Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    In: Blood, American Society of Hematology, Vol. 106, No. 11 ( 2005-11-16), p. 2905-2905
    Abstract: Donor-recipient incompatibility for human leukocyte antigen (HLA) ligands of killer cell immunoglobulin-like receptors (KIRs) in haploidentical hematopoietic stem cell transplantation (HSCT), has been associated with a selective graft versus leukemia (GvL) effect mediated by donor-derived alloreactive natural killer (NK) cells expressing KIRs whose ligands are missing in the recipient. In this study, we show that NK cells arising from hematopoietic stem cell progenitors after transplantation into haploidentical recipients, acquire a receptor repertoire that is compatible with patient-specific tolerance due to engagement of patient HLA ligands by inhibitory NK receptors. Using four-color immunofluorescence with monoclonal antibodies (mAbs) specific for the receptors CD94/NKG2A, KIR2DL1/2DS1, KIR2DL2/2DL3/2DS2 and KIR3DL1, we have analyzed NK receptor reconstitution kinetics in eleven adult patients affected by acute myeloid (n=9) or lymphoblastic (n=2) leukemia, who underwent HSCT from a KIR ligand matched (n=5) or mismatched (n=6) haploidentical family donor, using high doses (median 12.5x106/kg) of purified CD34+ progenitors. Nine patients achieved long-term ( & gt;150 days) complete remission of disease, independently from disease status at time of transplantation, and, importantly, from the presence (n=5) or absence (n=4) of donor NK alloreactivity. Within the first two months after transplantation, the vast majority (96% at 30 days, 86% at 60 days; SD 2% and 11%, respectively) of NK cells arising in the patients expressed the inhibitory receptor CD94/NKG2A, whose ligand HLA-E is ubiquitously expressed by cells positive for classical HLA class I molecules including leukemic blasts. As shown by mAb inhibition studies, lysis of patient-derived phytohemagglutinin-activated T cell blasts by these early arising NK cells was specifically inhibited by engagement of CD94/NKG2A. KIR expression was restored with variable kinetics in the later post-transplantation phase (3–9 months). Interestingly, however, during this period, NK cells devoid of CD94/NKG2A were found to express at least one KIR specific for an HLA ligand present in the patient, suggesting functional silencing of NK cells arising in the later phases after transplantation by acquisition of specific KIRs. Taken together, these data challenge current broad view on putative antileukemic effect of alloreactive NK cells reconstituting from haploidentical donor CD34+ cells and suggest that optimal exploitation of NK alloreactivity for GvL requires the presence of NK cells matured in the context of the donor’s rather than the recipient’s HLA repertoire. Ultimately, these findings provide a rationale for emerging clinical evidence in favor of efficacy of NK-based immunotherapy with mature donor NK cells.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2005
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    In: New England Journal of Medicine, Massachusetts Medical Society, Vol. 361, No. 5 ( 2009-07-30), p. 478-488
    Type of Medium: Online Resource
    ISSN: 0028-4793 , 1533-4406
    RVK:
    Language: English
    Publisher: Massachusetts Medical Society
    Publication Date: 2009
    detail.hit.zdb_id: 1468837-2
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    In: Blood, American Society of Hematology, Vol. 112, No. 8 ( 2008-10-15), p. 3488-3499
    Abstract: In this study, we have characterized reconstitution of the natural killer (NK) cell repertoire after haploidentical CD34+ selected hematopoietic stem cell transplantation (HSCT) for high-risk hematologic malignancies. Analysis focused on alloreactive single-KIR+ NK cells, which reportedly are potent antileukemic effectors. One month after HSCT, CD56bright/CD56dim NK-cell subsets showed inverted ratio and phenotypic features. CD25 and CD117 down-regulation on CD56bright, and NKG2A and CD62L up-regulation on CD56dim, suggest sequential CD56bright-to-CD56dim NK-cell maturation in vivo. Consistently, the functional potential of these maturation intermediates against leukemic blasts was impaired. Mature receptor repertoire reconstitution took at least 3 months. Importantly, at this time point, supposedly alloreactive, single-KIR+ NK cells were not yet fully functional. Frequency of these cells was highly variable, independently from predicted NK alloreactivity, and below 1% of NK cells in 3 of 6 alloreactive patients studied. In line with these observations, no clinical benefit of predicted NK alloreactivity was observed in the total cohort of 56 patients. Our findings unravel the kinetics, and limits, of NK-cell differentiation from purified haploidentical hematopoietic stem cells in vivo, and suggest that NK-cell antileukemic potential could be best exploited by infusion of mature single-KIR+ NK cells selected from an alloreactive donor.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2008
