Long-term outcomes of allogeneic stem cell transplantations in young high-risk CLL patients

This study examined predictors of outcomes with stem cell transplantation from a donor (allo-SCT) for chronic lymphocytic leukemia (CLL). Researchers reported good long-term outcomes for young high-risk CLL patients treated with allo-SCT. Patients with matched sibling donors showed better outcomes compared to those with matched unrelated donors.

Targeted therapy is a first-line treatment for newly diagnosed CLL. This refers to a type of treatment that uses drugs or small molecules that block the growth and spread of cancer, such as kinase- and BCL2-inhibitors. However, outcomes for high-risk patients are often poor. This includes patients with genetic abnormalities (making CLL more difficult to treat) and for CLL that has relapsed or is refractory (no longer responding to standard therapy).

Allogeneic stem cell transplantation (allo-SCT) after high-dose chemotherapy is a more effective option for high-risk patients. This is when blood-forming cells destroyed by chemotherapy are replaced with stem cells (immature cells) from the blood or bone marrow of a donor. The main drawback of allo-SCT is the occurrence deaths without signs of relapse (knows as non-relapse mortality), which is highest within the first 2 years. Therefore, allo-SCT is particularly considered in younger high-risk CLL patients.

The aim of this study was to examine predictors of allo-SCT outcomes in young CLL patients.

The records of 197 CLL patients aged younger than 50 years were analyzed. Patients had a genetic abnormality (such as del 17p and del 11q) and/or relapsed or refractory disease. All patients underwent allo-SCT. The average follow-up was 90.4 months.

At 2 years, 55% of patients were progression-free. At 8 years, it was 38%. This result was not affected by the presence of genetic abnormalities. The 2-year overall survival rate (proportion who have not died from any cause since treatment) was 72%. The 8-year overall survival rate was 52%. Non-relapse mortality was 20% at 2 years and 23% at 8 years.

Patients who were not in remission at the time of allo-SCT were 70% more likely to show disease progression at 8 years. Patients who underwent allo-SCT from an unrelated donor were 2.8 times more likely to show disease progression at 8 years. They were also 4 times more likely to die within 2 years without signs of relapse compared to patients who underwent allo-SCT from a sibling donor. 

This study reported good long-term outcomes for young CLL patients treated with allo-SCT, especially when matched sibling donors were used. The authors of this study recommended the use of allo-SCT in young high-risk patients over the use of kinase- and BCL2-inhibitors.