Peripheral Blood Blast Clearance Research Articles

Early Peripheral Blood Blast Clearance As a Prognostic Marker for Early Treatment Response in Pediatric Acute Myeloid Leukemia

Background and Significance The cure rate of pediatric acute myeloid leukemia (AML) has improved significantly; however, relapses still occur in up to 30% of the total patient population in high-income countries (HICs), and in an even higher percentage of patients in low- and middle-income countries (LMICs). Early treatment response, cytogenetics and minimal residual disease (MRD) are well-known prognostic factors for treatment outcome; however, sophisticated techniques for identifying prognostic factors are often lacking in LMICs, and are sometimes unsuccessful in HICs. Early treatment response assessed by a bone marrow (BM) aspirate on day 15 or day 22 (D22) (depending on the applicable protocol) after initiation of chemotherapy is a known prognostic factor for outcome in patients with pediatric AML, but does not allow modifications of the first induction chemotherapy course (Creutzig 2014, Abrahamsson 2011, Kern 2003). In both pediatric acute lymphoid leukemia (ALL) and adult AML, early peripheral blood blast clearance (PBBC) is a known early indicator of treatment response (Manabe 2008, Arellano 2012), whereas to the best of our knowledge, this has not yet been reported in pediatric AML. In this study, we evaluated the significance of time to complete PBBC, and rate of PBBC after initiation of chemotherapy, in relation to disease status in BM D22, as measure of early treatment response that has prognostic significance. Study Design and Methods Pediatric patients with AML, aged 0-18 years, that were treated according to the NOPHO-DBH AML-2012 protocol were included. The first 5 days of induction therapy consisted of etoposide, followed by 7 days of low-dose cytarabine and mitoxantrone or liposomal daunorubicin. Peripheral blood (PB) was assessed by morphology at the time of diagnosis, daily in the first week, and thrice weekly until D22 or until occurrence of complete clearance of blasts. BM D22 was assessed by morphology and flow cytometry. A receiver operating characteristic (ROC) analysis was performed to evaluate the predictive power of days from starting chemotherapy to complete PBBC. The correlation between time to complete PBBC and BM D22 results was analyzed using a logistic regression model. Multivariable logistic regression models were applied for the association after adjusting for effects of other covariates. Rate of PBBC was defined as the percentage of the absolute PB blast count on the day of diagnosis that cleared with each day of therapy, on average, until D22 or the day of complete PBBC. Results In total, 319 patients were included, out of whom 241 were eligible for analysis, and 78 not eligible due to missing or incomplete data. Day 9 after initiation of chemotherapy was identified as the most discriminating cut-off point for predicting BM D22 response. Patients were categorized into early PBBC (≤9 days; n=159) and delayed PBBC (>9 days; n=82) groups. Early PBBC was associated with having <5% AML cells in BM D22 as assessed by both morphology (OR 3.11; P=0.005) and flow cytometry (OR 2.73; P=0.041). Early PBBC also showed a much lower likelihood of having >15% AML cells in BM D22 by morphology (OR 0.08; P=0.002). None of the early PBBC patients had >15% AML cells in BM D22 by flow cytometry. For 217 patients (selection due to missing data [n=24]), the rate of PBBC could be calculated, and a discriminative cut-off value of 11% was identified. Patients were categorized into high rate of PBBC (>11%; n=132) and low rate of PBBC (≤11%; n=85). High rate of PBBC was associated with having <5% AML cells in BM D22 by flow cytometry (OR 4.30; P=0.007) and negative MRD status (OR 2.02; P=0.004), while also showing a strong association with a lower likelihood of >15% AML cells in BM D22 (OR 0.11; P=0.007) by morphology. None of the high rate PBBC patients had >15% AML cells in BM D22 by flow cytometry. Conclusion Both early complete PBBC and rate of PBBC after initiation of chemotherapy holds promise as prognostic marker for clinical outcome in pediatric AML, as it correlates significantly with BM D22 response. These findings may offer an early and easily accessible prognostic factor, particularly beneficial for LMICs, as well as for patients with unsuccessful MRD analyses.

Phase 1 Dose Escalation Trial of Pegcrisantaspase in Combination with Venetoclax in Adults with Relapsed or Refractory Acute Myeloid Leukemia

