Re-induction therapy decisions based on day 14 bone marrow biopsy in acute myeloid leukemia

Literature review and expert opinion on the treatment of high-risk acute myeloid leukemia in patients who are eligible for intensive chemotherapy

In patients with Acute Myeloid Leukemia (AML), the assessment of disease risk plays a central role in the era of personalized medicine. Indeed, integrating baseline clinical and biological features on a case-by-case basis is not only essential to select which treatment would likely result in a higher probability of achieving complete remission, but also to dynamically customize any subsequent therapeutic intervention. For young high-risk patients with low comorbidities burden and in good general conditions (also called "fit" patients), intensive chemotherapy followed by allogeneic stem cell transplantation still represents the backbone of any therapeutic program. However, with the approval of novel promising agents in both the induction/consolidation and the maintenance setting, the algorithms for the management of AML patients considered eligible for intensive chemotherapy are in constant evolution. In this view, we selected burning issues regarding the identification and management of high-risk AML, aiming to provide practical advice to facilitate their daily clinical management in patients considered eligible for intensive chemotherapy.

Acute Myeloid Leukemia Presenting as Common Colds: An Uncommon Consideration

Acute myeloid leukemia is the most common form of leukemia and can present with a wide variety of signs and symptoms. This article presents a case of a middle-aged male who presented with ongoing upper respiratory cold-like symptoms and was then found to be severely pancytopenic. A diagnosis of acute myeloid leukemia was made after a bone marrow biopsy, and the patient underwent induction chemotherapy. This article brings to light the uncommon diagnosis of acute myeloid leukemia, from a common presentation, a common cold. Additionally, it discusses the initial workup and diagnostic process of acute myeloid leukemia, risk stratification, and a basic treatment algorithm.

Modelling acute myeloid leukemia (AML): What's new? A transition from the classical to the modern

Acute myeloid leukemia (AML) is a heterogeneous malignancy affecting myeloid cells in the bone marrow (BM) but can spread giving rise to impaired hematopoiesis. AML incidence increases with age and is associated with poor prognostic outcomes. There has been a disconnect between the success of novel drug compounds observed in preclinical studies of hematological malignancy and less than exceptional therapeutic responses in clinical trials. This review aims to provide a state-of-the-art overview on the different preclinical models of AML available to expand insights into disease pathology and as preclinical screening tools. Deciphering the complex physiological and pathological processes and developing predictive preclinical models are key to understanding disease progression and fundamental in the development and testing of new effective drug treatments. Standard scaffold-free suspension models fail to recapitulate the complex environment where AML occurs. To this end, we review advances in scaffold/matrix-based 3D models and outline the most recent advances in on-chip technology. We also provide an overview of clinically relevant animal models and review the expanding use of patient-derived samples, which offer the prospect to create more "patient specific" screening tools either in the guise of 3D matrix models, microphysiological "organ-on-chip" tools or xenograft models and discuss representative examples.

Advances in acute myeloid leukemia

Acute myeloid leukemia (AML) is an uncommon but potentially catastrophic diagnosis with historically high mortality rates. The standard of care treatment remained unchanged for decades; however, recent discoveries of molecular drivers of leukemogenesis and disease progression have led to novel therapies for AML. Ongoing research and clinical trials are actively seeking to personalize therapy by identifying molecular targets, discovering patient specific and disease specific risk factors, and identifying effective combinations of modalities and drugs. This review focuses on important updates in diagnostic and disease classifications that reflect new understanding of the biology of AML, its mutational heterogeneity, some important genetic and environmental risk factors, and new treatment options including cytotoxic chemotherapy, novel targeted agents, and cellular therapies.

