Clinical applicability and prognostic significance of molecular response assessed by fluorescent-PCR of immunoglobulin genes in multiple myeloma. Results from a GEM/PETHEMA study.

Minimal residual disease monitoring is becoming increasingly important in multiple myeloma (MM), but multiparameter flow cytometry (MFC) and allele-specific oligonucleotide polymerase chain reaction (ASO-PCR) techniques are not routinely available. This study investigated the prognostic influence of achieving molecular response assessed by fluorescent-PCR (F-PCR) in 130 newly diagnosed MM patients from Grupo Español Multidisciplinar de Melanoma (GEM)2000/GEM05 trials (NCT00560053, NCT00443235, NCT00464217) who achieved almost very good partial response after induction therapy. As a reference, we used the results observed with simultaneous MFC. F-PCR at diagnosis was performed on DNA using three different multiplex PCRs: IGH D-J, IGK V-J and KDE rearrangements. The applicability of F-PCR was 91·5%. After induction therapy, 64 patients achieved molecular response and 66 non-molecular response; median progression-free survival (PFS) was 61 versus 36 months, respectively (P = 0·001). Median overall survival (OS) was not reached (NR) in molecular response patients (5-year survival: 75%) versus 66 months in the non-molecular response group (P = 0·03). The corresponding PFS and OS values for patients with immunophenotypic versus non-immunophenotypic response were 67 versus 42 months (P = 0·005) and NR (5-year survival: 95%) versus 69 months (P = 0·004), respectively. F-PCR analysis is a rapid, affordable, and easily performable technique that, in some circumstances, may be a valid approach for minimal residual disease investigations in MM.

Evaluating gene expression profiling by quantitative polymerase chain reaction to develop a clinically feasible test for outcome prediction in multiple myeloma.

The gene expression profiles (GEPs) of 96 selected genes were analysed by real-time quantitative polymerase chain reaction (qPCR) with a TaqMan low-density array card in isolated tumour plasma cells (PCs) from 157 newly diagnosed multiple myeloma (MM) patients. This qPCR-based GEP correctly classified cases following the Translocation-cyclin D classification. Classic prognostic parameters and qPCR-based GEP predicted MM patient outcome and, although multivariate analyses revealed that cytogenetic risk (standard vs. high risk) was the variable that most strongly predicted prognosis, GEP added significant information for risk stratification. Considering only the standard risk cytogenetic patients, multivariate analyses revealed that high ß2-microglobulin, low CDKN1A and high SLC19A1 gene expression levels independently predicted a short time-to-progression (TTP), while high International Staging System stage, low CDKN2B and high TBRG4 gene expression predicted poor overall survival (OS). A gene expression risk score enabled the division of standard risk patients into two groups with different TTPs (83% vs. 38% at 3 years, P < 0·0001) and OS rates (88% vs. 61% at 5 years; P = 0·003). This study demonstrates that quantitative PCR is a robust, accurate and feasible technique for implementing in the daily routine as a surrogate for GEP-arrays.

Comparison of immunofixation, serum free light chain, and immunophenotyping for response evaluation and prognostication in multiple myeloma.

PURPOSE: To investigate the impact of immunophenotypic response (IR) versus complete response (CR) and CR plus normal serum free light chain (sFLC) ratio (stringent CR) in elderly patients with multiple myeloma (MM) treated with novel agents. PATIENTS AND METHODS: From a total of 260 elderly patients newly diagnosed with MM included in the GEM05>65y trial, 102 patients achieving at least a partial response with ≥ 70% reduction in M-component after the six planned induction cycles were simultaneously analyzed by immunofixation, sFLC, and multiparameter flow cytometry (MFC) immunophenotyping; this population is the focus of this study. RESULTS: Forty-three percent of patients achieved CR, 30% achieved stringent CR, and 30% achieved IR. Patients in stringent CR showed no significant survival advantage compared with those in CR, whereas patients in IR showed significantly increased progression-free survival (PFS) and time to progression (TTP) compared with those in stringent CR or CR; this was confirmed by multivariate analysis (hazard ratio, 4.1; P = .01 for PFS). Discrepancies between the three techniques were relatively common. Notably, in all seven patients achieving IR but remaining immunofixation positive, the M-component disappeared in follow-up analysis. In contrast, MFC-positive patients who were immunofixation negative (n = 20) showed a tendency toward early reappearance of the M-component (median, 3 months). Similarly, in five of 11 stringent CR but MFC-positive patients, symptomatic disease progression was recorded at a median of 13 months after induction. CONCLUSION: Achieving an IR translates into superior PFS and TTP compared with conventional CR or stringent CR. These techniques provide complementary information and thus, an effort should be made to refine response criteria in MM.

Evaluation of minimal residual disease in multiple myeloma patients by fluorescent-polymerase chain reaction: the prognostic impact of achieving molecular response.

This study aimed to standardize a simple molecular method for evaluating the response to treatment in multiple myeloma (MM) patients after high dose chemotherapy. Fifty three patients enrolled in the GEM2000 protocol were studied for minimal residual disease (MRD) using both fluorescent-polymerase chain reaction (F-PCR) and flow cytometry. Most patients had achieved complete remission or very good response after autologous stem cell transplantation. The molecular analysis of immunoglobulin gene rearrangements at diagnosis and during the follow-up was carried out by F-PCR according to the Biomed-2 protocols. F-PCR could be used in 91% of the patients and the results were similar to flow cytometry. F-PCR was able to identify a group of patients with a better prognosis [progression-free survival (PFS) 67.86% in patients with negative F-PCR vs. 28%; P = 0.001], even amongst patients who achieved a complete response with negative immunofixation (PFS 75% vs. 25%; P = 0.002). Multivariate analysis identified the F-PCR result as the only variable to show a prognostic value when PFS was analysed. F-PCR of DHJ and light chain rearrangements of immunoglobulin genes is a feasible method for evaluating MRD in MM patients after intensive therapy. Achieving molecular response by F-PCR shows prognostic value.