Adverse prognostic significance of CD20 expression in adults with Philadelphia chromosome-negative B-cell precursor acute lymphoblastic leukemia

Role of allogeneic hematopoietic stem cell transplantation in adult patients with acute lymphoblastic leukemia

Adult acute lymphoblastic leukemia (ALL) is a heterogeneous disease, due to the expression of different biological and clinical risk factors, for which allogeneic stem cell transplantation (alloHSCT) is an effective consolidation therapy. The non-relapse mortality of alloHSCT remains significantly higher compared with that of conventional chemotherapy. Therefore, one of the main challenges in the care of ALL is to establish a more precise prognostic definition to select patients who could take advantage from an alloHSCT. Currently, the use of minimal residual disease following induction and early consolidation therapy has improved the prognostic accuracy in defining ALL risk class. In Philadelphia-positive ALL, the introduction of tyrosine kinase inhibitors pre and post alloHSCT appears to improve outcomes significantly and, in the absence of specially designed clinical trials, alloHSCT remains the most effective post-remission therapy. Nowadays, alloHSCT can be performed according to various modalities encompassing the use of different conditioning regimens, as well as distinct donors and stem cell source, with a significant accessibility to transplant.

High levels of CD20 expression predict good prognosis in chronic lymphocytic leukemia

Heterogeneity of CD20 expression exists in chronic lymphocytic leukemia (CLL), therefore, we explored the prognostic significance of CD20 expression in Chinese patients with CLL. Multiparameter flow cytometry was used to detect the expression of CD20 in CD5(+) CD19(+) cells. In 172 CLL patients, the median expression percent of CD20 was 97.82% (range, 0-100), and the median mean fluorescence intensity (MFI) of CD20 in CLL cells was 731.45 (range, 0.00-9071.90). The percentage of CD20(+) cells in the patient group with mutated variable region of immunoglobulin genes (IGHV) was higher than in the non-mutant IGHV group (mean, 92.1% vs 80.4%, P < 0.001). There were no differences in the MFI of CD20(+) cells in all prognostic factor groups. Representation of the data using a receiver operating characteristic plot reflected separation between the two IGHV groups, with an area under the curve of 0.661 (95% confidence interval, 0.569-0.753). At the cut-off value of 60.3% for percentage of CD20, the sensitivity and specificity were 90.00% and 38.46%, respectively. Patients whose percentage of CD20 antigen was above 60.3% had longer treatment-free survival (hazard ratio, 0.452; 95% confidence interval, 0.232-0.884, P = 0.020). Percentage and MFI of CD20 were the variables not associated with treatment-free survival by multivariate Cox regression analysis (P < 0.05). High level of CD20 expression in de novo CLL appears to be associated with a good prognosis.

Novel therapeutic strategies in adult acute lymphoblastic leukemia--a focus on emerging monoclonal antibodies

The outcomes in adult B-cell acute lymphoblastic leukemia (ALL) remain inferior to those achieved in pediatric populations. Targeted therapy with monoclonal antibodies may improve outcomes in adult B-cell ALL without significant additive toxicity. Rituximab is the best known monoclonal antibody and is routinely used in combination chemo-immunotherapy for treatment of adult B-cell ALL and Burkitts leukemia. A number of other monoclonal antibodies are currently under investigation for treatment of adult B-cell ALL including unconjugated antibodies (eg., ofatumumab, alemtuzumab and epratuzumab), antibodies conjugated to cytotoxic agents (eg., inotuzumab ozogamycin and SAR3419), antibodies conjugated to toxins such Pseudomonas or Diptheria toxins (eg., BL22 and moxetumomab pasudotox), and T-cell engaging bi-specific antibodies that redirect cytotoxic T lymphocytes to lyse target ALL cells (eg., blinatumomab). In this article we review the therapeutic implications, current status and results of monoclonal antibody-based therapy in adult B-cell ALL.

