Calcium and cholecalciferol supplementation provides no added benefit to nutritional counseling to improve bone mineral density in survivors of childhood acute lymphoblastic leukemia (ALL)

BACKGROUND

We sought to improve lumbar spine bone mineral density (LS-BMD) in long-term survivors of childhood acute lymphoblastic leukemia (ALL) using calcium and cholecalciferol supplementation.

PROCEDURE

This double-blind, placebo-controlled trial randomized 275 participants (median age, 17 [9-36.1] years) with age- and gender-specific LS-BMD Z-scores <0 to receive nutritional counseling with supplementation of 1,000 mg/day calcium and 800 International Unit cholecalciferol or placebo for 2 years. The primary outcome was change in LS-BMD assessed by quantitative computerized tomography (QCT) at 24 months. Linear regression models were employed to identify the baseline risk factors for low LS-BMD and to compare LS-BMD outcomes.

RESULTS

Pre-randomization LS-BMD below the mean was associated with male gender (P = 0.0024), White race (P = 0.0003), lower body mass index (P < 0.0001), and cumulative glucocorticoid doses of ≥ 5,000 mg (P = 0.0012). One hundred eighty-eight (68%) participants completed the study; 77% adhered to the intervention. Mean LS-BMD change did not differ between survivors randomized to supplements (0.33 ± 0.57) or placebo (0.28 ± 0.56). Participants aged 9-13 years and those 22-35 years had the greatest mean increases in LS-BMD (0.50 ± 0.66 and 0.37 ± 0.23, respectively). Vitamin D insufficiency (serum 25[OH]D <30 ng/ml) found in 296 (75%), was not associated with LS-BMD outcomes (P = 0.78).

CONCLUSION

Cholecalciferol and calcium supplementation provides no added benefit to nutritional counseling for improving LS-BMD among adolescent and young adult survivors of ALL (93% of whom had LS-BMD Z-scores above the mean at study entry).

Frequent mutations in SH2D1A (XLP) in males presenting with high-grade mature B-cell neoplasms

X-linked lymphoproliferative syndrome (XLP) is caused by mutations in SH2D1A, and is associated with overwhelming infectious mononucleosis, aplastic anemia, hypogammaglobulinemia, and B-cell lymphomas. However, the frequency of SH2D1A mutations in males who present with B NHL is unknown. Five cases of XLP were diagnosed among 158 males presenting with B NHL (approximately 3.2%). Four of the patients had two episodes of B NHL and one had a single episode of B NHL followed by aggressive infectious mononucleosis. Prospective screening for XLP in males with B-cell lymphoma at the time of initial diagnosis should be considered.

ETV6-RUNX1-positive childhood acute lymphoblastic leukemia: improved outcome with contemporary therapy

ETV6-RUNX1 fusion is the most common genetic aberration in childhood acute lymphoblastic leukemia (ALL). To evaluate whether outcomes for this drug-sensitive leukemia are improved by contemporary risk-directed therapy, we studied clinical features, response and adverse events of 168 children with newly diagnosed ETV6-RUNX1-positive ALL on St Jude Total Therapy studies XIIIA (N=36), XIIIB (N=38) and XV (N=94). Results were compared with 494 ETV6-RUNX1-negative B-precursor ALL patients. ETV6-RUNX1 was associated with age 1-9 years, pre-treatment classification as low risk and lower levels of minimal residual disease (MRD) on day 19 of therapy (P<0.001). Event-free survival (EFS) or overall survival (OS) did not differ between patients with or without ETV6-RUNX1 in Total XIIIA or XIIIB. By contrast, in Total XV, patients with ETV6-RUNX1 had significantly better EFS (P=0.04; 5-year estimate, 96.8±2.4% versus 88.3±2.5%) and OS (P=0.04; 98.9±1.4% versus 93.7±1.8%) than those without ETV6-RUNX1. Within the ETV6-RUNX1 group, the only significant prognostic factor associated with higher OS was the treatment protocol Total XV (versus XIIIA or XIIIB) (P=0.01). Thus, the MRD-guided treatment schema including intensive asparaginase and high-dose methotrexate in the Total XV study produced significantly better outcomes than previous regimens and demonstrated that nearly all children with ETV6-RUNX1 ALL can be cured.

