• In vitro cellular drug resistance adds prognostic information to other known risk-factors in childhood acute lymphoblastic leukemia.

      Lönnerholm, Gudmar; Thörn, Ingrid; Sundström, Christer; Frost, Britt-Marie; Flaegstad, Trond; Heyman, Mats; Jonsson, Olafur Gisli; Harila-Saari, Arja; Madsen, Hans O; Porwit, Anna; et al. (Pergamon Press, 2011-04)
      Leukemic cells from 230 children with newly diagnosed B-cell precursor ALL were tested for in vitro drug resistance to a panel of anti-cancer drugs. Minimal residual disease (MRD) was measured by RQ-PCR. During follow-up, 24 relapses occurred in the 159 children with MRD <0.1% day 29. The risk of any relapse was correlated to vincristine and doxorubicin resistance, with a relative risk of 3.7 (95% CI 1.3-10.5; p=0.016) for patients resistant to both drugs. There was a significant correlation also for the subgroup with extra-medullary relapses. Our findings indicate that analysis of drug resistance can add prognostic information to other known risk-factors including MRD.
    • Quantifying the role of aberrant somatic hypermutation in transformation of follicular lymphoma.

      Halldórsdóttir, Anna Margrét; Frühwirth, Margareta; Deutsch, Alexander; Aigelsreiter, Ariane; Beham-Schmid, Christine; Agnarsson, Bjarni A; Neumeister, Peter; Richard Burack, W; Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA. (Pergamon Press, 2008-07-01)
      Somatic hypermutation (SHM) aberrantly targets proto-oncogenes in various non-Hodgkin's lymphoma. To test the association of SHM with transformation of follicular lymphoma (FL), we sequenced mutational hot spots in five proto-oncogenes (BCL6, PAX5, RHOH, MYC and PIM1) in 32 low-grade FL (lgFL) with follicular histology and 26 transformed FL (tFL) with diffuse large cell histology. No difference was detected in the fraction of specimens mutated (75% of lgFL and 77% of tFL) or in the mutation load (0.08 for lgFL vs. 0.06mutations/100bp/allele for tFL). Serial specimens were examined from 25 patients showing stable low-grade FL (slgFL; n=6) or a low-grade FL that later transformed into diffuse large cell lymphoma (tFL; n=19). slgFL and tFL patients accumulated similar numbers of mutations in the interval between biopsies. These data indicate that mutations attributable to aberrant SHM occur with similar frequency in low-grade and transformed FL; transformation is not associated with a higher rate of aberrant SHM. Moreover, the frequency of mutations attributable to aberrant SHM in tFL was significantly lower than that reported for de novo diffuse large B cell lymphoma, suggesting differing oncogenic mechanisms in transformed follicular lymphoma and de novo diffuse large B cell lymphoma.