Background: Acute myeloid leukemia (AML) cells are sensitive to depletion of extracellular glutamine (Gln) or manipulation of Gln metabolism. We recently reported the synergistic anti-leukemic activity of the combination of the Bcl-2 inhibitor Venetoclax (Ven) and pegcrisantaspase (PegC), a pegylated Erwinia asparaginase, in complex karyotype AML (CK-AML). The potent in vitro and in vivo activity of Ven-PegC regimen is mediated through inhibition of 4EBP1 phosphorylation resulting in decreased mRNA translation and protein synthesis. We hypothesized that safe and tolerable doses of Ven-PegC will result in anti-AML activity in patients (pts) with relapsed/refractory (R/R) AML. Study Design and Methods: The study is an open-label phase 1b clinical trial (NCT04666649) with 3+3 design with 4 cohorts of Ven (400 mg daily in the cohorts 1-3, 600 mg daily in cohort 4) in combination with outpatient intravenous PegC (500, 750, 1000, 1000 IU/m2 in cohorts 1-4, respectively) biweekly in a 28-day cycle. Key eligibility criteria include AML in an adult that has relapsed after, or is refractory to first-line therapy including Ven-containing regimens. The primary endpoints are the incidences of regimen limiting toxicities (RLT) and treatment emergent adverse events of Ven-PegC. Secondary endpoints include rate of composite complete remissions. Exploratory endpoints include the evaluation of plasma amino acid levels of Gln, asparagine (Asn), glutamate (Glu), and serine (Ser), and plasma asparaginase activity post-PegC administration. Results: As of August 1, 2022, 11 pts who received at least 1 dose of PegC were enrolled into the first two cohorts. The median age was 60 (range 24-76) years; 6 (55%) were female; 10 (91%) had adverse-risk AML by European Leukemia Net (ELN) criteria; 7 (64%) had CK-AML, and median prior treatments were 2. Overall response rate was 64% (7 pts) including 3 pts (27%) with CR/CRh/CRi [2 previously Ven-refractory]. In the first cohort, pt2 cleared peripheral blood (PB) blasts within 3 days after the first dose of PegC. Pt5 bone marrow (BM) blasts significantly decreased (78% to 9%) after cycle 1, and pt6 achieved CR with partial hematologic recovery (CRh) with MRD-negativity after 1 cycle and proceeded to alloHSCT after 3 cycles of Ven-PegC. In cohort 2, pt9 cleared PB blasts within 3 days after the first dose of PegC, and pt12 (primary refractory AML with two TP53 mutations) achieved a rapid clearance of PB blasts (41% to 0% after 2 days) and BM blasts after 1 dose of PegC and achieved MRD-negative CR at the end of cycle 1. Pt15 achieved CR with incomplete hematologic recovery (CRi) after 1 cycle of Ven-PegC and is currently receiving cycle 3, and in pt16 absolute PB blasts reduced from 4876/mcL to 192/mcL on Cycle 1 Day 3 and is currently receiving cycle 1 (Fig 1). Eight patients were evaluable for RLT assessment. No RLT was observed in cohort 1. In cohort 2, one transient (<48h) asymptomatic hypertriglyceridemia was observed and resulted in the expansion of cohort 2 to 6 patients. No serious asparaginase-related adverse events of interest have been observed. Pharmacokinetic and pharmacodynamic data are available for 8 patients. All pts achieved a nadir plasma asparaginase activity >0.1 IU/mL during cycle 1 and repetitive doses of PegC did not result in silent inactivation. Mean (range) plasma amino acid levels (µmol/L) at baseline were: Asn 31 (24-38), Gln 412 (323-465), Glu 58 (22-103). All pts achieved undetectable Asn level by day 7 and Asn remained undetectable throughout the study. Plasma Gln reduction from baseline occurred in all pts within cycle 1, with pts in cohort 2 demonstrating a more rapid decrease in Gln levels after initial exposure, confirming a dose-response correlation. Of note, in both cohorts, the pts that responded to Ven-PegC achieved the lowest absolute plasma Gln levels. A concomitant increase in plasma Glu levels was observed in all pts, indicative of the PegC-induced conversion of Gln to Glu. Remarkably, plasma Ser increased ~2-fold at the nadir of plasma Gln, from 75 ± 21 µmol/L at baseline to 114 ± 30 µmol/L after the first dose of PegC (Fig 2). Conclusion: Ven-PegC is a well-tolerated regimen with a novel metabolically-targeted mechanism of action. Early efficacy results in patients with poor prognosis R/R AML, a population with very limited treatment options, has been very promising. A clear correlation between the dose of PegC administered and the reduction in plasma Gln was observed. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Molecular Characterization of a First-in-Human Clinical Response to Nimesulide in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is a hematologic malignancy associated with high morbidity and mortality. Here we describe a case of a patient with AML who presented a partial response after utilization of the non-steroidal anti-inflammatory drug nimesulide. The response was characterized by complete clearance of peripheral blood blasts and an 82% decrease of bone marrow blasts associated with myeloblast differentiation. We have then shown that nimesulide induces in vitro cell death and cell cycle arrest in all AML cell lines (HL-60, THP-1, OCI-AML2, and OCI-AML3). Weighted Correlation Network Analysis (WGCNA) of serial whole-transcriptome data of cell lines treated with nimesulide revealed that the sets of genes upregulated after treatment with nimesulide were enriched for genes associated with autophagy and apoptosis, and on the other hand, the sets of downregulated genes were associated with cell cycle and RNA splicing. Serial transcriptome of bone marrow patient sample confirmed the upregulation of genes associated with autophagy after the response to nimesulide. Lastly, we demonstrated that nimesulide potentiates the cytotoxic in vitro effect of several Food and Drug Administration (FDA)-approved chemotherapy drugs used in AML, including cytarabine.

Relationship between Effect of Induction Chemotherapy and Prognosis in AML Patients

To explore the relationship between effect of induction chemotherapy and prognosis in acute myeloid leukemia (AML) patients. The clinical data of 146 adult AML patients treated in Affiliated Hospital of Chifeng University from March 2015 to March 2018 were enrolled and retrospectively analyzed. Day 14 bone marrow biopsy (D14BM) cellularity and blast proportion, daily peripheral blood blast (PBB) clearance rate, time to PBB clearance and etc. were primarily observed after induction chemotherapy. All the patients were divided into Non-relapse survival group, Relapse survival group, Non-relapse death group and Relapse death group according to survival and recurrence situation during 2-year follow-up. The survival of the patients was analyzed by Kaplan-Meier. Univariate analysis of prognostic factors were performed by ordinal Logistic regression, and ROC curve was used to assess the prediction efficiency of those factors for the 2-year overall survival (OS) and relapse of the patients. A total of 138 patients were included since 8 cases failed to be assessed clinically. Their 2-year OS rate was 65.94%. Age of the patients in Non-relapse survival group was lower than that in Relapse death group. The D14BM cellularities in Non-relapse survival group and Relapse survival group were lower than those in Relapse death group (P<0.05). Daily PBB clearance rates in Non-relapse survival group and Relapse survival group were higher than those in Non-relapse death group and Relapse death group (P<0.05). There was a statistical difference among the four groups in the number of cycles of induction chemotherapy (P<0.05). The survival rate within 2 years in the patients with D14BM cellularity≤10% was higher than that in patients with cellularity >10%, while it was higher in patients with daily PBB clearance rate >20% than those with clearance rate≤20% (P<0.05). Age (HR=1.102, P=0.000), D14BM cellularity (HR=1.252, P=0.000) and the cycles of induction chemotherapy≥3 (HR=1.703, P=0.000) were the risk factors affecting the prognosis of AML patients, while daily PBB clearance rate was a protective factor (HR=0.799, P=0.000). The AUC of age, daily PBB clearance rate and D14BM cellularity in predicting 2-year OS of AML patients was 0.738, 0.817 and 0.807, respectively, whereas in predicting relapse within 2 years it was 0.691, 0.647 and 0.711, respectively. There was no statistical difference among the three factors in the sensitivity of 2-year OS (68.11%, 85.12%, 74.49%) and 2-year relapse (50.00%, 64.13%, 61.60%) (P>0.05). Bone marrow biopsy results and PBB clearance rate are related to prognosis in AML patients, which can offer certain predictive value in assessing 2-year OS of patients.

