Direct effect of dasatinib on signal transduction pathways associated with a rapid mobilization of cytotoxic lymphocytes

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.

Cord Blood-Derived Natural Killer Cell Exploitation in Immunotherapy Protocols: More Than a Promise?

Simple Summary

NK cell anti-tumor activity against hematological malignancies is well-established and many studies support their role in the control of solid tumor growth and metastasis generation. However, tumor microenvironment may affect NK cell function. Ongoing studies are aimed to design novel immunotherapeutic protocols to combine NK cell-based immunotherapy with other therapeutic strategies to improve the anti-tumor NK cell response. In this context, UCB is one of the main sources of both mature NK cells and of CD34⁺ HSPC that can generate NK cells, both in-vivo and in-vitro. UCB-derived NK cells represent a valuable tool to perform in-vitro and preclinical analyses and are already used in several clinical settings, particularly against hematological malignancies. The present review describes the characteristics of different types of UCB-derived NK cells and the in-vitro models to expand them, both for research and clinical purposes in the context of cancer immunotherapy.

Abstract

In the last 20 years, Natural Killer (NK) cell-based immunotherapy has become a promising approach to target various types of cancer. Indeed, NK cells play a pivotal role in the first-line defense against tumors through major histocompatibility complex-independent immunosurveillance. Their role in the control of leukemia relapse has been clearly established and, moreover, the presence of NK cells in the tumor microenvironment (TME) generally correlates with good prognosis. However, it has also been observed that, often, NK cells poorly infiltrate the tumor tissue, and, in TME, their functions may be compromised by immunosuppressive factors that contribute to the failure of anti-cancer immune response. Currently, studies are focused on the design of effective strategies to expand NK cells and enhance their cytotoxic activity, exploiting different cell sources, such as peripheral blood (PB), umbilical cord blood (UCB) and NK cell lines. Among them, UCB represents an important source of mature NK cells and CD34⁺ Hematopoietic Stem and Progenitor Cells (HSPCs), as precursors of NK cells. In this review, we summarize the UCB-derived NK cell activity in the tumor context, review the different in-vitro models to expand NK cells from UCB, and discuss the importance of their exploitation in anti-tumor immunotherapy protocols.

Thrombopoietin Levels During Tyrosine Kinase Inhibitor Therapy for Chronic Myeloid Leukemia

BACKGROUND AND OBJECTIVE

Although it is well known that platelet depletion is one of the major adverse events related to tyrosine kinase inhibitor (TKI) therapy, the effect of TKIs on thrombopoietin (TPO), a stimulating factor for thrombopoiesis, has not been examined to date. In this study, we investigated the effect of TKIs on the levels of plasma TPO concentration in patients with well-controlled chronic myeloid leukemia receiving imatinib or dasatinib and those in treatment-free remission (TFR).

METHODS

Blood samples for blood cell counts and plasma TPO levels were obtained from 23 dasatinib-treated patients before and 1 h after intake, 11 patients treated with imatinib before and 2 h after intake, and nine TFR patients. Levels of plasma TPO were determined by using enzyme-linked immunosorbent assays.

RESULTS

Levels of TPO were significantly inversely correlated with platelet counts in the entire cohort (r = - 0.568, p < 0.0001). Dasatinib intake, but not imatinib, significantly reduced platelet counts after intake (p = 0.0009 in dasatinib and p = 0.5431 in imatinib). However, imatinib and dasatinib intake increased the levels of TPO in these patients (p = 0.0024, dasatinib; p = 0.0098, imatinib).

CONCLUSIONS

Our study results suggest that neither dasatinib nor imatinib therapy inhibits TPO production. Rather, transient increases in TPO levels seen with these two treatments might be a result of the decrease in TPO clearance these TKIs confer. However, further investigations are required to clarify the effect of TKIs on thrombopoiesis.

