Molecular monitoring of minimal residual disease in two patients with MLL-rearranged acute myeloid leukemia and haploidentical transplantation after relapse
- Thomas Burmeister1Email author,
- Mara Molkentin1,
- Claus Meyer2,
- Nils Lachmann3,
- Stefan Schwartz1,
- Birte Friedrichs1,
- Jörg Beyer4,
- Igor Wolfgang Blau1,
- Gunnar Lohm5,
- Carola Tietze-Bürger6,
- Rolf Marschalek2, 7 and
- Lutz Uharek6
© Burmeister et al.; licensee BioMed Central Ltd. 2012
Received: 16 March 2012
Accepted: 18 April 2012
Published: 18 April 2012
This report describes the clinical courses of two acute myeloid leukemia patients. Both had MLL translocations, the first a t(10;11)(p11.2;q23) with MLL-AF10 and the second a t(11;19)(q23;p13.1) with MLL-ELL fusion. They achieved a clinical remission under conventional chemotherapy but relapsed shortly after end of therapy. Both had a history of invasive mycoses (one had possible pulmonary mycosis, one systemic candidiasis). Because no HLA-identical donor was available, a haploidentical transplantation was performed in both cases. Using a specially designed PCR method for the assessment of minimal residual disease (MRD), based on the quantitative detection of the individual chromosomal breakpoint in the MLL gene, both patients achieved complete and persistent molecular remission after transplantation. The immune reconstitution after transplantation is described in terms of total CD3+/CD4+, CD3+/CD8+, CD19+, and CD16+/CD56+ cell numbers over time. The KIR and HLA genotypes of donors and recipients are reported and the possibility of a KIR-mediated alloreactivity is discussed. This report illustrates that haploidentical transplantation may offer a chance of cure without chronic graft-versus-host disease in situations where no suitable HLA-identical donor is available even in a high-risk setting and shows the value of MRD monitoring in the pre- and posttransplant setting.
KeywordsMinimal residual disease Haploidentical stem cell transplantation MLL KIR Acute myeloid leukemia
Acute myeloid leukemia (AML) is a molecularly heterogeneous disease. Around 5–10% of affected patients show MLL translocations and an additional 8% have a MLL partial internal duplication. While MLL aberrations have historically and generally been associated with an adverse prognosis, this view has become more differentiated during recent years and at least for some rarer MLL aberrations this verdict appears to be unfounded . The 5 most common MLL aberrations in adult AML are t(9;11)/MLL-AF9, t(6;11)/MLL-AF6, t(11;19)/MLL-ELL, t(11;19)/MLL-ENL, and t(10;11)/MLL-AF10, together accounting for around 80% of cases [2, 3]. The general recommendation for younger and medically fit AML patients is allogeneic transplantation. The only exception are the core-binding factor leukemias with either CBFA2-ETO or CBFB-MYH11, and acute promyelocytic leukemia with PML-RARA, if no additional high-risk features (e.g. FLT3-ITD) are present. Around 15–30% of patients referred for transplantation have a suitable HLA-identical sibling donor. Large donor registries can be accessed for those patients without a HLA-identical sibling donor, but the likelihood of finding a suitable donor depends strongly on the ethnic background of the patient . Currently it is possible to identify a suitable HLA-identical donor in around 70% of patients of European ancestry . Different options exist for those patients without a fully (10/10) HLA antigen-matched donor. Clinical trials with donors showing only a 9/10, 8/10 or even 7/10 HLA match have shown a significantly higher transplant-related mortality, mainly due to the higher incidence of severe graft-versus-host disease (GvHD) [6–8]. The Perugia group of Martelli and coworkers first introduced the concept of transplanting “megadoses” of highly purified CD34+ cells of a HLA-haploidentical donor in the clinical setting to overcome the HLA barrier and prevent graft failure [9, 10]. To achieve an alloreactive antileukemic effect in the absence of alloreactive T-cells, donor-derived natural killer (NK) cells were infused .
This report describes the clinical courses of two patients with MLL-rearranged AML and particular high risk features (early relapse, invasive mycoses) with particular emphasis on the MRD monitoring method which was based on the quantitative detection of the individual chromosomal breakpoints in the MLL gene. Both patients had no suitable HLA-identical donor and thus haploidentical transplantations were performed. The immune reconstitution after transplantation in terms of B-cells, CD4+ and CD8+ T-cells and NK cells is described.
