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

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.

Expression dynamics of the immune mediators ARG1, TBET, CIITA, IL10 and TGFB1 in chronic myeloid leukaemia patients during the first year of imatinib therapy

The use of tyrosine kinase inhibitors seems to restore the broadly compromised immune system described in chronic myeloid leukaemia (CML) patients at diagnosis leading to a re-activation of the effector-mediated immune surveillance. Here, we describe the expression dynamics of immune factors during the first year on imatinib therapy. Gene expression was evaluated in 132 peripheral blood samples from 79 CML patients, including 34 who were serially followed. An aliquot of the stored sample used to monitor BCR-ABL1 levels was retro-transcribed to cDNA and gene expression was quantified by real-time PCR. An elevated expression of ARG1 was observed at diagnosis, while TBET, CIITA, IL10 and TGFB1 were significantly decreased. Once on therapy, each gene displayed a particular behaviour. ARG1 normalized to control levels at 3 months only in optimal molecular responders and was identified as the major contributor to the difference among patients. TBET reached normal levels after 12 months in optimal responders and non-responders, regardless the Th1-response previously associated, and CIITA continued downregulated. IL10 and TGFB1 achieved normal levels early at 3 months in both groups, afterwards IL10 was sustained while TGFB1 was slightly increased after 1 year in responders. Our findings are in agreement with an immune re-activation after imatinib initiation; however, some immune mediators may require a longer exposition. The follow-up of novel and reliable biomarkers, such as ARG1, one of the principal mechanisms of myeloid-derived-suppressor cells to inhibit immune system, may be useful to deepen the characterization of early responder patients.

NK Cells in Myeloproliferative Neoplasms (MPN)

Simple Summary

NK cells are important innate immune effectors that contribute substantially to tumor control, however the role of NK cells in haematological cancers is not as well understood. The aim of this review is to highlight the importance of the role of NK cells in the management of Ph+ Myeloproliferative Neoplasms, and emphasize the need and possible benefits of a more in-depth investigation into their role in classical MPNs and show potential strategies to harness the anti-tumoral capacities of NK cells.

Abstract

Myeloproliferative neoplasms (MPNs) comprise a heterogenous group of hematologic neoplasms which are divided into Philadelphia positive (Ph+), and Philadelphia negative (Ph−) or classical MPNs. A variety of immunological factors including inflammatory, as well as immunomodulatory processes, closely interact with the disease phenotypes in MPNs. NK cells are important innate immune effectors and substantially contribute to tumor control. Changes to the absolute and proportionate numbers of NK cell, as well as phenotypical and functional alterations are seen in MPNs. In addition to the disease itself, a variety of therapeutic options in MPNs may modify NK cell characteristics. Reports of suppressive effects of MPN treatment strategies on NK cell activity have led to intensive investigations into the respective compounds, to elucidate the possible negative effects of MPN therapy on control of the leukemic clones. We hereby review the available literature on NK cells in Ph+ and Ph− MPNs and summarize today’s knowledge on disease-related alterations in this cell compartment with particular focus on known therapy-associated changes. Furthermore, we critically evaluate conflicting data with possible implications for future projects. We also aim to highlight the relevance of full NK cell functionality for disease control in MPNs and the importance of considering specific changes related to therapy in order to avoid suppressive effects on immune surveillance.

Unleashing the power of NK cells in anticancer immunotherapy

Due to their physiological role in removing damaged cells, natural killer (NK) cells represent ideal candidates for cellular immunotherapy in the treatment of cancer. Thereby, the cytotoxicity of NK cells is regulated by signals on both, the NK cells as well as the targeted tumor cells, and the interplay and balance of these signals determine the killing capacity of NK cells. One promising avenue in cancer treatment is therefore the combination of NK cell therapy with agents that either help to increase the killing capacity of NK cells or sensitize tumor cells to an NK cell-mediated attack. In this mini-review, we present different strategies that can be explored to unleash the potential of NK cell immunotherapy. In particular, we summarize how modulation of apoptosis signaling within tumor cells can be exploited to sensitize tumor cells to NK cell-mediated cytotoxicity.

