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The duration of immunodeficiency following marrow transplantation is not known. Questionnaires were used to study the infection rates in 72 patients surviving 20 to 30 years after marrow grafting. Furthermore, in 33 of the 72 patients and in 16 donors (siblings who originally donated the marrow) leukocyte subsets were assessed by flow cytometry. T-cell receptor excision circles (TRECs), markers of T cells generated de novo, were quantitated by real-time polymerase chain reaction. Immunoglobulin G(2) (IgG(2)) and antigen-specific IgG levels were determined by enzyme-linked immunosorbent assay. Infections diagnosed more than [corrected] 15 years after transplantation occurred rarely. The average rate was 0.07 infections per patient-year (one infection every 14 years), excluding respiratory tract infections, gastroenteritis, lip sores, and hepatitis C. The counts of circulating monocytes, natural killer cells, B cells, CD4 T cells, and CD8 T cells in the patients were not lower than in the donors. The counts of TREC(+) CD4 T cells in transplant recipients younger than age 18 years (at the time of transplantation) were not different from the counts in their donors. In contrast, the counts of TREC(+) CD4 T cells were lower in transplant recipients age 18 years or older, even in those with no history of clinical extensive chronic graft-versus-host disease, compared with their donors. The levels of total IgG(2) and specific IgG against Haemophilus influenzae and Streptococcus pneumoniae were similar in patients and donors. Overall, the immunity of patients surviving 20 to 30 years after transplantation is normal or near normal. Patients who received transplants in adulthood have a clinically insignificant deficiency of de novo-generated CD4 T cells, suggesting that in these patients the posttransplantation thymic insufficiency may not be fully reversible.

This study compared the incidence of clinical extensive chronic graft-versus-host disease (GVHD), transplantation-related mortality, survival, and relapse-free survival among recipients randomly assigned to receive a 24-month or a 6-month course of cyclosporine prophylaxis after transplantation of allogeneic marrow from an HLA-identical sibling or alternative donor. Patients who did not have clinical manifestations of chronic GVHD on day 80 after transplantation were eligible for the study if they previously had acute GVHD or if a skin biopsy showed histologic evidence of chronic GVHD. Clinical extensive chronic GVHD developed in 35 of the 89 patients (39%) in the 24-month group and 37 of the 73 patients (51%) in the 6-month group. The hazard of developing chronic GVHD was not significantly different in the 2 groups (hazard ratio = 0.76; 95% confidence interval, 0.48-1.21; P =.25). In addition, there were no significant differences between the 2 groups in transplantation-related mortality, survival, or disease-free survival.

Cyclosporine A (CsA) inhibits P-glycoprotein (Pgp)-mediated cellular export of anthracyclines at clinically achievable concentrations. This randomized controlled trial was performed to test the benefit of CsA addition to treatment with cytarabine and daunorubicin (DNR) in patients with poor-risk acute myeloid leukemia (AML). A total of 226 patients were randomly assigned to sequential treatment with cytarabine and infusional DNR with or without intravenous CsA. Remitting patients received one course of consolidation chemotherapy that included DNR with or without CsA as assigned during induction. Addition of CsA significantly reduced the frequency of resistance to induction chemotherapy (31% versus 47%, P =.0077). Whereas the rate of complete remission was not significantly improved (39% versus 33%, P =.14), relapse-free survival (34% versus 9% at 2 years, P =.031) and overall survival (22% versus 12%, P =.046) were significantly increased with CsA. The effect of CsA on survival was greatest in patients with moderate or bright Pgp expression (median 12 months with CsA versus 4 months for controls) compared to patients with absent or low Pgp expression (median 6 months in both arms). The frequency of induction deaths was 15% with CsA and 18% in controls. Steady-state serum concentrations of DNR (P =.0089) and daunorubicinol (P <.0001) were significantly higher in CsA-treated patients. Survival (P =.0003) and induction response (P =.028) improved with increasing DNR concentration in CsA-treated patients but not in controls, suggesting a targeted interaction by CsA to enhance anthracycline cytotoxicity. These results indicate that addition of CsA to an induction and consolidation regimen containing infusional DNR significantly reduces resistance to DNR, prolongs the duration of remission, and improves overall survival in patients with poor-risk AML.

The bcr-abl chimeric messenger RNA is frequently detected in chronic myeloid leukemia (CML) patients after bone marrow transplantation. It was previously reported that the relapse risk of bcr-abl detection 6 to 12 months after transplantation was greater than 40%. This risk decreased as the time between transplantation and detection increased. To further define the relapse risk associated with bcr-abl molecular detection in "late" CML survivors, 379 consecutive CML patients alive at 18 months after transplantation or later were studied. Ninety of 379 patients (24%) had at least one positive bcr-abl test 18 months after transplantation or later; 13 of 90 bcr-abl-positive patients (14%) and 3 of 289 bcr-abl-negative patients (1.0%) relapsed. The median time from bcr-abl detection to relapse was 916 days (range, 251-2654 days). The hazard ratio of relapse associated with bcr-abl detection was 19.2 (P <.0001). The stage of disease, chronic graft-versus-host disease, and the donor type did not alter the association between bcr-abl and relapse. Quantification of bcr-abl was performed on 344 samples from 85 bcr-abl-positive patients by means of a real-time quantitative reverse transcriptase-polymerase chain reaction assay. The median bcr-abl change of patients who relapsed was significantly greater than those that remained in remission (P =.002). The median bcr-abl level at relapse was 40 443 bcr-abl copies per microg RNA (range, 960-299 552). Of 73 bcr-abl-positive patients who failed to relapse, 69% had only one positive test at a median of 24 copies bcr-abl per microg RNA. The detection of bcr-abl is common following transplantation. The prognostic significance of a qualitative bcr-abl can be refined by quantitative assays and thus may target patients who would benefit from early intervention.

Expression of multidrug resistance (MDR) features by acute myeloid leukemia (AML) cells predicts a poor response to many treatments. The MDR phenotype often correlates with expression of P-glycoprotein (Pgp), and Pgp antagonists such as cyclosporine (CSA) have been used as chemosensitizing agents in AML. Gemtuzumab ozogamicin, an immunoconjugate of an anti-CD33 antibody linked to calicheamicin, is effective monotherapy for CD33(+) relapsed AML. However, the contribution of Pgp to gemtuzumab ozogamicin resistance is poorly defined. In this study, blast cell samples from relapsed AML patients eligible for gemtuzumab ozogamicin clinical trials were assayed for Pgp surface expression and Pgp function using a dye efflux assay. In most cases, surface expression of Pgp correlated with Pgp function, as indicated by elevated dye efflux that was inhibited by CSA. Among samples from patients who either failed to clear marrow blasts or failed to achieve remission, 72% or 52%, respectively, exhibited CSA-sensitive dye efflux compared with 29% (P =.003) or 24% (P <.001) among samples from responders. In vitro gemtuzumab ozogamicin--induced apoptosis was also evaluated using an annexin V--based assay. Low levels of drug-induced apoptosis were associated with CSA-sensitive dye efflux, whereas higher levels correlated strongly with achievement of remission and marrow blast clearance. In vitro drug-induced apoptosis could be increased by CSA in 14 (29%) of 49 samples exhibiting low apoptosis in the absence of CSA. Together, these findings indicate that Pgp plays a role in clinical resistance to gemtuzumab ozogamicin and suggest that treatment trials combining gemtuzumab ozogamicin with MDR reversal agents are warranted. (Blood. 2001;98:988-994)

