Haploidentical stem cell transplant after failed autologous stem cell transplant: Lower risk of disease progression compared to identical-matched donors

This study examined the effect of donor type on allogeneic stem cell transplant outcomes in patients with relapsed Hodgkin lymphoma. This study reported reduced disease progression in patients with partially matched donors compared to identical matches. 

While Hodgkin lymphoma is a curable disease, some patients experience a disease relapse or they do not respond to treatment. These patients are treated with autologous stem cell transplantation (immature blood cells harvested from their own body).

Patients who relapse after autologous stem cell transplantation may undergo an allogeneic transplant. An allogeneic transplant requires patients to be matched with a donor, ideally someone with a similar genetic background (like a sibling). There is a higher chance of having the same human leukocyte antigens (HLA) when the donor is a close relative. An HLA identical stem cell transplantation (HLA-SCT) means that the patient’s and the donor’s tissues have similar antibodies and are more compatible. Some patients cannot find an identical match. Haploidentical stem cell transplantation (haplo-SCT) uses stem cells from a donor that is a 50% match.

The aim of this study was to compare HLA-SCT and haplo-SCT in patients relapsing after an autologous stem cell transplant.

The records of 64 patients were analyzed. All patients relapsed after autologous stem cell transplant. 34 patients underwent HLA-SCT. 30 patients underwent haplo-SCT with the chemotherapy cyclophosphamide (Cytoxan). Patients were followed for an average of 47 months.

All patients engrafted. This refers to the process of the stem cells starting to make new blood cells. The average time to engraftment was significantly shorter with HLA-SCT compared to haplo-SCT.

3-year overall survival rate (proportion who have not died from any cause since treatment) was 53%. Overall survival was similar between the two treatment groups. The mortality rate without any documented signs of relapse was 17% at 12 months. It was higher for haplo-SCT (26%) than for HLA-SCT (9%). However, this difference was not statistically significant.

44% of patients were progression-free at 3 years. Patients treated with haplo-SCT were significantly less likely to experience disease relapse compared to HLA-SCT. At 3 years, 13% of patients treated with haplo-SCT relapsed. It was 62% for patients treated with HLA-SCT. The rate of graft-versus-host disease (when donor cells attack the organs of the patient) was also lower for haplo-SCT (3%) than for HLA-SCT (32%).

Haplo-SCT reduced the risk of disease relapse by 83%. Achieving complete remission (no sign of active disease) reduced the risk of relapse by 40%. 

Researchers concluded that haplo-SCT with cyclophosphamide is an effective treatment option for relapsed Hodgkin lymphoma patients.

Since this study analyzed the records of patients already treated, factors that can affect treatment outcomes cannot be as easily controlled. Larger studies are needed to confirm these results.