Concomitant use of a dual Src/ABL kinase inhibitor eliminates the in vitro efficacy of blinatumomab against Ph+ ALL

Blinatumomab is currently approved for use as a single agent in relapsed and refractory acute lymphoblastic leukemia (ALL). Cytotoxicity is mediated via signaling through the T-cell receptor (TCR). There is now much interest in combining blinatumomab with targeted therapies, particularly in Philadelphia chromosome-positive ALL (Ph+ ALL). However, some second- and third-generation ABL inhibitors also potently inhibit Src family kinases that are important in TCR signaling. We combined ABL inhibitors and dual Src/ABL inhibitors with blinatumomab in vitro from both healthy donor samples and primary samples from patients with Ph+ ALL. Blinatumomab alone led to both T-cell proliferation and elimination of target CD19+ cells and enhanced production of interferon-γ (IFN-γ). The addition of the ABL inhibitors imatinib or nilotinib to blinatumomab did not inhibit T-cell proliferation or IFN-γ production. However, the addition of dasatinib or ponatinib inhibited T-cell proliferation and IFN-γ production. Importantly, there was no loss of CD19+ cells treated with blinatumomab plus dasatinib or ponatinib in healthy samples or samples with a resistant ABL T315I mutation by dasatinib in combination with blinatumomab. These in vitro findings bring pause to the excitement of combination therapies, highlighting the importance of maintaining T-cell function with targeted therapies.

Prospects for achieving treatment-free remission in chronic myeloid leukaemia

In addition to the best possible overall survival, discontinuation of the tyrosine kinase-inhibitor (TKI) treatment [treatment free remission (TFR)] without observing a recurrence of the disease has become a major goal of the therapy of chronic myelogenous leukemia (CML). Many clinical studies have demonstrated that TFR is possible, although for the moment limited to a fraction of the CML patients able to achieve a stable deep molecular response (DMR). The factors associated to the possibility of remaining in TFR or of losing it, have been investigated by a number of controlled and observation clinical trials and although total TKI treatment duration, DMR duration and stability and, more recently, also the depth of the molecular response obtained at the time of discontinuation have been shown to be significant elements, most of the factors associated with a higher possibility of a successful discontinuation still remain elusive and are here reviewed.

Silent NK/T cell reactions to dasatinib during sustained deep molecular response before cessation are associated with longer treatment-free remission

This study presents the final report of the multicenter, prospective tyrosine kinase inhibitor discontinuation study, D-STOP, after a 3-year follow-up of 54 patients with chronic CML who discontinued dasatinib after a sustained deep molecular response (DMR) for ≥2 years with dasatinib treatment. Estimated treatment-free remission (TFR) rates at 12 and 36 months were 63.0% [95% confidence interval (CI): 48.7-74.3] and 59.3% (95% CI: 45.0-71.0), respectively. CD3^- CD56⁺ NK, CD16⁺ CD56⁺ NK, and CD57⁺ CD56⁺ NK large granular lymphocyte (NK-LGL), CD8⁺ CD4^- cytotoxic T cell, and CD57⁺ CD3⁺ T-LGL cell numbers were relatively elevated throughout the 24-month consolidation only in failed patients who molecularly relapsed within 12 months. In successful patients, these subsets elevated transiently after 12 months, but returned to basal levels after 24-month consolidation. Therefore, smaller changes in NK/T, particularly the NK subset throughout consolidation, reflected higher TFR rates. TFR rates of those patients exhibiting elevation in CD3^- CD56⁺ NK >376 cells/μL, CD16⁺ CD56⁺ NK > 241 cells/μL, or CD57⁺ CD56⁺ NK-LGL >242 cells/μL during consolidation compared with others were 26.7% (8.3%-49.6%) vs 78.3% (55.4%-90.3%), HR 0.032 (0.0027-0.38; P = .0064), 31.2% (11.4%-53.6%) vs 85.0% (60.4%-94.9%), HR 0.039 (0.0031-0.48; P = .011), or 36.8% (16.5%-57.5%) vs 77.3% (53.7%-89.8%), HR 0.21 (0.065-0.69; P = .010), respectively. Therefore, silent responses of T/NK subsets to dasatinib throughout consolidation were significant for longer TFR. Elevated NK/T, particularly NK lymphocytes responsive to dasatinib, may be immunologically insufficient to maintain TFR. Their decline, subsequently replaced by altered lymphocyte population with less response to dasatinib during sustained DMR, might be immunologically significant. (D-STOP, NCT01627132).