Features at presentation
A 33-year-old male patient was diagnosed with acute myeloid leukemia. The first clinical symptoms were dyspnoea on exertion, a generalized maculopapular rash, gingival hyperplasia, and general weakness. The blood count at diagnosis revealed 52/nl leukocytes (79% blasts) a hemoglobin of 11.1 g/dl (hematocrit 0.33), and platelets of 110/nl. The LDH was 1306 U/l (normal < 248 U/l), creatinine 1.27 mg/dl, C-reactive protein 16.1 mg/dl (normal <0.5 mg/dl). Bone marrow cytology revealed an increased overall cellularity and an 80% infiltration by medium-sized blasts with basophilic cytoplasm, partial cytoplasmic vacuolisation, prominent nucleoli, and positive esterase staining, compatible with acute myeloid leukemia of the FAB M5a subtype (Figure 1). Flow cytometric analysis of the bone marrow revealed an expression of myeloid antigens and HLA-DR with aberrant CD4 and CD56 expression. Cytogenetic analysis revealed a 46,XY,t(10;11)(p11.2;q23) karyotype and molecular analysis by RT-PCR an MLL-AF10 fusion transcript.
The patient was randomized into arm C of the German AML2003 study after informed consent. The study protocol comprises two cycles DA (100 mg/m2 = 200 mg cytarabine continuously, d1-7 + 60 mg/m2 = 120 mg daunorubicine, d3-5) followed by 3 cycles post-remission therapy (MAC-MAMAC-MAC) with MAC = 2 × 1 g/m2 cytarabine d1-6 + 10 mg/m2 mitoxantrone d4-6 and MAMAC = 2 × 1 g/m2 cytarabine d1-5 + 100 mg/m2 amsacrine d1-5. An allogeneic transplant is recommended after completion of the first two cycles, if a donor is available. However, no HLA-identical sibling or unrelated donor could be identified in this case.
The inital clinical course was complicated by severe adverse events. During the first days of DA induction the patient suffered from acute dyspnea which led to his admission to the intensive care unit where he first received CPAP (Continuous Positive Airway Pressure) and then mechanical ventilation. A thoracic CT scan showed bilateral pleural effusions and atypical infiltrates. During these first days right-sided hemiplegia and desorientation developed. A cranial CT scan showed a left frontal and right pareto-occipital parenchymal bleeding. The renal function deteriorated and hemodialysis had to be performed. The clinical situation improved under broad-spectrum antibiotic treatment, the mechanical ventilation and hemodialysis could be discontinued and after 24 days on the ICU the patient was readmitted to the ward. The patient made a full recovery under intensive physical therapy with no residual neuro-psychiatric deficits. A bone marrow biopsy on day 15 after start of therapy showed a partial remission with around 10 to 20% blasts, and a second bone marrow biopsy on day 27, i.e. after leukocyte and platelet recovery, showed cytologically a suspicious residual blast population; however, flow cytometry did not confirm a significant blast population. The second induction cycle started on day 34 and had less adverse events. However, the patient developed febrile neutropenia and a methicillin-resistant Staphylococcus aureus (MRSA) was isolated from a blood culture. Despite receiving antibiotic treatment according to the resistogram, the patient developed pneumonic infiltrates and increasing C-reactive protein levels which only improved after a combination of voriconazole and liposomal amphotericin was added to the antibiotic regimen. After leukocyte recovery all symptoms rapidly resolved and the patient could be discharged with a prophylactic posaconazole medication. The therapy was continued with 3 consolidation cycles (MAC-MAMAC-MAC). Stem cells apheresis was performed after the second consolidation cycle. Complications during consolidation included reactivation of the pulmonary mycosis and a marked cervical lymphadenitis. Bone marrow cytology after each cycle showed a complete remission.
Assessment of minimal residual disease (MRD)
Relapse and salvage therapy
Three and a half months after end of the therapy the patient presented with an inguinal swelling. A biopsy and a bone marrow investigation was undertaken. The inguinal biopsy revealed an extramedullary AML relapse. While bone marrow cytology appeared normal, MRD investigation showed MRD positivity (Figure 2). A second bone marrow investigation two weeks later confirmed the relapse. In addition, patchy skin infiltrates appeared. The patient was treated according to the Mito-FlAG scheme (2×15 mg/m2 fludarabine; 2×1000 mg/m2 cytarabine d1-5; 7 mg/m2 mitoxantrone d1,3,5). The treatment was relatively well-tolerated and besides a venous catheter-associated S. epidermidis bacteriaemia, no major complications occurred. After therapy the patient achieved complete cytomorphologic remission, the extramedullary manifestations had disappeared and no MRD was detectable in the bone marrow.
