Assessment of minimal residual disease in childhood non-hodgkin lymphoma by polymerase chain reaction using patient-specific primers

Disseminated lymphoblastic lymphoma in children and adolescents: results of the COG A5971 trial: a report from the Children's Oncology Group

The Children's Oncology Group's A5971 trial examined central nervous system (CNS) prophylaxis and early intensification in paediatric patients diagnosed with CNS-negative Stage III and IV lymphoblastic lymphoma. Using a 2 × 2 factorial design, the study randomized patients to Children's Cancer Group (CCG) modified Berlin-Frankfurt-Muenster (BFM) acute lymphoblastic leukaemia (ALL) regimen with intensified intrathecal (IT) methotrexate (MTX) (Arm A1) or an adapted non-Hodgkin lymphoma/BFM-95 therapy with high dose MTX in interim maintenance but no IT-MTX in maintenance (Arm B1). Each cohort was randomized ± intensification (cyclophosphamide/anthracycline) (Arms A2/B2). For the 254 randomized patients, there was no difference in 5-year event-free survival (EFS) for the four arms: Arm A1, 80% [95% confidence interval (CI) 67-89%] and Arm A2, 81% (95% CI 69-89%); Arm B1, 80% (95% CI 68-88%) and Arm B2, 84% (95% CI 72-91%). The cumulative incidence of CNS relapse was 1·2%. Age <10 years and institutional imaging response at 2 weeks was associated with improved outcomes (P < 0·001 and P = 0·014 for overall survival). CNS positive patients (n = 12) did poorly [5-year EFS of 63% (95% CI 29-85%)]. For CNS-negative patients, there was no difference in outcome based on CNS prophylaxis (IT-MTX versus HD-MTX) or with intensification.

Outcome of newly diagnosed children and adolescents with localized lymphoblastic lymphoma treated on Children's Oncology Group trial A5971: a report from the Children's Oncology Group

BACKGROUND

Localized lymphoblastic lymphoma (LL) is rare in pediatric patients. We report the 5-year event-free survival (EFS) and overall survival (OS) for children and adolescents with localized LL treated on a uniform regimen based on Children's Cancer Group (CCG) leukemia therapy (COG A5971).

PROCEDURE

From June 2000 to October 2005, the study enrolled 60 patients >12 months old with Murphy stages I or II LL. Central review confirmed 56 eligible patients. Treatment consisted of 24 months of CCG BFM without day 28 intrathecal methotrexate in maintenance therapy or prophylactic cranial radiation.

RESULTS

Most patients had pre-B immunophenotype (75%). At a median follow-up of 5.9 years (range 1.4-9.3 years), the 5-year EFS was 90% [95% confidence interval (CI), 78-96%] and the 5-year OS was 96% (95% CI, 84-99%). Stage (I vs. II), immunophenotype, elevated LDH > institutional normal, or primary site did not impact outcome. Five relapses occurred-none in the CNS and none in patients with pre-T lymphoblastic disease. Patients tolerated treatment well with no toxic deaths.

CONCLUSION

Outcomes of pediatric patients with localized LL treated with 2 years of intensive acute lymphoblastic leukemia (ALL)-type therapy was excellent and is similar to the outcome for standard risk ALL treated less intensively. CNS prophylaxis was adequate with limited intrathecal methotrexate and no radiation. Future studies should identify biologic prognostic factors or biomarkers for pediatric patients with LL, explore less intensive treatment for patients with localized disease, and explore novel immunophenotype directed therapies.