MN1 overexpression is an important step in the development of inv(16) AML

The gene encoding the transcriptional co-activator MN1 is the target of the reciprocal chromosome translocation (12;22)(p13;q12) in some patients with acute myeloid leukemia (AML). In addition, expression array analysis showed that MN1 was overexpressed in AML specified by inv(16), in some AML overexpressing ecotropic viral integration 1 site (EVI1) and in some AML without karyotypic abnormalities. Here we describe that mice receiving transplants of bone marrow (BM) overexpressing MN1 rapidly developed myeloproliferative disease (MPD). This BM also generated myeloid cell lines in culture. By mimicking the situation in human inv(16) AML, forced coexpression of MN1 and Cbfbeta-SMMHC rapidly caused AML in mice. These findings identify MN1 as a highly effective hematopoietic oncogene and suggest that MN1 overexpression is an important cooperative event in human inv(16) AML.

Molecular emergence of acute myeloid leukemia during treatment for acute lymphoblastic leukemia

Therapy-related acute myeloid leukemias (t-AML) with translocations of the MLL gene are associated with the use of topoisomerase II inhibitors. We established the emergence of the malignant clone in a child who developed t-AML with a t(11;19) (q23;p13.3) during treatment for acute lymphoblastic leukemia (ALL). The MLL-ENL and the reciprocal ENL-MLL genomic fusions and their chimeric transcripts were characterized from samples collected at the time of t-AML diagnosis. We used PCR with patient-specific genomic primers to establish the emergence of the MLL-ENL fusion in serially obtained DNA samples. The MLL-ENL fusion was not detectable in bone marrow at the time of ALL diagnosis or after 2 months of chemotherapy (frequency <8.3 x 10(-7) cells(-1)). The genomic fusion was first detected in bone marrow after 6 months of treatment at a frequency of one in 4,000 mononuclear bone marrow cells; the frequency was one in 70 cells after 20 months of therapy. At the first detection of MLL-ENL, the only topoisomerase II inhibitors the patient had received were one dose of daunorubicin and two doses of etoposide. The MLL-ENL fusion was not detectable in blood at the time of ALL diagnosis or after 0.7, 2, 8, 10, and 12 months of therapy but was detectable in blood at 16 months (one in 2.3 x 10(4) cells). Recombinogenic Alu sequences bracketed the breakpoints in both fusions. These data indicate that the malignant clone was not present before therapy, arose early during chemotherapy, and was able to proliferate even during exposure to antileukemic therapy.

The t(12;21) translocation converts AML-1B from an activator to a repressor of transcription

The t(12;21) translocation is present in up to 30% of childhood B-cell acute lymphoblastic and fuses a potential dimerization motif from the ets-related factor TEL to the N terminus of AML1. The t(12;21) translocation encodes a 93-kDa fusion protein that localizes to a high-salt- and detergent-resistant nuclear compartment. This protein binds the enhancer core motif, TGTGGT, and interacts with the AML-1-binding protein, core-binding factor beta. Although TEL/AML-1B retains the C-terminal domain of AML-1B that is required for transactivation of the T-cell receptor beta enhancer, it fails to activate transcription but rather inhibits the basal activity of this enhancer. TEL/AML-1B efficiently interferes with AML-1B dependent transactivation of the T-cell receptor beta enhancer, and coexpression of wild-type TEL does not reverse this inhibition. The N-terminal TEL helix-loop-helix domain is essential for TEL/AML-1B-mediated repression. Thus, the t(12;21) fusion protein dominantly interferes with AML-1B-dependent transcription, suggesting that the inhibition of expression of AML-1 genes is critical for B-cell leukemogenesis.