γδ T Cells Number, CD200, and Flt3 Expression Is Associated with Higher Progression Free Survival in Patients with Chronic Myeloid Leukemia

BACKGROUND

Tumor immunoedition involves alterations in cells of immune system, which may play an important role in the immunosurveillance of patients with cancer diseases.

AIM OF THE STUDY

To determine the association between the number of immune cells and the expression of surface markers in leukemic cells of patients with de novo CML who achieved molecular response.

METHODS

A longitudinal study was conducted in 31 patients with de novo CML. Peripheral blood samples were obtained at diagnosis for quantification of immune cells and tumor cells expressing CD200, CD135, GpP, and Bcl-2. Results were compared with a group of 60 healthy donors. Lymphocyte subsets were analyzed during a 48 month follow-up period and molecular response to treatment was assessed simultaneously by QT-PCR. The group of patients with deep molecular response was compared with de novo CML patients; the cut-off value of cell count was determined by ROC analysis. Kaplan-Meier and Cox proportional hazard model were used to determine the significant association between the number of cells and progression-free survival.

RESULTS

Differences in number of CD4, CD4Tregs, NK, γδT, monocytes, and pDC's, tumor-cells expressing CD200⁺, CD135⁺, GpP⁺, and Bcl-2⁺ were observed between patients and healthy donors. The number of γδT lymphocytes, CD200⁺, and CD135⁺ cells were associated with longer progression-free survival (p = 0.0112, p = 0.0012 and p = 0.0201 respectively).

CONCLUSION

A γδT lymphocyte count <63 cel/uL, CD200⁺ <997 cel/uL, and CD135⁺ <23 317 cel/uL at diagnosis is associated with the maintenance of deep molecular response at 48 months in patients with de novo CML.

Skin lesions in chronic myeloid leukemia patients during dasatinib treatment

Purpose

In our work we sought to define the prevalence rates of cutaneous events during dasatinib therapy in chronic myeloid leukemia (CML) patients and to investigate the clinical and pathological characteristics of these reactions.

Patients and methods

In our institution, 67 CML patients were treated with dasatinib. it was given as first line treatment in 26 (39%) and subsequent treatment in 41 (61%) CML patients. Flow cytometry analysis of peripheral blood and cutaneous biopsy was done on all CML patients with dermatological lesions appearing during dasatinib treatment.

Results

Among 67 CML patients, 4 (5.9%) showed skin lesions during dasatinib treatment. The cutaneous manifestations were not generalized but mainly located on the back, abdomen, thorax or leg regions. The patients did not show peripheral lymphocytosis at the time when skin lesions appeared. Overall, histological analysis showed that the skin lesions were characterized by a mild perivascular small CD8+ T lymphocytes infiltrate with minimal epidermotropism.

Conclusion

The unusual T cytotoxic cutaneous infiltrate demonstrated in our CML cases could be the expression of a dasatinib-promoted lymphocyte expansion. However, the heterogeneity of the dermatologic manifestations reported in our CML patients could also be related to unknown factors specific to each CML patient. Our work highlights the finding that skin lesions may be associated with dasatinib treatment and that they should not be confused with viral or bacterial infections but rather interpreted as the clinical expression of lymphocytosis promoted by this TKI.

Dasatinib as an investigational drug for the treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia in adults

INTRODUCTION

Acute lymphoblastic leukemia (ALL) with BCR-ABL1 translocation is an aggressive malignancy that is usually treated with intensive chemotherapy with the possibility of allogeneic stem cell transplantation. The encoded fusion protein may be important for leukemogenesis; clinical studies show that dasatinib has an antileukemic effect in combination with steroids alone or intensive chemotherapy. Areas covered: Relevant publications were identified through literature searches (the used terms being acute lymphoblastic leukemia plus dasatinib) in the PubMed database. We searched for original articles and reviews describing the pharmacology and clinical use of dasatinib in ALL with BCR-ABL1. The mechanism of action, pharmacology and clinical study findings are examined. Expert opinion: Dasatinib is associated with a high complete remission rate in ALL when used alone and in combination with steroids or intensive chemotherapy. However, mutations at T315 and F317 are associated with dasatinib resistance. Overall toxicity has been acceptable in these studies and no unexpected toxicity was observed. It is not known whether the antileukemic effect of dasatinib differs between subsets of BCR-ABL1⁺ patients or is attributed to inhibition of the fusion protein alone, or a combined effect on several kinases, and whether dasatinib-containing combination treatment should be preferred in these patients instead of other emerging strategies, e.g. monoclonal antibodies.

