The Sox4/Tcf7l1 axis promotes progression of BCR-ABL-positive acute lymphoblastic leukemia.

The transcription factor Sox4 plays an indispensable role in the development of early progenitor B cells from hematopoietic stem cells. However, its role in B-cell acute lymphoblastic leukemia, a malignant counterpart of normal progenitor B cells, is not fully understood. Here we show that SOX4 is highly expressed in human acute lymphoblastic leukemia cells. To systematically study the function of Sox4 in acute lymphoblastic leukemia, we established a genetically defined mouse leukemia model by transforming progenitor B cells carrying a floxed Sox4 allele and inducing deletion of the allele by the self-excising Cre recombinase. This model allowed us to work with two groups of leukemic cells that had either one copy or both copies of Sox4 deleted. We found that depletion of Sox4 in transformed cells in vitro reduced cell growth in vitro and the progression of leukemia in vivo. Moreover, depletion of Sox4 in leukemic cells in vivo prolonged the survival of the mice, suggesting that it could be a potential target in acute lymphoblastic leukemia therapy. Our microarray and bioChIP studies revealed that Tcf7l1 was the key gene directly regulated by Sox4. Knockdown of Tcf7l1 reduced cell proliferation, just as did knockout of Sox4, and ectopic expression of Tcf7l1 could reverse the effect of Sox4 knockout on cell proliferation. These data suggest that Sox4 and Tcf7l1 form a functional axis that promotes the progression of BCR-ABL-positive acute lymphoblastic leukemia.

Male-to-female sex ratios of abnormalities detected by fluorescence in situ hybridization in a population of chronic lymphocytic leukemia patients.

Distorted sex ratios occur in hematologic disorders. For example, chronic lymphocytic leukemia (CLL) displays disproportionate sex ratios with a large male excess. However, the underlying genetics for these disparities are poorly understood, and gender differences for specific cytogenetic abnormalities have not been carefully investigated. We sought to provide an initial characterization of gender representation in genetic abnormalities in CLL by using fluorescence in situ hybridization (FISH). We confirm the well known skewed male-tofemale (M/F sex ratio) of ~1.5 in our CLL study population, but also determine the genotypic M/F sex ratio values corresponding to specific FISH DNA probes. Genetic changes in CLL detectable by four FISH probes were statistically compared with respect to gender. Initial FISH evaluations of 4698 CLL patients were retrospectively examined and new findings of the genotypic M/F sex ratios for these probes are reported. This study represents the largest CLL survey conducted in the United States using FISH probes. The CLL database demonstrated that FISH abnormalities (trisomy 12, 13q14.3 deletion and 17p13.1 deletion) probes had skewed M/F ratios of ~1.5. Also, by statistical analysis it was shown that ATM gene loss (11q22.3q23.1 deletion) solely or with other abnormalities was considerably higher in males with an M/F ratio of 2.5 and significantly different from M/F ratios of 1.0 or 1.5. We hypothesize that interactions involving these autosomal abnormalities (trisomy 12, and deletions of 11q22.3, 13q14.3, and 17p13.1), and the sex chromosomes may provide the genetic basis for the altered phenotypic M/F ratio in CLL.

The lung permeability index: a feasible measurement of pulmonary capillary permeability.

BACKGROUND: We performed this study to determine the pulmonary capillary permeability (PCP) measuring radiolabeled human serum albumin leakage into the lung. The objective was to use PCP to differentiate between cardiogenic and non-cardiogenic pulmonary edema etiologies. METHODS: We conducted this study in 10 patients admitted to the intensive care unit who had recently developed bilateral pulmonary infiltrates and required hemodynamic monitoring. In these patients we determined the association among the lung permeability index, cardiac output, pulmonary capillary wedge pressure, myocardial performance index, and the protein content of the bronchoalveolar lavage as expressed by bronchoalveolar lavage (BAL) total protein and BAL-to-serum protein ratio. Twenty mCi of technetium-labeled albumin was injected and measure in the heart and the lung at 10 and 180 min post-injection. Lung and heart uptake ratios as well as the lung permeability index were calculated. RESULTS: We found a good correlation between the lung permeability index and both the myocardial performance index (cardiac output/pulmonary capillary wedge pressure) and the total protein content of the bronchoalveolar lavage fluid. CONCLUSION: The lung permeability index is a feasible, noninvasive estimation of the pulmonary capillary permeability.