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    In: Blood, American Society of Hematology, Vol. 114, No. 22 ( 2009-11-20), p. 46-46
    Abstract: Abstract 46 The broader application of haploidentical stem cell transplantation (haplo-HCT), is limited by the delayed immune reconstitution (IR) secondary to the procedures for GvHD prophylaxis. This ultimately results in a high-rate of infectious complications and non-relapse mortality. We dynamically analyzed immunoreconstitution (IR) in patients undergoing haplo-HCT for acute leukemias enrolled in two different phase I-II clinical trials aimed at improving IR. In the first trial (TK007), 28 patients (out of 50 enrolled) received suicide-gene transduced donor T cells at day +42 after a T-cell depleted graft, in the absence of post-transplant immunosuppression. In the second trial (TrRaMM), 40 patients received an unmanipulated graft and a rapamycin-based GvHD prophylaxis. T-cell immune reconstitution was more rapid in TrRaMM than in TK007 patients, with a threshold of CD3 cells 〉 100/μl reached at days +30 and +90, respectively. In both trials IR was mainly composed of Th1/Tc1 lymphocytes with an inverted CD4/CD8 ratio. While in TrRaMM patients we observed an early expansion of naïve and central memory T cells, producing high amounts of IL-2, in TK patients IR was mainly composed of activated effectors. Furthermore, in TrRaMM patients we detected high levels of CD4+CD25+CD127- T regulatory cells (up to 15% of circulating T lymphocytes) that persisted after rapamycin withdrawal, and was significantly superior to that observed in TK patients and in healthy controls. Interestingly, in contrast to the different kinetics of T-cell reconstitution, no differences were observed in time required to gain protective levels of CMV-specific T cells, as shown by ψIFN ELISPOT analysis. Protective frequencies of CMV-specific lymphocytes were observed 3 months after HCT in both groups, a time-point that in TrRaMM patients corresponds to the average time of rapamycin withdrawal. In both trials the number of circulating CMV-specific T cells was inversely correlated to the number and severity of subsequent CMV reactivations and days of antiviral therapy. GvHD was diagnosed in 16 TrRaMM patients (40%) and in 10 TK patients (35% of patients who received TK cells). Severity of GvHD was different in the two cohort of patients with 5 TrRaMM patients (12,5%) and only 2 TK patients (7%) with grade III-IV GvHD. Of interest, in the TrRaMM group CMV-specific immunity was significantly hampered by the immunosuppressive treatment required to treat GvHD. On the contrary, in the TK group, the administration of ganciclovir was able to activate the suicide machinery and control GvHD without impairing viral-specific T-cell immunocompetence. These results matched with the kinetics of CMV reactivations. We observed that while in TrRaMM patients 80% of viral reactivations occurred after the immunosuppressive therapy, in TK patients no significant differences could be assessed before and after therapy. IFN-ψ ELISPOT might thus be a relevant and predictive test to guide patient-specific clinical monitoring and antiviral treatment. Overall, these results show that early immune reconstitution can be promoted in haplo-HCT by different strategies associated with a wide range of alloreactive potential. The risks and benefits associated with alloreactivity should guide the therapeutic choice tuned on patient disease status and co-morbidities. Disclosures: Bordignon: Molmed Spa: Employment.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2009
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 190, No. 1_Supplement ( 2013-05-01), p. 170.41-170.41
