Mechanisms of extramedullary relapse in acute lymphoblastic leukemia Reconciling biological concepts and clinical issues

J. Gaudichon (1, 2) , H. Jakobczyk (1) , L. Debaize (1) , E. Cousin (1) , M.-D. Galibert (1, 3) , M.-B. Troadec (1, 3) , V. Gandemer (1, 3)

1 IGDR - Institut de Génétique et Développement de Rennes
2 CHU Caen
3 Centre Hospitalier Universitaire de Rennes [CHU Rennes] = Rennes University Hospital [Ponchaillou]

Long-term survival rates in childhood acute lymphoblastic leukemia (ALL) are currently above 85% due to huge improvements in treatment. However, 15-20% of children still experience relapses. Relapses can either occur in the bone marrow or at extramedullary sites, such as gonads or the central nervous system (CNS), formerly referred to as ALL-blast sanctuaries. The reason why ALL cells migrate to and stay in these sites is still unclear. In this review, we have attempted to assemble the evidence concerning the microenvironmental factors that could explain why ALL cells reside in such sites. We present criteria that make extramedullary leukemia niches and solid tumor metastatic niches comparable. Indeed, considering extramedullary leukemias as metastases could be a useful approach for proposing more effective treatments. In this context, we conclude with several examples of potential niche-based therapies which could be successfully added to current treatments of ALL.

Mots clés: Central nervous system; Cellular microenvironment; Bone marrow; Acute lymphoblastic leukemia; Extramedullary; Niche; Relapse; Testis; Sanctuary; Children

Domaines: Sciences du Vivant [q-bio]; Cancer

J. Gaudichon, H. Jakobczyk, L. Debaize, E. Cousin, M.-D. Galibert, et al.. Mechanisms of extramedullary relapse in acute lymphoblastic leukemia Reconciling biological concepts and clinical issues. Blood Reviews, 2019, 36, pp.40-56. ⟨10.1016/j.blre.2019.04.003⟩. ⟨hal-02132591⟩