INTRODUCTION

Mixed-phenotype acute leukemia (MPAL) is a diverse group of blood cancers where the leukemia cells have characteristics of multiple cell lineages and constitute 2-3% of all acute leukemias. MPAL is generally considered to have a poor prognosis.

OBJECTIVE

The present study highlighted the clinical, pathological, and survival outcomes of MPAL cases diagnosed in the National Cancer Center of Peru for 10 years.

METHODS

We conducted a retrospective observational study on 47 cases diagnosed with MPAL between 2012 and 2021. The diagnosis of MPAL was based on the World Health Organization (WHO) 2008 and 2016 classification. We used descriptive statistics to analyze categorical and continuous variables. Overall survival was analyzed by the Kaplan-Meier method and the differences according to characteristics by log-rank test.

RESULTS

There were 29 men and 18 women: with a median age of 35 years [range 21-54]. The median hemoglobin was 7.85 g/dl [7.25 - 9.25 g/dl]. The median total leukocyte count was 38.005 x 109/L [6.425 - 146.58 109/L]. The median platelet count was 45 × 109/L [17.75 - 104.25 109/L]. Immunophenotyping disclosed B + myeloid (n:35,74.5%), T + myeloid (n:7,14.9%), B + T (n:3, 6.4%), or trilineage (n:2,4.2%) combinations. Cytogenetics is performed on 26 patients, evidenced by t(9;22)/(Ph+) (23%), complex (23%), aberrant (7%), or normal (46%) karyotypes. Mutations are performed on 30 patients, BCR/ABL p190 or p210 mutations were performed in 40% of cases, FLT3 ITD in 6.7%, and MLL/AF4 in 3.3%. The most common cytogenetic abnormality in B/myeloid MPAL was translocation t (9;22).

Response to induction treatment was available in 29 patients, 19 received ALL, 10 AML, and ALL treatment induced a response in 42 %, with AML therapy in 50 %. Eighteen (38.3%) patients did not receive any treatment, 42 (89.3%) died, all except two died within the month since diagnosis, 4 (8.5%) underwent allogeneic stem cell transplants, and all of them were alive at the latest follow-up. The overall median survival was 10 months, and the five-year survival estimation was 12%. Leukocytosis > 30 x 109/L at diagnosis and non-complete response after induction therapy were predictors for poor outcomes (P =0.031; P= 0.022).

CONCLUSIONS

MPAL is a rare and high-risk disease. Patients should be considered for transplantation in their first remission. Unfortunately, we have lots of patients who die early without treatment.

Disclosures

No relevant conflicts of interest to declare.

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