Post-authorization Safety Study of Allogeneic Hematopoietic Stem Cell Transplantation in Patients Treated With Mogamulizumab

This study is tracking the safety of stem cell transplants (allogeneic hematopoietic stem cell transplantation) in patients who previously received a drug called mogamulizumab for certain blood cancers, including cutaneous T-cell lymphoma (CTCL) and adult T-cell leukemia/lymphoma (ATLL). The concern is whether mogamulizumab affects how well the body tolerates a subsequent transplant. **You may be eligible if...** - You are 18 or older - You have CTCL (skin lymphoma) or ATLL (an aggressive blood cancer) - You received a stem cell transplant from a donor (allogeneic) on or after January 2012 - You are registered in the CIBMTR (an international transplant research database) **You may NOT be eligible if...** - You have not consented to your data being used for research Talk to your doctor to see if this trial is right for you.