Deletion of chromosome 13 detected by conventional cytogenetics is a critical prognostic factor in myeloma

In myeloma, the prognostic impact of different strategies used to detect chromosome 13 deletion (Delta13) remains controversial. To address this, we compared conventional cytogenetics and interphase fluorescence in situ hybridization (iFISH) in a large multicenter study (n=794). The ability to obtain abnormal metaphases was associated with a poor prognosis, which was worse if Delta13, p53 deletion or t(4;14) was present, but only Delta13 remained significant on multivariate analysis. Patients with Delta13, by either cytogenetics or iFISH, had a poor prognosis. However, when cases with Delta13 detectable by both cytogenetics and iFISH were separated from those detected by iFISH only, the poor prognosis of iFISH-detectable Delta13 disappeared; their outcome matched that of patients with no detectable Delta13 (P=0.115). Addition of ploidy status to iFISH-Delta13 did not affect the prognostic value of the test. Indeed both cytogenetics and iFISH Delta13 divided both hyperdiploidy and nonhyperdiploidy into two groups with similar prognoses, indicating that the poor prognosis of ploidy is entirely due to its association with Delta13. We conclude that Delta13 detected by metaphase analysis is a critical prognostic factor in myeloma. Absence of Delta13, even in those patients yielding only normal or no metaphases, is associated with a relatively good prognosis.

Treatment strategy and long-term results in paediatric patients treated in consecutive UK AML trials

Between 1988 and 2002, 758 children with acute myeloid leukaemia (AML) were treated on Medical Research Council (MRC) AML 10 and AML 12. MRC AML 10 tested the role of bone marrow transplantation following four blocks of intensive chemotherapy and found that while both allogeneic bone marrow transplant (allo-BMT) and autologous bone marrow transplant (A-BMT) significantly reduced the relapse risk (RR), this did not translate into a significant improvement in overall survival (OS). A risk group stratification based on cytogenetics and response to the first course of chemotherapy derived from MRC AML 10 was used to deliver risk-directed therapy in MRC AML 12. Allo-BMT was limited to standard and poor risk patients and A-BMT was not employed. Instead, the benefit of an additional block of treatment was tested by randomising children to receive either four or five blocks of treatment in total. While the results of MRC AML 12 remain immature, there appears to be no survival advantage for a fifth course of treatment. The 5 year OS, disease-free survival (DFS), event-free survival (EFS) and RR in MRC AML 12 are 66, 61, 56 and 35%, respectively; at present superior to MRC AML 10, which had a 5-year OS, DFS, EFS and RR of 58, 53, 49 and 42%, respectively. MRC AML trials employ a short course of triple intrathecal chemotherapy alone for CNS-directed treatment and CNS relapse is uncommon. Improvements in supportive care have contributed to improved outcomes and the number of deaths in remission fell between trials. Anthracycline-related cardiotoxicity remains a concern and the current MRC AML 15 trial tests the feasibility of reducing anthracycline dosage without compromising outcome by comparing standard MRC anthracycline-based consolidation with high-dose ara-C. MRC studies suggest that the role of allo-BMT is limited in 1st CR and that there may be a ceiling of benefit from current or conventional chemotherapy.

Age has a profound effect on the incidence and significance of chromosome abnormalities in myeloma

A simple high throughput micro-fluorescence in situ hybridisation technique (FISH) was used to detect chromosome 13 deletions (delta13), immunoglobulin heavy chain (IgH) rearrangements, t(11;14)(q13;q32), t(4;14)(p16;q32), t(14;16)(q23;q32), p53 loss, and numerical changes of chromosomes 3, 6, 7, 9, 10, 11 and 17 in 228 cases of multiple myeloma (MM), including 33 asymptomatic/smouldering MM (SMM). The patients were not part of a clinical trial and were from 30 different hospitals. In all, 98.4% of cases were abnormal, with 43% having IgH rearrangements and 42% Delta13. The low incidence of IgH rearrangements was due to a decrease in this finding with age (P = 0.001) and the relatively high proportion of elderly patients in our study population (41% >70 years old). The incidence of specific IgH translocations was t(4;14) 11%, t(11;14) 16% and t(14;16) 3%. Univariate statistical testing showed delta13 (P = 0.002), and t(14;16) (P = 0.005) to be associated with shorter survival. This effect was exaggerated for patient's aged 70 years or under but no effect on survival was seen for those over 70 years. In younger patients t(4;14) (P = 0.044) and p53 deletion (P < 0.001) were also significant poor prognostic indicators. Multivariate analysis showed delta13 and t(14;16) to be independent prognostic variables when considered with age and clinical parameters.

