Managing the Patient with Chronic Myeloid Leukemia Through and After Allogeneic Stem Cell Transplantation

Graft-versus-Leukemia Effect Following Hematopoietic Stem Cell Transplantation for Leukemia

The success of hematopoietic stem cell transplantation (HSCT) lies with the ability of the engrafting immune system to remove residual leukemia cells via a graft-versus-leukemia effect (GvL), caused either spontaneously post-HSCT or via donor lymphocyte infusion. GvL effects can also be initiated by allogenic mismatched natural killer cells, antigen-specific T cells, and activated dendritic cells of leukemic origin. The history and further application of this GvL effect and the main mechanisms will be discussed and reviewed in this chapter.

Donor Lymphocyte Infusions for Chronic Myeloid Leukemia Relapsing after Allogeneic Stem Cell Transplantation: May We Predict Graft-versus-Leukemia Without Graft-versus-Host Disease?

Donor lymphocyte infusions (DLI) are an effective treatment for relapsed chronic myeloid leukemia (CML) after allogeneic stem cell transplantation (alloSCT). Leukemia resistance and secondary graft-versus-host disease (GVHD) are major obstacles to success with DLI. The aim of this study was to identify pre-DLI factors associated with prolonged survival in remission without secondary GVHD. We retrospectively analyzed 500 patients treated with DLI for CML relapse (16% molecular, 30% cytogenetic, and 54% hematological) after alloSCT. The overall probabilities of failure- and secondary GVHD-free survival (FGFS) were 29% and 27% at 5 and 10 years after DLI, respectively. The type of relapse was the major factor influencing FGFS (40% for molecular and/or cytogenetic relapse and 20% for hematological relapse at 5 years, P < .001). Chronic GVHD before DLI and an interval <1 year between alloSCT and first DLI were independently associated with inferior FGFS in patients with molecular and/or cytogenetic relapse. Consequently, FGFS was 13%, 35%, to 56% at 5 years in patients with 2, 1, and 0 adverse features, respectively. In patients with hematological relapse, independent adverse prognostic factors for FGFS were initial dose of CD3(+) cells ≥ 50 × 10(6)/kg, donor-recipient sex mismatch, and chronic GVHD before DLI. FGFS was 0%, 17%, 33%, to 37% in patients with 3, 2, 1, and 0 adverse features, respectively. The probability of survival in remission without secondary GVHD was highest (>50% at 5 years) when DLI were given beyond 1 year from alloSCT for molecular and/or cytogenetic CML relapse that was not preceded by chronic GVHD.

A comparison of long-term outcomes of donor lymphocyte infusions and tyrosine kinase inhibitors in patients with relapsed CML after allogeneic hematopoietic cell transplantation

BACKGROUND

Donor lymphocyte infusion (DLI) and tyrosine kinase inhibitors (TKIs) are the 2 standard treatment options in chronic myeloid leukemia (CML) that relapses after hematopoietic cell transplantation (HCT), but reports comparing long-term outcomes of these modalities are rare.

PATIENTS AND METHODS

A total of 46 patients were treated with either DLI (n = 28) or TKIs (n = 18) during a first relapse of CML after HCT between 1993 and 2012. The stage of relapse was the chronic phase in 37 patients and the advanced phase in 9 patients. All patients had myeloablative conditioning without T-cell depletion during HCT. The median interval between HCT and treatment for relapse was 34 (range, 2-197) months.

RESULTS

At a median follow-up of 146 and 70 months, respectively, 32% of the DLI group and 33% of the TKI group had died. Six (21%) patients initially treated with DLI received TKIs during a second relapse. In multivariable analyses, DLI was associated with inferior overall survival (OS) (hazard ratio [HR], 37.4; 95% confidence interval [CI], 2.2-625.4; P = .01), shorter failure-free survival (FFS) (HR, 21.15; 95% CI, 1.8-251; P = .02), higher cumulative incidence of failure (CIF) (HR, 19.5; 95% CI, 1.6-236.5; P = .02), and increased incidence of treatment-induced graft vs. host disease (GVHD) (68% vs. 6%; P = .001).

