Inv (11)(p15q21) in donor-derived Ph-negative cells in a patient with chronic myeloid leukemia in relapse successfully treated with imatinib mesylate post allogeneic stem cell transplantation.

Imatinib mesylate (IM) is the standard first-line treatment for patients with chronic myeloid leukemia (CML). Surprisingly, 2-15% of patients achieving a complete cytogenetic response develop cytogenetic abnormalities in Philadelphia (Ph)-negative cells. Following hematopoietic stem cell transplantation (HSCT), IM induces complete molecular responses (CMR) in approximately 70% patients with relapsed CML, and no IM-related cytogenetic abnormalities in Ph-negative donor-derived cells have been described after HSCT. We report a 56-year-old female who presented with a relapse from CML in September 2002. She had received a matched related HSCT for CML in chronic phase. Donor lymphocyte infusion was given 3 years post-HSCT for a relapse. Sustained CMR was achieved within 3 months of initiation of IM. In October 2005, routine evaluation demonstrated continuous CMR, full male donor engraftment and an inv (11) on donor cells. Evaluation of the donor demonstrated no dysplasia or cytogenetic abnormalities. This observation reinforces the possibility that IM therapy may be casually linked to the phenomenon of secondary cytogenetic changes in diploid cells.