Current therapeutic options for myeloid metaplasia with myelofibrosis (MMM) are limited. A pilot study was conducted of autologous peripheral blood stem cell (PBSC) collection in 27, followed by transplantation in 21 patients with MMM. The median age was 59 (range 45-75) years. PBSCs were mobilized at steady state (n = 2), after granulocyte colony-stimulating factor (G-CSF) alone (n = 17), or after anthracycline-cytarabine induction plus G-CSF (n = 8). A median of 11.6 x 10(6) (range 0 to 410 x 10(6)) CD34(+) cells per kilogram were collected. Twenty-one patients then underwent myeloablation with oral busulfan (16 mg/kg) and PBSC transplantation. The median times to neutrophil and platelet recovery after transplantation were 21 (range 10-96) and 21 (range, 13 to > or = 246) days, respectively. Five patients received back-up PBSC infusion because of delayed neutrophil or platelet recovery. The median follow-up is 390 (range 70-1623) days after transplantation, and the 2-year actuarial survival is 61%. After transplantion, 6 patients died: 3 of nonrelapse causes (1 within 100 days of PBSC infusion) and 3 of disease progression. Erythroid response (hemoglobin > or = 100 g/L [10 gm/dL] without transfusion for > or = 8 weeks) occurred in 10 of 17 anemic patients. Four of 8 patients with a platelet count less than 100 x 10(9)/L (100 000/microL) responded with a durable platelet count more than 100 x 10(9)/L (100 000/microL). Symptomatic splenomegaly improved in 7 of 10 patients. It is concluded that (1) PBSC collection was feasible and stable engraftment occurred after transplantation in most patients with MMM, (2) myeloablation with busulfan was associated with acceptable toxicity, (3) a significant proportion of patients derived clinical benefit after treatment, and (4) further investigation of this novel approach is warranted. (Blood. 2001;98:586-593)

Toxicities have limited the use of allogeneic hematopoietic cell transplantation (HCT) to younger, medically fit patients. In a canine HCT model, a combination of postgrafting mycophenolate mofetil (MMF) and cyclosporine (CSP) allowed stable allogeneic engraftment after minimally toxic conditioning with low-dose (200 cGy) total-body irradiation (TBI). These findings, together with the known antitumor effects of donor leukocyte infusions (DLIs), led to the design of this trial. Forty-five patients (median age 56 years) with hematologic malignancies, HLA-identical sibling donors, and relative contraindications to conventional HCT were treated. Immunosuppression involved TBI of 200 cGy before and CSP/MMF after HCT. DLIs were given after HCT for persistent malignancy, mixed chimerism, or both. Regimen toxicities and myelosuppression were mild, allowing 53% of eligible patients to have entirely outpatient transplantations. Nonfatal graft rejection occurred in 20% of patients. Grades II to III acute graft-versus-host disease (GVHD) occurred in 47% of patients with sustained engraftment. With median follow-up of 417 days, survival was 66.7%, nonrelapse mortality 6.7%, and relapse mortality 26.7%. Fifty-three percent of patients with sustained engraftment were in complete remission, including 8 with molecular remissions. This novel allografting approach, based on the use of postgrafting immunosuppression to control graft rejection and GVHD, has dramatically reduced the acute toxicities of allografting. HCT with the induction of potent graft-versus-tumor effects can be performed in previously ineligible patients, largely in an outpatient setting. Future protocol modifications should reduce rejection and GVHD, thereby facilitating studies of allogeneic immunotherapy for a variety of malignancies. (Blood. 2001;97:3390-3400)

The prevalence and significance of genetic abnormalities in older patients with acute myeloid leukemia (AML) are unknown. Polymerase chain reactions and single-stranded conformational polymorphism analyses were used to examine 140 elderly AML patients enrolled in the Southwest Oncology Group study 9031 for FLT3, RAS, and TP53 mutations, which were found in 34%, 19%, and 9% of patients, respectively. All but one of the FLT3 (46 of 47) mutations were internal tandem duplications (ITDs) within exons 11 and 12. In the remaining case, a novel internal tandem triplication was found in exon 11. FLT3 ITDs were associated with higher white blood cell counts, higher peripheral blast percentages, normal cytogenetics, and less disease resistance. All RAS mutations (28 of 28) were missense point mutations in codons 12, 13, or 61. RAS mutations were associated with lower peripheral blast and bone marrow blast percentages. Only 2 of 47 patients with FLT3 ITDs also had a RAS mutation, indicating a significant negative association between FLT3 and RAS mutations (P =.0013). Most TP53 mutations (11 of 12) were missense point mutations in exons 5 to 8 and were associated with abnormal cytogenetics, especially abnormalities in both chromosomes 5 and 7. FLT3 and RAS mutations were not associated with inferior clinical outcomes, but TP53 mutations were associated with a worse overall survival (median 1 versus 8 months, P =.0007). These results indicate that mutations in FLT3, RAS, or TP53 are common in older patients with AML and are associated with specific AML phenotypes as defined by laboratory values, cytogenetics, and clinical outcomes. (Blood. 2001;97:3589-3595)

Allogeneic peripheral blood stem cell grafts contain about 10 times more T and B cells than marrow grafts. Because these cells may survive in transplant recipients for a long time, recipients of blood stem cells may be less immunocompromised than recipients of marrow. Immune reconstitution was studied in 115 patients randomly assigned to receive either allogeneic marrow or filgrastim-mobilized blood stem cell transplantation. Between day 30 and 365 after transplantation, counts of most lymphocyte subsets were higher in the blood stem cell recipients. The difference was most striking for CD4 T cells (about 4-fold higher counts for CD45RA(high) CD4 T cells and about 2-fold higher counts for CD45RA(low/-)CD4 T cells; P <.05). On assessment using phytohemagglutinin and herpesvirus antigen-stimulated proliferation, T cells in the 2 groups of patients appeared equally functional. Median serum IgG levels were similar in the 2 groups. The rate of definite infections after engraftment was 1.7-fold higher in marrow recipients (P =.001). The rate of severe (inpatient treatment required) definite infections after engraftment was 2.4-fold higher in marrow recipients (P =.002). The difference in the rates of definite infections was greatest for fungal infections, intermediate for bacterial infections, and lowest for viral infections. Death associated with a fungal or bacterial infection occurred between day 30 and day 365 after transplantation in 9 marrow recipients and no blood stem cell recipients (P =.008). In conclusion, blood stem cell recipients have higher lymphocyte-subset counts and this appears to result in fewer infections. (Blood. 2001;97:3380-3389)

The experiences of 69 (38 marrow and 31 peripheral blood stem cell [PBSC]) donors participating in a randomized trial comparing allogeneic bone marrow with PBSC transplantation were studied. Marrow was collected by means of standard harvest techniques and general or regional anesthesia. PBSC donors were treated with 5 to 7 days of filgrastim at a dose of 16 microg/kg/d and underwent 1 to 3 days of apheresis to obtain 5 x 10(6) CD34(+) cells per kilogram recipient weight. Donors completed questionnaires describing their health experiences before, during, and then weekly after donation until return to baseline status. Both marrow and PBSC donors reported minimal fluctuation in symptoms measuring emotional status. In contrast, both groups of donors reported deterioration in physical status starting with administration of filgrastim (PBSC donors) or after the marrow collection procedure. The symptom burden reported was similar, with pain a prominent symptom for both groups. Equivalent mean levels of maximal pain, average pain, and pain duration through the day were reported, although toxicity peaks occurred at different time points during the harvest procedures. All PBSC donors but only 79% of marrow donors reported good physical status by 14 days after the harvest procedures. These data demonstrate similar levels of physical discomfort for hematopoietic stem cell donors regardless of the collection procedure used, but a quicker resolution of symptoms for PBSC donors.

