González M

Design and standardization of PCR primers and protocols for detection of clonal immunoglobulin and T-cell receptor gene recombinations in suspect lymphoproliferations: report of the BIOMED-2 Concerted Action BMH4-CT98-3936.

In a European BIOMED-2 collaborative study, multiplex PCR assays have successfully been developed and standardized for the detection of clonally rearranged immunoglobulin (Ig) and T-cell receptor (TCR) genes and the chromosome aberrations t(11;14) and t(14;18). This has resulted in 107 different primers in only 18 multiplex PCR tubes: three VH–JH, two DH–JH, two Ig kappa (IGK), one Ig lambda (IGL), three TCR beta (TCRB), two TCR gamma (TCRG), one TCR delta (TCRD), three BCL1-Ig heavy chain (IGH), and one BCL2-IGH. The PCR products of Ig/TCR genes can be analyzed for clonality assessment by heteroduplex analysis or GeneScanning. The detection rate of clonal rearrangements using the BIOMED-2 primer sets is unprecedentedly high. This is mainly based on the complementarity of the various BIOMED-2 tubes. In particular, combined application of IGH (VH–JH and DH–JH) and IGK tubes can detect virtually all clonal B-cell proliferations, even in B-cell malignancies with high levels of somatic mutations. The contribution of IGL gene rearrangements seems limited. Combined usage of the TCRB and TCRG tubes detects virtually all clonal T-cell populations, whereas the TCRD tube has added value in case of TCRγδ+ T-cell proliferations. The BIOMED-2 multiplex tubes can now be used for diagnostic clonality studies as well as for the identification of PCR targets suitable for the detection of minimal residual disease.

BEAM chemotherapy followed by autologous stem cell support in lymphoma patients: analysis of efficacy, toxicity and prognostic factors

In the present paper, we evaluate tolerability, outcome and prognostic factors in patients with poor prognosis non-Hodgkin’s lymphoma (NHL) and Hodgkin’s disease (HD) when uniformly treated with BCNU, etoposide, cytarabine and melphalan (BEAM) and autologous stem cell transplant (ASCT). One hundred and forty-eight patients with NHL (n = 112) or HD (n = 36) received BEAM followed by infusion of bone marrow (n = 55), peripheral blood stem cells (n = 79) or both (n = 14). Twenty-eight patients had low-grade lymphoma (LGL), 68 intermediate- and 16 high-grade lymphoma (IGL). Within the NHL group, 21 patients were in 2nd or subsequent complete remission (CR) at transplant, 34 had sensitive disease and 11 resistant disease; 46 patients were transplanted in 1st CR due to the presence of ⩾2 adverse prognostic features at diagnosis or to a slow CR. Of the HD patients at transplant 17 had active disease, 16 were in ⩾2 CR and three in 1st CR. The overall percentage of toxic deaths was 5.4%, while in the group of patients transplanted with PBSC it was only 1.3%. NHL patients: 78% were in CR following ASCT, including 25 out of 45 patients (56%) who were transplanted with active disease. Only two of the 11 patients transplanted with resistant disease achieved CR. Incidence of overall survival (OS) and disease-free survival (DFS) at 3 years was 65 and 75%, respectively. As far as histology was concerned, OS was significantly better for patients with LGL in comparison with IGL (88 vs 56%) (P = 0.002). DFS was significantly higher for patients transplanted in first CR or first partial remission (PR) than it was for those transplanted in a later CR or PR (86 vs 53%) (P = 0.02). Multivariate analysis for OS showed that histology, bulky disease, poor performance status at transplant and achievement of CR were independent prognostic factors. In addition, a high number of infused MNC was associated with poor DFS. HD patients: 30 (83%) were in CR after transplantation, with 25 maintaining CR at the end of the study. Only one of the four patients transplanted with resistant disease reached CR. Incidence of OS and DFS at 3 years was 78 and 81%. DFS was similar for patients transplanted with early or late relapse (95 and 93%). With multivariate analysis, the only independent variable for OS was CR after transplant. In conclusion, the present results demonstrate the efficacy and low toxicity of the BEAM regimen in high-risk lymphoma patients with sensitive disease. Other strategies should be investigated for patients with refractory lymphoma.