New immune strategies for the treatment of acute lymphoblastic leukemia: antibodies and chimeric antigen receptors

The prognosis of adult acute lymphoblastic leukemia (ALL) remains poor and novel treatment strategies are needed. Antibody-based therapies represent such an approach. ALL cells express various surface antigens that are targets for monoclonal antibodies. This review focuses on 4 major classes of antibody therapy: (1) naked antibodies, (2) T-cell-engaging bispecific single-chain antibodies, (3) immunoconjugates/immunotoxins, and (4) chimeric antigen receptors. Preclinical and clinical data are reviewed. This area of research represents an exciting new approach to help improve the outcome of this disease. Several clinical trials are currently incorporating this therapy in the treatment of newly diagnosed and relapsed adult ALL patients.

Expression of CD20 in B Cell Precursor Acute Lymphoblastic Leukemia

CD20 is a B cell differentiation antigen with variable expression in B cell precursor acute lymphoblastic leukemia (BCP-ALL). The significance of CD20 expression has been evaluated in BCP-ALL with conflicting results. There is paucity of data regarding CD 20 expression in BCP-ALL in Indian patients. We retrospectively analyzed 100 patients of BCP-ALL for CD20 expression. CD20 positivity was defined as expression of CD20 to be more than or equal to 20 % in the blast population. 62 % patients expressed CD20 while 38 % patients were negative for CD20. The positivity ranged from negative to dim (35.5 % patients), moderately bright (19.3 % patients) to bright (45.2 % patients). Additional prospective studies are needed to determine the optimal use of rituximab in treatment of CD20-positive BCP-ALL.

What is the impact, present and future, of novel targeted agents in acute lymphoblastic leukemia?

The absence of a standard of care for adults with acute lymphoblastic leukemia (ALL), the inadequate outcome of all adult regimens, and the lack of improvement in treatment outcomes over the past decades suggest a critical need for new approaches to treating adults with this disease. Several new strategies are now being considered, including the use of novel targeted agents alone and in combination with other chemotherapeutic drugs. This paper discusses several of these approaches and their impact on overall outcome.

Prognostic factors in adult acute leukemia

The prognostic factors in acute leukemia have undergone a major change over the past decade and are likely to be further refined in the coming years. While age is the single most important prognostic factor in both AML and in ALL, recurring cytogenetic abnormalities and molecular markers have become crucial for the prognosis of patients and for new directions in the development of targeted therapies. No less important is the development of a personalized approach for therapy as determined by the response to therapy using increasingly sensitive technologies. The assessment of MRD is rapidly superseding other prognostic factors in ALL and, somewhat lacking behind, coming into its own in AML. The next decade should see further refinement of response-driven prognostication, to include epigenetics as well as pharmacogenetics and pharmacodynamics of individual drugs used and the responses to them. It is hoped that these refinements and better predictors of response will also lead to a significantly improved overall outcome of patients with both AML and ALL.

Novel therapeutic approaches for acute lymphoblastic leukemia

Therapy for ALL in adults remains a tremendous challenge for clinicians. The use of pediatric-intensive regimens in young and middle-aged adults shows promise in improving outcomes. The addition of monoclonal antibody therapy to chemotherapy appears to hold great promise in lessening relapse rates. The anti-CD20 antibody, rituximab, which has been of such benefit in patients with non-Hodgkin lymphoma, now seems poised to bring significant benefit to adults with ALL. Other monoclonal antibody approaches are in earlier stages of development, but will likely be of significant benefit. The BiTE antibody, blinatumomab, represents an exciting new approach in this arena. As new molecular abnormalities are identified in ALL, these will certainly become new targets for drug development. The increasing use of MRD testing by molecular or flow cytometric techniques will also be invaluable in further refining prognostication in ALL in helping with the selection of patients most likely to benefit from BMT. Several new small molecules and chemotherapeutic agents will, it is hoped, also find a niche in the therapy for ALL. Early examples including NOTCH1 inhibitors; hypomethylating agents such as decitabine, folic acid, antagonists, flavopiridol, bortezomib, and mTOR inhibitors will all hopefully find a role in the therapy for this challenging disorder. Although many challenges remain, there is hope that the therapy for adults with ALL can make significant progress in the next few years, in comparison with the relative plateau that has been experienced over the last several decades.