Derivative chromosome 9 deletions are a significant feature of childhood Philadelphia chromosome positive acute lymphoblastic leukaemia

Deletions from the derivative chromosome 9, der(9), of the translocation, t(9;22)(q34;q11), at the site of the ABL/BCR fusion gene, have been demonstrated by fluorescence in situ hybridisation (FISH), in both Philadelphia chromosome (Ph)-positive chronic myeloid leukaemia (CML) and acute lymphoblastic leukaemia (ALL). In CML they occur in 10-15% of cases and appear to indicate a worse prognosis, whereas in ALL, the situation is unclear. This study presents the findings of dual fusion FISH used to detect such deletions in a series of 27 BCR/ ABL-positive childhood ALL patients. Metaphase FISH was essential for the accurate interpretation of interphase FISH signal patterns. Three cases (11%) had a single fusion signal, resulting from deletions of the der(9). Three other patients with variant translocations and one with an insertion, also had a single fusion, but with no evidence of deletions. Gain of a fusion in approximately one-third of patients indicated a second Ph, which appears to be a diagnostic marker of Ph-positive ALL. This study shows that the incidence of deletions from the der(9) in childhood ALL is at least as high as that reported for CML.

No prognostic effect of additional chromosomal abnormalities in children with acute lymphoblastic leukemia and 11q23 abnormalities

This study characterized the additional chromosomal abnormalities (ACA) associated with 11q23 rearrangements in 450 infants and children with acute lymphoblastic leukemia (ALL) and examined the impact of these ACA on survival. Overall, 213 (47%) cases had ACA but the incidence varied according to patient age and 11q23 subgroup. Infants and patients with t(4;11)(q21;q23) had the lowest incidence of ACA (50/182 (27%) and 57/216 (26%) respectively), whereas patients with del(11)(q23) had the highest incidence (66/93 (71%)). Del(11)(q23) abnormalities were heterogeneous and occasionally secondary to t(9;22)(q34;q11.2). Thus, patients with del(11)(q23) comprised a separate biological entity, which was clearly distinct from those with an 11q23 translocation. The most frequent specific ACA were trisomy X (n = 38), abnormal 12p (n = 32), abnormal 9p (n = 28) and del(6q) (n = 19). The presence of ACA did not change the 5 year event-free survival estimates among children (56% (95% Cl 46-65%) vs 62% (54-69%)) or infants (22% (15-29%) vs 18% (9-29%)), nor when the different 11q23 subgroups were analyzed separately. This study has conclusively demonstrated that there is no prognostic effect of secondary chromosomal changes in association with 11q23 abnormalities in childhood ALL. However, characterization of these ACA is important to determine their potential role in initiation of MLL driven leukemogenesis.

Secondary cytogenetic aberrations in childhood Philadelphia chromosome positive acute lymphoblastic leukemia are nonrandom and may be associated with outcome

Additional chromosomal aberrations occur frequently in Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL) of childhood. The treatment outcome of these patients is heterogeneous. This study assessed whether such clinical heterogeneity could be partially explained by the presence and characteristics of additional chromosomal abnormalities. Cytogenetic descriptions were available for 249 of 326 children with Ph+ ALL, diagnosed and treated by 10 different study groups/large single institutions from 1986 to 1996. Secondary aberrations were present in 61% of the cases. Chromosomes 9, 22, 7, 14, and 8 were most frequently abnormal. Most (93%) karyotypes were unbalanced. Three main cytogenetic subgroups were identified: no secondary aberrations, gain of a second Ph and/or >50 chromosomes, or loss of chromosome 7, 7p, and/or 9p, while other secondary aberrations were grouped as combinations of gain and loss or others. Of the three main cytogenetic subgroups, the loss group had the worst event-free survival (P=0.124) and disease-free survival (P=0.013). However, statistical significance was not maintained when adjusted for other prognostic factors and treatment. Karyotypic analysis is valuable in subsets of patients identified by molecular screening, to assess the role of additional chromosomal abnormalities and their correlation with clinical heterogeneity, with possible therapeutic implications.