NKG2A Down-Regulation by Dasatinib Enhances Natural Killer Cytotoxicity and Accelerates Effective Treatment Responses in Patients With Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is a hematological malignancy characterized by the presence of t(9;22) chromosomal translocation that results in BCR-ABL fusion gene. ABL tyrosine kinase inhibitors (TKIs), such as imatinib, nilotinib, and dasatinib, are currently the front-line treatment options for CML. Recently, natural killer (NK) cell activation and expansion have been shown to be associated with optimal treatment responses for CML. To investigate the effects and mechanisms of these TKIs on NK cells, here we characterized activating and inhibitory NK receptors in CD3^-CD16⁺CD56^dim NK cells isolated from CML patients in chronic phase (CP). The expressions of activating NK receptors, such as NKG2D, natural cytotoxicity receptor (NCR) and DNAM-1, rebounded after successful TKI treatments for CML. In contrast, among the three surveyed inhibitory receptors (NKG2A, KIR2DL1, and KIR3DL1), only the expression of NKG2A was reverted and suppressed to a very low level by dasatinib, and not by imatinib or nilotinib. CML patients treated with dasatinib indeed expressed fewer NKG2A+ NK cells, which send negative signals for induction of NK cytotoxicity. For these dasatinib-treated patients, the duration to reach major molecular response (MMR) was shorter, and significantly correlated with individual's NKG2A+ NK cell number. This clinical relevance to NKG2A was not observed in treatments with imatinib or nilotinib. In line with dasatinib-specific down-regulation of NKG2A, NK cytotoxicity evaluated by the killing assay was also significantly higher in patients treated with dasatinib than in those treated with imatinib or nilotinib. The lower NK cytotoxicity from imatinib or nilotinib treatments could be reverted by NKG2A blockade using anti-NKG2A antibody. Further in vitro experiments revealed mechanistically that dasatinib could inactivate p38 mitogen-activated protein kinase (MAPK), and consequently affect nuclear import of GATA-3 and GATA-3 transcriptional activities for NKG2A. Our results highlight the dual effects of dasatinib in direct inhibition of ABL kinase and in immunomodulation through NKG2A down-regulation, contributing to accelerated molecular responses (MR) in CML.

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.

[NK cells: a major role in the antitumoral immunomodulation in CML]

Convincing clinical and experimental evidence is converging on the essential role of NK (Natural Killer) cells in the recognition and eradication of tumors. Recent studies emphasized the role of NK cells in the immune control of chronic myeloid leukemia (CML), a malignancy arising from hematopoietic stem cells, and the treatment of which has been revolutionized by the use of tyrosine kinase inhibitors (TKI). Three major findings are emerging: 1) the impairment of the numbers and function of NK cells at diagnosis, 2) the restoration of the NK cell function and numbers during remissions induced with TKI therapies and 3) the potential role of the more mature NK CD56^dim cell population in maintaining relapse-free survival after stopping TKI therapy. Immunological control of CML by NK cells which has been suspected for several decades is thus a new field of investigation for future therapies.

Synergistic anti-tumor effects of dasatinib and dendritic cell vaccine on metastatic breast cancer in a mouse model

Immunotherapy is currently considered as one of the major anti-tumor modalities, but its efficacy is limited. Dasatinib could improve the expansion and recruitment of cluster of differentiation (CD) 8⁺T cells and natural killer (NK) cells to the tumor microenvironment. The present study aimed to evaluate the synergistic anti-tumor effects of dasatinib with dendritic cell (DC) vaccine in metastatic breast cancer. Dasatinib with DC vaccine was administered to mice inoculated with 4T1 breast cancer cells. Thereafter, tumor volume was measured every other day. On day 34, lung metastasis was assessed with a stereomicroscope. Tumor proliferation and angiogenesis were determined by immunohistochemistry. Apoptosis in tumor tissues was assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling. The results showed that although there were no significant differences in tumor volumes between the untreated control, DC vaccine and dasatinib groups, the tumor volume was significantly decreased in the combined treatment group compared to the other three groups. Mice in the combined treatment group showed the longest survival time, while mice treated with either single treatment had a slightly increased survival time compared to the untreated control mice. Additionally, the number of metastatic lung nodules was significantly decreased in combined treatment group compared with the dasatinib alone, DC vaccine alone and untreated control groups. Furthermore, the combined treatment group showed significantly reduced intratumoral microvessel density compared to the other three groups. In addition, the ratios of CD8⁺ T and NK cells were significantly increased in the combined treatment group compared with the other three groups. These results suggest that dasatinib combined with the DC vaccine is a possible modality for the treatment of metastatic breast cancer.