Allogeneic hematopoietic cell transplantation for acute lymphoblastic leukemia in adults

PURPOSE OF REVIEW

Acute lymphoblastic leukemia (ALL) is a heterogeneous disease, for which treatment guidelines are still evolving. Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative therapeutic modality for ALL, and this review describes the recent studies and current practice patterns concerning the who, when, and how of allo-HCT in the management of ALL.

RECENT FINDINGS

Allogeneic stem cell transplantation is the treatment of choice for patients with ALL after first relapse and is also recommended for high-risk patients in first complete remission (CR1). Minimal residual disease evaluation and monitoring is developing as an important prognostic factor and could guide physicians in determining which patients, especially those with standard risk, might require transplant. Tyrosine kinase inhibitor (TKI) therapy allows a much higher proportion of Philadelphia-chromosome-positive ALL patients to attain remission and proceed to transplant with improved results; posttransplant TKI maintenance therapy may also provide survival benefit. Reduced-intensity conditioning regimens are a reasonable alternative for patients who would otherwise be ineligible for transplant because of age or comorbidity.

SUMMARY

For patients with high-risk features, there is general agreement that allo-HCT in CR1 is a potentially curative option; however, there is no consensus on early transplant for standard-risk patients.

Emerging pharmacotherapies for adult patients with acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) treatment regimes are amongst the longest, most intensive and complex used in hematooncology. Despite this, while treatment of pediatric ALL is a success story, we are far from being able to ensure a durable response in adult ALL. This is not due to failure of induction therapy as a complete remission (CR) is achieved in over 90% of patients. However the challenge remains in ensuring a sustained remission. Furthermore in the face of relapsed disease, salvage therapies currently offer a poor chance of a good outcome. This article reviews the novel agents which show the most promise in the treatment of adult ALL.

Advances in acute lymphoblastic leukemia in adults

PURPOSE OF REVIEW

This review will be focused on the advances in adult acute lymphoblastic leukemia (ALL) based on recently published articles.

RECENT FINDINGS

Progress in the understanding of the molecular basis of ALL has contributed to a more precise definition of risk factors. The study of minimal residual disease has re-defined the baseline prognostic factors and has opened new strategies for postremission management. The use of pediatric-inspired therapies for young adults with standard-risk ALL, the broadening of the number of patients who are eligible for allogeneic stem cell transplantation, the increasing use of targeted therapies (monoclonal antibodies, tyrosine kinase inhibitors, and new purine analogs, etc.) in early phases of the disease, together with the improvements in supportive therapy explain the increased survival of young and middle-aged adult ALL.

SUMMARY

These changes are improving long-term outcome, which in ongoing studies is expected to be of close to 50%, and are opening the door for future therapeutic advances.

CD20 expression has no prognostic role in Philadelphia-negative B-precursor acute lymphoblastic leukemia: new insights from the molecular study of minimal residual disease

The prognostic significance of CD20 expression in acute lymphoblastic leukemia has been investigated in children and adults but is still a subject of debate. The aim of our study was to correlate CD20 expression with clinical-biological characteristics and outcome in 172 Philadelphia chromosome negative patients prospectively treated in a multicenter trial introducing the molecular evaluation of minimal residual disease for therapeutic purposes. We considered 20% as the threshold for CD20 positivity. Complete remission rate, minimal residual disease negativity rate at weeks 10, 16 and 22, and disease-free and overall survival were similar among CD20-positive and -negative patients, even considering minimal residual disease results and related therapeutic choices. Our study failed to demonstrate any prognostic significance for CD20 expression in Philadelphia chromosome negative acute lymphoblastic leukemia. This conclusion is supported for the first time by a comparable minimal residual disease response rate among CD20-positive and -negative and positive patients.