The prognostic value of the peripheral blood cell counts changes during induction chemotherapy in Chinese patients with adult acute myeloid leukemia.

To investigate the prognostic value of the circulating peripheral blood cell counts changes in acute myeloid leukemia (AML) at different time points during induction chemotherapy.We retrospectively analyzed the clinical and laboratory data of 237 newly diagnosed AML patients admitted to Fujian Medical University Union Hospital from January 2011 to December 2014.1. When primitive cells were first removed from the circulating peripheral blood, it was called peripheral blood blast clearance (PBBC). These patients were divided into two groups, according to PBBC. Statistical analysis showed that the day 5 of induction chemotherapy was a better cut-off for PBBC. PBBC≤5 days is defined as early-blast-clearance, while PBBC >6 days is delayed-blast-clearance. There was significant difference between the two groups on complete remission (CR) rate (P = .002), recurrence-free survival (RFS) (P = .026) and overall survival (OS) (P = .001). 2. Multivariate analysis suggested PBBC is an independent prognostic factor for CR, RFS, and OS in AML. Receiver operating characteristic(ROC) curve analysis showed the CR rate of patients with white blood cell count less than 1.25 × 109/L was significantly higher than that of patients with white blood cell count more than 1.25 × 10 9/L (P < .001) at day 5 of induction chemotherapy, but the RFS and OS was no significantly different (P > .05).The dynamics of peripheral blood blast in AML after initiation of induction chemotherapy, especially the time length to achieve PBBC, has important prognostic value for CR rate, RFS, and OS in AML patients. It is a simple and feasible method to evaluate the efficacy of AML.

Peripheral blood blast rate of clearance is an independent predictor of clinical response and outcomes in acute myeloid leukaemia.

The day 14 bone marrow aspirate and biopsy (D14BM) is regularly used to predict achievement of complete remission (CR) with induction chemotherapy in acute myeloid leukemia (AML), however its utility has been questioned. Clearance of peripheral blood blasts (PBB) may serve as an early measure of chemosensitivity. PBB rate of clearance (PBB-RC) was calculated for treatment-naive AML patients (n=164) undergoing induction with an anthracycline and cytarabine (7+3) and with detectable PBB at diagnosis. PBB-RC was defined as the percentage of the absolute PBB count on the day of diagnosis that was cleared with each day of therapy, on average, until D14 or day of PBB clearance. Each 5% increase in PBB-RC approximately doubled the likelihood of D14BM clearance (OR=1·81; 95% CI: 1·24-2·64, P<0·005). PBB-RC was also associated with improved CR rates (OR per 5%=1·97; 95% CI: 1·27-3·01, P<0·005) and overall survival (OS) [hazard ratio (HR) per 5%=0·67; 95% CI: 0·52-0·87]. African American patients had poorer OS adjusted for PBB-RC (HR=2·18; 95% CI: 1·13-4·23), while race was not associated with D14BM or CR rate. PBB-RC during induction chemotherapy is predictive of D14BM clearance, CR, and OS, and can therefore serve as a prognostic marker for clinical outcomes in AML.

Peripheral Blood Blast Clearance As an Independent Predictor of Clinical Response and Outcomes in Acute Myeloid Leukemia

IntroductionAcute myeloid leukemia (AML) is a heterogeneous disease that depends on precise risk-stratification for predicting outcomes and optimizing therapy plans. Despite the current clinical landscape of incorporating karyotype and mutations into prognostic models, chemosensitivity (or lack thereof) is usually not evaluated or appreciated until a patient undergoes a day 14 bone marrow (D14BM) evaluation during induction treatment. While the D14BM aspirate and biopsy are regularly used to predict achievement of CR versus need for further reinduction therapy, some have questioned its utility. Further, the invasive nature of the procedure leads to significant patient discomfort, anxiety, increased risk of complications (infections, bleeding, damage to surrounding tissues) and, at times, is not feasible due to a patient's critical state. Therefore, alternative criteria are needed to help risk-stratify these patients and predict treatment responses. We report here a single center analysis of the relationship between the rate of peripheral blood blast (PBB) clearance with cytotoxic induction therapy and clinical outcomes.MethodsPatients diagnosed with AML (non-M3) with detectable PBB via manual differential or flow cytometry at University of Maryland Greenebaum Comprehensive Cancer Center (UMGCCC) during 2007-2018 were identified. Only patients who underwent induction with a “7+3” regimen with cytarabine and an anthracycline (idarubicin or daunorubicin), or “7+3” plus a third agent, were included. Patient and disease characteristics, treatment courses, and clinical outcomes were collected. The absolute PBB count was calculated by percent PBB multiplied by total leukocyte count (103/mcL). PBB rate of clearance (PBB-RC) was defined as the percentage of the absolute PBB count at diagnosis that was cleared each day, on average, until clearance or D14 of induction chemotherapy. Patients were divided into three groups based on PBB-RC: high, if PBB-RC >30% (n=15); low, if PBB-RC <10% (n=16); and intermediate, if PBB-RC fell between 10-30% (n=133). Primary outcomes included D14BM status, achievement of complete remission (CR) with or without full count recovery, and overall survival (OS). Multivariate logistic regression and Cox proportional hazards models were conducted and adjusted for the disease risk category, age, sex, ethnicity, and use of leukapheresis or hydroxyurea. Cox models were also adjusted for allogeneic stem cell transplantation (SCT) status.ResultsTreatment-naive AML patients with PBB at diagnosis and who underwent cytotoxic induction therapy were identified (n=164). Patient characteristics are shown in Table 1. Sixty-eight percent of patients underwent induction with “7+3”, and 28% with “7+3” with a third agent. Pre-induction leukoreduction included hydroxyurea (29%) and/or leukapheresis (12%). Most (68%) patients received only one course of induction; 18% received 2 courses, and 8% received ≥3. Chemoablation on D14BM was achieved in 70% of patients (n=113); 27% (n=45) had residual disease, and 4% (n=6) were indeterminate. CR was achieved in 74% of patients (n=121), 19 of which required ≥ 2 induction courses. Forty-one patients proceeded to SCT. Median OS was 18.5 months (range 0.5-122).Each 5% increase in PBB-RC approximately doubled the likelihood of D14BM clearance (OR=1.97; 95% CI: 1.39-2.80, p<0.001). The adjusted area under the ROC curve of PBB-RC for predicting D14BM clearance was 0.72, with a positive predictive value (PPV) of high PBB-RC of 93% and negative PV (NPV) of low PBB-RC of 81%. PBB-RC was also significantly associated with CR (OR per 5% =2.08; 95% CI: 1.38-3.14, p<0.001). CR was achieved in all patients in the high PBB-RC group, while only 44% in the low PBB-RC group. PBB-RC was significantly associated with improved OS (HR per 5%=0.67; 95% CI: 0.52-0.85, Figure 1). Other factors associated with longer OS included favorable risk category (HR=0.03; 95% CI: 0.01-0.23) and SCT (HR=0.50; 95% CI: 0.26-0.95). African American patients had poorer OS adjusted for PBB-RC (HR=2.22; 95% CI: 1.16-4.25), while race was not associated with D14BM or CR rate.ConclusionPBB-RC during induction chemotherapy is predictive of achievement of CR and improved OS in AML. PBB-RC is also significantly associated with D14BM clearance and can therefore serve as a surrogate predictive marker for treatment response in AML patients with PBB at diagnosis.. [Display omitted] DisclosuresEmadi:NewLink Genetics: Research Funding.

