Rituximab Chimeric Anti-CD20 Monoclonal Antibody Therapy for Relapsed Indolent Lymphoma: Half of Patients Respond to a Four-Dose Treatment Program.

PURPOSE: The CD20 antigen is expressed on more than 90% of B-cell lymphomas. It is appealing for targeted therapy, because it does not shed or modulate. A chimeric monoclonal antibody more effectively mediates host effector functions and is itself less immunogenic than are murine antibodies. PATIENTS AND METHODS: This was a multiinstitutional trial of the chimeric anti-CD20 antibody, IDEC-C2B8. Patients with relapsed low grade or follicular lymphoma received an outpatient treatment course of IDEC-C2B8 375 mg/m2 intravenously weekly for four doses. RESULTS: From 31 centers, 166 patients were entered. Of this intent-to-treat group, 48% responded. With a median follow-up duration of 11.8 months, the projected median time to progression for responders is 13.0 months. Serum antibody levels were sustained longer after the fourth infusion than after the first, and were higher in responders and in patients with lower tumor burden. The majority of adverse events occurred during the first infusion and were grade 1 or 2; fever and chills were the most common events. Only 12% of patients had grade 3 and 3% grade 4 toxicities. A human antichimeric antibody was detected in only one patient. CONCLUSION: The response rate of 48% with IDEC-C2B8 is comparable to results with single-agent cytotoxic chemotherapy. Toxicity was mild. Attention needs to be paid to the rate of antibody infusion, with titration according to toxicity. Further investigation of this agent is warranted, including its use in conjunction with standard chemotherapy.

An automated approach to determine antibody endpoint titers for COVID-19 by an enzyme-linked immunosorbent assay.

While a variety of therapeutic options continue to emerge for COVID-19 treatment, convalescent plasma (CP) has been used as a possible treatment option early in the pandemic. One of the most significant challenges with CP therapy, however, both when defining its efficacy and implementing its approach clinically, is accurately and efficiently characterizing an otherwise heterogenous therapeutic treatment. Given current limitations, our goal is to leverage a SARS antibody testing platform with a newly developed automated endpoint titer analysis program to rapidly define SARS-CoV-2 antibody levels in CP donors and hospitalized patients. A newly developed antibody detection platform was used to perform a serial dilution enzyme-linked immunosorbent assay (ELISA) for immunoglobulin (Ig)G, IgM, and IgA SARS-CoV-2 antibodies. Data were then analyzed using commercially available software, GraphPad Prism, or a newly developed program developed in Python called TiterScape, to analyze endpoint titers. Endpoint titer calculations and analysis times were then compared between the two analysis approaches. Serial dilution analysis of SARS-CoV-2 antibody levels revealed a high level of heterogeneity between individuals. Commercial platform analysis required significant time for manual data input and extrapolated endpoint titer values when the last serial dilution was above the endpoint cutoff, occasionally producing erroneously high results. By contrast, TiterScape processed 1008 samples for endpoint titer results in roughly 14 minutes compared with the 8 hours required for the commercial software program analysis. Equally important, results generated by TiterScape and Prism were highly similar, with differences averaging 1.26 ± 0.2 percent (mean ± SD). The pandemic has created unprecedented challenges when seeking to accurately test large numbers of individuals for SARS-CoV-2 antibody levels with a rapid turnaround time. ELISA platforms capable of serial dilution analysis coupled with a highly flexible software interface may provide a useful tool when seeking to define endpoint titers in a high-throughput manner. Immunohematology 2021;37:33-43.While a variety of therapeutic options continue to emerge for COVID-19 treatment, convalescent plasma (CP) has been used as a possible treatment option early in the pandemic. One of the most significant challenges with CP therapy, however, both when defining its efficacy and implementing its approach clinically, is accurately and efficiently characterizing an otherwise heterogenous therapeutic treatment. Given current limitations, our goal is to leverage a SARS antibody testing platform with a newly developed automated endpoint titer analysis program to rapidly define SARS-CoV-2 antibody levels in CP donors and hospitalized patients. A newly developed antibody detection platform was used to perform a serial dilution enzyme-linked immunosorbent assay (ELISA) for immunoglobulin (Ig)G, IgM, and IgA SARS-CoV-2 antibodies. Data were then analyzed using commercially available software, GraphPad Prism, or a newly developed program developed in Python called TiterScape, to analyze endpoint titers. Endpoint titer calculations and analysis times were then compared between the two analysis approaches. Serial dilution analysis of SARS-CoV-2 antibody levels revealed a high level of heterogeneity between individuals. Commercial platform analysis required significant time for manual data input and extrapolated endpoint titer values when the last serial dilution was above the endpoint cutoff, occasionally producing erroneously high results. By contrast, TiterScape processed 1008 samples for endpoint titer results in roughly 14 minutes compared with the 8 hours required for the commercial software program analysis. Equally important, results generated by TiterScape and Prism were highly similar, with differences averaging 1.26 ± 0.2 percent (mean ± SD). The pandemic has created unprecedented challenges when seeking to accurately test large numbers of individuals for SARS-CoV-2 antibody levels with a rapid turnaround time. ELISA platforms capable of serial dilution analysis coupled with a highly flexible software interface may provide a useful tool when seeking to define endpoint titers in a high-throughput manner. Immunohematology 2021;37:33­43.

