Browsing by Subject "CML"

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  • Radujkovic, Aleksandar; Dietrich, Sascha; Blok, Henric-Jan; Nagler, Arnon; Ayuk, Francis; Finke, Juergen; Tischer, Johanna; Mayer, Jiri; Koc, Yener; Sora, Federica; Passweg, Jakob; Byrne, Jenny L.; Jindra, Pavel; Veelken, Joan Hendrik; Socie, Gerard; Maertens, Johan; Schaap, Nicolaas; Stadler, Michael; Itälä-Remes, Maija; Tholouli, Eleni; Arat, Mutlu; Rocha, Vanderson; Ljungman, Per; Yakoub-Agha, Ibrahim; Kroeger, Nicolaus; Chalandon, Yves (2019)
    The prognosis of patients with blast crisis (BC) chronic myeloid leukemia (CML) is still dismal. Allogeneic stem cell transplantation represents the only curative treatment option, but data on transplant outcomes are scarce. We therefore conducted a retrospective, registry-based study of adult patients allografted for BC CML, focusing on patients with active disease at transplant and pretransplant prognostic factors. One hundred seventy patients allografted for BC CML after tyrosine kinase inhibitor pretreatment between 2004 and 2016 were analyzed. Before transplant, 95 patients were in remission, whereas 75 patients had active BC. In multivariable analysis of the entire cohort, active BC at transplant was the strongest factor associated with decreased overall survival (hazrd ratio, 1.87; P = .010) and shorter leukemia-free survival (LFS; hazard ratio, 1.69; P= .017). For patients with BC in remission at transplant, advanced age (>= 45 years), lower performance status (12 months), myeloablative conditioning, and unrelated donor (UD) transplant were risk factors for inferior survival. In patients with active BC, only UD transplant was significantly associated with prolonged LFS and trended toward improved overall survival. In summary, survival of patients allografted for BC CML was strongly dependent on pretransplant remission status. In patients with remission of BC, conventional prognostic factors remained the major determinants of outcome, whereas in those with active BC at transplant, UD transplant was associated with prolonged LFS in our study. (C) 2019 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.
  • Bui, Thi Phuong Nam; Troise, Antonio Dario; Fogliano, Vincenzo; de Vos, Willem M. (2019)
    Modifications of lysine contribute to the amount of dietary advanced glycation end-products reaching the colon. However, little is known about the ability of intestinal bacteria to metabolize dietary N-epsilon-carboxymethyllysine (CML). Successive transfers of fecal microbiota in growth media containing CML were used to identify and isolate species able to metabolize CML under anaerobic conditions. From our study, only donors exposed to processed foods degraded CML, and anaerobic bacteria enrichments from two of them used 77 and 100% of CML. Oscillibacter and Cloacibacillus evryensis increased in the two donors after the second transfer, highlighting that the bacteria from these taxa could be candidates for anaerobic CML degradation. A tentative identification of CML metabolites produced by a pure culture of Cloacibacillus evryensis was performed by mass spectrometry: carboxymethylated biogenic amines and carboxylic acids were identified as CML degradation products. The study confirmed the ability of intestinal bacteria to metabolize CML under anoxic conditions.