Day 14 Bone Marrow Evaluation During Acute Myeloid Leukemia Induction in a Real-world Canadian Cohort

INTRODUCTION

The 2017 National Comprehensive Cancer Network guidelines for acute myeloid leukemia have recommended performing bone marrow (BM) aspiration and BM trephine biopsy (BMTB) 14 to 21 days after starting induction therapy (commonly referred to as "day 14 [D14] marrow"). Those who do not achieve a hypoplastic marrow, with cellularity < 20% and blasts < 5%, are recommended to undergo 2-cycle induction (2CI). We performed a retrospective analysis to determine the impact of D14 BM characteristics in predicting for remission, association with overall survival (OS), and the effect of 2CI according to the D14 BM results.

PATIENTS AND METHODS

Patients aged 18 to 70 years undergoing induction therapy with standard "7 + 3" regimens were included. D14 cellularity was determined from BMTB samples and the blast percentage was assessed by morphology on BM aspiration and BMTB samples. The outcomes evaluated included the rates of complete remission (CR) and OS.

RESULTS

A total of 486 patients with results from D14 BM evaluation were included in the present study. On multivariate analysis, cytogenetic risk and D14 blasts < 5% were predictive of CR/CR with incomplete count recovery (P < .001). Cytogenetic risk (P < .001), age < 60 years (P = .001), and D14 blasts < 5% (P = .045) predicted for OS. 2CI was performed in 131 patients (27%). Patients with hypocellular D14 BM but residual blasts (n = 106) underwent 2CI in 46% of cases, with improved remission rates (43.9% vs. 72.0%; P = .004) but no difference in OS.

CONCLUSIONS

The results from D14 BM evaluations are predictive of subsequent remission and OS. Our findings did not show a survival benefit with D14 BM-driven 2CI.

Observation Versus Immediate Reinduction for Acute Myeloid Leukemia Patients With Indeterminate Day 14 Bone Marrow Results

INTRODUCTION

The benefit of immediate reinduction chemotherapy for patients with indeterminate day 14 bone marrow results (≤ 20% cellularity and 5%-20% blasts) remains unclear. We report our experience with patients with acute myeloid leukemia (AML) with indeterminate day 14 bone marrow biopsy results treated with reinduction chemotherapy versus observation alone.

MATERIALS AND METHODS

We performed a retrospective study to assess the outcomes of adult patients with newly diagnosed AML treated with or without reinduction chemotherapy for indeterminate day 14 bone marrow results.

RESULTS

We identified 50 patients with indeterminate day 14 bone marrow results. Of the 50 patients, 25 (50%) had received reinduction therapy and 25 (50%) had not. Of the 50 patients, 24 (48%) had poor risk disease, 12 in the reinduction arm (10 with an abnormal karyotype and 2 with a normal karyotype with molecular abnormalities) and 12 in the observation arm (6 with an abnormal karyotype and 6 with a normal karyotype with molecular abnormalities). The overall response rate (complete remission plus complete remission with incomplete count recovery) was similar in both treatment arms (80% vs. 80%). No statistically significant difference was found in the median overall survival (13 months vs. 21 months; P = .88) or relapse-free survival (13 months vs. 33 months; P = .53) between the 2 treatment arms.

CONCLUSION

Our study did not find a statistically significant difference in the overall response rates or survival outcome measures for patients with AML and indeterminate day 14 bone marrow in the 2 treatment groups. Our findings question the utility of immediate reinduction chemotherapy and raise concern regarding overtreatment in this patient population. Larger studies investigating similar outcomes are warranted to validate our clinical findings.

A strategy of Day14 bone marrows and early intervention is not superior to a strategy of noDay14 bone marrows and delayed intervention in patients with acute myeloid leukemia

We conducted a retrospective study of 364 acute myeloid leukemia patients treated using a Day14 or a noDay14 strategy. Under the Day14 strategy, patients received an interim marrow at 7-10 days following chemotherapy and, in case of residual disease, received immediate reinduction chemotherapy. Under the noDay14 strategy patients were only evaluated at end-of-induction (EOI). Overall induction mortality was higher in the Day14 cohort (8.3 vs. 3.6%, p = .12) but rates of remission (75.4 vs. 83%, p = .13) and refractory disease (14.3 vs. 13.4%, p = .87) at EOI were similar in the Day14 and noDay14 cohorts as were relapse rates (37.9% vs. 34.3%, p = .616), median relapse-free survival (14.8 vs. 15 months, p = .658) and median overall survival (25.3 vs. 37.2 months, p = .264). In multivariate analysis, the use of a Day14 strategy did not impact outcomes suggesting that a Day14 strategy is not superior to a noDay14 strategy.