Transplant-associated thrombotic microangiopathy is an endothelial complication associated with refractoriness of acute GvHD.

There is increasing evidence that endothelial dysfunction is involved in refractoriness of acute GvHD (aGvHD). Here we investigated the hypothesis that another endothelial complication, transplant-associated thrombotic microangiopathy (TMA), contributes to the pathogenesis of aGvHD refractoriness. TMA was retrospectively assessed in 771 patients after allogeneic stem cell transplantation (alloSCT). Incidences of TMA and refractory aGvHD were correlated with biomarkers of endothelial damage obtained before alloSCT for patients receiving or not receiving statin-based endothelial prophylaxis (SEP). Diagnostic criteria for TMA and refractory aGvHD were met by 41 (5.3%) and 76 (10%) patients, respectively. TMA was overrepresented in patients with refractory aGvHD (45.0 vs 2.3% in all other patients, P<0.001). TMA independently increased mortality. Elevated pretransplant suppressor of tumorigenicity-2 and nitrates along with high-risk variants of the thrombomodulin gene were associated with increased risk of TMA. In contrast, SEP abolished the unfavorable outcome predicted by pretransplant biomarkers on TMA risk. Patients on SEP had a significantly lower risk of TMA (P=0.001) and refractory aGvHD (P=0.055) in a multivariate multistate model. Our data provide evidence that TMA contributes to the pathogenesis of aGvHD refractoriness. Patients with an increased TMA risk can be identified pretransplant and may benefit from pharmacological endothelium protection.

Molecular signaling in multiple myeloma: association of RAS/RAF mutations and MEK/ERK pathway activation.

Multiple myeloma (MM) is a plasma cell malignancy that is still considered to be incurable in most cases. A dominant mutation cluster has been identified in RAS/RAF genes, emphasizing the potential significance of RAS/RAF/MEK/ERK signaling as a therapeutic target. As yet, however, the clinical relevance of this finding is unclear as clinical responses to MEK inhibition in RAS-mutant MM have been mixed. We therefore assessed RAS/RAF mutation status and MEK/ERK pathway activation by both targeted sequencing and phospho-ERK immunohistochemistry in 180 tissue biopsies from 103 patients with newly diagnosed MM (NDMM) and 77 patients with relapsed/refractory MM (rrMM). We found a significant enrichment of RAS/BRAF mutations in rrMM compared to NDMM (P=0.011), which was mainly due to an increase of NRAS mutations (P=0.010). As expected, BRAF mutations were significantly associated with activated downstream signaling. However, only KRAS and not NRAS mutations were associated with pathway activation compared to RAS/BRAFwt (P=0.030). More specifically, only KRASG12D and BRAFV600E were consistently associated with ERK activation (P<0.001 and P=0.006, respectively). Taken together, these results suggest the need for a more specific stratification strategy consisting of both confirmation of protein-level pathway activation as well as detailed RAS/RAF mutation status to allow for a more precise and more effective application of targeted therapies, for example, with BRAF/MEK inhibitors in MM.