  • El Missiry, Mohamed; Awad, Shady Adnan; Koskela, Hanna Laura Maria; Al-Samadi, Ahmed; Ekblom, Marja; Markevan, Berit; Astrand-Grundstrom, Ingbritt; Wold, Maren; Svedahl, Ellen Rabben; Juhl, Birgitte Ravn; Bjerrum, Ole Weis; Haulin, Inger; Porkka, Kimmo; Olsson-Stromberg, Ulla; Hjorth-Hansen, Henrik; Mustjoki, Satu (2016)
    Tyrosine kinase inhibitors (TKIs) used in the treatment of chronic myeloid leukaemia have been reported to induce immunomodulatory effects. We aimed to assess peripheral blood (PB) and bone marrow (BM) lymphocyte status at the diagnosis and during different TKI therapies and correlate it with treatment responses. BM and PB samples were acquired from 105 first-line TKI-treated patients. Relative number of BM lymphocytes was evaluated from MGG-stained BM aspirates, and immunophenotypic analyses were performed with multicolour flow cytometry. Early 3-month expansion of BM lymphocytes was found during all different TKIs (imatinib n = 71, 20 %; dasatinib n = 25, 21 %; nilotinib n = 9, 22 %; healthy controls n = 14, 12 %, p <0.0001). Increased PB lymphocyte count was only observed during dasatinib therapy. The BM lymphocyte expansion was associated with early molecular response; patients with 3-month BCR-ABL1 <10 % showed higher lymphocyte counts than patients with BCR-ABL1 > 10 % (23 vs. 17 %, p <0.05). Detailed phenotypic analysis showed that BM lymphocyte expansion consisted of various lymphocyte subclasses, but especially the proportion of CD19+ B cells and CD3negCD16/56+ NK cells increased from diagnostic values. During dasatinib treatment, the lymphocyte balance in both BM and PB was shifted more to cytotoxic direction (increased CD8+CD57+ and CD8+HLA-DR+ cells, and low T regulatory cells), whereas no major immunophenotypic differences were observed between imatinib and nilotinib patients. Early BM lymphocytosis occurs with all current first-line TKIs and is associated with better treatment responses. PB and BM immunoprofile during dasatinib treatment markedly differs from both imatinib- and nilotinib-treated patients.
  • Landberg, Niklas; von Palffy, Sofia; Askmyr, Maria; Lilljebjorn, Henrik; Sanden, Carl; Rissler, Marianne; Mustjoki, Satu; Hjorth-Hansen, Henrik; Richter, Johan; Agerstam, Helena; Jaras, Marcus; Fioretos, Thoas (2018)
    Tyrosine kinase inhibitors (TKIs) are highly effective for the treatment of chronic myeloid leukemia (CML), but very few patients are cured. The major drawbacks regarding TKIs are their low efficacy in eradicating the leukemic stem cells responsible for disease maintenance and relapse upon drug cessation. Herein, we performed ribonucleic acid sequencing of flow-sorted primitive (CD34(+) CD38(low)) and progenitor (CD34(+) CD38(+)) chronic phase CML cells, and identified transcriptional upregulation of 32 cell surface molecules relative to corresponding normal bone marrow cells. Focusing on novel markers with increased expression on primitive CML cells, we confirmed upregulation of the scavenger receptor CD36 and the leptin receptor by flow cytometry. We also delineate a subpopulation of primitive CML cells expressing CD36 that is less sensitive to imatinib treatment. Using CD36 targeting anti-bodies, we show that the CD36 positive cells can be targeted and killed by antibody-dependent cellular cytotoxicity. In summary, CD36 defines a subpopulation of primitive CML cells with decreased imatinib sensitivity that can be effectively targeted and killed using an anti-CD36 anti-body.
  • El Missiry, Mohamed; Hjorth-Hansen, Henrik; Richter, Johan; Olson-Stromberg, Ulla; Stenke, Leif; Porkka, Kimmo; Kreutzman, Anna; Mustjoki, Satu (2017)
    In chronic myeloid leukemia (CML), early treatment prediction is important to identify patients with inferior overall outcomes. We examined the feasibility of using reductions in BCR-ABL1 transcript levels after 1 month of tyrosine kinase inhibitor (TKI) treatment to predict therapy response. Fifty-two first-line TKI-treated CML patients were included (imatinib n = 26, dasatinib n = 21, nilotinib n = 5), and BCR-ABL1 transcript levels were measured at diagnosis (dg) and 1, 3, 6, 12, 18, 24, and 36 months. The fold change of the BCR-ABL1 transcripts at 1 month compared to initial BCR-ABL1 transcript levels was used to indicate early therapy response. In our cohort, 21% of patients had no decrease in BCR-ABL1 transcript levels after 1 month and were classified as poor responders. Surprisingly, these patients had lower BCR-ABL1 transcript levels at dg compared to responders (31% vs. 48%, p = 0.0083). Poor responders also significantly more often had enlarged spleen (55% vs. 15%; p<0.01) and a higher percentage of Ph+ CD34+CD38- cells in the bone marrow (91% vs. 75%, p<0.05). The major molecular response rates were inferior in the poor responders (at 12m 18% vs. 64%, p<0.01; 18m 27% vs. 75%, p<0.01; 24m 55% vs. 87%, p<0.01). In conclusion, early treatment response analysis defines a biologically distinct patient subgroup with inferior long-term outcomes.