    Abstract: Acute Myeloid Leukemia (AML) can be recognized and eliminated by the immune system, as demonstrated by the clinical efficacy of allogeneic hematopoietic stem cell transplantation. Still, immune-resistant variants of AML can outgrow upon the selective pressure of the transplanted immune system and determine clinical relapse, in a process called “leukemia immunoediting”, the biological bases of which remain largely unknown. To unravel novel mechanisms of immunoediting, we engrafted primary human AML in immunocompromised NOD/SCID γ-chainnull mice and modeled immune pressure by serial infusions of human T cells, either autologous or allogeneic to the leukemic cells. HLA-mismatched allogeneic T cells eradicated AML from 6/6 treated mice, whereas HLA-identical T cells granted only temporary control in 3/3 mice and autologous T cells were completely inefficacious in 3/3 mice. To fine-tune immune pressure from HLA-mismatched T cells, and thus model a phase of equilibrium before leukemia immune escape, we genetically modified allogeneic T cells to express the HSV-Tk suicide gene. The activation of the suicidal machinery abated circulating T cell counts in 3/3 mice, halted the ongoing antileukemic response and resulted in leukemia outgrowth. Gene expression profiling of the AML blasts purified from the mice upon escape from immune pressure demonstrated the selective and significant deregulation of genes involved in immune processes, including antigen processing and presentation.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    RVK:
    RVK:
    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2013
    detail.hit.zdb_id: 1475085-5
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    In: The Lancet Oncology, Elsevier BV, Vol. 10, No. 5 ( 2009-05), p. 489-500
    Type of Medium: Online Resource
    ISSN: 1470-2045
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2009
    detail.hit.zdb_id: 2049730-1
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    In: Blood, American Society of Hematology, Vol. 112, No. 11 ( 2008-11-16), p. 353-353
    Abstract: Background. Haploidentical family donors represent the ideal solution to offer to every patient with high risk leukemia the potential cure of hematopoietic stem cell transplantation. Extensive application of haploidentical transplantation (haplo-SCT) has been limited by high rate of late transplant related mortality (TRM) and relapse associated with the delayed immune reconstitution (IR) secondary to the procedures of profound T-cell depletion required for severe graft-vs-host-disease (GvHD) prevention. Methods. In a haplo-SCT phase I-II multicenter, open, non-randomized trial sponsored by MolMed SpA, we infused donor lymphocytes genetically engineered to express the suicide gene herpes simplex thymidine kinase (TK-DLI) to induce early IR, while selectively controlling GvHD. We enrolled 54 patients (pts) -median age 51- with high-risk hematologic malignancies. Thirty-two patients were in remission at transplantation. Results. After myeloablative conditioning regimen, 50 pts received a median 11×10^6/ kg CD34+ and 1.1×10^4/kg CD3+ after Clinimacs CD34+ selection. Median time to engraftment of neutrophils & gt; 1.0 ×10^9/L and platelets & gt; 50 ×10^9/L was 14 days. TK cells could always be prepared in the appropriate timeframe, and no drop out secondary to inadequate cell manipulation occurred. Twenty-eight pts received TK-DLI at a dose of CD3+ cells of 0.9–40 ×10^6/kg: 22 pts obtained prompt IR with CD3+ & gt;100/mcl at day +75 (median) from haplo-SCT and day +23 from TK-DLI. Eleven pts developed GvHD (10 acute GvHD grade I-IV and 1 chronic GvHD) that was always abrogated by the suicide gene induction; no progression from acute GvHD to chronic GvHD and no GvHD-related death or long-term complication occurred. No acute or chronic adverse event related to the gene transfer procedure was observed during extended follow-up. With a median follow-up of 178 days (range 2–1821), the 3-year TRM in intention to-treat (ITT) analysis was 40% with last mortality event at d+166. Significantly, the cumulative infectious mortality was 10% in TK-treated immune-reconstituted patients. Immune reconstitution obtained with TK-cells infusion correlated with rapid development of a wide T-cell repertoire and detection of high frequencies of T-cells specific for opportunistic pathogens. Initially, TK-cells represented the predominant T cell component in reconstituting patients and showed a effector memory phenotype, an oligoclonal repertoire and a persistent ganciclovir sensitivity. At later times, untransduced cells progressively expanded and became the prevalent circulating