Effect of Tyrosin Kinase Inhibitors on NK Cell and ILC3 Development and Function

Tyrosin kinase inhibitors (TKI) sharply improved the prognosis of Chronic Myeloid Leukemia (CML) and of Philadelphia+ Acute Lymphoblastic Leukemia (Ph+ALL) patients. However, TKI are not curative because of the development of resistance and lack of complete molecular remission in the majority of patients. Clinical evidences would support the notion that patient's immune system may play a key role in preventing relapses. In particular, increased proportions of terminally differentiated CD56+CD16+CD57+ NK cells have been reported to be associated with successful Imatinib therapy discontinuation or with a deep molecular response in Dasatinib-treated patients. In view of the potential role of NK cells in immune-response against CML, it is important to study whether any TKI have an effect on the NK cell development and identify possible molecular mechanism(s) by which continuous exposure to in vitro TKI may influence NK cell development and repertoire. To this end, CD34+ hematopoietic stem cells (HSC) were cultured in the absence or in the presence of Imatinib, Nilotinib, or Dasatinib. We show that all compounds exert an inhibitory effect on CD56+ cell recovery. In addition, Dasatinib sharply skewed the repertoire of CD56+ cell population, leading to an impaired recovery of CD56+CD117-CD16+CD94/NKG2A+EOMES+ mature cytotoxic NK cells, while the recovery of CD56+CD117+CD94/NKG2A-RORγt+ IL-22-producing ILC3 was not affected. This effect appears to involve the Dasatinib-mediated inhibition of Src kinases and, indirectly, of STAT5-signaling activation in CD34+ cells during first days of culture. Our studies, reveal a possible mechanism by which Dasatinib may interfere with the proliferation and maturation of fully competent NK cells, i.e., by targeting signaling pathways required for differentiation and survival of NK cells but not of ILC3.

The tyrosine kinase inhibitor dasatinib reduces the growth of intracellular Mycobacterium tuberculosis despite impairing T-cell function

Tyrosine kinases are checkpoints for multiple cellular pathways and dysregulation induces malignancies, most notably chronic myeloid leukemia (CML). Inhibition of Abl-tyrosine kinases has evolved as a new concept for the treatment of CML and other malignant diseases. Due to the multiple immune-modulatory pathways controlled by tyrosine kinases, treatment with tyrosine kinase inhibitors (TKIs) will not only affect the biology of malignant cells but also modulate physiological immune functions. To understand the effects of TKIs on host defense against intracellular bacteria, we investigated the immunological impact of the dual Abl/Src TKI dasatinib on the cellular immune response to Mycobacterium tuberculosis (Mtb). Our results demonstrate that dasatinib impaired proliferation, cytokine release (IFN-γ, TNF-α, GM-CSF), expression of granulysin and degranulation of cytotoxic effector molecules of human Mtb-specific T-lymphocytes by inhibition of lymphocyte-specific protein tyrosine kinase (Lck) phosphorylation. Despite this profound inhibition of T-cell function, dasatinib suppressed growth of virulent Mtb in human macrophages co-cultured with autologous Mtb-specific T-cells (49±15%). Functional analysis suggested that growth inhibition is due to dasatinib-triggered lysosomal acidification in Mtb-infected macrophages. These results highlight the significance of innate immune responses, i.e. acidification of lysosomes, which control the multiplication of intracellular bacteria despite the lack of efficient T-cell support.

Methods and approaches to disease mechanisms using systems kinomics

All cellular functions, ranging from regular cell maintenance and homeostasis, specialized functions specific to cellular types, or generating responses due to external stimulus, are mediated by proteins within the cell. Regulation of these proteins allows the cell to alter its behavior under different circumstances. A major mechanism of protein regulation is utilizing protein kinases and phosphatases; enzymes that catalyze the transfer of phosphates between substrates [1]. Proteins involved in phosphate signaling are well studied and include kinases and phosphatases that catalyze opposing reactions regulating both structure and function of the cell. Kinomics is the study of kinases, phosphatases and their targets, and has been used to study the functional changes in numerous diseases and infectious diseases with aims to delineate the cellular functions affected. Identifying the phosphate signaling pathways changed by certain diseases or infections can lead to novel therapeutic targets. However, a daunting 518 putative protein kinase genes have been identified [2], indicating that this protein family is very large and complex. Identifying which enzymes are specific to a particular disease can be a laborious task. In this review, we will provide information on large-scale systems biology methodologies that allow global screening of the kinome to more efficiently identify which kinase pathways are pertinent for further study.

