Date Published: February 22, 2019
Publisher: Public Library of Science
Author(s): Jennifer Valero-Garcia, María del Carmen González-Espinosa, Manuel Barrios, Greta Carmona-Antoñanzas, Javier García-Planells, Carlos Ruiz-Lafora, Ainhoa Fuentes-Gálvez, Antonio Jiménez-Velasco, Francesco Bertolini.
The analysis of molecular haematopoietic chimerisms (HC) has become a well-established method to monitor the transplant evolution and to assess the risk of relapse after allogeneic stem cells transplantation (allo-STC). Different techniques and molecular markers are being used for chimerism surveillance after transplantation, including quantitative real-time PCR (qPCR) and the recently developed digital PCR (dPCR). This study aims to compare the sensitivity and accuracy of both methods to quantify HC and predict early relapse.
HC was evaluated using custom PCR systems for the specific detection of the Y-chromosome, null alleles and insertion-deletion polymorphisms. A total of 281 samples from 28 adult patients who underwent an allo-SCT were studied. Increasing mixed chimerism was detected prior to relapse in 100% of patients (18 relapses).
Compared with conventional qPCR amplification, dPCR predicted relapse with a median anticipation period of 63 days versus 45.5 days by qPCR. Overall, 56% of the relapses were predicted earlier with dPCR whereas 38% of the relapses where detected simultaneously using both techniques and only in 1 case, relapse was predicted earlier with qPCR.
In conclusion, chimerism determination by dPCR constitutes a suitable technique for the follow-up of patients with haematological pathologies after allo-STC, showing greater sensitivity to predict an early relapse.
Allogeneic Stem Cell Transplantation (allo-SCT) is considered to be the strongest immunotherapy for a variety of malignant and non-malignant hematologic disorders. Despite its strong curative potential and improved safety, allo-SCT remains a high-risk procedure . Haematopoietic chimerism (HC) analysis, distinguishing recipient from donor cell subsets after allo-SCT, has become an important and well-established method to monitor the graft health, predict early detection of disease relapse and provide useful information on the graft-versus-host disease (GvHD) or graft-versus-tumor (GvT) effect, facilitating therapeutic intervention .
Despite the continuous improvements in allo-SCT, relapse remains one of the main causes of failure of the procedure, especially in patients with acute leukaemia. HC analysis constitutes a standard procedure in the follow-up of patients undergoing allo-SCT capable to predict disease recurrence, graft-versus-host disease and graft failure. In a significant proportion of patients there is no minimal residual disease marker that allows us to monitor the risk of relapse, whereas the analysis of chimerism is possible in almost every patient. STR-PCR analysis is the gold standard for quantitative chimerism analysis recommended by the EuroChimerism consortium in the prediction of relapses [12,23]; however, its limited sensitivity, allelic imbalance and high coefficient of variation at low percentage of mixed chimerism has opened the ground to investigate novel technologies [12,20,24].