Long-term follow-up and immune reconstituion
Features at presentation (relapse)
Salvage treatment and disseminated candidiasis
The patient was treated according to a modified FlAmsa protocol (30 mg/m2 fludarabine d1-4, 100 mg/m2 amsacrine d1-4, 2000 mg/m2 cytarabine). During the subsequent aplasia she developed an increase in C-reactive protein to around 30 mg/l (normal < 0.5 mg/l) despite broad-spectrum antibiotic treatment. A thoracic CT scan showed small bilateral pulmonary and hepatic lesions suggestive of atypical or fungal pneumonia. An MR scan of the abdomen showed hepatomegaly (22 cm craniocaudal diameter) with multiple lesions in liver, spleen and kidneys, measuring up to 8 mm in diameter. At the same time, an elevated Candida antigen level was detected in the serum. The patient was initially treated with liposomal amphotericin B and later with voriconazole. A bronchoalveolar lavage revealed 100–1.000 colony-forming units/ml Candida dubliniensis and a liver biopsy showed neither leukemic infiltrates nor fungi. Candida dubliniensis was later also isolated from a stool specimen. Systemic candidosis was diagnosed, the antimycotic treatment was changed to caspofungin and after a further increase in Candida antigen titer to micafungin with liposomal amphotericin B. The manifestation in lungs, liver, spleen and kidneys regressed and the C-reactive protein and the Candida antigen titer normalized after leukocytic regeneration. Liposomal amphotericin was discontinued 11 days before transplantation and micafungin was continued until day +31 after transplantation after which it was replaced by posaconazole. The candidiasis delayed the scheduled transplantation by about 4 weeks.
Immunogenetic characteristics (HLA and KIR genotypes)
B*1801, B*4101, Cw*0102, Cw*1701, DRB1*0301, DRB1*1301, DQB1*0201, DQB1*0603
B*1801, B*4403, Cw*0102, Cw*1601, DRB1*0301, DRB1*0701, DQB1*0201, DQB1*0202
2DL1+, 2DL2+, 2DL3-, 2DL4+, 2DL5+, 2DP1+, 2DS1 +, 2DS2+, 2DS3+, 2DS4-, 2DS5-, 3DL1+, 3DL2+, 3DL3+, 3DP1+, 3DS1+ (2DS4 could not be excluded).
2DL1+, 2DL2+, 2DL3+, 2DL4+, 2DL5-, 2DP1+, 2DS1-, 2DS2+, 2DS3-, 2DS4+, 2DS5-, 3DL1+, 3DL2+, 3DL3+, 3DP1+, 3DS1+
B*4403, B*5701, Cw*0401, Cw*0602, DRB1*0402, DRB1*0701, DQB1*0201, DQB1*0302
Cw*0501, Cw*0602, DRB1*0401, DRB1*0701, DQB1*0201, DQB1*0301
2DL1+, 2DL2-, 2DL3+, 2DL4+, 2DL5+, 2DP1+, 2DS1+, 2DS2-, 2DS3-, 2DS4+, 2DS5+, 3DL1+, 3DL2+, 3DL3+, 3DP1+, 3DS1+
2DL1+, 2DL2-, 2DL3+, 2DL4+, 2DL5+, 2DP1+, 2DS1+, 2DS2-, 2DS3-, 2DS4+, 2DS5+, 3DL1+, 3DL2+, 3DL3+, 3DP1+, 3DS1+
CD34 + cells transplant characteristics
Total WBC (106)
CD34+count (106), total and per kg
CD3+count (103), total and per kg
NK cell doses
Total WBC (106)
CD56+count (106), total and per kg
CD3+count (103), total and per kg
Immune reconstitution and MRD after transplantation
The MRD level was continuously negative in all investigations after transplantation during the follow-up period of more than one year (Figure 5). Immune reconstitution occurred relatively fast, and T helper cells first reached a level of >200/nl on day +36. A peak in CD8+ cells was observed on day +49 followed by a peak in CD8+ cells on day +58.