The Clinical and Biological Implications of Early Clearance of Peripheral Blood Blasts after Induction Chemotherapy in Acute Myeloid Leukemia

IntroductionAcute myeloid leukemia (AML) is a highly heterogeneous disease with various genetic abnormalities. Cytogenetics, gene mutations, gene expression profiles, and microRNA expressions affect prognosis in AML patients. Some of these exams are cumbersome and not readily available. In contrast, routine complete blood counting and morphological classification is a simple and real time method, and may be used for prediction of response to treatment. Rapid peripheral blood (PB) blasts clearance after induction chemotherapy has been shown to predict prognosis in AML patients, but those studies recruited small cohorts or lacked molecular correlations. In this study, we aimed to not only investigate the prognostic significance of this method in a large cohort but also extend its implications to genetic and biological levels.MethodA cohort of 333 de novo non-M3 AML patients who received standard chemotherapy at the National Taiwan University Hospital from 2003 to 2015 were included. The percentages of their PB blasts in the first week after initiation of induction chemotherapy were examined by morphological observation. Mutation analyses of 15 relevant molecular markers, including FLT3 (ITD and TKD), N-RAS, K-RAS, KIT, CEBPA, RUNX1, as well as NPM1, WT1, ASXL1, MLL/PTD, DNMT3A, IDH1, IDH2, and TET2, were performed in bone marrow mononuclear cells from 165 patients at diagnosis, who had available cryopreserved samples. We profiled whole-genome gene expression using Illumina HumanHT-12 v4 Expression BeadChip (Illumina, San Diego, CA) in 83 patients, who had enough mRNA for analyses. The difference in clinical features, cytogenetics, gene mutations, gene expression profiles, and treatment outcomes between patients who had PB blasts clearance within 7 days and those who failed were analyzed.ResultsAmong the 333 patients, 154 (46.2%) patients achieved clearance of PB blasts within 7 days of starting induction chemotherapy. There was no difference in gender, age, and hemograms at diagnosis between the two groups. The patients failed to clear PB blasts within one week had higher incidence of FAB M0 (5.6% vs. 0.6%, p=0.012), higher percentage of 2017 European LeukemiaNet (ELN) adverse-risk category (40.8% vs. 26.0%, p=0.004), and lower incidence of mutated NPM1 (10.6% vs. 22.5%, p=0.039), FLT3-ITD (11.8% vs. 26.6%, p=0.015), and biallelic mutated CEBPA (9.8% vs. 24.1%, p=0.015) than those who cleared the PB blasts in 7 days. Failure to clear PB blasts within 7 days was a significant unfavorable risk factor for overall survival (OS) [5-year survival rate 53.3% vs. 76.0%, p=0.004 (figure 1)], and relapse-free survival (RFS) [median RFS 6.6 months vs. 18.6 month, p<0.001 (figure 2)]. We then combined age, white blood cell count at diagnosis, ELN risk category, and clearance of PB blasts within 7 days as co-variables for a Cox regression proportional hazard model and found that failure to achieve clearance of PB blasts independently predicted shorter OS and RFS [HR=1.699, 95% CI 1.065-2.711, p=0.026 (table 1), and HR=1.896, 95% CI 1.398-2.573, p<0.001 respectively].We profiled the global mRNA expression to explore the possible underlying molecular pathways which distinguish these two groups of patients. We identified 192 unique genes with differential expression (> 1.5 fold change, t-test p < 0.05). Gene-annotation enrichment analysis using DAVID 6.8 revealed that these differentially expressed genes were associated with abundant biological functions in a variety of categories. Among them were genes that were associated with cell proliferation (p = 9.68 × 10−4), and apoptosis (p = 3.08 × 10−3). Gene Set Enrichment Analysis (GSEA) revealed significant enrichment in “genes up-regulated in hematopoietic stem cells compared to hematopoietic progenitor cells” (empirical p<0.001) and “predominant long-term growth and self-renewal phenotype” (empirical p<0.001) in the patients with failure to clear PB blasts within 7 days.ConclusionThis study demonstrated that rapid clearance of PB blasts is an independent favorable prognostic factor irrespective of age, WBC and 2017 ELN risk classification, and would be a simple and real time tool to predict the patients' prognosis. This parameter separates the patients into groups with distinctive clinical and biological features. Further prospective and larger cohorts are needed to confirm our observations. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Pilot Study of Combined Type I FLT3 Tyrosine Kinase Inhibitor, Crenolanib with Sorafenib in Pediatric Patients with Relapsed/Refractory FLT3+Ve AML