The associations of cytogenetics with complete remission (CR) rates, overall survival (OS), and outcomes after CR were studied in 609 previously untreated AML patients younger than 56 years old in a clinical trial comparing 3 intensive postremission therapies: intensive chemotherapy, autologous transplantation (ABMT), or allogeneic bone marrow transplantation (alloBMT) from matched related donors. Patients were categorized into favorable, intermediate, unfavorable, and unknown cytogenetic risk groups based on pretreatment karyotypes. CR rates varied significantly (P <.0001) among the 4 groups: favorable, 84% (95% confidence interval [CI], 77%-90%); intermediate, 76% (CI, 71%-81%); unfavorable, 55% (CI, 48%-63%); and unknown, 54% (CI, 33%-74%). There was similar significant heterogeneity of OS (P <.0001), with the estimated relative risk of death from any cause being 1.50 (CI, 1.10-2.05), 3. 33 (CI, 2.43-4.55), and 2.66 (CI, 1.59-4.45) for the intermediate, unfavorable, and unknown risk groups, respectively, compared with the favorable group. In multivariate analyses, the effects of cytogenetic risk status on CR rate and OS could not be explained by other patient or disease characteristics. Among postremission patients, survival from CR varied significantly among favorable, intermediate, and unfavorable groups (P =.0003), with significant evidence of interaction (P =.017) between the effects of treatment and cytogenetic risk status on survival. Patients with favorable cytogenetics did significantly better following ABMT and alloBMT than with chemotherapy alone, whereas patients with unfavorable cytogenetics did better with alloBMT. Cytogenetic risk status is a significant factor in predicting response of AML patients to therapy; however, to tighten treatment correlates within genetically defined AML subsets, a significantly larger leukemia cytogenetic database is warranted.

In a randomized, placebo-controlled, double-blind trial, thalidomide or placebo together with glucocorticoids and either cyclosporine or tacrolimus was administered as initial therapy for clinical extensive chronic graft-versus-host disease (cGVHD). All patients had thrombocytopenia or cGVHD that evolved directly from acute GVHD as an indicator of a poor prognosis. The study drug (thalidomide or placebo) was administered initially at a dose of 200 mg orally per day, followed by a gradual increase to 800 mg/d if side effects were tolerable. Treatment with the study drug was discontinued before resolution of cGVHD in 23 (92%) of the 25 patients who received thalidomide and in 17 (65%) of the 26 patients who received placebo (P =.02). Neutropenia and neurologic symptoms were the most frequent reasons for early discontinuation of treatment with thalidomide. The duration of treatment with thalidomide was too short to assess its efficacy in controlling cGVHD. (Blood. 2000;96:3995-3996)

Relapsed B-cell lymphomas are incurable with conventional chemotherapy and radiation therapy, although a fraction of patients can be cured with high-dose chemoradiotherapy and autologous stem-cell transplantation (ASCT). We conducted a phase I/II trial to estimate the maximum tolerated dose (MTD) of iodine 131 ((131)I)-tositumomab (anti-CD20 antibody) that could be combined with etoposide and cyclophosphamide followed by ASCT in patients with relapsed B-cell lymphomas. Fifty-two patients received a trace-labeled infusion of 1.7 mg/kg (131)I-tositumomab (185-370 MBq) followed by serial quantitative gamma-camera imaging and estimation of absorbed doses of radiation to tumor sites and normal organs. Ten days later, patients received a therapeutic infusion of 1.7 mg/kg tositumomab labeled with an amount of (131)I calculated to deliver the target dose of radiation (20-27 Gy) to critical normal organs (liver, kidneys, and lungs). Patients were maintained in radiation isolation until their total-body radioactivity was less than 0.07 mSv/h at 1 m. They were then given etoposide and cyclophosphamide followed by ASCT. The MTD of (131)I-tositumomab that could be safely combined with 60 mg/kg etoposide and 100 mg/kg cyclophosphamide delivered 25 Gy to critical normal organs. The estimated overall survival (OS) and progression-free survival (PFS) of all treated patients at 2 years was 83% and 68%, respectively. These findings compare favorably with those in a nonrandomized control group of patients who underwent transplantation, external-beam total-body irradiation, and etoposide and cyclophosphamide therapy during the same period (OS of 53% and PFS of 36% at 2 years), even after adjustment for confounding variables in a multivariable analysis.

We examined the incidence, clinical course, and outcome of patients with newly diagnosed acute promyelocytic leukemia (APL) who developed the retinoic acid syndrome (RAS) treated on the Intergroup Protocol 0129, which prospectively evaluated the role of alltrans retinoic acid (ATRA) alone during induction and as maintenance therapy. Forty-four of 167 (26%) patients receiving ATRA for induction developed the syndrome at a median of 11 days of ATRA (range, 2-47). The median white blood cell (WBC) count was 1,450/microL at diagnosis and was 31,000/microL (range, 6,800-72,000/microL) at the time the syndrome developed. ATRA was discontinued in 36 of the 44 patients (82%) and continued in 8 patients (18%), with subsequent resolution of the syndrome in 7 of the 8. ATRA was resumed in 19 of the 36 patients (53%) in whom ATRA was stopped and not in 17 (47%). The syndrome recurred in 3 of those 19 patients, with 1 death attributable to resumption of the drug. Ten of these 36 patients received chemotherapy without further ATRA, and 8 achieved complete remission (CR). Among 7 patients in whom ATRA was not restarted and were not treated with chemotherapy, 5 achieved CR and 2 died. Two deaths were definitely attributable to the syndrome. No patient receiving ATRA as maintenance developed the syndrome. (Blood. 2000;95:90-95)

High-dose therapy with autologous peripheral blood stem cell (PBSC) rescue is widely used for the treatment of malignant disease. CD34 selection of PBSC has been applied as a means of reducing contamination of the graft. Although CD34 selection results in a 2 to 3 log reduction in contaminating tumor cells without significantly delaying engraftment, many other types of cells are depleted from the CD34-enriched grafts and immune reconstitution may be impaired. In the present study, 31 cytomegalovirus (CMV)-seropositive patients who received myeloablative therapy followed by the infusion of CD34-selected autologous PBSC were assessed for the development of CMV disease in the first 100 days posttransplant. Seven patients (22.6%) developed CMV disease and 4 patients (12.9%) died from complications of their infection. In a contemporaneous group of 237 CMV-seropositive patients receiving unselected, autologous PBSC, only 10 patients (4.2%) developed CMV disease, with 5 deaths (2.1%). In a multivariate logistic regression analysis, the use of CD34-selected autologous PBSC after high-dose therapy was associated with a marked increase in the incidence of CMV disease and CMV-associated deaths.