Haploidentical transplantation and the possible role of KIR mismatches
The difficulties in finding a suitable HLA-identical donor for every patient in need for it led to the idea of considering the “always present but overlooked”  haploidentical relatives as potential donors. The patient’s parents and children are always HLA-haploidentical and the probability of a patient’s sibling being HLA-haploidentical is 50% in contrast to 25% probability for full HLA identity. Thus in practical reality the probability of finding a HLA-haploidentical relative is nearly 100%.
Two major problems have to be overcome in haploidentical transplantation: the first is graft rejection and the second is severe graft-versus-host disease. The group of Martelli et al. first demonstrated clinically that this is possible by using large amounts (“megadoses”, i.e. > 107/kg) of highly purified CD34+ hematopoietic stem cells. These purified stem cells are largely devoid of T-cells which are responsible for the graft-versus-host effect.
To achieve some kind of alloreactivity against residual recipient’s blood cells, donor-derived natural killer (NK) cells have been infused. The basis of this NK alloreactivity is not fully understood. NK cells are able to attack other cells that show downregulation of HLA class I molecules on their surface which is often the case in virus-infected cells or tumor cells. However, HLA class I downregulation is neither necessary nor sufficient for NK cell activation as is illustrated by the fact that normal cells or tissues lacking HLA class I expression (e.g., erythrocytes) or showing low HLA class I expression (e.g., neural cells) are not attacked by autologous NK cells. Cytotoxic NK cell activity is believed to be mainly determined by the presence of inhibitory or activating receptors on the NK cell surface. Two major types of inhibitory receptors have been identified: killer cell immunoglobulin-like (KIR) receptors and the CD94/NKG2A heterodimer, a C-type lectin, which interacts with the non-classical class Ib HLA-E molecule (reviewed in ). While the ligands for many KIR receptors are unknown, the inhibitory receptors KIR2DL1, KIR2DL2 and KIR3DL1 bind epitopes of HLA-C (’HLA-C2, -C1’ groups) and HLA-A and HLA-B molecules with ’Bw4” motif, respectively . Upon encountering self-class HLA antigen, NK cell–mediated lysis and cytokine release are inhibited.
While HLA genes are located in the MHC complex on chromosome 6p21.3, KIR genes are clustered in the leukocyte receptor complex (LRC) on chromosome 19q13.4. Thus they segregate independently in human pedigrees. The LRC is highly polymorphic and contains seven to 15 KIR gene loci dispersed within a region of 65 to 200 kb . It is not yet fully understood how NK cells are “educated” not to attack other autologous cells lacking inhibitory HLA ligands for their KIR receptors [18, 19]. Various models have been proposed to explain the experimentally observed alloreactivity of NK cells. The “licensing model” predicts that NK cells that do not receive a signal through an inhibitory receptor become hyporesponsive instead of alloreactive. The “Ruggieri model” assumes that NK cells with inhibitory KIR receptors for ligands absent on both donor and recipient are nonalloreactive. The effect of NK cell alloreactivity in the setting of a fully HLA-matched transplantation has been controversially discussed (synopsis in ). Some groups have found a benefit in overall survival in case of a KIR-HLA class I mismatch , but others could not confirm this and found no effect  or even a worse outcome . In haploidentical transplantation the Perugia group has published evidence that NK cells with a mismatch between donor KIR and recipient's HLA molecules in graft-versus-host direction positively correlate with outcome at least in patients with myeloid leukemias [10, 11].
Both our patients and their donors showed inhibitory and activating KIR genes corresponding to KIR haplotype group B. KIR ligands and mismatches were calculated using the EMBL IPD-KIR database release 2.4.0 . Both donors were KIR3DL1-positive but only the second patient had the corresponding inhibitory receptor Bw4 (B44 and B57 with Bw4). The donor of patient 1 expressed KIR2DL2, 2DL3, 2DS2, 2DL1 and 2DS2, all of which are ligands for Cw1 und Cw17, which were expressed by patient 1. The first patient showed mismatches in both directions, a mismatch in GvH direction (donor KIR3DL1-based) and a mismatch in HvG direction (recipient KIR2DL1-based). The second patient showed neither a mismatch in GvH nor HvG direction. Since no functional tests were performed it was not possible to assess any NK cell-based alloreactivity in both cases.