Addition of rituximab to CHOP-like chemotherapy in first line treatment of primary mediastinal B-cell lymphoma.

BACKGROUND: The addition of rituximab (R) to CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone) -like therapy has improved survival in primary mediastinal B-cell lymphoma (PMBCL) patients. However, these results were obtained in young low risk patients and a reevaluation in an unselected patient cohort is warranted. METHODS: In this study, we analyzed 80 PMBCL patients treated with a CHOP-based regimen with and without rituximab. RESULTS: In the non-rituximab cohort 10-year progression free survival (PFS) was 67% and 10-year overall survival (OS) was 72% versus a PFS of 95% and a OS of 92% in the rituximab group, PFS P = 0.001, OS P = 0.023. A subgroup PFS analysis by international prognostic index (IPI) risk revealed that all risk groups benefit from addition of rituximab to induction chemotherapy. In addition, OS probability was higher in the group of non-low risk patients who were treated with rituximab compared to those patients who did not receive rituximab (P = 0.035). In multivariate analysis, only addition of rituximab to induction chemotherapy and reaching complete remission (CR) after first line therapy had a beneficial effect on both PFS and OS, whereas IPI, age, upfront high dose (HD) chemotherapy/autologous blood stem cell transplantation (ABSCT) and rituximab maintenance had no impact on survival. CONCLUSIONS: Our data demonstrate a survival benefit in unselected PMBCL patients treated with CHOP-like induction regimen and additional rituximab independently of the IPI risk score.

Characteristics and outcome of patients with therapy-related acute promyelocytic leukemia front-line treated with or without arsenic trioxide.

Therapy-related acute promyelocytic leukemia (t-APL) is relatively rare, with limited data on outcome after treatment with arsenic trioxide (ATO) compared to standard intensive chemotherapy (CTX). We evaluated 103 adult t-APL patients undergoing treatment with all-trans retinoic acid (ATRA) alone (n=7) or in combination with ATO (n=24), CTX (n=53), or both (n=19). Complete remissions were achieved after induction therapy in 57% with ATRA, 100% with ATO/ATRA, 78% with CTX/ATRA, and 95% with CTX/ATO/ATRA. Early death rates were 43% for ATRA, 0% for ATO/ATRA, 12% for CTX/ATRA and 5% for CTX/ATO/ATRA. Three patients relapsed, two developed therapy-related acute myeloid leukemia and 13 died in remission including seven patients with recurrence of the prior malignancy. Median follow-up for survival was 3.7 years. None of the patients treated with ATRA alone survived beyond one year. Event-free survival was significantly higher after ATO-based therapy (95%, 95% CI, 82-99%) as compared to CTX/ATRA (78%, 95% CI, 64-87%; P=0.042), if deaths due to recurrence of the prior malignancy were censored. The estimated 2-year overall survival in intensively treated patients was 88% (95% CI, 80-93%) without difference according to treatment (P=0.47). ATO when added to ATRA or CTX/ATRA is feasible and leads to better outcomes as compared to CTX/ATRA in t-APL.

Pan-mutant-IDH1 inhibitor BAY1436032 is highly effective against human IDH1 mutant acute myeloid leukemia in vivo.

Neomorphic mutations in isocitrate dehydrogenase 1 (IDH1) are frequently found in several human cancer types including acute myeloid leukemia (AML) and lead to the production of high levels of the oncometabolite (R)-2-hydroxyglutarate (R-2HG). Here we report the characterization of BAY1436032, a novel pan-mutant IDH1 inhibitor, both in vitro and in vivo. BAY1436032 specifically inhibits R-2HG production and colony growth, and induces myeloid differentiation of AML cells carrying IDH1R132H, IDH1R132C, IDH1R132G, IDH1R132L and IDH1R132S mutations. In addition, the compound impacts on DNA methylation and attenuates histone hypermethylation. Oral administration of BAY1436032 led to leukemic blast clearance, myeloid differentiation, depletion of leukemic stem cells and prolonged survival in two independent patient-derived xenograft IDH1 mutant AML mouse models. Together, BAY1436032 is highly effective against all major types of IDH1 mutant AML.

