Results of first salvage therapy for patients refractory to a fludarabine regimen in chronic lymphocytic leukemia

Ofatumumab is active in patients with fludarabine-refractory CLL irrespective of prior rituximab: results from the phase 2 international study

Ofatumumab, the human CD20 monoclonal antibody that binds a distinct epitope from rituximab, has demonstrated clinical benefit as monotherapy for patients with chronic lymphocytic leukemia refractory to fludarabine and alemtuzumab (FA-ref) and patients refractory to fludarabine with bulky (> 5 cm) lymph nodes (BF-ref). To potentially gain insight into outcomes in patients previously treated with or refractory to rituximab, we performed an ad hoc retrospective analysis in the final 96 FA-ref and 111 BF-ref patients. There were 117 patients previously treated with rituximab (98 rituximab-refractory); 89 patients were rituximab-naive. For rituximab-treated, rituximab-refractory, and rituximab-naive patients, overall response rate was 43%, 44%, and 53%; median progression-free survival was 5.3, 5.5, and 5.6 months; and median overall survival was 15.5, 15.5, and 20.2 months. There were no significant differences in ofatumumab-related infusion reactions, or hematologic or infectious adverse events between subgroups. In summary, ofatumumab monotherapy was effective and well tolerated in patients with fludarabine-refractory chronic lymphocytic leukemia, including in patients with previous rituximab exposure. This trial was registered at www.clinicaltrials.gov as #NCT00349349.

Bendamustine combined with rituximab in patients with relapsed and/or refractory chronic lymphocytic leukemia: a multicenter phase II trial of the German Chronic Lymphocytic Leukemia Study Group

PURPOSE

The objective of this trial was to evaluate safety and efficacy of bendamustine combined with rituximab (BR) in patients with relapsed and/or refractory chronic lymphocytic leukemia (CLL).

PATIENTS AND METHODS

Seventy-eight patients, including 22 patients with fludarabine-refractory disease (28.2%) and 14 patients (17.9%) with deletion of 17p, received BR chemoimmunotherapy. Bendamustine was administered at a dose of 70 mg/m(2) on days 1 and 2 combined with rituximab 375 mg/m(2) on day 0 of the first course and 500 mg/m(2) on day 1 during subsequent courses for up to six courses.

RESULTS

On the basis of intent-to-treat analysis, the overall response rate was 59.0% (95% CI, 47.3% to 70.0%). Complete response, partial response, and nodular partial response were achieved in 9.0%, 47.4%, and 2.6% of patients, respectively. Overall response rate was 45.5% in fludarabine-refractory patients and 60.5% in fludarabine-sensitive patients. Among genetic subgroups, 92.3% of patients with del(11q), 100% with trisomy 12, 7.1% with del(17p), and 58.7% with unmutated IGHV status responded to treatment. After a median follow-up time of 24 months, the median event-free survival was 14.7 months. Severe infections occurred in 12.8% of patients. Grade 3 or 4 neutropenia, thrombocytopenia, and anemia were documented in 23.1%, 28.2%, and 16.6% of patients, respectively.

CONCLUSION

Chemoimmunotherapy with BR is effective and safe in patients with relapsed CLL and has notable activity in fludarabine-refractory disease. Major but tolerable toxicities were myelosuppression and infections. These promising results encouraged us to initiate a further phase II trial evaluating the BR regimen in patients with previously untreated CLL.

Salvage therapy for relapsed chronic lymphocytic leukemia

Chronic lymphocytic leukemia is a common hematologic malignancy with a highly variable clinical course. While the median age at diagnosis is 72 years of age and fewer than 10% of patients are diagnosed before the age of 60 years, the majority of patients who require therapy will ultimately relapse. Advances in upfront therapy and supportive care have dramatically improved initial responses compared with traditional akylator-based chemotherapy. However, comparable results are not generally observed in the salvage setting. Careful planning that takes into account the duration of the initial response, patient age and/or comorbidities, and cytogenetic and molecular profiles are critical for the successful management of patients with relapsed chronic lymphocytic leukemia.

Personalizing treatment for chronic lymphocytic leukemia

Over the past few years, more effective therapies have emerged in the treatment of chronic lymphocytic leukemia (CLL); these are mainly combinations of immunotherapy with fludarabine-based regimens. Despite the higher response rates obtained with these more intensive treatments, they may not always be applicable. Patients with several comorbidities have an increased toxicity with these newer therapies. Effective tools to distinguish between fit and nonfit patients and new therapeutic approaches suitable for fragile patients with CLL are therefore necessary. Moreover, there is still a subset of patients who are refractory to standard fludarabine-based treatments who continue to have very poor survival. Efforts to understand the mechanisms of resistance to treatment in order to develop new therapeutic agents for those patients are mandatory. Finally, advances in the knowledge of the pathogenesis of CLL are promoting the emergence of drugs directed to new biological targets of this disease. Consequently, trials exploring the toxicity profile and efficacy of these new therapeutic agents, alone or in combination with standard treatments, are warranted.

Phase II study of dasatinib in relapsed or refractory chronic lymphocytic leukemia

PURPOSE

Chronic lymphocytic leukemia (CLL) cells treated with dasatinib in vitro undergo apoptosis via inhibition of Lyn kinase. Thus, in this study we tested the activity of dasatinib in patients with relapsed CLL.

EXPERIMENTAL DESIGN

Patients were eligible for this phase II trial if they had documented CLL/SLL and had failed at least 1 prior therapy with a fludarabine-containing regimen and if they required therapy according to NCI-WG criteria. The starting dose of dasatinib was 140 mg daily.

