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Background: The DNA methyltransferase 3A (DNMT3A) is one of the most frequent mutated genes in AML with a hot spot mutation at codon R882 in 80% of the DNMT3Amut cases. In most of the studies ...DNMT3Amut predicts for poor overall (OS) and relapse-free survival (RFS). Recently, DNMT3Amut have been associated with age-related clonal hematopoiesis, and they have been identified in early preleukemic stem cells. These findings suggest that DNMT3Amut represents an early event in leukemogenesis and may be part of the leukemia founder clone in most AMLs harboring a DNMT3Amut. We thought to address the question whether MRD monitoring in DNMT3Amut patients (pts) can be used for prognostic classification and risk stratification in these pts.
Aims: We monitored MRD for the most common DNMT3Amut (DNMT3Amut -R882H, n=126 and -R882C, n=55) in a large cohort of adult AML pts entered on three AMLSG treatment trials AML HD98A (n=14; NCT00146120), AMLSG 07-04 (n=86; NCT00151242), AMLSG 09-09 (n=81; NCT00893399).
Methods: DNMT3Amut MRD monitoring was performed using a cDNA-based RQ-PCR-assay by TaqMan technology with a sensitivity between 10-3 and 10-4. MRD levels are reported as normalized values of DNMT3Amut transcripts per 104ABL1 transcripts (DNMT3Amut/104ABL1).
Results: In total, 1,494 samples bone marrow (BM), n=798; peripheral blood (PB), n=696 from 181 DNMT3Amut pts were analysed diagnosis, n=287; during therapy, n=840; follow-up, n=367. Median age of the patients was 50 years (range, 22 to 78); median BM DNMT3Amut transcript level (TL) at the time of diagnosis was 12690 (range, 1396-54280). There was no significant association of TL with presenting clinical characteristics, such as age, white blood cell count, platelet count, BM and PB blasts, lactate dehydrogenase, or with mutations in NPM1, FLT3 ITD and TKD, CEBPA and cytogenetics. DNMT3Amut TL as log 10 transformed continuous variable and stratified by study did not impact OS (p=0.29), RFS (p=0.17) and EFS (p=0.28). Comparing TL after double induction (DI) did not show a significant difference between 13 patients without complete remission (CR) and 117 in CR (12983 and 12595, respectively; p=0.52). In Cox regression analyses, BM DNMT3Amut TL as log 10 transformed continuous variable during therapy did not impact the clinical endpoints death and relapse. In general, DNMT3Amut TL during therapy (after induction I, induction II, consolidation I and II) were significantly higher in BM than in PB (p=0.01; p=0.05; p=0.004; p=0.008, respectively). We observed the greatest TL reduction (one log) after induction I, whereas subsequent cycles of therapy did not significantly influence TL. To evaluate the impact of DNMT3Amut MRD monitoring with regard to the clinical endpoints OS, cumulative incidence of relapse (CIR) and remission duration (RD) after DI and after end of therapy (ET) we used different statistical approaches; all survival analyses were stratified by study. After DI and ET, only 8/90 and 4/88 BM samples became MRD negative. At these two time-points MRD positivity did not significantly impact OS (p=0.99; p=0.74), CIR (p=0.73; p=0.15) and RD (p=0.83; p=0.16). Next, we investigated the MRD DNMT3Amut log10-reduction (compared to levels at diagnosis) after DI and ET using the median as a cut-off. Again, we could not detect a significant correlation for pts with a higher TL reduction compared with pts with a lower TL reduction for OS and RD after DI and ET (p=0.83; p=0.30; p=0.04; p=0.21, respectively). Lastly, we evaluated the BM DNMT3Amut TL as 4 increasing equally sized intervals according to the quartiles of the distribution. There was no prognostic impact after DI on OS and RD (p=0.53; p=0.89) and ET (p=0.76; p=0.53). When combining PB and BM samples for the analyses we could not find significant changes in the results.
Conclusion: In our study most pts had persistent DNMT3Amut TL with only a minority achieving MRD negativity, a finding that supports the presence of persistent clonal hematopoiesis in hematologic remission. Using different explorative approaches, DNMT3Amut TL did not impact clinical outcome neither during therapy nor during follow-up.
