PCR-genescanning with consensus IgH-primers. Of 92 samples, 14 (15.2%) analyzed in parallel by MRD flow and by ASO IgH RQ-PCR were negative by our flow cytometric assay but positive by PCR, thus demonstrating superior sensitivity of RQ-PCR with ASO primers. Quantitative MRD levels measured by both methods correlated well (r=0.93). MRD detection by flow and ASO IgH RQ-PCR were equally suitable to monitor MRD kinetics after allogeneic SCT, but the PCR method detected impending relapses after autologous SCT earlier. An analysis of factors that influence sensitivity and specificity of flow cytometry for MRD detection allowed to devise further improvements of this technique.

Current guidelines in defining therapeutic strategies

The past three decades have brought major changes in the approach toward chronic lymphocytic leukemia (CLL). This disease was considered a simple form of leukemia for which the only goal of treatment was control of the leukocytosis and of the symptoms related to disease expansion. Many biologic discoveries have increased our understanding of the disease process. New prognostic markers have been identified and are being incorporated into clinical practice. Now, CLL is considered a complex and challenging leukemia for which multiple treatment options are emerging, from chemotherapy to monoclonal antibodies, from vaccines to immunomodulatory strategies. The evaluation of treatment results also has been revolutionized: clones carrying genetic aberrations are monitored, and patients who have had a response are assessed for the presence of minimal residual disease.

Role of auto- and allotransplantation in B-cell chronic lymphocytic leukemia

Although important progress has been made in its management, B-cell chronic lymphocytic leukemia (CLL) remains incurable with standard therapies. Hematopoietic stem-cell transplants (HSCT) are frequently being offered to individuals with CLL, the hope being that, as in other hematologic malignancies, they can prolong survival in or even cure some patients. This article analyzes which patients with CLL are appropriate candidates for HSCT, current transplant procedures, results with autologous and allogeneic HSCT, and future trends in transplantation in this form of leukemia.