We conducted a phase I-II clinical trial to test the hypothesis that removal of CD4 cells from an HLA-mismatched unrelated marrow graft would substantially reduce the risk of grades III-IV graft-versus-host disease (GVHD) and that retention of a specified number of CD8 cells in the graft would be sufficient to prevent rejection. Patients were eligible for this study when an HLA-A, -B, or -DRB1-matched unrelated donor could not be identified. HLA matching of the donor and recipient was based on typing of HLA-A and -B antigens by serologic methods and by typing of HLA-DRB1 alleles by molecular methods, and donors were selected when disparity was limited to a single HLA-DRB1 allele or a single HLA-A or -B antigen. Twenty-seven patients with hematologic malignancy or aplastic anemia were prepared to receive a transplant with conventional regimens of cyclophosphamide and fractionated total body irradiation, and a standard regimen of methotrexate and cyclosporine was given for GVHD prophylaxis. CD4 cells were removed from the donor marrow, and the numbers of CD8 cells were adjusted systematically in graded steps for successive patients, depending on the occurrence of grades III-IV GVHD or graft failure in previously enrolled patients. Removal of CD4 cells did not cause graft rejection or appreciably decrease the risk of grades III-IV GVHD. Depletion of CD8 cells was associated with an increased risk of rejection with either HLA-DRB1 disparity or with HLA-A or -B disparity. With either type of disparity, the risk of grades III-IV GVHD is likely to be higher than 15% at any dose of CD8 cells associated with less than 5% risk of graft failure. The absence of graft failure associated with CD4 depletion supports the hypothesis that donor CD4 cells are not essential for preventing marrow graft rejection in humans. The correlation between graft failure and the number of CD8 cells in the donor marrow supports the hypothesis that donor CD8 cells help to prevent marrow graft rejection.

Because there are differing opinions regarding treatment of patients in the chronic phase of chronic myeloid leukemia (CML), the American Society of Hematology convened an expert panel to review and document evidence-based benefits and harms of treatment of CML with busulfan (BUS), hydroxyurea (HU), recombinant interferon-alpha (rIFN-alpha), and bone marrow transplantation (BMT). The primary measure for defining efficacy was survival. Analysis indicated a survival advantage for HU over BUS. Observational studies of rIFN-alpha suffer from numerous biases including sample size, variations in study populations, definitions of hematologic and cytogenetic remissions, and dose. That rIFN-alpha is more efficacious than chemotherapy is demonstrated by 6 prospective randomized trials. For patients with favorable clinical features in chronic phase, compared to HU and BUS, rIFN-alpha improves survival by a median of about 20 months. Most evidence suggests that rIFN-alpha is most effective when combined with other drugs and when given during the earliest stage of the chronic phase. Adding cytarabine to rIFN-alpha adds further survival benefit but increases toxicity. Limitations for evaluating the long-term benefits of allogeneic BMT include the retrospective nature of most studies, incomplete documentation of the clinical characteristics of the patients, paucity of the details on patient selection, lack of control groups, and limitations of survival calculations. Survival curves for BMT show that at least half of the patients transplanted remain alive 5 to 10 years after treatment, whereas similar curves for rIFN-alpha show a continuous relapse rate over time with the curves crossing at about 7 to 8 years. Estimates of long-term survival may be confounded by the selection biases mentioned and the analytic methods used. The magnitude of the incremental increase in benefit with BMT must be weighed against the potential serious harm and death that may accompany the procedure in the short term. The best results with BMT have been obtained when it is performed within 1 to 2 years from diagnosis. Since each treatment option involves tradeoffs between benefit and harm, patient choice must be based on the examination of facts presented in an unbiased fashion. Newly diagnosed younger patients and older patients who are candidates for BMT should also be offered information about IFN-based regimens, the tradeoffs involved, and, if possible, share in the treatment decision. Hopefully this analysis will provide the stimulus for evaluation of other important aspects of CML.

Delivery of targeted hematopoietic irradiation using radiolabeled monoclonal antibody may improve the outcome of marrow transplantation for advanced acute leukemia by decreasing relapse without increasing toxicity. We conducted a phase I study that examined the biodistribution of (131)I-labeled anti-CD45 antibody and determined the toxicity of escalating doses of targeted radiation combined with 120 mg/kg cyclophosphamide (CY) and 12 Gy total body irradiation (TBI) followed by HLA-matched related allogeneic or autologous transplant. Forty-four patients with advanced acute leukemia or myelodysplasia received a biodistribution dose of 0.5 mg/kg (131)I-BC8 (murine anti-CD45) antibody. The mean +/- SEM estimated radiation absorbed dose (centigray per millicurie of (131)I) delivered to bone marrow and spleen was 6.5 +/- 0.5 and 13.5 +/- 1.3, respectively, with liver, lung, kidney, and total body receiving lower amounts of 2.8 +/- 0.2, 1.8 +/- 0.1, 0.6 +/- 0.04, and 0.4 +/- 0.02, respectively. Thirty-seven patients (84%) had favorable biodistribution of antibody, with a higher estimated radiation absorbed dose to marrow and spleen than to normal organs. Thirty-four patients received a therapeutic dose of (131)I-antibody labeled with 76 to 612 mCi (131)I to deliver estimated radiation absorbed doses to liver (normal organ receiving the highest dose) of 3.5 Gy (level 1) to 12.25 Gy (level 6) in addition to CY and TBI. The maximum tolerated dose was level 5 (delivering 10.5 Gy to liver), with grade III/IV mucositis in 2 of 2 patients treated at level 6. Of 25 treated patients with acute myeloid leukemia (AML)/myelodysplastic syndrome (MDS), 7 survive disease-free 15 to 89 months (median, 65 months) posttransplant. Of 9 treated patients with acute lymphoblastic leukemia (ALL), 3 survive disease-free 19, 54, and 66 months posttransplant. We conclude that (131)I-anti-CD45 antibody can safely deliver substantial supplemental doses of radiation to bone marrow (approximately 24 Gy) and spleen (approximately 50 Gy) when combined with conventional CY/TBI.

Therapeutic resistance is a major obstacle in the treatment of acute myeloid leukemia (AML). Such resistance has been associated with rapid drug efflux mediated by the multidrug resistance gene 1 (MDR1; encoding P-glycoprotein) and more recently with expression of other novel proteins conferring multidrug resistance such as MRP1 (multidrug resistance-associated protein 1) and LRP (lung resistance protein). To determine the frequency and clinical significance of MDR1, MRP1, and LRP in younger AML patients, we developed multiparameter flow cytometric assays to quantify expression of these proteins in pretreatment leukemic blasts from 352 newly diagnosed AML patients (median age, 44 years) registered to a single clinical trial (SWOG 8600). Protein expression was further correlated with functional efflux by leukemic blasts [assessed using two substrates: Di(OC)(2) and Rhodamine 123] and with the ability of MDR-reversing agents to inhibit efflux in vitro. MDR1/P-glycoprotein expression, which was highly correlated with cyclosporine-inhibited efflux, was noted in only 35% of these younger AML patients, distinctly lower than the frequency of 71% we previously reported in AML in the elderly (Blood 89:3323, 1997). Interestingly, MDR1 expression and functional drug efflux increased with patient age, from a frequency of only 17% in patients less than 35 years old to 39% in patients aged 50 years (P =.010). In contrast, MRP1 was expressed in only 10% of cases and decreased with patient age (P =. 024). LRP was detected in 43% of cases and increased significantly with increasing white blood cell counts (P =.0015). LRP was also marginally associated with favorable cytogenetics (P =.012) and French-American-British (FAB) AML FAB subtypes (P =.013), being particularly frequent in M4/M5 cases. Only MDR1/P-glycoprotein expression and cyclosporine-inhibited efflux were significantly associated with complete remission (CR) rate (P(MDR1) =.012; P(efflux) =.039) and resistant disease (RD; P(MDR1) =.0007; P(efflux) =.0092). No such correlations were observed for MRP1 (P(CR) =.93; P(RD) =.55) or LRP (P(CR) =.50; P(RD) =.53). None of these parameters were associated with overall or relapse-free survival. Unexpectedly, a distinct and nonoverlapping phenotype was detected in 18% of these cases: cyclosporine-resistant efflux not associated with MDR1, MRP1, or LRP expression, implying the existence of other as yet undefined efflux mechanisms in AML. In summary, MDR1 is less frequent in younger AML patients, which may in part explain their better response to therapy. Neither MRP1 nor LRP are significant predictors of outcome in this patient group. Thus, inclusion of MDR1-modulators alone may benefit younger AML patients with MDR1(+) disease.

