Allogeneic hematopoietic stem cell transplantation for adult patients with mixed phenotype acute leukemia: results of a matched-pair analysis

T/myeloid mixed-phenotype acute leukemia treated with venetoclax and decitabine: A case report

BACKGROUND

Mixed-phenotype acute leukemia (MPAL) is characterized by acute undifferentiated leukemia with blasts co-expressing myeloid and lymphoid antigens. However, consensus regarding the ideal management strategy for MPAL is yet to be established, owing to its rarity.

CASE SUMMARY

A 55-year-old male was diagnosed with T/myeloid MPAL. Vincristine, prednisolone, daunorubicin, and L-asparaginase were administered as induction chemotherapy. Septic shock occurred 10 days after induction, and bone marrow examination following recovery from sepsis revealed refractory disease. Venetoclax and decitabine were administered as chemotherapy-free induction therapy to reduce the infection risk. There were no serious infections, including febrile neutropenia, at the end of the treatment. After receiving two additional cycles of venetoclax/decitabine, the patient underwent haploidentical peripheral blood stem-cell transplantation and achieved complete response (CR) to treatment.

CONCLUSION

CR was maintained in a patient with MPAL who underwent haploidentical peripheral blood stem-cell transplantation after additional venetoclax/decitabine cycles.

Outcomes with high dose cytarabine and mitoxantrone induction for adults with mixed phenotype acute leukemia

The optimal induction strategy for mixed phenotype acute leukemia (MPAL) is unknown, though retrospective data has shown improved remission rates and overall survival with acute lymphoblastic leukemia (ALL)-based regimens. At Memorial Sloan Kettering Cancer Center (MSKCC), the most utilized induction regimen for MPAL is high dose cytarabine plus mitoxantrone ("ALL-2"), though outcomes with this regimen are not well described. In this study, outcomes to first-line induction chemotherapy in 24 patients at MSKCC with MPAL classified by 2016 World Health Organization criteria are reported. The overall response rate was 94 % (16 of 17) in patients receiving ALL-2, including 86 % (6 of 7) in patients with extramedullary disease. Thirteen patients who received ALL-2 induction proceeded to allogeneic hematopoietic cell transplant (allo-HCT). The most common toxicity associated with ALL-2 was febrile neutropenia, documented in 12 patients. With a median follow-up of 37 months, median overall survival was not reached in the ALL-2 cohort, and 3-year overall survival was 62 %. In multivariate analysis, age ≥ 60 years and MPAL with isolated extramedullary disease were associated with significantly worse overall survival (P = .009 and P = .01, respectively). These results support further prospective investigation of ALL-2 as a front-line induction regimen for adults with MPAL.

Integrative genomic and transcriptomic profiling reveals distinct molecular subsets in adult mixed phenotype acute leukemia

Mixed phenotype acute leukemia (MPAL) is a subtype of leukemia in which lymphoid and myeloid markers are co-expressed. Knowledge regarding the genetic features of MPAL is lacking due to its rarity and heterogeneity. Here, we applied an integrated genomic and transcriptomic approach to explore the molecular characteristics of 176 adult patients with MPAL, including 86 patients with T-lymphoid/myeloid MPAL (T/My MPAL-NOS), 42 with Ph+ MPAL, 36 with B-lymphoid/myeloid MPAL (B/My MPAL-NOS), 4 with t(v;11q23), and 8 with MPAL, NOS, rare types. Genetically, T/My MPAL-NOS was similar to B/T MPAL-NOS but differed from Ph+ MPAL and B/My MPAL-NOS. T/My MPAL-NOS exhibited higher CEBPA, DNMT3A, and NOTCH1 mutations. Ph+ MPAL demonstrated higher RUNX1 mutations. B/T MPAL-NOS showed higher NOTCH1 mutations. By integrating next-generation sequencing and RNA sequencing data of 89 MPAL patients, we defined eight molecular subgroups (G1-G8) with distinct mutational and gene expression characteristics. G1 was associated with CEBPA mutations, G2 and G3 with NOTCH1 mutations, G4 with BCL11B rearrangement and FLT3 mutations, G5 and G8 with BCR::ABL1 fusion, G6 with KMT2A rearrangement/KMT2A rearrangement-like features, and G7 with ZNF384 rearrangement/ZNF384 rearrangement-like characteristics. Subsequently, we analyzed single-cell RNA sequencing data from five patients. Groups G1, G2, G3, and G4 exhibited overexpression of hematopoietic stem cell disease-like and common myeloid progenitor disease-like signatures, G5 and G6 had high expression of granulocyte-monocyte progenitor disease-like and monocyte disease-like signatures, and G7 and G8 had common lymphoid progenitor disease-like signatures. Collectively, our findings indicate that integrative genomic and transcriptomic profiling may facilitate more precise diagnosis and develop better treatment options for MPAL.

