Stem cell transplantation in follicular lymphoma

This study reviewed the use of stem cell (immature blood cell) transplantation in follicular lymphoma.

New treatment options have improved survival in follicular lymphoma patients. Improvements in stem cell transplantation (SCT) have also led to increased survival. Typically only younger patients have been able to tolerate the high-dose chemotherapy needed before SCT. Reducing the intensity of the chemotherapy (RIC) can allow older patients to undergo transplantation as well. The role of SCT now that rituximab (Rituxan) is a standard treatment option needs further study.

This study reviewed the role of SCT in the era of rituximab.

SCT is generally considered for patients who have relapsed or who did not respond to treatment. Stem cells can be harvested from the patient. This is known as autologous SCT (ASCT). Stem cells can also come from someone with a similar genetic profile. This could include a sibling or a matched donor. This is known as allogeneic SCT (allo-SCT). ASCT is the standard for more aggressive follicular lymphoma. Two studies of patients already treated with rituximab found no significant difference in survival following ASCT or allo-SCT.

Certain factors are associated with outcomes after SCT. Younger patients tend to respond better to SCT. Patients who are still sensitive to chemotherapy also tend to respond better. Chemotherapy is delivered before SCT to decrease cancer activity before transplantation. One study found that 45.5% of patients with cancer activity before SCT were progression free after 3 years. In comparison, 72.6% of those without cancer activity were progression free.

Most trials examining ASCT were conducted before rituximab was a standard first-line treatment. One trial examined the use of rituximab as a maintenance (long-term) therapy after SCT. Treated patients had lower rates of disease progression over 10 years (37%) compared to untreated patients (54%). Another study examined patients with prior rituximab treatment. Three-year survival was 87%.

Allo-SCT is now often combined with lower intensity conditioning (RIC). RIC-allo-SCT has been found to lead to similar progression and survival rates. Patients treated with RIC tend to be older and more heavily pretreated (including with rituximab).

Few studies have directly compared ASCT and RIC-allo-SCT, particularly in patients already treated with rituximab. One analysis combined the results of two trials (including 518 patients). This study reported that patients who underwent ASCT had higher survival rates, but were more likely to relapse or progress. Direct comparisons are difficult, because RIC-allo-SCT patients often have higher risk features.

SCT has been associated with the development of second cancers, particularly blood cancers. One study found a 21% rate of second cancer after 15 years. No significant differences in second cancer rates have been found between the two types of SCT.

This study reviewed the use of SCT in follicular lymphoma. The authors noted that further studies are needed. These studies should examine the timing and type of SCT used in patients who have been treated with rituximab.