Transmission of chronic lymphocytic leukaemia from a blood stem cell sibling donor to the recipient

The role of allogeneic hematopoietic cell transplantation for chronic lymphocytic leukemia: A review

Although the use of allogeneic hematopoietic cell transplantation (HCT) for chronic lymphocytic leukemia (CLL) has declined with the development of novel targeted agents, it continues to play an important role for eligible patients with high-risk or heavily pretreated CLL who lack other treatment options. CLL is susceptible to a potent graft-versus-leukemia (GVL) effect which produces long-lasting remissions in 30-50% of transplanted patients. While allogeneic HCT is associated with significant risks of graft-versus-host disease (GVHD), infection, and non-relapse mortality (NRM), improvements in patient and donor selection, reduced intensity conditioning (RIC), GVHD prophylaxis, and supportive care have rendered this an increasingly safe and effective procedure in the current era. In this review, we discuss recent advances in allogeneic HCT for CLL, with a focus on the optimal evidence-based strategies to maximize benefit and minimize toxicity of this potentially curative cellular therapy.

Monoclonal B cell lymphocytosis--what does it really mean?

Monoclonal B cell Lymphocytosis (MBL) or similar terms have been used for decades to describe the presence of light-chain restricted B lymphocytes with uncertain clinical significance, usually having a phenotype consistent with chronic lymphocytic leukemia (CLL). As diagnostic technology improved, ever smaller monoclonal B cell populations were identifiable in the population, and approximately half of people over 90 years old have a minimal (<1 cell/μL) circulating CLL-like B cell population. These minimal CLL-like B cell populations share some molecular characteristics with CLL, but have no clinical significance. In contrast, CLL-like MBL cases detected through hospital investigations are biologically indistinguishable from early stage CLL, but the neoplastic B cell levels are usually stable over time and the risk of progressive disease requiring treatment is much lower than for early stage CLL. However, there is usually partial or complete depletion of normal B cells, with an increased relative risk of severe infection, comparable to early stage CLL, which may impair overall survival.

Systematic donor blood qualification by flow cytometry would have been able to avoid CLL-type MBL transmission after unrelated hematopoietic stem cell transplantation

The current screening for eligibility of unrelated volunteer marrow donors comprises a complete clinical check-up, a blood CBC and serum protein immunoelectrophoresis. This allows to eliminate acute leukemias, myeloproliferative and myelodysplastic disorders, myelomas and MGUS. To date, the risk of transmission of chronic lymphocytic leukemia (CLL) disease is only evaluated by the clinical evaluation and CBC. We report here the case of a CLL-type MBL disease occurring in a 12-year-old boy after unrelated BMT. Deep biological investigations, as Immunophenotyping, cytogenetic and molecular biology allow us to determine the donor origin of the CLL clone. In 2010, 14.2% donor (105/737) for unrelated hematopoietic stem cell transplantation were over 45y. It is currently estimated (USA) that 1 in 210 men and women will be diagnosed with CLL during their lifetime. Given the long asymptomatic phase of CLL, this raises the case for a detection strategy analog to that used for MGUS and myeloma through serum protein electrophoresis. This case-report, to our knowledge, of a CLL-type MBL unrelated donor-to-recipient transmission through BMT raises ethical and practical questions, such as the proper information about disease transmission risk. The cost-effectiveness of a systematic peripheral blood Immunophenotyping in donors elder than 40y at time of stem cell donation should be evaluated.