GvL effects in T-prolymphocytic leukemia: evidence from MRD kinetics and TCR repertoire analyses.

Allogeneic stem cell transplantation (alloSCT) is used for treating patients with T-prolymphocytic leukemia (T-PLL). However, direct evidence of GvL activity in T-PLL is lacking. We correlated minimal residual disease (MRD) kinetics with immune interventions and T-cell receptor (TCR) repertoire diversity alterations in patients after alloSCT for T-PLL. Longitudinal quantitative MRD monitoring was performed by clone-specific real-time PCR of TCR rearrangements (n=7), and TCR repertoire diversity assessment by next-generation sequencing (NGS; n=3) Although post-transplant immunomodulation (immunosuppression tapering or donor lymphocyte infusions) resulted in significant reduction (>1 log) of MRD levels in 7 of 10 occasions, durable MRD clearance was observed in only two patients. In all three patients analyzed by TCR-NGS, MRD responses were reproducibly associated with a shift from a clonal, T-PLL-driven profile to a polyclonal signature. Novel clonotypes that could explain a clonal GvL effect did not emerge. In conclusion, TCR-based MRD quantification appears to be a suitable tool for monitoring and guiding treatment interventions in T-PLL. The MRD responses to immune modulation observed here provide first molecular evidence for GvL activity in T-PLL which, however, may be often only transient and reliant on a poly-/oligoclonal rather than a monoclonal T-cell response.

Performance assessment and benchmarking of autologous peripheral blood stem cell collection with two different apheresis devices.

BACKGROUND: Collection of peripheral blood stem cells (PBSCs) for autologous transplantation is a well-established process. As a new generation of leukapheresis (LP) machines has been launched, measures of benchmarking and quality control need to be defined in order to ensure consistent collection performance. OBJECTIVES: The goal of this project was to establish and evaluate a benchmarking system for autologous PBSC collection. METHODS: This retrospective study evaluated PBSC collection data of 198 patients with symptomatic multiple myeloma in first-line therapy who underwent LP in 2013 and 2014 at our institution. Half the patients in 2014 were assigned randomly to undergo LP with the new Terumo BCT Spectra Optia (Terumo BCT, Garching, Germany), while the COBE Spectra (Terumo BCT) was used in all other cases. In 2014, we implemented a previously described formula for predicting daily CD34+ cell collection. As a benchmark, we developed the performance ratio: collected/predicted CD34+ cells. RESULTS: There was no significant difference in the number of collected CD34+ cells, the collection efficiency (collected/processed CD34+ cells) and performance ratio between the two collection devices and between LP procedures in 2013 and 2014. CONCLUSIONS: We present a comprehensive benchmarking tool that is easy to implement, requires minimal expense and allows specific adjustment of LP parameters for optimisation of LP performance. With this approach, we could confirm the equal efficiency of the two compared apheresis systems.

Pretransplant NPM1 MRD levels predict outcome after allogeneic hematopoietic stem cell transplantation in patients with acute myeloid leukemia.

The objective was to evaluate the prognostic impact of pre-transplant minimal residual disease (MRD) as determined by real-time quantitative polymerase chain reaction in 67 adult NPM1-mutated acute myeloid leukemia patients receiving allogeneic hematopoietic stem cell transplantation (HSCT). Twenty-eight of the 67 patients had a FLT3-ITD (42%). Median age at transplantation was 54.7 years, median follow-up for survival from time of allografting was 4.9 years. At transplantation, 31 patients were in first, 20 in second complete remission (CR) and 16 had refractory disease (RD). Pre-transplant NPM1 MRD levels were measured in 39 CR patients. Overall survival (OS) for patients transplanted in CR was significantly longer as compared to patients with RD (P=0.004), irrespective of whether the patients were transplanted in first or second CR (P=0.74). There was a highly significant difference in OS after allogeneic HSCT between pre-transplant MRD-positive and MRD-negative patients (estimated 5-year OS rates of 40 vs 89%; P=0.007). Multivariable analyses on time to relapse and OS revealed pre-transplant NPM1 MRD levels >1% as an independent prognostic factor for poor survival after allogeneic HSCT, whereas FLT3-ITD had no impact. Notably, outcome of patients with pre-transplant NPM1 MRD positivity >1% was as poor as that of patients transplanted with RD.