Chemoimmunotherapy in acute lymphoblastic leukemia

ALL blast cells express a variety of specific antigens e.g. CD19, CD20, CD22, CD33, and CD52, which serve as targets for Monoclonal Antibodies (MoAbs). So far, the most experience is available for anti-CD20 (rituximab), which has been combined with chemotherapy for treatment of mature B-ALL/Burkitt's lymphoma. Studies with rituximab have also been completed in B-precursor ALL. Another antigen, CD19, is of great interest due to a very high rate of expression in ALL. It can be targeted by a bispecific monoclonal antibody, Blinatumomab, directed against CD19 and CD3. Smaller studies or case reports are also available for the anti CD52 antibody (Alemtuzumab), for anti CD22 (Epratuzumab) or anti CD33 (Gemtuzumab). Available data demonstrate that MoAb therapy in ALL is a highly promising targeted treatment. However, several details for an optimal treatment approach e.g. the required level of antigen expression, timing, schedule, dosage and stage of disease still need to be defined.

Pharmacotherapeutic advances in the treatment of acute lymphoblastic leukaemia in adults

Acute lymphoblastic leukaemia (ALL) in adults is a challenging malignancy in that many patients will show evidence of initial chemotherapy responsiveness but will subsequently relapse. The disease is heterogeneous and outcomes vary dramatically depending on the prognostic factors present in an individual patient. An important determinant of outcome is the age of the patient. The stunning success of therapy in paediatric ALL has led to the use of intensive paediatric regimens in adolescents and young adults with what appear to be improved outcomes. For patients who relapse or have high-risk features, blood and marrow transplantation (BMT) continues to play an important role in the therapeutic armamentarium. The use of reduced-intensity conditioning regimens for allogeneic BMT suggests that outcomes may be improved by this approach. Monoclonal antibodies are showing benefit as single agents in the relapsed setting or in combination with chemotherapy in newly diagnosed patients. In recent years, several new chemotherapeutic agents have shown promise as single agents and are being incorporated into multi-agent chemotherapy. The development of tyrosine kinase inhibitors for Philadelphia chromosome-positive leukaemias has significantly improved outcomes. The molecular revolution has led to the identification of new aberrant molecular pathways in the pathogenesis of ALL, and drugs targeting these aberrancies are in various stages of development preclinically and clinically. These developments bring the hope that therapeutic outcomes in adult ALL can begin to approach those seen in the paediatric setting.

Allogeneic hematopoietic stem cell transplantation overcomes the adverse prognostic impact of CD20 expression in acute lymphoblastic leukemia

CD20 expression is associated with early recurrence and inferior survival in precursor-B acute lymphoblastic leukemia patients treated with chemotherapy. Whether CD20 influences outcomes after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is unknown. We analyzed CD20 expression on blasts at diagnosis in 157 patients who underwent allo-HSCT in the first complete remission (57%) or the second complete remission (43%). Of 125 evaluable patients, 71 were ≥ 20 years of age. CD20 expression was observed in 58 patients (46%; 52% of children, 39% of adults). There was no association between age, Ph(+) status, white blood cell count at diagnosis, and CD20 positivity. After allo-HSCT, disease-free survival at 5 years was 48% for all patients, 55% (95% confidence interval 40%-67%) for CD20(+) patients, and 43% (95% confidence interval 30%-54%) for CD20(-) patients (P = .15). Relapse did not differ between the groups. These results can serve as a reference to evaluate incorporation of anti-CD20 therapeutics to HSCT for the CD20(+) acute lymphoblastic leukemia subset. Clinical trial numbers for www.clinicaltrials.gov are NCT00365287, NCT00305682, and NCT00303719.

Prognostic significance of immunophenotypic and karyotypic features of Philadelphia positive B-lymphoblastic leukemia in the era of tyrosine kinase inhibitors

BACKGROUND

Philadelphia chromosome (Ph)-positive B-lymphoblastic leukemia exhibits immunophenotypic, karyotypic, and molecular genetic heterogeneity. The prognostic significance of these parameters was assessed in the context of intensive tyrosine kinase inhibitor (TKI)-based chemotherapy.

