Mixed-phenotype acute leukemia: state-of-the-art of the diagnosis, classification and treatment

Low subcutaneous adipose tissue and myosteatosis are prognostic factors after allogeneic hematopoietic stem cell transplantation

OBJECTIVE

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) represents the only curative treatment option for several hematological neoplasms. This study aimed to assess the parameters of body composition as predictors of post-transplant overall survival (OS) and adverse events in patients with leukemia, myelodysplastic syndromes (MDS), and myeloproliferative neoplasms (MPN).

METHODS

This was a retrospective study of 122 adult patients who underwent their first allo-HSCT. The CT-based semi-automated measurement of subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), visceral-to-subcutaneous fat ratio (VSR), sarcopenia in terms of skeletal muscle index (SMI), and myosteatosis based on the skeletal muscle radiation attenuation (SM-RA) was performed. Cox regression analysis was used to assess the association of body composition parameters with OS.

RESULTS

In the univariate analysis, low SAT and myosteatosis were associated with lower OS (hazard ratio [HR] 2.02, 95% confidence interval [CI] 1.16-3.51, p = 0.01) and (HR 2.50, 95% CI 1.48-4.25, p =< 0.001), respectively. This association remained significant after adjusting for relevant covariates, with HR 2.32, 95% CI 1.23-4.38, p = 0.01 and HR 2.86, 95% CI 1.51-5.43, p =< 0.001, respectively. On the contrary, VAT, VSR, sarcopenia, and sarcopenic obesity were not statistically significant in OS. Severe post-transplant adverse events were more common in the low SAT group (odds ratio [OR] 3.12, 95% CI 1.32-7.40, p = 0.01) and OR 3.17, 95% CI 1.31-7.70, p =< 0.01 in the age- and sex-adjusted analysis.

CONCLUSION

Low SAT and myosteatosis may contribute to an increased risk of post-transplant mortality, while low SAT appears to increase the risk of severe post-transplant adverse events.

Multilineage Lymphoblastic Lymphoma as an Initial Presentation of Mixed Phenotype Acute Leukemia

Mixed phenotype acute leukemia (MPAL) is characterized by leukemic blasts that express markers of multiple lineages. Compared with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL), MPAL is considered to have a poor treatment outcome. We report a case of MPAL T/myeloid not otherwise specified that was initially presented as multilineage lymphoblastic lymphoma and subsequently developed into leukemic MPAL. An acute lymphoblastic leukemia-based treatment regimen was ineffective, but azacitidine and venetoclax therapy resulted in hematological complete remission. Our case suggests that multilineage lymphoblastic lymphoma should be considered to be the same disease as MPAL, albeit with different clinical presentations. Optimal treatment for MPAL has not been established yet, but azacitidine and venetoclax therapy may be a potential approach.

Characteristics, Treatment Complexity, and Outcome of Mixed-Phenotype Acute Leukemia in Children in a Low–Middle-Income Country

Background

Mixed-phenotype acute leukemia (MPAL) in children is an uncommon subtype of acute leukemia that cannot be definitively assigned to a specific lineage. There is no consensus on the best approach to therapy. Management is more complex in low–middle-income countries (LMICs).

Aim

To evaluate the clinicopathological characteristics and outcomes of patients with MPAL in a developing country.

Patients and Methods

A retrospective descriptive study of 42 pediatric patients newly diagnosed with MPAL from July 2007 until December 2017.

Results

The immunophenotyping was T/Myeloid in 24 patients (57.1%) and B/Myeloid in 16 (38.1%). Three subjects had MLL gene rearrangement, two had Philadelphia-positive chromosomes, and eight had FMS-like tyrosine kinase 3 (FLT3-ITD) internal tandem duplication (FLT3-ITD) with a ratio &gt;0.4. Two subjects died before starting chemotherapy. Ten patients (25%) received acute lymphoblastic leukemia (ALL) induction, and all achieved complete remission (CR) with no induction deaths and no shift of therapy. Thirty patients (75%) started therapy with acute myeloid leukemia (AML) induction: five (16.6%) died during induction, 17 (56.7%) achieved CR, and 10 patients received maintenance ALL therapy after ending AML treatment. Four of the eight patients with induction failure were switched to ALL therapy. The 5-year event-free survival (EFS) and overall survival (OS) rates were 56.7% [standard error (SE): 8.1%] and 61% (SE: 8%), while the cumulative incidence of relapse was 21.7% (SE: 6.7%), with a median follow-up duration of 5.8 years. Patients treated with ALL-directed therapy had a 5-year EFS rate of 111 70% (SE: 14%) and OS rate of 78.8% (SE: 13%). Patients treated with ALL-directed therapy had a 5-year EFS rate of 70% (SE: 14.5%) and OS rate of 78.8% (SE: 13%). FLT3-ITD mutation showed a significantly lower 5-year EFS rate of 28.6% (SE: 17%) vs. 75% (SE: 9%) for the wild type, p = 0.032. Undernourished patients with a body mass index (BMI) z-score ≤-2 at presentation had a significantly lower 5-year EFS rate of 20% (SE: 17%) compared to 61.8% (SE: 8%) for patients with BMI z-score &gt;-2, p = 0.015.

Conclusion

This study supports ALL-directed therapy for pediatric MPAL in a setting of LMIC. Given the poor outcome of FLT3-ITD, the role of FLT3 inhibitor needs to be explored in this subset of cases.

Zebrafish B cell acute lymphoblastic leukemia: new findings in an old model

Acute lymphoblastic leukemia (ALL) is the most common pediatric, and ninth most common adult, cancer. ALL can develop in either B or T lymphocytes, but B-lineage ALL (B-ALL) exceeds T-ALL clinically. As for other cancers, animal models allow study of the molecular mechanisms driving ALL. Several zebrafish (Danio rerio) T-ALL models have been reported, but until recently, robust D. rerio B-ALL models were not described. Then, D. rerio B-ALL was discovered in two related zebrafish transgenic lines; both were already known to develop T-ALL. Here, we report new B-ALL findings in one of these models, fish expressing transgenic human MYC (hMYC). We describe B-ALL incidence in a large cohort of hMYC fish, and show B-ALL in two new lines where T-ALL does not interfere with B-ALL detection. We also demonstrate B-ALL responses to steroid and radiation treatments, which effect ALL remissions, but are usually followed by prompt relapses. Finally, we report gene expression in zebrafish B lymphocytes and B-ALL, in both bulk samples and single B- and T-ALL cells. Using these gene expression profiles, we compare differences between the two new D. rerio B-ALL models, which are both driven by transgenic mammalian MYC oncoproteins. Collectively, these new data expand the utility of this new vertebrate B-ALL model.

Simultaneous B and T cell acute lymphoblastic leukemias in zebrafish driven by transgenic MYC: implications for oncogenesis and lymphopoiesis

Precursor-B cell acute lymphoblastic leukemia (pre-B ALL) is the most common pediatric cancer, but there are no useful zebrafish pre-B ALL models. We describe the first highly- penetrant zebrafish pre-B ALL, driven by human MYC. Leukemias express B lymphoblast-specific genes and are distinct from T cell ALL (T-ALL)—which these fish also develop. Zebrafish pre-B ALL shares in vivo features and expression profiles with human pre-B ALL, and these profiles differ from zebrafish T-ALL or normal B and T cells. These animals also exhibit aberrant lymphocyte development. As the only robust zebrafish pre-B ALL model and only example where T-ALL also develops, this model can reveal differences between MYC-driven pre-B vs. T-ALL and be exploited to discover novel pre-B ALL therapies.