Myeloma clonotypic B cells are hampered in their ability to undergo B-cell differentiation in vitro

In the peripheral blood (PB) of multiple myeloma (MM) patients, clonotypic B cells are present that express the identical V(D)J rearrangements as the malignant plasma cells in the bone marrow. In the present study, the proliferative capacity of clonotypic B cells from MM patients (n = 10) and the ability to differentiate in vitro was determined using the CD40-culturing system. For six patients, the presence of clonotypic B cells expressing variant immunoglobulin (Ig) isotypes was assessed by Ig isotype-specific allele-specific oligonucleotide reverse transcription polymerase chain reaction (ASO-RT-PCR) after culturing with CD40L and interleukin 4 (IL-4). In three out of six patients, clonotypic B cells expressing variant isotypes were detected both before and after culturing. The ability of clonotypic B cells to undergo B-cell differentiation was studied by abrogating CD40 signalling accompanied by IL-10 and IL-2 stimulation, enhancing differentiation towards Ig-secreting cells. The numbers of clonotypic B cells were determined by quantitative ASO-PCR. An increase in cell number was observed upon CD40L and IL-4 stimulation, whereas the relative number of clonotypic B cells was unaltered. In contrast, upon B-cell differentiation the relative number of clonotypic B cells decreased. In conclusion, clonotypic B cells can be cultured and isolated in vitro using the CD40 system. Clonotypic B cells responded to CD40 triggering in a similar fashion as to non-clonotypic normal B cells. However, the ability of clonotypic B cells to undergo in vitro activation and differentiation into Ig-secreting cells is hampere

Clofarabine added to intensive treatment in adult patients with newly diagnosed ALL: the HOVON-100 trial.

Clofarabine (CLO) is a nucleoside analogue with efficacy in relapsed/refractory acute lymphoblastic leukemia (ALL). This randomized phase III study aimed to evaluate whether CLO added to induction and consolidation would improve outcome in adults with newly diagnosed ALL. Treatment for younger (18-40 years) patients consisted of a pediatric inspired protocol and for older patients (41-70 years) of a semi-intensive protocol was used. 340 patients were randomized. After a median follow up of 70 months, 5-year EFS was 50% and 53% for arm A and B (CLO arm). For patients ≤40 years, EFS was 58% vs 65% in arm A vs B, while in patients >40 years EFS was 43% in both arms. CR rate was 89% in both arms and similar in younger and older patients. Minimal residual disease (MRD) was assessed in 200 patients (60%). Fifty-four of 76 evaluable patients (71%) were MRD negative after consolidation 1 in arm A vs 75/81 (93%) in arm B (p=0.001). Seventy (42%) patients proceeded to allogeneic hematopoietic stem cell transplantation in both arms. Five years OS was similar in both arms, 60% vs 61%. Among patients achieving CR, relapse rates were 28% and 24%, and non-relapse mortality was 16% vs 17% after CR. CLO treated patients experienced more serious adverse events, more infections, and more often went off-protocol. This was most pronounced in older patients. We conclude that, despite a higher rate of MRD-negativity, addition of CLO does not improve outcome in adults with ALL, which might be due to increased toxicity. The trial is registered at www.trialregister.nl as NTR2004