Incidence of phenotypic aberrations in a series of 467 patients with B chronic lymphoproliferative disorders: basis for the design of specific four-color stainings to be used for minimal residual disease investigation.

Multiparameter immunophenotypic analysis of neoplastic cells has proven to be of great help for the investigation of minimal residual disease in acute leukemias; however, its utility has not been systematically explored in B cell chronic lymphoproliferative disorders. The aim of the present study was to investigate the incidence of phenotypic aberrations in a series of 467 consecutive leukemic B cell chronic lymphoproliferative disorders through the comparison of the phenotypic characteristics of tumor vs normal peripheral blood (n = 10) and bone marrow (n = 10) B cells, in order to explore the applicability of this strategy for minimal residual disease monitoring. An additional goal of our study was to evaluate the sensitivity of multiparameter flow cytometry for the detection of minimal residual disease in leukemic B cell chronic lymphoproliferative disorders through dilutional experiments (n = 19). From the patients analyzed 382 corresponded to B cell chronic lymphocytic leukemia/small lymphocytic lymphoma (353 typical and 29 atypical); five to prolymphocytic leukemia; 13 to hairy cell leukemias; 12 to lymphoplasmacytic lymphomas; 14 to splenic marginal zone lymphomas; 22 were follicular lymphomas; and 19 mantle cell lymphomas. The following triple stainings were systematically applied to both normal and leukemic samples: FMC7/CD5/CD19, CD22/CD23/CD19, CD103/CD25/CD19, CD10/CD11c/CD19 and sIg/sIg(lambda)/CD19. Overall, 98% of the leukemic B cell chronic lymphoproliferative disorders cases displayed aberrant phenotypes at diagnosis with no significant differences being found between cases analyzed in peripheral blood vs bone marrow samples. The most common types of aberrant criteria detected included asynchronous antigen expression (92%) and antigen over-expression (54%); abnormally light scatter characteristics were found in 17% of the cases. Most of the cases studied (90%) displayed four or more phenotypic aberrations. Once patients were divided according to the different diagnostic subgroups, the overall incidence of aberrant phenotypes ranged from 79 to 80% among atypical B cell chronic lymphocytic leukemia/small lymphocytic lymphoma and prolymphocytic leukemia to 97% of follicular lymphoma and 100% of typical B cell chronic lymphocytic leukemia/small lymphocytic lymphoma, hairy cell leukemia, lymphoplasmacytic lymphomas, splenic marginal zone lymphomas and mantle cell lymphomas. Based on the aberrant phenotypes detected unique four-color stainings could be built for the specific identification of aberrant phenotypes. These include CD22/CD23/CD19/CD5 and sIg(kappa)/sIg(lambda)/CD19/CD5 for lymphocytic leukemia/small lymphocytic lymphoma and prolymphocytic leukemia, CD103/CD25 or CD22/CD19/CD11c for hairy cell leukemia, FMC7/CD22/CD19/CD103 and sIg(kappa)/sIg(lambda)/CD22/CD19 for splenic marginal zone lymphomas, CD22/CD23/CD19/CD10 for follicular lymphomas and CD10/CD22/CD19/CD5 for mantle cell lymphomas. Serial dilutional experiments showed that the sensitivity level of immunophenotyping ranges between 10(-4) and 10(-5). In summary, the present study shows that immunophenotypic analysis allows the identification of aberrant phenotypes in 98% of leukemic B cell chronic lymphoproliferative disorders and these phenotypes can be used for minimal residual disease monitoring with a sensitivity limit of 10(-4)-10(-5).

Early immunophenotypical evaluation of minimal residual disease in acute myeloid leukemia identifies different patient risk groups and may contribute to postinduction treatment stratification.