Horst:Gilead: Honoraria, Research Funding; Pfizer: Research Funding; MSD: Research Funding; Boehringer Ingleheim: Research Funding; Amgen: Honoraria, Research Funding. Schlenk:Arog: Honoraria, Research Funding; Boehringer-Ingelheim: Honoraria; Janssen: Membership on an entity's Board of Directors or advisory committees; Teva: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees.
Abstract ▪670▪This icon denotes a clinically relevant abstract
Relapsed/refractory B-precursor ALL in adults has a dismal prognosis with only 35–40% of patients reaching a hematological complete ...remission (CR) with a median overall survival of 4–6 months. An exploratory phase II trial was conducted in this patient population with blinatumomab, a bispecific T-cell engaging (BiTE®) antibody that directs cytotoxic T-cells to CD19 expressing target cells.
The primary endpoint was hematological CR or CR with partial hematological recovery (CRh*) within 2 cycles of blinatumomab. Secondary endpoints included overall survival (OS) and safety.
Blinatumomab was administered by continuous intravenous infusion for 28 days followed by a 14-day treatment-free interval. Responding patients had the option to receive 3 additional cycles of treatment or to proceed to allogeneic hematopoietic stem cell transplantation (HSCT). Three dosing regimens were explored (Table 1) to identify the optimal regimen with respect to efficacy and toxicity.
36 patients were treated; 26 out of the 36 treated patients (72%) achieved a hematological CR/CRh*. Ten out of 26 (38%) responders had a CRh*. 24 out 26 (92%) responders achieved also a molecular response (minimal residual disease level below 10−4 as measured by PCR) within the first 2 cycles. Twenty out of 21 (95%) patients in first relapse responded whereas only 6 out of 15 (40%) of the remaining patients achieved a hematological CR/CRh*.
Thirteen patients proceeded to allogeneic HSCT in CR/CRh* after blinatumomab treatment, and one of them developed a medullary CD19− relapse after allogeneic HSCT. The other 13 responders did not receive allogeneic HSCT. Eight of these 13 patients relapsed: 2 relapses were CD19− (1 medullary and 1 extramedullary); 3 were CD19+ (1 medullary and 2 extramedullary), and 3 were with pending CD19 status (all 3 medullary).Table 1:Summary of Dose Cohorts and OutcomesCohortPatients TreatedWeek 1, Cycle 1 μg/m2/dayWeek 2, Cycle 1 μg/m2/dayWeeks 3-4, Cycle 1 and Subsequent Cycles μg/m2/dayCR/CRh*171515155 (71%)2a (Final dose)5515154 (80%)2b6515304 (67%)3 (Final dose)185151513 (72%)Total3626 (72%)
The median survival for all 36 treated patients is 9.0 months with a median follow-up time for OS of 10.7 months. For patients who achieved a CR/CRh*, the median survival is 14.1 months whereas for patients who failed blinatumomab therapy the median survival is 6.6 months.
Cytokine release syndrome (CRS) and CNS events were reported as medically important events. Two patients with high tumor burden and no cytoreductive prephase required treatment interruption or discontinuation. CRS syndrome could be either prevented or treated by adapting a dexamethasone regimen for patients resulting in no further treatment interruption due to CRS. Fully reversible adverse drug events of the CNS leading to treatment interruption were observed in 6 patients: 3 patients with seizures and 3 patients with encephalopathy. CNS symptoms fully resolved, and all 6 patients were able to resume treatment at a lower dose; however, 2 out of these 6 patients had a recurrent event and permanently discontinued. One patient stopped treatment due to fungal infection leading to death.
As final dose and schedule, 5 μg/m2/day in week 1 and 15 μg/m2/day for the remaining treatment (as in cohorts 2a and 3) was selected for further investi-gation based on safety and efficacy considerations. In the extension cohort, cohort 3 (n=18), the most common treatment emergent adverse events (TEAE) were pyrexia (70%), headache (39%), tremor (30%) and fatigue (30%).
The final dosing regimen of blinatumomab produced exceptionally high complete hematological and molecular remission rates and was well-tolerated. Updated follow-up information regarding duration of response and survival will be presented. A global phase II study to confirm these data is being conducted.
Topp:Amgen: Consultancy; Affimed: Consultancy. Goekbuget:AMGEN: Consultancy, Honoraria, Research Funding. Zugmaier:Amgen: Employment. Mergen:Amgen Research Munich GmbH: Employment. Bargou:Amgen: Consultancy, Honoraria.