inv(16)(p13q22) in chronic myelogenous leukemia in blast phase: a clinicopathologic, cytogenetic, and molecular study of five cases.

Blast phase (BP) in chronic myelogenous leukemia (CML) frequently is accompanied by cytogenetic abnormalities in addition to t(9;22)(q34;q11.2). We describe 5 patients with CML in blast phase (CML-BP) in which t(9;22) and inv(16)(p13q22) were identified by conventional cytogenetics, with confirmation of BCR-ABL and CBFss-MYH11 by fluorescence in situ hybridization. The morphologic findings at the time of BP resembled de novo acute myeloid leukemia (AML) carrying inv(16)(p13q22), with abnormal eosinophils in the bone marrow and monocytosis in the peripheral blood in all cases. In 1 patient, inv(16)(p13q22) and abnormal eosinophils were detected in the bone marrow 2 months before CML-BP. The clinical course of these patients was similar to patients with CML-BP without evidence of inv(16)(p13q22). These cases illustrate that inv(16)(p13q22) is a form of cytogenetic evolution that rarely occurs in patients with CML at the time of BP. In this setting, unlike de novo AML, inv(16)(p13q22) in CML-BP is not associated with a favorable prognosis.

Morphologic, cytogenetic, and molecular abnormalities in therapy-related acute promyelocytic leukemia.

We describe 17 cases of therapy-related acute promyelocytic leukemia (tAPL). Treatment for the initial neoplasms (mostly carcinomas and non-Hodgkin lymphomas) included radiation and chemotherapy in 11 patients, radiation in 3, and chemotherapy in 3. The interval between the initial neoplasm and tAPL ranged from 17 to 166 months (median, 40 months). Morphologically, all 13 cases with available bone marrow aspirate smears showed tAPL. Dyserythropoiesis or dysmegakaryopoiesis was identified in 11 cases. In 2 cases, too few nonneoplastic cells and, in all cases, too few maturing granulocytes were present to assess for dysplasia. Conventional cytogenetics or fluorescence in situ hybridization (FISH) showed the t(15;17)(q22;q21) in all cases; 6 as a sole abnormality, 9 with additional abnormalities, and 2 assessed only by FISH. Reverse transcription-polymerase chain reaction (PCR) studies showed PML/RARa in 13 cases (8 short form, 5 long form). Mutations of the flt3 gene were detected by PCR in 5 (42%) of 12 cases. We conclude that dysplastic features, secondary cytogenetic abnormalities, and flt3 mutations are common in tAPL.

Myelodysplasia and acute myeloid leukemia following therapy for indolent lymphoma with fludarabine, mitoxantrone, and dexamethasone (FND) plus rituximab and interferon alpha.

Treatment-related myelodysplasia (t-MDS) occurs less frequently with the nucleoside analogs than with DNA-damaging agents such as alkylators or topoisomerase II inhibitors. In a chemoimmunotherapy trial conducted between 1997 and 2003 in patients with stage IV indolent lymphoma, 202 patients were treated and 8 have developed MDS between 1 and 5 years after therapy, including 4 who received only fludarabine, mitoxantrone, and dexamethasone (FND) for 6 to 8 courses, with or without rituximab, followed by interferon alpha (IFN-alpha). Complex cytogenetic abnormalities were present in all patients. Abnormalities of chromosome 7 were present in 6 of the 8 patients, 3 of whom received only FND +/- rituximab and IFN-alpha. The abnormalities of chromosome 7 were monosomy 7 in 4 patients (1 of which had add 7p in the remaining chromosome); 1 del 7q; and 1 der 7. MDS with features classically associated with DNA-damaging agents can occur following therapy with FND, with or without rituximab, and IFN-alpha.