Minimal renal toxicity after Rituximab DHAP with a modified cisplatin application scheme in patients with relapsed or refractory diffuse large B-cell lymphoma.

BACKGROUND: Rituximab (R) in combination with DHAP is a widely accepted salvage regimen for patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL). A common adverse effect of this protocol is renal toxicity which may result in treatment discontinuation. Assuming that a lower single dose of cisplatin over several days would reduce renal toxicity, our institution has chosen to administer cisplatin in a dosage of 25 mg/m(2) per day as a 3-h infusion over 4 consecutive days. METHODS: In this study, we analyzed the renal function of 122 patients with relapsed or refractory DLBCL treated with R-DHAP at our institution. Overall, 256 R-DHAP cycles were administered. 31 (25%), 61 (50%), 14 (12%) and 16 (13%) patients received one, two, three or four R-DHAP courses, respectively. RESULTS: A glomerular filtration rate (GFR) decrease was observed after each R-DHAP cycle. However, in none of the subgroups the median GFR was lower than 60 ml/min/1.73 m(2). In most patients, only renal impairment stage I and II was observed. Renal impairment stage III was seen in 10% and stage IV only in 1% of patients. CONCLUSION: We conclude that a modified R-DHAP regimen with administration of cisplatin 25 mg/m(2) over 4 consecutive cycles leads only to minimal renal toxicity.

Pretreatment d-2-hydroxyglutarate serum levels negatively impact on outcome in IDH1-mutated acute myeloid leukemia.

Mutations in isocitrate dehydrogenases (IDHs) 1 and 2 frequently occur in acute myeloid leukemia (AML) and result in the production of the oncometabolite d-2-hydroxyglutarate (D2HG). D2HG has been shown to promote leukemogenesis even in the absence of mutated IDH, but the prognostic significance of pretreatment serum D2HG levels in patients with IDH-mutated AML is unclear. We measured D2HG serum levels in 84 patients with IDH-mutated AML treated in the prospective, randomized multicenter AML2003 trial of the German Study Alliance Leukemia. Multivariate Cox regression showed D2HG levels to negatively impact on event-free survival (EFS) as a continuous variable in the entire IDH(mut) cohort (P=0.04), with no effect on overall survival (OS). In a subgroup analysis, the negative impact of D2HG on EFS was found to be restricted to patients with mutations in IDH1 (P=0.003), adjusted for age, leukocyte count, serum lactate dehydrogenase and European LeukemiaNet risk score. We thus conclude that pretreatment D2HG serum levels may yield prognostic information in patients with IDH1-mutated, but not in IDH2-mutated AML, possibly due to different subcellular localizations of IDH1 and IDH2.

Long-term outcome of patients with newly diagnosed chronic myeloid leukemia: a randomized comparison of stem cell transplantation with drug treatment.

Tyrosine kinase inhibitors represent today's treatment of choice in chronic myeloid leukemia (CML). Allogeneic hematopoietic stem cell transplantation (HSCT) is regarded as salvage therapy. This prospective randomized CML-study IIIA recruited 669 patients with newly diagnosed CML between July 1997 and January 2004 from 143 centers. Of these, 427 patients were considered eligible for HSCT and were randomized by availability of a matched family donor between primary HSCT (group A; N=166 patients) and best available drug treatment (group B; N=261). Primary end point was long-term survival. Survival probabilities were not different between groups A and B (10-year survival: 0.76 (95% confidence interval (CI): 0.69-0.82) vs 0.69 (95% CI: 0.61-0.76)), but influenced by disease and transplant risk. Patients with a low transplant risk showed superior survival compared with patients with high- (P<0.001) and non-high-risk disease (P=0.047) in group B; after entering blast crisis, survival was not different with or without HSCT. Significantly more patients in group A were in molecular remission (56% vs 39%; P=0.005) and free of drug treatment (56% vs 6%; P<0.001). Differences in symptoms and Karnofsky score were not significant. In the era of tyrosine kinase inhibitors, HSCT remains a valid option when both disease and transplant risk are considered.