Background: Crenolanib is a novel type I pan-FLT3 inhibitor, which inhibits both FLT3-ITD, as well as FLT3 tyrosine kinase domain (TKD) activating mutations. Combination of crenolanib (Type I) and sorafenib (Type II) has been shown to have synergistic apoptotic effects in FLT3+ve AML blasts derived from patients (pts) who have relapsed after prior sorafenib treatment. We hypothesized that the combination of crenolanib and sorafenib may provide enhanced FLT3 inhibition by targeting both inactive as well as active FLT3 kinase conformations. We here report the results of a dose finding study of sorafenib given with fixed doses of crenolanib in pediatric pts with FLT3+ve AML.Design: This pilot study was designed to assess the tolerability of escalating doses of sorafenib with full doses of crenolanib (66.7 mg/m2 TID) in pediatric pts with relapsed or refractory FLT3+ve AML. Crenolanib was administered continuously at 66.7 mg/m2 TID starting on d1. Sorafenib was administered continuously starting from d8 at 150 mg/m2/d (dose level 1). The rolling-6 design was used and if no DLTs were seen, sorafenib was escalated to 200 mg/m2/d (dose level 2). Additionally, triple intrathecal therapy with methotrexate, hydrocortisone, and cytarabine was given on d8 and continued weekly in pts with CNS leukemia until CSF was free of blasts.Results: From April 2015 to March 2016, 7 children (median age, 9yrs; range, 5-14yrs) have been enrolled. All pts had progressed after a median of 3 prior AML therapies (range, 1-7). Four pts had progressed after frontline treatment, which included sorafenib maintenance; the other 3 pts had progressed after standard chemotherapy. Two pts had undergone prior allo SCT. Median WBC count prior to therapy was 1.7 x 109/L (range 0.7-7.5 x 109/L) with median blast percentage of 15% (range 0-60%). All 7 pts had a FLT3-ITD (mutant to wild-type FLT3 ratio ranged from 0.048 to 22, with one pt not having any wild type FLT3 allele). At the time of study entry, 2 pts had active CNS leukemia and required additional intrathecal therapy.Crenolanib 66.7 mg/m2 TID was well tolerated with no pt requiring crenolanib dose reduction. Sorafenib was administered to the first 3 pts at 150 mg/m2 QD from d8 onward. As no DLTs were observed at 150 mg/m2 QD dose, sorafenib was dose escalated to 200 mg/m2 QD for the next 4 pts. No DLTs were observed at either of the sorafenib doses. The combination of crenolanib/sorafenib was well tolerated with most AEs being grade 1 and 2 in severity. Rash was frequently seen in pts following the addition of sorafenib and one pt developed grade 2 hand-foot syndrome which resolved within 5d on the same dosing regimen. No grade 4 LFT elevations were seen in any pt.During cycle 1 of therapy, crenolanib/sorafenib combination resulted in clearance of peripheral blood blasts in 5/6 pts and 1 pt without blasts at baseline had resolution of extramedullary neck mass. Reduction of bone marrow blasts was seen in 4/7 pts. By Cheson criteria, one patient achieved a CR (with FLT3 negativity), two had a PR, and one had a marrow response of CRi but with persistent CNS disease. Three pts had NR although 2 had transient benefit from crenolanib on day 8 as determined by BM blast percentage. Peripheral blood and bone marrow blast percentages are summarized in Figure 1 and Table 1, respectively. Median overall survival was 221d (Figure 2) with 2 pts currently still alive.Conclusions: Crenolanib 66.7 mg/m2 TID can be safely combined with sorafenib at 200 mg/m2 QD. Even in pts with prior exposure to sorafenib, this combination showed clinical benefits, represented by rapid reduction of bone marrow or peripheral blasts, and was able to have improved quality of life. Although dual TKI combinations targeting the same receptor have not been tried in AML, such strategies have been shown to have efficacy in other diseases like HER2+ve breast cancer. Pharmacokinetics of crenolanib and sorafenib and FLT3-TKD mutation analysis will be presented. Accrual to this trial continues. [Display omitted] [Display omitted] [Display omitted] DisclosuresInaba:Arog: Research Funding. Eckardt:Arog: Employment, Equity Ownership.

Peripheral blood blast clearance is an independent prognostic factor for survival and response to acute myeloid leukemia induction chemotherapy.

In patients with acute myeloid leukemia (AML), rapid reduction of circulating blasts with induction chemotherapy may serve as an in vivo marker of chemosensitivity. We performed a retrospective analysis of 363 patients with untreated AML who received induction chemotherapy in order to determine the relationship between day of blast disappearance (DOBD) and complete remission (CR) rates, event-free survival (EFS), and overall survival (OS). DOBD ≤ 5 vs. >5 was identified as the most discriminating cutoff for OS. DOBD > 5 was observed in 35 patients (9.6%). The CR rate for patients with DOBD ≤ 5 vs. >5 was 74.0 and 28.6%, median EFS was 9.4 and 1.8 months, and median OS was 17.1 and 5.8 months, respectively (P < 0.001 for all). DOBD > 5 was independently associated with a lower CR rate and shorter EFS and OS (P < 0.001 for all). DOBD > 5 retained prognostic significance for EFS and OS when patients were stratified by cytogenetic risk group, de novo vs. secondary or therapy-related AML, European LeukemiaNet-based risk groups, and whether CR was achieved. We propose DOBD > 5 as a simple and early marker of disease resistance that identifies patients with poor prognosis who otherwise may not be identified with existing risk stratification systems. Am. J. Hematol. 91:1221-1226, 2016. © 2016 Wiley Periodicals, Inc.

The Time to Clearance of Peripheral Blood Blasts Predicts Complete Remission and Survival in Chinese Adults with Acute Myeloid Leukemia

The value of clearance of peripheral blood blasts (PBB) as a predictor of outcomes in acute myeloid leukemia (AML) is controversial. To investigate the prognostic significance of the time to clearance of PBB after induction in Chinese patients with AML, a retrospective analysis of 146 patients with newly diagnosed AML at Shanghai Ruijin Hospital was performed. Patients were categorized into early blast clearance (EBC; ≤5 days) and delayed blast clearance (DBC; >5 days) groups based on a receiver operating characteristic analysis. Complete remission (CR) after induction chemotherapy was related to the time to clearance of PBB (p < 0.001). Relapse-free survival (RFS; p = 0.003) and overall survival (p < 0.001) were longer in the EBC group. Multivariate analysis demonstrated that the time to clearance of PBB and cytogenetic risk independently predicted CR and RFS. Early clearance of PBB after induction chemotherapy can be a significant predictor of survival outcomes in AML patients.

Routine interim disease assessment in patients undergoing induction chemotherapy for acute myeloid leukemia: Can we do better?