Use of midostaurin in mixed phenotype acute leukemia with FLT3 mutation: A case series

Mixed phenotype acute leukemia (MPAL) is a rare type of acute leukemia where blasts present phenotypes from more than one lineage. A poor prognostic has been associated with this disease, and limited data are currently available to guide the choice of therapy. Regarding FLT3-positive MPAL, only one case treated with midostaurin has been published to date. Here, we report the successful use of midostaurin to treat three FLT3-positive MPAL T/myeloid and B/myeloid patients. Midostaurin was successfully added to intensive induction (two patients) and consolidation chemotherapy (three patients) without significant adverse events requiring a dose adjustment or discontinuation. The therapy received resulted in complete remission for two patients and complete remission with an incomplete hematologic recovery for the third. All patients proceeded to HSCT and stayed in remission after an extended follow-up respectively at 28, 31, and 11 months later. These results suggest that the addition of midostaurin during induction and consolidation therapy may represent a treatment option for FLT3-positive MPAL.

Efficacy of combination of venetoclax with azacitidine or chemotherapy in refractory/relapse acute leukemias of ambiguous lineage, not otherwise specified

Acute leukemias of ambiguous lineage, not otherwise specified (ALAL-NOS) is a rare type of acute leukemia. Management of relapse/refractory (R/R) patients is still challenging.traditional chemotherapy treatment is not effective. In this paper, we reported 6 R/R patients diagnosed as ALAL-NOS in our hospital, who were treated with venetoclax based treatment (venetoclax combining with azacitidine or chemotherapy). All 6 patients achieved CR. Five of the six patients received allo-HSCT, four patients were still alive in CR until the follow-up day. Our data provide preliminary evidence and show that venetoclax based regimens are effective and safety in patients with R/R ALAL-NOS.

Pediatric Mixed-Phenotype Acute Leukemia: What's New?

Simple Summary

Pediatric mixed-phenotype leukemia is a rare form of blood cancer in children. In this review, we cover both the evolution of treatment over the past several years and outline new emerging concepts in this disease.

Abstract

Mixed-phenotype acute leukemias (MPAL) are rare in children and often lack consensus on optimal management. This review examines the current controversies and emerging paradigms in the management of pediatric MPAL. We examine risk stratification, outcomes of recent retrospective and prospective collaborative trials, and the role of transplantation and precision genomics, and outline emerging targets and concepts in this rare entity.

Early T-Cell Precursor Acute Lymphoblastic Leukemia and T/Myeloid Mixed Phenotype Acute Leukemia Possess Overlapping Characteristics and Both Benefit From CAG-Like Regimens and Allogeneic Hematopoietic Stem Cell Transplantation

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) and T-lymphoid/myeloid mixed phenotype acute leukemia (T/M-MPAL) are closely related entities and remain a therapeutic challenge. In this study, we characterized the clinical features of 43 ETP-ALL and 41 T/M-MPAL patients and compared clinical outcomes and safety between cytarabine, aclarubicin, and granulocyte colony-stimulating factor (CAG)-like regimens in 34 patients and conventional ALL regimens in 50 patients. In our series, ETP-ALL and T/M-MPAL showed similar biological characteristics, immunophenotypes, genomic alterations, and outcomes. The complete remission (CR) rate and minimal residual disease (MRD)-negative CR rate of CAG-like regimens were significantly higher compared with conventional ALL regimens (CAG-like: 80.0% and 59.7%, respectively; P = .039; ALL: 51.4% and 31.3%, respectively; P = .048). Overall, 90.0% of cases (18/20) achieved CR using combined decitabine and CAG-like regimens. Additionally, CAG-like regimens had lower rates of grade 3 or 4 infection (18.8% vs. 38.2%; P = .059) and grade 1 or 2 hepatotoxicity (37.5% vs. 60.0%; P = .043) than conventional ALL regimens. The 38 patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) in the first CR (CR1) had better overall survival (OS) and leukemia-free survival (LFS) than the 11 patients who underwent allo-HSCT in the second CR (CR2) or in no remission (median OS not reached vs. 7.6 months, P = .0004; median LFS not reached vs. 11.6 months, P = .0008). There was a significant difference in 3-year OS (95.7% vs. 52.5%; P = .0039) and LFS (95.8% vs. 43.5%; P = .0003) after allo-HSCT between pre-transplant MRD-negative and MRD-positive patients. The median OS for patients without allo-HSCT was 32.1 months in the CAG-like group compared with 12.1 months in the non-CAG-like group (P = .019). These findings suggest that ETP-ALL and T/M-MPAL possess overlapping characteristics and CAG-like regimens improve their clinical outcomes.

