DLI: Where are we know?

New cell sources for T cell engineering and adoptive immunotherapy

The promising clinical results obtained with engineered T cells, including chimeric antigen receptor (CAR) therapy, call for further advancements to facilitate and broaden their applicability. One potentially beneficial innovation is to exploit new T cell sources that reduce the need for autologous cell manufacturing and enable cell transfer across histocompatibility barriers. Here we review emerging T cell engineering approaches that utilize alternative T cell sources, which include virus-specific or T cell receptor-less allogeneic T cells, expanded lymphoid progenitors, and induced pluripotent stem cell (iPSC)-derived T lymphocytes. The latter offer the prospect for true off-the-shelf, genetically enhanced, histocompatible cell therapy products.

Chronic myeloid leukemia: a historical perspective

Patients with splenomegaly and abnormally high leukocyte counts were first recognized in France, Germany, and Scotland in the 1840s. The only well-documented therapy in the 19th century was use of arsenic in one or other form, which did undoubtedly reduce the leukocyte count but probably did little or nothing to prolong life. These early cases were probably examples of chronic myeloid leukemia (CML) (then called chronic granulocytic leukemia). In the 20th century important steps in unraveling the pathogenesis of CML were the discovery of the Philadelphia chromosome in 1960, and of the (9;22) translocation in 1973. There followed definition of the breakpoint cluster region on chromosome 22 in 1984 and the demonstration of the BCR-ABL transcript in CML in 1985. In the first half of the 20th century patients were treated predominantly with radiotherapy, and later on with busulfan, hydroxycarbamide, or interferon-alfa (IFN-α). From 1980 onwards allogeneic stem cell transplantation (SCT) became the treatment of choice for eligible patients. The era of tyrosine kinase inhibitors (TKI) began in 1998 and today the use of the original TKI, imatinib, has replaced SCT as initial therapy for patients who present with CML in chronic phase.

Outcome of 93 patients with relapse or progression following allogeneic hematopoietic cell transplantation

Relapse/progression after allogeneic hematopoietic cell transplantation (allo-HCT) remains the major cause of treatment failure. In this study, the subsequent clinical outcome was overviewed in 292 patients with leukemia/myelodysplastic syndrome who received allo-HCT. Among them, 93 (32%) showed relapse/progression. Cohort 1 was chosen to receive no interventions with curative intent (n = 25). Cohort 2 received reinduction chemotherapy and/or donor lymphocyte infusion (n = 48), and Cohort 3 underwent a second allo-HCT (n = 20). Sixty-three patients received reinduction chemotherapy, and 27 (43%) achieved subsequent complete remission (CR). The incidence of nonrelapse mortality (NRM) was similar among the three cohorts (4, 15, and 5%). The 1-year overall survival (OS) after relapse was significantly better in patients with a second HCT (58%) than in others (14%, Cohorts 1 and 2; P <.001). However, the 2-year OS did not differ between the two groups, which suggests that it is difficult to maintain CR after the second HCT. Multivariate analysis showed that reinduction chemotherapy, CR after intervention, second HCT, and longer time to post-transplant relapse were associated with improved survival. In conclusion, for patients with relapse after allo-HCT, successful reinduction chemotherapy and a second HCT may be effective for prolonging survival without excessive NRM. However, effective measures to prevent disease progression after a second HCT clearly need to be developed.

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.