lymphocyte population. This reconstitution kinetic was observed only in patients with TK-cell engraftment, suggesting a critical homeostatic contribution of TK-cells early after transplant. One year after TK cells infusion the repertoire and distribution of T cell subsets completely normalized. In ITT, the median leukemia-free survival (LFS) for patients transplanted with advanced chemoresistant disease was at d+169, while patients in remission at the time of transplantation showed an overall survival in ITT of 51% at 1 year. Conclusions. This multicenter trial confirm the safety and potential benefit in improving survival of the gene transfer technology integrated with a standard therapeutic procedure such as allogeneic SCT. The conditional benefit for patients treated with TK cells was remarkable as indicated by a complete abrogation of late infectious mortality provided by the fast and effective immune reconstitution. In the future, this technology based on genetic engineering of activated donor lymphocytes with higher allo-reactive potentialwill potentially impact also the transplant outcome of patients with refractory disease.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2008
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    In: Blood, American Society of Hematology, Vol. 106, No. 11 ( 2005-11-16), p. 3096-3096
    Abstract: Suicide gene therapy (SGT) is a powerful approach to exploit anti-host reactivity following allogeneic hemopoietic cell transplantation (allo-HCT) for a full graft-versus-leukemia (GvL) effect, while controlling graft-versus-host disease (GvHD). This is accomplished through genetic modification of donor lymphocytes with a suicide gene. The herpes simplex thymidine kinase (TK) suicide gene converts at a cellular level the pro-drug ganciclovir (GCV) into tri-phosphate toxic derivatives, thence conferring selective sensitivity. Clinical studies as well as animal models have substantiated the concept that a time-wise GCV administration is able to actually separate the therapeutic GvL effect from life-threatening GvHD. Genetic modification of lymphocytes with TK is currently pursued through retroviral vectors (RV). In vitro RV genetic modification requires proliferation, which is easily accomplished by polyclonal stimulation. Polyclonal stimulation with anti-CD3 antibodies (aCD3) has been show to reduce anti-host reactivity of gene-modified lymphocytes. This possibly limits the impact of the suicide gene strategy in allo-HCT. In this study we tackled the rules governing anti-host reactivity of TK+ human lymphocytes. We found that TK+ lymphocytes generated with aCD3 are mainly CD45RA−CCR7− effector memory (EM) cells (84,6±6,6%). Upon re-stimulation they produce interferon-γ, perforin B and granzyme A, but fail to up-regulate CD40L. EM TK+ lymphocytes have a mixed phenotype in regard to CD28/CD27 co-expression and displayed a limited ability to engraft and cause GvHD in a xenogeneic model using conditioned NOD/scid mice (take: 11%). In sharp contrast, TK+ lymphocytes generated with novel protocols taking advantage of anti-CD3 and anti-CD28 antibodies conjugated to para-magnetic cell-sized beads are enriched for CD45RA−CCR7+ central memory (CM) cells (65,3±6,2%) that are able to produce IL-2 and to strongly up-regulate CD40L. CM TK+ lymphocytes are homogenously CD28+CD27+ (91,1,3±2,5%). When infused in conditioned NOD/scid mice CM TK+ lymphocytes persistently engrafted and caused lethal GvHD in a significant fraction of mice (take: 55%, P=0,0017 vs EM TK+ cells). GCV administration to diseased animals resulted in the elimination of TK+ cells in blood and in target organs. Treated animals were rescued with survival up to 120 days (P=0,009 vs saline-treated mice). These results demonstrate that CM TK+ lymphocytes retain significant anti-host reactivity and provide a clue to their in vitro generation. CM TK+ lymphocytes are promising candidates for safe and effective allo-HCT for the cure of hematological malignancies.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2005
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    In: Blood, American Society of Hematology, Vol. 128, No. 22 ( 2016-12-02), p. 4581-4581