RESULTS

Fifteen patients were enrolled, with a median age of 59 and a median of 3 prior regimens. All patients had received fludarabine, and 5 were fludarabine-refractory. Eleven of the 15 (73%) had high risk del(11q) or del(17p) cytogenetics. The primary toxicity was myelosuppression, with grade 3 or 4 neutropenia and thrombocytopenia in 10 and 6 patients, respectively. Partial responses by NCI-WG criteria were achieved in 3 of the 15 patients (20%; 90% CI: 6-44). Among the remaining 12 patients, 5 had nodal responses by physical exam, and 1 patient had a nodal and lymphocyte response but with severe myelosuppression. Pharmacodynamic studies indicated apoptosis in peripheral blood CLL cells within 3 to 6 hours after dasatinib administration, associated with downregulation of Syk (spleen tyrosine kinase) mRNA.

CONCLUSIONS

Dasatinib as a single agent has activity in relapsed and refractory CLL.

Fludarabine, cyclophosphamide, and rituximab chemoimmunotherapy is highly effective treatment for relapsed patients with CLL

Optimal management of patients with relapsed/refractory chronic lymphocytic leukemia (CLL) is dictated by patient characteristics, prior therapy, and response to prior therapy. We report the final analysis of combined fludarabine, cyclophosphamide, and rituximab (FCR) for previously treated patients with CLL and identify patients who benefit most from this therapy. We explore efficacy of FCR in patients beyond first relapse, patients with prior exposure to fludarabine and alkylating agent combinations, and patients with prior exposure to rituximab. The FCR regimen was administered to 284 previously treated patients with CLL. Patients were assessed for response and progression by 1996 National Cancer Institute-Working Group (NCI-WG) criteria for CLL and followed for survival. The overall response rate was 74%, with 30% complete remission. The estimated median overall survival was 47 months and median progression-free survival for all patients was 21 months. Subgroup analyses indicated that the following patients were most suitable for FCR treatment: patients with up to 3 prior treatments, fludarabine-sensitive patients irrespective of prior rituximab exposure, and patients without chromosome 17 abnormalities. FCR is an active and well-tolerated therapy for patients with relapsed CLL. The addition of rituximab to FC improved quality and durability of response in this patient population.

Stem cell transplantation in chronic lymphocytic leukaemia - steering a safe course over shifting sands

There is no clear consensus regarding the optimal management of chronic lymphocytic leukaemia. Many patients are diagnosed at an advanced age and will die with chronic lymphocytic leukaemia, but of other unrelated causes. A significant minority are diagnosed at an earlier age, or with more aggressive disease, and despite chemotherapy, are likely to die of chronic lymphocytic leukaemia. The infusion of autologous or allogeneic haemopoietic stem cells, following a variety of conditioning regimes, offers the possibility of longer remissions or even cure. We explore the key questions facing clinicians in this field: Who is it best to transplant? When is it best to transplant? How is it best to transplant?

The treatment of relapsed refractory chronic lymphocytic leukemia

Despite the widespread use of highly effective chemoimmunotherapy (CIT), fludarabine-refractory chronic lymphocytic leukemia (CLL) remains a challenging clinical problem associated with poor overall survival (OS). The traditional definition, which includes those patients with no response or relapse within 6 months of fludarabine, is evolving with the recognition that even patients with longer remissions of up to several years after CIT have poor subsequent treatment response and survival. Approved therapeutic options for these patients remain limited, and the goal of therapy for physically fit patients is often to achieve adequate cytoreduction to proceed to allogeneic stem cell transplantation (alloSCT). Fortunately, several novel targeted therapeutics in clinical trials hold promise of significant benefit for this patient population. This review discusses the activity of available and novel therapeutics in fludarabine-refractory or fludarabine-resistant CLL as well as recently updated data on alloSCT in CLL.

NCI First International Workshop on the Biology, Prevention, and Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation: Report from the Committee on Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation

Relapse is a major cause of treatment failure after allogeneic hematopoietic stem cell transplantation (alloHSCT). Treatment options for relapse have been inadequate, and the majority of patients ultimately die of their disease. There is no standard approach to treating relapse after alloHSCT. Withdrawal of immune suppression and donor lymphocyte infusions are commonly used for all diseases; although these interventions are remarkably effective for relapsed chronic myelogenous leukemia, they have limited efficacy in other hematologic malignancies. Conventional and novel chemotherapy, monoclonal antibody therapy, targeted therapies, and second transplants have been utilized in a variety of relapsed diseases, but reports on these therapies are generally anecdotal and retrospective. As such, there is an immediate need for well-designed, disease-specific trials for treatment of relapse after alloHSCT. This report summarizes current treatment options under investigation for relapse after alloHSCT in a disease-specific manner. In addition, recommendations are provided for specific areas of research necessary in the treatment of relapse after alloHSCT.

Standards for the treatment of relapsed chronic lymphocytic leukemia: a case-based study

In recent years, considerable advances have been made in first-line treatment strategies for chronic lymphocytic leukemia (CLL). Combination of conventional chemotherapy with immunotherapeutic agents is currently considered the most active strategy, with improved progression-free survival and overall survival. However, patients are not cured and invariably experience relapsing disease requiring treatment. In contrast to the advances made in first-line treatment strategies, much less progress has been made for patients with relapsed and especially refractory CLL. The activity of most chemotherapeutic drugs used in CLL rely on intact p53 function, and repeated cycles of therapy might eventually result in drug resistance because of acquired cytogenetic alterations, mainly affecting genes involved in the p53 response. As a consequence, most commonly used treatment regimens are ineffective in patients with refractory disease. A number of promising alternative treatment approaches are currently under investigation. In this review, the approach to patients with relapsed and refractory CLL and current promising experimental treatment options for these distinct clinical patient categories are discussed.