  • Ylinen, Varpu (Helsingfors universitet, 2016)
    Chronic myeloid leukemia (CML) is a malignant hematologic disorder, which is fatal without a treatment. Oral tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of CML and transformed the disease to a chronic condition that can be treated at patient's home. The common problem in the treatment of CML is patient's poor adherence to TKIs. The regular, consistent use of TKIs is crucial to keep disease under control. For this reason and to obtain an optimal treatment outcome, adherence to TKIs is extremely important. The aim of the study was to assess reasons for poor adherence to TKI-medications in Finnish CMLpatients, including patient characteristics, treatment related factors, comorbidities and concomitant medications. In addition, patients' experiences, beliefs, knowledge and perception about CML and its treatment were explored and how these could contribute to nonadherent behaviour. This study is part of the larger study, assessing adherence to TKI treatment among Finnish CML population. The data was obtained by using patient questionnaires and semi-structured theme-interview during patient meetings in 2012. Study population consisted of Finnish adult CML patients who had been on TKI -medication (imatinib, nilotinib or dasatinib) for more than six months prior to the study baseline. Patients' adherence was measured using Morisky Medication Adherence 8-Item Scale (MMAS-8) and based on their score, patients were divided into three groups: high, medium and low adherence. Both quantitative and qualitative methods were used in data analysis. Study findings show that 21% (n=18) of the patients were low adherent and 23% (n=20) were high adherent to their treatment. Patient sociodemographic characteristics or experienced adverse drug reactions (ADRs) did not predict adherence, while more concomitant medications and comorbidities were associated with high adherence. However, ADRs had negative effect on the quality of life of several nonadherent patients. All nonadherent patients reported unintentional nonadherence and the most common reason was forgetting. Two-thirds of the patients (n=12) reported intentional nonadherence, which often was a result of experienced ADRs. The knowledge of CML and its treatment was poor among all patients while over half of the nonadherent patients (n=11) thought that they received enough information received. Overall, patients were very satisfied with care provided by the hospitals, physicians and other healthcare professionals. Managing TKI-treatment regimen is challenging for many patients and ADRs can have a negative impact on the quality of life. Healthcare professionals should regularly assess patient adherence and provide information and support for the patients to help them to succeed in medication management. Reasons for poor adherence are complex and have to be identified from each individual patient so that adherence can be improved.