The apparent oral clearance (CL/F, mL/min) of busulfan was measured in 279 adolescent and adult patients. Significant (P <.05) determinants of CL/F by linear regression were: actual body weight (BW; r2 = 0.300), body surface area (BSA; r2 = 0.277), adjusted ideal body weight (AIBW; r2 = 0.265), and ideal body weight (IBW; r2 = 0.173); whereas body mass index (BMI), height, age, gender, and disease were less important predictors. CL/F (mL/min) for normal weight patients (BMI, 18 to 27 kg/m2) was 16.2% lower (P <.001) than for obese patients (BMI, 27 to 35 kg/m2). Thus, expressing CL/F relative to BW did not eliminate statistically significant differences between normal and obese patients. However, busulfan CL/F expressed relative to BSA (110 +/- 24 v 110 +/- 24 mL/min/m2, P = 1.0) or AIBW (3.04 +/- 0.65 v 3.19 +/- 0.67 mL/min/kg, P =.597) were similar in normal and obese patients. Non-Hodgkin's lymphoma patients (n = 10) had approximately 32% lower mean busulfan CL/F expressed relative to BW, BSA, or AIBW compared with patients with chronic myelogenous leukemia (n = 73). Routine dosing on the basis of BSA or AIBW in adults and adolescents does not require a specific accommodation for the obese. However, dosing based on BSA may be improved by considering CL/F differences in certain diseases. Adjusting dose for body size or disease does not diminish interpatient variability sufficiently to obviate plasma level monitoring in many indications.

Leukemic blast cells express the CD33 antigen in most patients with acute myeloid leukemia (AML), but this antigen is not expressed by hematopoietic stem cells. We conducted a study to determine whether normal hematopoiesis could be restored in patients with AML by selective ablation of cells expressing the CD33 antigen. In a dose escalation study, 40 patients with relapsed or refractory CD33(+) AML were treated with an immunoconjugate (CMA-676) consisting of humanized anti-CD33 antibody linked to the potent antitumor antibiotic calicheamicin. The capacity of leukemic cells to efflux 3, 3'-diethyloxacarbocyanine iodide (DiOC2) was used to estimate pretreatment functional drug resistance. Leukemia was eliminated from the blood and marrow of 8 (20%) of the 40 patients; blood counts returned to normal in three (8%) patients. A high rate of clinical response was observed in leukemias characterized by low dye efflux in vitro. Infusions of CMA-676 were generally well tolerated, and a postinfusion syndrome of fever and chills was the most common toxic effect. Two patients who were treated at the highest dose level (9 mg/m2) were neutropenic >5 weeks after the last dose of CMA-676. These results show that an immunoconjugate targeted to CD33 can selectively ablate malignant hematopoiesis in some patients with AML.

Targeted hematopoietic irradiation delivered by 131I-anti-CD45 antibody has been combined with conventional marrow transplant preparative regimens in an effort to decrease relapse. Before increasing the proportion of therapy delivered by radiolabeled antibody, the myeloablative and immunosuppressive effects of such low dose rate irradiation must be quantitated. We have examined the ability of 131I-anti-CD45 antibody to facilitate engraftment in Ly5-congenic and H2-mismatched murine marrow transplant models. Recipient B6-Ly5(a) mice were treated with 30F11 antibody labeled with 0.1 to 1.5 mCi 131I and/or total body irradiation (TBI), followed by T-cell-depleted marrow from Ly5(b)-congenic (C57BL/6) or H2-mismatched (BALB/c) donors. Engraftment was achieved readily in the Ly5-congenic setting, with greater than 80% donor granulocytes and T cells after 0.5 mCi 131I (estimated 17 Gy to marrow) or 8 Gy TBI. A higher TBI dose (14 Gy) was required to achieve engraftment of H2-mismatched marrow, and engraftment occurred in only 3 of 11 mice receiving 1.5 mCi 131I delivered by anti-CD45 antibody. Engraftment of H2-mismatched marrow was achieved in 22 of 23 animals receiving 0.75 mCi 131I delivered by anti-CD45 antibody combined with 8 Gy TBI. Thus, targeted radiation delivered via 131I-anti-CD45 antibody can enable engraftment of congenic marrow and can partially replace TBI when transplanting T-cell-depleted H2-mismatched marrow.

We analyzed results of 40 infants less than 2 years of age who received bone marrow transplants (BMT) between May 1974 and January 1995 for treatment of acute myelogenous leukemia (AML; N = 34) or myelodysplastic syndrome (MDS; N = 6) to determine outcome and survival performance. Among the AML patients, 13 were in first remission, 9 were in untreated first relapse or second remission, and 12 were in refractory relapse. Patients were conditioned with cyclophosphamide in combination with either total body irradiation (TBI; N = 29) or busulfan (N = 11). Source of stem cells included 6 autologous donors, 15 HLA genotypically identical siblings, 14 haploidentical family members, and 5 unrelated donors. Graft-versus-host disease (GVHD) prophylaxis was methotrexate (MTX) for 17, MTX plus cyclosporine (CSP) for 14, or CSP plus prednisone for 3. Incidence of severe (grade 3-4) regimen-related toxicity was 10% and transplant-related mortality was 10%. Acute GVHD (grades II-III) occurred in 39% of allogeneic patients, and chronic GVHD developed in 40%. Relapse, the most significant problem for patients in this study, occurred in 1 MDS patient and 23 AML patients and was the cause of death for 19 patients. The 2-year probabilities of relapse are 46%, 67%, and 92%, respectively, for patients transplanted in first remission, untreated first relapse or second remission, and relapse. One MDS and 8 AML patients received second marrow transplants for treatment of relapse, and 5 of these survive disease-free for more than 1.5 years. All 6 MDS patients and 11 of 34 AML patients survive more than 1.5 years later. The 5-year probabilities of survival and disease-free survival are 54% and 38% for patients transplanted in first remission and 33% and 22% for untreated first relapse or second remission. None of the patients transplanted with refractory relapse survive disease-free. Outcome was significantly associated with phase of disease at transplantation and pretransplant diagnosis of extramedullary disease. Long-term sequelae included growth failure and hormonal deficiencies. Survival performance was a median of 100% (80% to 100%) and neurologic development for all survivors was appropriate for age. This study indicates that infants with AML have similar outcome after BMT compared with older children and that BMT should be performed in first remission whenever possible. In addition, allogeneic BMT provides effective therapy for the majority of infants with MDS.