Ofatumumab: a new CD20 monoclonal antibody therapy for B-cell chronic lymphocytic leukemia

Though most patients with chronic lymphocytic leukemia (CLL) respond to first-line therapy, all patients eventually relapse, after which therapeutic options are limited. Fludarabine-refractory patients have a particularly poor prognosis. The addition of the CD20 monoclonal antibody (MoAb) rituximab to chemotherapy in CLL has improved outcomes, particularly in early lines of therapy; however, the efficacy of rituximab monotherapy in CLL is limited, potentially in part because of reduced cell lysis via complement-dependent cytotoxicity (CDC) in this setting. Rituximab CDC is dependent on CD20 expression; CLL cells underexpress CD20. Ofatumumab is a human MoAb that targets an epitope encompassing the membrane-proximal small-loop on the CD20 molecule, which differs from the binding location of rituximab. In vitro studies with ofatumumab have demonstrated that it is significantly more effective than rituximab at corresponding dose levels at lysing CLL cells and B-cell lines, especially those with low CD20 copy numbers. In patients with CLL refractory to both fludarabine and alemtuzumab or refractory to fludarabine with bulky lymphadenopathy and, therefore, less suitable for treatment with the CD52 MoAb alemtuzumab, results from the planned interim analysis showed an encouraging response rate with ofatumumab (Independent Endpoint Review Committee evaluated) and survival parameters, which seemed to be higher than those reported from a historical assessment of other salvage therapies in a corresponding group of patients. Ofatumumab was also well tolerated; the most common adverse events were transient grade 1 or 2 infusion reactions and infections. Ongoing trials will help confirm the role of ofatumumab in CLL, in addition to the effect of this agent in combination with chemotherapies and other MoAbs.

Allogeneic transplantation for chronic lymphocytic leukemia

Even if Chronic lymphocytic leukemia (CLL) often has an indolent behavior with good responsiveness to cytoreductive treatment, about 20% of the patients, so called “poor-risk” patients, show an aggressive course and die within a few years despite early intensive therapies. Criteria for poor-risk disease according to the European Bone Marrow Transplantation (EBMT) CLL Transplant Consensus are: purine analogue refractoriness, early relapse after purine analogue combination therapy, CLL with p53 lesion requiring treatment.

Allogeneic transplant has potential curative role in CLL, however burden with very high transplant related mortality (TRM) rates of 38–50%. A major advance in reducing the short-term morbidity and mortality of allogeneic stem cell transplantation (SCT) has been the introduction of non-myeloablative or reduced intensity conditioning (RIC) regimens to allow engraftment of allogeneic stem cells. There is no doubt that the crucial therapeutic principle of allo-SCT in CLL is graft versus leukemia (GVL) activity.

The major complications of allogeneic SCT in CLL are: chronic graft-versus-host-disease (GVHD) affecting quality of life, high graft rejection and infection rates correlated with preexisting immunosuppression. Disease relapse remains the major cause of failure after RIC allo-HCT in CLL patients.

Sensitive minimal residual disease (MRD) quantification has strong prognostic impact after transplant.

Chemoimmunotherapy of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) has long been regarded as an incurable disease of the elderly, worthy only of symptom palliation. Past generations of chemotherapy resulted in improved response rates, but did not change the natural history of the disease. Prolonged remissions and improvements in survival are, however, now possible owing to therapeutic advances including the use of purine analogs as frontline treatment and the emergence of monoclonal antibody-containing chemoimmunotherapy combinations. Moreover, consolidation strategies using non-cross resistant agents have improved the success rates of patients with residual disease at the end of induction treatment. Together, these new developments promise to deliver the tools necessary to render a state of minimal residual disease negativity in the majority of patients commencing treatment for CLL. This Review will outline the history and results of chemoimmunotherapy regimens that contain purine analogs and rituximab-the most successful combinations developed to date. We will also discuss how new developments in induction and consolidation strategies are leading the path towards cure.

Phase 2 and pharmacodynamic study of oral forodesine in patients with advanced, fludarabine-treated chronic lymphocytic leukemia

Forodesine is a new and potent purine nucleoside phosphorylase (PNP) inhibitor. Patients with chronic lymphocytic leukemia (CLL) with primary resistance to fludarabine-based therapy or with progressive disease were eligible for oral forodesine (200 mg/d) for up to 24 weeks. Eight patients with median lymphocyte count of 35.9 x 10(9)/L and median serum beta2 microglobulin level of 6.45 mg/L were treated. Six had Rai stage III to IV and were previously heavily treated (median prior therapy = 5). Two had transient decrease in lymphocyte count to normal, whereas in 5, disease progressed. Adverse events were mild. Steady-state level of forodesine ranged from 200 to 1300 nM and did not reach desired 2 microM level. PNP inhibition ranged from 57% to 89% and steady-state 2'-deoxyguanosine (dGuo) concentration median was 1.8 microM. Intracellular deoxyguanosine triphosphate (dGTP) increase was very modest, from median of 6 microM to 10 microM. Compared with in vivo, in vitro incubations of CLL lymphocytes with 10 or 20 microM dGuo and forodesine (2 microM) resulted in accumulation of higher levels of dGTP (40-250 microM) which resulted in increase in apoptosis. Forodesine has biologic activity in CLL; pharmacodynamic parameters suggest that an alternate dosing schedule and/or higher doses to achieve greater intracellular dGTP may be beneficial in this patient population.