  • Kreutzman, Anna; Yadav, Bhagwan; Brummendorf, Tim H.; Gjertsen, Bjorn Tore; Lee, Moon Hee; Janssen, Jeroen; Kasanen, Tiina; Koskenvesa, Perttu; Lotfi, Kourosh; Markevärn, Berit; Olsson-Stromberg, Ulla; Stentoft, Jesper; Stenke, Leif; Söderlund, Stina; Udby, Lene; Richter, Johan; Hjörth-Hansen, Henrik; Mustjoki, Satu (2019)
    Changes in the immune system induced by tyrosine kinase inhibitors (TKI) have been shown to positively correlate with therapy responses in chronic myeloid leukemia (CML). However, only a few longitudinal studies exist and no randomized comparisons between two TKIs have been reported. Therefore, we prospectively analyzed the immune system of newly diagnosed CML patients treated with imatinib (n = 20) or bosutinib (n = 13), that participated in the randomized BFORE trial (NCT02130557). Comprehensive immunophenotyping, plasma protein profiling, and functional assays to determine activation levels of T and NK cells were performed at diagnosis, 3, and 12 months after therapy start. All results were correlated with clinical parameters such as Sokal risk and BCR-ABL load measured according to IS%. At diagnosis, low Sokal risk CML patients had a higher frequency of cytotoxic cells (CD8 + T and NK cells), increased cytotoxic potential of NK cells and lower frequency of naive and central memory CD4 + T cells. Further, soluble plasma protein profile divided patients into two distinct clusters with different disease burden at diagnosis. During treatment, BCR-ABL IS% correlated with immunological parameters such as plasma proteins, together with different memory subsets of CD4+ and CD8 + T cells. Interestingly, the proportion and cytotoxic potential of NK cells together with several soluble proteins increased during imatinib treatment. In contrast, no major immunological changes were observed during bosutinib treatment. In conclusion, imatinib and bosutinib were shown to have differential effects on the immune system in this randomized clinical trial. Increased number and function of NK cells were especially observed during imatinib therapy.
  • Rebane, Anni (Helsingin yliopisto, 2015)
    Given the success of first-line treatment in chronic myeloid leukemia (CML), the prevalence of the disease is estimated to increase and more patients are expected to develop resistance to therapy. Thus, even relatively rare point mutations are likely to become more common. In CML, the uncontrollable division of myeloid cells is caused by a reciprocal translocation of chromosomes 9 and 22, resulting in the Philadelphia chromosome. At the meeting point of the two chromosomes, breakpoint cluster region (BCR) and Abelson proto-oncogene 1 (ABL1) fuse together to form the chimeric fusion oncogene BCR-ABL1, the latter of which, the non-receptor tyrosine kinase ABL1, is the driver of the disease. Since the tyrosine kinase inhibitor (TKI) imatinib became available in 2001, the success of first-line therapy has significantly improved the prognosis of CML patients. However, up to 50% of patients with imatinib-refractory disease develop resistance due to point mutations in ABL1, and the most common mutation to emerge is BCR-ABL1 T315I. The broad-range TKI ponatinib is the only approved TKI that inhibits the kinase activity of BCR-ABL1 T315I, but adverse side effects leave patients with this mutation in need of a better, safer, and more effective treatment. The kinase inhibitor axitinib was shown to be selective for BCR-ABL1 T315I, but mutations that emerge as a consequence of axitinib-resistance have yet to be explored. Moreover, patients with the T315I mutation treated with ponatinib have been reported to develop highly drug-resistant mutations in BCR-ABL1 such as T315M and the E255V/T315I compound mutation. The purpose of this study was to identify mutations that enable cells to develop resistance to the kinase inhibitor axitinib and to find new, potential inhibitors for cells expressing the drug-resistant mutations BCR-ABL1 T315I, BCR-ABL1 T315M, and BCR-ABL1 E255V/T315I. To this end, mouse hematopoietic cell lines were constructed prior to determining cell viability in response to inhibitors in combinations and as independent agents. As a novel finding, cells stably expressing T315M were found to exhibit sensitivity to inhibitors of topoisomerase II and mTOR. Moreover, synthetic lethality occurred in these cells in response to the combined treatment of the allosteric inhibitor asciminib and the TKI ponatinib, although not in clinically relevant doses. The highly resistant cells expressing BCR-ABL1 E255V/T315I, like cells expressing T315I and T315M, showed sensitivity to conventional chemotherapy. Notably, however, three SMAC mimetics displayed selectivity to cells expressing BCR-ABL1 E255V/T315I over cells expressing only the single T315I mutation. Considering that CML is expected to become increasingly prevalent, more patients are estimated to develop resistance to therapy. As even relatively rare mutations in BCR-ABL1 become more common, finding an effective treatment for cells expressing these highly resistant mutations takes us one step closer to identifying a safe and effective treatment for CML patients carrying those mutations.
