Management of chronic myeloid leukaemia in relapse following donor lymphocyte infusion induced remission: a retrospective study of the clinical trials committee of the British Society of Blood & Marrow Transplantation (BSBMT)

At The Bedside: Clinical review of chimeric antigen receptor (CAR) T cell therapy for B cell malignancies

T cells kill microbial-infected and malignant cells by detection of nonself antigens with the TCR. Tumor reactivity can be encoded genetically by introducing a chimeric antigen receptor (CAR) into T cells. CARs are composed of an antigen-binding domain and an intracellular T cell activation domain. Early human trials evaluating CD19-targeted CAR T cells for chronic lymphocytic leukemia (CLL) showed limited responses until CARs included a costimulation domain, and conditioning chemotherapy was given before T cell infusion. Clinical trials evaluating CD19-targeted CAR T cells for B cell acute lymphoblastic leukemia (B-ALL) are demonstrating response rates up to 90%. However, these clinical outcomes are associated with a cytokine release syndrome (CRS), which is caused by T cell activation and manifests as high-grade fever, hypotension, and other cardiovascular complications. It is currently managed conservatively but can be treated with cytokine-directed therapy or with high-dose steroids. Current efforts are dedicated to confirming the clinical efficacy and managing toxicities in multicenter Phase II trials. We present a thorough overview of the preclinical and clinical development of CAR T cell therapy that will highlight important areas for the basic researcher to investigate in the laboratory and contribute to this exciting field.

Molecular monitoring of BCR-ABL transcripts after allogeneic stem cell transplantation for chronic myeloid leukemia

The monitoring of minimal residual disease (MRD) through low sensitivity real-time (RT) polymerase chain reaction (PCR) analysis of BCR-ABL transcripts allows early detection of chronic myeloid leukemia (CML) relapse after allogeneic hematopoietic stem cell transplantation (HSCT). The introduction of more sensitive techniques, such as RT quantitative (Q)-PCR, may lead to an overestimation of the risk of CML relapse. In this study, we reviewed the results of peripheral blood RT Q-PCR in CML patients who underwent allogeneic HSCT from 1983 to 2007. In our laboratory, RT Q-PCR analysis was routinely performed since 2002. Eighty-seven of 189 patients had available RT Q-PCR data; 63 patients had at least 3 RT Q-PCR analyses assessable. Fifty-two of 63 patients (83%) had, at least once, detectable transcript levels, but with an BCR-ABL/ABL ratio <.1% defined as <MR3 (molecular remission <0,1%), whereas 11 (17%) had persistent undetectable BCR-ABL transcripts. Six of 52 patients with <MR3 relapsed, defined as BCR-ABL transcript numbers >.1% confirmed by the finding of Ph+ cells in bone marrow. No patients with persistent undetectable transcripts relapsed (P = .19). Relapse did not correlate with the number of occurrences of <MR3 or with the time to the first <MR3 result. Finally, of 46 patients with detectable transcripts who did not relapse, 35 had undetectable transcripts at last contact. RT Q-PCR analysis had low specificity (19%) and low positive predictive value (12%) in predicting relapse of CML patients after allogeneic HSCT. Our data suggest that detection of low BCR-ABL transcript levels by RT Q-PCR analysis has a poor accuracy in defining the risk of CML relapse and should not be considered as the unique indication to treatment. Fluctuation of BCR-ABL transcripts levels is common as late as ≥10 years posttransplantation, possibly suggesting the long-term persistence of CML stem cells.

Allogeneic stem cell transplantation for patients with chronic myeloid leukemia: risk stratified approach with a long-term follow-up

The use of allogeneic stem cell transplantation (SCT) for chronic myeloid leukemia (CML) was almost abandoned in recent years for very effective targeted therapy with tyrosine kinase inhibitors (TKIs). However, approximately one third of patients still need another treatment including SCT. 38 consecutive CML patients were treated (most in preimatinib era) with allogeneic SCT, using partial T cell depletion (TCD) and preemptive donor lymphocyte infusion (DLI), without post-transplant graft-versus-host disease (GvHD) prophylaxis. Conditioning included busulfan, cyclophosphamide, antithymocytic globulin, and fludarabine followed by donor stem cell transfusion. With a median follow up of 90.5 months (1-134), 32 patients are alive. 97% engrafted. 5-year leukemia free survival (LFS) and overall survival (OS) were 78.95% and 84.2%, respectively. All patients are in major molecular remission and 78% in complete molecular remission. Transplant-related mortality (TRM) was 13%. Twenty-four patients received DLI for residual disease. Acute GvHD, mostly Grades I-II, occurred in 18% of patients post-transplant and in 24% of patients receiving DLI. In conclusion, the risk-adapted approach using only partial TCD and preemptive escalated dose of DLI precluded the need for immunosuppressive medications and reduced the risk of significant GvHD without compromising engraftment and long-term disease control. Am. J. Hematol. 2012. © 2012 Wiley Periodicals, Inc.