Treatment options for patients diagnosed with chronic myelogenous leukemia (CML) in chronic phase (CP) who lack a suitable related donor for marrow transplantation include hydroxyurea, interferon-alpha (IFN-alpha), or transplantation from an unrelated donor (URD). Most studies support the view that treatment with IFN-alpha results in prolonged survival compared with hydroxyurea therapy. Some patients are offered URD transplantation as a second-line treatment; however, the impact of pretransplant IFN-alpha on the outcome of URD transplantation is uncertain. To address this question, we evaluated the effect of pretransplant IFN-alpha therapy in 184 patients undergoing URD transplantation for CML in CP at a single center. Of the 184 patients, 114 did not receive IFN-alpha, whereas 22, 23, and 25 patients received IFN-alpha for, respectively, 1 to 5, 6 to 12, and more than 12 months before transplant. Pretransplant IFN-alpha therapy administered for > or = 6 months was associated with an increased risk of severe (grades III-IV) acute graft-versus-host disease (GVHD; relative risk [RR], 3.0; 95% confidence interval [CI], 1.4 to 6.2; P = .004) and mortality (RR, 2. 1; 95% CI, 1.3 to 3.5; P = .003) relative to less than 6 months or no IFN-alpha therapy. Increased mortality occurred between 100 and 365 days after transplant (P = .005), was limited to patients with severe acute GVHD, and was due to chronic GVHD refractory to immunosuppressive therapy. Other variables associated with mortality included HLA-DRB1 or DQB1 (but not HLA-A or B) mismatched donors, age greater than 50 years, weight > or = 110% of ideal body weight, and the absence of cytomegalovirus (CMV) or fungal prophylaxis. For patients treated with IFN-alpha for less than 6 months before transplant, who were < or = 50 years of age, received a HLA-A, B, DRB1, and DQB1 matched URD transplant, and received CMV and fungal prophylaxis after transplant (n = 48), survival was 87% +/- 5% at 5 years. These data provide a rationale for immediate transplantation in preference to extended treatment with IFN-alpha when the patient is < or = 50 years of age and has an HLA-compatible unrelated volunteer donor.

Older age is a poor prognosis factor in acute myeloid leukemia (AML). This double-blind trial was designed to test the hypothesis that granulocyte colony-stimulating factor (G-CSF) used as supportive care could improve the treatment of elderly AML patients. Two hundred thirty-four patients 55 or more years of age with a morphologic diagnosis of de novo or secondary AML, French-American-British (FAB) M0-M7, excluding M3, were randomly assigned to a standard induction regimen (daunorubicin at 45 mg/m2 intravenously [IV] on days 1 through 3 and Ara-C at 200 mg/m2 IV continuous infusion on days 1 through 7) plus either placebo or G-CSF (400 microg/m2 IV over 30 minutes once daily). Results are reported here for 211 centrally confirmed cases of non-M3 AML. The two groups were well balanced in demographic, clinical, and hematological parameters, with median ages of 68 years in the G-CSF and 67 years in the placebo groups. The complete response (CR) rate was not significantly better in the G-CSF group: 50% in the placebo and 41% in the G-CSF group (one-tailed P = .89). Median overall survival was also similar, 9 months (95% confidence interval [CI], 7 to 10 months) in the placebo and 6 months (95% CI, 3 to 8 months) in the G-CSF arms (P = .71). We found a significant 15% reduction in the time to neutrophil recovery in the G-CSF group (P = .014). G-CSF had no impact on recovery from thrombocytopenia (P = .80) or duration of first hospitalization (P = .27). When infection complications were evaluated, G-CSF had a beneficial effect on the duration but not on incidence of infection. G-CSF patients had fewer days with fever and shorter duration of antibiotic use. However, there was no difference in the frequency of total documented infections or in the number of fatal infections (19% placebo v 20% G-CSF). In this study of elderly AML patients, G-CSF improved clinical parameters of duration of neutropenia and antibiotic use, but did not change CR rate or survival or shorten hospitalization.

Primary graft rejection after marrow transplantation occurs more frequently in patients receiving HLA-haploidentical compared with HLA-identical sibling transplants. Both human and experimental animal data suggest that the cells responsible for this phenomenon are either host natural killer (NK) cells, T cells, or both. To investigate the mechanisms of graft rejection, we have developed a canine model of marrow transplantation, which uses DLA-nonidentical unrelated donors in the absence of postgrafting immunosuppression. In this model most animals rejected their marrow grafts after a preparative regimen of 9.2 Gy total body irradiation (TBI). However, engraftment of DLA-nonidentical marrow can be facilitated when the recipients are pretreated with monoclonal antibody (MoAb) S5, which recognizes CD44. In this report, we extended these observations by first cloning the canine CD44 and, next, mapping the epitope recognized by S5, which was located in a region conserved among human and canine CD44 and was distinct from the hyaluronan binding domain. However, in vitro binding of S5 caused a conformational change in CD44, which allowed increased hyaluronan binding. Then, we reexamined the in vivo model of marrow transplantation and compared results with MoAb S5 to those with two other anti-CD44 MoAbs, IM7 and S3. Only MoAb S5 significantly increased the engraftment rate of DLA-nonidentical unrelated marrow, whereas the two other anti-CD44 MoAbs were ineffective. The enhanced in vivo effect was not related to differences in the MoAbs' avidities, since both S5 and IM7 had equivalent binding to CD44, but most likely related to the specific epitope that S5 recognizes. Thus, this study shows that the effect of the anti-CD44 MoAb S5 in facilitating engraftment is epitope specific and if one is to use an anti-CD44 to facilitate engraftment of marrow in humans, one cannot assume that any anti-CD44 would work.

Chronic graft-versus-host disease (GVHD) is likely caused by donor T lymphocytes. Because unmodified blood stem cell grafts contain one log more T lymphocytes than unmodified marrow grafts, we evaluated the incidence of chronic GVHD in previously reported 37 blood stem cell recipients and 37 computer-matched historical control marrow recipients (Bensinger et al, Blood 88:2794, 1996). All patients have been followed until death, relapse, or occurrence of chronic GVHD or for a minimum of 2 years. In a univariable proportional hazards regression model, the relative risk of developing clinical chronic GVHD (includes clinical limited and clinical extensive disease) by 2 years posttransplant among the peripheral blood stem cell recipients compared with the marrow recipients was 2.22 (95% confidence interval, 1.04 to 4.74; P = .039). For clinical extensive chronic GVHD, the relative risk was 2.37 (95% confidence interval, 1.07 to 5. 29; P = .035). In multivariable analyses, considering also the covariables of patient age, patient cytomegalovirus serostatus, and donor cytomegalovirus serostatus, the relative risks of clinical chronic GVHD and clinical extensive chronic GVHD were also greater than 2 (P < .05). We conclude that the transplantation of unmanipulated filgrastim-mobilized blood stem cells may result in a relatively high incidence of chronic GVHD.

In each case of acute promyelocytic leukemia (APL) one of three PML-RAR alpha mRNA types is produced, depending on the break/fusion site in the PML gene that is linked to a common RAR alpha gene segment: a short (S)-form type, PML exon 3 RAR alpha exon 3; a long (L)-form type, PML exon 6 RAR alpha exon 3; or a variable (V)-form type, variably deleted PML exon 6 RAR alpha exon 3. We evaluated whether PML-RAR alpha mRNA type is associated with distinct pretreatment clinical characteristics and therapeutic outcome in previously untreated adult APL patients registered to protocol INT 0129 by the Eastern Cooperative Oncology Group, the Southwest Oncology Group, and the Cancer and Leukemia Group B. Of 279 clinically eligible cases, 230 were molecularly evaluable, and of these, 111 were randomized to receive remission induction therapy with all-trans retinoic acid (ATRA) and 119 with conventional chemotherapy. Nine cases not excluded by central pathology review were PML-RAR alpha negative, and notably, none of five of these cases treated with ATRA achieved complete remission (CR). Among 221 PML-RAR alpha-positive cases, there were 82 S-form cases (37%), 121 L-form cases (55%), and 18 V-form cases (8%). Before any antileukemic therapy, the S-form type, compared with the L-form type, was associated with higher values for the white blood cell (WBC) count (median 2,500/microL v 1,600/microL; P = .009), the percentage of blood blasts plus promyelocytes (median 29% v 8.5%; P = .03), and the absolute blood blasts plus promyelocytes (884/microL v 126/microL; P = .019). Also, an increased percentage of S-form versus L-form cases had the M3 variant phenotype, 24% v 12% (P = .036). There were no differences between S-form and L-form cases in either CR rate (79% v 69%; P = .14) or disease free survival distribution (multivariate analysis adjusting for the association of S-form type and higher WBC count; P = .40). We conclude that the S-form type is associated with previously-identified adverse risk WBC parameters but that the identification of the S-form or L-form type of PML-RAR alpha mRNA, per se, does not predict clinical outcome or add to the value of an increased WBC count as a negative prognostic indicator in APL patients.

