Between July 2004 and January 2005, we started a process to standardize qualitative nested PCR and real-time quantitative PCR (RQ-PCR) assays using 1168 bone marrow (BM) samples which were leukemia-associated antigen-positive. Briefly, (1) Total RNA w ...
Between July 2004 and January 2005, we started a process to standardize qualitative nested PCR and real-time quantitative PCR (RQ-PCR) assays using 1168 bone marrow (BM) samples which were leukemia-associated antigen-positive. Briefly, (1) Total RNA was extracted and reverse transcription was performed. (2) We designed 1 set of primers for each type of transcript, reference ABL, and TaqMan probes. (3) After then, qualitative and quantitative PCR were performed with the standard conditions in triplicate. (4) We also undertook a study to clarify the significance of each transcript expression level and of its kinetics over the entire treatment course in patients having leukemia-associated antigen. The results were as follows: (1) Twenty-nine patients with Philadelphia chromosome-positive acute lymphoblastic leukemia who were treated with imatinib incorporation into conventional chemotherapy as an alternative and intended to undergo allogeneic stem cell transplantation (SCT) were enrolled in this study. To evaluate the BCR-ABL transcript expression and its kinetics, 272 BM samples were analyzed by qualitative and RQ-PCR. After the first imatinib cycle, the median BCR-ABL/ABL ratios decreased by 0.77 log in 25 (86.2%) responders, and their BCR-ABL/ABL ratios decreased further by 0.34 log after the second imatinib cycle, which included 7 molecular complete remission. One patient (4.3%) relapsed during the imatinib therapy. The remaining 3 patients were primarily refractory to both imatinib and chemotherapy. BCR-ABL transcript expression level and its kinetics were found to correlate well with the clinical courses of all patients (Blood. 2005;105:3449-3457, IF=9.782). (2) Seventy adults with PML-RARα-positive APL who achieved hematologic remission after an identical induction and intended to undergo consolidation and maintenance schedules were enrolled in this study. To evaluate the PML-RARα transcript expression and its kinetics, 762 BM samples were analyzed by qualitative and RQ-PCR. After induction, 34 (49.3%) of 69 evaluable patients achieved molecular remission. In the remaining 35 patients, the median PML-RARα/ABL ratio decreased by 3.14 log. After first consolidation, 23 of the 35 patients who were PCR-positive after induction became PCR-negative. In the remaining 12 patients, the median PML-RARα/ABL ratio decreased by 1.28 log. At a median follow-up of 44 months, PML-RARα/ABL ratio of greater than 10^-3 after first consolidation was the most powerful predictor of relapse (85.7% versus 7.3%, p<0.001) and DFS (14.3% versus 91.2%, p<0.001) (Haematologica/The Hematology Journal, in processing).
From February 2005 to June 2005, we undertook a study to standardize a protocol for minor histocompatibility antigen (mHag)-specific cytotoxic T lymphocytes (CTL) generation and ex vivo expansion. First, using dog leukocyte antigen (DLA)-identical transplant canine model, donor dendritic cells were cultured from BM-derived CD34+ cells and were used to stimulate recipient T lymphocytes on days 1, 10, and 20 of CTL culture at a 10:1 ratio, respectively. Before each restimulation, mHag-specific CTL activity was assessed using proliferation assay (3[H]TdR incorporation), 51Cr release assay, flow cytometry, ELISA, and ELISPOT. These results and experiences may allow us to develop an novel cellular immunotherapy using leukemia-associated antigen or mHag-targeted CTL for Korean population in the near future.