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.

Dasatinib cessation after deep molecular response exceeding 2 years and natural killer cell transition during dasatinib consolidation

Tyrosine kinase inhibitors (TKI) improve the prognosis of patients with chronic myelogenous leukemia (CML) by inducing substantial deep molecular responses (DMR); some patients have successfully discontinued TKI therapy after maintaining DMR for ≥1 year. In this cessation study, we investigated the optimal conditions for dasatinib discontinuation in patients who maintained DMR for ≥2 years. This study included 54 patients with CML who were enrolled in a D‐STOP multicenter prospective trial, had achieved DMR, and had discontinued dasatinib after 2‐year consolidation. Peripheral lymphocyte profiles were analyzed by flow cytometry. The estimated 12‐month treatment‐free survival (TFS) was 62.9% (95% confidence interval: 48.5%‐74.2%). During dasatinib consolidation, the percentage of total lymphocytes and numbers of CD3⁻ CD56⁺ natural killer (NK) cells, CD16⁺ CD56⁺ NK cells and CD56⁺ CD57⁺ NK‐large granular lymphocytes (LGL) were significantly higher in patients with molecular relapse after discontinuation but remained unchanged in patients without molecular relapse for >7 months. At the end of consolidation, patients whose total lymphocytes comprised <41% CD3⁻ CD56⁺ NK cells, <35% CD16⁺ CD56⁺ NK cells, or <27% CD56⁺ CD57⁺ NK‐LGL cells had higher TFS relative to other patients (77% vs 18%; P < .0008; 76% vs 10%; P < .0001; 84% vs 46%; P = .0059, respectively). The increase in the number of these NK cells occurred only during dasatinib consolidation. In patients with DMR, dasatinib discontinuation after 2‐year consolidation can lead to high TFS. This outcome depends significantly on a smaller increase in NK cells during dasatinib consolidation.

Dasatinib rapidly induces deep molecular response in chronic-phase chronic myeloid leukemia patients who achieved major molecular response with detectable levels of BCR-ABL1 transcripts by imatinib therapy

Background

With the introduction of imatinib, a first-generation tyrosine kinase inhibitor (TKI) to inhibit BCR-ABL1 kinase, the outcome of chronic-phase chronic myeloid leukemia (CP-CML) has improved dramatically. However, only a small proportion of CP-CML patients subsequently achieve a deep molecular response (DMR) with imatinib. Dasatinib, a second-generation TKI, is more potent than imatinib in the inhibition of BCR-ABL1 tyrosine kinase in vitro and more effective in CP-CML patients who do not achieve an optimal response with imatinib treatment.

Methods

In the present study, we attempted to investigate whether switching the treatment from imatinib to dasatinib can induce DMR in 16 CP-CML patients treated with imatinib for at least two years who achieved a major molecular response (MMR) with detectable levels of BCR-ABL1 transcripts.

Results

The rates of achievement of DMR at 1, 3, 6 and 12 months after switching to dasatinib treatment in the 16 patients were 44% (7/16), 56% (9/16), 63% (10/16) and 75% (12/16), respectively. The cumulative rate of achieving DMR at 12 months from initiation of dasatinib therapy was 93.8% (15/16). The proportion of natural killer cells and cytotoxic T cells in peripheral lymphocytes increased after switching to dasatinib. In contrast, the proportion of regulatory T cells decreased during treatment. The safety profile of dasatinib was consistent with previous studies.

Conclusion

Switching to dasatinib would be a therapeutic option for CP-CML patients who achieved MMR but not DMR by imatinib, especially for patients who wish to discontinue TKI therapy.