The presence of >5% blasts at "day 14" (D14), in patients undergoing induction chemotherapy for acute myeloid leukemia (AML) is problematic. It is unclear if a second course of chemotherapy for early persistent disease will alter outcome in these patients. We conducted a retrospective study of AML patients undergoing induction chemotherapy where diagnostic, interim (around day 14), and recovery (days 21-42) bone marrow (BM) evaluations were available for review. Of the 113 patients included in the final analysis, 99 (87.6%) achieved CR at hematologic recovery. At D14, 90 patients (79.6%) had <5% blasts and of these, 87 (96.7%) ultimately achieved CR. At D14, Twenty-three (20.4%) patients had residual leukemia (>5% blasts). Of these, 11 (47.8%) received a second course of chemotherapy (double induction [DI]) and 12 (52.2%) were observed until count recovery (single induction [SI]). No significant difference in CR rates was observed between these two groups (58.3% DI group vs. 45.5% SI group, P value = 0.684). In our analysis, D14 BM evaluation did not uniformly identify patients with primary induction failure. To unequivocally determine the value of a D14 marrow assessment in AML, prospective studies in the context of large cooperative group trials are required. Considering our findings and similar reports from others, we propose that D14 marrow assessment should be individualized, and that other factors, such as cytogenetics and early peripheral blood blast clearance should be considered, to identify patients most likely to benefit from interim disease assessment during AML induction therapy.

The prognostic significance of rapid peripheral blood blast clearance during the initial course of induction chemotherapy in young patients withde novoacute myeloid leukemia

The early clearance of blast cells in peripheral blood (PB) during induction chemotherapy can predict the clinical outcome in acute leukemia. We retrospectively analyzed the kinetics of white blood cell (WBC) count, blast cell percentage (BCP), and blast cell count (BCC) in PB in 78 patients with de novo acute myeloid leukemia who underwent a uniform induction chemotherapy between December 2001 and December 2015 at Jichi Medical University. By a repeated-measures analysis of variance, the interaction of the decline in BCP with the achievement of complete remission (CR) was stronger than those of the decline in WBC or BCC. A receiver operating characteristic curve analysis for the achievement of CR showed that the areas under the curve for the decline in WBC, BCP, and BCC were 0.592, 0.703, and 0.634, respectively, and a decline in BCP of 9.25%/day within 4 or 5 days from induction chemotherapy was the optimal cutoff value. A multivariate analysis showed that a rapid decline in BCP (≥9.25%/day) was a significant predictive factor for CR, independent of the cytogenetic risk (p = 0.0096). A rapid decline in BCP during the first 5 days of induction chemotherapy may be a good predictor of CR. Copyright © 2015 John Wiley & Sons, Ltd.

Clinical significance of day 5 peripheral blast clearance rate in the evaluation of early treatment response and prognosis of patients with acute myeloid leukemia.

BackgroundMinimal residual disease detection in the bone marrow is usually performed in patients with acute myeloid leukemia undergoing one course of induction chemotherapy. To optimize the chemotherapy strategies, more practical and sensitive markers are needed to monitor the early treatment response during induction. For instance, peripheral blood (PB) blast clearance rate may be considered as such a monitoring marker.MethodsPB blasts were monitored through multiparameter flow cytometry (MFC). Absolute counts were determined before treatment (D0) and at specified time points of induction chemotherapy (D3, D5, D7, and D9). The cut-off value of D5 peripheral blast clearance rate (D5-PBCR) was defined through receiver operating characteristic (ROC) analysis. Prognostic effects were compared among different patient groups according to D5-PBCR cut-off value.ResultsD5-PBCR cut-off value was determined as 99.55%. Prognostic analysis showed that patients with D5-PBCR ≥99.55% more likely achieved complete remission (94.6% vs. 56.1%, P < 0.001) and maintained a relapse-free status than other patients (80.56% vs. 57.14%, P = 0.027). Survival analysis revealed that relapse-free survival (RFS) and overall survival (OS) were longer in patients with D5-PBCR ≥99.55% than in other patients (two-year OS: 71.0% vs. 38.7%, P = 0.011; two-year RFS: 69.4% vs. 30.7%, P = 0.026). In cytogenetic-molecular intermediate-risk group, a subgroup with worse outcome could be distinguished on the basis of D5-PBCR (<99.55%; OS: P = 0.033, RFS: P = 0.086).ConclusionsAn effective evaluation method of early treatment response was established by monitoring PB blasts through MFC. D5-PBCR cut-off value (99.55%) can be a reliable reference to predict treatment response and outcome in early stages of chemotherapy. The proposed marker may be used in induction regimen modification and help optimize cytogenetic-molecular prognostic risk stratification.Electronic supplementary materialThe online version of this article (doi:10.1186/s13045-015-0145-1) contains supplementary material, which is available to authorized users.

Early Peripheral Blood Blast Clearance: A New Chemosensitivity Indicator for Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a highly heterogeneous disease, and cytogenetics and molecular markers play important roles in the diagnosis, treatment, and prognosis of AML. Although cytogenetic karyotypes and molecular mutations are powerful prognostic predictors for outcome of AML patients, indicators of response to initiation chemotherapy have not been identified. In childhood acute lymphoblastic leukemia, a rapid decline of circulating leukemic blasts in response to induction chemotherapy or prednisone is one of the most important prognostic factors, not only for achieving remission but also for long-term survival [1]. Similarly, in patients with AML who have received induction chemotherapy, a rapid decrease in peripheral blood blasts (PBB) is also considered as a favorable indicator of response to chemotherapy [1-4] Citation: Su Long (2014) Early Peripheral Blood Blast Clearance: a New Chemosensitivity Indicator for Acute Myeloid Leukemia. SAJ Cancer Sci 1: 103. doi: 10.18875/2375-6683.1.103

The percentage of peripheral blood blasts on day 7 of induction chemotherapy predicts response to therapy and survival in patients with acute myeloid leukemia

Background Rapid clearance of peripheral blood blasts (PBBs) predicts complete remission (CR) and survival in patients with acute myeloid leukemia (AML). We aimed to explore the correlation between induction therapy response, outcome, and the PBB percentage. Methods Forty-six consecutive patients with de novo AML (excluding acute promyelocytic leukemia) were enrolled in this study. Flow cytometry was performed to identify cells with a leukemia-associated aberrant immunophenotype in the initial bone marrow aspirate and in peripheral blood on day 7 of induction therapy. Results The PBB percentage on day 7 (D7PBBP) was significantly lower in patients who achieved CR (0.03% (0.0%, 0.45%)) than in those who did not (10.85% (1.13%, 19.38%); u =-3.92, P &lt;0.001). The CR rate was significantly higher among patients with a D7PBBP of &lt;0.945% (84.62%, 22/26) than among those with a D7PBBP of ≥0.945% (25.0%, 5/20; χ 2 = 16.571, P &lt;0.001). D7PBBP was significantly correlated with overall survival (OS; r=-0.437, P=0.003) and relapse-free survival (RFS; r=-0.388, P=0.007). OS and RFS were significantly higher in patients with a D7PBBP of &lt;0.43% than in those with a D7PBBP of ≥0.43% (P &lt;0.001 and P=0.039, respectively). D7PBBP was also found to be an independent prognostic indicator in multivariate analysis for both OS (P=0.036) and RFS (P=0.035). Conclusion D7PBBP may be an important risk factor for the achievement of complete remission, for overall survival, and for relapse-free survival.