Prenatal origin of hyperdiploid acute lymphoblastic leukemia in identical twins

Studies in identical twins and with neonatal blood spots (Guthrie cards) have backtracked the origin of childhood acute leukemia and their associated chromosomal translocations to before birth. High hyperdiploidy is the most common genetic abnormality in childhood acute lymphoblastic leukemia (ALL). Evidence for an in utero initiation of this important genetic event in ALL is available from blood spots but remains limited. Twin children with hyperdiploid ALL have not hitherto been reported. We describe a pair of 2-year-old monozygotic twins with concordant B-cell precursor ALL and hyperdiploid karyotypes. One twin's leukemic cells had two rearranged TCRD alleles and one of these was a clonotypic Vdelta2-Ddelta3 sequence shared with leukemic cells of the other twin. The twins' leukemic cells had several different IGH V(H)-J(H) rearrangements but shared two common D(H)-J(H) 'stem' sequences. We conclude that ALL in these twins is likely to have originated prenatally in one fetus before spreading to the other via intraplacental anastomoses. It is likely that one or more additional postnatal genetic events was required for overt leukemogenesis.

Clinical heterogeneity in childhood acute lymphoblastic leukemia with 11q23 rearrangements

To assess the clinical heterogeneity among patients with acute lymphoblastic leukemia (ALL) and various 11q23 abnormalities, we analyzed data on 497 infants, children and young adults treated between 1983 and 1995 by 11 cooperative groups and single institutions. The substantial sample size allowed separate analyses according to age younger or older than 12 months for the various cytogenetic subsets. Infants with t(4;11) ALL had an especially dismal prognosis when their disease was characterized by a poor early response to prednisone (P=0.0005 for overall comparison; 5-year event-free survival (EFS), 0 vs 23+/-+/-12% s.e. for those with good response), or age less than 3 months (P=0.0003, 5-year EFS, 5+/-+/-5% vs 23.4+/-+/-4% for those over 3 months). A poor prednisone response also appeared to confer a worse outcome for older children with t(4;11) ALL. Hematopoietic stem cell transplantation failed to improve outcome in either age group. Among patients with t(11;19) ALL, those with a T-lineage immunophenotype, who were all over 1 year of age, had a better outcome than patients over 1 year of age with B-lineage ALL (overall comparison, P=0.065; 5-year EFS, 88+/-+/-13 vs 46+/-14%). In the heterogeneous subgroup with del(11)(q23), National Cancer Institute-Rome risk criteria based on age and leukocyte count had prognostic significance (P=0.04 for overall comparison; 5-year EFS, 64+/-+/-8% (high risk) vs 83+/-+/-6% (standard risk)). This study illustrates the marked clinical heterogeneity among and within subgroups of infants or older children with ALL and specific 11q23 abnormalities, and identifies patients at particularly high risk of failure who may benefit from innovative therapy.

Amplification of AML1 on a duplicated chromosome 21 in acute lymphoblastic leukemia: a study of 20 cases

This study identifies multiple copies of the AML1 gene on a duplicated chromosome 21, dup(21), as a recurrent abnormality in acute lymphoblastic leukemia (ALL). Clusters of AML1 signals were visible at interphase by fluorescence in situ hybridization (FISH). In metaphase, they appeared tandemly duplicated on marker chromosomes of five distinct morphological types: large or small acrocentrics, metacentrics, submetacentrics or rings. The markers comprised only chromosome 21 material. Karyotypes were near-diploid and, besides dup(21), no other established chromosomal changes were observed. A total of 20 patients, 1.5 and <0.5% among consecutive series of childhood and adult ALL respectively, showed this phenomenon. Their median age was 9 years, white cell counts were low and all had a pre-B/common immunophenotype. Although this series is not the first report of this abnormality, it is the largest, permitting a detailed description of the variety of morphological forms that duplicated chromosome 21 can assume.