Minimal residual disease before and after transplantation
Due to the extraordinary genetic heterogeneity of AML, it is difficult to set up general recommendations for molecular monitoring of residual disease (recently reviewed by [24–26]). Astonishingly few studies have addressed the issue of MRD monitoring before and after allogeneic transplantation in AML. Although the same MRD levels may have a different prognostic impact in “good risk” and “bad risk” AML, there is little doubt that the level of molecular remission is in principle of critical importance for the probability of long-term remission and the risk of relapse. The issue how often and when to assess MRD in AML is still controversial, but attempts have been made to provide general recommendations for MRD monitoring . Basically two different methods have been used for MRD assessment, polymerase chain reaction (PCR) and flow cytometry. The main advantage of flow cytometry is the speed of getting results; however, disadvantages of the method are the lack and principal difficulties in standardization. The theoretical maximum achievable sensitivity is higher for flow cytometry than PCR, but in reality it is often significantly lower. To obtain a higher sensitivity, multiparameter flow has to be used, but this again makes the procedure more complicated and investigator-dependent. PCR is based on the quantitative detection of clonal markers which are often, but not necessarily, also disease markers, such as leukemogenic fusion genes. In lymphoid neoplasms the clonally rearranged immune genes of the malignant clone can often be used as an MRD target. They are no disease but surrogate markers and may sometimes get lost during the course of disease due to further immune gene rearrangements. Detection of MRD by PCR can be based on RNA or DNA targets. RNA targets, such as chimeric transcripts originating from leukemogenic fusion genes, can often be assessed more easily, but MRD detection based on such RNA molecules has the disadvantage that no absolute quantification is possible. Instead the quantification is calculated relative to a “housekeeping gene” or “control gene” which is supposed to be stably expressed; of course this can only be an approximation. Besides that, RNA is relatively unstable and degrades easily if not stored at low temperatures. In contrast, DNA is remarkably stable, usually over several days at room temperature. PCR methods based on the quantification of DNA targets allow a precise absolute quantification of the target. It is not trivial to find such a clonal PCR target in every case of AML. However, in acute leukemia with MLL translocation it is possible and feasible to use the chromosomal breakpoint in the MLL gene as a molecular marker for PCR . The resulting PCR usually has a very high sensitivity and stability. The MLL breakpoint can relatively easily and elegantly be identified using a generic inverse PCR method .
Sixteen AML patients at our institution received a haploidentical stem cell transplant in the time period between 2004 and 2011, mostly because no suitable HLA-identical donor was available, but in a few cases also because of relapse after HLA-identical stem cell transplantation. Fifteen out of the sixteen patients were transplanted with active disease/relapse at transplantation. The overall survival was 24% with a median follow-up of 3.7 years (detailed data soon to be published). Several factors may have contributed to the favourable outcome despite several risk factors in our two patients. First, both were relatively young and had virtually no comorbidities. Second, in spite of early relapses, the leukemias were still chemotherapy-sensitive and responded relatively well to salvage therapy. Third, the MRD niveau before transplantation was not very high. A high pre-HCT MRD level has been associated with an increased risk of relapse after myeloablative HCT for AML . Last but not least the regular MRD assessments were certainly helpful to guide therapeutical decisions during the course of disease.
In short summary, the two cases presented here illustrate the value of regular MRD monitoring in the pre- and post-transplant setting for guiding clinical decisions. They show exemplarily the immune reconstitution after haploidentical transplantation and illustrate that under certain circumstances haploidentical transplantation may be an option even for patients with a history of invasive fungal infections.
Written informed consent was obtained from the patients for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
TB was supported by the Deutsche José Carreras Leukämiestiftung e.V. We thank Michael H Notter, Olaf Hopfer, Johannes Lakner and Klaus Axel Nogai for their contributions in the treatment of the patients and Constanze Schönemann for supervising the HLA typing. The authors thank the laboratory technicians of the flow cytometry and bone marrow morphology lab and all involved nursing staff for their professional and skilful work.