Monocytes-neutrophils-ratio as predictive marker for failure of first induction therapy in AML

INTRODUCTION

Acute myeloid leukemia (AML) is, if untreated, a fatal hematologic neoplasia. Failure of the first induction chemotherapy is a hallmark for a poor prognosis. Early recognition of therapy failure is crucial for planning further therapies. Therefore, international guidelines recommend a bone marrow biopsy around day 14 after the beginning of induction therapy. Hypocellular bone marrow on day 14 is still gold standard for therapy assessment and further therapy strategy. Despite this, non-invasive ways for the evaluation of induction therapy were looked for in the past years.

METHODS

We collected peripheral blood cell counts and routine laboratory values of patients treated with "7 + 3" induction therapy. Ratios of absolute cell counts of monocytes and neutrophils (MNR) were calculated daily, and the values were compared in patients with failure of the first induction therapy and patients with therapy response.

RESULTS

54 patients were included, 12 of which had failure of first induction therapy. The MNR following therapy was highly correlated with the bone marrow results. With the right cut-off, the MNR provides a valid and reliable tool for identification of patients with failure of first induction therapy with a sensitivity of 83.3% and a specificity of 87.8% on day 18.

CONCLUSIONS

We propose a novel and non-invasive method for detection of failure of first induction therapy in patients with de novo AML and "7 + 3" induction therapy. The MNR is free of cost since the required cell counts are performed routinely for each patient undergoing intensive chemotherapy.

In-silico comparison of two induction regimens (7 + 3 vs 7 + 3 plus additional bone marrow evaluation) in acute myeloid leukemia treatment

BACKGROUND

Clinical integration of systems biology approaches is gaining in importance in the course of digital revolution in modern medicine. We present our results of the analysis of an extended mathematical model describing abnormal human hematopoiesis. The model is able to describe the course of an acute myeloid leukemia including its treatment. In first-line treatment of acute myeloid leukemia, the induction chemotherapy aims for a rapid leukemic cell reduction. We consider combinations of cytarabine and anthracycline-like chemotherapy. Both substances are widely used as standard treatment to achieve first remission. In particular, we compare two scenarios: a single-induction course with 7 days cytarabine and 3 day of anthracycline-like treatment (7 + 3) with a 7 + 3 course and a bone marrow evaluation that leads, in case of insufficient leukemic cell reduction, to the provision of a second chemotherapy course. Three scenarios, based on the leukemias growth kinetics (slow, intermediate, fast), were analyzed. We simulated different intensity combinations for both therapy schemata (7 + 3 and 7 + 3 + evaluation).

RESULTS

Our model shows that within the 7 + 3 regimen a wider range of intensity combinations result in a complete remission (CR), compared to 7 + 3 + evaluation (fast: 64.3% vs 46.4%; intermediate: 63.7% vs 46.7%; slow: 0% vs 0%). Additionally, the number of simulations resulting in a prolonged CR was higher within the standard regimen (fast: 59.8% vs 40.1%; intermediate: 48.6% vs 31.0%; slow: 0% vs 0%). On the contrary, the 7 + 3 + evaluation regimen allows CR and prolonged CR by lower chemotherapy intensities compared to 7 + 3. Leukemic pace has a strong impact on treatment response and especially on specific effective doses. As a result, faster leukemias are characterized by superior treatment outcomes and can be treated effectively with lower treatment intensities.

