title: Peripheral blood stem cell contamination evaluated by a highly sensitive molecular method fails to predict outcome of autotransplanted multiple myeloma patients.
abstract: To evaluate the clinical impact of minimal residual disease in multiple myeloma, apheretic products from 51 autotransplanted patients were tested by fluorescent (GeneScan) polymerase chain reaction (PCR). Sixty-nine per cent of harvests were contaminated when evaluated for IgH rearrangement. Forty-six patients responded to transplant, with 52.9% achieving complete response (CR). The clinical response of patients was significantly influenced by the number of re-infused CD34+ cells. Positive PCR results of re-infused harvests were not significantly related to patient outcome. Median overall survival (OS) was 33 months, and a significant advantage for patients transplanted by 12 months from diagnosis was observed. Moreover, OS was longer for patients receiving PCR-negative stem cells, with 72% of patients surviving to 70 months in the group receiving PCR-negative harvests vs 48% in the group transplanted with contaminated precursors (not statistically significant). Ex vivo purging caused a reduction of contamination of up to 3 logs; nevertheless, 80% of purged harvests remained PCR-positive and the purging procedure did not alter response or survival rates. Thus, the failure of a predictive role for this highly sensitive molecular method could be explained by the assumption that in vivo persisting malignant cells are the true source of relapse in MM.
authors.affiliation: Department of Oncology, Transplant and Advances in Medicine, Section of Haematology, University of Pisa, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Galimberti
authors.forename: Fortunato
authors.initials: F
authors.lastname: Morabito
authors.forename: Francesca
authors.initials: F
authors.lastname: Guerrini
authors.forename: Giuseppe Alberto
authors.initials: GA
authors.lastname: Palumbo
authors.forename: Antonio
authors.initials: A
authors.lastname: Azzará
authors.forename: Massimo
authors.initials: M
authors.lastname: Martino
authors.forename: Edoardo
authors.initials: E
authors.lastname: Benedetti
authors.forename: Francesco
authors.initials: F
authors.lastname: Di Raimondo
authors.forename: Mario
authors.initials: M
authors.lastname: Petrini
mesh_terms: D000328:Adult; D000368:Aged; D016465:Bone Marrow Purging / Q000379:methods; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D015321:Gene Rearrangement; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000473:pathology; D006801:Humans; D007937:Leukapheresis; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000175:diagnosis / Q000628:therapy*; D018365:Neoplasm, Residual; D016133:Polymerase Chain Reaction / Q000379:methods; D012189:Retrospective Studies; D015996:Survival Rate; D016896:Treatment Outcome