EMMANUELLE CLAPPIER (PARIS)
MRD MONITORING IN PH-POSITIVE ALL
Dept. d’Hématologie, Hôpital Saint-Louis, Paris, France
Ig/TCR-based minimal residual disease (MRD) is a faithful marker of treatment response and the
strongest predictor of relapse in Ph-negative ALL. In adult Ph+ ALL, MRD is commonly monitored by
BCR-ABL1 transcript quantification. Recently, several studies revealed that BCR-ABL1 rearrangement
may be found in non-lymphoblastic cells in de novo Ph+ ALL patients. This came up by i) MRD
monitoring on both BCR-ABL1 and Ig/TCR rearrangement showing discordant patterns of responses
(1-3), and ii) myeloid switch of Ph+ ALL after blinatumomab treatment (4). These observations have
strong relevance for interpretation of MRD results and treatment decisions.
1. Hovorkova L, Zaliova M, Venn NC, Bleckmann K, Trkova M, Potuckova E, et al. Monitoring of childhood
ALL using BCR-ABL1 genomic breakpoints identifies a subgroup with CML-like biology. Blood
2017;129(20):2771‑81.
2. Cazzaniga G, De Lorenzo P, Alten J, Röttgers S, Hancock J, Saha V, et al. Predictive value of MRD in Ph+
ALL treated with imatinib in the EsPhALL study, based on IG/TR and BCR/ABL1 methodologies.
Haematologica 2017.
3. Clappier E, Kim R, Cayuela JM, Rousselot P, Chalandon Y, Passet M, et al. Persistent BCR-ABL1 clonal
hematopoiesis after blast clearance identifies a CML-like subgroup of patients with Philadelphia
chromosome-positive (Ph+) ALL: interim results from the GRAAPH-2014 trial. EHA 2018 Annual Meeting
Abstract.
4. Nagel I, Bartels M, Duell J, Oberg H-H, Ussat S, Bruckmueller H, et al. Hematopoietic stem cell
involvement in BCR-ABL1-positive ALL as a potential mechanism of resistance to blinatumomab therapy.
Blood 2017;130(18):2027‑31.