Low-dose alemtuzumab (Campath®) in myeloablative allogeneic stem cell transplantation for CD52-positive malignancies: decreased incidence of acute graft-versus-host-disease with unique pharmacokinetics

Hematopoietic Cell Transplantation, Version 2.2020, NCCN Clinical Practice Guidelines in Oncology

Hematopoietic cell transplantation (HCT) involves the infusion of hematopoietic progenitor cells into patients with hematologic disorders with the goal of re-establishing normal hematopoietic and immune function. HCT is classified as autologous or allogeneic based on the origin of hematopoietic cells. Autologous HCT uses the patient's own cells while allogeneic HCT uses hematopoietic cells from a human leukocyte antigen-compatible donor. Allogeneic HCT is a potentially curative treatment option for patients with certain types of hematologic malignancies, and autologous HCT is primarily used to support patients undergoing high-dose chemotherapy. Advances in HCT methods and supportive care in recent decades have led to improved survival after HCT; however, disease relapse and posttransplant complications still commonly occur in both autologous and allogeneic HCT recipients. Allogeneic HCT recipients may also develop acute and/or chronic graft-versus-host disease (GVHD), which results in immune-mediated cellular injury of several organs. The NCCN Guidelines for Hematopoietic Cell Transplantation focus on recommendations for pretransplant recipient evaluation and the management of GVHD in adult patients with malignant disease.

Emerging strategies for enhancing the homing of hematopoietic stem cells to the bone marrow after transplantation

Bone marrow failure is the primary cause of death after nuclear accidents or intentional exposure to high or low doses of ionizing radiation. Hematopoietic stem cell transplantation is the most potent treatment procedure for patients suffering from several hematopoietic malignancies arising after radiation injuries. Successful hematopoietic recovery after transplantation depends on efficient homing and subsequent engraftment of hematopoietic stem cells in specific niches within the bone marrow. It is a rapid and coordinated process in which circulating cells actively enter the bone marrow through the process known as transvascular migration, which involves the tightly regulated relay of events that finally leads to homing of cells in the bone marrow. Various adhesion molecules, chemokines, glycoproteins, integrins, present both on the surface of stem cells and sinusoidal endothelium plays a critical role in transvascular migration. But despite having an in-depth knowledge of homing and engraftment and the key events that regulate it, we are still not completely able to avoid graft failures and post-transplant mortalities. This deems it necessary to design a flawless plan for successful transplantation. Here, in this review, we will discuss the current clinical methods used to overcome graft failures and their flaws. We will also discuss, what are the new approaches developed in the past 10-12 years to selectively deliver the hematopoietic stem cells in the bone marrow by adopting proper targeting strategies that can help revolutionize the field of regenerative and translational medicine.

A comparative study of reduced dose alemtuzumab in matched unrelated donor and related donor reduced intensity transplants

In vivo T cell depletion with 100 mg alemtuzumab prevents graft-versus-host disease (GVHD) in reduced intensity conditioned transplants but is associated with delayed immune reconstitution, a higher risk of infection and relapse. De-escalation studies have shown that a reduced dose of 30 mg is as effective as 100 mg in preventing GVHD in matched related donor (MRD) transplants. Dose reduction in matched unrelated donor (MUD) transplants is feasible but the comparative efficacy of alemtuzumab in this setting is not known and opinions vary widely concerning the optimal level of GVHD prophylaxis that should be achieved. Through retrospective analysis we made an objective comparison of MUD transplants receiving an empirically reduced dose of 60 mg, with MRD transplants receiving a 30 mg dose. We observed proportionate levels of alemtuzumab according to dose but an inverse relationship with body surface area particularly in MRD transplants. MUD transplants experienced more acute and chronic GVHD, higher T cell chimerism, more sustained use of ciclosporin and less need for donor lymphocyte infusion than MRD transplants. Thus, doubling the dose of alemtuzumab to 60 mg did not provide equivalent prevention of GVHD after MUD transplant although there was no difference in non-relapse mortality or survival compared with MRD transplants.