Immunotherapeutic properties of chemotherapy

Impressive remissions driven by immunological checkpoint blockade in cancer patients have prompted the scientific community to investigate afresh the crosstalk between cancer cells and the patient's immune system. Preclinical and clinical studies have highlighted that the anticancer efficacy of some conventional chemotherapeutics is based on their ability to restore anticancer immune responses. The current challenge is to understand and circumvent immune resistance mechanisms to chemo- and immunotherapies to design relevant immunotherapy and chemotherapy combinations. In this review, we will summarize which immunological processes are involved in the anticancer action of some cytotoxic agents and discuss the recently unraveled contribution of the gut microbiota into the immunogenicity of anticancer drugs. We will eventually introduce the scientific rationale for therapeutic strategies combining chemotherapeutic drugs and immune checkpoint blockers.

Dasatinib versus imatinib in Japanese patients with newly diagnosed chronic phase chronic myeloid leukemia: a subanalysis of the DASISION 5-year final report

The international phase III DASISION trial demonstrated improved efficacy of dasatinib versus imatinib in treatment-naive patients with chronic myeloid leukemia in the chronic phase (CML-CP). We report efficacy and safety outcomes in a Japanese population from the final, 5-year follow-up of DASISION. At the end of the study, 77% (20/26) of dasatinib-treated and 61% (14/23) of imatinib-treated patients remained on initial therapy. Improved responses were observed in Japanese patients who received dasatinib versus imatinib (complete cytogenetic response: 96 vs 87%; major molecular response: 88 vs 74%; BCR-ABL1 ≤0.0032% International Scale [MR^4.5]: 58 vs 52%). In patients who achieved BCR-ABL1 ≤10% at 3 months, 5-year progression-free survival and overall survival rates were high with dasatinib (96 and 96%) and imatinib (88 and 100%). The majority of adverse events were grade 1/2 in Japanese patients. Pleural effusion occurred more frequently in dasatinib-treated Japanese patients versus all patients (42 vs 28%), with no treatment discontinuations. Overall, in Japanese patients, dasatinib maintained its safety profile and had higher or comparable response and survival outcomes compared with imatinib or with all patients in DASISION. These findings demonstrate the long-term efficacy and tolerability of dasatinib and support frontline treatment of Japanese patients with CML-CP with dasatinib.

CML patients with deep molecular responses to TKI have restored immune effectors and decreased PD-1 and immune suppressors

Increased immune suppressors and PD-1 abrogates effector responses in CML patients at diagnosis. Enhanced net effector immune responses and decreased PD-1 and immune suppressors may promote sustained deep molecular response in CML.

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.

Clinical Perspectives on Targeting Therapies for Personalized Medicine

Expected benefits from new technology include more efficient patient selection for clinical trials, more cost-effective treatment pathways for patients and health services and a more profitable accelerated approach for drug developers. Regulatory authorities expect the pharmaceutical and biotechnology industries to accelerate their development of companion diagnostics and companion therapeutics toward the goal of safer and more effective personalized medicine, and expect health services to fund and prescribers to adopt these new therapeutic technologies.

This review discusses the importance of a range of new approaches to developing new and reprofiled medicines to treat common and serious diseases, and rare diseases: new network pharmacology approaches, adaptive trial designs with enriched populations more likely to respond safely to treatment, as assessed by companion diagnostics for response and toxicity risk and use of “real world” data.

Case studies are described of single and multiple protein drug targets in several important therapeutic areas. These case studies also illustrate the value and complexity of use of selective biomarkers of clinical response and risk of adverse drug effects, either singly or in combination.

Immunological Effects of Conventional Chemotherapy and Targeted Anticancer Agents

The tremendous clinical success of checkpoint blockers illustrates the potential of reestablishing latent immunosurveillance for cancer therapy. Although largely neglected in the clinical practice, accumulating evidence indicates that the efficacy of conventional and targeted anticancer agents does not only involve direct cytostatic/cytotoxic effects, but also relies on the (re)activation of tumor-targeting immune responses. Chemotherapy can promote such responses by increasing the immunogenicity of malignant cells, or by inhibiting immunosuppressive circuitries that are established by developing neoplasms. These immunological "side" effects of chemotherapy are desirable, and their in-depth comprehension will facilitate the design of novel combinatorial regimens with improved clinical efficacy.