Activating mutations in the receptor tyrosine kinase FLT3 occur in roughly 30% of acute myeloid leukemia (AML) patients (pts), implicating FLT3 as a potential target for kinase inhibitor therapy. The ...multi-targeted kinase inhibitor midostaurin (PKC412) shows potent activity against FLT3 as a single agent but also in combination with intensive chemotherapy. Besides its mere presence, the allelic ratio as well as ITD insertion site within the FLT3 gene had been reported as prognostic factors in FLT3-ITD positive AML. Furthermore, pharmacokinetic analyses revealed clinically important interactions between potent CYP3A4 inhibitors, such as azoles, and midostaurin.
To evaluate the pharmacodynamic activity of midostaurin measured as inhibition of the degree of phosphorylated FLT3 (pFLT3) in correlation to co-medication and outcome data.
The study includes intensively treated adults (age 18-70 years) with newly diagnosed FLT3-ITD positive AML enrolled in the ongoing single-arm phase-II AMLSG 16-10 trial (NCT: NCT01477606). Pts with acute promyelocytic leukemia are not eligible. The presence of FLT3-ITD is analyzed by Genescan-based fragment-length analysis (allelic ratio >0.05 required to be FLT3-ITD positive). Induction therapy consists of daunorubicin (60 mg/m², d1-3) and cytarabine (200 mg/m², continuously, d1-7); midostaurin 50 mg twice daily is applied from day 8 onwards until 48h before start of the next treatment cycle. For consolidation therapy, pts proceed to allogeneic hematopoietic stem cell transplantation (HSCT) as first priority; if allogeneic HSCT is not possible pts receive three cycles of age-adapted high-dose cytarabine in combination with midostaurin from day 6 onwards. In all pts maintenance therapy for one year is intended. A total sample size of n=142 is planned to show an improvement in event-free survival from 25% after 2 years to 37.5%. Plasma inhibitory activity assay (PIA) for pFLT3 is performed as previously described (Levis MJ, et al. Blood 2006; 108:3477-83). For PIA, measured time points include day 15 of induction therapy, the end of each treatment cycle and every three months during maintenance therapy.
To date, 72 pts (median age, 54.5 years; range, 29-69 years) have been included and PIA was performed so far in 37 pts during induction therapy. Median pFLT3 inhibition after one week of midostaurin intake measured on day 15 of cycle 1 (C1D15) was 57.5% (range, 14.2-93.7%) with 2 of 31 pts showing inhibition >85%. At the end of the first induction cycle (C1end), median inhibition was 60.3% (range, 0-99.8%); here, 6 of 37 pts had an inhibition >85%. Co-medication with azoles was present in 7 of 23 pts at C1D15 and 13 of 28 pts at C1end. There was no significant difference in pFLT3 inhibition either on C1D15 (p=0.79) or at C1end (p=0.70) between pts on (median pFLT3 inhibition: 52.5%) or off (median pFLT3 inhibition 57.5%) azoles. Response data were available in 56 pts: complete remission (CR) was achieved in 78.5%; rates of early death and refractory disease (RD) were 9% and 12.5%, respectively. In first analyses, there was no difference in pFLT3 inhibition in pts achieving CR (n=30) as compared to those with RD (n=3; p=0.99). In contrast to our previously published data from three historical trials without a FLT3 inhibitor which showed that high allelic ratio was associated with low CR rates (Kayser S, et al. Blood 2009;114:2386-92), in the current trial CR rates remained high (81.5%) despite of a high allelic ratio above the median (>0.58). In addition, we did not see a negative prognostic impact of ITD insertion site within the tyrosine kinase domain of the FLT3 gene (p=0.99). Analyses are currently ongoing, measurement of FLT3 ligand levels and evaluation of pharmacokinetics of midostaurin are also intended.
The addition of 50 mg midostaurin twice daily to intensive induction therapy resulted in a moderate pFLT3 inhibition during induction therapy. Nonetheless, CR rates are promising, especially in pts with unfavorable FLT3-ITD characteristics. Concomitant azoles do not appear to significantly influence pFLT3 inhibitory activity of midostaurin.
Levis:Ambit Biosciences: Consultancy. Schlenk:Ambit: Honoraria; Chugai: Research Funding; Novartis: Research Funding; Pfizer: Research Funding; Amgen: Research Funding.