Mitochondrial DNA in residual leukemia cells in cerebrospinal fluid in children with acute lymphoblastic leukemia

This feasibility study was designed to assess the ability to measure mitochondrial DNA (mtDNA) in cerebrospinal fluid (CSF) cells that contributed to minimal disease/persistent or residual disease (MD/PRD) from children with acute lymphoblastic leukemia (ALL). Increase in mtDNA copies in cancer cells has been suggested to play a role in MD/PRD. CSF as well as blood specimens from 6 children were assayed for MD/PRD and mtDNA copy numbers by quantitative real-time polymerase chain reaction. Of 7 MD/PRD-positive specimens, 6 had increased mtDNA copy numbers; while 11 MD/PRD-negative specimens had no increase in mtDNA copy numbers, p < 0.003. This is the first proof-of-concept study to measure mtDNA copy numbers in MD/PRD-positive CSF specimens from children with ALL. Increase of mtDNA copy numbers in MD/PRD childhood ALL cells and its significance as a mechanism for recurrence requires further investigation.

KEYWORDS

Minimal residual disease; Acute lymphoblastic leukemia; Central nervous system; Cerebrospinal fluid; Mitochondria.

Minimal disease assessment in the treatment of children and adolescents with intermediate-risk (Stage III/IV) B-cell non-Hodgkin lymphoma: a children's oncology group report

Children/adolescents with mature B-cell non-Hodgkin lymphoma (B-NHL) have an excellent prognosis but relapses still occur. While chromosomal aberrations and/or clonal immunoglobulin (Ig) gene rearrangements may indicate risk of failure, a more universal approach was developed to detect minimal disease (MD). Children/adolescents with intermediate-risk B-NHL were treated with French-British-American/Lymphome Malins de Burkitt 96 (FAB/LMB96) B4 modified chemotherapy and rituximab. Specimens from diagnosis, end of induction (EOI), and end of therapy (EOT) were assayed for MD. Initial specimens were screened for IGHV family usage with primer pools followed by individual primers to identify MD. Thirty-two diagnostic/staging specimens screened positive with primer pools and unique IGHV family primers were identified. Two patients relapsed; first relapse (4 months from diagnosis) was MD-positive at EOI, the second (36 months from diagnosis) was MD-positive at EOT. At EOI, recurrent rates were similar between the MRD-positive and MRD-negative patients (P = 0·40). At EOT, only 13/32 patients had MRD data available with one relapse in the MRD-positive group and no recurrences in the MRD-negative group (P = 0·077). The study demonstrated molecular-disseminated disease in which IgIGHV primer pools could be used to assess MD. This feasibility study supports future investigations to assess the validity and significance of MD screening in a larger cohort of patients with intermediate-risk mature B-NHL.

Minimal disseminated disease in childhood T-cell lymphoblastic lymphoma: a report from the children's oncology group

PURPOSE Disease dissemination to the bone marrow is detected at diagnosis in approximately 15% of children with T-cell lymphoblastic lymphoma (T-LL). It is unclear whether the remaining patients have submicroscopic systemic disease and, if so, what is the clinical significance of this finding. PATIENTS AND METHODS Using a flow cytometric method that can detect one T-LL cell among 10,000 normal cells, we examined bone marrow and peripheral-blood samples collected from 99 children with T-LL at diagnosis, as well as blood samples collected from 42 patients during treatment. Results In 71 (71.7%) of the 99 marrow samples obtained at diagnosis, T-LL cells represented 0.01% to 31.6% (median, 0.22%) of mononuclear cells; 57 of the 71 T-LL-positive samples were from patients with stage II/III disease. Results of studies in bilateral marrow aspirates were highly concordant. Two-year event-free survival (EFS) was 68.1% +/- 11.1% (SE) for patients with > or = 1% T-LL cells in bone marrow versus 90.7% +/- 4.4% for those with lower levels of marrow involvement (P = .031); EFS for patients with > or = 5% lymphoblasts was 51.9% +/- 18.0% (P = .009). T-LL cells were as prevalent in blood as in marrow; monitoring residual T-LL cells in blood during remission induction therapy identified patients with slower disease clearance. CONCLUSION More than two thirds of children with T-LL have disseminated disease at diagnosis, a proportion much higher than previously demonstrated. Measurements of disease dissemination at diagnosis might provide useful prognostic information, which can be further refined by monitoring response to therapy through blood testing.