The value of fluorescence in situ hybridization in the diagnosis and prognosis of chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia. Prognosis is related to clinical staging and cytogenetic findings. Conventional cytogenetic analysis of CLL reveals abnormalities in approximately one third of patients. Fluorescence in situ hybridization (FISH) is analytically more sensitive than conventional cytogenetics for specific chromosomal abnormalities. To evaluate the usefulness of FISH in CLL, a study of 100 CLL patients comparing conventional cytogenetics and a commercially available multiprobe FISH kit was undertaken. One hundred consecutive CLL patients (67 males, 33 females) were studied. The male-female patient ratio was approximately 2.0 to 1. Twenty-eight percent (28/98) of patients had abnormal karyotypes by conventional cytogenetics (one patient had no specimen for conventional cytogenetics and one had an unanalyzable karyotype), and of those 19/100 (19%) had more than one chromosomal abnormality. Sixty-four percent (64/100) of the patients were positive for at least one abnormality by the FISH probes used. The following abnormalities were noted with FISH: 11q22 ATM, 23/100 (23%); trisomy 12, 11/100 (11%); 13q14.3, 40/100 (40%); 13q34.3, 4/100 (4%); 17p13.1, 12/100 (12%). Conventional karyotypes revealed 2 patients with abnormalities of chromosome 6 (which FISH did not address); 11 with abnormalities of 11 or 11q; 6 with trisomy 12; and 4 with abnormalities of 17. Aberrations of 11q and 17p are reported to have a poor prognosis in CLL. FISH can identify abnormalities missed with conventional cytogenetics and is helpful in diagnosis, prognosis, and evaluation of therapy for CLL. Additional chromosomal changes are identified with conventional cytogenetics that are not addressed by the multiprobe FISH kit.

The utility of interphase fluorescence in situ hybridization for the detection of the translocation t(11;14)(q13;q32) in the diagnosis of mantle cell lymphoma on fine-needle aspiration specimens.

BACKGROUND: Mantle cell lymphoma can be difficult to differentiate cytologically from other small cell non-Hodgkin lymphomas. Nevertheless, the distinction is important, because mantle cell lymphoma is more aggressive than other small cell non-Hodgkin lymphomas. The purpose of this study was to determine whether fluorescence in situ hybridization (FISH) is helpful in diagnosing mantle cell lymphoma on fine-needle aspiration (FNA) specimens by detecting the t(11;14)(q13;q32) translocation that is characteristic of this tumor. METHODS: Fifty-five lymph node FNA specimens from 53 patients were analyzed using FISH. A 2-color FISH assay that employed probes at the 14q32 (immunoglobulin H) and 11q13 (dual-colored, directly labeled cyclin D1) loci was used. The number of single-fusion and double-fusion signals in 200 cells was counted. If > or = 14% single-fusion signals or > or = 1.5% double-fusion signals or both were present, then the sample was considered FISH positive. The findings were correlated with the cytologic, histologic, and immunophenotypic findings in each specimen. RESULTS: Of the 55 cytology specimens, 17 were mantle cell lymphomas, and 38 were nonmantle cell lymphomas, including 16 small lymphocytic lymphomas (9 of 16 in an accelerated phase), 5 large cell lymphomas, 5 follicular lymphomas, 7 transformed large cell lymphomas (Richter syndrome), 3 atypical lymphoid proliferations, and 2 low-grade B-cell lymphomas. All 17 mantle cell lymphomas were positive by FISH. In addition, there were six small lymphocytic lymphomas (two in accelerated phase), one transformed large cell lymphoma, and one large cell lymphoma of follicular origin positive by FISH. The mean number of single-fusion and double-fusion signals, respectively, was 36 and 33 in mantle cell lymphoma specimens and 19 and 3 in positive nonmantle cell lymphoma specimens. CONCLUSIONS: The detection of the t(11;14)(q13;q32) translocation by FISH analysis was helpful in diagnosing mantle cell lymphoma on FNA specimens. Double-fusion signals were more specific for mantle cell lymphoma than single-fusion signals. In rare instances, other non-Hodgkin lymphomas also showed increased numbers of single-fusion signals that were not necessarily indicative of the t(11;14)(q13;q32) translocation. Therefore, in an initial diagnosis of mantle cell lymphoma, significant numbers of double-fusion FISH signals should be identified and interpreted in conjunction with the cytologic and immunologic studies.