Abstract 878
PTLD is a rare disorder affecting 1 to 10% of transplant recipients. Data from prospective trials is scarce. For more than 30 years, reduction of immunosuppression has been the basis of ...treatment despite generally low efficacy. The introduction of rituximab monotherapy has significantly improved remission rates in CD20-positive B-cell PTLD, but long-term disease control remains problematic. CHOP chemotherapy can achieve this goal, but is associated with a high lethal toxicity of 20% to 30%. Thus, we initiated an international multicenter phase II trial to investigate whether the subsequent application of 4 courses of rituximab and 4 cycles of CHOP-21 would improve the outcome.
Treatment-naive adult solid organ transplant recipients diagnosed with CD20-positive PTLD received 4 courses of rituximab (375 mg/m2) once a week followed by 4 weeks without treatment and 4 cycles of 3-weekly CHOP. In case of disease progression during rituximab monotherapy, CHOP was commenced immediately. Supportive therapy with G-CSF was mandatory and antibiotic prophylaxis was recommended. The primary endpoint was response and duration of response. Secondary endpoints were treatment toxicity and overall survival. Analysis was by intention to treat. This study is registered with EudraCT number 2005-000743-29.
74 patients were enrolled between Jan. 2003 and Dec. 2007. 70 were allocated to treatment (4 excluded due to missing or withdrawn informed consent). Median age at diagnosis of PTLD was 53.3 years (range 16–74 years). The transplanted organs were kidney (29/70), liver (16/70), heart (14/70), lung (4/70), heart + lung (2/70), kidney + pancreas (4/70) and bone marrow (1/70, protocol violation). Median time of follow up was 5.1 years. PTLD occurred late (more than one year after transplantation) in 76%, with disseminated disease (Ann Arbor stage >II) in 74%. Histology was monomorphic in 84% and EBV-association was present in 44%. Patients with EBV-associated PTLD had a significantly different pattern of involvement and a significantly worse performance status. 66/70 patients (94%) received chemotherapy: two had died prior to CHOP and two were considered not eligible. Chemotherapy-induced grade 3/4 leukocytopenia occurred in 68% and grade 3/4 infections in 41% of patients. The planned dose of CHOP was reduced by more than 25% in 14% of patients. Dose reductions were significantly more frequent in EBV-associated PTLD and did correlate with more frequent grade 3/4 infections. Treatment-associated mortality of CHOP was 10.6% (7/66), the majority of which affected rituximab non-responders (5/7). The overall response rate was 90% (67% complete response, see figure 1). Median duration of remission for treatment responders is not yet reached and 74% are progression free at 3 and 5-years (figure 1A). Median overall survival was 6.6 years (figure 2B). EBV-association predicted time to progression (TTP) in adjusted Cox regression analysis (HR: 0.150, p=0.027), but patients with EBV- and non-EBV-associated PTLD demonstrated similar TTP intervals by univariate analysis. Notably, response to rituximab at interim staging predicted TTP (p=0.028) and OS (p=0.014), which was the reason to cease accrual to the protocol in 2007 and introduce risk-stratified sequential treatment (RSST). Display omitted Display omitted
Discussion This is the largest prospective trial in the field of PTLD published so far. Sequential treatment with rituximab and CHOP results in excellent disease control and overall survival in adults with PTLD, adding more than three years of life in comparison to historical results achieved with 1st-line rituximab monotherapy and 2nd-line (chemo)-therapy. TRM after sequential treatment is lower than historically reported for CHOP 1st-line therapy. The lower TRM from CHOP in rituximab responders versus non-responders supports the idea that it is a function of tumor burden. In conclusion, sequential treatment with 4 courses of rituximab followed by 4 cycles of three-weekly CHOP + GCSF provides an excellent standard of care for patients with both EBV-associated and non-EBV-associated B-cell PTLD failing to experience sustained response to upfront reduction of immunosuppression.
Trappe:AMGEN: Research Funding; Mundipharma: Research Funding; CSL Behring: Honoraria, Research Funding; Roche: Consultancy, Honoraria, Research Funding. Oertel:Roche: Employment, Equity Ownership. Leblond:Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees. Salles:Roche and/or Genetech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genzyme: Membership on an entity's Board of Directors or advisory committees; Calistoga/Gilead: Membership on an entity's Board of Directors or advisory committees. Morschhauser:Roche/Genetech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Choquet:Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.
