Search

PLAIN LANGUAGE SUMMARY What is the context? After haematopoletic stem cell transplantation, patlents have impaired immunity from conditioning chemotherapy regimens, often exacerbated by underlying diseases, putting them at high risk of developing herpes zoster. In this population, antiviral prophylaxis is the current standard of care to reduce herpes zoster risk. Vaccination provides an additional means to prevent herpes zoster. Live-attenuated vaccines are generally contraindicated in immuonocompromised patients. A non-live, adjuvanted recombinant zoster vaccine (RZV, Shingrix, GSK), has been approved for use in adults 250 years of age in the European Union, United States, Canada, Australia, Japan, and China. This vaccine is highly efficacious at preventing herpes zoster in adults over 50 years of age, as demonstrated in large, placebo-controlled randomised trials. Importantly, Shingrix use is not contraindicated in immunocompromised conditions, and was found to be highly efficacious in adults who had recently undergone autologous haematopoleticstem cell transplant. What is new? In autologous haematopoietic stem cell transplant recipients in whom Shingrix has demonstrated efficacy, two doseselicited high and persistent immune responses. Date presented here further support our understanding of the impact of specific factors such as age or underlying diseases on the vaccine's effect in the population studies, as well as the characteristics of the elicited cell-mediated immune responses. What is the impact? These results indicate that Shingrix, given shortly after haematopoletic stem cell transplant, can induce robust immune responses and reduce the risk of herpes zoster, even in individuals with immunosuppression due to underlying disease and/or use of immunosuppressive therapies, regardless of age or underlying disease. Immunocompromised individuals, particularly autologous hematopoietic stem cell transplant (auHSCT) recipients, are at high risk for herpes zoster (HZ). We provide an in-depth description of humoral and cell-mediated immune (CMI) responses by age (protocol-defined) or underlying disease (post-hoc) as well as efficacy by underlying disease (post-hoc) of the adjuvanted recombinant zoster vaccine (RZV) in a randomized observer-blind phase III trial (ZOE-HSCT, NCT01610414). 1846 adult auHSCT recipients were randomized to receive a first dose of either RZV or placebo 50-70 days post-auHSCT, followed by the second dose at 1-2 months (M) later. In cohorts of 114-1721 participants, at 1 M post-second vaccine dose: Anti-gE antibody geometric mean concentrations (GMCs) and median gE-specific CD4[2+] T-cell frequencies (CD4 T cells expressing >= 2 of four assessed activation markers) were similar between 18-49 and >= 50-year-olds. Despite lower anti-gE antibody GMCs in non-Hodgkin B-cell lymphoma (NHBCL) patients, CD4[2+] T-cell frequencies were similar between NHBCL and other underlying diseases. The proportion of polyfunctional CD4 T cells increased over time, accounting for 79.6% of gE-specific CD4 T cells at 24 M post-dose two. Vaccine efficacy against HZ ranged between 42.5% and 82.5% across underlying diseases and was statistically significant in NHBCL and multiple myeloma patients. In conclusion, two RZV doses administered early post-auHSCT induced robust, persistent, and polyfunctional gE-specific immune responses. Efficacy against HZ was also high in NHBCL patients despite the lower humoral response., GlaxoSmithKline Biologicals SA, This work was sponsored by GlaxoSmithKline Biologicals SA in all stages of the study conduct and analysis. GlaxoSmithKline Biologicals SA also took responsibility for all costs associated with the development and publishing of the present manuscript.

As novel immunological treatments are gaining a foothold in the treatment of acute lymphoblastic leukemia (ALL), it is elemental to examine ALL immunobiology in more detail. We used multiplexed immunohistochemistry (mIHC) to study the immune contexture in adult precursor B cell ALL bone marrow (BM). In addition, we developed a multivariate risk prediction model that stratified a poor survival group based on clinical parameters and mIHC data. We analyzed BM biopsy samples of ALL patients (n = 52) and healthy controls (n = 14) using mIHC with 30 different immunophenotype markers and computerized image analysis. In ALL BM, the proportions of M1-like macrophages, granzyme B+CD57+CD8+ T cells, and CD27+ T cells were decreased, whereas the proportions of myeloid-derived suppressor cells and M2-like macrophages were increased. Also, the expression of checkpoint molecules PD1 and CTLA4 was elevated. In the multivariate model, age, platelet count, and the proportion of PD1+TIM3+ double-positive CD4+ T cells differentiated a poor survival group. These results were validated by flow cytometry in a separate cohort (n = 31). In conclusion, the immune cell contexture in ALL BM differs from healthy controls. CD4+PD1+TIM3+ T cells were independent predictors of poor outcome in our multivariate risk model, suggesting that PD1 might serve as an attractive immuno-oncological target in B-ALL.