METHODS

The authors studied 65 adult patients with Ph-positive acute lymphoblastic leukemia (ALL) who received treatment with TKI-based therapy, correlated their clinicopathologic heterogeneity with patient outcome, and compared the findings with those from 60 adult patients with diploid B-cell ALL who received similar chemotherapy without a TKI.

RESULTS

Ph-positive ALL was associated with older age (P = .01), the common-B immunophenotype characterized by a greater frequency of CD13 (alanine aminopeptidase) coexpression (P = .004), CD66c (carcinoembryonic antigen-related cell adhesion molecule 3) expression (P = .007), and CD25 (interleukin-2 receptor alpha chain) expression (P < .001) and with a lower frequency of CD15 (3-fucosyl-N-acetyl-lactosamine) expression (P < .001). Conventional karyotypic analyses indicated that the Ph chromosome was the sole abnormality in 19 patients (30%), was present with other aberrancies in 43 patients (65%), and was absent (detectable only by fluorescence in situ hybridization [FISH] or quantitative reverse transcriptase-polymerase chain reaction [RT-PCR] analysis) in 3 patients (5%). The presence of the breakpoint cluster region-v-Abelson murine leukemia viral oncogene homolog fusion gene (BCR-ABL) was confirmed in all patients by FISH or RT-PCR (the 190-kDa protein [p190] construct was present in 49 patients [77%], and the p210 fusion transcript construct was present in 15 patients [23%]). The presence of a supernumerary Ph chromosome was correlated with a higher incidence of CD20 (B-lymphocyte antigen, nonglycosylated phosphoprotein) expression (P < .001), whereas the p210 construct was correlated with aberrant CD25 expression (P = .05). Outcomes were not influenced by the degree of karyotypic complexity (including the presence or absence of a supernumerary Ph chromosome), CD20 expression, or myeloid antigen expression (CD13, CD33 [myeloid lineage transmembrane receptor], CD66c). CD25 expression was associated with inferior survival in univariate analysis (P = .051) but not in multivariate analysis (P = .092).

CONCLUSIONS

In the context of intensive, TKI-based chemotherapy, the immunophenotypic, karyotypic, and molecular heterogeneity of Ph-positive ALL no longer influences outcome.

Novel antibody-based therapies for acute lymphoblastic leukemia

A major breakthrough in the treatment of acute lymphoblastic leukemia (ALL) was the availability of targeted therapies targeting either specific transcripts, such as bcr-abl fusion protein by tyrosine kinase inhibitors (TKIs), or specific antigens by mAbs. ALL blast cells express a variety of specific antigens (eg, CD19, CD20, CD22, CD33, and CD52) that serve as targets for mAbs. To date, the most data are available for anti-CD20 (rituximab), which has been combined with chemotherapy for the treatment of mature B-ALL/Burkitt lymphoma. Studies with rituximab have also been completed in B-precursor ALL. Another antigen, CD19, is of great interest due to a very high rate of expression in ALL. It can be targeted by a bispecific mAb, blinatumomab, directed against CD19 and CD3. Smaller studies or case reports are also available for the anti-CD52 (alemtuzumab), anti-CD22 (epratuzumab), and anti-CD33 (gemtuzumab) mAbs. Available data demonstrate that mAb therapy in ALL is a highly promising treatment approach. However, several details for an optimal treatment approach, such as the required level of antigen expression, timing, schedule, dosage, and stage of disease, still need to be defined.

The Role of Monoclonal Antibodies in the Management of Leukemia

This article will review the monoclonal antibodies more commonly used in leukemias. In the last three decades, scientists have made considerable progress understanding the structure and the functions of various surface antigens, such as CD20, CD33. The introduction of rituximab, an anti CD20 monoclonal antibody, had a great impact in the treatment of lymphoproliferative disorders. Gemtuzumab, an anti CD 33 conjugated monoclonal antibody has activity in acute mylegenous leukemia (AML). As this field is undergoing a rapid growth, the years will see an increasing use of monoclonal antibodies in hematological malignancies.