CONCLUSION

TKIs appear better than DLI in chronic-phase relapses after myeloablative non-T-cell-depleted HCT. Outcomes were poor in advanced-phase relapses irrespective of treatment modality.

Monitoring response and resistance to treatment in chronic myeloid leukemia

Chronic myeloid leukemia (cml) results from expression of the constitutive tyrosine kinase activity of the Bcr-Abl oncoprotein. Imatinib, a tyrosine kinase inhibitor (tki), is highly effective in the treatment of cml. However, some patients treated with imatinib will fail to respond, will respond suboptimally, or will relapse because of primary or acquired resistance or intolerance. Research activities focusing on the mechanisms that underlie imatinib resistance have identified mutations in the BCR-ABL gene, clonal evolution, and amplification of the BCR-ABL gene as common causes. Cytogenetic and molecular techniques are currently used to monitor cml therapy for both response and relapse. With multiple and more potent therapeutic options now available, monitoring techniques can permit treatment to be tailored to the individual patient based on disease characteristics-for example, according to BCR-ABL mutation profile or to patient characteristics such as certain comorbid conditions. This approach should benefit patients by increasing the potential for better long-term outcomes.

Late mortality and relapse following BuCy2 and HLA-identical sibling marrow transplantation for chronic myelogenous leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only known curative therapy for chronic myelogenous leukemia (CML). Failure, because of relapse or nonrelapse mortality (NRM), generally occurs within 3 years of transplantation, but large studies with long-term follow-up are limited. We present mature results in 335 patients with CML who underwent allogeneic bone marrow transplantation (BMT) from HLA-identical siblings following busulfan and cyclophosphamide (BU/Cy2). Two hundred twenty-nine were in chronic phase (CP) and 106 in accelerated or blastic phase at transplantation. Median follow-up exceeded 14 years. The estimated probability of 18-year leukemia-free survival (LFS) for CP patients was 55.6% and for those beyond CP, 10.5%. Of 182 patients who survived leukemia-free at 3 years, the estimated probability of LFS at 18 years was 61.9%. Late relapse (P = .039) and late NRM (P = .008) occurred at higher rates in patients beyond CP at transplantation. There was no plateau in LFS.

Minimal residual disease diagnostics in myeloid malignancies in the post transplant period

Allogeneic SCT is important in myelodysplastic syndrome, the BCR-ABL-negative chronic myeloproliferative diseases (CMPDs) and in poor-risk AML. Techniques to monitor the minimal residual disease, for example, by PCR or immunophenotyping gain increasing importance in the post transplantation period as basis for improved and earlier therapeutic interventions in impending relapse. Recent markers such as the NPM1 mutations in AML or the JAK2V617F mutation in the CMPD can be exactly quantified by real-time PCR and were evaluated for their prognostic value in the post transplantation phase and for their utility to plan adoptive immunotherapy in case of molecular relapse. With respect to chimerism, new and very sensitive methods were introduced, for example, quantitative assessment of genetic polymorphisms by real-time PCR, but also methods here are still highly individualized. Only in CML, where SCT focuses now on poor-risk cases or cases of tyrosine kinase inhibitor failure, follow-up schedules are standardized. Standardization of the different diagnostic techniques and of the intervals in the post transplantation period is urgently needed also in other myeloid malignancies and should be focus of future studies.

Chronic myeloid leukaemia as a model of disease evolution in human cancer

Chronic myeloid leukaemia (CML) can be considered as a paradigm for neoplasias that evolve through a multi-step process. CML is also one of the best examples of a disease that can be targeted by molecular therapy; however, the success of new 'designer drugs' is largely restricted to the chronic phase of the disease. If not cured at this stage, CML invariably progresses and transforms into an acute-type leukaemia undergoing a 'blast crisis'. The causes of this transformation are still poorly understood. What mechanisms underlie this progression, and are they shared by other common cancers?