- Balgobind BV, Raimondi SC, Harbott J, Zimmermann M, Alonzo TA, Auvrignon A, Beverloo HB, Chang M, Creutzig U, Dworzak MN, Forestier E, Gibson B, Hasle H, Harrison CJ, Heerema NA, Kaspers GJ, Leszl A, Litvinko N, Nigro LL, Morimoto A, Perot C, Pieters R, Reinhardt D, Rubnitz JE, Smith FO, Stary J, Stasevich I, Strehl S, Taga T, Tomizawa D, Webb D, Zemanova Z, Zwaan CM, van den Heuvel-Eibrink MM: Novel prognostic subgroups in childhood 11q23/MLL-rearranged acute myeloid leukemia: results of an international retrospective study. Blood 2009, 114: 2489–2496.PubMed CentralPubMedView Article
- Meyer C, Kowarz E, Hofmann J, Renneville A, Zuna J, Trka J, Ben Abdelali R, Macintyre E, De Braekeleer E, De Braekeleer M, Delabesse E, de Oliveira MP, Cave H, Clappier E, van Dongen JJ, Balgobind BV, van den Heuvel-Eibrink MM, Beverloo HB, Panzer-Grumayer R, Teigler-Schlegel A, Harbott J, Kjeldsen E, Schnittger S, Koehl U, Gruhn B, Heidenreich O, Chan LC, Yip SF, Krzywinski M, Eckert C, Moricke A, Schrappe M, Alonso CN, Schafer BW, Krauter J, Lee DA, Zur Stadt U, Te Kronnie G, Sutton R, Izraeli S, Trakhtenbrot L, Lo Nigro L, Tsaur G, Fechina L, Szczepanski T, Strehl S, Ilencikova D, Molkentin M, Burmeister T, Dingermann T, Klingebiel T, Marschalek R: New insights to the MLL recombinome of acute leukemias. Leukemia 2009, 23: 1490–1499.PubMedView Article
- Shih LY, Liang DC, Fu JF, Wu JH, Wang PN, Lin TL, Dunn P, Kuo MC, Tang TC, Lin TH, Lai CL: Characterization of fusion partner genes in 114 patients with de novo acute myeloid leukemia and MLL rearrangement. Leukemia 2006, 20: 218–223.PubMedView Article
- Joshua TV, Rizzo JD, Zhang MJ, Hari PN, Kurian S, Pasquini M, Majhail NS, Lee SJ, Horowitz MM: Access to hematopoietic stem cell transplantation: effect of race and sex. Cancer 2010, 116: 3469–3476.PubMed CentralPubMedView Article
- Tiercy JM, Nicoloso G, Passweg J, Schanz U, Seger R, Chalandon Y, Heim D, Gungor T, Schneider P, Schwabe R, Gratwohl A: The probability of identifying a 10/10 HLA allele-matched unrelated donor is highly predictable. Bone Marrow Transplant 2007, 40: 515–522.PubMedView Article
- Spitzer TR: Haploidentical stem cell transplantation: the always present but overlooked donor. Hematology Am Soc Hematol Educ Program 2005, 2005: 390–395.View Article
- Reisner Y, Hagin D, Martelli MF: Haploidentical hematopoietic transplantation: current status and future perspectives. Blood 2011, 118: 6006–6017.PubMedView Article
- Huang XJ: Current status of haploidentical stem cell transplantation for leukemia. J Hematol Oncol 2008, 1: 27.PubMed CentralPubMedView Article
- Aversa F, Martelli MM, Reisner Y: Use of stem cells from mismatched related donors. Curr Opin Hematol 1997, 4: 419–422.PubMedView Article
- Aversa F, Tabilio A, Velardi A, Cunningham I, Terenzi A, Falzetti F, Ruggeri L, Barbabietola G, Aristei C, Latini P, Reisner Y, Martelli MF: Treatment of high-risk acute leukemia with T-cell-depleted stem cells from related donors with one fully mismatched HLA haplotype. N Engl J Med 1998, 339: 1186–1193.PubMedView Article
- Ruggeri L, Capanni M, Urbani E, Perruccio K, Shlomchik WD, Tosti A, Posati S, Rogaia D, Frassoni F, Aversa F, Martelli MF, Velardi A: Effectiveness of donor natural killer cell alloreactivity in mismatched hematopoietic transplants. Science 2002, 295: 2097–2100.PubMedView Article
- Burmeister T, Marschalek R, Schneider B, Meyer C, Gökbuget N, Schwartz S, Hoelzer D, Thiel E: Monitoring minimal residual disease by quantification of genomic chromosomal breakpoint sequences in acute leukemias with MLL aberrations. Leukemia 2006, 20: 451–457.PubMedView Article