Cancer immunotherapy

Cancer immunotherapy consists of approaches that modify the host immune system, and/or the utilization of components of the immune system, as cancer treatment. During the past 25 years, 17 immunologic products have received regulatory approval based on anticancer activity as single agents and/or in combination with chemotherapy. These include the nonspecific immune stimulants BCG and levamisole; the cytokines interferon-α and interleukin-2; the monoclonal antibodies rituximab, ofatumumab, alemtuzumab, trastuzumab, bevacizumab, cetuximab, and panitumumab; the radiolabeled antibodies Y-90 ibritumomab tiuxetan and I-131 tositumomab; the immunotoxins denileukin diftitox and gemtuzumab ozogamicin; nonmyeloablative allogeneic transplants with donor lymphocyte infusions; and the anti-prostate cancer cell-based therapy sipuleucel-T. All but two of these products are still regularly used to treat various B- and T-cell malignancies, and numerous solid tumors, including breast, lung, colorectal, prostate, melanoma, kidney, glioblastoma, bladder, and head and neck. Positive randomized trials have recently been reported for idiotype vaccines in lymphoma and a peptide vaccine in melanoma. The anti-CTLA-4 monoclonal antibody ipilumumab, which blocks regulatory T-cells, is expected to receive regulatory approval in the near future, based on a randomized trial in melanoma. As the fourth modality of cancer treatment, biotherapy/immunotherapy is an increasingly important component of the anticancer armamentarium.

Donor lymphocyte infusion following allogeneic hematopoietic stem cell transplantation

INTRODUCTION

Allogeneic hematopoietic stem cell transplantation (SCT) is the treatment of choice for many malignant hematological disorders. Following recent improvements in non-relapse-related mortality rates, relapse has become the commonest cause of treatment failure. Infusion of donor lymphocytes can potentially enhance immune-mediated antitumor activity and offers a salvage option for some patients. This paper reviews the current literature on the efficacy of this therapeutic strategy.

AREAS COVERED

The biology of adoptive cellular therapy with allogeneic immune cells to treat relapse across a spectrum of diseases in both the full intensity and reduced intensity hematopoietic SCT settings is explored. The review discusses the current limitations of the approach and reviews several new experimental strategies which aim to segregate the desired graft-versus-tumor effect from the deleterious effects of more widespread graft-versus-host reactivity.

EXPERT OPINION

Durable responses to DLI have been noted in chronic myeloid leukemia and responses have also been described in acute leukemia, multiple myeloma and chronic lymphoproliferative disorders. The new challenge in transplantation is to optimize DLI therapy in order to further improve patient outcomes.

Recent advances in quantitative chimerism analysis

Quantitative chimerism analysis is a diagnostic tool used to monitor engraftment kinetics after allogeneic stem cell transplantation. It reflects the proportion of recipient and donor genotypes and is based on the identification of genetic markers characteristic to a given transplant pair. Currently, PCR amplification of short tandem repeats and single-nucleotide polymorphism-specific quantitative real-time PCR are the most widely used techniques for this purpose. In this review, we will address advances as well as technology-specific imperfections, of both techniques that have emerged over the recent years. We will discuss new principles that may simplify assay design, and improve its robustness and reliability. A better chimerism assay could then guide clinical interventions and may, eventually, improve the outcome of allogeneic stem cell transplantation.

Graft-versus-leukemia effects of transplantation and donor lymphocytes

Allogeneic transplantation of hematopoietic cells is an effective treatment of leukemia, even in advanced stages. Allogeneic lymphocytes produce a strong graft-versus-leukemia (GVL) effect, but the beneficial effect is limited by graft-versus-host disease (GVHD). Depletion of T cells abrogates GVHD and GVL effects. Delayed transfusion of donor lymphocytes into chimeras after T cell-depleted stem cell transplantation produces a GVL effect without necessarily producing GVHD. Chimerism and tolerance provide a platform for immunotherapy using donor lymphocytes. The allogeneic GVL effects vary from one disease to another, the stage of the disease, donor histocompatibility, the degree of chimerism, and additional treatment. Immunosuppressive therapy before donor lymphocyte transfusions may augment the effect as well as concomitant cytokine treatment. Possible target antigens are histocompatibility antigens and tumor-associated antigens. Immune escape of tumor cells and changes in the reactivity of T cells are to be considered. Durable responses may be the result of the elimination of leukemia stem cells or the establishment of a durable immune control on their progeny. Recently, we have learned from adoptive immunotherapy of viral diseases and HLA-haploidentical stem cell transplantation that T-cell memory may be essential for the effective treatment of leukemia and other malignancies.

Disease relapse after haematopoietic stem cell transplantation: Risk factors and treatment

Disease relapse is the commonest cause of treatment failure after allogeneic haematopoietic stem-cell transplantation. Adoptive immunotherapy based on donor lymphocyte infusions (DLI) has a prominent role in the management of disease recurrence. Although the highest remission rates are achieved in chronic myeloid leukaemia (CML), encouraging results have also been reported in chronic lymphoproliferative disorders. However, the experience of DLI in CML is not necessarily applicable to the management of lymphoproliferative diseases because of the heterogeneity of the conditioning regimens used in chronic lymphoid malignancies. We will review the role of DLI for different disease types in the context of conventional and reduced-intensity conditioning regimens. The factors influencing response and graft-versus-host disease as well as the optimal cell dose will be discussed. Finally, we will describe the main avenues currently being explored to improve the selectivity and efficacy of DLI.