Imatinib mesylate therapy may overcome the poor prognostic significance of deletions of derivative chromosome 9 in patients with chronic myelogenous leukemia.

Deletions of derivative chromosome 9 [der(9)] can be identified by fluorescence in situ hybridization (FISH) in 10% to 15% of patients with chronic myeloid leukemia (CML). Patients with der(9) deletions have been reported to have an adverse outcome when treated with chemotherapy, interferon, and possibly imatinib mesylate. We investigated the frequency and prognostic significance of der(9) deletions among 352 patients with CML treated with imatinib mesylate at our institution, in whom a deletion status of der(9) was determined. Thirty-three patients (9%; 95% CI 0.07, 0.13) (30 in chronic phase, 3 in accelerated phase) had der(9) deletions. The rates of major (82% vs 79%, P = 0.82) and complete cytogenetic response (76% vs 66%, P = .33) with imatinib mesylate therapy were similar in patients with and without der(9) deletions, respectively. After a median follow-up of 28 months, there was no difference in overall survival (P = .30) or response duration (P = .49) in patients with and without deletions. In a multivariate analysis, der(9) deletions had no significant impact on response, survival, or response duration. We conclude that treatment with imatinib mesylate overcomes the adverse prognostic significance of der(9) deletions in patients with CML.

Acute myeloid leukemia with t(6;9)(p23;q34) is associated with dysplasia and a high frequency of flt3 gene mutations.

We report 12 cases of t(6;9)(p23;q34)-positive acute myeloid leukemia (AML), all classified using the criteria of the World Health Organization classification. There were 10 women and 2 men with a median age of 51 years (range, 20-76 years). Dysplasia was present in all cases (9 previously untreated), and basophilia was present in 6 (50%). Immunophenotypic studies showed that the blasts were positive for CD9, CD13, CD33, CD38, CD117, and HLA-DR in all cases assessed. CD34 was positive in 11 (92%) of 12, and terminal deoxynucleotidyl transferase was positive in 7 (64%) of 11 cases. The t(6;9) was the only cytogenetic abnormality detected in 7 cases (58%), and 5 cases had additional chromosomal abnormalities. Of 8 cases assessed, 7 (88%) had flt3 gene mutations. We conclude that t(6;9)-positive AML cases have distinctive morphologic features, an immunophenotype suggesting origin from an early hematopoietic progenitor cell, and a high frequency of flt3 gene mutations.

Feasibility and utility of using chromosomal aneusomy to further define the cytologic categories in nipple aspirate fluid specimens: a preliminary study.

BACKGROUND: There is renewed interest in using the cytologic changes in the epithelial cells obtained from specimens such as nipple aspiration fluid (NAF) and ductal lavage for risk stratification of women at increased risk for developing breast carcinoma. METHODS: Molecular tests such as fluorescence in situ hybridization (FISH) have the potential to be used as adjuncts to conventional cytology for more accurately categorizing cells in these types of specimens. The current study investigated the feasibility and utility of FISH analysis of aneusomy in chromosomes 1, 8, 11 and 17 as an adjunct to conventional cytology in the classification of NAF specimens. RESULTS: The authors found chromosomal aneusomy for at least one chromosome in all three malignant and both markedly atypical cases. Of the five cases classified as being mildy atypical on cytology, four were disomic, and only one showed aneusomy in chromosomes 8 and 11. CONCLUSIONS: The current study established the possibilities, limitations, and feasibility of using FISH in conjunction with routine cytology for a more accurate classification of ductal epithelial cells in NAF specimens. FISH-based detection of chromosomal aneusomy helped to define mild atypia, thereby aiding in the selection of the truly atypical cases for appropriate therapeutic intervention. In addition, FISH-based detection of chromosomal aneusomy can also be a valuable adjunct to conventional cytology in selected cases for confirming a benign, suspicious, or malignant diagnosis.