The influence of rituximab, high-dose therapy followed by autologous stem cell transplantation, and age in patients with primary CNS lymphoma.

For patients with diffuse large B cell lymphoma without the involvement of the CNS, the addition of rituximab to standard chemotherapy has significantly improved survival. In this single-center, retrospective analysis, a total of 81 primary CNS lymphoma (PCNSL) patients treated in our institution between 2000 and 2011 were included. Beside first-line chemotherapy with or without rituximab, we evaluated the impact of age (≤/>60 years), autologous stem cell transplantation (ASCT +/-), and other factors upon overall survival (OS) and progression-free survival (PFS). In patients treated with rituximab (n = 27), 3-year OS was 77.8 % (95 % confidence interval (CI) 62-93 %). In contrast, in patients treated without rituximab (n = 52), 3-year OS was only 39.9 % (CI 27-53 %, Fig. 1). The difference in OS was significant in the univariate (p = 0.002) as well as in the multivariate analysis (p = 0.049, hazard ratio (HR) = 0.248). Patients ≤60 years of age (n = 28) had a 3-year OS of 78.2 % (CI 63-94 %); in patients >60 years (n = 51), 3-year OS was 38.7 % (CI 25-52 %). Patients who received high-dose therapy and ASCT had a 3-year OS of 85.2 % (CI 72-99 %), and 65.1 % were alive up to the time of analysis (range 9-131 months). Without ASCT, median OS was only 16 months (CI 11-21) and 3-year OS was 35.2 % (CI 22-48 %). Age and ASCT were significantly associated with better OS in univariate (p = 0.002 and p < 0.001) as well in multivariate analysis (p = 0.004, HR = 0.023 and p = 0.001, HR = 0.014). Rituximab treatment, ASCT, and age are independent prognostic factors for OS in the first-line treatment of PCNSL.

Allogeneic hematopoietic stem cell transplantation for poor-risk CLL: dissecting immune-modulating strategies for disease eradication and treatment of relapse.

To elucidate factors contributing to the effectiveness of allogeneic hematopoietic stem cell transplantation (alloHCT) in high-risk CLL, immune interventions, GvHD and clinical outcome of 77 consecutive patients allografted for CLL were analyzed. Immune modulation (immunosuppression tapering, rituximab-augmented donor lymphocyte infusions) was guided by minimal residual disease (MRD) monitoring and commenced at a median of 91 (22-273) days after alloHCT, resulting in a probability of being event free and MRD-negative 1 year after transplant of 57% (84% in those encountering chronic GvHD). Patients who were event free and MRD-negative at the 12-month landmark had a 4-year PFS of 77% and largely remained durably MRD-negative if MRD clearance had occurred subsequent to immune modulation. Three-year overall survival, PFS, relapse incidence and non-relapse mortality of all 77 patients were 69, 57, 26 and 24%, respectively. Survival was not affected by EBMT risk category but by active disease at alloHCT, which could not be overcome by intensification of conditioning. Twenty-three patients who experienced relapse post alloHCT had a survival of 56% at 2 years after CLL recurrence. In conclusion, MRD-guided immune modulation after alloHCT for high-risk CLL can provide durable MRD clearance in more than half of the patients.

Long-term ovarian function in women treated with CHOP or CHOP plus etoposide for aggressive lymphoma.