Interstrand crosslink inducing agents in pretransplant conditioning therapy for hematologic malignancies

Despite successful molecularly targeted, highly specific, therapies for hematologic malignancies, the DNA interstrand crosslinking agents, which are among the oldest and least specific cytotoxic drugs, still have an important role. This is particularly true in stem cell transplantation, where virtually every patient receives conditioning therapy with a DNA-alkylating agent-based program. However, due to concern about serious additive toxicities with combinations of different alkylating drugs, the last several years have seen nucleoside analogs, whose cytotoxic action follows vastly different molecular pathways, introduced in combination with alkylating agents. The mechanistic differences paired with different metabolic pathways for the respective drugs have clinically translated into increased safety without appreciable loss of antileukemic activity. In this report, we review pre-clinical evidence for synergistic antileukemic activity when nucleoside analog(s) and DNA-alkylating agent(s) are combined in the most appropriate manner(s), without a measurable decrease in clinical efficacy compared with the more established alkylating agent combinations. Data from our own laboratory using combinations of fludarabine, clofarabine, and busulfan as prototype representatives for these respective classes of cytotoxic agents are combined with information from other investigators to explain how the observed molecular events will result in greatly enhanced synergistic cytotoxicity. We further present possible mechanistic pathways for such desirable cytotoxic synergism. Finally, we propose how this information-backed hypothesis can be incorporated in the design of the next generation conditioning therapy programs in stem cell transplantation to optimize antileukemic efficacy while still safeguarding patient safety.

Treatment of patients with fludarabine-refractory chronic lymphocytic leukemia: need for new treatment options

Fludarabine-refractory chronic lymphocytic leukemia is associated with poor survival rates. Chemoimmunotherapy combinations that include purine analogs, alkylating agents, and monoclonal antibodies have shown the highest response rates to date. Intensive treatment approaches can be associated with poor tolerability that is often characterized by deteriorating immune functions and high infection rates. Treatment with some monoclonal antibodies is often complicated by infusion-related adverse events and increased risk of infections. Several novel agents are currently being investigated for this difficult-to-treat patient population. Ofatumumab is an anti-CD20 monoclonal antibody that targets a different epitope from the one targeted by rituximab and, it has shown promising antileukemia activity. Lenalidomide is an immunomodulatory agent that has shown promising activity in patients with fludarabine-refractory chronic lymphocytic leukemia, many of whom had poor prognostic features and bulky disease. Encouraging results have been observed with each of these agents individually. However, given the diverse mechanisms governing CLL pathogenesis and disease progression, ongoing clinical trials combinations of these agents may improve clinical outcomes for this patient population.

First-line treatment of chronic lymphocytic leukemia: role of alemtuzumab

The CD52-targeting antibody alemtuzumab is established in clinical practice with convincing activity in relapsed and refractory chronic lymphocytic leukemia (CLL), particularly in patients with high-risk features and adverse prognosis. In the CAM307 study alemtuzumab was tested and finally approved as a first-line single agent, even though the hurdle with chlorambucil as the contender was not set very high. Within clinical trials, the drug demonstrated an excellent ability to eliminate minimal residual disease in blood and bone marrow, which has been correlated with a corresponding survival advantage in patients. However, in the maintenance setting, infectious complications due to severe T cell suppression have been highlighted and do not allow clinicans to use alemtuzumab outside of clinical trials. This review discusses potential therapeutic niches and future applications of alemtuzumab with a focus on CLL front-line treatment.

Alemtuzumab maintenance may safely prolong chemotherapy-free intervals in chronic lymphocytic leukemia

This prospective, single-arm study utilized alemtuzumab as a single agent in a novel maintenance schedule in previously treated chronic lymphocytic leukemia patients with the goal of delaying progression of disease and requirement for chemotherapy. In previously treated CLL patients who had achieved stable disease or better, the following schedule of subcutaneous alemtuzumab was administered: a dose escalation in the first week (3, 10 and 30 mg), followed by 7 weeks of 30 mg alemtuzumab once weekly, 16 weeks of 30 mg once every 2 weeks, followed by once every 3 weeks for 24 weeks. Thus, the entire duration of the planned treatment was 48 weeks. A total of 12 patients were enrolled 11 of which had at least one marker of poor prognosis (unmutated, Zap 70+, CD38+, del11q and del17p). The median chemotherapy-free interval was 13 months, and the median time to disease progression was 10 months. Three patients achieved a CR, one achieved nPR, one had a PR, five failed and two had shown a beneficial response but because of recurrent ITP had to stop alemtuzumab. In six of the 10 patients with previously relapsed disease, the chemotherapy-free interval was longer than their prior chemotherapy-free period. One patient had a reactivation of CMV antigenemia, and another had a bacterial pneumonia. There were no grade 3 or 4 toxicities. Alemtuzumab used in a maintenance schedule is a potentially safe and useful tool in delaying disease progression and chemotherapy-free intervals in previously treated CLL patients.

Ofatumumab as single-agent CD20 immunotherapy in fludarabine-refractory chronic lymphocytic leukemia

PURPOSE

New treatments are needed for patients with fludarabine- and alemtuzumab-refractory (FA-ref) chronic lymphocytic leukemia (CLL) or patients with fludarabine-refractory CLL with bulky (> 5 cm) lymphadenopathy (BF-ref) who are less suitable for alemtuzumab treatment; these groups have poor outcomes with available salvage regimens. Ofatumumab (HuMax-CD20) is a human monoclonal antibody targeting a distinct small-loop epitope on the CD20 molecule. We conducted an international clinical study to evaluate the efficacy and safety of ofatumumab in patients with FA-ref and BF-ref CLL.

PATIENTS AND METHODS

Patients received eight weekly infusions of ofatumumab followed by four monthly infusions during a 24-week period (dose 1 = 300 mg; doses 2 to 12 = 2,000 mg); response by an independent review committee (1996 National Cancer Institute Working Group criteria) was assessed every 4 weeks until week 24 and then every 3 months until month 24.

RESULTS

This planned interim analysis included 138 treated patients with FA-ref (n = 59) and BF-ref (n = 79) CLL. The overall response rates (primary end point) were 58% [corrected] and 47% in the FA-ref and BF-ref groups, respectively. Complete resolution of constitutional symptoms and improved performance status occurred in 57% and 48% of patients, respectively. Median progression-free survival and overall survival times were 5.7 and 13.7 months in the FA-ref group, respectively, and 5.9 and 15.4 months in the BF-ref group, respectively. The most common adverse events during treatment were infusion reactions and infections, which were primarily grade 1 or 2 events. Hematologic events during treatment included anemia and neutropenia.

