AUTHOR=Tian Huohuan , Yang Linhui , Hou Wang , Wu Yu , Dai Yang , Yu Jiang , Liu Dan 

TITLE=Case report: Identification of acute promyelocytic leukemia during osimertinib resistance followed by granulocyte colony-stimulating factor and pembrolizumab

JOURNAL=Frontiers in Oncology

VOLUME=Volume 12 - 2022

YEAR=2023

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2022.1032225

DOI=10.3389/fonc.2022.1032225

ISSN=2234-943X

ABSTRACT=Background
The occurrence of acute promyelocytic leukemia (APL) during management of lung cancer is rare and life-threatening. It was mainly reported to be secondary to chemoradiotherapy. Few studies reported an increased incidence of therapy-related acute promyelocytic leukemia (t-APL), or after gefitinib available.
Case presentation
We reported a patient suffered from thrombocytopenia after oral Osimertinib in combination with intensive modulated radiotherapy (IMRT). She showed an unrecoverable low platelet count for half a year, which progressed to concomitant leukopenia, and transient appearance of orthochromatic normoblasts in the peripheral blood test, indicating a dormant myeloid disorder. Owing to simultaneous resistance of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), pembrolizumab and granulocyte colony-stimulating factor (G-CSF) were administered, unveiling prominent signs of hematological malignancy in peripheral blood test which was later identified as t-APL. 
Conclusion 
In general, patients undergoing EGFR-TKI combined with local radiotherapy should be concerned about hematological assessment. If patients exhibit unrecoverable abnormality in routine blood examination, secondary non-solid malignancy other than myelosuppression should be considered and further lung cancer treatment should be suspended.