Abstract 252
Adult patients with relapsed/refractory B-precursor acute lymphoblastic leukemia (ALL) have a dismal prognosis with low complete remission (CR) rates with intensive salvage chemotherapy ...which are not durable.
Blinatumomab is a bispecific T-cell engaging (BiTE®) antibody construct that directs cytotoxic T-cells to CD19 expressing B-cells. In collaboration with the German Multicenter Study Group for Adult Lymphoblastic Leukemia (GMALL), an open-label, multicenter, single-arm, exploratory phase II trial is being conducted to evaluate efficacy and safety of blinatumomab in adult patients with relapsed/refractory B-precursor ALL.
The primary endpoint for this trial is the rate of patients who reach CR or CR with partial hematological recovery (CRh*) within 2 cycles of blinatumomab treatment. Secondary endpoints are the rate of minimal residual disease (MRD) response (defined by an MRD level below the quantitative detection limit of 10−4), time to hematological relapse and overall survival.
Blinatumomab is administered by continuous intravenous infusion for 28-days followed by a 14-day treatment-free interval. Responding patients could proceed to allogeneic hematopoietic stem cell transplantation (HSCT) or receive a total of up to 5 cycles of blinatumomab treatment. Three dose levels have been explored as shown in Table 1.Table 1Summary of Dose Cohorts and OutcomesCohortPatients TreatedInitial Dose Week 1, Cycle 1 μg/m2/dayDose Week 2, Cycle 1 μg/m2/dayDose Weeks 3–4, Cycle 1 μg/m2/dayMaintenance Dose, Subsequent Cycles μg/m2/dayCR or CRh*Serious Adverse EventsnPts171515151551562a551515154222b65153030354310 planned5151515n.a.n.a.n.a.
As of June 30, 2011, 43 cycles have been administered to a total of 18 patients (range 1–5; median 2). Twelve out of 18 patients have reached a complete remission within the first 2 cycles of single agent blinatumomab corresponding to a response rate of 67%. Of these 12 responding patients, 75% had complete hematologic recovery of peripheral blood counts. All 12 responders reached MRD negativity within the first 2 cycles and included 3 patients with t(4;11) and 1 patient with Ph-positive B-precursor ALL. Four responders proceeded to allogeneic HSCT; one experienced a CD19-negative hematological relapse after HSCT. Two responders relapsed during treatment; one had a CD19-positive extramedullary, and one a CD19-negative bone marrow relapse. The remaining 6 non-transplanted responders are still in hematological complete remission.
The most common adverse events were pyrexia and chills. In cohort 1, one patient with a high tumor burden developed disseminated intravascular coagulation (DIC)/cytokine release syndrome (CRS) leading to treatment discontinuation. The implementation of a cytoreductive pre-phase and a lower initial dosing at 5μg/m2/day during the first week prevented further treatment discontinuations in such patients. Four patients had fully reversible CNS serious adverse events that led in 1 patient to discontinuation of treatment, and in 3 patients to temporary interruption of treatment. These 3 patients resumed treatment at a lower dose without further interruptions during the following cycles. There were no deaths related to blinatumomab.
Blinatumomab as single agent induced an unprecedented high rate of complete hematological and MRD responses in adult patients with relapsed/refractory B-precursor ALL. A lower dose of 5μg/m2/day for the initial week of treatment, as tested in cohort 2a, demonstrated a favorable safety profile while maintaining efficacy. A maintenance dose of 30μg/m2/day, as tested in cohort 2b, did not further improve the already high efficacy but increased the number of adverse events. Therefore, the dosing of cohort 2a was selected as the basis for cohort 3 and will be applied to further clinical development in this patient population. Updated results of the study will be presented.
Topp:Micromet: Consultancy, Honoraria. Goekbuget:Micromet: Consultancy. Zugmaier:Micromet: Employment. Klappers:Micromet AG: Employment. Mergen:Micromet Inc: Employment. Bargou:Micromet: Consultancy, Honoraria.