Treatment of infants with lymphoblastic leukaemia: results of the UK Infant Protocols 1987-1999

One hundred and twenty-six infants with acute lymphoblastic leukaemia (ALL) were treated on two consecutive protocols, Infant 87 (n = 40) and Infant 92 (n = 86), in an attempt to improve the poor prognosis of this disease. Both included intensive induction and consolidation with intrathecal and high-dose systemic therapy for central nervous system (CNS) protection. Intensification therapy was modified and high-dose chemotherapy with bone marrow transplantation in first remission was permitted in Infant 92. Four-year event-free survival was superior in Infant 92 (33%; 95% CI 23-44%) compared with Infant 87 (22.5%; 95% CI 12-37%) (P = 0.04) and survival at 4 years was also superior, 46% (95% CI 35-57%) c.f. 32.5% (95% CI 20-48%) (P = 0.01), largely as a result of a significant reduction in remission deaths. Twelve patients in Infant 92 underwent bone marrow transplantation (BMT) in first remission, but their survival was no better than that of patients receiving chemotherapy. Multivariate analysis of prognostic factors showed the adverse influence of younger age, CNS involvement at diagnosis and a high initial leucocyte count, but not of CD10 expression. Cytogenetic analysis, available in 93% of patients in Infant 92, showed that 67% had chromosomal rearrangements involving 11q23 of which 39% had the translocation t(4;11) (q21;q23). There was no significant difference in event-free survival between cytogenetic subgroups, although no children under 6 months of age with 11q23 abnormalities, other than the t(4;11), survived. In conclusion, infants with lymphoblastic leukaemia remain a high-risk group, but it is unclear whether their adverse prognosis can be attributed to unfavourable cytogenetics alone. The role of high-dose therapy and BMT in first remission remains uncertain.

Clinical features, cytogenetics and outcome in acute lymphoblastic and myeloid leukaemia of infancy: report from the MRC Childhood Leukaemia working party

The clinical features, cytogenetics and response to treatment have been examined in 180 infants (aged <1 year) with acute leukaemia; 118 with acute lymphoblastic leukaemia (ALL) and 62 with acute myeloid leukaemia (AML). Comparison of clinical features showed no difference in age or sex distribution between infants with ALL and AML but infants with ALL tended to have higher leucocyte counts at presentation. Cytogenetic abnormalities involving 11q23 were found in 66% of ALL and 35% of AML cases, the commonest, t(4;11) being found only in ALL. The other recognised 11q23 translocations were found in both types of leukaemia. Few patients had the common cytogenetic abnormalities associated with ALL in older children and few with AML had good risk abnormalities. Four year event-free survival 60% cf 30% (P = 0.001) and survival 65% cf 41% (P = 0.007) were significantly better in AML than ALL. These results were due to a lower risk of relapse 27% cf 62% at four years. Superior event-free survival was also seen in the subgroup of patients with 11q23 abnormalities and AML (55% cf 23%). The reasons for superior response in AML are unknown but may be related to the intensity of treatment, lineage of the leukaemia or other as yet unidentified factors.

ETV6/AML1 fusion by FISH in adult acute lymphoblastic leukemia

Dual-color interphase fluorescence in situ hybridization (FISH) with ETV6 and AML1 probes was used for the first time on a series of 159 adult patients with acute lymphoblastic leukemia (ALL), for detection of the t(12;21)(p13;q22) translocation. Seven patients (4.4%) were found, with 50-100% of positive cells, of whom one of two tested, proved negative for the fusion product by RT-PCR. Two of them, aged 43 and 50 years, are the oldest patients so far confirmed to have the translocation. Three who relapsed at 10, 11 and 24 months, suggest that adults may not enjoy the good short-term prognosis reported for t(12;21)-positive children. Thirty-one-negative cases had signal numbers differing from the two expected for each gene. In 15 cases these results were consistent with the karyotype. In nine cases with uninformative cytogenetics, the numbers were consistent with those for centromeres and indicated a hidden aneuploidy. Loss of ETV6 genes in two cases and AML1 amplification in three others were not suspected from the cytogenetics. In conclusion, FISH proved to be reliable in defining ETV6/AML1 positivity in this group of patients as well as providing valuable insights into negative cases.