Determination of secondary chromosomal aberrations of chronic myelocytic leukemia.

Chronic myeloctyic leukemia (CML) is a stem cell disorder characterized by the cytogenetic abnormality of t(9;22)(q34;q11.2), which progresses from a chronic phase to an accelerated phase (AP), and/or a blast phase (BP) of myelocytic or lymphoid phenotype. This progression is frequently preceded or accompanied by recurring secondary chromosomal abnormalities (SCA) that are believed to play a role in the transformation and may also serve as valuable prognostic indicators. Failure to note such abnormalities may lead to an inappropriate clinical evaluation. We observed CML patients with AP or BP who did not show SCA by routine cytogenetic analysis. To determine the presence or absence of specific SCA in those cases, we applied fluorescence in situ hybridization (FISH) to four CML cases with pseudodiploid cytogenetics [t(9;22)(q34;11.2) as the sole abnormality] by conventional karyotyping. Bone marrow biopsies from two AP and two BP of CML patients with pseudodiploid karyotypes by conventional cytogenetics were examined by FISH for trisomy 8 and i(17q). These SCA are major secondary chromosomal changes seen in BP of CML patients. Results were considered positive if more than 2.4% of cells had +8 and >6.25% for i(17q) by FISH. Four out of four patients were positive for +8. These results indicate that FISH techniques are valuable in the determination of SCA in CML, which were t(9;22)(q34;q11.2) positive as the sole cytogenetic abnormality with standard G-banding karyotyping and can be helpful for the early diagnosis of CML progression.

t(8;21)(q22;q22) in blast phase of chronic myelogenous leukemia.

The blast phase of chronic myelogenous leukemia (CML) frequently is associated with cytogenetic evidence of clonal evolution, defined as chromosomal aberrations in addition to the t(9;22)(q34;q11.2). We identified the t(8;21)(q22;q22) and other cytogenetic abnormalities by conventional cytogenetics and fluorescence in situ hybridization in 2 patients with t(9;22)-positive CML at the time of blast phase. The t(8;21), which typically is associated with a distinct subtype of de novo acute myeloid leukemia (AML) carrying the aml1/eto fusion gene, was accompanied by increased bone marrow myeloblasts (33%) in case 1 and extramedullary myeloid sarcoma in case 2, suggesting its possible role in disease progression. In case 1, the leukemic cells in aspirate smears had salmon-colored cytoplasmic granules, and immunophenotypic studies showed that the blasts expressed CD19. These findings suggest that the pathologic features of blast phase CML with the t(8;21) resemble those of de novo AML with the t(8;21).

Results of imatinib mesylate therapy in chronic myelogenous leukaemia with variant Philadelphia chromosome.

Five to 10 per cent of patients with Philadelphia chromosome (Ph)-positive chronic myelogenous leukaemia (CML) have variant translocations involving chromosomes other than 9 and 22. We investigated the characteristics and outcome of patients with variant translocations treated with imatinib. Among 721 patients, 44 (6%) had variant translocations, involving one (n = 39) or two (n = 4) additional chromosomes. Nineteen patients (44%) were in chronic (12 previously untreated), 24 (55%) in accelerated and one (2%) in blastic phase. A major cytogenetic response was achieved in 14 (74%) patients treated in chronic phase and in 14 (58%) treated in accelerated phase. Six of 13 (46%) evaluable patients had deletion of derivative chromosome 9, and there was a trend for a lower response rate in these patients. We compared the 43 patients in chronic or accelerated phase to 678 patients with classic Ph treated with imatinib. The only significant difference in clinical characteristics was a higher frequency of accelerated phase among those with variant translocations (56%) compared with those with classic translocations (38%). No differences in outcome were evident. In a multivariate analysis, variant Ph translocations had no impact in response rate, overall survival or duration of response. We conclude that patients with variant Ph translocations have a similar prognosis to those with classic Ph translocations when treated with imatinib.