CONCLUSIONS

We could show that 7 + 3 treatment has considerable more chemotherapy combinations leading to a first CR. However, the 7 + 3 + evaluation regimen leads to CR for lower therapy intensity and presumably less side effects. An additional evaluation can be considered beneficial to control therapy success, especially in low dose settings. The treatment success is dependent on leukemia growth dynamics. The determination of leukemic pace should be a relevant part of a personalized medicine.

Molecular Measurable Residual Disease Testing of Blood During AML Cytotoxic Therapy for Early Prediction of Clinical Response

Measurable residual disease (MRD) testing after initial chemotherapy treatment can predict relapse and survival in acute myeloid leukemia (AML). However, it has not been established if repeat molecular or genetic testing during chemotherapy can offer information regarding the chemotherapy sensitivity of the leukemic clone. Blood from 45 adult AML patients at day 1 and 4 of induction (n = 35) or salvage (n = 10) cytotoxic chemotherapy was collected for both quantitative real-time PCR (qPCR) assessment (WT1) and next generation sequencing (>500 × depth) of 49 gene regions recurrently mutated in MDS/AML. The median age of subjects was 62 (23–78); 42% achieved a complete response. WT1 was overexpressed in most patients tested but was uninformative for very early MRD assessment. A median of 4 non-synonymous variants (range 0–7) were detected by DNA sequencing of blood on day 1 of therapy [median variant allele frequency (VAF): 29%]. Only two patients had no variants detectable. All mutations remained detectable in blood on day 4 of intensive chemotherapy and remarkably the ratio of mutated to wild-type sequence was often maintained. This phenomenon was not limited to variants in DNMT3A, TET2, and ASXL1. The kinetics of NPM1 and TP53 variant burden early during chemotherapy appeared to be exceptions and exhibited consistent trends in this cohort. In summary, molecular testing of blood on day 4 of chemotherapy is not predictive of clinical response to cytotoxic induction therapy in AML. The observed stability in variant allele frequency suggests that cytotoxic therapy may have a limited therapeutic index for clones circulating in blood containing these mutations. Further validation is required to confirm the utility of monitoring NPM1 and TP53 kinetics in blood during cytotoxic therapy.

Comparison of Peripheral Blast Clearance and Day 14 Bone Marrow Biopsy in Predicting Remission Status and Survival After 7+3 Induction in Acute Myeloid Leukemia

INTRODUCTION

Induction chemotherapy with cytarabine and an anthracycline (7+3) remains the standard of care for acute myeloid leukemia (AML).

PATIENTS AND METHODS

We retrospectively analyzed 183 newly diagnosed AML patients to compare the utility of rapid peripheral blast clearance (PBC), day of peripheral blast disappearance, residual blasts, and cellularity at day 14 bone marrow biopsy (D14BM) in predicting clinical response to 7+3 induction, overall survival (OS), and relapse-free survival (RFS).

RESULTS

In multivariable logistic regression analysis, day 2 PBC > 85% [P = .0016] was the only predictor of remission status, with sensitivity and specificity of 75%. Peripheral blast disappearance within 5 days after induction and < 10% cellularity in D14BM predicted superior OS and RFS in multivariate analysis. Median follow-up of patients was 28 months since diagnosis. Two-year OS and RFS for patients with ≤ 10% versus > 10% cellularity at D14BM was 60.6% [95% confidence interval (CI), 50.8%-72.2%] versus 32.5% [95% CI, 23.0%-45.8%], and 51.9% [95% CI, 41.9%-64.3%] versus 28.8% [95% CI, 19.1%-43.4%], respectively [P = .0003 for OS and .002 for RFS].

CONCLUSION

Rapid PBC after 7+3 induction showed a significant improvement in specificity compared with D14BM, with similar sensitivity. Neither of these methods were reliably specific tools for the decision of early reinduction, despite their prognostic value. Our findings indicate that morphological cellularity in D14BM is an independent prognostic factor for OS and RFS, regardless of blast percentage, and that ≤ 10% cellularity defines D14BM hypoplasia.