Immunomodulation as a treatment strategy for genital herpes: review of the evidence

In this review, we discuss the ongoing development of a new treatment option for genital herpes (GH), the disease caused by herpes simplex virus (HSV) types I and II. Following infection, the virus establishes a latent infection in peripheral neurons, which periodically activates to cause recurrent skin lesions or asymptomatic shedding in the anogenital area. A new class of drugs, the immune response modifiers (IRMs), modulates the immune system against viral infection. This approach is currently being tested as a treatment for GH. We first review the effectiveness of treatment of other viral diseases with imiquimod, the first IRM to be licensed (Aldara, imiquimod 5% cream), and one used for the treatment of external anogenital warts. We then focus on resiquimod, an analog of imiquimod, which shows early promise as a new treatment option for GH. The evidence from in vitro and in vivo studies, in particular the guinea pig model of GH, describing the effectiveness and mode of action of this novel immunopharmacological agent is presented. Resiquimod stimulates specific cells of the innate immune system (including monocytes/macrophages, dendritic cells (DC) and B lymphocytes) to produce cytokines (in particular IFN-alpha, IL-12, TNF-alpha and IFN-gamma) that initiate and drive the development of the Th1 acquired immune response against HSV-infected cells. Recent results from clinical trials and in vivo studies in animal models are consistent with the hypothesis that the development of HSV-specific cell-mediated immunity may prove to be the key in providing a long-lasting protection against GH recurrences.

Severe intrauterine herpes simplex disease with placentitis in a newborn of a mother with recurrent genital infection at delivery

We present a case of fatal herpes simplex type 2 (HSV-2) in a premature infant born to a mother diagnosed with recurrent HSV-2, based on history and HSV serology results. It was clinically evident at delivery, and subsequently confirmed by laboratory studies that the infant was infected before delivery. There was histopathologic evidence of placentitis and chorioamnionitis upon examination of the placenta and fetal membranes. This case illustrates a relatively uncommon complication of recurrent genital herpes at delivery--intrauterine transmission to the fetus from a primary episode during pregnancy.

Microbiology of acute otitis media recently treated with aminopenicillins

INTRODUCTION

Sparse recent data are available in the United States regarding the pathogens of acute otitis media (AOM) most likely to be recovered from children recently treated with the two most frequently prescribed antibiotics, amoxicillin or amoxicillin/clavulanate (AMC).

METHODS

Of the 704 rural Kentucky children with culture-positive AOM who underwent a single tympanocentesis or culture of otorrhea between 1992 and 1998, 96 pathogens were recovered from 90 children during therapy or within 7 days posttherapy with an aminopenicillin. Identification and susceptibility testing of AOM pathogens were performed by routine National Committee for Clinical Laboratory Standards methods.

RESULTS

Pathogens recovered from children with AOM recently treated (0 to 7 days) with amoxicillin (n = 38) and AMC (n = 58), respectively, were as follows: Haemophilus influenzae (beta-lactamase-negative), 16 and 29%; H. influenzae (beta-lactamase-positive), 11 and 22%; penicillin-susceptible Streptococcus pneumoniae, 26 and 12%; intermediately penicillin-nonsusceptible S. pneumoniae (PNSP), 20 and 10%; resistant PNSP 13 and 17%; Moraxella catarrhalis (beta-lactamase-positive), 13 and 7%; and Streptococcus pyogenes, 3 and 2%. H. influenzae was also isolated from 8 (75%) of 12 children treated with high dose AMC ( approximately 80 mg/kg/day amoxicillin component). Significantly fewer children recently treated with amoxicillin were otitis-prone than those given AMC (24% vs. 74%, P < 0.0001).

CONCLUSIONS

The predominant pathogen recovered from children with AOM recently treated with amoxicillin was S. pneumoniae (59%) rather than beta-lactamase-producing organisms (24%). H. influenzae was the predominant (51%) pathogen, rather than PNSP (27%), recovered from children recently treated with AMC.