    Abstract: Background: Post transplant immune reconstitution plays a major role in determining the outcome of allogeneic hematopoietic stem cell transplantation (allo-HSCT), and is currently monitored with different techniques in different Centers, with the aim of identifying clinically relevant immunological biomarkers. However, it is unclear which and how many of these immunological tests are currently performed on a routine basis, and which ones have the potential to predict patient outcome, and possibly guide patient care after allo-HSCT. Methods: The EBMT Cellular Therapy & Immunobiology Working Party (CTIWP) conducted a survey to identify current policies to monitor immune reconstitution in patients undergoing allo-HSCT and possibly reach a general consensus. This study followed the EBMT study guidelines. All EBMT Centers were invited to participate. Each participating Center received a questionnaire on the availability of specific immunomonitoring assays, specifying the use in clinical practice and/or within investigational trials. Assays were based on relatively simple and readily available parameters such as absolute lymphocyte counts (ALC) to more complex cellular and molecular tests. Moreover, the Centers were asked to define the transplant platform (HLA-identical sibling, matched unrelated donor, haploidentical and/or cord blood) on which each test is generally performed. Results: Policies for post-transplant immunomonitoring have been reported by 35 participating EBMT Centers active in 14 Countries and performing allo-HSCT from HLA identical related (35 centers), matched unrelated (33), haploidentical (34), unrelated cord blood (27). Complete blood counts and immunoglobulins are routinely tested for patients' care by all centers. Relative proportions of T cell subsets are currently tested by flow-cytometry as "standard of care" or "investigational" by 82% and 17% of centers respectively. B cell and NK cell counts are quantified routinely by 46% and 23% of Centers, and investigationally by 40% of Centers. The availability of molecular tests (STR, qPCR, Fish) to measure post-transplant engraftment are reported by all Centers, except two, as a standard of care measure. T cell receptor-expressing circles (TRECs) and/or K-deleting recombination excision circles (KRECs) are quantified within selected clinical trials by 37% of Centers. Interestingly, 60% of Centers evaluate, mostly as an investigational measure, antigen specific T cell responses by: proliferation assays (49%), interferon-gamma enzyme-linked immunospot-Elispot (49%), intracellular cytokine staining (46%) and tetramer/dextramer staining (37%). Most of these Centers test responses to Cytomegalovirus and Epstein Barr Virus, and 5 Centers use at least one of these assays on a routine basis. About half of the participating Centers (43%) commonly test antigen-specific antibodies, mainly as responses to vaccines, and not routinely. T-cell receptors (TCR) and B-cell receptors (BCR) repertoires are measured by spectratyping in 14 out of 35 Centers (4 as clinical practice and 10 in selected trials), or, in selected trials, by next generation sequencing (in 11 out of 35 the participating Centers). Conclusions: Results of this survey indicate that country- and center expertise are associated with heterogeneous and distinct protocols, and underline the clinical need to harmonize methods and to provide practical recommendations for monitoring post-transplant immune reconstitution, both for routine purposes and investigational studies. Adequate reporting and connection between individual Centers exploiting these data will foster collaborative and comparative research studies, with the ultimate goals of improving patient care and refining our understanding of the immunological correlates to clinical outcome. Acknowledgments: R. Ram, M. A. Diaz, G. McQuaker, D. Russo, E. Faber, P. Chiusolo, C. Rössig, S. M. Martin, A. Anagnostopoulos, M. Stelljes, K. Orchard, P. Jindra, A. Sampol, K. Patrick, M. A. Bekadja, J. Gayoso, A. Olivieri, J. Passweg, E. Jost, H Labussiere-Wallet, Y Koc, A. Lange, I. Garcia Cadenas, N. Kröger, A. Biondi, N. Milpied, D. Olive, E. Lanino, G. Stuhler, J.H. Dalle, J.R. Cabrera Marín, F. Ciceri, D. Uckan-Cetinkaya, R. Parody Porras, G. Kriván. Disclosures Ciceri: MolMed SpA: Consultancy. Bonini:TxCell: Membership on an entity's Board of Directors or advisory committees; Molmed SpA: Consultancy.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2016
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    In: Blood, American Society of Hematology, Vol. 118, No. 21 ( 2011-11-18), p. 329-329