Preemptive DLI without withdrawal of immunosuppression to promote complete donor T-cell chimerism results in favorable outcomes for high-risk older recipients of alemtuzumab-containing reduced-intensity unrelated donor allogeneic transplant: a prospective phase II trial

Although pretransplant alemtuzumab can reduce GVHD following allogeneic transplantation, it may also increase the risk of mixed donor T-cell chimerism and infections. We hypothesized that the early use of DLI without withdrawal of immunosuppressive drugs in patients with mixed T-cell chimerism would lower the risk of relapse without significantly increasing the risk of GVHD post DLI. Thirty-six patients (median age 59 years) were treated in this phase II trial using reduced-intensity conditioning including s.c. alemtuzumab (total dose 43 mg) and a PBSC graft from a matched unrelated donor (UD). DLI without withdrawal of immunosuppressive drugs was administered to all 25 patients with <50% donor T-cell chimerism on day +60. The cumulative risks of acute and chronic GVHD were 42% and 59%, respectively. Estimated probabilities of non-relapse mortality (NRM) at day 100 and 1 year were 3% and 14%, respectively. With a median follow up 2.4 years, estimated survivals at day 100, 1 and 2 years were 97%, 71% and 57%, respectively. In multivariate analysis, the occurrence of acute GVHD was associated with an increased risk of mortality, whereas the occurrence of chronic GVHD had a protective effect, associated with decreased relapse and improved disease-free survival. Low-dose alemtuzumab and preemptive DLI provides favorable transplant outcomes including low NRM in an older patient population with high-risk malignancies undergoing UD transplantation.

Treatment of graft-versus-host disease with monoclonal antibodies and related fusion proteins

Allogeneic hematopoietic stem cell transplantation has evolved from an experimental treatment approach to a widely used, curative therapy to treat malignant and nonmalignant diseases of the hematopoietic system. Despite advances in donor selection, conditioning regimens and supportive care, acute and chronic graft-versus-host disease (GvHD) remain a major cause of morbidity and mortality. Steroids are the standard first-line treatment and are able to control GvHD in approximately 50% of patients. Those who fail on steroids have a poor long-term prognosis. Therefore, a large number of drugs and procedures have been evaluated as second-line therapy. Monoclonal antibodies have increasingly been used to treat malignancy and autoimmune disease during the last 20 years. Their unique ability to target specific antigens theoretically enables them to directly interfere with cellular mechanisms that are involved in GvHD pathology. For this reason, monoclonal antibodies have been studied extensively as a second-line treatment for acute and chronic GvHD. The purpose of this article is to collect published data on clinical trials from the current literature and to give an overview on efficacy and toxicity of monoclonal antibody treatment for GvHD.

Allogeneic immunotherapy to optimize the graft-versus-tumor effect: concepts and controversies

This article focuses on the recent evolution of novel conditioning regimens in combination with adoptive cellular therapy in the allogeneic transplant setting for hematologic malignancies. Building on data from animal models, the field of allogeneic transplantation is undergoing a paradigm shift toward immunosuppressive regimens with less toxicity that allow donor hematopoietic engraftment in order to provide a graft-versus-tumor effect as the primary goal of transplantation, rather than chemoablation. In addition, the strategies described in this article, including the use of T-cell subsets as adoptive therapy, will apply to a much broader pool of patients than traditional transplant approaches, thereby allowing more patients with life-limiting illnesses, previously deemed ineligible, to pursue therapy with curative intent.

Alemtuzumab for the prevention and treatment of graft-versus-host disease

Alemtuzumab is a humanized monoclonal antibody against the CD52 antigen, which is expressed on the surface of various hematopoietic cells such as B and T lymphocytes, and has been widely used for preventing acute graft-versus-host disease (GVHD) in allogeneic stem cell transplantation (SCT). Administration of 100 mg alemtuzumab before transplantation has resulted in a low incidence of acute GVHD in HLA-matched and mismatched transplantation from either related or unrelated donors. However, because alemtuzumab could remain in the blood at the lympholytic level 1-2 months after transplantation, immune reconstitution was substantially delayed, leading to a high incidence of viral infection and relapse. A dose reduction of alemtuzumab was attempted in a reduced-intensity conditioning setting to facilitate immune reconstitution, and this resulted in earlier immune reconstitution, but the clinical benefits were unclear. The dose of alemtuzumab and the timing of its administration should be optimized to maximize the benefit of acute GVHD suppression and minimize the risk of infection and relapse. Another strategy to facilitate immune reconstitution and augment anti-tumor effects is donor cell infusion of T and NK cells. Although there is accumulating evidence regarding the use of alemtuzumab for acute GVHD prevention, information on the salvage treatment for steroid-refractory acute and chronic GVHD is still limited.

Pharmacokinetics and clinical activity of very low-dose alemtuzumab in transplantation for acute leukemia

The optimal dose of in vivo-administrated alemtuzumab in the allogeneic transplantation setting has not been defined. We report our experience on 37 patients with high-risk diseases, mainly acute leukemia (AML 23, ALL 10 patients), who underwent sibling (49%) or unrelated (51%) PBSCT (35 patients), and received a total dose of only 10-20 mg Campath-1H as part of the conditioning, and post-transplant CYA without MTX. The neutrophil and especially the platelet engraftment were rapid. There were only two grade III-IV acute GvHD cases, which occurred in unrelated transplants in the Campath-10 cohort. Chronic GvHD developed in six cases (17%) and was limited to skin in five of them. After a median follow-up of 371 days (59-1191), 70% patients are alive and in CR (Karnofsky 100%), and 11 died (TRM n=6, relapse n=5). From the five patients relapsed, three were at advanced stage at transplant and four underwent sibling HCT with the higher (20 mg) alemtuzumab dose. With the 10 mg alemtuzumab schedule (5 mg/day at days -2 and -1) we achieve at day of transplantation low but still lymphotoxic alemtuzumab serum concentrations (176 ng/mL), whereas levels declined fast thereafter, and at engraftment nearly no Campath antibody remained in the patient's serum.

Tackling mantle cell lymphoma (MCL): Potential benefit of allogeneic stem cell transplantation

Mantle cell lymphoma (MCL) is a type of non-Hodgkins lymphoma (NHL) associated with poor progression-free and overall survival. There is a high relapse rate with conventional cytotoxic chemotherapy. Intensive combination chemotherapy including rituximab, dose intense CHOP- (cyclophosphamide-doxorubicin-vincristine-prednisone) like regimens, high dose cytarabine, and/or consolidation with autologous stem cell transplant (autoSCT) have shown promise in significantly prolonging remissions. Data from phase II studies show that even in patients with chemotherapy refractory MCL, allogeneic stem cell transplant (alloSCT) can lead to long term disease control. Most patients with MCL are not candidates for myeloablative alloSCT due to their age, comorbidities, and performance status. The advent of less toxic reduced intensity conditioning (RIC) regimens, which rely more on the graft-versus-lymphoma (GVL) effect, have expanded the population of patients who would be eligible for alloSCT. RIC regimens alter the balance of toxicity and efficacy favoring its use. Treatment decisions are complicated by introduction of novel agents which are attractive options for older, frail patients. Further studies are needed to determine the role and timing of alloSCT in MCL. Currently, for selected fit patients with chemotherapy resistant MCL or those who progress after autoSCT, alloSCT may provide long term survival.

A novel GVHD-prophylaxis with low-dose alemtuzumab in allogeneic sibling or unrelated donor hematopoetic cell transplantation: the feasibility of deescalation

Prophylaxis of acute graft-versus-host disease (aGVHD), while maintaining the graft-versus-leukemia (GVL)/lymphoma effect and preventing severe infectious diseases, remains the main challenge in allogeneic hematopoetic cell transplantation (allo-HCT). To evaluate this, we examined the feasibility of deescalating the dose of alemtuzumab (MabCampath) in combination with cyclosporine (CsA) as the sole GVHD-prophylaxis in patients after fludarabine (Flu)-based reduced-intensity conditioning (RIC) in an observational cohort study. We included 127 consecutive patients (median age 63 years) with an unrelated (UD; n=69) or related donor (SIB; n=58) after their first transplantation, mostly presenting with advanced disease. The first 30 patients received 20 mg/day on day -2 and -1 (40 mg), the following 48 patients 10 mg/day on day -2 and -1 (20 mg), and the last 49 patients 10 mg on day -1 (10 mg) alemtuzumab intravenous (i.v.) prior to transplant. We observed no statistical differences comparing the 40 mg, 20 mg, or 10 mg dose groups, in terms of cumulative incidences of aGVHD grade III-IV 7% (confidence interval [CI] 95%; 1-51), 12% (1-40), 6% (1-40), extensive chronic GVHD (cGVHD) 24.4% (3.3-55.8), 17% (2.5-42), and 14.2% (1.5-41.5) and of aGVHD grade II-IV 7 % (0-51.5), 29% (11.9-49.1), 21% (15.3-43.1), respectively. The difference between the 20-mg and 40-mg groups was significant for aGVHD grade II-IV(P < .05). In conclusion, we demonstrate the feasibility of reducing the dose of alemtuzumab as GVHD-prophylaxis to 10 mg absolute in combination with CsA only for UD transplantation in particular.