Chemoimmunotherapy with a modified hyper-CVAD and rituximab regimen improves outcome in de novo Philadelphia chromosome-negative precursor B-lineage acute lymphoblastic leukemia

PURPOSE

The adverse prognosis of CD20 expression in adults with de novo precursor B-lineage acute lymphoblastic leukemia (ALL) prompted incorporation of monoclonal antibody therapy with rituximab into the intensive chemotherapy regimen hyper-CVAD (fractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone). Other modifications (irrespective of CD20 expression) included early anthracycline intensification, alterations in number of risk-adapted intrathecal chemotherapy treatments for CNS prophylaxis, additional early and late intensifications, and extension of maintenance phase chemotherapy by 6 months.

PATIENTS AND METHODS

Two hundred eighty-two adolescents and adults with de novo Philadelphia chromosome (Ph)-negative precursor B-lineage ALL were treated with standard or modified hyper-CVAD regimens. The latter incorporated standard-dose rituximab if CD20 expression > or = 20%.

RESULTS

The complete remission (CR) rate was 95% with 3-year rates of CR duration (CRD) and survival (OS) of 60% and 50%, respectively. In the younger (age < 60 years) CD20-positive subset, rates of CRD and OS were superior with the modified hyper-CVAD and rituximab regimens compared with standard hyper-CVAD (70% v 38%; P < .001% and 75% v 47%, P = .003). In contrast, rates of CRD and OS for CD20-negative counterparts treated with modified versus standard hyper-CVAD regimens were similar (72% v 68%, P = not significant [NS] and 64% v 65%, P = NS, respectively). Older patients with CD20-positive ALL did not benefit from rituximab-based chemoimmunotherapy (rates of CRD 45% v 50%, P = NS and OS 28% v 32%, P = NS, respectively), related in part to deaths in CR.

CONCLUSION

The incorporation of rituximab into the hyper-CVAD regimen appears to improve outcome for younger patients with CD20-positive Ph-negative precursor B-lineage ALL.

Prognostic factors in adult acute lymphoblastic leukaemia

Treatment of acute lymphoblastic leukaemia (ALL) in adults presents a formidable challenge. While overall results have improved over the past 3 decades, the long-term survival for patients aged less than 60 years is only in the range of 30-40% and is 10-15% if between 60 and 70 years and <5% for those over 70 years. The historic lack of clear-cut biological prognostic factors has led to over- or under-treatment of some patients. Response to initial therapy is an important prognosticator of outcome based on disease biology, as well as pharmacogenetics, which include the patient's response to drugs given. The more widespread availability of allogeneic transplantation and reduced-intensity regimens for older patients have opened up this curative modality to a greater number of patients. Hopefully, those options, as well as novel cytogenetic and molecular markers, will enable a better selection of patients who undergo intensive therapies and finally break the 30-40% cure barrier for adults with ALL.

Treating the "older" adult with acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) in adults is a rare disease. The results of therapy remain unsatisfactory, and progress has been relatively slow. This article will focus on curative therapy in patients aged 30 to 60 years, but will also discuss the management of elderly patients with ALL. Recent large trials have increased our knowledge of the factors that determine outcome, and have clarified the role of blood and marrow transplantation in the management of this disease. These trials have also highlighted the major issues we need to focus on if we are to improve outcomes. This article describes the results of chemotherapy and blood and marrow transplantation for Philadelphia chromosome negative and positive adult ALL in the "older" adult patient, but also critically examines the major controversies and suggests how they might be resolved. The role of allografting in adult ALL is comprehensively discussed. Results of recent studies on T-cell ALL and reduced-intensity allografting are reviewed. A better understanding of the biology of the disease (including gene profiling) may allow individualization of therapy and, in time, targeted therapy.