Peripheral blood marker of residual acute leukemia after hematopoietic cell transplantation using multi-plex digital droplet PCR. 

 -  2022 
<br/><br/> Background: Relapse remains the primary cause of death after hematopoietic cell transplantation (HCT) for acute leukemia. The ability to identify minimal/measurable residual disease (MRD) via the blood could identify patients earlier when immunologic interventions may be more successful. We evaluated a new test that could quantify blood tumor mRNA as leukemia MRD surveillance using droplet digital PCR (ddPCR).  Methods: The multiplex ddPCR assay was developed using tumor cell lines positive for the tumor associated antigens (TAA: WT1, PRAME, BIRC5), with homeostatic ABL1. On IRB-approved protocols, RNA was isolated from mononuclear cells from acute leukemia patients after HCT (n = 31 subjects; n = 91 specimens) and healthy donors (n = 20). ddPCR simultaneously quantitated mRNA expression of WT1, PRAME, BIRC5, and ABL1 and the TAA/ABL1 blood ratio was measured in patients with and without active leukemia after HCT.  Results: Tumor cell lines confirmed quantitation of TAAs. In patients with active acute leukemia after HCT (MRD+ or relapse; n=19), the blood levels of WT1/ABL1, PRAME/ABL1, and BIRC5/ABL1 exceeded healthy donors (p<0.0001, p=0.0286, and p=0.0064 respectively). Active disease status was associated with TAA positivity (1+ TAA vs 0 TAA) with an odds ratio=10.67, (p=0.0070, 95% confidence interval 1.91 - 59.62). The area under the curve is 0.7544. Changes in ddPCR correlated with disease response captured on standard of care tests, accurately denoting positive or negative disease burden in 15/16 (95%). Of patients with MRD+ or relapsed leukemia after HCT, 84% were positive for at least one TAA/ABL1 in the peripheral blood. In summary, we have developed a new method for blood MRD monitoring of leukemia after HCT and present preliminary data that the TAA/ABL1 ratio may may serve as a novel surrogate biomarker for relapse of acute leukemia after HCT. Copyright © 2022 Stanojevic, Grant, Vesely, Knoblach, Kanakry, Nazarian, Panditharatna, Panchapakesan, Gress, Holter-Chakrabarty and Williams. 
<br/><br/><br/>English 
<br/><br/><label>ISSN: </label>1664-3224 
<br/><br/><label>Standard No.: </label>10.3389/fimmu.2022.999298 [doi] PMC9556966 [pmc] 
<br/><br/><label>Subjects--Topical Terms: </label><br/>*Hematopoietic Stem Cell Transplantation<br/>*Leukemia, Myeloid, Acute<br/>Biomarkers<br/>Disease Progression<br/>Hematopoietic Stem Cell Transplantation/mt [Methods]<br/>Humans<br/>Leukemia, Myeloid, Acute/di [Diagnosis]<br/>Leukemia, Myeloid, Acute/ge [Genetics]<br/>Leukemia, Myeloid, Acute/th [Therapy]<br/>Neoplasm, Residual/ge [Genetics]<br/>Polymerase Chain Reaction/mt [Methods]<br/>Recurrence<br/>RNA<br/>RNA, Messenger
<br/><br/><label>Index Terms--Occupation: </label><br/>MedStar Georgetown University Hospital/MedStar Washington Hospital Center<br/>Pediatrics Residency
<br/><br/><label>Index Terms--Function: </label><br/>Journal Article