    Abstract: Abstract 329 BACKGROUND: The curative potential of Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) for Acute Myeloid Leukemia (AML) is mostly based on the ability of donor lymphocytes to actively control the outgrowth of host residual malignant cells. We demonstrated in the specific context of HLA-haploidentical HSCT that this equilibrium is frequently broken by de novo genomic mutations, causing loss of the mismatched HLA haplotype in leukemic cells, in turn leading to immune evasion and clinical disease relapse (Vago et al., N Engl J Med, 2009). This finding led us to hypothesize that different de novo genomic or transcriptional alterations may be at the base of other cases of post-transplantation AML relapse, prompting us to verify this hypothesis by high-throughput techniques in the present study. METHODS: Paired samples of AML harvested at diagnosis and at relapse after non T cell-depleted allogeneic HSCT (either from HLA-identical, matched unrelated or haploidentical donors) were FACS-purified and analyzed by whole-genome Single Nucleotide Polymorphysm (SNP) profiling (by the Illumina Human660W-Quad BeadChip) and gene expression analysis (by the Illumina HumanHT-12 v3.0 Expression Bead chip). The presence and allelic burden of the Internal Tandem Duplication (ITD) in the FLT3 gene was validated by a locus-specific PCR followed by capillary electrophoresis. RESULTS: In 6 out of the 11 patients without genomic loss of HLA analyzed to date (54.5%), SNP profiling demonstrated the acquisition of de novo genomic alterations at post-transplantation relapse, preferentially occurring in well-characterized leukemia-associated genes (WT1, FLT3). Uniparental Disomy (UPD) was the most common alteration (45.5% of cases at diagnosis and 63.6% at relapse), frequently involving chromosome 13 in regions encompassing the FLT3 gene. Interestingly, in 5/11 patients (45.4%) we observed clonal evolution of leukemia at relapse from an oligoclonal population at diagnosis, with preferential expansion of the clones carrying genomic alterations. A total of 5 patients showed at relapse either de novo appearance of chromosome 13 UPD or the enrichment in a preexisting clone carrying the alteration: interestingly 4 out of these 5 patients gained in the process a substantial increase in the allelic burden of the ITD form of the FLT3 gene, which tightly correlates with aggressive behavior of leukemia. Gene expression profiling of paired diagnosis-relapse samples from 7 patients revealed deregulation by at least three-fold in an average of 3% (0.8–5.1%) genes at post-transplantation relapse as compared to diagnosis. An unsupervised Gene Ontology analysis of these genes evidenced a significant enrichment in immune-related processes (p 〈 10−14) in 3 of these patients, who displayed the earliest relapse onset after transplantation (median time 30 days, range 29–54). Such enrichment was not observed in the remaining 4 patients with later relapse onset (median time 152 days, range 98–299), suggesting a rapid imprint of the donor immune cells contained in the graft on the leukemia transcriptional profile. A relevant observation was made in a patient who relapsed early after haploidentical HSCT without any documented genomic alteration in the HLA locus. In this patient, we could demonstrate at the time of post-transplantation relapse the specific transcriptional downregulation of the HLA class II antigen presentation pathway, whereas class I expression was preserved. Moreover, HLA class II expression was completely recovered in the absence of T cell immune pressure when the leukemic blasts harvested at relapse were transferred in immunodeficient NOD/SCID mice, suggesting plasticity of this mechanism of immune evasion. CONCLUSIONS: Our data demonstrate that both genomic and transcriptional alterations occur frequently at leukemia relapse after allogeneic HSCT. The frequent selection of leukemic clones displaying specific unfavorable mutations (such as FLT3-ITD) from initially mixed populations grants a biological rationale for the post-transplantation use of targeted inhibitors to block the outgrowth of the more aggressive subsets. Moreover, the observation that not only genomic, but also transcriptional HLA loss can be at the basis of relapse after haploidentical HSCT warrants further optimization of current protocols of post-transplantation monitoring and treatment of disease relapse. Disclosures: Bonini: MolMed SpA: Consultancy.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2011
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages