Minimal Residual Disease Evaluation Research Articles

Predictive Power of Early, Sequential MRD Monitoring in Peripheral Blood and Bone Marrow in Patients with Mantle Cell Lymphoma Following Autologous Stem Cell Transplantation with or without Rituximab Maintenance; Final Results from the LyMa-MRD Project, Conducted on Behalf of the Lysa Group

Predictive Power of Early, Sequential MRD Monitoring in Peripheral Blood and Bone Marrow in Patients with Mantle Cell Lymphoma Following Autologous Stem Cell Transplantation with or without Rituximab Maintenance; Final Results from the LyMa-MRD Project, Conducted on Behalf of the Lysa Group

Clinical Outcomes of Patients with Secondary Acute Myeloid Leukemia (sAML) Treated with Hypomethylating Agent Plus Venetoclax (HMA-Ven) or Liposomal Daunorubicin Cytarabine (CPX-351)

Clinical Outcomes of Patients with Secondary Acute Myeloid Leukemia (sAML) Treated with Hypomethylating Agent Plus Venetoclax (HMA-Ven) or Liposomal Daunorubicin Cytarabine (CPX-351)

Ibrutinib (Ibr) Plus Venetoclax (Ven) for First-Line Treatment of Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Lymphoma (SLL): 1-Year Disease-Free Survival (DFS) Results From the MRD Cohort of the Phase 2 CAPTIVATE Study

Ibrutinib (Ibr) Plus Venetoclax (Ven) for First-Line Treatment of Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Lymphoma (SLL): 1-Year Disease-Free Survival (DFS) Results From the MRD Cohort of the Phase 2 CAPTIVATE Study

Survival Analysis of Newly Diagnosed Transplant-Eligible Multiple Myeloma Patients in the Randomized Forte Trial

Survival Analysis of Newly Diagnosed Transplant-Eligible Multiple Myeloma Patients in the Randomized Forte Trial

Minimal Residual Disease Monitoring from Liquid Biopsy By Next Generation Sequencing in Follicular Lymphoma Patients

Minimal Residual Disease Monitoring from Liquid Biopsy By Next Generation Sequencing in Follicular Lymphoma Patients

Minimal Residual Disease Assessment Is an Independent Prognostic Factor in Splenic Marginal Zone Lymphoma

Purpose: Splenic marginal lymphoma (SMZL) is a rare indolent B-cell lymphoma with long survival. The minimal residual disease (MRD) detection in indolent B-cell lymphomas has shown power in predicting survival and even in guiding treatment duration in chronic lymphocytic leukemia. As almost all SMZL patients have bone marrow involvement (BMI) at diagnosis, we prospectively designed the MRD detection during treatment to study its prognostic value in SMZL. Methods: SMZL patients who needed chemotherapy would regularly monitor the MRD status until undetectable MRD by multiparameter flow cytometry (MFC). Patients with MRD under 0.01% were defined as uMRD. Other clinical factors were also analysed as prognostic factors. Results: In total, 71 patients with frontline therapy were enrolled in this study. There were 284 evaluable BM MRD samples. At end of treatment, 55 patients (77.4%) got uMRD, 10 patients had a MRD level of 0.01-1%, and 6 patients had a MRD level of ≥ 1%. The uMRD rate increased at the end of treatment. With a median follow-up of 50 (24-157) months, uMRD patients showed superior outcomes compared with MRD-positive patients. Patients with uMRD had a significant better progression free survival (PFS) compared to those with MRD. PR with positive-MRD after induction therapy was a significantly poor predictor for PFS and overall survival (OS). Multivariate prognostic analysis showed it was a powerful independent prognostic factor for PFS [HR=0.357 (95%CI 0.131-0.972), P=0.044]. Conclusion: uMRD in BM was an independent prognostic factor in SMZL patients, especially for the patients only achieving PR at the end of therapy. Figure Disclosures No relevant conflicts of interest to declare.

Cranial Radiation Can be Eliminated in Most Children with T-Cell Acute Lymphoblastic Leukemia (T-ALL) and Bortezomib Potentially Improves Survival in Children with T-Cell Lymphoblastic Lymphoma (T-LL): Results of Children's Oncology Group (COG) Trial AALL1231

Cranial Radiation Can be Eliminated in Most Children with T-Cell Acute Lymphoblastic Leukemia (T-ALL) and Bortezomib Potentially Improves Survival in Children with T-Cell Lymphoblastic Lymphoma (T-LL): Results of Children's Oncology Group (COG) Trial AALL1231

Phase II Trial of In Vivo Purging with Daratumumab in Newly Diagnosed Multiple Myeloma

Phase II Trial of In Vivo Purging with Daratumumab in Newly Diagnosed Multiple Myeloma

Comparative Efficacy of First-Line Chemotherapy-Free Combinations in Chronic Lymphocytic Leukemia (CLL): A Network Meta-Analysis

Introduction: Chronic Lymphocytic Leukemia (CLL) is an incurable B-cell malignancy which disproportionately affects the elderly. Although first-line chemoimmunotherapy (CIT) improved CLL clinical outcomes, recent randomized trials revealed superior outcomes with novel chemotherapy-free combinations (CFC) incorporating anti-CD20 monoclonal antibodies and inhibitors of BTK or Bcl-2. So far, these CFC have not been compared head-to-head. We conducted this network meta-analysis to evaluate their relative efficacy to each other. Methods: A review of the medical literature was conducted using online databases. Inclusion criteria consisted of English language; diagnosis of CLL; trials that explored the efficacy of first-line CFC with Obinutuzumab (O), Rituximab (R), Ibrutinib (IB), Acalabrutinib (ACAL), Venetoclax (VEN) compared to standard CIT that included Chlorambucil (CHLOR) with either R or O, Bendamustine+Rituximab, or Fludarabine+ Cyclophosphamide+R; and phase 3 randomized studies reporting responses, progression, death, and adverse (AE) events. A frequentists network meta-analysis was conducted using netmeta package and random-effects model. Results: Five studies comprising a total of 2,272 participants were included. When O-based CFC data was analyzed, only ACAL-O had a significant lower relative risk (RR) of progression and death (P&D). There were no significant differences with respect to overall response rates (ORR), complete remission (CR), minimal residual disease (MRD), or grade >3 adverse events (Grd3+) among O-based CFC. When R-based CFC data was analyzed, IB and IB-R were not different with respect to RR of P&D, ORR, CR, MRD, or Grd3+. When the data was analyzed as CFC versus combined CIT, only ACAL-O was found to be significantly superior to other O- and R-based CFC with respect to RR of P&D. ORR and Grad3+ rates of O- and R-based CFC were not significantly different. While ACAL-O, IB-O, and VEN-O had superior CR and MRD rates compared to other CFC, there were no significant differences among each other. Conclusions: This network meta-analysis is the first to compare and rank first-line CFC therapies in CLL. It indicates that ACAL-O has a superior profile having the lowest RR of P&D without significant difference in Grd3+ among CFC. Disclosures No relevant conflicts of interest to declare.

Role of Imaging in the Evaluation of Minimal Residual Disease in Multiple Myeloma Patients.

The International Myeloma Working Group (IMWG) recently introduced the evaluation of minimal residual disease (MRD) within the multiple myeloma (MM) response criteria, and MRD negativity assessed inside and outside the bone marrow is currently considered the most powerful predictor of favorable long-term outcomes. However, MRD evaluation has thus far relied on flow-cytometry or molecular-based methods, despite the limitations associated with the patchy infiltration of bone marrow (BM) plasma cells and the presence of extra-medullary (EMD). On the contrary, imaging-based sensitive response assessment through the use of functional rather than morphological whole-body (WB) imaging techniques, such as positron emission tomography with computed tomography (PET/CT) and magnetic resonance imaging (MRI), likely is a promising strategy to overcome these limitations in evaluating response to therapy and in the assessment of the MRD status in MM patients. However, despite the significant advances in the development and availability of novel functional imaging techniques for MRD evaluation, a worldwide standardization of imaging criteria for acquisition, interpretation, and reporting is yet to be determined and will be object of future investigations.

Comparison of next-generation sequencing (NGS) and next-generation flow (NGF) for minimal residual disease (MRD) assessment in multiple myeloma

Detecting persistent minimal residual disease (MRD) allows the identification of patients with an increased risk of relapse and death. In this study, we have evaluated MRD 3 months after transplantation in 106 myeloma patients using a commercial next-generation sequencing (NGS) strategy (LymphoTrack®), and compared the results with next-generation flow (NGF, EuroFlow). The use of different marrow pulls and the need of concentrating samples for NGS biased the applicability for MRD evaluation and favored NGF. Despite that, correlation between NGS and NGF was high (R2 = 0.905). The 3-year progression-free survival (PFS) rates by NGS and NGF were longer for undetectable vs. positive patients (NGS: 88.7% vs. 56.6%; NGF: 91.4% vs. 50%; p < 0.001 for both comparisons), which resulted in a 3-year overall survival (OS) advantage (NGS: 96.2% vs. 77.3%; NGF: 96.6% vs. 74.9%, p < 0.01 for both comparisons). In the Cox regression model, NGS and NGF negativity had similar results but favoring the latter in PFS (HR: 0.20, 95% CI: 0.09–0.45, p < 0.001) and OS (HR: 0.21, 95% CI: 0.06–0.75, p = 0.02). All these results reinforce the role of MRD detection by different strategies in patient prognosis and highlight the use of MRD as an endpoint for multiple myeloma treatment.

Integration of Next-Generation Sequencing in Diagnosing and Minimal Residual Disease Detection in Patients With Philadelphia Chromosome-Like Acute Lymphoblastic Leukemia.

Philadelphia-like (Ph-like) acute lymphoblastic leukemia (ALL) is a high-risk subtype of B cell ALL. It accounts for 20% of all B cell ALL cases and is similar to BCR-ABL1 in gene expression profile but lacks BCR-ABL fusion. It is highly heterogeneous and is characterized by genetic alterations that activate kinase and cytokine receptor signaling. Most of these alterations are amenable to tyrosine kinase inhibitors. Ph-like ALL is prevalent in pediatric and young adults, more common in males, and frequently seen in patients with Hispanic ancestry. It is associated with inadequate response to induction therapy, high minimal residual disease (MRD) levels, and increased risk of relapse. Overall survival and event-free survival are also inferior in these patients as compared to non-Ph-like ALL. In the clinical practice, low-density array, real-time quantitative polymerase chain reaction (RQ-PCR), flow cytometry, fluorescence in situ hybridization are used to identify genetic alteration in these patients. With the advent of next-generation sequencing (NGS), our understanding of disease pathogenesis and precision medicine has been improved. In this review, we analyzed data from several studies that used NGS as one of the diagnostic methods to identify genomic lesions in this high-risk subtype of B cell ALL. Studies have shown that NGS is a vital technique to identify various genomic lesions at diagnosis and throughout the treatment that can be missed by the widely used current methods. NGS has improved our understanding of various genomic lesions associated with Ph-like ALL and has helped define disease pathogenesis, MRD evaluation, and stratify therapy to prevent over or under treatment. We are in the era of precision medicine. Therefore unbiased, comprehensive genomic characterization of Ph-like ALL is important to implicate treatment directed against these genomic lesions and improve outcomes in these patients. We also analyzed data from studies that compared NGS with multi-flow cytometry and RQ-PCR for the evaluation of MRD. In the future, more extensive prospective studies are required to confirm the prognostic usefulness of NGS.

Minimal Residual Disease in Multiple Myeloma: State of the Art and Applications in Clinical Practice

Novel drugs have revolutionized multiple myeloma therapy in the last 20 years, with median survival that has doubled to up to 8–10 years. The introduction of therapeutic strategies, such as consolidation and maintenance after autologous stem cell transplants, has also ameliorated clinical results. The goal of modern therapies is becoming not only complete remission, but also the deepest possible remission. In this context, the evaluation of minimal residual disease by techniques such as next-generation sequencing (NGS) and next-generation flow (NGF) is becoming part of all new clinical trials that test drug efficacy. This review focuses on minimal residual disease approaches in clinical trials, with particular attention to real-world practices.

MM-252: Aberrant Plasma Cells in the Apheresis Product as a Prognostic Factor for Minimal Residual Disease Negativity After Transplant in Newly Diagnosed Myeloma Patients

Context: Autologous stem cell transplantation (ASCT) is the standard frontline therapy for newly diagnosed multiple myeloma (MM) eligible patients. “Contamination” of leukapheresis products with aberrant plasma cells (PCs) has been considered as a possible predictive factor for response and outcome. Objective: To evaluate the frequency and clinical value of clonal PCs remaining in leukapheresis products using next generation flow cytometry (NGFC), which is able to detect aberrant clonal PCs at levels reaching 10−6. Design: Prospective study. Setting: A referral center in Athens, Greece. Patients: MM patients after four cycles of induction therapy (VCD or VRD) followed by ASCT in the Department of Clinical Therapeutics, University of Athens, Greece. Interventions: Ninety-eight patients with newly diagnosed multiple myeloma were assessed for the presence of clonal PCs with the 8-color NGFC protocol suggested by EuroFlow. Eight to ten million cells were examined; the median sensitivity of the test was 2–4 × 10−6 per sample. All patients received high-dose melphalan and ASCT. Using the same NGFC protocol, 53 patients who achieved complete response (CR) post-ASCT, based on the IMWG criteria, were also examined for the presence of minimal residual disease (MRD). Main outcome measures: Aberrant PCs in leukapheresis products. Results: This analysis revealed 58 (59%) “uncontaminated” (con-) and 40 (41%) “contaminated” (con+) leukapheresis products. The majority of con+ cases had very low numbers of aberrant plasma cells detected; 18 (45%) at the level of 10−615 (38%) at the level of 10−4 and 7 (18%) at levels ≥10−3. On day 100 post-ASCT, MRD evaluation was performed on 33 con- and 20 con+ patients, who had achieved CR. MRD positivity was found in 11 out of 53 cases (20.8%). Only 3 out of 33 (9.1%) con- patients were found MRD+, all of which at very low levels ( Conclusions: Using NGFC, we were able to detect aberrant plasma cells in 40% of apheresis products at the level of 10−6. The presence of aberrant plasma cells in the apheresis products correlates with higher probability for MRD+ after ASCT, whereas their absence predicts MRD negativity.

CLL-092: Phase 3 Trial of Acalabrutinib in Combination with Venetoclax, With and Without Obinutuzumab Versus Chemoimmunotherapy for Previously Untreated Chronic Lymphocytic Leukemia (CLL)

Context Acalabrutinib is a next-generation Bruton tyrosine kinase inhibitor (BTKi) approved in patients with relapsed/refractory or treatment-naive (TN) CLL/small lymphocytic lymphoma based on two phase 3 trials (ASCEND and ELEVATE-TN). Combining a BTKi with an anti-CD20 antibody (obinutuzumab [obi]) and a BCL-2 inhibitor (venetoclax [ven]) has the potential to achieve deeper responses and prolong progression-free survival (PFS). Objective To evaluate the efficacy and safety of acalabrutinib in combination with ven ± obi vs chemoimmunotherapy (CIT) in TN CLL. Design Phase 3, randomized (1:1:1), open-label trial (ACE-CL-311; NCT03836261). Setting Global, multicenter study. Patients Adult patients with untreated CLL without del(17p) or TP53 mutation. Interventions Patients are randomized to receive oral acalabrutinib 100 mg BID (28-day cycles, up to 14 cycles) + oral ven QD (cycles 3–4; ramp-up followed by 400 mg/day) (Arm A), acalabrutinib + ven + infusion of obi (cycles 2–7) (Arm B), or CIT (Arm C: up to 6 cycles of fludarabine/cyclophosphamide/rituximab [only in patients aged ≤65 years] or bendamustine/rituximab [BR]). Main outcome measures ACE-CL-311 began in February 2019 and is currently recruiting (target enrollment: 780 patients, >200 sites). Patients must have an Eastern Cooperative Oncology Group performance status ≤2, fulfill International Workshop on Chronic Lymphocytic Leukemia 2018 criteria for CLL diagnosis and treatment, and adequate organ function. Key exclusion criteria include stroke or intracranial hemorrhage, significant cardiovascular disease, bleeding disorders, or required treatment with warfarin or equivalent vitamin K antagonists or a strong cytochrome P450 inhibitor. Patients will be evaluated for efficacy and observed until progressive disease. Primary efficacy endpoint is independent review committee (IRC)-assessed PFS (Arm A vs C). Secondary efficacy endpoints include IRC- and investigator-assessed PFS, undetectable minimal residual disease rates, objective response rate, event-free survival, duration of response, time to next therapy, and overall survival. Safety objectives include incidence and severity of adverse events. Patients will be stratified based on age (>65 vs ≤65 years), immunoglobulin heavy chain variable region mutational status, Rai stage risk (≥3 vs Results Trial in progress. Conclusion Study is currently recruiting.

Immunoglobulin kappa deleting element rearrangements are candidate targets for minimal residual disease evaluation in mantle cell lymphoma.

Minimal residual disease (MRD) assessment is of high clinical relevance in patients with mantle cell lymphoma (MCL). In mature B-cell malignancies, the presence of somatic hypermutations (SHM) in Variable-Diversity-Joining Heavy chain (VDJH) rearrangements leads to frequent mismatches between primers, probes, and the target, thus impairing tumor cells quantification. Alternative targets, such as immunoglobulin kappa-deleting-element (IGK-Kde) rearrangements, might be suitable for MRD detection. We aimed at evaluating the applicability of IGK-Kde rearrangements for MRD quantification in MCL patients by real-time quantitative polymerase chain reaction (RQ-PCR)/digital-droplet-PCR (ddPCR). IGK screening was performed on bone marrow samples from two cohorts: the first from Turin (22 patients enrolled in the FIL-MCL0208 trial, NCT02354313) and the second from Rome (15 patients). IGK-Kde rearrangements were found in 76% (28/37) of cases, representing the sole molecular marker in 73% (8/11) of IGH-BCL1/IGH negative cases. MRD RQ-PCR monitoring was possible in 57% (16/28) of cases, showing a 100% concordance with the conventional targets. However, the frequent background amplification affected the sensitivity of the assay, that was lower in MCL compared to acute lymphoblastic leukemia and in line with multiple myeloma published results. ddPCR had a good concordance with RQ-PCR and it might help to identify false positive/negative results. From a clinical perspective, we suggest that IGK-Kde can be a candidate target for MRD monitoring and deserves a validation of its predictive value in prospective MCL series.

Next generation flow cytometry for MRD detection in patients with AL amyloidosis

The treatment of AL amyloidosis aims to eradicate the plasma cell clone and eliminate toxic free light chain production. Only in a minority of patients the plasma cell clone is completely eradicated; residual light chain production may still exist while clonal relapse may occur. We used sensitive next-generation flow cytometry (NGF) to detect minimal residual disease (MRD) in AL amyloidosis patients at complete haematologic response. MRD evaluation was feasible in 51 of 52 (98%) tested patients and at a median sensitivity of 2.3 × 10−6 MRD was undetectable in 23 (45%). An organ response occurred in 86% of MRDneg vs 77% in MRDpos; renal response in 15/17(88%) of MRDneg vs in 14/16(87.5%) of MRDpos and cardiac response in 10/10(100%) of MRDneg vs 11/15(73%) of MRDpos patients. After a median follow-up of 24 months post MRD testing, no MRDneg patient had a haematologic relapse vs 6/28(21%) MRDpos (p = .029). Pooling haematologic and organ progressions, 9 (32%) MRDpos patients had disease progression vs only 1 (4%) MRDneg patient (p = .026). In conclusion, MRD detection using NGF has profound clinical implications, so that AL patients with undetectable MRD have a very high probability of organ response and a very low probability of haematologic relapse.

SO-34 Clinical experience of a personalized and tumor-informed circulating tumor DNA assay for minimal residual disease detection in oligometastatic colorectal cancer patients

For patients with oligometastatic colorectal cancer (CRC) treated with definitive management with curative intent, upwards of 50% still recur post-resection.1,2 Circulating tumor DNA (ctDNA) testing can be used to assess minimal residual disease (MRD) in patients with oligometastatic CRC and predict the risk of recurrence. Prospective evaluation of this methodology in clinical practice has been limited to date and the use of chemotherapy after metastasectomy is largely based on data extrapolated from earlier stage CRC. A personalized and tumor-informed multiplex PCR assay (Signatera™ bespoke mPCR NGS assay) was used for the detection and quantification of ctDNA for MRD assessment. We analyzed and present results from an ongoing early adopter program of ctDNA testing in patients with oligometastatic CRC (largely isolated to the liver) treated with surgery, radiation, or other definitive metastasis therapy. Adjuvant therapy was given at the discretion of the treating physician. ctDNA levels were analyzed on an average of 55 days post oligometastatic disease resection/ablation (range 3 – 150 days, median 52 days) in a total of 31 oligometastatic CRC patients. Post-treatment MRD was detected in 15 patients (48.4%), with an average of 74 mean tumor molecules per mL (range 0.11 - 673 MTM/mL; median 4.83 MTM/mL). Using the same assay, MRD rates after surgery were lower (up to 24%) in historical stage I-III CRC patients. Longitudinal case studies describing the ctDNA clearance effects of systemic therapy on MRD rates in the post-metastasectomy setting will be presented. This is the largest set of clinical experience data analyzing ctDNA in oligometastatic CRC patients and shows definitive evidence that a highly sensitive MRD assay can detect residual disease after curative intent procedures. An average MRD rate of 48.4% is consistent with published relapse rates of ∼50% post-oligometastatic resection, suggesting this assay accurately measures residual disease and may be prognostic for relapse, as well as potentially predictive for who might benefit from post-metastasectomy adjuvant chemotherapy.

