Biallelic IgH rearrangements in patients with indolent lymphoproliferative disorders: Molecular and practical implications

Rituximab based therapy followed by autologous stem cell transplantation leads to superior outcome and high rates of PCR negativity in patients with indolent B-cell lymphoproliferative disorders

Autologous stem cell transplantation (ASCT) and rituximab based therapy represent effective treatments of indolent B-cell lymphoproliferative disorders (B-LPDs) that often induce molecular remission (MR). We assessed the impact of MR after treatment on prognosis of 57 patients with indolent B-LPDs. We also evaluated the impact of therapy on patients' outcome. Failure to achieve MR was identified as an independent risk factor regardless of treatment modality. PCR positive patients had shorter progression free survival (PFS) in contrast with patients in MR after rituximab (median 0.75 and 2.5 years respectively; p=0.006) or patients in MR after rituximab followed by ASCT (median 3.3 years; p=0.0032). PCR positive patients had a 5-year overall survival (OS) of only 40% compared to a 5-year OS of 76% for PCR negative patients after rituximab (p=0.0186) and 86% PCR negative patients after rituximab with ASCT (p=0.003). All nine patients transplanted with PCR positive graft relapsed (p=0.0023) with shorter PFS (p=0.0008). Rituximab based therapy induced MR in 25 (64%) compared to 18 (100%) patients after rituximab followed by ASCT (p=0.0025). We observed no difference in PFS between the transplant group (3.3 years) and rituximab based treatment (1.9 years), but the 5-year OS of patients with transplant was 85 and 59% respectively (p=0.0271). Patients with indolent B-LPDs who achieve MR have better prognosis. Rituximab based therapy induces MR in high number of patients, which can be further improved by ASCT and patients have an excellent outcome. PCR positive harvest represents a high risk of relapse after ASCT.

Development of the polymerase chain reaction assay based on the canine genome database for detection of monoclonality in B cell lymphoma

From the canine genome database and its bioinformatic analysis, we identified conserved sequences within the vast majority of 61 variable segments and 1 joining segment of the immunoglobulin heavy chain (IgH) gene, and designed optimal primers for polymerase chain reaction (PCR) amplification directed at these conserved sequences to evaluate the monoclonality of IgH in canine B cell lymphoma. Using the primers, a PCR-based assay was performed on fine-needle aspiration samples of normal, hyperplasia, and malignant lymph nodes and lymphoma cell lines. All fine-needle aspiration samples of five B cell lymphoma cases and the B cell lymphoma line GL-1 exhibited clonal amplification, whereas no amplification was observed in the samples from normal and hyperplasia lymph nodes, cases of T cell lymphoma, and the T cell lymphoma line CL-1. The primers we designed clearly distinguished malignant B lymphocytes from normal, reactive, and malignant T lymphocytes, indicating a potential utility of the primers for PCR-based routine clinical examination for canine B cell lymphoma.