A genetically defined model for human ovarian cancer.

Disruptions of the p53, retinoblastoma (Rb), and RAS signaling pathways and activation of human telomerase reverse transcriptase (hTERT) are common in human ovarian cancer; however, their precise role in ovarian cancer development is not clear. We thus introduced the catalytic subunit of hTERT, the SV40 early genomic region, and the oncogenic alleles of human HRAS or KRAS into human ovarian surface epithelial cells and examined the phenotype and gene expression profile of those cells. Disruption of p53 and Rb pathway by SV40 early genomic region and hTERT immortalized but did not transform the cells. Introduction of HRAS(V12) or KRAS(V12) into the immortalized cells, however, allowed them to form s.c. tumors after injection into immunocompromised mice. Peritoneal injection of the transformed cells produced undifferentiated carcinoma or malignant mixed Mullerian tumor and developed ascites; the tumor cells are focally positive for CA125 and mesothelin. Gene expression profile analysis of transformed cells revealed elevated expression of several cytokines, including interleukin (IL)-1beta, IL-6, and IL-8, that are up-regulated by the nuclear factor-kappaB pathway, which is known to contribute to the tumor growth of naturally ovarian cancer cells. Incubation with antibodies to IL-1beta or IL-8 led to apoptosis in the ras-transformed cells and ovarian cancer cells but not in immortalized cells that had not been transformed. Thus, the transformed human ovarian surface epithelial cells recapitulated many features of natural ovarian cancer including a subtype of ovarian cancer histology, formation of ascites, CA125 expression, and nuclear factor-kappaB-mediated cytokine activation. These cells provide a novel model system to study human ovarian cancer.

Expression of CD2 in acute promyelocytic leukemia correlates with short form of PML-RARalpha transcripts and poorer prognosis.

We studied the immunophenotype of 100 cases of acute promyelocytic leukemia (APL) with cytogenetic evidence of t(15;17)(q22;q21), 72 hypergranular (M3) and 28 microgranular (M3v), and correlated the results with molecular and clinical features. Most neoplasms (75/100 [75%]) had a typical immunophenotype: CD13+CD33+CD34-HLA-DR-. CD64, CD2, CD34, and HLA-DR were expressed in 27% (24/88), 23% (22/94), 21% (21/100), and 9% (9/98), respectively. CD34 expression was restricted to M3v; HLA-DR and CD2 were expressed more often in M3v than in M3 (P < .001). PML-RARalpha fusion transcripts were detected by reverse transcriptase-polymerase chain reaction in all 70 patients assessed. The short form of PML-RARalpha transcripts was found more frequently in M3v (P < .002) and CD2+ APL (P < .0001) than in M3 and CD2- APL, respectively. The median follow-up was 128 weeks. CD2+ APL was associated significantly with leukocytosis (P = .004), shorter complete remission duration (P = .03), and a trend toward shorter overall survival (P = .07) than CD2- APL. Overall survival for M3v vs M3 (P = .68) and short vs long transcripts (P = .21) was not significantly different. Immunophenotyping is useful for predicting the biologic and clinical behavior of APL.

Cytogenetic findings in blastoid mantle cell lymphoma.