The genomic and biological complexity of mixed phenotype acute leukemia

Mixed phenotype acute leukemia (MPAL) is a heterogeneous group of leukemias that are defined immunophenotypically by antigen expression on blasts of both myeloid and lymphoid lineage. With the exception of BCR-ABL positive and KMT2A rearranged MPAL, the biology of the majority of MPAL remains uncertain. Several recent studies have explored the genomic and epigenetic landscape of MPAL and have suggested a further refinement of the WHO classification to emphasize the genomic heterogeneity of MPAL. Further studies including single cell analysis, whole exome sequencing and time of flight cytometry will provide for further biological characterization. Treatment decisions are complicated due to this lack of classification and the dearth of prospective randomized studies. Acute lymphoblastic leukemia-type therapy appears to achieve higher remission rates, and allogenic stem cell transplantation may be beneficial in a select group of patients in first complete remission. Multi-center collaborations may answer these questions more conclusively. Our review aims to discuss the diagnostic challenges, recent genomic studies and therapeutic strategies in this poorly understood disease.

Secondary donor-derived humanized CD19-modified CAR-T cells induce remission in relapsed/refractory mixed phenotype acute leukemia after allogeneic hematopoietic stem cell transplantation: a case report

Background

Mixed phenotype acute leukemia (MPAL) is a rare leukemia and is regarded as a high-risk entity with a poor prognosis. Induction therapy of an acute lymphoblastic leukemia type or hybrid regimen and hematopoietic stem cell transplantation has been recommended for MPAL. However, the optimal therapies for relapsed or refractory MPAL remain unclear, especially for relapse after stem cell transplantation. Donor-derived chimeric antigen receptor T (CAR-T) cell therapy may be a promising therapeutic option for patients with MPAL who express target antigens and have relapsed after stem cell transplantation. However, recurrence remains a challenge, and reinfusion of CAR-T cells is not always effective. An infusion of secondary donor-derived humanized CD19-modified CAR-T cells may be effective in inducing remission.

Case presentation

We report a case of MPAL with CD19 expression. The patient was treated with acute lymphoblastic leukemia-like induction and consolidation therapies but remained positive for SET-NUP214 fusion gene transcript. He subsequently underwent a haploidentical stem cell transplantation but relapsed within 6 months. He then underwent donor-derived CD19-targeted CAR-T cell therapy and achieved a sustained, complete molecular remission. Unfortunately, he developed a CD19-positive relapse after 2 years. Donor-derived humanized CD19-directed CAR-T cells induced a second complete molecular remission without severe cytokine release syndrome or acute graft-versus-host disease.

Conclusion

This case demonstrated the efficacy and safety of humanized donor-derived CD19-modified CAR-T cell infusion for treating the recurrence of MPAL previously exposed to murine-derived CD19-directed CAR-T cells.

Favorable outcomes of acute leukemias of ambiguous lineage treated with hyperCVAD: a multi-center retrospective study

Acute leukemias of ambiguous lineage (ALAL) are rare hematologic malignancies with poor outcomes. Retrospective studies have suggested that acute lymphoblastic leukemia (ALL) regimens are more effective than acute myeloid leukemia (AML) regimens. We retrospectively examined the effectiveness of the widely-used adult ALL regimen hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone (hyperCVAD) as initial therapy in patients with ALAL at five academic institutions. Twenty-five patients were identified, including 23 with mixed phenotype acute leukemia (MPAL) and two with acute undifferentiated leukemia. Five of 8 tested (63%) had FLT3-ITD and 3 of 25 (12%) were Philadelphia chromosome-positive. The complete remission (CR) rate was 76%, with CR with incomplete count recovery (CRi) in an additional 8%, for an overall response rate of 84%. Median number of cycles to CR/CRi was 1. There were no deaths in the first 30 days. Of the 21 patients achieving CR or CRi, 14 (66%) proceeded to allogeneic hematopoietic stem cell transplantation. With a median follow-up time of 31.6 months, median overall survival for the entire cohort was not reached, and the estimated 2-year survival was 63%. HyperCVAD can be considered an effective and tolerable front-line regimen for patients with ALAL, and warrants further prospective study.

