ALLTogether recommendations for biobanking samples from patients with acute lymphoblastic leukaemia: a modified Delphi study.

Acute lymphoblastic leukaemia (ALL) is a rare and heterogeneous disease. The ALLTogether consortium has implemented a treatment protocol to improve outcome and reduce treatment-related toxicity across much of Europe. The consortium provides the opportunity to design translational research on patient material stored in national biobanks. However, there are currently no standardized guidelines for the types of material, processing, and storage for leukaemia biobanking. To address this gap, we conducted a modified Delphi survey among 53 experts in different roles related to leukaemia. The first round consisted of 63 statements asking for level of agreement. The second round refined some to reach consensus, using yes-no and multiple-option answers. Key recommendations include cryopreservation of cells from diagnosis, post-induction, post-consolidation, and relapse, with at least two aliquots of plasma and serum, and cerebrospinal fluid from diagnosis, day15, and post-induction. It was advised to distribute cells across multiple vials for various research projects, and to collect data on sample processing, cell viability, and blast percentage. Quality monitoring and user feedback were strongly recommended. The Delphi survey resulted in strong recommendations that can be used by national biobanks to harmonize storage of samples from patients with ALL and ensure high-quality cryopreserved cells for research studies.