Early response to therapy is one of the most important prognostic factors in acute leukemia. It is hypothesized that early immunophenotypical evaluation may help identify patients at high risk for relapse from those who may remain in complete remission (CR). Using multiparametric flow cytometry, the level of minimal residual disease (MRD) was evaluated in the first bone marrow (BM) in morphologic CR obtained after induction treatment from 126 patients with acute myeloid leukemia (AML) who displayed aberrant phenotypes at diagnosis. Based on MRD level, 4 different risk categories were identified: 8 patients were at very low risk (fewer than 10(-4) cells), and none have relapsed thus far; 37 were at low risk (10(-4) to 10(-3) cells); and 64 were at intermediate risk (fewer than 10(-3) to 10(-2) cells), with 3-year cumulative relapse rates of 14% and 50%, respectively. The remaining 17 patients were in the high-risk group (more than 10(-2) residual aberrant cells) and had a 3-year relapse rate of 84% (P =.0001). MRD level not only influences relapse-free survival but also overall survival (P =.003). The adverse prognostic impact was also observed when M3 and non-M3 patients with AML were separately analyzed, and was associated with adverse cytogenetic subtypes, 2 or more cycles to achieve CR, and high white blood cell counts. Multivariate analysis showed that MRD level was the most powerful independent prognostic factor, followed by cytogenetics and number of cycles to achieve CR. In conclusion, immunophenotypical investigation of MRD in the first BM in mCR obtained after AML induction therapy provides important information for risk assessment in patients with AML.

Molecular characterization of acute myeloblastic leukemia according to the new WHO classification: a different distribution in Central-West Spain.

BACKGROUND AND OBJECTIVES: Molecular analysis has contributed to the identification of several non-random chromosomal translocations, such as t(15;17), t(8:21), inv(16)/t(16;16) and 11q23 abnormalities, typically associated with acute myeloid leukemia (AML). The identification of these chromosomal abnormalities helps not only to define different AML subtypes with distinct prognoses and treatments but also to monitor the disappearance of malignant cells after treatment. Recent reports suggest that the frequency of these alterations may differ according to geographic distribution. However, most of these reports focus on just one or two genetic alterations, which may lead to some selection bias. Appropriate epidemiological studies should be based on unselected consecutive series of patients in which all relevant genes are simultaneously analyzed. The aim of the present study was to explore whether or not the incidence of genetic lesions in Spanish AML patients differs from that reported in other countries. DESIGN AND METHODS: In a series of 145 consecutive un-selected adult patients with AML we simultaneously analyzed the presence of 4 genetic abnormalities, PML/RARalpha for t(15;17), AML1/ETO for t(8;21), CBFbeta/MYH11 for inv(16)/t(16;16) and rearrangements of the MLL gene for 11q23 abnormalities. AML were classified using the new World Health Organization (WHO) classification for hematologic malignancies. The techniques used were standardized according to the recommendations of the European BIOMED-1 Concerted Action. RESULTS: The PML/RARalpha transcript was present in 34 patients (23.4%) (23 were bcr1, 2 bcr2 and 9 bcr3). The AML1/ETO fusion transcript was detected in only 2 cases (1.4%) both with M2 morphology, but 29 other cases with M2 morphology were negative. CBFbeta/MYH11 transcript was present in 9 cases (6.2%) eight of them displaying M4Eo morphology. Finally, 5 cases (3.5%) showed rearrangements of theMLL gene. Our results differ from those reported from the United States and North/Central Europe, particularly regarding the incidence of t(15;17) and t(8;21) translocations. In Spain the frequency of t(15;17) is higher while that of t(8;21) is lower. INTERPRETATION AND CONCLUSIONS: These data add epidemiological information about geographic heterogeneity of such chromosome aberrations in AML and would contribute to the design of specific screening strategies adapted to the incidence in each country.

An abnormal CD34+ myeloid/CD34+ lymphoid ratio at the end of chemotherapy predicts relapse in patients with acute myeloid leukemia.

During conventional follow-up of patients with acute myeloid leukemia (AML), the emergence of cytopenias is considered to be a sign of impending relapse, and it represents an example of how leukemic hematopoiesis affects normal hemopoietic differentiation. In the present study, we have explored the possible value of the analysis of the distribution of CD34+ myeloid and CD34+ lymphoid progenitor cells in follow-up complete remission bone marrow samples from de novo AML patients as a prognostic parameter for predicting relapse. A total of 213 bone marrow samples from 36 AML patients in morphological complete remission, obtained at the end of induction, consolidation, and intensification therapy and every six months thereafter were analyzed. The normal CD34+ myeloid/CD34+ lymphoid ratio ranged between 2.4 and 8.9. In contrast, in most AML cases an abnormally high ratio (> or =10) was observed at the end of induction and consolidation therapy: 96% and 75% of cases, respectively. On the other hand, at the end of intensification, 70% of the patients displayed a normal CD34+ ratio. Patients with a myeloid/lymphoid CD34+ ratio higher than 10 at the end of intensification showed a significantly lower overall survival (median survival of 19 months versus median not reached, P = 0.05), as well as a lower disease-free survival (median of 7 months versus 30 months, P = 0.0001). Regarding sequential studies, 67% of the relapses were preceded by the re-appearance of an abnormal CD34 ratio, whereas relapse was not predicted in four patient with leukemia classified as M3 undergoing maintenance therapy. From the remaining 18 patients who are still in continuous complete remission, all except 3 cases (17%) displayed a normal CD34 myeloid/lymphoid ratio. In summary, the present study shows that the persistence at the end of chemotherapy of an abnormally high (> or =10) ratio between CD34+ myeloid and CD34+ lymphoid progenitors in the bone marrow of AML patients is associated with high risk of relapse and a shorter overall survival.