The Efficacy of Reduced-dose Dasatinib as a Subsequent Therapy in Patients with Chronic Myeloid Leukemia in the Chronic Phase: The LD-CML Study of the Kanto CML Study Group

Objective The aim of this study was to prospectively investigate the efficacy and safety profiles of low-dose dasatinib therapy (50 mg once daily). Methods Patients with chronic myeloid leukemia in the chronic phase (CML-CP) who were being treated with low-dose imatinib (≤200 mg/day), but were resistant to this agent were enrolled in the current study (referred to as the LD-CML study). Results There subjects included 9 patients (4 men and 5 women); all were treated with dasatinib at a dose of 50 mg once daily. Among 8 patients who had not experienced major molecular response (MMR; BCR-ABL1 transcript ≤0.1% according to International Scale [IS]) at study enrollment, 5 attained MMR by 12 months. In particular, 3 of 9 patients demonstrated a deep molecular response (DMR; IS ≤0.0069%) by 18 months. Five patients developed lymphocytosis accompanied by cytotoxic lymphocyte predominance. There was no mortality or disease progression, and all continue to receive dasatinib therapy at 18 months with only 2 patients requiring dose reduction. Toxicities were mild-to-moderate, and pleural effusion was observed in 1 patient (grade 1). Conclusion Low-dose dasatinib can attain MMR and DMR without severe toxicity in patients with CML-CP who are unable to achieve MMR with low-dose imatinib. Switching to low-dose dasatinib should therefore be considered for patients in this setting, especially if they are otherwise considering a cessation of treatment.

PLOD2 regulated by transcription factor FOXA1 promotes metastasis in NSCLC

In multiple types of tumors, fibrotic collagen is regarded as the 'highway' for cancer cell migration, which is mainly modified by lysyl hydroxylase 2 (PLOD2). The previous findings have demonstrated that the expression of PLOD2 was regulated by multiple factors, including HIF-1α, TGF-β and microRNA-26a/b. Although PLOD2 was confirmed to be related to poor prognosis in lung adenocarcinoma, the regulatory mechanism and function of PLOD2 in human lung adenocarcinoma is poorly understood. On the other hand, upregulation or hyperactivation of epidermal growth factor receptor is considered as a prognostic marker in many cancers, especially in non-small-cell lung cancer (NSCLC). In this study, we found that PLOD2 was elevated in NSCLC specimens and positively links to NSCLC poor prognosis. Gain- and loss-of-function studies and orthotopic implantation metastasis model pinpointed that PLOD2 promotes NSCLC metastasis directly by enhancing migration and indirectly by inducing collagen reorganization. In addition, we revealed that PLOD2 was regulated by PI3K/AKT-FOXA1 axis. The transcription factor FOXA1 directly bound to the PLOD2 promoter, and turned on PLOD2 transcription. In summary, our findings revealed a regulatory mechanism of NSCLC metastasis through EGFR-PI3K/AKT-FOXA1-PLOD2 pathway, and provided PLOD2 as a therapeutic target for NSCLC treatment.

Direct effect of dasatinib on signal transduction pathways associated with a rapid mobilization of cytotoxic lymphocytes

It has been shown that an increase in cytotoxic lymphocyte counts in the peripheral blood occurs rapidly after taking dasatinib, but the underlying mechanism is not yet elucidated. To investigate the influence of dasatinib on signal transduction pathways, we investigated the changes in JAK-STAT, mitogen-activated protein kinase (MAPK), and AKT in cytotoxic lymphocytes, including natural killer (NK) cells and cytotoxic T lymphocytes (CTLs), before and after dasatinib treatment in chronic myeloid leukemia patients. Among a total of 30 patients, 18 were treated with dasatinib, nine with imatinib, and three with nilotinib. At constitutive levels, the expression of phosphorylated proteins, pSTAT1, pSTAT3, and pERK in NK cells and pSTAT3 in CTLs, was significantly higher in dasatinib-treated patients. Among the patients evaluated, only dasatinib-treated patients showed inhibition of multiple signaling pathways after taking a tyrosine kinase inhibitor. The magnitude of pERK and pAKT inhibition was closely associated with an increase in NK cells and CTLs, respectively, after taking a tyrosine kinase inhibitor. Those responses were more evident in patients with cytomegalovirus IgG positivity. In this study, we demonstrated for the first time, the influence of dasatinib on cell events in cytotoxic lymphocytes in vivo and explained the possible underlying mechanism that results in lymphocyte mobilization after dasatinib treatment.