Abstract 425
The introduction of all-trans-retinoic acid (ATRA) in front line therapy of acute promyelocytic leukemia (APL) has improved the outcome of all age groups. In the elderly patients (pts), ...multi-morbidity and higher vulnerability to chemotherapy-related toxicity are the main problems reducing the chance of cure. This has led to recommendations to reduce the intensity of therapy in elderly APL pts. We report on the long-term outcome of pts with newly diagnosed APL registered in two prospective studies of the German AML Cooperative Group (AMLCG) from December 1994 until June 2011. The therapy consisted of ATRA and anthracycline/ara-C-based induction and consolidation therapy (TAD/HAM–TAD) followed by maintenance therapy as reported previously in younger APL pts (Lengfelder et al. Leukemia 2009;23:2248–2258). In pts ≥60 years (y), the administration of the second induction cycle (HAM with an age adapted cumulative ara-C dose of 6g/sqm) was at the discretion of the treating physician. After December 2005, the pts were included in the ongoing APL protocol and randomized between the AMLCG strategy and the protocols of the Spanish PETHEMA. Among 295 adult pts with newly diagnosed APL, 83 pts (28%) were ≥60y of age. Seventeen elderly pts (20%) were not enrolled in the study, due to death before start of therapy, contraindications against chemotherapy or concomitant other malignancy. Eleven pts randomized in the PETHEMA arm were excluded from the present analysis to cover homogeneity of therapy. In 53 of 55 pts treated according to the AMLCG protocol, results are available. Median age was 67 y (range 60 to 83); 58% were male, 42% female; 68% had low/intermediate and 32% high risk according to Sanz score. Morphology was FAB M3 in 62%, M3v in 38%. Cytogenetics showed t(15;17) alone in 52%, and combination with other abnormalities in 48% of pts. The bcr1/bcr2 transcript of PML/RARA was found in 41% and the bcr3 transcript in 59% of pts. Forty-four pts (83%) achieved complete remission (CR). Early death (ED) occurred in 9 pts (17%). Median time to ED was 12 days (range 2 to 19) after start of therapy. Causes of ED were bleeding, multi-organ failure and sepsis. Manifest APL differentiation syndrome occurred in 25% of pts and WHO grade ’3 bleeding, fever/infection or cardiac failure in 8%, 43% and 17% of pts, respectively. After consolidation therapy, 96% of pts were in molecular remission. After a median follow up of 5.3 y (1 day to 12.8 y), the 6-year overall (OS), event free (EFS) and relapse free survival (RFS) and the cumulative incidence of relapse (CIR) were 45%, 41%, 50% and 26%, respectively. The outcome was further analyzed according to risk group, number of induction cycles, and age ≥60y to 69y and ≥70y. Pts with pretreatment white blood cell (WBC) count <10 × 109/L (low/intermediate risk; n=36) had a significantly superior outcome compared to pts with high WBC counts (high risk; n=17) resulting in a CR rate of 92% vs. 65% and ED rate of 8% vs. 35%, respectively (p=0.02). The 6-year OS, EFS, RFS and CIR of the low/intermediate risk pts was 56%, 53%, 60% and 14%, respectively, compared to 25%, 15%, 23% and 58% in high risk pts (p=0.006, p=0.0004; p=0.008; p<0.01). All 12 pts, who had received two induction cycles achieved CR, and no relapse occurred so far resulting in a significantly superior outcome compared to patients, who had received only one induction cycle (OS: p=0.007; EFS: p=0.0002; RFS: p=0.01). In the pts ’70y (n=17), 71% entered CR and 29% died from ED. Separated according to low and high WBC counts, the CR rate of this group was 83% vs. 40% and the ED rate 17% vs. 60% (p=0.07), respectively, resulting in an inferior OS (p=0.08) of the pts with high WBC count. Conclusions: Among our elderly pts, we found a high proportion of pts with high risk profile and a high rate of exclusion from the study due to death before the start of therapy or poor condition. In patients included in our study, high WBC count and advanced age are associated with a high risk of ED. The inferior outcome in pts, who received only one induction cycle, suggests that intensification of chemotherapy should be considered in elderly APL pts, if possible. The incorporation of arsenic trioxide might be an alternative, which could be investigated in future trials.
No relevant conflicts of interest to declare.