CONCLUSION

Ofatumumab is an active, well-tolerated treatment providing clear clinical improvements for fludarabine-refractory patients with very poor-prognosis CLL.

Transplantation in chronic lymphocytic leukemia: timing and expectations

Stem cell transplantation in chronic lymphocytic leukemia (CLL) is an evolving field. Younger patients with high-risk disease might derive the greatest benefit from this approach and the availability of reduced-intensity conditioning regimens has made allogeneic stem cell transplantation more relevant to patients with CLL. Patient selection, timing of transplantation, and method of conditioning, stem cell delivery and immunosuppression appear to influence outcomes. We collect and review the available data to assist clinical decision-making in this field.

High-risk fludarabine-pretreated B-cell chronic lymphocytic leukemia's high response rate following sequential DHAP and alemtuzumab administration though in absence of molecular remission

B-CLL patients with resistant/relapsed disease or adverse prognostic factors at presentation are suitable for alternative treatments. In the present pilot study we investigated a novel intensive chemo-immunotherapy approach for high-risk, fludarabine pretreated patients. Ten patients with resistant/relapsed, advanced stage BCLL were included. Age was 37-60 yr (median 53). All but one had an unmutated IgVH status. The treatment schedule included debulking with two DHAP courses followed by alemtuzumab (30 mg, eight doses), followed by peripheral blood progenitor cell (PBPC) mobilization with intermediate/high-dose cyclophosphamide and by autografting after high-dose mitoxantrone+L-Pam. The DHAP-alemtuzumab combination was highly effective. Eight patients out of 10 responded to DHAP, with a single complete remission. Following alemtuzumab, the number of overall responses increased to nine, and the complete remissions to five. After alemtuzumab PB double-positive clonal CD5+/CD19+ lymphocytes dropped, with median purification rate 99.95%. Owing to poor PBPC mobilization, only five patients underwent autografting, and three of these experienced post-graft recurrence. The six patients entering complete remission were free of disease 3-23 mo after study entry, and three of them were still in remission at 3, 7, and 22 mo. However, molecular evaluation regularly revealed persistence of minimal residual disease, both in all PBPC collections tested and in post-treatment follow-up samples. The use of DHAP/alemtuzumab appears useful to re-induce disease remission in relapsed/refractory, high-risk B-CLL patients. However, the addition of autograft was not usually feasible and of questionable clinical use. Other strategies should thus be considered for remission maintenance.

A phase II study of Campath-1H in children with relapsed or refractory acute lymphoblastic leukemia: a Children's Oncology Group report

BACKGROUND

Despite the increasing cure rates for children with acute lymphoblastic leukemia (ALL), patients who relapse continue to have poor prognosis. The Children's Oncology Group (COG) conducted a limited institution Phase II trial of Campath-1H, a monoclonal antibody that targets CD52 on leukemic cells, in children with relapsed or refractory ALL.

METHODS

From October 2005 to December 2006, 13 eligible patients were enrolled on the COG phase II study of Campath-1H (ADVL0222). Campath-1H was initially administered as an intravenous infusion over 2 hr, five times per week for 1 week, then three times per week for three additional weeks. Patients with stable disease or better on day 29 could continue on to combination therapy with Campath-1H, methotrexate, and 6-mercaptopurine for two additional cycles.

RESULTS

One of 13 patients enrolled had a complete response to Campath-1H and 4 had stable disease. Dose limiting toxicity occurred in two out of nine fully evaluable patients (Grade IV pain and Grade III allergic reaction/hypersensitivity). No patients received combination therapy. Serum Campath-1H concentrations appeared to be somewhat lower in children with ALL compared with adult patients with chronic lymphocytic leukemia.

CONCLUSION

Although a single complete response was observed, activity of single agent Campath-1H appears limited. Our study does not support future single agent evaluation of Campath-1H in children with relapsed ALL.

Chronic lymphocytic leukemia: treatment options for patients with refractory disease

Patients with purine analogue-refractory chronic lymphocytic leukemia (CLL) have short survival and limited treatment options. Defining the best salvage strategies for this population is challenging, because limited data are available from clinical trials, and because studies have enrolled mixed populations (patients with recurrent and refractory disease or patients with refractory disease and Richter transformation). Moreover, patients with refractory CLL have a high incidence of unfavorable molecular and clinical features, such as high-risk genomic profiles, unmutated immunoglobulin heavy-chain genes, expression of zeta-chain-associated protein kinase 70, and bulky lymphadenopathies. These patients are also severely immunosuppressed because of the underlying disease and the treatments received, and experience a high rate of infectious complications that pose an additional difficulty in selecting treatment. Despite these challenges, in parallel with better characterizations of the biologic features of refractory CLL, the number of available treatment modalities for this population has increased. Several chemoimmunotherapy combinations have been developed, and novel agents with a different mechanism of action are being investigated in clinical trials. Furthermore, allogeneic stem cell transplantation with nonmyeloablative conditioning regimens is a therapeutic strategy that is increasingly offered to patients with refractory CLL.