Rapid rate of peripheral blood blast clearance accurately predicts complete remission in acute myeloid leukemia

Rapid rate of peripheral blood blast clearance accurately predicts complete remission in acute myeloid leukemia

Dynamics and Prognostic Impact of Peripheral Blood Blast Clearance in Patients with Acute Myeloid Leukemia (AML) Receiving FLT3 Inhibitor Therapy in Combination with Induction Chemotherapy

Abstract 1417 Background:We have previously shown that for patients with acute myeloid leukemia (AML) treated with induction chemotherapy with cytarabine (ara-C) plus an anthracycline, the day of blast clearance from peripheral blood (PB) is a powerful prognostic marker. Earlier PB blast (but not white blood cell [WBC]) clearance portends improved overall survival (OS). We expanded our investigation to include patients with AML undergoing induction chemotherapy with ara-C (1.5g/m2 ×3 days) plus idarubicin (12mg/m2×3 days) that is, the AI regimen, plus sorafenib (400mg orally twice daily). Patients and Methods:We reviewed the clearance of PB blast and WBC (PB blasts = 0%, WBC≤0.1×109/dL), for patients with AML (except APL) undergoing AI alone (n=168) or AI+sorafenib (n=75). Patient characteristics for the AI alone group (n=168) were as follows: median age 55 years (range, 19–72), diploid cytogenetics (n=57, 34%), poor cytogenetics (n=61, 36%), FLT3-ITD positive (n=15, 9%), FLT3-negative (n=122, 73%), median WBC 5.0×109/dL (range, 0.3–132.3), median platelets 37×109/dL (range, 1–581), median hemoglobin 9.1g/dL (range, 4.0–13.2), median PB blasts 15% (range, 1–96), median BM blasts 42% (range, 1–96). Patient characteristics for the AI+sorafenib group (n=75) were as follows: median age 52 years (range, 18–66), diploid cytogenetics (n=38, 51%), poor cytogenetics (n=10, 13%), FLT3-ITD (n=25, 33%), FLT3-negative (n=48, 64%) median WBC 5.9×109/dL (range, 0.6–228.5), median platelets 51×109/dL (range 7–306), median hemoglobin 9.2g/dL (range, 7.4–12.6), median PB blasts 21% (range 0–98), median BM blasts 56% (range 6–98). Results:The overall response rate (ORR=CR+CRp) in the AI group was 63% (58%+5%) and 50 patients (30%) were resistant to therapy. The ORR in the AI+sorafenib group was 79% (72%+7%) and 11 patients (15%) were resistant. We analyzed OS by dividing patients based on the day of PB blast clearance: group 1 (0–1 days), 2 (2–3 days), 3 (4–5 days), 4 (6–8 days), and 5 (>8 days). For the patients receiving AI induction therapy, a total of 32, 59, 38, 18, and 2 patients were included in groups 1–5, and median OS for groups 1–4 were 167, 48, 67, and 25 weeks respectively. A logrank test comparison revealed these four OS curves were significantly different (p-value=0.0015). For the AI treatment group, earlier blast disappearance corresponded with better OS. In contrast, for patients in the AI+sorafenib group, the correlation between day of PB blast clearance and OS was less clear. A total of 10, 23, 25, 6, and 3 patients were included in groups 1–5. The median OS for groups 1, 3, and 4 were 101, 74, and 66 weeks respectively, and the median survival for group 2 could not be estimated because the curve did not fall below 0.5. The difference between these four survival curves was not significantly different (p-value=0.35). Survival differences for the AI group were more clearly demarcated when patients were divided based on blast disappearance within 0–5 days or >5 days (p-value=0.0004). A similar analysis in the AI+sorafenib group revealed no significantly different OS (p-value=0.13). Among patients in the AI+sorafenib treatment group, the mean day of blast disappearance for FLT3-ITD versus FLT3-negative patients was 5.2 vs. 4.5 days, and this difference was not statistically significant (p-value=0.33). While FLT3-ITD patients who cleared their blasts within 0–3 days (n=10) tended to have better OS survival than FLT3-ITD patients who cleared their blasts after 3 days (n=13), the difference in OS curves did not reach significance (p-value=0.18). Conclusion:The day of PB blast clearance is prognostic among patients receiving classic induction chemotherapy, where early clearance predicts better long-term outcomes. The addition of a targeted agent to a standard induction regimen limits the prognostic power of early PB blast clearance. We are currently investigating a novel mathematical approach to evaluate the prognostic value of clearance of peripheral blasts compared to WBC after initiation of therapy in patients receiving targeted agents during induction therapy; the approach aims to integrate the prognostic impact of FLT3 and NPM1 in combination with cytoreduction kinetics to better identify prognostically distinct groups. Disclosures:Off Label Use: Plerixafor plus G-CSF as a part of conditioning in allogenic transplant for AML/MDS.