Outcomes of fludarabine, high dose cytarabine and granulocyte-colony stimulating factor (FLAG) as re-induction for residual acute myeloid leukemia on day 14 bone marrow

BACKGROUND

Patients with acute myeloid leukemia (AML) treated with intensive chemotherapy may require re-induction based on the evaluation of day 14 bone marrow biopsy.

METHODS

A retrospective chart review was performed to evaluate adult patients with AML who received re-induction with fludarabine, high dose cytarabine and granulocyte colony stimulating factor (FLAG) regimen for residual disease (≥ 5% blasts by morphology) on day 14 bone marrow examination between September 2012 and July 2017 at our institution.

RESULTS

We identified 27 patients who received FLAG therapy for treatment of residual disease on day 14 marrow examination following initial induction. The median age at diagnosis was 61 years and the majority of patients had poor risk AML. The overall response rate was 78% and 15 patients proceeded to allogeneic hematopoietic stem cell transplantation.

CONCLUSION

The regimen was well tolerated and is a viable re-induction option for patients with residual disease on a day 14 bone marrow.

Impact of Day 14 Bone Marrow Biopsy on Re-Induction Decisions and Prediction of a Complete Response in Acute Myeloid Leukemia Cases

Background: With acute myeloid leukemia (AML), there are limited data about the accuracy of day 14 bone marrow (BM) biopsies for predicting complete remission as compared to day 28 BM biopsy results. We here aimed to estimate the correlation between, and the diagnostic accuracy of, both approaches. Materials and Methods: We reviewed 84 patients with AML treated with standard induction chemotherapy to evaluate the remission rate and treatment decisions based on day 14 BM biopsy from 2000-2012. Results: Sixty five patients (77%) demonstrated remission (CR) with less than 5% blasts on their day 14 BM. Thirteen patients (16%) had residual disease (RD), and 6 (7%) were classified as indeterminate response (IR) i.e., blasts 5-20%. Two patients with RD on day 14 underwent re-induction. Out of the 17 remaining cases with RD+IR, 14 (all 6 with IR and 8 out of 11 with residual disease with no re-induction) demonstrated a morphologic complete remission (CR) on day 28 BM. The percentages for complete remissions on days 28 and 14 were significantly different [94% versus 79.3%, respectively; p=0.004, (OR= 0.143, 95% CI: 0.032-0.63)]. Day 14 BM had 82% sensitivity in predicting CR on Day 28; however, it had insufficient specificity (60%) in predicting failure of CR. Conclusions: Induction treatment response assessment based on day 14 BM does not accurately predict the response rate on day 28 and the use of day 14 BM as a sole marker of response to therapy might expose patients to unnecessary interventions.

Day 14 bone marrow examination in the management of acute myeloid leukemia

The National Comprehensive Cancer Network (NCCN) recommends that a repeat bone marrow evaluation is carried out seven to ten days following completion of induction therapy so that if a patient's day 14 bone marrow shows residual blast cell counts of >10%, the patient would proceed early to a second cycle of induction therapy. Although blast cell counts of <5% on day 14 bone marrow is sensitive in predicting remission on day 28, various studies have found that day 14 bone marrow is highly nonspecific because a large proportion of patients with blast cell counts of >5% on day 14 bone marrow would still attain a complete remission of the disease without any further chemotherapy. Clinical decision based on day 14 bone marrow will result in some of these patients being given a second induction therapy unnecessarily. A second cycle of chemotherapy is associated with not only higher risk for treatment-related mortality but also increased use of hospital resources such as increased intravenous antimicrobials use, longer hospital stay, and higher demand for blood products. In this article, we examined the utility, discussed the shortfalls, and re-appraised the values of day 14 bone marrow in the management of patients with AML. On the basis of our review, we suggest that the practice of day 14 bone marrow examination should be re-evaluated and should probably only be carried out in the setting of clinical trials with clear questions to address its role in predicting outcome of the therapeutic intervention.