Antileukemic activity of valproic acid in chronic lymphocytic leukemia B cells defined by microarray analysis

Epigenetic code modifications by histone deacetylase inhibitors have recently been proposed as potential new therapies for hematological malignancies. Chronic lymphocytic leukemia (CLL) remains incurable despite the introduction of new treatments. CLL B cells are characterized by an apoptosis defect rather than excessive proliferation, but proliferation centers have been found in organs such as the bone marrow and lymph nodes. In this study, we analyzed gene expression modifications in CLL B cells after treatment with valproic acid (VPA), a well-tolerated anti-epileptic drug with HDAC inhibitory activity. CLL B cells obtained from 14 patients were treated in vitro with a concentration of 1 mM VPA for 4 h. VPA effects on gene expression were thereafter studied using Affymetrix technology, and some identified genes were validated by real-time PCR and western blot. We observed that VPA induced apoptosis by downregulating several anti-apoptotic genes and by upregulating pro-apoptotic genes. Furthermore, VPA significantly increased chemosensitivity to fludarabine, flavopiridol, bortezomib, thalidomide and lenalidomide. VPA inhibited the proliferation of CpG/IL2-stimulated CLL B cells and modulated many cell cycle messenger RNAs. In conclusion, exposure of CLL B cells to VPA induced apoptosis, potentiated chemotherapeutic agent effects and inhibited proliferation. These data strongly suggest the use of VPA in CLL treatment, particularly in combination with antileukemia agents.

Detailed analysis of p53 pathway defects in fludarabine-refractory chronic lymphocytic leukemia (CLL): dissecting the contribution of 17p deletion, TP53 mutation, p53-p21 dysfunction, and miR34a in a prospective clinical trial

The prognosis of fludarabine (F)-refractory chronic lymphocytic leukemia (CLL) is very poor, and underlying mechanisms are only partly understood. To assess the contribution of p53 abnormalities to F-refractory CLL, we studied TP53 mutations in the CLL2H trial (subcutaneous alemtuzumab; n = 99). We found TP53 mutations in 37% of patients. Twelve of 67 (18%) patients without the 17p deletion showed a TP53 mutation and 50% showed evidence of uniparental disomy. A total of 75% of cases with TP53 mutation (without 17p-) showed clonal evolution/expansion. TP53 mutations had no impact on overall survival (P = .48). CLL with the 17p deletion or TP53 mutation showed very low miR-34a expression. To investigate the mechanisms underlying refractory CLL beyond p53, we studied cases without 17p-/TP53 mutation in detail. In several paired samples before and after F-refractory disease, no change in p21/p53 induction was observed after DNA damage. Although TP53 mutations and 17p deletions are found in a high proportion of F-refractory CLL, more than half of the cases cannot be explained by p53 defects (deletion or mutation), and alternative mechanisms need to be investigated. Alemtuzumab is effective irrespective of genetic high-risk subgroups with TP53 mutations. These clinical trials are registered at www.clinicaltrials.gov as #NCT00274976.

Allogeneic hematopoietic cell transplantation for chronic lymphocytic leukemia: ready for prime time?

The development of reduced intensity conditioning regimens has increased the number of patients diagnosed with chronic lymphocytic leukemia that are referred for allogeneic hematopoietic cell transplantation (allo-HCT). However, given the toxicity of allo-HCT, it should only be offered to eligible patients whose life expectancy is significantly reduced by the disease. Accordingly, the European Group of Blood and Marrow Transplantation has recently identified those patients in whom allo-HCT could be a reasonable therapeutic approach. In this review, we have evaluated the outcome of chronic lymphocytic leukemia patients undergoing allo-HCT, either after conventional or reduced intensity conditioning regimens, in the context of current nontransplantation strategies. We have also analyzed the most important predisposing factors that might interfere with the procedure as well as posttransplantation complications that are particularly common in these patients. Finally, we have addressed the most relevant factors when deciding what patients should be considered for allo-HCT and the timing of the procedure.

Subcutaneous alemtuzumab in fludarabine-refractory chronic lymphocytic leukemia: clinical results and prognostic marker analyses from the CLL2H study of the German Chronic Lymphocytic Leukemia Study Group

PURPOSE

The phase II CLL2H trial evaluated safety and efficacy of subcutaneous alemtuzumab in patients with fludarabine-refractory chronic lymphocytic leukemia (CLL). Clinical and biologic markers were evaluated for their impacts on outcome.

PATIENTS AND METHODS

One hundred nine patients were enrolled, and 103 received at least one dose of alemtuzumab. After dose escalation, alemtuzumab was administered subcutaneously at 30 mg three times weekly for up to 12 weeks. Response was assessed every 4 weeks during treatment and quarterly thereafter.

RESULTS

The overall response rate was 34% (complete response, 4%; partial response, 30%). The median progression-free survival was 7.7 months, and the median overall survival (OS) was 19.1 months. Grades 3 to 4 neutropenia, thrombocytopenia, and anemia occurred in 56%, 57%, and 49% of patients, respectively. Grades 3 to 4 noncytomegalovirus and cytomegalovirus infections occurred in 29% and 8% of patients, respectively. Injection-site skin reactions were generally mild. Efficacy did not vary significantly in subgroups defined by genetic parameters (in particular, in 17p deletion, 11q deletion, mutated TP53, and unmutated VH), but efficacy was inferior in patients with increased beta2-microglobulin (beta2-MG) and thymidine kinase (TK). In multivariate analysis of clinical and biologic variables, age, performance status, beta2-MG, and TK were independent prognostic factors for OS.

CONCLUSION

Subcutaneous alemtuzumab appears as effective and safe as intravenous alemtuzumab in fludarabine-refractory CLL. Subcutaneous administration should be the preferred delivery route because of its efficacy, convenience, improved adverse effect profile, and cost savings. In contrast to chemotherapy-based therapy, alemtuzumab treatment overcomes the adverse prognostic impact of VH mutation status, TP53 mutation, and genomic aberrations.