Immunophenotyping investigation of minimal residual disease is a useful approach for predicting relapse in acute myeloid leukemia patients.

A high complete remission rate is currently achieved in patients with acute myeloid leukemia (AML). However, many patients eventually relapse due to the persistence of low numbers of residual leukemic cells that are undetectable by conventional cytomorphologic criteria (minimal residual disease [MRD]). Using immunophenotypic multiparametric flow cytometry, we have investigated in sequential studies (diagnosis and follow-up) the impact of MRD detection on the outcome of 53 AML patients that had achieved morphologic remission with standard AML protocols and displayed at diagnosis an aberrant phenotype. Patients were studied at diagnosis with a panel of 35 monoclonal antibodies in triple staining combinations for detection of aberrant or uncommon phenotypic features. According to these features, a patient's probe was custom-built at diagnosis for the identification of possible residual leukemic cells during follow-up. The level of MRD at the end of induction and intensification therapy correlated with the number of relapses and relapse-free survival (RFS). Thus, patients with more than 5 x 10(-3) residual cells (5 residual cells among 1,000 normal bone marrow [BM] cells) identified as leukemic by immunophenotyping in the first remission BM showed a significant higher rate of relapse (67% v 20% for patients with less than 5 x 10(-3) residual cells; P = .002) and a lower median RFS (17 months v not reached; P = .01). At the end of intensification, with a cut-off value of 2 x 10(-3) leukemic cells, AML patients also separated into two distinct groups with relapse rates of 69% versus 32% (P = .02), respectively, and median RFS of 16 months versus not reached (P = .04). In addition, overall survival was also significantly related to the level of residual cells in the marrow obtained at the end of induction and particularly after intensification therapy (P = .008). Furthermore, we have explored whether residual disease was related with the functional expression of multidrug resistance (MDR-1) at diagnosis as assessed by the rhodamine123 assay. Patients with > or =5 x 10(-3) residual leukemic cells at the end of induction therapy had a significantly higher rhodamine-123 efflux (mean, 56% +/- 24%) than those with less than 5 x 10(-3) residual cells (mean, 32% +/- 31%; P = .04). Finally, multivariate analysis showed that the number of residual cells at the end of induction or intensification therapy was the most important prognostic factor for prediction of RFS. Overall, our results show that immunophenotypical investigation of MRD strongly predicts outcome in patients with AML and that the number of residual leukemic cells correlates with multidrug resistance.

Bone marrow histopathologic patterns and immunologic phenotype in B-cell chronic lymphocytic leukaemia.

The present work analyzes the clinicobiological and immunological characteristics - the latter hitherto unexplored - of the different bone marrow histopathological patterns of the B-cell chronic lymphocytic leukaemia (B-CLL). In addition, we studied whether any or some of these parameters were able to predict the probability of a particular pattern of bone marrow involvement appearing. Of the 100 B-CLL cases studied 41 had a diffuse pattern and 59 were non-diffuse - interstitial 27, nodular 11 and mixed 21 -. Neither clinical nor immunological differences were observed among the distinct non-diffuse patterns. The patients in the diffuse group displayed an increased incidence of mu+ isotype and a higher proportion of HLA-DR and HAN-PC 1 positive cells while, conversely, reactivity with the FMC 8 McAb was lower. In addition, patients with a diffuse pattern of BM involvement displayed features of a more extensive disease: a higher incidence of adenopathies (p less than 0.05), hepatomegaly (p less than 0.01), splenomegaly (p less than 0.01), anaemia (p less than 0.01) and thrombopenia (p less than 0.01) as well as higher levels of peripheral blood lymphocytosis (p less than 0.05) and a higher percentage of BM lymphocytic infiltration (p less than 0.001). Multiple regression analysis showed that thrombopenia and splenomegaly were the two most important features in predicting the probability of a diffuse pattern.