Dasatinib enhances the expansion of CD56+CD3- NK cells from cord blood

NK92 cells and peripheral blood NK cells respond oppositely upon dasatinib treatment

Natural killer (NK) cell is a valuable tool for immunotherapy in cancer treatment, both the cultured cell line NK92 and primary NK cells are widely studied and used in research and clinical trials. Clinical observations witnessed the improvement of patients' NK cells in terms of cell counts and cytotoxic activity upon dasatinib treatment, an approved drug for chronic myeloid leukaemia and Ph+ acute lymphocytic leukaemia. Several studies supported the clinical observations, yet others argued a detrimental effect of dasatinib on NK cells. Due to the complex conditions in different studies, the definite influence of dasatinib on NK92 and primary NK cells remains to be settled. Here, we used a well-defined in vitro system to evaluate the effects of dasatinib on NK92 cells and peripheral blood (PB)-NK cells. By co-culturing NK cells with dasatinib to test the cell counts and target cell-killing activities, we surprisingly found that the chemical influenced oppositely on these two types of NK cells. While dasatinib suppressed NK92 cell proliferation and cytotoxic activity, it improved PB-NK-killing tumour cells. RNA sequencing analysis further supported this finding, uncovering several proliferating and cytotoxic pathways responding invertedly between them. Our results highlighted an intrinsic difference between NK92 and PB-NK cells and may build clues to understand how dasatinib interacts with NK cells in vivo.

Recent progress in and challenges in cellular therapy using NK cells for hematological malignancies

NK cells have killing activity against leukemic cells and solid cancer cells that escape from T cell recognition because of the low expression level of HLA class I molecules. This characteristic feature of NK cell recognition of target cells in contrast to T cells provides a strategy to overcome tolerance in cancer and leukemia patients. A strong alloreactive NK cell-mediated anti-leukemia effect can be induced in haploidentical hematopoietic stem cell transplantation. Also, NK cells can be expanded by several methods for adoptive immunotherapy for hematological malignancies and other malignant diseases. We review the historical role of NK cells and recent approaches to enhance the functions of NK cells, including ex vivo expansion of autologous and allogenic NK cells, checkpoint receptor blockade, and the use of memory-like NK cells and CAR-NK cells, for treatment of hematological malignancies.

Dasatinib-Induced T-Cell-Mediated Colitis: A Case Report and Review of the Literature

Dasatinib is a potent inhibitor of the altered tyrosine kinase activity in disease states associated with BCR/ABL1. This agent has been shown to exhibit broad off-target kinase inhibition and immunomodulating properties. These effects may be responsible for dasatinib's unique side effects including a distinctive form of hemorrhagic colitis. We report a case of hemorrhagic colitis associated with dasatinib use in a patient with chronic myelogenous leukemia. Colon biopsies at the time of symptomatic colitis confirmed CD3+CD8+ T cell infiltration. The process rapidly resolved following drug discontinuation, but relapsed when rechallenged with a reduced dose of dasatinib. Colitis did not recur when the patient was treated with an alternative agent. A literature review of prior cases involving dasatinib-induced T-cell mediated colitis provides insight into commonalities that may facilitate the recognition and management of this entity. Most incidences occurred after a 3-month drug exposure and may be accompanied by large granular lymphocytes. The process uniformly resolves within a few days following drug discontinuation and will generally recur in a shorter period of time if the drug is reintroduced. Most patients will require an alternative agent, although select patients could be continued on dasatinib if other options are limited.

Cellular engineering and therapy in combination with cord blood allografting in pediatric recipients

Cord blood (CB) transplantation is an alternate source of human hematopoietic progenitor cells for allogeneic stem cell transplantation in children and adolescents with both malignant and nonmalignant diseases. Current limitations included delay in hematopoietic reconstitution, increased incidence of primary graft failure and slow cellular immunoreconstitution. These limitations lead to a significant increase in primary graft failure, infectious complications and increased transplant-related mortality. There is a number of experimental approaches currently under investigation including cellular engineering to circumvent these limitations. In this review, we summarize the recent findings of utilizing ex vivo CB expansion with Notch1 ligand Delta 1, mesenchymal progenitor cells, the use of human placenta-derived stem cells and CB-derived natural killer cells. Early and preliminary results suggest some of these experimental cellular strategies may in part ameliorate the incidence of primary graft failure, delays in hematopoietic reconstitution and/or slowness in cellular immune reconstitution following unrelated CB transplantation.