An observational study of once weekly intravenous ganciclovir as CMV prophylaxis in heavily pre-treated chronic lymphocytic leukemia patients receiving subcutaneous alemtuzumab

Fifteen consecutive resistant/relapsed chronic lymphocytic leukemia (CLL) patients (median age: 65 years) received alemtuzumab for 16 consecutive weeks. All patients had negative CMV anti genemia at baseline. Five patients received oral acyclovir 800 mg twice a day for CMV prophylaxis and 10 patients got intravenous (iv) ganciclovir 7.5 mg/kg once a week. A total of five CMV reactivations occurred, four in the acyclovir and one in the ganciclovir prophylaxis group. Alemtuzumab was then discontinued and all patients were treated with iv ganciclovir 7.5 mg/kg per day. All patients achieved negative CMV anti genemia after a median of 15 days of therapy. Weekly iv ganciclovir prophylaxis and alemtuzumab treatment were then restarted without any further CMV reactivations. In conclusion, weekly iv ganciclovir appears feasible and effective in preventing CMV reactivation and disease in this setting of high-risk immunocompromised patients, allowing an easier management of a therapy otherwise difficult to be routinely used.

Treatment of fludarabine-refractory chronic lymphocytic leukemia

The development of resistance to purine analogs defines a poor-risk subset of patients with chronic lymphocytic leukemia (CLL). Although in recent years chemoimmunotherapeutic combinations such as fludarabine, cyclophosphamide, and rituximab have induced response rates of 95% in previously untreated patients and increased the rates of failure-free survival, CLL remains incurable for many patients because of a lack of disease response or the development of refractoriness to fludarabine. Fludarabine-refractory disease is defined as CLL that does not respond to fludarabine or that recurs within 6 months of treatment with a fludarabine-containing regimen. The natural course of the disease is associated with poor survival. Salvage therapeutic strategies include alemtuzumab-containing regimens, targeted agents, and allogeneic stem cell transplantation. Single-agent alemtuzumab induces response in up to 40% of patients with fludarabine-refractory CLL, but responses are not durable, and the median survival is approximately 1 to 2 years. Alemtuzumab is also combined with fludarabine, cyclophosphamide, and/or rituximab, and other agents such as lenalidomide and flavopiridol, as well as targeted agents, and used in fludarabine-refractory CLL. Cumulative evidence suggests that allogeneic stem cell transplantation is an efficacious therapeutic strategy for patients who do not respond to fludarabine or who develop disease recurrence within 12 months after purine analog treatment. In conclusion, chemoimmunotherapy regimens that include alemtuzumab and/or rituximab and allogeneic stem cell transplantation improve the prognosis of this disease, but there is a continued need for novel, more effective therapies.

The role of stem cell transplantation in the management of chronic lymphocytic leukaemia

The majority of patients diagnosed with chronic lymphocytic leukaemia (CLL) will ultimately die of their disease. Stem cell transplantation (SCT) remains the only treatment modality capable of cure, but has traditionally been associated with very high morbidity and mortality. We review the results of myeloablative autologous and allogeneic SCT in CLL, discuss the evolution of the new non-myeloablative approaches, and make recommendations for when SCT should be considered in patients with CLL.

Chronic lymphocytic leukemia: new concepts and emerging therapies

OPINION STATEMENT

Remarkable progress in elucidating the biology of chronic lymphocytic leukemia (CLL) has been made over the last two decades. Improved understanding of CLL has lead to new prognostic tools and therapeutic options, and holds promise for eventually finding a cure for this disease. Challenges lie in incorporating the various treatment modalities, including chemotherapy, monoclonal antibodies, immunotherapeutic strategies and novel small molecules, into a comprehensive treatment strategy guided by the biological complexity of CLL.

The effect of in vivo T cell depletion with alemtuzumab on reduced-intensity allogeneic hematopoietic cell transplantation for chronic lymphocytic leukemia

Reduced-intensity conditioning (RIC) allogeneic hematopoietic cell transplantation is increasingly considered for patients with chronic lymphocytic leukemia (CLL). To investigate the impact of in vivo T cell depletion with alemtuzumab on the incidence of graft-versus-host disease (GVHD), nonrelapse mortality (NRM), progression-free survival (PFS), and overall survival (OS), we retrospectively analyzed the outcomes of 62 consecutive CLL patients conditioned with fludarabine and melphalan at 4 institutions. For GVHD prophylaxis, 41 patients (cohort 1) received alemtuzumab and cyclosporin; and 21 patients (cohort 2) received cyclosporin plus methotrexate or mycophenolate. Donors were 50 siblings and 12 unrelated volunteers. Twenty-two (36%) patients received donor lymphocyte infusions (DLI), 20 (49%) from cohort 1 and 2 (10%) from cohort 2 (P=.002). Grade III-IV acute GVHD (aGVHD) was observed in 20% and 38% of patients from cohorts 1 and 2, respectively (P=.14). Extensive chronic GVHD (cGVHD) was observed in 10% and 48% of patients from cohorts 1 and 2, respectively (P=.03). There was a trend toward a higher viral infection rate in cohort 1 compared to cohort 2 (68% versus 43%, P=.062), but the incidence of cytomegalovirus (CMV) reactivation was not significantly different. The 3-year OS, PFS, NRM, and relapse rates were 65%, 39%, 28%, and 32%, respectively, for cohort 1; and 57%, 47%, 34%, and 20%, respectively, for cohort 2 (P=.629, P=.361, P=.735, and P=0.112, respectively). In conclusion, both methods of GVHD prophylaxis were equivalent in terms of survival. The administration of alemtuzumab led to reduced cGVHD, possibly improving quality of life.

Five-year follow-up of patients with advanced chronic lymphocytic leukemia treated with allogeneic hematopoietic cell transplantation after nonmyeloablative conditioning

PURPOSE

We reported encouraging early results of allogeneic hematopoietic cell transplantation (HCT) after nonmyeloablative conditioning in 64 patients who had advanced chronic lymphocytic leukemia (CLL). Here, we have extended the follow-up to a median of 5 years and have included data on an additional 18 patients.

PATIENTS AND METHODS

Eighty-two patients, age 42 to 72 years, who had fludarabine-refractory CLL were conditioned with 2 Gy total-body irradiation alone or combined with fludarabine followed by HCT from related (n = 52) or unrelated (n = 30) donors.