Screening for residual disease in pediatric burkitt lymphoma using consensus primer pools

Assessing molecular persistent or minimal residual disease (PD/MRD) in childhood Burkitt lymphoma (BL) is challenging because access to original tumor is usually needed to design patient-specific primers (PSPs). Because BL is characterized by rearranged immunoglobulin heavy chain (IgV_H) genes, IgV_H primer pools from IgV_H1–IgV_H7 regions were tested to detect PD/MRD, thus eliminating the need for original tumor. The focus of the current study was to assess the feasibility of using IgV_H primer pools to detect disease in clinical specimens. Fourteen children diagnosed with B-NHL had follow-up repository specimens available to assess PD/MRD. Of the 14 patients, 12 were PD/MRD negative after 2 months of therapy and remained in remission at the end of therapy; 2/14 patients were PD/MRD positive at 2-3 months and later relapsed. PSP-based assays from these 14 patients showed 100% concordance with the current assay. This feasibility study warrants further investigation to assess PD/MRD using IgV_H primer pools, which could have clinical significance as a real-time assessment tool to monitor pediatric BL and possibly other B-cell non-Hodgkin lymphoma therapy.

Bone marrow minimal disseminated disease (MDD) and minimal residual disease (MRD) in childhood T-cell lymphoblastic lymphoma stage III, detected by flow cytometry (FC) and real-time quantitative polymerase chain reaction (RQ-PCR)

BACKGROUND

Despite overlapping features of T-cell lymphoblastic lymphoma (T-LLy) and T-cell acute lymphoblastic leukemia (T-ALL), which respond favorably to T-ALL treatment, clinical and biological differences exist. We retrospectively assessed the prevalence of submicroscopic bone marrow (BM) minimal disseminated disease (MDD) at diagnosis and the early response to treatment (minimal residual disease--MRD) and their prognostic significance in 17 children with stage III T-LLy treated according to Berlin-Frankfurt-Munster (BFM) non-Hodgkin lymphoma protocols.

PROCEDURE

Four-color flow cytometry (FC) was used for lymphoma associated immunophenotype and real-time quantitative polymerase chain reaction (RQ-PCR) for T-cell receptor (TCR beta/delta/gamma) gene rearrangements with at least 0.01% sensitivity.

RESULTS

Two markers per patient were identified in all cases using FC and in 80% using RQ-PCR. BM MDD at diagnosis of >or=0.01% was detected by FC and RQ-PCR in 88% and 80% of patients, respectively, and by at least one of the methods in all patients. A significant correlation was achieved between the methods by Pearson correlation analysis (P = 0.004). MRD levels significantly decreased to very low levels on day 33 in 9 out of 10 patients studied. The only patient that remained positive relapsed.

CONCLUSIONS

MDD was prevalent in stage III T-LLy, for which we could not prove a prognostic significance in the context of ALL-like treatment. This study shows that both FC and RQ-PCR methods are efficient for MDD and MRD analyses in T-LLy.

Chemotoxicity recovery of mitochondria in non-Hodgkin lymphoma resulting in minimal residual disease

BACKGROUND

The mechanisms responsible for resistant disease or recurrence of non-Hodgkin lymphoma (NHL) in children cover a wide spectrum from drug resistance to genetic mutations. A unique mechanism suggesting the role of mitochondria as the key energy source is studied following a clinical observation where pediatric Burkitt lymphoma (BL) specimens from patients on therapy were found to have increased copies of mitochondria DNA (mtDNA) in specimens which were shown to be positive for minimal residual disease and/or persistent disease (MRD/PD). This study hypothesized that the mitochondria play an important role in a cell's recovery from toxicity via a compensatory increase in mtDNA.

PROCEDURE

BL specimens with MRD/PD were assayed for mtDNA. An in vitro model was then designed using Ramos cell lines by exposing the lymphoma cells to varying concentrations of doxorubicin and vincristine for 1 hr; and allowing for recovery in culture over 7 days. DNA was extracted from aliquots over several days to determine mtDNA copy numbers by real-time polymerase chain reaction (PCR).