  • Gratwohl, Alois; Iacobelli, Simona; Bootsman, Natalia; van Biezen, Anja; Baldomero, Helen; Arcese, William; Arnold, Renate; Bron, Dominique; Cordonnier, Catherine; Ernst, Peter; Ferrant, Augustin; Frassoni, Francesco; Gahrton, Gosta; Richard, Carlos; Kolb, Hans Jochem; Link, Hartmut; Niederwieser, Dietger; Ruutu, Tapani; Schattenberg, Anton; Schmitz, Norbert; Torres-Gomez, Antonio; Zwaan, Ferry; Apperley, Jane; Olavarria, Eduardo; Kroeger, Nicolaus; European Soc Blood Marrow Transpla (2016)
    In the context of discussions on the reproducibility of clinical studies, we reanalyzed a prospective randomized study on the role of splenic irradiation as adjunct to the conditioning for hematopoietic stem cell transplantation (HSCT) for chronic myeloid leukemia (CML). Between 1986 and 1989, a total of 229 patients with CML were randomized; of these, 225 (98 %; 112 with, 113 without splenic irradiation) could be identified in the database and their survival updated. Results confirmed the early findings with no significant differences in all measured endpoints (overall survival at 25 years: 42.7 %, 32.0-52.4 % vs 52.9 %, 43.2-62.6 %; p = 0.355, log rank test). Additional splenic irradiation failed to reduce relapse incidence. It did not increase non-relapse mortality nor the risk of late secondary malignancies. Comforting are the long-term results from this predefined consecutive cohort of patients: more than 60 % were alive at plus 25 years when they were transplanted with a low European Society for Blood and Marrow Transplantation (EBMT) risk sore. This needs to be considered today when treatment options are discussed for patients who failed initial tyrosine kinase inhibitor therapy and have an available low risk HLA-identical donor.
  • Vakkila, Emmi (Helsingfors universitet, 2016)
    Tutkielman aiheena oli kroonista myeloista leukemiaa sairastavien potilaiden T-solujen aktiivisuus ja sytokiinituotanto. Potilasmateriaalina oli ns. STOP-tutkimuksen potilaat, joita on seurattu Hematologisessa tutkimusyksikössä vuodesta 2006. STOP- tutkimuksen yhtenä kiinnostuskohteena oli KML-potilaiden mahdollinen paraneminen ja molekylaarisen vasteen säilyminen tyrosiinikinaasi-inhibiittorilääkityksen loputtua. Tässä projektissa vertasin relapsoituneiden potilaiden valkosoluja remission säilyttäneiden potilaiden valkosoluihin. T-solujen aktivaation jälkeen tulokset analysoitiin virtaussytometrialla. Tulosten perusteella vaikuttaa siltä, että remission säilyttäneillä potilailla sytokiinituotanto (IFN-γ ja TNF-α) on voimakkaampaa kuin relapsoituneilla potilailla. Tämä voi osin selittää, miksi remission säilyttäminen on joillain potilailla onnistunut pitkäaikaisesti. Tulokset tulee kuitenkin vahvistaa meneillään olevissa kliinisissä tutkimuksissa, joissa on suurempi potilasmäärä mukana.
