Jacqueline Van Den Akker

Mechanisms of genesis of variant translocation in chronic myeloid leukemia are not correlated with ABL1 or BCR deletion status or response to imatinib therapy

Many published studies have indicated that various mechanisms could be involved in the genesis of variant chronic myelogeneous leukemia (CML) translocations. These are mainly one-step or two-step mechanisms, associated or not with deletions adjacent to the translocation junction on der(9) or der(22) chromosomes (or both). Based on the mechanism of genesis, it has been suggested that the complexity may affect the occurrence of ABL1 and BCR deletions (either or both), or may be associated with the CML disease course, and thus could determine the response to imatinib therapy. Through a retrospective molecular cytogenetic study of 41 CML patients with variant Philadelphia chromosome (Ph), we explored the genesis of these variant rearrangements and analyzed the correlation with deletion status and imatinib efficiency. Our results confirmed that the one-step mechanism is the most frequent, evidenced in 30 of 41 patients (73%); 3 patients demonstrated other more complex multistep events and 8 patients (19.5%) harbored ABL1 or BCR deletions that are not significantly associated with the complexity of translocation genesis. We also found no association between one-step, two-step, or multistep mechanisms and the response to imatinib therapy.

Importance of marrow dose on posttransplant outcome in acute leukemia: Models derived from patients autografted with mafosfamide-purged marrow at a single institution

Several prospective randomized trials in acute myelocytic leukemia (AML) documented a lower relapse rate with autologous bone marrow transplantation (ABMT) than with conventional chemotherapy. However, they also identified some transplant difficulties, such as failure to collect sufficient numbers of stem cells, slow kinetics of engraftment, and a high transplant-related mortality that diminished or negated positive impact on overall survival. Data for ABMT are inconclusive in acute lymphocytic leukemia (ALL) in adults. We retrospectively analyzed patients with acute leukemia autografted with marrow purged with mafosfamide after January 1983 in our institution. The population comprised 229 consecutive patients; 165 with AML [123 in first remission (CR1), 32 in second remission (CR2)]; 61 with ALL (46 in CR1, 4 in CR2); and 3 with undifferentiated acute leukemia. All patients were autografted with marrow purged with mafosfamide. Mafosfamide was given at a constant dose of 50 microg/mL in 103 and adjusted individually to produce a CFU-GM LD 95 (5% residual CFU-GM post purging) in 126. The outcome was analyzed for correlation with patient characteristics, the disease including cytogenetics, and the graft itself. Prognostic factors identified by multivariate analysis were used to derive a prognostic classification. Patients receiving higher doses of marrow submitted to purging (>5.46 x 10(4) CFU-GM/kg) experienced a lower treatment-related mortality (RR = 0.11, p = 0.005) and a higher leukemia-free (RR = 0.5, p = 0.005) and overall survival (RR = 0.4, p = 0.001). Patients receiving <0.004% CFU-GM of marrow actually infused post purging had a lower relapse rate (RR = 0.51, p = 0.003). Modeling of prognostic groups identified good-, intermediate-, and poor-risk categories. Patients receiving a stem cell dose evaluated before purging of >5.46 x 10(4) CFU-GM/kg and doses actually infused post purging of < or =0.02 x 10(4)/kg had a treatment-related mortality of only 2+/-2%, a leukemia-free survival of 70%, and an overall survival of 77+/-7% at 10 years. In this study of autotransplantation for acute leukemia using mafosfamide-purged marrow, the stem cell dose used for purging and the intensity of purging were the most important factors predicting outcome.

Two new cases of papillary renal cell carcinoma with t(X;1)(p11;q21) in females.

Two cases of papillary renal cell carcinoma (RCC) with a karyotype 46,X,t(X;1)(p11.2;q21) in two female patients aged 9 and 29 years are reported. These observations, and the review of the 17 reported cases with a translocation at band Xp11 confirm that this abnormality delineates a clinicopathological entity within the classical papillary RCC, characterized by the early age of occurrence and, probably, distinct histological features. Including these two new female cases, the sex ratio in cases with t(X;1) appears similar to that observed in the other papillary RCC.

Reassessment of childhood B-lineage lymphoblastic leukemia karyotypes using spectral analysis

We studied a stratified cohort of 51 childhood B‐lineage acute lymphoblastic leukemias (B‐ALLs) to evaluate the efficiency of spectral karyotyping (SKY) in the detection of chromosome aberrations previously diagnosed using chromosome banding and/or reverse transcriptase polymerase chain reaction. Despite the small number of cases analyzed, several important features emerge from the study: (a) The result of banding analysis was revised in two‐thirds of the cases. Eighty‐three chromosome anomalies previously undetected or not characterized using chromosome banding were identified by spectral karyotyping, even in patients with apparently normal karyotypes. (b) All hyperdiploidy cases showed one or more extra copies of chromosomes X, 14, and 21. (c) Two hidden rearrangements, a t(7;12)(?p12;p13), and a new translocation, a t(9;12)(q31;p13), both involving the TEL gene, were characterized. (d) Some cryptic rearrangements, such as the der(21) t(12;21) translocation, remained undetected. (e) No new recurrent chromosome anomalies were discovered with this technique. In conclusion, the present study confirms the efficiency of the SKY technique in resolving and characterizing many complex chromosome anomalies seen in childhood B‐ALLs, but it raises questions about the ability of this technique to detect cryptic rearrangements, such as the t(12;21) translocation.

Serum‐free liquid marrow culture in patients with acute lymphoblastic leukaemia: a potential application to purge marrow for autologous transplantation

Summary. We have previously established a serum‐free (SF) culture medium, which supports normal haemopoietic progenitor cell growth for at least 4 weeks as does conventional serum dependent (SD) medium. In the present study, we investigated the efficacy of such a defined SF liquid medium which sustained in vitro residual normal haemopoietic proliferation of marrow derived from ALL patients and which was detrimental for the leukaemic population. Evidence for a potential selective effect of SF culture was obtained by a leukaemic progenitor cell assay (ALL‐CFU) and the detection of the bcr/abl translocation by polymerase chain reaction (PCR). In 13 experiments including 12 patients, morphological blast cells and ALL‐CFU were dramatically reduced within 3 weeks of incubation in both SF and SD cultures. Likewise, in 5/5 experiments in SD and 2/5 experiments in SF conditions, leukaemic cells expressing the bcr/abl fusion gene disappeared within 3–4 weeks. In contrast, the absolute numbers of supernatant cells harvested weekly from SF and SD cultures were similar. No difference in CFU‐GM production was detected for the two culture systems. Erythropoiesis in SF medium exhibited a slower decline than that found in SD. These results indicate that liquid marrow culture may selectively deplete leukaemic lymphoblastic cells and enable repopulation by residual normal haemopoietic cells. This technique may be useful to purge leukaemic cells for clinical autologous bone marrow transplantation in patients with ALL.