Restricted use of antibiotic prophylaxis for recurrent acute otitis media in the era of penicillin non-susceptible Streptococcus pneumoniae

OBJECTIVE/INTERVENTION: To compare the annual rates of acute otitis media (AOM) episodes, antibiotic days, and ventilating tube insertion during the first 3 years of life before and after a practice change to restrict use of antibiotic chemoprophylaxis for recurrent AOM.

METHODS SETTING

The sole pediatric private practice in a rural Kentucky community.

PATIENTS

Population-based sample of all children born consecutively in two different 13 month intervals. Cohort 1 (n=251) was born before and Cohort 2 (n=274) was born after restricted use of chemoprophylaxis and documented emergence of widespread penicillin non-susceptible Streptococcus pneumoniae (PNSP).

DESIGN

Retrospective case cohort comparison.

MAIN OUTCOME MEASURES

Suppurative AOM diagnosed by validated experienced otoscopists using stringent tympanic membrane criteria.

RESULTS

Children were mostly white with the majority (50-65%) enrolled in daycare during each year. The first episode of AOM was experienced by 6 and 12 months of age in 64 and 86%, respectively. Rates of children with recurrent AOM in Cohorts 1 and 2 were 28 and 31% in Year 1, 17 and 23% in Year 2, and 7 and 10% in Year 3, respectively. Rates of new onset AOM and persistent AOM episodes were similar between cohorts in the first 2 years. Number of days of antibiotic prophylaxis were reduced from 11.2 to 3.4 days in Year 1, from 11.9 to 2.6 days in Year 2, and from 6.9 to 0.7 days in Year 3, respectively (P<0.0001 for each year). Total antibiotic days for Years 1, 2 and 3 were reduced commensurately with prophylactic days from 61.7 to 55.5 days (nonsignificant), from 56.3 to 45.8 days (P=0.047), and from 38.7 to 25.7 days (P<0.0001), respectively. For each year a non-significant trend for increased ventilating tube placement from Cohort 1 to Cohort 2, respectively, was observed, 2 versus 2.2%, 4 versus 5.8%, and 0.8 versus 2.6%. Daycare attendance and white race were consistently significant risk factors for AOM and recurrent AOM.

CONCLUSIONS

In the era of PNSP, restricted use of antibiotic chemoprophylaxis for recurrent AOM was not associated with significantly increased rates of new onset AOM episodes or tube placement in the first 24 months of life. Total antibiotic days were also significantly reduced in Cohort 2 during Years 2 and 3.

Heterogeneity of VH-JH gene rearrangement patterns: an insight into the biology of B cell precursor ALL

Oligoclonal B cell proliferation, as defined by the presence of more than one leukemic clone, has been detected in approximately 20% to 30% of patients with acute lymphoblastic leukemia (ALL) using PCR or Southern blotting. An accurate assessment of these populations is required to avoid false negative measurements of minimal residual disease (MRD) in follow-up bone marrow (BM) samples of ALL patients. In this study, we analysed 29 ALL patients with two or more immunoglobulin heavy (IGH) chain gene rearrangements in the presentation samples using IGH fingerprinting PCR and sequence analysis. Thirty-nine (51%) of 76 sequences (from 15 patients), shared no VNDNJ homology (ie different CDR3 regions). In the remaining 14 patients, at least two related VH sequences were identified in each patient (identical DNJ sequences). Numerical abnormalities of chromosome 14 was detected in 10 patients. Eight patients were analysed at presentation and relapse. In four of them, expansion of a minor presentation-clone was detected at relapse while the major presentation clone disappeared, confirming 'subclonal evolution'. Finally, in our cohort of patients, the presence of related or unrelated IGH clones did not influence overall survival.