RESULTS

Complete remission (CR) and partial remission were achieved in 55% and 15% of patients, respectively. Higher CR rates were noted after unrelated HCT (67% v 48%). The 5-year incidences of nonrelapse mortality (NRM), progression/relapse, overall survival, and progression-free survival were 23%, 38%, 50%, and 39%, respectively. Among 25 patients initially reported in CR, 8% relapsed and 8% died as a result of NRM, whereas 84% have remained alive and in CR. Among 14 responding patients who were tested and who had molecular eradication of their disease, two died as a result of NRM, two relapsed, and 10 have remained negative. At 5 years, 76% of living patients were entirely well, whereas 24% continued to receive immunosuppression for chronic graft-versus-host disease; the median performance status in each group was 100% and 90%, respectively. Lymphadenopathy > or = 5 cm, but not cytogenetic abnormalities at HCT, predicted relapse. In a risk-stratification model, patients who had lymphadenopathy less than 5 cm and no comorbidities had a 5-year OS of 71%.

CONCLUSION

Nonmyeloablative HCT resulted in a median survival of 5 years for patients who had fludarabine-refractory CLL with sustained remissions and in the continued resolution of chronic graft-versus-host disease in surviving patients.

Lenalidomide induces complete and partial remissions in patients with relapsed and refractory chronic lymphocytic leukemia

This study investigated the activity of lenalidomide in patients with relapsed/refractory chronic lymphocytic leukemia (CLL). Lenalidomide was given at 10 mg daily with dose escalation up to 25 mg daily. Three patients (7%) achieved a complete response (CR), one a nodular partial remission, and 10 patients a partial remission (PR), for an overall response (OR) rate of 32%. Treatment with lenalidomide was associated with an OR rate of 31% in patients with 11q or 17p deletion, of 24% in patients with unmutated V(H), and of 25% in patients with fludarabine-refractory disease. The most common toxicity was myelosuppression, and the median daily dose of lenalidomide tolerated was 10 mg. Plasma levels of angiogenic factors, inflammatory cytokines, and cytokine receptors were measured at baseline, day 7, and day 28. There was a dramatic increase in median interleukin (IL)-6, IL-10, IL-2, and tumor necrosis factor receptor-1 levels on day 7, whereas no changes were observed in median vascular endothelial growth factor levels (20 patients studied). According to our experience, lenalidomide given as a continuous treatment has antitumor activity in heavily pretreated patients with CLL.

Phase I trial of nelarabine in indolent leukemias

PURPOSE

To test whether nelarabine is an effective agent for indolent leukemias and to evaluate whether there is a relationship between cellular pharmacokinetics of the analog triphosphate and clinical responses.

PATIENTS AND METHODS

Thirty-five patients with relapsed/refractory leukemias (n = 24, B-cell chronic lymphocytic leukemia and n = 11, T-cell prolymphocytic leukemia) were entered onto three different protocols. For schedule A, patient received nelarabine daily for 5 days, whereas for schedule B, nelarabine was administered on days 1, 3, and 5. Schedule C was similar to schedule B except that fludarabine was also infused. Plasma and cellular pharmacokinetics were studied during the first cycle.

RESULTS

Responses were achieved in 20%, 15%, and 63% of patients receiving schedule A, B, and C, respectively. Histologic category, number of prior therapies, and fludarabine refractoriness did not influence the response rate. The most common nonhematologic toxicity was peripheral neuropathy. Grade 4 neutropenia and thrombocytopenia complicated 23% and 26% of courses respectively, and were significantly more frequent among patients with pre-existing marrow failure. Pharmacokinetics of plasma nelarabine and arabinosylguanine (ara-G) and of cellular ara-G triphosphate (ara-GTP) were similar in the two groups of diagnoses, and the elimination of ara-GTP from leukemia cells was slow (median, > 24 hours). The median peak intracellular concentrations of ara-GTP were significantly different (P = .0003) between responders (440 micromol/L; range, 35 to 1,438 micromol/L; n = 10) and nonresponders (50 micromol/L; range, 22 to 178 micromol/L; n = 15).

CONCLUSION

Nelarabine is an effective regimen against indolent leukemias, and combining it with fludarabine was most promising. Determination of tumor cell ara-GTP levels may provide a predictive test for response to nelarabine.

Stem cell transplantation in poor-risk chronic lymphocytic leukemia: assessment of post-transplant minimal residual disease using four- and six-color flow cytometry and allele-specific RQ-PCR

A total of 178 bone marrow samples were taken for minimal residual disease (MRD) analysis after 34 stem cell transplantations for poor-risk chronic lymphocytic leukemia, and 86 of them were analyzed in parallel by flow cytometry and allele-specific oligonucleotide-PCR (ASO-PCR). ASO primer was successfully designed for all patients whose frozen diagnosis samples were available. Flow cytometry and ASO-PCR were concordant, i.e. both either positive or both negative, in 78% of the analyses. Flow cytometry did not detect MRD in any of the samples that were PCR-negative cases. In contrast, ASO-PCR detected MRD in samples that were negative for MRD by flow cytometry in 22% of the analyses. In one patient, the immunophenotype but not the IgV(H) gene sequence had changed during a course of the disease, and MRD could not be followed by flow cytometry. In the remaining cases, the discrepancy was due to a higher sensitivity of ASO-PCR. Autologous stem cell transplantation resulted in clinical complete response in 87% (20/23) of the patients. By flow cytometry, 35% (8/23) of autotransplanted patients became MRD-negative, but only 12.5% (2/16) PCR-negative (sensitivity of ASO-PCR <0.001 and <0.01, respectively). All allotransplanted patients achieved or maintained hematological CR, and five out of nine patients (56%) became PCR-negative (sensitivity of PCR between <0.001 and <0.003), two of them having non-myeloablative conditioning. None of the patients who became PCR-negative after allogeneic transplantation have relapsed.