  • Bouillon, Anne-Sophie; Ferreira, Monica S. Ventura; Awad, Shady Adnan; Richter, Johan; Hochhaus, Andreas; Kunzmann, Volker; Dengler, Jolanta; Janssen, Jeroen; Ossenkoppele, Gert; Westerweel, Peter E.; Boekhorst, Peter A. W. te; Mahon, Francois-Xavier; Hjorth-Hansen, Henrik; Isfort, Susanne; Fioretos, Thoas; Hummel, Sebastian; Schemionek, Mirle; Wilop, Stefan; Koschmieder, Steffen; Saussele, Susanne; Mustjoki, Satu; Beier, Fabian; Brümmendorf, Tim H. (2018)
    Telomere length (TL) in peripheral blood (PB) cellsofpatientswith chronic myeloid leukemia(CML) has been shown to correlate with disease stage, prognostic scores, response to therapy, and disease progression. However, due to considerable genetic interindividual variability, TL varies substantially between individuals, limiting its use as a robust prognostic marker in individual patients. Here, we compared TL of BCR-ABL(-), nonleukemic CD34(+)CD38(-) hematopoietic stem cells (HSC) in the bone marrow of CML patients at diagnosis to their individual BCR-ABL(+) leukemic stem cell (LSC) counterparts. We observed significantly accelerated telomere shortening in LSC compared with nonleukemic HSC. Interestingly, the degree of LSC telomere shortening was found to correlate significantly with the leukemic clone size. To validate the diagnostic value of nonleukemic cells as internal controls and to rule out effects of tyrosine kinase inhibitor (TKI) treatment on these nontarget cells, we prospectively assessed TL in 134 PB samples collected in deep molecular remission after TKI treatment within the EURO-SKI study (NCT01596114). Here, no significant telomere shortening was observed in granulocytes compared with an age-adjusted control cohort. In conclusion, this study provides proof of principle for accelerated telomere shortening in LSC as opposed to HSC in CML patients at diagnosis. The fact that the degree of telomere shortening correlates with leukemic clone's size supports the use of TL in leukemic cells as a prognostic parameter pending prospective validation. TL in nonleukemic myeloid cells seems unaffected even by long-term TKI treatment arguing against a reduction of telomere-mediated replicative reserve in normal hematopoiesis under TKI treatment.
  • Pfirrmann, Markus; Clark, Richard E.; Prejzner, Witold; Lauseker, Michael; Baccarani, Michele; Saussele, Susanne; Guilhot, Francois; Heibl, Sonja; Hehlmann, Rudiger; Faber, Edgar; Turkina, Anna; Ossenkoppele, Gert; Hoglund, Martin; Zaritskey, Andrey; Griskevicius, Laimonas; Olsson-Stromberg, Ulla; Everaus, Hele; Koskenvesa, Perttu; Labar, Boris; Sacha, Tomasz; Zackova, Daniela; Cervantes, Francisco; Colita, Adriana; Zupan, Irena; Bogdanovic, Andrija; Castagnetti, Fausto; Guilhot, Joelle; Hasford, Joerg; Hochhaus, Andreas; Hoffmann, Verena S. (2020)
    Prognostic scores support clinicians in selecting risk-adjusted treatments and in comparatively assessing different results. For patients with chronic-phase chronic myeloid leukemia (CML), four baseline prognostic scores are commonly used. Our aim was to compare the prognostic performance of the scores and to arrive at an evidence-based score recommendation. In 2949 patients not involved in any score development, higher hazard ratios and concordance indices in any comparison demonstrated the best discrimination of long-term survival with the ELTS score. In a second step, of 5154 patients analyzed to investigate risk group classification differences, 23% (n = 1197) were allocated to high-risk by the Sokal score. Of the 1197 Sokal high-risk patients, 56% were non-high-risk according to the ELTS score and had a significantly more favorable long-term survival prognosis than the 526 high-risk patients according to both scores. The Sokal score identified too many patients as high-risk and relatively few (40%) as low-risk (versus 60% with the ELTS score). Inappropriate risk classification jeopardizes optimal treatment selection. The ELTS score outperformed the Sokal score, the Euro, and the EUTOS score regarding risk group discrimination. The recent recommendation of the European LeukemiaNet for preferred use of the ELTS score was supported with significant statistical evidence.
  • Schubert, Claudia; Chatain, Nicolas; Braunschweig, Till; Schemionek, Mirle; Feldberg, Kristina; Hoffmann, Melanie; Dufva, Olli; Mustjoki, Satu; Bruemmendorf, Tim H.; Koschmieder, Steffen (2017)
    The second generation tyrosine kinase inhibitor (TKI) dasatinib is a clinically approved drug for chronic myeloid leukemia (CML) as well as Ph+ acute lymphoblastic leukemia. In addition to its antileukemic effects, dasatinib was shown to impact on normal hematopoiesis and cells of the immune system. Due to the fact that the murine in vivo studies so far have not been performed in a chronic-phase CML model under steady-state conditions, our aim was to study the hematopoietic effects of dasatinib (20 mg/kg p.o.) in BCR-ABL expressing SCLtTAxBCR-ABL double transgenic (dtg) mice. Dasatinib robustly antagonized the CML phenotype in vivo in our transgenic mouse model, and this effect included both mature and immature cell populations. However, similar to patients with CML, the fraction of Lin(neg)Sca-1(+)KIT(+)CD48(neg)CD150(+) hematopoietic stem cells was not reduced by dasatinib treatment, suggesting that these cells are not oncogene-addicted. Moreover, we observed differential effects of dasatinib in these animals as compared to wild-type (wt) animals: while granulocytes were significantly reduced in dtg animals, they were increased in wt mice. And Ter119(+) erythrocytic and B220(+) B cells were increased in dtg mice but decreased in wt mice. Finally, while dasatinib induced a shift from CD49b/NK1.1 positive NK cells from the bone marrow to the spleen in wt animals, there was no change in dtg mice. In conclusion, the present mouse model provides a useful tool to study mechanisms of TKI resistance and dasatinib-associated beneficial effects and adverse events.
  • Koskela, Hanna L. M.; El Missiry, Mohamed; Ruusila, Anniina; Koskenvesa, Perttu; Bruemmendorf, Tim H.; Gjertsen, Bjorn T.; Janssen, Jeroen; Lotfi, Kourosh; Markevarn, Berit; Olsson-Stromberg, Ulla; Stenke, Leif; Stentoft, Jesper; Richter, Johan; Hjorth-Hansen, Henrik; Kreutzman, Anna; Mustjoki, Satu (2017)
    Purpose Tyrosine kinase inhibitors (TKIs) have well-characterized immunomodulatory effects on T and NK cells, but the effects on the humoral immunity are less well known. In this project, we studied TKI-induced changes in B cell-mediated immunity. Methods We collected peripheral blood (PB) and bone marrow (BM) samples from chronic myeloid leukemia (CML) patients before and during first-line imatinib (n = 20), dasatinib (n = 16), nilotinib (n = 8), and bosutinib (n = 12) treatment. Plasma immunoglobulin levels were measured, and different B cell populations in PB and BM were analyzed with flow cytometry. Results Imatinib treatment decreased plasma IgA and IgG levels, while dasatinib reduced IgM levels. At diagnosis, the proportion of patients with IgA, IgG, and IgM levels below the lower limit of normal (LLN) was 0, 11, and 6% of all CML patients, respectively, whereas at 12 months timepoint the proportions were 6% (p = 0.13), 31% (p = 0.042) and 28% (p = 0.0078). Lower initial Ig levels predisposed to the development of hypogammaglobulinemia during TKI therapy. Decreased Ig levels in imatinibtreated patients were associated with higher percentages of immature BM B cells. The patients, who had low Ig levels during the TKI therapy, had significantly more frequent minor infections during the follow-up compared with the patients with normal Ig values (33% vs. 3%, p = 0.0016). No severe infections were reported, except recurrent upper respiratory tract infections in one imatinib-treated patient, who developed severe hypogammaglobulinemia. Conclusions TKI treatment decreases plasma Ig levels, which should be measured in patients with recurrent infections.