Acute lymphoblastic leukaemia

In acute lymphoblastic leukaemia (ALL) the karyotype provides important prognostic information which is beginning to have an impact on treatment. The most significant structural chromosomal changes include: the poor-risk abnormalities; t(9;22)(q34;q11), giving rise to the BCR/ABL fusion and rearrangements of the MLL gene; abnormalities previously designated as poor-risk; t(1;19)(q23;p13), producing the E2A/PBX1 and rearrangements of MYC with the immunoglobulin genes; and the probable good risk translocation t(12;21)(p13;q22), which results in the ETV6/AML1 fusion. These abnormalities occur most frequently in B-lineage leukaemias, while rearrangements of the T cell receptor genes are associated with T-lineage ALL. Abnormalities of the short arm of chromosome 9, in particular homozygous deletions involving the tumour suppressor gene (TSG) p16(INK4A), are associated with a poor outcome. Numerical chromosomal abnormalities are of particular importance in relation to prognosis. High hyperdiploidy (51-65 chromosomes) is associated with a good risk, whereas the outlook for patients with near haploidy (23-29 chromosomes) is extremely poor. In view of the introduction of risk-adjusted therapy into the UK childhood ALL treatment trials, an interphase FISH screening programme has been developed to reveal chromosomal abnormalities with prognostic significance in childhood ALL. Novel techniques in molecular cytogenetics are identifying new, cryptic abnormalities in small groups of patients which may lead to further improvements in future treatment protocols.

The predictive value of hierarchical cytogenetic classification in older adults with acute myeloid leukemia (AML): analysis of 1065 patients entered into the United Kingdom Medical Research Council AML11 trial

Acute myeloid leukemia (AML) in older adults carries a poor prognosis, and the optimum treatment remains to be determined. In younger patients, treatment stratification is frequently based upon diagnostic karyotype, which was the most important prognostic factor in the UK Medical Research Council (MRC) AML10 trial. Considered here is whether karyotype is also predictive in older adults; this is done by studying 1065 cases from MRC AML11 (median age, 66 years). Three prognostic groups were distinguished on the basis of response to induction therapy and overall survival (OS). Those with t(15;17), t(8;21), or inv(16) composed the favorable risk group. Overall, these abnormalities predicted a superior complete remission (CR) rate (72%), reflecting relatively low levels of resistant disease (RD) (8%), and lower relapse risk (RR) (56%) associated with superior OS (34% at 5 years). Normal karyotype (CR, 63%; RD, 17%; RR, 78%; OS, 15%) and other noncomplex abnormalities (CR, 53%; RD, 32%; RR, 85%; OS, 10%) composed the intermediate group; while complex karyotype predicted an extremely poor prognosis (CR, 26%; RD, 56%; RR, 91%; OS, 2%). Combining MRC AML10 and AML11 (n = 2677) revealed that the most favorable changes were rarer in older patients (younger than 55 years, 24%; 55 years or older, 7%), while complex abnormalities were more common (6% vs 13%). This study suggests that hierarchical cytogenetic classification identifies biologically distinct subsets of AML that are represented in all age groups. Furthermore, it highlights the importance of karyotype as a critical independent determinant of outcome in older patients with AML, providing a potential framework for stratified treatment approaches.

Molecular tracking of leukemogenesis in a triplet pregnancy

The occurrence of childhood acute lymphoblastic leukemia (ALL) in 2 of 3 triplets provided a unique opportunity for the investigation of leukemogenesis and the natural history of ALL. The 2 leukemic triplets were monozygotic twins and shared an identical, acquired TEL-AML1 genomic fusion sequence indicative of a single-cell origin in utero in one fetus followed by dissemination of clonal progeny to the comonozygotic twin by intraplacental transfer. In accord with this interpretation, clonotypic TEL-AML1 fusion sequences could be amplified from the archived neonatal blood spots of the leukemic twins. The blood spot of the third, healthy, dizygotic triplet was also fusion gene positive in a single segment, though at age 3 years, his blood was found negative by sensitive polymerase chain reaction (PCR) screening for the genomic sequence and by reverse transcription-PCR. Leukemic cells in both twins had, in addition to TEL-AML1 fusion, a deletion of the normal, nonrearranged TEL allele. However, this genetic change was found by fluorescence in situ hybridization to be subclonal in both twins. Furthermore, mapping of the genomic boundaries of TEL deletions using microsatellite markers indicated that they were individually distinct in the twins and therefore must have arisen as independent and secondary events, probably after birth. These data support a multihit temporal model for the pathogenesis of the common form of childhood leukemia.