Abstract 412
Somatic mutations of the ASXL1 (Additional Sex Comb-Like 1) gene on chromosome 20q11.1 were identified in various myeloid malignancies with the highest incidence reported in CMML (∼40%) ...and lower frequencies in MDS, AML, CML, and myeloproliferative neoplasia. The ASXL1 protein has been suggested to act as chromatin modifier and the highly conserved C-terminal plant homeo-domain (PHD) finger is presumably critical for its function. ASXL1 mutations cluster in exon 12 and are mainly frameshift mutations predicted to remove the PHD domain. We and others (Paschka et al., Haematologica 2011;96(s2);425; Chou et al., Blood 2010;116:4086–94) have recently reported first results on the unfavorable prognostic impact of ASXL1 mutations in AML. However, the clinical relevance of these mutations still needs to be elucidated in larger AML cohorts.
Mutational analyses of ASXL1 were performed on diagnostic samples from 1429 patients with AML aged 18 to 61 years. All patients were intensively treated on one of two AMLSG trials AML HD98A (n=745), Schlenk et al., J Clin Oncol. 2010;28:4642–8; AMLSG 07–04(n=684), NCT00151242. GeneScan-based fragment analysis of several amplicons spanning ASXL1 exon 12 was used to screen for ASXL1 mutations. Samples showing altered GeneScan profiles were amplified in a second PCR reaction, and the amplicons were sequenced to confirm the mutation and to determine the mutation type. Patients were also assessed for the presence of NPM1, FLT3 (ITD and TKD), CEBPA, IDH1/2, RUNX1, and DNMT3A mutations by standard PCR-based methods.
ASXL1 mutations were detected in 90 (5.9%) of 1429 patients. All mutations were heterozygous frameshifts predicted to cause loss of the PHD finger. The most common mutation was a duplication of guanine at position 1934 (c.1934dup) identified in 59% (53/90) of the mutated cases. Three other ASXL1 mutations were detected in more than one patient: c.1900_1922del (n=16), c.1934del (n=5), c.1960dup (n=3). The majority of mutations (91%) clustered within or around a glycine-rich protein domain spanning amino acids 642–685. Patients with ASXL1 mutations were older (P<.0001), more frequently males (P=.03), and they more frequently had secondary AML (P=.02). They also showed lower values for WBC (P=.01), bone marrow (P=.0002) and circulating (P=.001) blasts, and LDH serum levels (P=.007). ASXL1 mutations were more frequent in patients exhibiting intermediate-risk cytogenetics (P=.06). Among the ASXL1 mutated cases, 42% were cytogenetically normal (CN), 23% had other intermediate-risk cytogenetics, 26% had high-risk, and 9% low-risk t(8;21) n=7, t(15;17) n=1, no inv(16)/t(16;16) cytogenetics. ASXL1 mutations were associated with RUNX1 (P<.001) and IDH2R140 mutations (P=.006). In contrast, ASXL1 mutations were less frequent in patients with NPM1 (P<.001), FLT3-ITD (P<.001), and DNMT3A (P=.02) mutations. The median follow-up for survival was 4.8 years. Patients with an ASXL1 mutation had an inferior complete remission (CR) rate compared with ASXL1 wildtype patients (57% vs 74%; P<.001); the same was true for the subset of CN-AML (58% vs 77%; P=.04). In both, the entire cohort (P=.04) and in CN-AML (P=.07) ASXL1 mutations were associated with a worse event-free-survival, whereas no impact of these mutations was observed on relapse-free-survival. Patients with ASXL1 mutation had a shorter overall survival (OS) compared to those with ASXL1 wildtype (P=.002; 4-year OS rates, 32% vs 47%). The adverse impact of ASXL1 mutations on OS was also present in the subgroup of CN-AML (P=.009; 4-year OS rates, 33% vs 48%). In multivariable analysis, ASXL1 mutation was in trend an unfavorable factor for OS in CN-AML (hazard ratio: 1.46; P=.087).
ASXL1 mutations were identified in ∼6% of younger AML patients and were associated with intermediate-risk cytogenetics. ASXL1 mutations frequently occurred with RUNX1 and IDH2R140 mutations, and were less frequent in NPM1 and FLT3-ITD mutated AML. ASXL1 mutations were associated with lower CR rate and inferior OS. The exact role of ASXL1 in normal hematopoiesis still needs to be defined in functional studies as well as the potential role of mutated ASXL1 protein in mediating resistance to chemotherapy.
Kündgen:Celgene: Honoraria; Novartis: Honoraria.