- Meyer C, Schneider B, Reichel M, Angermueller S, Strehl S, Schnittger S, Schoch C, Jansen MW, van Dongen JJ, Pieters R, Haas OA, Dingermann T, Klingebiel T, Marschalek R: Diagnostic tool for the identification of MLL rearrangements including unknown partner genes. Proc Natl Acad Sci U S A 2005, 102: 449–454.PubMed CentralPubMedView Article
- van der Velden VH, Hochhaus A, Cazzaniga G, Szczepanski T, Gabert J, van Dongen JJ: Detection of minimal residual disease in hematologic malignancies by real-time quantitative PCR: principles, approaches, and laboratory aspects. Leukemia 2003, 17: 1013–1034.PubMedView Article
- Moretta L, Locatelli F, Pende D, Marcenaro E, Mingari MC, Moretta A: Killer Ig-like receptor-mediated control of natural killer cell alloreactivity in haploidentical hematopoietic stem cell transplantation. Blood 2011, 117: 764–771.PubMedView Article
- Nguyen S, Beziat V, Roos-Weil D, Vieillard V: Role of natural killer cells in hematopoietic stem cell transplantation: myth or reality? J Innate Immun 2011, 3: 383–394.PubMedView Article
- Norman PJ, Parham P: Complex interactions: the immunogenetics of human leukocyte antigen and killer cell immunoglobulin-like receptors. Semin Hematol 2005, 42: 65–75.PubMedView Article
- Elliott JM, Yokoyama WM: Unifying concepts of MHC-dependent natural killer cell education. Trends Immunol 2011, 32: 364–372.PubMed CentralPubMedView Article
- Held W, Kijima M, Angelov G, Bessoles S: The function of natural killer cells: education, reminders and some good memories. Curr Opin Immunol 2011, 23: 228–233.PubMedView Article
- Scquizzato E, Zambello R, Teramo A, Baesso I, Varotto S, Albergoni MP, Boscaro E, Cesaro S, Pillon M, Calore E, Gazzola MV, Semenzato G, Messina C, Trentin L: KIR/HLA-I mismatching and risk of relapse in paediatric patients undergoing non-haploidentical allogeneic haematopoietic stem cell transplantation. Pediatr Transplant 2011, 15: 198–204.PubMedView Article
- Björklund AT, Schaffer M, Fauriat C, Ringdén O, Remberger M, Hammarstedt C, Barrett AJ, Ljungman P, Ljunggren HG, Malmberg KJ: NK cells expressing inhibitory KIR for non-self-ligands remain tolerant in HLA-matched sibling stem cell transplantation. Blood 2010, 115: 2686–2694.PubMed CentralPubMedView Article
- Sun JY, Dagis A, Gaidulis L, Miller MM, Rodriguez R, Parker P, Nademanee A, Falk P, Rosenthal J, Forman SJ, Senitzer D: Detrimental effect of natural killer cell alloreactivity in T-replete hematopoietic cell transplantation (HCT) for leukemia patients. Biol Blood Marrow Transplant 2007, 13: 197–205.PubMedView Article
- Robinson J, Mistry K, McWilliam H, Ropez R, Marsh SGE: IPD - the immuno polymorphism database. Nucleic Acids Res 2010, 38: D863-D869.PubMed CentralPubMedView Article
- Hokland P, Ommen HB: Towards individualized follow-up in adult acute myeloid leukemia in remission. Blood 2011, 117: 2577–2584.PubMedView Article
- Bacher U, Haferlach T, Fehse B, Schnittger S, Kröger N: Minimal residual disease diagnostics and chimerism in the post-transplant period in acute myeloid leukemia. ScientificWorldJournal 2011, 11: 310–319.PubMedView Article
- Dominietto A: Minimal residual disease markers before and after allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia. Curr Opin Hematol 2011, 18: 381–387.PubMedView Article
- Walter RB, Gooley TA, Wood BL, Milano F, Fang M, Sorror ML, Estey EH, Salter AI, Lansverk E, Chien JW, Gopal AK, Appelbaum FR, Pagel JM: Impact of pretransplantation minimal residual disease, as detected by multiparametric flow cytometry, on outcome of myeloablative hematopoietic cell transplantation for acute myeloid leukemia. J Clin Oncol 2011, 29: 1190–1197.PubMed CentralPubMedView Article
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