Background Heparin-induced thrombocytopenia (HIT) usually appears at 5 to 10 days after initiation of heparin. Autoimmune HIT can arise after discontinuation of heparin treatment (delayed-onset HIT) or without any preceding heparin exposure (spontaneous HIT syndrome). Case report This case presents a course of autoimmune HIT with delayed onset. The patient was hospitalized due to influenza pneumonia and received low-molecular-weight heparin thromboprophylaxis for 9 days. Seven days after discharge, she was readmitted because of a cerebral sinus vein thrombosis and severe thrombocytopenia. Intracranial bleeding and brain infarction caused her death. Discussion Autoimmune HIT was confirmed by functional heparin-induced platelet (PLT) activation test. Intracranial bleeding prevented continuous and effective anticoagulation. PLT transfusions were given, although they are generally advised against in HIT patients due to potential risk of thromboembolic events. Conclusion This case presents that testing PLT-activating antibodies both in the presence and in the absence of current heparin treatment helps to diagnose patients with autoimmune HIT. There is conflicting evidence to refuse PLT transfusion when HIT is complicated with life-threatening bleeding.

Patients with chronic lymphocytic leukemia (CLL) are at a high risk for infections caused by Streptococcus pneumoniae. A pneumococcal conjugate vaccine (PCV) can induce a significant antibody response for some CLL patients. In this study we investigated antibody persistence after PCV7 in patients with CLL. The study material comprised 24 patients with CLL and 8 immunocompetent controls. The median antibody concentrations five years after PCV7 were lower for six pneumococcal serotypes in patients with CLL compared to controls, but the difference was not statistically significant. Depending on the serotype, the percentage of the CLL patients with antibody levels suggested to provide protection against invasive pneumococcal disease (IPD) varied from 29 to 71% five years after vaccination. This data suggests that PCV could result in antibody persistence at least five years in CLL patients.

The 23-valent pneumococcal polysaccharide vaccine (PPV23) given alone is ineffective in patients with chronic lymphocytic leukemia (CLL) and better antibody response is achieved with pneumococcal conjugate vaccines (PCVs). In this study, we determine whether CLL patients would achieve a significant antibody response and broaden their serotype coverage against invasive pneumococcal disease (IPD) with PPV23 given five years after the 7-valent conjugate vaccine (PCV7). A total of 24 patients with CLL and eight controls were vaccinated with PPV23 five years after PCV7. Blood samples for evaluation of antibody response to PCV7 serotypes and PPV23 serotypes 5 and 7 were taken before vaccination and one month after it. Post-vaccination samples were available from 20 patients. IgG antibodies were measured with ELISA. Antibody concentrations after PPV23 were significantly lower in CLL patients for six of the PCV7 serotypes and for both PPV23 serotypes. Only 10% to 15% of CLL patients achieved an antibody response suggested to be protective against IPD. Hence, PCV7 given five years before PPV23 did not improve antibody response in patients with CLL. Based on our results, PPV23 given after a PCV primer is not useful against IPD in CLL patients.

The baseline national invasive pneumococcal disease (IPD) incidence rate, serotype distribution and serotype coverage of pneumococcal vaccines were evaluated in patients with Hodgkin's and non-Hodgkin's lymphomas, myeloma and leukaemia within 1 year after haematological diagnosis during 1995-2002, before introduction of pneumococcal conjugate vaccines. Pneumococcal serotype distribution among these patients was different from serotypes causing IPD in the general population. The serotype coverages of PCV13 and PPSV23 were 57% and 64%, respectively, lower than in the general population. This reflects a higher predisposition to IPD in vaccinated patients with haematological malignancies and possibly less benefit of herd immunity gained with the wide use of pneumococcal conjugate vaccines in the general population. This data will be useful as a baseline for determining the future role of adult PCV vaccination in these patient groups.

Biologic and clinical observations suggest that combining imatinib with IFN-α may improve treatment outcome in chronic myeloid leukemia (CML). We randomized newly diagnosed chronic-phase CML patients with a low or intermediate Sokal risk score and in imatinib-induced complete hematologic remission either to receive a combination of pegylated IFN-α2b (Peg–IFN-α2b) 50 μg weekly and imatinib 400 mg daily (n = 56) or to receive imatinib 400 mg daily monotherapy (n = 56). The primary endpoint was the major molecular response (MMR) rate at 12 months after randomization. In both arms, 4 patients (7%) discontinued imatinib treatment (1 because of blastic transformation in imatinib arm). In addition, in the combination arm, 34 patients (61%) discontinued Peg–IFN-α2b, most because of toxicity. The MMR rate at 12 months was significantly higher in the imatinib plus Peg–IFN-α2b arm (82%) compared with the imatinib monotherapy arm (54%; intention-to-treat, P = .002). The MMR rate increased with the duration of Peg–IFN-α2b treatment (< 12-week MMR rate 67%, > 12-week MMR rate 91%). Thus, the addition of even relatively short periods of Peg–IFN-α2b to imatinib markedly increased the MMR rate at 12 months of therapy. Lower doses of Peg–IFN-α2b may enhance tolerability while retaining efficacy and could be considered in future protocols with curative intent.

Early identification of patients at risk of a severe course of hantaviral disease and lack of effective medication represent a global challenge in the treatment of this emerging infection. We describe a 67-year-old female patient with a history of chronic lymphoproliferative disease involving the spleen and an extremely severe acute Puumala hantavirus infection. She was treated with the bradykinin receptor antagonist icatibant and recovered. She is the second patient with a spleen abnormality and severe Puumala infection treated with icatibant in our hospital. We suggest that patients with spleen abnormalities may be more susceptible to severe hantavirus disease. The activation of the kinin-kallikrein system and the formation of bradykinin in hantavirus-infected endothelial cells indicate that the role of bradykinin receptor antagonist icatibant in the treatment of hantavirus disease is worth studying.

Chronic lymphocytic leukemia (CLL) is a clonal B-cell disorder, which has recently been divided into 2 subtypes based on the somatic hypermutation status of the immunoglobulin heavy chain (IgVH) genes. In patients with unmutated tumor cells the survival time is approximately half of that in mutated cases, but the reason for this difference is poorly understood. Since infections are the major cause of mortality in CLL, we investigated the effect of the mutation status on host immunity and proneness to infections in patients with CLL. As expected, the disease progression seemed to be faster and the disease more advanced (Binet B and C) among unmutated patients than in the mutated ones. Surprisingly, no differences in humoral immunity [immunoglobulin G (IgG), IgM, IgA, IgG subclasses, anti-ABO blood group antibodies and mannan-binding lectin (MBL)] or immune responses (Haemophilus influenzae serotype b conjugate vaccination) were detected between these 2 patient groups. Furthermore, UM-patients were not more prone to infections compared to M-patients, and therapy had no impact on the incidence and pattern of infections in either of the patient groups. The current findings within this patient cohort reveal that the worse outcome in the unmutated subgroup is not caused by more severe defects in immunity and increased susceptibility to infections when compared with the hypermutated group. It is thus conceivable that active immunization procedures such as vaccination can successfully be applied on patients with unmutated IgVH gene and advanced disease stage.

We investigated responses to vaccination against pneumococcal polysaccharide, Haemophilus influenzae b (Hib) conjugate and tetanus toxoid antigens in 31 patients with chronic lymphocytic leukaemia (CLL) and 25 controls. While in the control group all antibody responses against different antigens were highly significant, in the patient group clear evidence for responsiveness was detected only in the case of Hib polysaccharide antigen. Certain CLL patient subgroups showed low reactivity against tetanus toxoid antigen. In conclusion, plain polysaccharide vaccines seem to be ineffective in patients with CLL. Conjugate vaccines, in turn, are immunogenic and may offer protection against infections caused by encapsulated bacteria in these patients. Further studies concerning an optimal vaccination scheme and clinical efficiency are warranted.

We investigated the influence of plasma concentrations of immunoglobulin G (IgG), IgA, IgM, IgG subclasses and mannan-binding lectin (MBL) on susceptibility to infection in patients with chronic lymphocytic leukemia (CLL). Of 28 patients with CLL, increased susceptibility to infection was recorded in nine. Four of them (44%) had hypogammaglobulinemia as opposed to only one (5%) of the 19 patients without increased susceptibility to infection (OR 14.4; 95% CI, 1.6-130). When the effect of IgG subclasses contributing to hypogammaglobulinemia was studied, only the decreased concentrations of IgG4 and IgG2 were associated with increased susceptibility to infection. They, in turn, were intercorrelated and also highly correlated with the concentration of IgA. In fact, when these parameters were studied by a multivariable model, only the decreased concentration of IgA was shown as an independent risk factor for infection (P = 0.03). The mean concentration of MBL was significantly higher in patients with infections than in those without (6.54 mg/l and 2.75 mg/l, respectively; P = 0.001). The monitoring of its concentrations might be useful in the follow-up of infectious morbidity in CLL.

Somatic mutations in exons 1 and 2 of the Mediator complex subunit 12 (MED12) have been identified in 70% of uterine leiomyomas, 7-20% of uterine leiomyosarcomas, 59% of breast fibroadenomas and 67% of breast phyllodes tumors. In addition to female hormone-dependent tumors we have recently found the same specific missense and small in-frame insertion and deletion mutations in approximately 5% of chronic lymphocytic leukemias (CLL). In CLL the presence of MED12 mutations was also associated with markers of poor prognosis (IgVH (-), Zap70 (+), and Zap70-methylation). The surprising finding of the same mutations in a completely different tumor type prompted us to further screen other hematological malignancies for MED12 mutations. We have thus far collected samples of 107 T-cell acute lymphoblastic leukemias (T-ALL), 21 large granular lymphocyte leukemias (LGL), 33 acute myeloid leukemias (AML), 154 diffuse large B cell lymphomas (DLBCL), and 6 six follicular lymphomas (FL). Also a set of 30 additional CLLs was collected. The MED12 mutation status was determined by direct Sanger sequencing of exons 1 and 2 of the gene. A c.107T>G, p.L36R mutation was found in a single DLBCL case and c.100-8T>A, p.E33_D34insPQ in one AML sample. A novel variant of uncertain significance, c.-3A>G, was detected on 5’UTR of one FL sample. One T-ALL patient harbored a nonsense mutation affecting the last codon of exon 1 c.97G>T, p.E33X. No mutations were identified in the LGL or CLL samples. We are also analyzing approximately 100 new AML samples and 100 multiple myeloma samples. MED12 mutations are present, in addition to CLL, also in other hematological malignancies. The frequency, however, seems to be low and, as the number of samples in the preliminary analysis is limited, screening of larger sample sets is needed. The c.107T>G, p.L36R and c.100-8T>A, p.E33_D34insPQ mutations have previously been detected recurrently in uterine leiomyomas and in CLL. Further studies are required for evaluation of the effects of c.-3A>G and c.97G>T, p.E33X mutations. The latter mutation affects the last codon of exon 1, which is also a mutational hotspot in CLL, with recurrent missense mutations. MED12 exon 1 and 2 missense mutations disrupt the interactions between the Mediator complex and Cyclin C and cause loss of CDK8 kinase activity. Studies to determine the impact of the c.97G>T, p.E33X mutation on MED12 function are ongoing. Citation Format: Tuomas Heikkinen, Kati Kämpjärvi, Sirpa Leppä, Peter Hokland, Heikki Kuusanmäki, Satu Mustjoki, Marjatta Sinisalo, Caroline Heckman, Mika Kontro, Pia Vahteristo. Somatic MED12 mutations in hematological malignancies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1169.

We have recently demonstrated a moderate vaccination response rate of 43% against Haemophilus influenzae type b (Hib) conjugate vaccine among adult and elderly patients with chronic lymphocytic leukaemia (CLL). We now investigated demographic and immunological factors predicting the favourable response and protective antibody concentrations for Hib conjugate vaccine in CLL. Lower age was associated with protective pre- and post-vaccination antibody concentrations. High IgG1 and IgA concentrations were also associated with the protective efficacy. High IgM, in turn, was the best predictor of a significant vaccination response. Again, lower age seemed to be involved in this outcome. Judging from these findings, it would seem beneficial to vaccinate all CLL patients with conjugate vaccines at the presentation of the disease. Investigations of a new pneumococcal conjugate vaccine in CLL are warranted.

Indoleamine 2,3-dioxygenase (IDO) activity and expression is increased in many hematological malignancies, but has not been previously studied in chronic lymphocytic leukemia (CLL). We determined IDO activity and expression in 49 patients with CLL. We found that IDO activity is increased in CLL. This may have some influence on CLL progression.Indoleamine 2,3-dioxygenase (IDO) is an enzyme involved in the catabolism of tryptophan, suppressing T-cell activity. IDO activity and expression are increased in many malignant diseases, including hematological malignancies. IDO expression can mediate immunotolerance to tumors. IDO activity and expression have not previously been studied in chronic lymphocytic leukemia (CLL).We measured IDO activity by calculating the kynurenine-tryptophan (kyn-trp) ratio. IDO and IDO2 gene expression was determined by using real-time polymerase chain reaction (PCR).In patients with CLL, the serum kyn-trp ratio--reflecting increased IDO activity--was significantly higher compared with controls, but in peripheral blood mononuclear cells (PBMCs)--mainly representing malignant B cells--the expression of genes encoding IDO and IDO2 enzymes was reduced.Increased IDO activity in patients with CLL may affect disease progression, although it originates from cells other than malignant B cells.

Chronic lymphocytic leukaemia (CLL) is a common adulthood mature B-cell neoplasm. Infections are the most important cause of mortality in this condition, and Streptococcus pneumoniae has been considered the most important single pathogen. We investigated the immunogenicity of 7-valent pneumococcal conjugate vaccine in patients with CLL. The study material comprised 52 patients with CLL and 25 age- and sex-matched controls. The subjects were vaccinated with Prevenar® pneumococcal conjugate vaccine. Serum samples were taken for antibody determinations before and four weeks after vaccination. Antibody response rates to vaccine antigens were lower in patients with CLL compared to controls. However, if the vaccine had been administered at an early stage of the disease, i.e. before commencement of chemotherapy and the development of hypogammaglobulinaemia, a significant vaccination response to at least six antigens was obtained in almost 40% of the CLL patients. Our results indicate that early administration of conjugate vaccine may be beneficial in CLL.

Chronic lymphocytic leukemia (CLL) is a well-defined mature B-cell neoplasm associated with increased susceptibility to infections. Two major options in prevention of infections in CLL, intravenous gammaglobulin treatment and antimicrobial chemoprophylaxis, have not resulted in satisfactory outcome. A third strategy, antimicrobial vaccination, is the topic of this minireview. We collected articles and their references concerning CLL vaccination from the Medline database starting from 1966 and thirteen relevant studies were found. Plain bacterial polysaccharide vaccines would seem to be ineffective in antibody formation in patients with CLL. However, protein and conjugate vaccines appear to be more immunogenic and their responses may be further enhanced with ranitidine adjuvant treatment. New well-designed investigations are needed to develop appropriate vaccination strategies and evaluate vaccination efficacy in infection morbidity and mortality in CLL.

The second-generation thrombopoietin receptor (TPO-R) agonists (romiplostim and eltrombopag) were introduced in the treatment of chronic immunologic thrombocytopenia (ITP) approximately 2 years ago...

Abstract 1201 Background. Before the era of tyrosine kinase inhibitors (TKIs), interferon alpha (IFN-α) was the treatment of choice in CML and prolonged survival of responding patients. Recent studies suggest that combination of IFN-α with TKI improves therapy outcome. Significantly, a proportion of IFN-α treated patients in prolonged complete cytogenetic remission (CCyR) have been able to discontinue treatment without disease relapse (Mahon et al. JCO 2002). The mechanism of action of IFN-α therapy is incompletely understood; the drug exerts both direct cytotoxic and immunomodulatory effects on leukemic cells. The aim of this project was to study the immunomodulatory effects of IFN-α in CML patients in prolonged remission and isolate biological markers predicting response. Patients and methods. The study population consisted of CML patients treated with IFN-α monotherapy (n = 10, median therapy time 146 months, range 63–231 months) and CML patients who had discontinued IFN-α therapy but remained in remission for >2 years (n = 9, median therapy time 120 months, range 80–184; median time without therapy 53 months, range 24–96). None of the patients were previously treated with TKI therapy. In addition, non-CML patients (3 patients with essential trombocythemia and one patient with polycythemia vera) treated with IFN-α and healthy volunteers (n = 43) were included as controls. Lymphocyte populations in all four groups were characterized with comprehensive immunophenotyping panels. The clonality of T-cells was analyzed by a TCR γ/δ rearrangement assay by PCR. Lymphocytes were further sorted into CD3+ TCR αβ+ and CD3+ TCR γδ+ populations (n = 8). Additionally, plasma levels of 25 cytokines were measured with a multiplex bead-based cytokine assay (Luminex®). Results. The proportion of NK-cells from lymphocytes was significantly increased in IFN-α discontinued patients (median 26%, range 18–51%) compared to healthy volunteers (11%, 5–21%) or patients on IFN-α therapy (12%, 6–31%)(P=0.0005). Similarly the proportion of CD8+ cells from T-cells was significantly increased in both CML IFN-α groups (55% in IFN-α discontinued patients, 44% in IFN-α treated patients vs. 31% in healthy volunteers; P Clonal TCR γ/δ rearrangements were observed in 18 of 19 (95%) IFN-treated CML patients as compared to 3 of 22 (14%) in healthy volunteers (P IFN-α treatment was associated with a distinct plasma cytokine profile in CML patients. IP-10, IL-6, IL-12, eotaxin, MCP-1, and IFN-γ levels were significantly increased in IFN-α treated CML patients. In particular, eotaxin and MCP-1 levels differed significantly between healthy controls and IFN-α patients who had successfully discontinued IFN-α therapy (428 vs. 1173 pg/ml, P Conclusions. Our results show that IFN-α treatment induces distinct changes in the immunoprofile of CML patients. Patients who had successfully discontinued IFN-α therapy differed markedly from healthy controls. IFN-α therapy was associated with increased numbers of NK-cells and clonal γδ+ T-cells. These cells possess potent anti-leukemic activity and may contribute to the prolonged therapy responses in this group of patients. Furthermore, plasma cytokine profile could be a helpful biomarker when considering which patients can discontinue the IFN-α treatment without imminent disease relapse. Disclosures: Faber: BMS, Novartis: Consultancy, Honoraria. Porkka:BMS, Novartis: Consultancy, Honoraria, Research Funding. Mustjoki:BMS, Novartis: Honoraria.

Abstract 3280 Poster Board III-1 Background: Imatinib mesylate (IM) 400 mg once daily (OD) is the current standard first-line therapy for CML. Several biological and clinical observations suggest that combining IM with interferon alpha (IFNa) may improve the outcome of treatment. Aim: To compare the effects of standard-dose IM to combination of IM and IFNa in newly diagnosed chronic phase CML patients with an intermediate or low Sokal risk score. The primary end point was to compare the major molecular response (MMR) rate after 12 months between the treatment arms (intention-to-treat analysis). Patients and therapies: In a Nordic CML Study Group (NMCLSG: Denmark, Finland, Norway and Sweden) and Israel multicenter study we randomized 114 newly diagnosed CML patients in complete hematological remission following 3 months of IM 400 mg OD induction therapy. The study arms were IM (Glivec, Novartis) and the combination of IM and IFNa 2b (PegIntron, Schering-Plough). IM dose was fixed at 400 mg OD. IFNa was started at 30 μg/week but could be escalated to 50 μg/week or reduced down to 15 μg/week depending on tolerability. Molecular response was evaluated by blood RQ-PCR for BCR-ABL1 and was expressed on the international scale (IS). Results: As of August 17, 2009, 79 patients were evaluable for primary endpoint and 47 of these were in MMR (59%) The rate of complete cytogenetic response (CCgR) was 68/79 (86%). Nineteen patients (17%) were considered as treatment failures (grade 4 nonhematological adverse event, refusal, loss of CCgR, progression to advanced phase, protocol violation or other reason). Conclusions: A final analysis will be performed when we have complete data on all randomized patients. The comparison by treatment arm on molecular and cytogenetic responses as well as other relevant data (treatment failures, patients off-treatment for protocol violations, refusal or toxicity) will be presented on site. Supported by European LeukemiaNet, WP 4. Disclosures: Simonsson: Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding. BjÖreman:BMS: Consultancy, Honoraria. Mustjoki:BMS: Honoraria. StrÖmberg:Novartis: Honoraria; BMS: Honoraria. Weiss Bjerrum:Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria. Gruber:Novartis: Research Funding. Nagler:Novartis: Consultancy. Porkka:Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding.

Tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL fusion protein are an effective therapy for Philadelphia chromosome positive (Ph+) leukemia. Dasatinib, a 2nd generation pan-TKI, also inhibits wild-type kinases, which may result in unexpected clinical responses. Recent data suggest that dasatinib has a potent immunosuppressive effect on T- and NK-cells in vitro. In contrast, we have noticed a marked expansion of lymphocytes in blood in a subset of dasatinib patients, but its clinical significance and molecular mechanisms are unclear. In this multicenter study, 19 Ph+ leukemia patients with marked lymphoproliferation in blood while on dasatinib (9 CML CP, 2 CML AP, 2 CML BC, 6 Ph+ALL) were identified. Clonality, immunophenotype, and intracellular signaling was analyzed and related clinical information was collected. In addition, prevalence and prognostic significance of the phenomenon was retrospectively assessed in a Phase II clinical study on 46 Ph+ ALL patients. An abrupt lymphocytosis (peak count range 4–20×109/L) with large granular lymphocyte (LGL) morphology was observed after a median of 3 months from the start of therapy (range 1–8 months). In most patients, LGL lymphocytosis was long-lasting and continued throughout dasatinib therapy, albeit with marked fluctuations in absolute lymphocyte count (Fig. 1a). In all evaluable patients (n=4), lymphocyte counts normalized after drug discontinuation. All patients were previously exposed to imatinib without similar changes in lymphocyte count or morphology. By immunophenotyping, 14 patients had a cytotoxic T-cell and 5 patients a NK-cell phenotype. After initiation of dasatinib therapy, the CD4/CD8 ratio shifted, expression of activation antigens HLA-DR and CD57 increased, expression of homing antigen CD62L decreased and relative numbers of regulatory T-cells were significantly decreased (p Figure Figure

In addition to therapeutic efficacy in imatinib-resistant BCR-ABL positive malignancies, dasatinib may have off-target immunomodulatory effects by inhibiting kinases (e.g. SRCs, c-KIT) in immune effector cells. In a proportion of patients, dasatinib treatment is associated with non-infectious pleural effusions and panniculitis, which may reflect aberrant immune reactivity. Here we describe a marked expansion of clonal LGL lymphocytes in blood among 11 BCR-ABL positive patients on dasatinib therapy (5 CML CP, 1 CML AP, 1 CML BC, 4 Ph+ALL). All patients were previously exposed to imatinib without similar changes in lymphocyte count or morphology. The median time to LGL lymphocytosis was 2 months from the start of dasatinib (range 1–8 months). It developed abruptly, with a peak lymphocyte count of 4–20 ×109/L, and was often preceded by low-grade fever. In all evaluable cases, lymphocyte counts normalized after drug discontinuation. By immunophenotyping, 6 patients had a CD3/CD8+ cytotoxic T-cell phenotype and 4 patients had a CD56+ NK-cell phenotype. The LGL lymphocytes were BCR-ABL negative. All CD3-positive cases had a clonal rearrangement of TCR gamma/delta genes by PCR; clonality was not detected in samples prior to dasatinib therapy (n=3). In TCR beta gene repertoire assay, oligoclonal patterns were seen in selected genes. All patients with HLA data had the A2 allele (n=8). Dasatinib-related complications were common: pleural effusions and/or pulmonary infiltrates (n=8), modest CMV reactivation (n=5), severe colitis (n=5), which developed after appearance of LGL lymphocytosis. Immunophenotyping was available from 2 patients with pleural effusions: in both cases the majority of cells were CD3+CD8+ T-cells and no leukemic cells were detected. TCR gamma assay was done from one patient sample and it showed similar clonal pattern as in peripheral blood. However, despite frequent side-effects, response to dasatinib treatment was very good in all cases, including complete molecular responses in 5 advanced phase patients. Transient clonal LGL lymphocytosis has been described in few patient cases with a primary herpesvirus infection. Our patients share striking pheno/genotypic similarities with LGL leukemia, in which an antigen driven expansion of LGLs precedes the occurrence of oncogenic events. However, in our patients LGL lymphocytosis appeared to be a benign phenomenon. We postulate that by virtue of inhibition of key non-BCR-ABL kinases, dasatinib induces a reversible state of autoimmune-like reactivity upon antigen challenge in a proportion of patients with a distinct genetic and/or environmental background. The aberrant immune response may also result in enhanced anti-leukemic control driven by the cytotoxic T/NK LGL cells. Dasatinib could be a valuable tool in uncovering the pathogenesis of LGL lymphoproliferation, putatively related to mutations in kinases targeted by the drug.

Introduction Tyrosine kinase inhibitors (TKIs) such asimatiniband dasatinib have markedly improved treatment results in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL). Almost all patients achieve at least a complete hematological remission with induction therapy consisting of TKImonotherapyor TKI in combination with reduced-intensity chemotherapy and corticosteroids. In eligible patients, allogeneic hematopoietic stem cell transplantation (alloHSCT) has been recommended in first complete remission, but its role inpatientsachieving rapid and deep molecular remissions with TKI-driven therapy is unresolved. Methods We analyzed data fromPh+ ALL patients in the Finnish Hematological Registry (FHR), a population-based database maintained by the Finnish Hematology Association, which includes patients participating in clinical study protocols sponsored by theTheFinnish Leukemia Group, and patients treated outside of clinical trials. The FHR contains detailed information on baseline (demographics, laboratory values,cytogenetics, molecular assays) and follow-up (therapies given and outcome). Minimal residual disease (MRD) was evaluated by standardized RQ-PCR for the bone marrow BCR-ABL1 transcripts with a minimum sensitivity of 10e-5. Therapy responses were coded according to the EuropeanLeukemiaNetguidelines. Data from 128Ph+ALLpatients diagnosed between 1983-2016 were included in the analyses. Survival outcomes were calculated with the Kaplan-Meier method and compared with the log-rank test. Differences between groups were evaluated with the independent samples t-test for parametric numeric variables. Results Of the 128 patients included in the analyses, 78 patients (61%) had received TKI treatment and 50 patients were treated prior the TKI era. The TKIs used wereimatiniband dasatinib and majority of patients concurrently received combination chemotherapy for induction and consolidation. Of the patients not treated with TKIs, 19/50 (38%) received an allotransplant and the overall survival (OS) at 5 years was 58% in the allotransplanted vs. 3% in thenontransplantedpatients (P Discussion Our data indicate that up to 50% of patients withPh+ALLexperience long-term survival with TKI-driven therapy and noalloHSCT. However, robust predictive biomarkers are needed for selecting patients in whom the treatment-related mortality and morbidity ofalloHSCTare not warranted and could be treated with TKI-driven therapies only. MRD-negativity at 3 months may select for better outcome, but larger studies are needed for confirmation. In addition, disease-specific genomic andtranscriptomicprofiles (e.g. IKZF1, CDKN2 mutations) andimmunoreconstitutionmay prove valuable in this context. The advent of novel potent MRD-eradicating agents, such asbispecificCD3/CD19 antibodies, may further indicate re-evaluation of the role ofalloHSCTinPh+ALL. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures Mustjoki: Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Ariad: Research Funding. Säily:Celgene: Other: Educational grant for congress participation; Amgen: Other: Educational grant for congress participation. Remes:Teva: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees. Porkka:Celgene: Research Funding.