Richter’s syndrome: Comparing outcomes of two types of stem cell transplants

This study compared outcomes of two types of stem cell transplants (autologous and allogeneic) for Richter’s syndrome (transformed CLL). Authors reported a significant survival benefit following both types of stem cell transplant.

Chronic lymphocytic leukemia is a cancer of the blood and bone marrow. It has been estimated that in 2 to 8% of cases, chronic lymphocytic leukemia transforms into Richter’s syndrome (RS). RS is a fast-growing type of lymphoma that calls for intensive treatment early on.

Stem cell transplantation (also known as bone marrow transplant) is being explored as a treatment option for RS. Stem cells are immature blood cells that can be found in the bone marrow. They can be removed and stored from either the patient (autologous) or a donor (allogeneic). An autologous transplant involves harvesting stem cells from the patient’s blood or bone marrow. This is usually done before treatment such as chemotherapy or radiation that harm them. In an allogeneic transplant, stem cells come from a donor whose tissue type closely matches the patient’s. The process of the transplanted stem cells starting to make blood cells is called engraftment. Which type of transplant provides the most benefit for RS patients is still being investigated.

The aim of this study was to directly compare outcomes of the two types of stem cell transplants for RS.

The records of 59 RS patients were analyzed. 34 patients had received an autologous transplant (AUTO group). 25 patients received an allogeneic transplant (ALLO group). 36% of the ALLO group were no longer responding to chemotherapy. 72% of patients in the ALLO group were treated with chemotherapy at a lower intensity (known as reduced-intensity conditioning).

Engraftment was achieved in 92% of patients in the ALLO group and in 97% of patients in the AUTO group. Blood counts started to recover after an average of 15 days following ALLO. This was 18 days for AUTO.

3-year overall survival rate (proportion who have not died from any cause since treatment) was 36% in the ALLO group and 59% in the AUTO group. 26% of patients in the ALLO group died from complications related to the transplant at 3 years. This was 12% for AUTO patients. Causes included organ failure, infection, and the transplant attacking the recipient.

12 patients relapsed after ALLO. Of these, 10 relapsed with RS and 2 relapsed with chronic lymphocytic leukemia. 27% of ALLO patients were recurrence-free at 3 years. 17 patients relapsed after AUTO. Of these, 11 relapsed with RS and 6 relapsed with chronic lymphocytic leukemia. 45% of AUTO patients were recurrence-free at 3 years.

In the ALLO group, patients still responsive to chemotherapy and patients treated with reduced-intensity conditioning were associated with significantly lower disease recurrence rates. Factors that significantly affected AUTO treatment could not be identified.

Authors concluded that both autologous and allogeneic stem cell transplants can be effective for RS. Treatment may be less effective for patients no longer responding to chemotherapy.

Larger trials are needed to confirm these results.