Chimerism and minimal residual disease monitoring after reduced intensity conditioning (RIC) allogeneic transplantation

Since graft-versus-leukemia (GVL) is the main weapon for disease eradication after reduced intensity conditioning (RIC) allogeneic SCT, the availability of sensitive and specific techniques to monitor changes in tumor load after transplant are especially helpful. These minimal residual disease techniques would allow an early intervention in the event of low tumor burden, for which immunotherapy is highly effective. Some authors have found an association between persistence of MRD, mixed chimerism and risk of relapse. Nevertheless, data from the literature remain contradictory and further correlations should be established, especially in RIC transplants. In this study we have analyzed the impact of MRD and chimerism monitoring on the outcome of 34 patients undergoing RIC allogeneic SCT who were considered poor candidates for conventional transplantation due to advanced age or other concurrent medical conditions. At day +100 25 (75%) patients reached complete remission (CR), there were five (15%) partial responses and three patients progressed. Incidence of grade 2–4 aGVHD and extensive cGVHD were 35% and 58%, respectively. Sixteen percent of patients developing aGVHD relapsed as compared to 47% in those without aGVHD (P = 0.03) and also 10% of patients developing cGVHD relapsed as compared to 50% relapses in those without cGHVD (P = 0.03). Four patients (12%) died due to early (n = 1) and late (n = 3) transplant-related mortality. After a median follow-up of 15 months, 24 out of the 34 patients remain alive. Projected overall survival and disease-free survival at 3 years are 68% and 63%, respectively. Early chimerism analysis showed 67% of patients with complete chimerism (CC) in bone marrow (BM), 86% in peripheral blood (PB), 89% in granulocytes and 68% in T lymphocytes. On day +100, these figures were 68%, 79%, 90% and 73%, respectively, and on day +180 there were 83% patients with CC in BM, 100% in PB, 100% in granulocytes and 100% in T lymphocytes. We observed a trend to a higher incidence of relapse in patients with mixed chimerism (MC) as compared to patients with CC. MRD monitoring by flow cytometry and/or RT-PCR analysis was performed in 23 patients. MRD assessment on days +21 to +56 after transplant allowed identification of patients at risk of relapse. In this sense, seven out of 12 patients (58.3%) who had positive MRD on days +21 to +56 relapsed as compared to none out of 11 patients who had negative MRD (P = 0.002). Of the seven patients with criteria to monitor MRD who relapsed after transplant, all but one remained MRD positive until relapse. By contrast, 10 patients remained MRD negative and all of them are in continuous CR. In nine additional patients, persistence of MRD or mixed chimerism was observed after transplant and withdrawal of cyclosporin with or without DLI was performed. Only two out of these nine patients relapsed. MRD clearance was preceded by CC and GVHD. In conclusion, in our study we found that RIC allogeneic transplantation can be used in patients considered poor candidates for conventional transplantation due to advanced age or other concurrent medical conditions with both low toxicity and low transplant-related mortality. Simultaneous studies of both chimerism and MRD are a useful tool in order to predict risk of relapse in patients undergoing RIC transplants and so can be helpful for individualizing treatment strategies after transplant.

Adult precursor B-ALL with BCR/ABL gene rearrangements displays a unique immunophenotype based on the pattern of CD10, CD34, CD13 and CD38 expression

The Philadelphia chromosome (Ph+) reflects a balanced reciprocal translocation between the long arms of chromosomes 9 and 22 [t(9;22)(q34;q11.2] involving the BCRand ABL genes. At present, detection of BCR/ABL gene rearrangements is mandatory in precursor-B-ALL patients at diagnosis for prognostic stratification and treatment decision. In spite of the clinical impact, no screening method, displaying a high sensitive and specificity, is available for the identification of BCR/ABL+precursor-B-ALL cases. The aim of the present study was to explore the immunophenotypic characteristics of precursor B-ALL cases displaying BCR/ABL gene rearrangements using multiple stainings analyzed by quantitative flow cytometry in order to rapidly (<1 h) identify unique phenotypes associated with this translocation. From the 82 precursor-B-ALL cases included in the study 12 displayed BCR/ABL gene rearragements, all corresponding to adult patients, four of which also displayed DNA aneuploidy. Our results show that BCR/ABL+ precursor B-ALL cases constantly displayed a homogeneous expression of CD10 and CD34 but low and relatively heterogeneous CD38 expression, together with an aberrant reactivity for CD13. In contrast, this unique phenotype was only detected in three out of 70 BCR/ABL− cases. Therefore, the combined use of staining patterns for CD34, CD38 and CD13 expression within CD10-positive blast cells is highly suggestive of BCR/ABL gene rearrangements in adults with precursor B-ALL.