Optimal therapeutic strategies for mixed phenotype acute leukemia

PURPOSE OF REVIEW

Mixed phenotype acute leukemia (MPAL) encompasses a rare group of clinically, immunophenotypically, and genetically diverse leukemias. Diagnosing and treating these patients remains challenging. In recent years, systematic efforts have been made to better define the genetic landscape of MPAL. These insights allow better understanding of the pathophysiology of MPAL, have the potential for a more biologically meaningful classification and may promote targeted, novel approaches to treat these leukemias.

RECENT FINDINGS

Recent studies suggest that MPALs originate in a multipotent primitive cell, demonstrate large genetic diversity and include subgroups that may benefit from targeted therapy. Recent data support the use of ALL-type induction followed by allogeneic stem cell transplantation in first remission for most adults. Novel targeted approaches hold promise for treatment of MPAL; however, some may unpredictably select for clonal expansion of cells from a different lineage than observed at presentation.

SUMMARY

A biologically and genetically driven classification of MPAL may yield more accurate prognosis and potentially direct therapy in patients with MPAL. Prospective efforts that incorporate targeted approaches based on genetics and immunophenotype are warranted.

Significance of minimal residual disease in pediatric mixed phenotype acute leukemia: a multicenter cohort study

The rarity of mixed phenotype acute leukemia (MPAL) has precluded adequate data to incorporate minimal residual disease (MRD) monitoring into therapy. Fluidity in MPAL classification systems further complicates understanding its biology and outcomes; this includes uncertainty surrounding the impact of shifting diagnostic requirements even between iterations of the World Health Organization (WHO) classification. Our primary objective was to address these knowledge gaps. To do so, we analyzed clinicopathologic features, therapy, MRD, and survival in a centrally-reviewed, multicenter cohort of MPAL uniformly diagnosed by the WHO classification and treated with acute lymphoblastic leukemia (ALL) regimens. ALL induction therapy achieved an EOI MRD negative (<0.01%) remission in most patients (70%). EOI MRD positivity was predictive of 5-year EFS (HR = 6.00, p < 0.001) and OS (HR = 9.57, p = 0.003). Patients who cleared MRD by EOC had worse survival compared with those EOI MRD negative. In contrast to adults with MPAL, ALL therapy without transplantation was adequate to treat most pediatric patients. Earlier MRD clearance was associated with better treatment success and survival. Prospective trials are now necessary to validate and refine MRD thresholds within the pediatric MPAL population and to identify salvage strategies for those with poor predicted survival.

Concomitant use of blinatumomab and donor lymphocyte infusion for mixed-phenotype acute leukemia: a case report with literature review

Blinatumomab and donor lymphocyte infusion (DLI) combination is a promising cancer therapy, whereby blinatumomab might achieve an initial reduction in leukemic-cell burden using T cells, and after tumor clearance, DLI can potentially stimulate the donor immune system to achieve longer lasting remission. Here, we present a 51-year-old female with mixed phenotype acute leukemia who had a hematologic relapse 3 months after she received total body irradiation-based myeloablative allogeneic hematopoietic stem cell transplantation from an unrelated human leukocyte antigen matched (10/10) donor and achieved complete remission with minimal residual disease negativity by multi-parameter flow cytometry using the combination of blinatumomab and DLI. To the best of our knowledge, this is the first report to describe the use of blinatumomab and DLI combination therapy in the treatment of B/myeloid mixed phenotype acute leukemia.

Integrin α7 and Extracellular Matrix Laminin 211 Interaction Promotes Proliferation of Acute Myeloid Leukemia Cells and Is Associated with Granulocytic Sarcoma

Acute myeloid leukemia (AML) with granulocytic sarcoma (GS) is characterized by poor prognosis; however, its underlying mechanism is unclear. Bone marrow samples from 64 AML patients (9 with GS and 55 without GS) together with AML cell lines PL21, THP1, HL60, Kasumi-1, and KG-1 were used to elucidate the pathology of AML with GS. RNA-Seq analyses were performed on samples from seven AML patients with or without GS. Gene set enrichment analyses revealed significantly upregulated candidates on the cell surface of the GS group. Expression of the adhesion integrin α7 (ITGA7) was significantly higher in the GS group, as seen by RT-qPCR (p = 0.00188) and immunohistochemistry of bone marrow formalin-fixed, paraffin-embedded (FFPE) specimens. Flow cytometry revealed enhanced proliferation of PL21 and THP1 cells containing surface ITGA7 in the presence of laminin 211 and stimulated ERK phosphorylation; this effect was abrogated following ITGA7 knockdown or ERK inhibition. Overall, high ITGA7 expression was associated with poor patient survival (p = 0.0477). In summary, ITGA7 is highly expressed in AML with GS, and its ligand (laminin 211) stimulates cell proliferation through ERK signaling. This is the first study demonstrating the role of integrin α7 and extracellular matrix interactions in AML cell proliferation and extramedullary disease development.