Alemtuzumab for the treatment of steroid-refractory acute graft-versus-host disease

The treatment of steroid-refractory acute graft-versus-host disease (aGVHD) remains a clinical challenge, for which no standard therapy exists. Alemtuzumab is a humanized anti-CD52 monoclonal antibody (mAb) that has been successfully used as part of conditioning regimens for hematopoietic stem cell transplantation (HSCT) to prevent GVHD. The purpose of this study was to evaluate the safety and efficacy of alemtuzumab in treating steroid-refractory aGVHD (>or=grade II) following HSCT. Eighteen patients received subcutaneous alemtuzumab 10 mg daily on 5 consecutive days. Response was assessed at day 28 following initiation of alemtuzumab. Eight patients had grade II aGVHD, 8 had grade III, and 2 had grade IV. The main organ involved was the liver in 4 patients, gastrointestinal (GI) tract in 5, skin in 3, skin and liver in 3, and skin and GI tract in 3. Fifteen patients (83%) responded to alemtuzumab, including 6 (33%) with complete response. All 3 unresponsive patients died of GVHD. Ten of 15 responders are alive at median follow-up of 11 months (range: 3-24). Infections occurred in 14 patients, including cytomegalovirus (CMV) reactivation in 11. Grade 3 neutropenia and thrombocytopenia occurred in 6 and 4 patients, respectively. Alemtuzumab was well tolerated, and induces promising response rates in steroid-refractory aGVHD.

A new sensitive enzyme-linked immunosorbent assay (ELISA) for Alemtuzumab determination: development, validation and application

Alemtuzumab is a humanized (IgG(1)) rat monoclonal antibody to CD52 antigen and is currently used in the treatment of chronic lymphocytic leukemia (CLL) and other CD52-positive lymphoproliferative disorders. Various techniques have been developed to measure Alemtuzumab levels in human serum/plasma. The authors report on the validation of a very sensitive enzyme-linked immunosorbent assay (ELISA) to measure serum concentrations of the humanized IgG(1) using a rabbit polyclonal antibody specifically produced against the rat sequence of Alemtuzumab after papain digestion. The assay was successfully applied to test the serum samples of patients with B-lymphocyte CLL who received Alemtuzumab subcutaneously. This ELISA assay could be easily used to determine human serum levels of Alemtuzumab pre- and post-treatment to optimize dosing and scheduling and to study the relationship between dose and clinical response.

Tailored strategy for AML patients receiving allogeneic peripheral blood stem cell transplantation

Considering the heterogeneity of acute myelogenous leukemia (AML), along with the pros and cons of allogeneic peripheral blood stem cell transplantation (PBSCT), a tailored strategy is needed to minimize the transplant-related mortality and maximize the transplant outcomes in AML patients exhibiting certain factors that have an impact on the post-transplant quality of life and outcomes. The factors that need to be considered when tailoring a strategy in an allogeneic PBSCT setting include the recipient's performance status and co-morbid disease include AML risk stratification, disease status, expected severity of graft-versus-host disease, and the necessity of a graft-versus-leukemia effect. Accordingly, this review article describes a possible tailoring strategy for AML patients receiving allogeneic PBSCT based on certain factors influencing the transplant outcome.

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.

Stem cell transplantation with reduced-intensity conditioning regimens: a review of ten years experience with new transplant concepts and new therapeutic agents

The realization in the 1990s that allogeneic stem cell transplants (SCT) have a potentially curative graft-versus-leukemia (GVL) effect in addition to the antileukemic action of myeloablative conditioning regimens was a major stimulus for the development of reduced-intensity conditioning (RIC) regimens, aimed primarily at securing engraftment to provide the GVL effect, while minimizing regimen-related toxicity. It is now over 10 years since RIC regimens were heralded as a new direction in the field of SCT. Over the last decade much has been learned about the ways in which the conditioning regimen can be tailored to provide adequate immunosuppression, and modulated to deliver a chosen degree of antimalignant treatment. The huge literature of clinical data with RIC transplantation now permits us to more clearly define the success and limitations of the approach. This review examines the origins of RIC SCT, explores the degree to which the initial expectations and purpose of the approach have been realized, and outlines some ways forward for the field.

