Karin E. Summers

Frequency of the Bcl-2/IgH Rearrangement in Normal Individuals: Implications for the Monitoring of Disease in Patients With Follicular Lymphoma

PURPOSE To determine the incidence and frequency of the Bcl-2/IgH rearrangement in the peripheral blood of normal individuals to define the potential complication this may pose for the molecular monitoring of disease in patients with follicular lymphoma (FL). MATERIALS AND METHODS The incidence and frequency of the major breakpoint cluster region rearrangement in DNA extracted from peripheral blood or lymphoblastoid cell lines from 481 normal individuals was determined using a TaqMan real-time polymerase chain reaction assay (PE Applied Biosystems, Foster City, CA). RESULTS Twenty three percent of samples were positive for the Bcl-2/IgH rearrangement, with approximately 3% of these at levels of more than 1 in 10(4) cells. CONCLUSION The presence of circulating Bcl-2/IgH+ cells, other than those derived from the malignant clone, could confound the detection and quantitation of minimal residual disease in patients with FL, particularly at low levels of tumor burden.

A UK multicentre phase II study of rituximab (chimaeric anti‐CD20 monoclonal antibody) in patients with follicular lymphoma, with PCR monitoring of molecular response

Follicular lymphoma (FL) cells express CD20 and are associated in most cases with the t(14;18) chromosomal translocation. A multicentre study was undertaken between January 1997 and January 1998 to assess the complete response rate (CR) and overall response rate (RR) to rituximab, a chimaeric anti‐CD20 monoclonal antibody. Seventy patients with previously treated FL received rituximab (375 mg/m2/week ×4, by intravenous infusion). Restaging studies were performed 1 and 2 months after therapy. Molecular monitoring for the presence of cells harbouring the Bcl‐2/JH gene rearrangement in the peripheral blood (PB) and bone marrow (BM) was performed before and after treatment using a two‐step semi‐nested polymerase chain reaction (PCR) assay. The overall RR was 32/70 (46%), being highest in patients who had received only one previous treatment (12/15, 80%). However, only two patients achieved a CR. The median duration of response was 11 months. Thirteen of 21 evaluable ‘PCR‐positive’ patients (62%) became ‘PCR‐negative’ in PB and/or BM samples 1 month after rituximab, although this did not correlate with clinical response. Treatment was generally well tolerated, although one patient developed Stevens–Johnson syndrome. Rituximab was shown to be active in FL, and in some cases PB and/or BM became PCR negative. Studies in combination with cytotoxic chemotherapy to increase the CR rate are warranted.

Quantitative PCR Analysis for Bcl-2/IgH in a Phase III Study of Yttrium-90 Ibritumomab Tiuxetan As Consolidation of First Remission in Patients With Follicular Lymphoma

PURPOSE The randomized First-Line Indolent Trial (FIT) was conducted in patients with advanced follicular lymphoma (FL), to evaluate the safety and efficacy of yttrium-90 ((90)Y) ibritumomab tiuxetan given as consolidation of complete or partial remission. This study of minimal residual disease was undertaken in parallel, to determine the rate of conversion from bcl-2 polymerase chain reaction (PCR) -detectable to -undetectable status and the corresponding effect on progression-free survival (PFS). PATIENTS AND METHODS Blood samples from 414 patients ((90)Y-ibritumomab, n = 208; control, n = 206) were evaluated using real-time quantitative polymerase chain reaction (RQ-PCR); 186 were found to have the bcl-2 rearrangement and were thus eligible for inclusion in the RQ-PCR analysis. Results Overall, 90% of treated patients converted from bcl-2 PCR-detectable to -undetectable disease status, compared with 36% in the control group. Treatment significantly prolonged median PFS in patients converting to bcl-2 PCR-undetectable status (40.8 v 24.0 months in the control group; P < .01, hazard ratio [HR], 0.399). In patients who had bcl-2 PCR-detectable disease at random assignment, treatment significantly prolonged median PFS (38.4 v 8.2 months in the control group; P < .01, HR, 0.293). CONCLUSION Eradication of PCR-detectable disease occurred more frequently after treatment with (90)Y-ibritumomab tiuxetan and was associated with prolongation of PFS.

Reliable detection of clonal IgH/Bcl2 MBR rearrangement in follicular lymphoma: methodology and clinical significance

The prognostic significance of IgH/Bcl2 rearrangement in follicular lymphoma (FL) remains contentious; polymerase chain reaction (PCR) methodology and tissue source variability may account for some inconsistencies. As IgH/Bcl2 major breakpoint region (MBR) sequences may be found in normal blood, an MBR+ result by conventional PCR in blood/bone marrow may not indicate FL. To establish tumour MBR status, 190 lymphoid tissue samples with histologically evident FL (and therefore >1% tumour cells) were examined by real‐time quantifiable PCR; 50% (95/190) had clonal MBR IgH/Bcl2 (MBR was considered clonal when >1%). Overall survival (median = 11·5 years) of MBR+ and MBR− patients was not significantly different.

The relative role of peripheral blood and bone marrow for monitoring molecular evidence of disease in follicular lymphoma by quantitative real‐time polymerase chain reaction

Summary.  Peripheral blood (PB) and bone marrow (BM) are used interchangeably for t(14;18) (IgH/BCL‐2) molecular monitoring in follicular lymphoma (FL) and detection of rearrangement after treatment has been correlated to increased risk of relapse. To determine the relative value of each tissue, MBR t(14;18) was quantified by real‐time polymerase chain reaction in 52 simultaneous paired PB and BM samples from 38 FL patients. In total, 79% of sample pairs taken in remission (n = 19) or when no morphological disease was evident in the BM (n = 29) had t(14;18) copy number within one log difference and the median difference was small. These findings suggest that, in remission, PB may be adequately monitored. In general, however, higher copy number was detected in BM than in the corresponding PB sample.

WTX is rarely mutated in acute myeloid leukemia.

WTX (Wilms’ tumor gene on the X chromosome) is inactivated in 30% of Wilms’ tumors, mostly by chromosomal deletion.[1][1] The WTX protein is a component of the β-catenin destruction complex and promotes its ubiquitination and degradation, functioning as a negative regulator of WNT/β-catenin