Acute Leukemias of Ambiguous Lineage: Clarification on Lineage Specificity

Acute leukemias of ambiguous lineage (ALAL) include acute undifferentiated leukemia and mixed-phenotype acute leukemia (MPAL). This article provides an overview of the diagnosis of ALAL and focuses on the data accounting for the current lineage-assignment criteria for blasts harboring more than one lineage-associated marker. In addition, the currently known molecular data are reviewed, which show that MPAL-associated gene mutations, methylation signatures, and expression profiles are a mixture of those seen in both acute myeloid leukemia and acute lymphoblastic leukemia. Finally, the prognosis and current treatments of MPAL are briefly discussed.

Refined Disease Risk Index for Hematological Malignancies, Including Rare Disorders, After Allogeneic Stem Cell Transplantation

OBJECTIVE

The refined disease risk index (R-DRI) is a well-designed prognostic parameter that is based on only the disease type and status and is used for stratifying patients undergoing allogeneic hematopoietic stem cell transplantation (allo HSCT) into 4 risk groups. However, the application of the R-DRI for rare diseases has remained unclear.

METHODS

We evaluated 135 patients who underwent allo HSCT for hematological malignancies including rare diseases, such as acute leukemia of ambiguous lineage, acute T-cell leukemia/lymphoma, extranodal natural killer T-cell lymphoma, and lymphoblastic lymphoma, at our institute.

RESULTS

According to the R-DRI, overall survival (OS) and progression-free survival at 2 years for patients with the low, intermediate, high, and very high groups were 66.7% and 66.7%, 60.8% and 56.0%, 27.1% and 23.7%, and 5.9% and 5.1%, respectively (P < .0001 and P < .0001, respectively). OS showed no significant difference between B-cell non-Hodgkin lymphoma (B-NHL) and T-cell non-Hodgkin lymphoma (T-NHL) (P = .71). Moreover, OS at 1 year was 80%, 14.3%, 60%, and 0% for the intermediate risk group, the very high-risk group of B-NHL, the intermediate risk group, and the high-risk group of T-NHL, respectively (P = .035).

CONCLUSION

We showed the applicability of the R-DRI for hematological malignancies, including rare disorders. However, we suggest that T-NHL patients may be better to be assigned between the nodal group and the extranodal group in the R-DRI.

Mixed-phenotype acute leukemia: A cohort and consensus research strategy from the Children's Oncology Group Acute Leukemia of Ambiguous Lineage Task Force

BACKGROUND

Optimal chemotherapy for treating mixed-phenotype acute leukemia (MPAL) and the role of hematopoietic stem cell transplantation (HSCT) remain uncertain. Major limitations in interpreting available data are MPAL's rarity and the use of definitions other than the currently widely accepted criteria: the World Health Organization 2016 (WHO2016) classification.

METHODS

To assess the relative efficacy of chemotherapy types for treating pediatric MPAL, the Children's Oncology Group (COG) Acute Leukemia of Ambiguous Lineage Task Force assembled a retrospective cohort of centrally reviewed WHO2016 MPAL cases selected from banking studies for acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Patients were not treated in COG trials; treatment and outcome data were captured separately. The findings were then integrated with the available, mixed literature to develop a prospective trial in pediatric MPAL.

RESULTS

The central review confirmed that 54 of 70 cases fulfilled WHO2016 criteria for MPAL. ALL induction regimens achieved remission in 72% of the cases (28 of 39), whereas AML regimens achieved remission in 69% (9 of 13). The 5-year event-free survival (EFS) and overall survival (OS) rates for the entire cohort were 72% ± 8% and 77% ± 7%, respectively. EFS and OS were 75% ± 13% and 84% ± 11%, respectively, for those receiving ALL chemotherapy alone without HSCT (n = 21).

CONCLUSIONS

The results of the COG MPAL cohort and a literature review suggest that ALL chemotherapy without HSCT may be the preferred initial therapy. A prospective trial within the COG is proposed to investigate this approach; AML chemotherapy and/or HSCT will be reserved for those with treatment failure as assessed by minimal residual disease. Embedded biology studies will provide further insight into MPAL genomics.