Abstract ▪785▪This icon denotes a clinically relevant abstract
FLT3 internal tandem duplications (FLT3-ITD) occur in about 25% of acute myeloid leukemia (AML), are associated with cooperating gene ...mutations (NPM1, DNMT3A), and confer an adverse prognosis. Several studies have indicated that the unfavorable impact of FLT3-ITD is influenced by a number of factors, such as the mutant to wild-type ratio (allelic ratio), insertion site of FLT3-ITD in the beta1 sheet of the tyrosine kinase domain 1, and the molecular background of cooperating mutations.
To evaluate the relative impact of FLT3-ITD allelic ratio and insertion site, as well as cooperating genetic lesions on prognosis and treatment decision making in a large cohort of homogeneously treated younger adult patients.
The basis of the study were 2377 younger adults (median age, 48 years; range, 16–62 years) with newly diagnosed AML enrolled on three prospective treatment trials of the German-Austrian AML Study Group (AMLSG) between 1993 and 2008. Patients with acute promyelocytic leukemia (n=99), core-binding factor AML (n=279) and AML with adverse-risk cytogenetics (n=436) according to the European LeukemiaNet recommendations were excluded. Based on material availability, the presence of FLT3-ITD could be analyzed in 1414 patients; NPM1 and DNMT3A mutational status was available in 97% and 84% of the patients, respectively. In FLT3-ITD positive AML (n=394), the allelic ratio, determined by Genescan-based fragment-length analysis, was available in 86% and the insertion site in 72%. Allogeneic hematopoietic stem cell transplantation (HSCT) in first complete remission was performed in 41% and 29% of FLT3-ITD positive and negative patients, respectively.
We first evaluated the prognostic impact of the different FLT3-ITD characteristics within the subgroup of FLT3-ITD positive patients. The allelic ratio was categorized into quartiles ranging from low to high. For the endpoints event-free (EFS), relapse-free (RFS) and overall survival (OS), only the fourth quartile with the highest allelic ratio showed a prognostic impact for all endpoints, whereas no difference was identified between the other three quartiles. For further analyses, the allelic ratio was dichotomized comparing the fourth quartile versus the other three quartiles. FLT3-ITD insertion site in the beta1 sheet was significantly associated with an unfavorable outcome for all endpoints. Additionally, FLT3-ITD size was directly correlated with the insertion site: the more C-terminal the ITD inserted in the FLT3 gene the longer the FLT3-ITD size. There was no prognostic impact of FLT3-ITD size neither as continuous nor as quartile-categorized variable. Multiple FLT3-ITDs, present in 13% of AMLs, were associated with an unfavorable prognosis. The presence of either NPM1 and/or DNMT3A mutations in FLT3-ITD positive patients did not alter the original FLT3 prognosis. In multivariable models for the endpoint OS of the total cohort of intermediate-risk AML, an independent prognostic impact beyond the variable FLT3-ITD was shown for the allelic ratio (fourth quartile) HR, 1.4; p=0.037 and in trend for insertion site in the beta1 sheet HR, 1.33; p=0.06. Survival of patients exhibiting a high allelic ratio (n=43) or insertion site in the beta1 sheet (n=60) was comparable, with a median of 10 and 13 months and 4-year survival of 19% and 24%, respectively. Of note, outcome of patients with both high allelic ratio and insertion site in the beta1 sheet (n=21) was very poor with a median OS of 10 months and 4-year OS of 5%, respectively. In patients with FLT3-ITD positive AML without these unfavorable factors (n=144), median and 4-year OS were 15 months and 42%, respectively. Of note, a clear benefit of allogeneic HSCT in first CR was only seen in FLT3-ITD positive patients without these two unfavorable factors, with a 4-year OS of 63%. In comparison, the 4-year OS of the same subgroup of patients achieving a CR after induction therapy without proceeding to allogeneic HSCT during first CR was 35%. In contrast, outcome in patients with high allelic ratio and/or insertion site in the beta1 sheet remained poor despite allogeneic HSCT in first CR.
High FLT3-ITD allelic ratio and ITD insertion site in the beta1 sheet presented as prognostic indicators for poor outcome in patients with the presence of a FLT3-ITD. Only patients without these unfavorable FLT3-ITD features significantly benefitted from allogeneic HSCT.
Schlenk:Roche: Research Funding; Pfizer: Research Funding; Amgen: Research Funding.
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