Early assessment of response to induction therapy in acute myeloid leukemia using 18F-FLT PET/CT

Background

We evaluated the suitability of ¹⁸F-fluorodeoxythymidine (¹⁸F-FLT) positron emission tomography (PET)/computed tomography (CT) for assessment of the early response to induction therapy and its value for predicting clinical outcome in patients with acute myeloid leukemia (AML). Adult patients who had histologically confirmed AML and received induction therapy were enrolled. All patients underwent ¹⁸F-FLT PET/CT after completion of induction. PET/CT images were visually and quantitatively assessed. Cases with intensely increased bone marrow uptake in more than one third of the long bones and throughout the central skeleton were interpreted as PET-positive for resistant disease (RD). PET results were compared to the clinical response and outcome.

Results

In visual PET analysis of 10 eligible patients (7 male, 3 female; median age 58 years), 5 patients were interpreted as being PET-positive and 5 as PET-negative. Standardized uptake values were significantly different between PET-positive and PET-negative groups. Eight of 10 patients achieved clinical complete remission (CR)/CR with incomplete blood count recovery (CRi). Five CR/CRi patients had PET-negative findings, but 3 CR patients had PET-positive findings. Both of the RD patients had PET-positive findings. During follow-up, 2 CR patients with PET-positive findings relapsed, or were strongly suspected of relapse, 4 months after consolidation.

Conclusion

¹⁸F-FLT PET/CT after induction therapy showed good sensitivity and negative-predictive value for evaluating RD in patients with AML. This preliminary study suggests that ¹⁸F-FLT PET/CT may be valuable as a noninvasive tool for early assessment of the response to treatment and may provide prognostic value for survival in patients with AML.

Bone marrow cellularity at day 14 is the most important predictive factor for response in patients with AML who require double-induction chemotherapy: Analysis from a large, single institution experience

In patients with acute myeloid leukemia (AML), the presence of residual disease at day 14 after primary induction therapy warrants consideration of a second induction cycle. However, data to guide retreatment decisions in such patients are presently limited. Here, we retrospectively reviewed data from 176 patients with AML treated at our institution with a second induction chemotherapy regimen because of day 14 residual disease. Clinical variables and nadir bone marrow features were assessed for correlations with complete remission (CR) and overall survival (OS). In our patient group, 59% achieved CR after a second induction course. Median OS for the entire group was 12.40 months (95% CI, 9.90-14.90) but 19.07 months (95% CI, 13.13-25.01) for those who attained a CR. Nadir marrow hypocellularity (P < 0.001) at day 14, absolute blast reduction of >50% (P = 0.030), and de novo disease status (P = 0.018) were significantly correlated with CR achievement after re-induction. Marrow hypocellularity at day 14 was the most significant predictor of CR on multivariate analysis (P < 0.001). Nadir marrow features did not independently correlate with OS when accounting for CR status. Re-induction was successful in achieving CR in most patients. Study patients who did not achieve CR were more likely to have nonhypocellular marrows.

Bone marrow evaluation for diagnosis and monitoring of acute myeloid leukemia

The diagnosis of acute myeloid leukemia (AML) can be made based on peripheral blood or bone marrow blasts. In this review, we will discuss the role of bone marrow evaluation and peripheral blood monitoring in the diagnosis, management, and follow up of AML patients. For patients with circulating blasts, it is reasonable to perform the necessary studies needed for diagnosis and risk stratification, including multiparametric flow cytometry, cytogenetics, and molecular analysis, on a peripheral blood specimen. The day 14 marrow is used to document hypocellularity in response to induction chemotherapy, but it is unclear if that assessment is necessary as it often does not affect immediate management. Currently, response assessments performed at count recovery for evaluation of remission and measurable residual disease rely on bone marrow sampling. For monitoring of relapse, peripheral blood evaluation may be adequate, but the sensitivity of bone marrow testing is in some cases superior. While bone marrow evaluation can certainly be avoided in particular situations, this cumbersome and uncomfortable procedure currently remains the de facto standard for response assessment.

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.

