Multigene Measurable Residual Disease Assessment Improves Acute Myeloid Leukemia Relapse Risk Stratification in Autologous Hematopoietic Cell Transplantation

Abstract

We report here the largest study to date of adult AML patients tested for measurable residual disease (MRD) at the time of autologous hematopoietic cell transplantation (auto-HCT). Seventy-two adult patients transplanted between 2004–2013 at a single academic medical center (UCSF) were eligible for this retrospective study based on availability of cryopreserved GCSF mobilized autologous peripheral blood progenitor cell (PBPC) leukapheresis specimens (“autografts”). Autograft MRD was assessed by molecular methods (RQ-PCR for WT1 alone or a multigene panel) and by multi-parameter flow cytometry (MPFC). WT1 RQ-PCR testing of the autograft had low sensitivity for relapse prediction (14%) and a negative predictive value of 51%. MPFC failed to identify MRD in any of 34 autografts tested. Combinations of molecular MRD assays however improved prediction of post auto-HCT relapse. In multivariate analysis of clinical variables, including age, gender, race, cytogenetic risk category, and CD34+ cell dose, only autograft multigene MRD as assessed by RQ-PCR was statistically significantly associated with relapse. One year after transplantation only 28% patients with detectable autograft MRD were relapse free, compared with 67% in the MRD negative cohort. Multigene MRD, while an improvement on other methods tested, was however suboptimal for relapse prediction in unselected patients with specificity of 83% and sensitivity of 46%. In patients with known chromosomal abnormalities or mutations, however, better predictive value was observed with no relapses observed in MRD negative patients in the first year after auto-HCT compared with 83% incidence of relapse in the MRD positive patients (HR 12.45, p=0.0016). In summary, increased personalization of MRD monitoring by use of a multigene panel improved the ability to risk stratify patients for post auto-HCT relapse. WT1 RQ-PCR and flow cytometric assessment for AML MRD in autograft samples had limited value for predicting relapse following auto-HCT. We demonstrate that cryopreserved autograft material presents unique challenges for AML MRD testing due to masking effects of previous GCSF exposure on gene expression and flow cytometry signatures. In the absence of information regarding diagnostic characteristics, sources other than GCSF-stimulated PBSC leukapheresis specimens should be considered as alternatives for MRD testing in AML patients undergoing auto-HCT.

The Role of Measurable Residual Disease (MRD) in Hematopoietic Stem Cell Transplantation for Hematological Malignancies Focusing on Acute Leukemia

“…Autologous transplantation can potentially allow a selected group of patients, especially with low and potentially intermediate genetic risk, to avoid over-treatment with allogeneic transplantation, providing 50–60% probability of long-term LFS [74]. The recently published excellent outcomes of autologous transplantation in MRD negative patients with low or intermediate genetic risk [75,76,77,78] prompt re-evaluating the role of autologous transplantation in AML. In this regard, a group from China compared retrospectively autologous to allogeneic HSCT in AML patients with favorable or intermediate genetic risk [76].…”

Bone marrow evaluation for diagnosis and monitoring of acute myeloid leukemia

“…This limitation may be mitigated, in part, by using a multiple gene approach as studied in patients receiving allogeneic HCT 59,100 and autologous HCT. 101 Though sampling of peripheral blood every three months is typically used for monitoring, different molecular aberrations may require more frequent testing or even bone marrow sampling, due to distinct differences in the doubling time of abnormal clones. 102,103 …”

Technical Advances in the Measurement of Residual Disease in Acute Myeloid Leukemia

“…While the most recent response criteria for AML now does include a category of MRD-negative CR [ 10 ], there is no single standard technique for such sensitive detection; real-time quantitative PCR (qPCR) for overexpressed genes [ 11 , 12 ] or pathognomonic chromosomal translocations [ 13 ], fluorescence in situ hybridization (FISH) [ 14 ], and multiparameteric flow cytometry [ 15 ] are all possible detection strategies. Regardless of the MRD detection methodology used, it is widely appreciated that MRD positivity (MRD + ) in cytomorphological CR portends a higher cumulative risk of subsequent clinically evident relapse.…”