Transplantation of marrow from unrelated donors was investigated in patients with Philadelphia chromosome-positive (Ph1+) acute lymphoblastic leukemia (ALL) who lacked a suitable family donor. Eighteen patients underwent transplantation at our center between 1988 and 1995. The median patient age was 25 years (range, 1.7 to 51 years). Seven patients were in first complete remission, 1 in second remission, 3 in first relapse, and the remaining 7 had more advanced or chemotherapy refractory leukemia at transplant. All patients were conditioned with cyclophosphamide and total body irradiation followed by marrow transplants from closely HLA-matched, unrelated volunteers. Posttransplant graft-versus-host disease (GVHD) prophylaxis included methotrexate with either cyclosporine or FK506. Graft failure was not observed. Severe (grades III-IV) GVHD appeared in 6 of 17 evaluable patients and chronic extensive GVHD in 7 of 13 patients at risk. Five patients had recurrent ALL after transplantation and another 4 died from causes other than leukemia. Six patients transplanted in first remission, 2 in first relapse, and 1 in second remission remain alive and leukemia-free at a median follow-up of 17 months (range, 9 to 73 months). The probability of leukemia-free survival at 2 years is 49% +/- 12%. These data indicate that unrelated donor marrow transplantation is an effective treatment option for patients with early stage Ph1+ ALL without a family match and suggest that in such patients an unrelated donor search should be initiated as soon as possible after diagnosis.

Transplantation of hematopoietic stem cells from an HLA-compatible unrelated volunteer is an option for patients with acute leukemia lacking a family match. However, criteria for patient and donor selection and the most effective transplant procedures, including the number of hematopoietic cells, remain to be defined. We tested factors influencing outcome of 174 patients with primary acute leukemia receiving non-T-cell depleted marrow from unrelated donors. Median patient age was 20 years (range, 0.5 to 54 years). A multivariable analysis found that leukemia in remission at the time of transplantation was associated with improved leukemia-free survival (relative risk [RR] of treatment failure: 0.5, confidence interval [CI]: 0.3 to 0.7), and presence of blasts in the peripheral blood, as opposed to marrow involvement only or isolated extramedullary relapse, was associated with impaired outcome (RR of treatment failure: 2.5, CI: 1.7 to 5.0). The use of donors with a limited HLA-mismatch was associated with decreased leukemic relapse (RR: 0.5, CI: 0.3 to 0.9) but no improvement in leukemia-free survival compared with HLA-matched unrelated donors. Transplantation of a marrow cell dose above the median value of 3.65 x 10(8)/kg was associated with faster neutrophil (RR: 1.5, CI: 1.1 to 2.0) and platelet (RR: 4.5, CI: 2.7 to 7.5) engraftment, and decreased incidence of severe acute graft-versus-host disease (RR: 0.6, CI: 0.4 to 0.9). In patients transplanted in remission, the use of a marrow cell dose above the median translated into less nonleukemic death (RR: 0.2, CI: 0.1 to 0.4) and better leukemia-free survival (RR of treatment failure: 0.3, CI: 0.2 to 0.6). Transplant in remission with a high dose of marrow cells was associated with the best outcome in both children and adults.

Patients with a lymphohematopoietic malignancy considered to be at high risk for posttransplant relapse were enrolled in a study to compare the use of cyclosporine (CSP) as a single agent with a combination of methylprednisolone (MP) and CSP for graft-versus-host disease (GVHD) prophylaxis after marrow transplantation from an HLA-identical sibling donor. Sixty patients were randomized to receive CSP only and 62 were randomized to receive CSP plus MP. Daily CSP was started on day -1 (5 mg/kg/d intravenously) and administered at gradually reduced doses until day 180. MP was started on day 7 at 0.5 mg/kg/d, increased to 1.0 mg/kg/d on day 15, started on a taper schedule on day 29, and discontinued on day 72. All 104 evaluable patients (surviving > or =28 days) had sustained engraftment. The incidence rates of grades II-IV acute GVHD were 73% and 60% for patients receiving CSP and CSP plus MP, respectively (P = .01). No difference was seen for grades III-IV GVHD. However, chronic GVHD occurred somewhat more frequently in patients receiving CSP plus MP (44%) than in patients receiving only CSP (21%; P = .02). The incidence of de novo chronic GVHD was marginally higher in patients receiving CSP plus MP (P = .08). No significant differences in the risk of infections were observed. There was a suggestion that the risk of relapse was lower in patients receiving CSP plus MP (P = .10) and, although the overall survival in the two groups was not different (P = .44), there was a slight advantage in favor of CSP plus MP-treated patients for relapse-free survival (P = .07). These results suggest that prophylactic MP, when combined with CSP, has only limited efficacy in acute GVHD prevention and may increase the probability of chronic GVHD.

Compared with younger patients, elderly patients with acute myeloid leukemia (AML) respond poorly to conventional chemotherapy. To determine if this poor response is due to differences in the biologic characteristics of AML in the elderly, we studied 211 patients (161 de novo, 50 secondary AML) over 55 years of age (median, 68 years) registered to a single clinical trial for previously untreated AML (SWOG 9031, Phase III randomized trial of standard dose cytosine arabinoside and daunomycin + rhG-CSF). Pretreatment leukemic blasts were karyotyped and were also analyzed for intrinsic drug resistance by quantitating expression of the multidrug resistance glycoprotein MDR1 and functional drug efflux using sensitive flow cytometric techniques. Results were correlated with clinical variables and outcome. These elderly AML patients had a high frequency of unfavorable cytogenetics (32%), MDR1 protein expression (71%), and functional drug efflux (58%); each of these factors occurred at high frequencies in both de novo and secondary AML patients and was associated with a significantly poorer complete remission (CR) rate. In multivariate analysis, secondary AML (P = .0035), unfavorable cytogenetics (P = .0031), and MDR1 (P = .0041) were each significantly and independently associated with lower CR rates. Resistant disease was associated with unfavorable cytogenetics (P = .017) and MDR1 expression (P = .0007). Strikingly, elderly MDR1(-) de novo AML patients with favorable/intermediate cytogenetics had a CR rate of 81%; with increasing MDR1 expression, CR rate decreased in this cytogenetic group. MDR1(+) secondary AML patients with unfavorable cytogenetics had a CR rate of only 12%. Thus, AML in the elderly is associated with an increased frequency of unfavorable cytogenetics and MDR1 expression, both of which independently contribute to poor outcomes. The high frequencies of these features in both de novo and secondary elderly AML patients suggest a common biologic mechanism for these leukemias distinct from that in younger patients. Investigation of biologic parameters at diagnosis in AML in the elderly may help identify patients with a high likelihood of achieving CR with conventional regimens, as well as those who may require alternate regimens designed to overcome therapy resistance.