Rapid Rate of Peripheral Blood Blast Clearance Accurately Predicts Complete Remission in Acute Myeloid Leukemia

AbstractAbstract 3551 Background:With intensive chemotherapy, many acute myeloid leukemia (AML) patients will enter complete remission (CR). Empirically, the bone marrow is typically examined 14 days after initiating induction therapy, and re-treatment is commonly considered if significant residual blasts remain. However, many patients receiving single induction will enter CR without additional therapy despite substantial amounts or residual marrow blasts on day 14, leaving considerable uncertainty about the value of early marrow assessments. An emerging alternative approach to predict the efficacy of induction therapy includes the assessment of peripheral blood blast (PBB) dynamics. Rapid clearance of PBB, determined either by review of manual differential counts or flow cytometry is predictive of CR (likelihood of 76–90%) and overall survival. We investigated whether mathematical modeling of early PBB dynamics using automated complete blood cell (CBC) counts and the manual differential could further refine our ability to predict CR. Patients and Methods:We identified 111 adult patients with circulating PBB who underwent curative-intent, single-cycle induction chemotherapy for newly diagnosed AML between April 1999 and December 2011. Therapy regimens included “7+3”-like (56.8%), and regimens of similar/higher (29.7%) or lower (13.5%) intensity. PBBs were quantified as WBC count from the automated CBC times percentage of blasts by manual differential (100 cells). Cytogenetic abnormalities, NPM1/Flt3 status, day 14 and recovery bone marrow data were extracted from patient records. In the 62 patients with >3 measurable PBB counts, the rate of PBB clearance was calculated by fitting an exponential decay curve to the data points of absolute PBB counts, starting on day 1 of chemotherapy. This subgroup of patients had similar baseline parameters as the whole group, including age, WBC count at diagnosis, cytogenetic risk, percent of secondary AML, therapy regimens were similar, and CR rates were identical (69 vs. 68%). Results:An exponential decay curve [N(t) = N0×e-xt, with x=decay constant] resulted in an excellent goodness of fit of early PBB dynamics (mean r2=0.93). Rapid PBB clearance was highly predictive of CR achievement, with an optimal cut-off of x=1.4 (corresponding to a 4.2-log reduction in tumor burden if maintained over the course of a weeklong chemotherapy) based on the receiver operating characteristic (ROC) curve. All but 1 of the 27 patients with x>1.4 achieved CR (positive predictive value [PPV]=96%) the only non-responder with x>1.4 had a combination of negative prognostic factors including secondary AML, unfavorable cytogenetics, older age, and lower intensity treatment. PPV of PBB clearance rate of 96% for predicting CR compared favorably to alternative previously published approaches such as day of PBB clearance or percentage of day 14 bone marrow blasts (84 and 85% respectively in our study). Day 14 marrow assessments did not add prognostic information in 26/27 patients who had fast PBB clearance rate (x>1.4). In univariate analyses, CR achievement was significantly correlated with a higher PBB clearance rate, younger age, primary AML, more favorable cytogenetics, and treatment intensity. In multivariate analyses including age, primary vs. secondary AML, cytogenetics, type of therapy, and PBB clearance rate (57 patients), only the PBB clearance rate remained statistically significantly associated with CR achievement. Importantly, information from CBC differentials is routinely available in most institutions and associated costs are low. Unlike determination of the exact day of PBB clearance that coincides with profound cytopenia, the PBB clearance rate is measured while PBB are still abundant, rendering the latter method less prone to sampling and observer errors. Conclusion:our findings suggest that early marrow assessment may not be necessary in AML patients who experience rapid PBB clearance upon induction treatment initiation as they have an almost 100% chance of achieving CR. Disclosures:Vainstein:Neumedicines Inc: Employment.

Predicting Duration of Neutropenia After Successful Intensive Induction Chemotherapy for Acute Myeloid Leukemia or High-Grade Myelodysplastic Syndromes

Abstract 4336 Background:Chemotherapy-induced neutropenia (CIN) is a major cause of morbidity and mortality in patients with acute myeloid leukemia (AML) or myelodysplastic syndromes (MDS) due to the risk of overwhelming infection. Although the risk for infections increases with longer duration of neutropenia, no attempts have been undertaken to predict time of neutrophil recovery in AML/MDS patients following intensive chemotherapy. In unpublished work, we have successfully used mathematical modeling of peripheral blood blast kinetics following induction chemotherapy to accurately predict the likelihood of subsequent complete remission (CR). In this retrospective study, we investigated whether data derived from mathematical modeling of early peripheral blood neutrophil or blast dynamics could predict the duration of CIN in AML/MDS patients undergoing intensive induction chemotherapy. Patients and Methods:We retrospectively analyzed a cohort of 59 consecutive patients with newly diagnosed AML or MDS who achieved CR after induction chemotherapy after 1 course of chemotherapy with a 7 + 3-like regimen. Daily peripheral blood neutrophil and blast counts were recorded from the initiation of chemotherapy until the day of neutrophil recovery (defined as an absolute neutrophil count [ANC] ≥ 500 cells/μL). In patients with ≥ 3 measurable neutrophil or blast counts within the first five days of data collection, the rate of peripheral blood neutrophil and blast clearance was calculated by fitting an exponential decay curve to the data points starting on day 1 of chemotherapy. Results:The average age of the study cohort was 54 years (range 25 to 78). Seventy-six percent had primary AML. Cytogenetic risk was favorable in 32%, intermediate in 37%, and adverse in 27% of patients. The 23 patients with initial ANC < 500 cells/μL had a significantly longer duration of neutropenia than the 36 patients with initial ANC ≥ 500 cells/μL (mean: 29 versus 26 days, range: 21 – 39 versus 21 – 34, p=0.045). Neither age nor percentage of blasts in the bone marrow at diagnosis predicted neutropenia duration. In patients for whom decay rates could be modeled, there was no association between duration of neutropenia and decay rate for neutrophils (n = 36) or blasts (n = 20). There was also no association with the day that neutrophils first started to decline (defined as the first drop < 70% of the initial neutrophil count) or the first day of blast clearance from peripheral blood. Seven patients received granulocyte colony-stimulating factor (G-CSF; 1 prior to chemotherapy for antecedent myelodysplastic syndrome and 6 between days 15 and 43 for prolonged neutropenia and/or febrile neutropenia); the duration of neutropenia in this group did not differ significantly from that of the cohort as a whole. Conclusion:While kinetics of normal blood counts following initiation of intensive chemotherapy do not appear helpful to predict the duration of subsequent neutropenia, pre-treatment ANC levels provide limited information, with patients who are severely neutropenic prior to induction chemotherapy for AML having a longer average duration of CIN. This observation may provide some clinical guidance on the risk-adapted use of G-CSF in patients with AML/MDS undergoing induction chemotherapy. Disclosures:Vainstein:Neumedicines Inc: Employment.