P-283 Analysis of KRAS mutation allele in circulating cell-free DNA derived from urine in colorectal cancer patients

Liquid biopsy is widely introduced in various malignant diseases and it provides crucial clinical information on genetic profiles. Cell-free DNA (cfDNA) derived from peripheral blood has been studied mainly. However, other body fluids also have potential to provide molecular information. Urine could be a novel and completely noninvasive source to provide genetic information. The aim of this study was to evaluate the quantity of cfDNA derived from urine in colorectal cancer patients. The accuracy of KRAS mutation allele detection was also analyzed using droplet digital PCR (ddPCR). Urine, peripheral blood and tissue samples were collected from consecutively resected colorectal cancer patients. DNA was extracted from each sample and the quantity was measured. From each DNA sample, ddPCR was performed to detect common point mutations in KRAS oncogene. A total of 143 patients were enrolled. In all patients, plasma and urine cfDNA were successfully extracted and the quality and quantity were appropriate for genetic analysis. The concentration of urine cfDNA was significantly higher than that of plasma (2448 ng/ml vs. 267 ng/ml, p< 0.05). Neither plasma nor urine cfDNA concentration correlated with cancer staging. In tumor tissue DNA, KRAS mutation allele was detected in 95 patients (66.4%), KRAS mutation was detected in 21 patients from plasma and 13 patients from urine. The concordant rate of KRAS mutation allele detection between tumor tissue DNA and plasma cfDNA was 22.1%, and between tumor tissue DNA and urine cfDNA was 13%. In the early stage patients (stage I and II), the detection rate of KRAS mutation allele was similar in plasma and urine cfDNA (15.6% vs. 15.6%), however, in advanced-stage patients (stage III and IV), the detection rate in urine cfDNA was lower than that in plasma DNA (15.9% vs. 25.4%). Furthermore, urine cfDNA had a lower detection rate of KRASmutation than plasma cfDNA in stage I and IV patients (stage I; plasma cfDNA 14%, urine cfDNA 0%, stage IV; plasma cfDNA 52%, urine cfDNA 12%), however, the detection rates were equivalent in stage II and III patients (stage II; plasma cfDNA 16%, urine cfDNA 20%, stage III; plasma cfDNA 16%, urine cfDNA 16%). Our data indicated that urine cfDNA is a useful source in complementing genetic analysis in colorectal cancer patients. The sensitivity seems to be inferior especially in advanced stage, however, it will be considered useful for evaluation of minimal residual disease in stage II and III colorectal cancer patients.

Clinicoepidemiologic Profile and Outcome Predicted by Minimal Residual Disease in Children With Mixed-phenotype Acute Leukemia Treated on a Modified MCP-841 Protocol at a Tertiary Cancer Institute in India.

Mixed-phenotype acute leukemia (MPAL) accounts for 1.2% to 5% of acute leukemia across age groups with intermediate prognosis. We evaluated clinicoepidemiologic profiles and outcomes of MPAL. Records of children younger than 15 years of age with acute leukemia from January 2010 to December 2016 were reviewed on the basis of the MPAL WHO 2008 criteria. Treatment was uniform with a modified MCP-841 protocol. Descriptive analysis tools were used. Outcomes were measured by the Kaplan-Meier method on MedCalc, version 14.8.1. Among 3830 children with acute leukemia in the study period, 2892 received treatment from our center, of whom 24 (0.83%) had MPAL, median age 9 years, with a male:female ratio of 3:1, and median white blood cell of 13.4×10/L. Common immunophenotypes were B/myeloid-12 (50%), T/myeloid-9 (37.5%), and B/T-lymphoid-3 (12.5%). Some B/myeloid cases had abnormal cytogenetics. Seventeen patients were evaluable for outcome. Sixteen patients underwent postinduction bone marrow and 13 (81%) achieved morphologic remission. Thirteen patients underwent flow cytometry-based minimal residual disease evaluation; 9 (69%) were <0.01% (4 postinduction, 5 postconsolidation), and 67% of these had sustained remission till the last follow-up. None underwent bone marrow transplant. The projected 3-year event-free and overall survival rates were 40% and 48%, respectively (median follow-up: 22 mo). MPAL represented <1% of childhood acute leukemia. acute lymphoblastic leukemia-type chemotherapy that incorporated high-dose cytarabine was effective in achieving an minimal residual disease-negativity rate of 69% in evaluated patients, which was also predictive of better outcome.