BACKGROUND: Chemotherapy-associated ovarian damage comprises not only infertility, but also premature menopause. The latter has been reported as a consequence of alkylating chemotherapy for breast cancer or Hodgkin's lymphoma. In this study, we assessed the long-term impact of CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone)-like regimens on ovarian function in patients with aggressive non-Hodgkin lymphoma (NHL). PATIENTS AND METHODS: Long-term survivors after CHOP or CHOP plus etoposide (CHOEP) treatment within the Mabthera International Trial or the NHL-B1 trial of the German NHL Study Group were requested to respond to a questionnaire and to consent to blood sampling for hormone assessment. RESULTS: A total of 46 of 81 contacted patients with a median age of 32.5 years at the time of enrolment into the aforementioned clinical trials responded to the questionnaire. The median follow-up after completion of treatment was 14 years. Last menstrual bleeding occurred significantly earlier in patients compared with the general population (47 versus 51 years, P < 0.0001). In comparison to the distribution of menopausal symptoms in the general population, the percentage of women with moderate or severe menopausal symptoms was increased. In 23 patients who agreed to participate in laboratory analyses, anti-Muller hormone as a marker of ovarian reserve was decreased when compared with correspondent age groups of the general population. CONCLUSION: Although most female patients regain fertility after CHOP-like chemotherapy, late ovarian impairment occurs frequently. Therefore, awareness of such delayed side-effects at the time of counselling is of importance.

Hematopoietic cell transplantation in patients with intermediate and high-risk AML: results from the randomized Study Alliance Leukemia (SAL) AML 2003 trial.

The optimal timing of allogeneic hematopoietic stem cell transplantation (HCT) in acute myeloid leukemia (AML) is controversial. We report on 1179 patients with a median age of 48 years who were randomized upfront. In the control arm, sibling HCT was scheduled in the first complete remission for intermediate-risk or high-risk AML and matched unrelated HCT in complex karyotype AML. In the experimental arm, matched unrelated HCT in first remission was offered also to patients with an FLT3-ITD (FMS-like tyrosine kinase 3-internal tandem duplication) allelic ratio >0.8, poor day +15 marrow blast clearance and adverse karyotypes. Further, allogeneic HCT was recommended in high-risk AML to be performed in aplasia after induction chemotherapy. In the intent-to-treat (ITT) analysis, superiority of the experimental transplant strategy could not be shown with respect to overall survival (OS) or event-free survival. As-treated analyses suggest a profound effect of allogeneic HCT on OS (HR 0.73; P=0.002) and event-free survival (HR 0.67; P<0.001). In high-risk patients, OS was significantly improved after allogeneic HCT in aplasia (HR 0.64; P=0.046) and after HCT in remission (HR 0.74; P=0.03). Although superiority of one study arm could not be demonstrated in the ITT analysis, secondary analyses suggest that early allogeneic HCT is a promising strategy for patients with high-risk AML.

Inhibition of intestinal tumor formation by deletion of the DNA methyltransferase 3a.

Aberrant de novo methylation of DNA is considered an important mediator of tumorigenesis. To investigate the role of de novo DNA methyltransferase 3a (Dnmt3a) in intestinal tumor development, we analyzed the expression of Dnmt3a in murine colon crypts, murine colon adenomas and human colorectal cancer using RNA fluorescence in situ hybridization (FISH), quantitative PCR and immunostaining. Following conditional deletion of Dnmt3a in the colon of APC((Min/+)) mice, we analyzed tumor numbers, genotype of macroadenomas and laser dissected microadenomas, global and regional DNA methylation and gene expression. Our results showed increased Dnmt3a expression in colon adenomas of APC((Min/+)) mice and human colorectal cancer samples when compared with control tissue. Interestingly, in tumor tissue, RNA FISH analysis showed highest Dnmt3a expression in Lgr5-positive stem/progenitor cells. Deletion of Dnmt3a in APC((Min/+)) mice reduced colon tumor numbers by ~40%. Remaining adenomas and microadenomas almost exclusively contained the non-recombined Dnmt3a allele; no tumors composed of the inactivated Dnmt3a allele were detected. DNA methylation was reduced at the Oct4, Nanog, Tff2 and Cdkn1c promoters and expression of the tumor-suppressor genes Tff2 and Cdkn1c was increased. In conclusion, our results show that Dnmt3a is predominantly expressed in the stem/progenitor cell compartment of tumors and that deletion of Dnmt3a inhibits the earliest stages of intestinal tumor development.