A subset of mantle cell lymphoma (MCL) tumors has blastoid morphology, and a number of morphologic variants of blastoid MCL have been described in the literature. In this report, we document the cytogenetic findings in 27 cases of blastoid MCL. Conventional cytogenetic analyses were performed on bone marrow aspirates involved by MCL from 27 patients. There were 14 men and 13 women with a median age of 63 years (range, 40-79 years). Diagnostic tissue biopsy and bone marrow specimens were reviewed, and cases were divided into 2 morphologic groups: classic (12 cases) and pleomorphic (15 cases), as defined in the World Health Organization classification. All tumors had an immunophenotype compatible with MCL, were positive for cyclin D1, and carried the t(11;14). Twenty-four cases had complex karyotypes with 3 or more chromosomal abnormalities in addition to the t(11;14). In classic blastoid MCL, abnormalities of chromosomes 13, 18, and 8 were most common. In pleomorphic blastoid MCL, abnormalities of chromosomes 13, 17, and 3 were most frequent. Chromosome 22 abnormalities were detected exclusively in the pleomorphic group. Tumors in which the neoplastic cells showed prominent nucleoli had a significantly higher frequency of chromosome 17 abnormalities (P = 0.03). We conclude that blastoid MCL tumors often show complex cytogenetic aberrations. Some abnormalities correlate with morphologic features, suggesting that morphologic variants of blastoid MCL may arise via different molecular pathways.

Translocation (11;16)(q23;p13) acute myelogenous leukemia and myelodysplastic syndrome.

The purpose of this study is to examine the relationship of t(11;16)(q23;p13) to the type of myeloproliferative disorder noted by hematopathology. Previously, t(11;16) has been reported in fewer than 20 patients, all with the diagnosis of therapy-related (secondary) acute myelogenous leukemia (sAML) or myelodysplastic syndrome (MDS). Putative involved genes are the MLL on 11q23 and CBP at 16p13. Data from The University of Texas M. D. Anderson Cancer Center (UTMDACC) Cytogenetics Laboratory revealed 3 patients with t(11;16) observed during the past 5 years. Two of the patients had a prior diagnosis of non-Hodgkin lymphoma (NHL) and had been treated with chemotherapy, which included cyclophosphamide. The other patient presented with de novo AML and no history of cancer or chemotherapy. Two of the 3 patients had t(11;16) as the sole cytogenetic abnormality. One patient had a t(11;16) clone that included t(9;21) and t(10;21) as additional changes. Translocation (11;16) has previously been reported only as being therapy-related. In this study, the t(11;16) was seen in 2 patients with previous lymphomas treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP). A single patient with apparently de novo AML constitutes the first reported instance of non-treatment associated t(11;16) AML.

Bone marrow purging studies in acute myelogenous leukemia using the recombinant anti-CD33 immunotoxin HuM195/rGel.

This study was designed to determine the effect of immunotoxin HuM195/rGel on normal human bone marrow before clinical purging. HuM195/rGel is composed of the recombinant plant toxin gelonin (rGel) chemically coupled to the anti-CD33 human chimeric antibody HuM195. The CD33 antigen is of significant interest as a target for therapy of acute myelogenous leukemia because it is present in leukemic blasts of most patients but absent in the earliest progenitor bone marrow cells. HuM195/rGel was optimally cytotoxic to acute myelogenous leukemia HL60 cells with 24 hours of exposure. We developed an in vivo purging model by mixing mobilized peripheral blood progenitor cells with HL60 cells to simulate a remission in bone marrow. Cells were treated with 10 nmol/L of HuM195/rGel either with or without exposure to freeze/thaw procedure, which has been reported to act synergistically with HuM195/rGel to produce cytotoxic effect. When clonogenic cell recovery rates were determined, HuM195/rGel alone did not affect normal peripheral blood progenitor cells, whereas HuM195/rGel plus freeze/thaw provided 2 logs of tumor cell elimination in our purging model. We also observed similar results under conditions used in the transplantation setting. We concluded that for acute myelogenous leukemia blasts expressing CD33, HuM195/rGel could be useful as a purging reagent for autologous transplantation.