RESULTS

Increased mtDNA copy numbers were found in clinical specimens with MRD/PD as well as in recovering Ramos cells from chemotoxicity.

CONCLUSIONS

The recovering lymphoma cells from the chemotoxic effects appeared to compensate by increasing mtDNA content, which may contribute to the clinical residual or resistant disease in some cases of childhood BL.

Comparative investigations of T cell receptor gamma gene rearrangements in frozen and formalin-fixed paraffin wax-embedded tissues by capillary electrophoresis

AIM

To compare clonal T cell receptor gamma (TCRgamma) gene rearrangements in frozen and formalin-fixed paraffin wax-embedded (FFPE) tissue, using capillary electrophoresis for use in diagnostics, as T cell lymphomas may be difficult to diagnose by conventional methods.

METHODS

The DNA for PCR was extracted from frozen and FFPE tissue, cell lines and blood. PCR primers Vgamma1-8, Vgamma9, Vgamma10 or Vgamma11 (5' end labelled) combined with a mixture of JgammaP1/JgammaP/JgammaP2/Jgamma2 (unlabelled) were used. Monoclonal cases were sequenced and clonality, reproducibility, sensitivity and specificity analyses were carried out.

RESULTS

In all cases the molecular test was found to be in agreement with the histological diagnosis. Discrepancies were found between frozen and FFPE tissue in 18 of 56 (32%) tests. The method was highly reproducible. The sensitivity was found to be 0.5% for cell lines and 1% for patient specimens and the specificity 100%. The junctional region between the Vgamma and Jgamma segments was specific for each patient.

CONCLUSIONS

Capillary electrophoresis of PCR products from frozen and FFPE tissue is suitable for detecting clonal TCRgamma gene rearrangements. It is important, however, to correlate the results with conventional morphological and immunohistochemical studies.

Continuing challenges in childhood non-Hodgkin's lymphoma

Non-Hodgkin's lymphoma in children includes a number of different pathological subtypes and, with improved diagnostic techniques and better understanding of the natural history of each type, treatment strategies have become more tumour-specific. Original staging systems are now less useful in determining treatment stratification and there is a need for careful analysis of large cohorts of patients, treated in the same manner, to determine the clinical and biological features that, with current therapies, are of prognostic value. Novel imaging techniques, such as positron emission tomography, and molecular techniques to detect low-level marrow involvement are likely to be incorporated into new risk grouping. These will be used to determine the extent of initial disease and evaluate more accurately the speed and quality of response to chemotherapy. With high cure rates, it becomes particularly important to minimize late effects of therapy and the introduction of monoclonal antibodies in combination with chemotherapy may provide a method for improving outcome in poor risk groups and reducing sequelae by allowing reduction in chemotherapy in good risk patients.

Assessing immunoglobulin heavy chain rearrangements in pediatric CD20-positive and CD20-negative classic Hodgkin's disease

Approximately 15% of all cases of childhood classical Hodgkin's disease (HD) express CD20, a B-cell marker associated with immunoglobulin heavy chain rearrangements. Immunoglobulin heavy chain rearrangements in Reed-Sternberg cells could be used to assess minimal residual disease (MRD), as was shown with immunoglobulin heavy chain patient-specific primers (PSPs) in non-Hodgkin's lymphoma. The aim of this study was to analyze pediatric HD for future design of immunoglobulin heavy chain PSP for MRD detection. DNA was extracted from paraffin-embedded tissue from unstained slides of 8 pediatric CD20+ nodular sclerosis HD cases and 10 CD20-nodular sclerosis HD cases. Immunoglobulin heavy chain polymerase chain reaction and sequencing were performed on 16 of 18 cases, which had adequate DNA for further analysis. Sequence analysis from 3 cases (19% of HD cases) demonstrated unique V(D)J regions, which could potentially be used to design PSP. Unique PSPs could be used to assess MRD in advanced-stage HD specimens. Future studies should focus on improved detection and analysis of more cases to identify appropriate specimens in assessing clinical implications of MRD detection.