Critical evaluation of ASO RQ-PCR for minimal residual disease evaluation in multiple myeloma. A comparative analysis with flow cytometry

We have analyzed the applicability, sensitivity and prognostic value of allele-specific oligonucleotide real-time quantitative PCR (ASO RQ-PCR) as a method for minimal residual disease (MRD) assessment in patients with multiple myeloma (MM), comparing the results with those of multiparameter flow cytometry (MFC). A total of 170 patients enrolled in three consecutive Spanish trials achieving at least partial response after treatment were included. Lack of clonality detection (n=31), unsuccessful sequencing (n=17) and suboptimal ASO performance (n=51) limited the applicability of PCR to 42% of cases. MRD was finally investigated in 103 patients (including 32 previously studied) with persistent disease identified by PCR and MFC in 54% and 46% of cases, respectively. A significant correlation in MRD quantitation by both the techniques was noted (r=0.881, P<0.001), being reflective of treatment intensity. Patients with <10−4 residual tumor cells showed longer progression-free survival (PFS) compared with the rest (not reached (NR) vs 31 months, P=0.002), with similar results observed with MFC. Among complete responders (n=62), PCR discriminated two risk groups with different PFS (49 vs 26 months, P=0.001) and overall survival (NR vs 60 months, P=0.008). Thus, although less applicable than MFC, ASO RQ-PCR is a powerful technique to assess treatment efficacy and risk stratification in MM.

Minimal number of circulating CD34+ cells to ensure successful leukapheresis and engraftment in autologous peripheral blood progenitor cell transplantation

BACKGROUND: The number of peripheral blood (PB) CD34+ cells has been widely used to monitor the timing of leukapheresis for autologous transplantation. However, no cutoff value for CD34+ cells in PB has been defined as a guideline for the identification of patients in whom the harvest would be effective and those in whom there was a high probability of failure.

Gene expression profile reveals deregulation of genes with relevant functions in the different subclasses of acute myeloid leukemia.

Bone marrow samples from 43 adult patients with de novo diagnosed acute myeloid leukemia (AML) – 10 acute promyelocytic leukemias (APL) with t(15;17), four AML with inv(16), seven monocytic leukemias and 22 nonmonocytic leukemias – were analyzed using high-density oligonucleotide microarrays. Hierarchical clustering analysis segregated APL, AML with inv(16), monocytic leukemias and the remaining AML into separate groups. A set of only 21 genes was able to assign AML to one of these three classes: APL, inv(16) and other AML subtype without a specific translocation. Quantitative RT-PCR performed for 18 out of these predictor genes confirmed microarray results. APL expressed high levels of FGF13 and FGFR1 as well as two potent angiogenic factors, HGF and VEGF. AML with inv(16) showed an upregulation of MYH11 and a downregulation of a gene encoding a core-binding factor protein, RUNX3. Genes involved in cell adhesion represented the most altered functional category in monocytic leukemias. Two major groups emerged from the remaining 22 AML: cluster A with 10 samples and cluster B with 12. All the eight leukemias that were either refractory to treatment or that relapsed afterwards were assigned to cluster B. In the latter cluster, CD34 upregulation and serine proteases downregulation is consistent with a maturation arrest and lack of granulocytic differentiation.

Chimerism analysis following allogeneic peripheral blood stem cell transplantation with reduced-intensity conditioning.