Prospective comparison of early bone marrow evaluation on day 5 versus day 14 of the "3 + 7" induction regimen for acute myeloid leukemia

Evaluation of early response during induction therapy for acute myeloid leukemia (AML) is used for prognostication and re-induction strategy, yet the optimal evaluation time point is unknown. Clearance of bone marrow (BM) blasts by day 14 of therapy does not ensure remission; thus, some patients requiring re-induction are neglected. This study aimed to examine the role of earlier BM evaluation during induction for predicting remission and overall survival. Results of BM testing on the 5th and 14th day of intensive induction were prospectively compared in 127 adult patients with AML. Re-induction was given, based on Day 14 results, to 25 patients. Reduction of the BM blast count to <5% as early as by the fifth day of induction was more specifically associated with the achievement of remission compared to Day 14 (88.2% vs. 60%, respectively). Rapid responders have a better 3-year overall survival (OS). Day 5 results are a stronger predictor of OS by multivariate analysis and better segregate long-term survivors than the Day 14th BM count (66% vs. 30%, P = 0.0001 and 48% vs. 37%, respectively, P = 0.04). The Day 5 evaluation of BM carries significant clinical information. The benefit of prescribing re-induction based on such early evaluation should be prospectively studied.

Randomized multicenter phase II study of flavopiridol (alvocidib), cytarabine, and mitoxantrone (FLAM) versus cytarabine/daunorubicin (7+3) in newly diagnosed acute myeloid leukemia

Serial studies have demonstrated that induction therapy with FLAM [flavopiridol (alvocidib) 50 mg/m(2) days 1-3, cytarabine 667 mg/m(2)/day continuous infusion days 6-8, and mitoxantrone (FLAM) 40 mg/m(2) day 9] yields complete remission rates of nearly 70% in newly diagnosed poor-risk acute myeloid leukemia. Between May 2011-July 2013, 165 newly diagnosed acute myeloid leukemia patients (age 18-70 years) with intermediate/adverse-risk cytogenetics were randomized 2:1 to receive FLAM or 7+3 (cytarabine 100 mg/m(2)/day continuous infusion days 1-7 and daunorubicin 90 mg/m(2) days 1-3), across 10 institutions. Some patients on 7+3 with residual leukemia on day 14 received 5+2 (cytarabine 100 mg/m(2)/day continuous infusion days 1-5 and daunorubicin 45 mg/m(2) days 1-2), whereas patients on FLAM were not re-treated based on day 14 bone marrow findings. The primary objective was to compare complete remission rates between one cycle of FLAM and one cycle of 7+3. Secondary end points included safety, overall survival and event-free survival. FLAM led to higher complete remission rates than 7+3 alone (70% vs. 46%; P=0.003) without an increase in toxicity, and this improvement persisted after 7+3+/-5+2 (70% vs. 57%; P=0.08). There were no significant differences in overall survival and event-free survival in both arms but post-induction strategies were not standardized. These results substantiate the efficacy of FLAM induction in newly diagnosed AML. A phase III study is currently in development. This study is registered with clinicaltrials.gov identifier: 01349972.

New methods for assessing response in acute myeloid leukemia

PURPOSE OF REVIEW

Patients with acute myeloid leukemia typically are monitored with bone marrow biopsy 7-10 days after completion of induction therapy. However, this test has relatively poor sensitivity and specificity for classifying patients likely to have long-term cure or even patients who will need additional therapy to achieve complete remission. Several new methods of assessing response are being studied and are summarized in this review.

RECENT FINDINGS

Many new methods are being used to evaluate response assessment. Emerging data suggest that various types of clinical, chemical, and imaging biomarkers, as well as more sensitive techniques to measure minimal residual disease, can all help provide more accurate response assessment and prognostic information.

SUMMARY

New techniques will improve the way we assess response to acute myeloid leukemia therapy. Larger confirmatory studies utilizing these novel markers of response to change treatment and to improve clinical outcomes are urgently needed.