Early cytotoxic lymphocyte expansion contributes to a deep molecular response to dasatinib in patients with newly diagnosed chronic myeloid leukemia in the chronic phase: results of the D-first study

Dasatinib is one of the key treatment options for chronic myeloid leukemia (CML) patients. Increase in lymphocyte counts has been known to be predictive of a good treatment response under dasatinib treatment as a second line therapy. However, clinical significance of lymphocyte dynamics in the upfront setting has yet to be clarified. To investigate the significance of lymphocyte dynamics in newly diagnosed chronic phase (CP)-CML, patient data of D-First study (ClinicalTrials.gov NCT01464411) were analyzed. Fifty-two CML-CP patients enrolled to this study were treated with dasatinib (100 mg day(-1) ) and all were followed-up for 18 months. The incidence of lymphocyosis was observed in 14 (27%), but it was not associated with deep molecular response achievement. However, natural killer (NK) cell or cytotoxic T lymphocyte (CTL) counts at 1 month were significantly higher in patients with deep molecular response (DMR) by 18 months compared to those without DMR. When the patients were divided into two groups according to those calculated thresholds by receiver operating characteristic curve (407/μL for NK cells and 347/μL for CTLs), the cumulative DMR rates by 18 months were significantly better in higher value group compared to lower value group. In contrast, regulatory T cell counts were significantly lower at 12 and 15 months in patients achieved DMR. These results suggest the presence of dual effects of dasatinib on immune system through the cytotoxic lymphocytes activation and Treg deregulation in different periods in newly diagnosed CML-CP.

Infusions of allogeneic natural killer cells as cancer therapy

Natural killer (NK) cells are normal white blood cells capable of killing malignant cells without prior sensitization. Allogeneic NK cell infusions are attractive for cancer therapy because of non-cross-resistant mechanisms of action and minimal overlapping toxicities with standard cancer treatments. Although NK therapy is promising, many obstacles will need to be overcome, including insufficient cell numbers, failure of homing to tumor sites, effector dysfunction, exhaustion, and tumor cell evasion. Capitalizing on the wealth of knowledge generated by recent NK cell biology studies and the advancements in biotechnology, substantial progress has been made recently in improving therapeutic efficiency and reducing side effects. A multipronged strategy is essential, including immunogenetic-based donor selection, refined NK cell bioprocessing, and novel augmentation techniques, to improve NK function and to reduce tumor resistance. Although data from clinical trials are currently limited primarily to hematologic malignancies, broader applications to a wide spectrum of adult and pediatric cancers are under way. The unique properties of human NK cells open up a new arena of novel cell-based immunotherapy against cancers that are resistant to contemporary therapies.

Improving engraftment and immune reconstitution in umbilical cord blood transplantation

Umbilical cord blood (UCB) is an important source of hematopoietic stem cells (HSC) for allogeneic transplantation when HLA-matched sibling and unrelated donors (MUD) are unavailable. Although the overall survival results for UCB transplantation are comparable to the results with MUD, UCB transplants are associated with slow engraftment, delayed immune reconstitution, and increased opportunistic infections. While this may be a consequence of the lower cell dose in UCB grafts, it also reflects the relative immaturity of cord blood. Furthermore, limited cell numbers and the non-availability of donor lymphocyte infusions currently prevent the use of post-transplant cellular immunotherapy to boost donor-derived immunity to treat infections, mixed chimerism, and disease relapse. To further develop UCB transplantation, many strategies to enhance engraftment and immune reconstitution are currently under investigation. This review summarizes our current understanding of engraftment and immune recovery following UCB transplantation and why this differs from allogeneic transplants using other sources of HSC. It also provides a comprehensive overview of promising techniques being used to improve myeloid and lymphoid recovery, including expansion, homing, and delivery of UCB HSC; combined use of UCB with third-party donors; isolation and expansion of natural killer cells, pathogen-specific T cells, and regulatory T cells; methods to protect and/or improve thymopoiesis. As many of these strategies are now in clinical trials, it is anticipated that UCB transplantation will continue to advance, further expanding our understanding of UCB biology and HSC transplantation.

Large granular lymphocytosis during dasatinib therapy

Dasatinib is a second generation tyrosine kinase inhibitor (TKI) approved for clinical use in patients with imatinib-resistant chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL). Large granular lymphocytes (LGLs) are medium to large cells with eccentric nuclei and abundant cytoplasm with coarse azurophilic granules. LGL lymphocytosis is caused by a proliferation of cytotoxic (CD8+) T cells and/or NK cells. In a proportion of CML and Ph(+) ALL patients, there is a significant expansion of LGLs during dasatinib therapy. LGL lymphocytosis is seen in some cases with fevers, colitis, and pleural effusions (PE), suggesting an aberrant immune response mediated by these LGLs. LGLs may participate in the elimination of the residual leukemic cells, and LGL clonal expansion is associated with excellent, long-lasting therapy responses in dasatinib-treated patients. For a more comprehensive analysis, we analyzed the morphologic, phenotypic, clinical, and functional features of the LGL subsets amplified in vivo during dasatinib therapy.

Cellular therapy of cancer with natural killer cells-where do we stand?

Although T-lymphocytes have received most of the attention in immunotherapy trials, new discoveries around natural killer (NK) cells suggest that they also should be suitable effector cells for cellular therapy of cancer. In addition to direct cytotoxicity, NK cells produce an array of immune-active cytokines, among them interferons and granulocyte-macrophage colony-stimulating factor, which places them at the crossroads of innate and adaptive immunity. They also augment monoclonal antibody activity through antibody-mediated cellular cytotoxicity and can be transfected with chimeric antigen receptors. One of the stumbling blocks for NK cell-based therapies has been the inability to predictably obtain and expand larger numbers from donors, but also to achieve sufficiently high transfection efficiency of target genes. The first clinical trials with NK cells suggest some benefit, but more definite evidence is needed to justify this relatively expensive treatment.