Summary:We have performed a prospective study to evaluate early chimerism and its kinetics after allogeneic peripheral blood stem cell transplantation among 68 patients who received a reduced-intensity conditioning (RIC) regimen with fludarabine plus melphalan (n=40) or busulphan (n=28). Chimerism was analyzed by polymerase chain reaction amplification of short tandem repeats in unfractionated (UF) and/or fractionated nucleated cells from bone marrow and peripheral blood (PB). All of the patients showed initial donor engraftment and no patient presented primary or secondary graft failure. In UF samples, the probability of achieving stable complete donor chimerism (CDC) in PB within the first 6 months was 70% on day +30, 85% on day +100 and 95% on day +180. CDC in granulocytes was observed in nearly all cases from day +30 onwards. CDC in T cells, however, differed among melphalan and busulphan recipients during the first 3 months (100 vs 0% on day +30 and 93 vs 20% on day +90, respectively). In multivariate analysis, the only significant variable associated with the achievement of early CDC was having received more than two lines of chemotherapy pretransplant (P<0.02). No correlation was found between the rate of achieving early CDC and the occurrence of acute graft-versus-host disease (GVHD) or disease progression post-transplant. In multivariate analysis, the only variable that influenced the incidence of disease progression post-transplant was the development of chronic extensive GVHD (P<0.05). In conclusion, a state of CDC is readily obtained within the first 6 months after our RIC protocols. Donor myeloid engraftment occurs rapidly in all cases, while early T-cell CDC is more common in more immunosuppressed hosts and, perhaps, in melphalan recipients.

SNP-based mapping arrays reveal high genomic complexity in monoclonal gammopathies, from MGUS to myeloma status

Genetic events mediating transformation from premalignant monoclonal gammopathies (MG) to multiple myeloma (MM) are unknown. To obtain a comprehensive genomic profile of MG from the early to late stages, we performed high-resolution analysis of purified plasma cells from 20 MGUS, 20 smoldering MM (SMM) and 34 MM by high-density 6.0 SNP array. A progressive increase in the incidence of copy number abnormalities (CNA) from MGUS to SMM and to MM (median 5, 7.5 and 12 per case, respectively) was observed (P=0.006). Gains on 1q, 3p, 6p, 9p, 11q, 19p, 19q and 21q along with 1p, 16q and 22q deletions were significantly less frequent in MGUS than in MM. Although 11q and 21q gains together with 16q and 22q deletions were apparently exclusive of MM status, we observed that these abnormalities were also present in minor subclones in MGUS. Overall, a total of 65 copy number-neutral LOH (CNN-LOH) were detected. Their frequency was higher in active MM than in the asymptomatic entities (P=0.047). A strong association between genetic lesions and fragile sites was also detected. In summary, our study shows an increasing genomic complexity from MGUS to MM and identifies new chromosomal regions involved in CNA and CNN-LOH.

Detection of abnormalities in B-cell differentiation pattern is a useful tool to predict relapse in precursor-B-ALL

Immunophenotypic investigation of minimal residual disease (MRD) has traditionally been based on the investigation of phenotypic aberrants at diagnosis to be used later as a target for MRD detection. This approach has several shortcomings (it is only applicable to patients with aberrant phenotypes, requires a diagnostic sample, and is patient‐specific) and therefore a search for simpler alternatives is warranted. The present study is based on the hypothesis that in precursor‐B‐ALL patients the persistence of residual leukaemic cells may induce abnormalities in the precursor‐B‐cell compartment in bone marrow (BM) and these could be used as a criteria to predict relapse.  These abnormalities may include: (1) the presence of an increase in the frequencies of immature B cells (CD34+/CD19+ or CD20−/CD19+) or (2) the existence of an altered B‐cell differentiation pathway due to a blockade or to the presence of B cells outside the normal pathway. A total of 180 BM samples from 45 consecutive precursor‐B‐ALL patients who achieved morphological complete remission (CR) were analysed by multiparametric flow cytometry. Our results show that a significant increase in immature B‐cell subsets or an altered B‐cell differentiation predicts a high relapse rate (P < 0.01) and a shorter disease‐free survival (P < 0.01). Moreover, abnormalities in either of these two criteria detected at specific time points during follow‐up (end of induction, maintenance, or after treatment) were associated with a significantly shorter disease‐free survival (P < 0.01).  In summary, the investigation of abnormalities in B‐cell differentiation is a relatively simple and cheap approach for predicting relapse in precursor‐B‐ALL patients.