Trial Information

Safety and Efficacy of a Strategy of Allogeneic Hematopoietic Stem Cell Transplantation After Reduced-intensity Conditioning for Chemosensitive Relapsed Follicular Lymphoma

Follicular lymphomas are chemosensitive neoplasms characterized by a relentless succession
of remissions and relapses when treated with conventional chemotherapy. The successive
periods of remission are of shorter duration and patients invariably die of their disease.
At first line, patients are treated with conventional chemotherapy. At first relapse,
intensive chemotherapy with autologous stem cell transplantation (SCT) is often proposed.

Allogeneic hematopoietic stem cell transplantation after reduced-intensity conditioning
(RIC-allo) is an option for patients relapsing after autologous SCT, allowing long-term
progression free survival of 50 to 60%. The toxic mortality related to severe acute graft
versus host disease (GVHD) remains a critical issue. The goal of our study is to test in a
multicentric approach a strategy of RIC-allo including rituximab in order to reduce the
incidence of acute GVHD.

Around half of patients with relapsed or refractory follicular lymphomas treated with
allogeneic SCT achieve long-term progression free survival whatever the conditioning
regimen. Because the median age of patients with follicular lymphoma is 55 years, a reduced
intensity conditioning is the most appropriate option in this setting. The outcome of
patients with a chemoresistant disease is usually poor because of a high toxic mortality. As
a consequence, only patients with a chemosensitive disease will be included in this study.
To further reduce the toxic mortality, it is critical to reduce the incidence of severe
acute GVHD. A low incidence of acute GVHD could be obtained by the use of Rituximab before
and after the transplantation as reported by the MD Anderson's experience in several
hematological malignancies including follicular lymphoma. Their results are impressive in
patients with follicular lymphoma with long-term survival of 85%. The favored hypothesis is
a depletion of patient and donor B cells reducing the presentation of minor
histocompatibility alloantigens. The benefit of Rituximab could also be explained by its
anti-lymphoma effects that could compensate the putative reduction of a graft versus
lymphoma effect due to a better control of GVHD.

The primary objective is to estimate 2-year overall survival in this setting.