The Role of Alemtuzumab in Nonmyeloablative Hematopoietic Transplantation

Nonmyeloablative stem cell transplants provide a viable therapeutic option for older patients or patients with comorbid conditions, who were previously deemed to be ineligible for transplantation. Despite improvements in clinical outcomes, graft-versus-host disease (GVHD) remains a significant and potentially lethal complication. One approach by which GVHD has been managed is through introduction of new agents, such as alemtuzumab, into the conditioning regimen. Alemtuzumab is a humanized monoclonal antibody that targets the CD52 antigen, which is highly expressed on both B and T lymphocytes. By depleting T cells in both the donor and the recipient, alemtuzumab has been shown to prevent development of both acute and chronic GVHD, without inhibiting the benefits associated with the graft-versus-leukemia effect. Clinical trials have shown that alemtuzumab is able to decrease the incidence of acute and chronic GVHD without impairing engraftment. Furthermore, in chronic lymphocytic leukemia therapy, alemtuzumab has been shown to purge malignant cells from the host to allow for harvesting for the purpose of autologous transplantation. Despite results showing that alemtuzumab can play an important role in managing GVHD, little information is available regarding a standardized dosing schedule. Greater insight into alemtuzumab's pharmacokinetic activity would assist in developing a schedule that can optimize alemtuzumab-mediated T-cell depletion to prevent GVHD, while retaining sufficient host T-cell activity to encourage the graft-versus-leukemia effect and prevent relapse.

Myeloablative allogeneic hematopoietic stem cell transplantation in elderly patients

This study aimed to evaluate the outcome following myeloablative allogeneic hematopoietic stem cell transplantation (SCT) among patients older than 50 yr of age. A total of 215 patients with a median age of 57 yr underwent allogeneic hematopoietic SCT for early (41%) or advanced (59%) hematologic malignancies. After a median follow-up of 36 months a 10-yr survival estimate of 56 +/- 6% could be assessed for patients in early disease stages while patients with advanced diseases showed a significantly decreased survival probability of 31 +/- 5% (p < 0.0002). Transplant related mortality (TRM) at day 100 and 365 post-transplant was 13% and 30% for early but increased to 21% and 49% for advanced disease stages. As major determinants of TRM advanced disease stage (p < 0.0001) and occurrence of grades II-IV graft-vs.-host disease (GVHD) (p < 0.0001) were identified. These results show that hematopoietic SCT following myeloablative conditioning is also applicable to elderly patients whereas disease stage and high-grade GVHD represent the essential prognostic factors for outcome.

Exogenous administration of immunomodulatory therapies in hematopoietic cell transplantation: an infectious diseases perspective

PURPOSE OF REVIEW

In contrast to the recipient of a solid organ transplantation, the immunological competence of recipients of hematopoietic cell transplantation does not correlate well with the administration of non-corticosteroid immunosuppressive agents. This apparent paradox reflects the unique and dynamic conglomeration of factors that affect immune reconstitution after hematopoietic cell transplantation. The following is the second part of a review of the recent primary literature regarding exogenous immunomodulatory influences as they pertain to infections in the setting of hematopoietic cell transplantation.

RECENT FINDINGS

The main themes of published primary research from 2004 to the present include the influence of exogenously administered immunomodulatory agents on infectious complications after hematopoietic cell transplantation.

SUMMARY

The use of immunomodulatory agents such as monoclonal antibodies directed against lymphocyte antigens in the treatment of hematopoietic malignancy has greatly expanded during the past decade. Separate trials of the potential utility of these agents, particularly in the reduction of graft-versus-host disease, in the setting of hematopoietic cell transplantation have yielded encouraging results. Given the infancy of these new approaches, it is not possible to make definitive statements regarding the relative risk of serious infection with each therapy. It is clear that a reduction in regimen-related non-infectious complications or mortality does not necessarily ensure a reduction in clinically significant infections. Improvements in early diagnostic and therapeutic options for these infections now bring us to an era of understanding pathogens such as cytomegalovirus as probes of the functional reconstitution of immunity.

The role of allogeneic transplantation in non-Hodgkin's lymphoma

The evolution of combination chemotherapy regimens, combined with improvements in supportive care, has incrementally improved survival outcomes for patients with non-Hodgkin's lymphomas (NHL). Although 40-60% of younger patients with diffuse large cell lymphoma can now expect to be cured, significant numbers will either fail to achieve a remission or relapse after attaining a remission. In addition, certain histological subtypes are associated with particularly poor prognoses with combination chemotherapy alone (e.g. mantle cell lymphoma, B-cell prolymphocytic leukaemia). Relatively few of these patients can achieve long-term responses. Other NHL subtypes, whilst associated with more favourable prognoses in terms of overall survival, are rarely, if ever, cured (e.g. most low grade NHL including follicular lymphoma, chronic lymphocytic leukaemia and small lymphocytic lymphoma). For these reasons dose escalation and allogeneic transplantation have been investigated as potential ways of improving outcome, although this has mainly been in the setting of advanced disease. Any possible benefits have frequently been out-weighed by procedural morbidity and mortality. The parallel development of transplantation approaches that limit procedural toxicity along with advances in supportive care require that the role of allogeneic haematopoietic stem cell transplantation in the management of lymphoma be re-evaluated.