The influence of busulfan (BU) plasma concentration on outcome of transplantation from HLA identical family members for the treatment of chronic myelogenous leukemia (CML) was examined in 45 patients transplanted in chronic phase (CP) (n = 39) or accelerated phase (AP) (n = 6). All patients received the same regimen of BU, 16 mg/kg orally and cyclophosphamide (CY), 120 mg/kg intravenously. Plasma concentrations of BU at steady state (C(SS)BU) during the dosing interval were measured for each patient. The mean C(SS)BU was 917 ng/mL (range, 642 to 1,749; median, 917; standard deviation, 213). Of patients with C(SS)BU below the median, seven (five of 18 in CP and two of four in AP) developed persistent cytogenetic relapse and three of these patients died. There were no relapses in patients with C(SS)BU above the median. The difference in the cumulative incidence of relapse between the two groups was statistically significant (P = .0003). C(SS)BU was the only statistically significant determinant of relapse in univariable or multivariable analysis. The 3-year survival estimates were 0.82 and 0.64 for patients with C(SS)BU above and below the median (P = .33). There was no statistically significant association of C(SS)BU with survival or nonrelapse mortality, although the power to detect a difference in survival between 0.82 and 0.64 was only 0.24, similarly C(SS)BU above the median was not associated with an increased risk of severe regimen-related toxicity. We conclude that low BU plasma levels are associated with an increased risk of relapse.

Thirty-six patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) were studied for the presence of the bcr-abl fusion mRNA transcript after an allogeneic matched related (N = 12), partially matched related (N = 4), matched unrelated (N = 14), autologous (N = 5), or syngeneic (N = 1) bone marrow transplant (BMT). Seventeen were transplanted in relapse, and 19 were transplanted in remission. Twenty-three patients had at least one positive bcr-abl polymerase chain reaction (PCR) assay after BMT either before a relapse or without subsequent relapse. Ten of these 23 relapsed after a positive assay at a median time from first positive PCR assay of 94 days (range, 28 to 416 days). By comparison, only 2 relapses occurred in the 13 patients with no prior positive PCR assays; both patients had missed at least one scheduled follow-up assay and were not tested 2 months and 26 months before their relapse. The unadjusted relative risk (RR) of relapse associated with a positive PCR assay compared with a negative assay was 5.7 (95% confidence interval 1.2 to 26.0, P = .025). In addition, the data suggest that the type of bcr-abl chimeric mRNA detected posttransplant was associated with the risk of relapse: 7 of 10 patients expressing the p190 bcr-abl relapsed, compared with 1 of 8 who expressed only the p210 bcr-abl mRNA (P = .02, log-rank test). The RR of p190 bcr-abl positivity compared to PCR-negative patients was 11.2 (confidence interval 2.3-54.8, P = 0.003), whereas a positive test for p210 bcr-abl was apparently not associated with an increased relative risk. In separate multivariable models, PCR positivity remained a statistically significant risk factor for relapse after separately adjusting for donor (unrelated and partially matched v matched, autologous, and syngeneic), remission status at the time of transplant, the presence of acute graft-versus-host disease (GVHD), and type of conditioning regimen (total body irradiation dose of < or = 1,200 cGy v > 1,200 cGy). The PCR assay appears to be a useful test for predicting patients at high risk of relapse after BMT and may identify patients who might benefit from therapeutic interventions. The finding that the expression of p190 bcr-abl may portend an especially high risk of relapse suggests a different clinical and biologic behavior between p190 and p210 bcr-abl.

The purpose of this report is to describe the results of stem cell transplantation as initial treatment for secondary acute myeloid leukemia (AML). Forty-six patients (median age 42 years) with secondary AML (17 therapy-related, 29 myelodysplasia-related) who had not received remission induction chemotherapy underwent allogeneic (n = 43) or syngeneic (n = 3) transplantation. The 5-year actuarial disease-free survival was 24.4%, and the cumulative incidences of relapse and nonrelapse mortality were 31.3% and 44.3%, respectively. Lower peripheral blood blast count was associated with a lower risk of relapse (P = .05) and shorter time from AML diagnosis to transplant was associated with a lower risk of nonrelapse mortality (P = .02) and improved disease-free survival (P = .026). Patients with therapy-related secondary AML tended to have lower disease-free survival (P = .16) and a higher relapse rate (P = .16) than patients whose leukemia was not therapy-related. The results of these 46 previously untreated patients were compared to 20 patients (median age 36 years, 12 therapy-related, 8 myelodysplasia-related) transplanted with chemotherapy-sensitive disease after induction chemotherapy (first complete remission [n = 6], second complete remission [n = 3], first untreated relapse [n = 11]). We found no statistically significant difference in outcome between these 2 groups of patients. These results suggest that prompt transplantation should be considered after diagnosis of secondary AML or, if possible, high-risk myelodysplasia, particularly in patients with low peripheral blast counts. Innovative transplant strategies are needed to reduce the high risks of relapse and nonrelapse mortality seen in this patient population.

We have designed in vitro assays to investigate the possible association between apoptosis and chemotherapeutic sensitivity in acute myeloid leukemias (AMLs). Consistent low levels of spontaneous apoptosis were observed in myeloid cells from normal bone marrow samples, while untreated cells collected from 56 de novo AML patients showed variable apoptosis. Control myeloid cells showed increased apoptosis after in vitro treatments with daunomycin (DNR), cytosine arabinoside (ARA-C), or gamma irradiation (RAD). Most AML samples showed less treatment-associated apoptosis, suggesting that apoptosis responses to therapeutic agents may be frequently attenuated in AML. Certain cytogenetic abnormalities common in AML may affect apoptosis, as acute promyelocytic leukemia (APL) samples with t(15;17) karyotypes showed consistently low levels of spontaneous and treatment-associated apoptosis. Apoptosis assays may provide unique functional subtyping of AMLs, as other common cytogenetic subsets showed variable apoptosis. Altered function of two well-characterized regulators of apoptosis, BCL-2 and p53, was not entirely responsible for this variability. A genomic p53 mutation was found in only one AML sample. All samples that demonstrated the highest BCL-2-positive cell fractions showed low apoptosis, but reduced apoptosis was seen in both the presence and absence of BCL-2 overexpression. Finally, data from matched diagnosis and relapse sample pairs suggest that neither further reduced apoptosis nor additional BCL-2 overexpression is necessarily associated with disease progression.

Sixteen patients with advanced hematologic malignancies were transplanted with HLA-identical allogeneic peripheral blood stem cells (PBSCs) that were selected for CD34+ cells by an avidin-biotin immunoadsorption technique. The median age of patients was 48 years (range, 37 to 67). Patients received 12.0 or 13.2 Gy of total body irradiation followed by 120 mg/kg of cyclophosphamide. Normal donors received 16 mg/kg of granulocyte-colony stimulating factor on days 1 to 6 followed by PBSC harvests on days 4 to 7. PBSC harvests were processed each day on a single avidin-blotin column containing an antibody to the CD34 antigen and processed cells were infused without cryopreservation daily for 4 consecutive days. Prophylaxis against graft-versus-host disease (GVHD) consisted of cyclosporine alone for 5 patients and CSA plus methotrexate for 11 patients. A median of 18.64 (6.74 to 34.97) x 10(8) CD34+ cells/kg patient body weight were collected from each donor. A median of 8.96 (2.62 to 17.34) x 10(8) CD34+ cells/kg patient body weight were recovered after avidin-biotin adsorption which represented a median CD34+ cell yield of 53% (18% to 77%) with a median purity of 62% (34% to 82%). There was a reduction in CD3+ cells from a median of 557.26 (227.73 to 677.77) x 106/kg to 0.73 x 10(4)/kg (0.40 to 3.65), in CD4+ cells from 351.72 (194.47 to 520.11) x 10(6)/kg to 0.40 (0.15 to 1.03) x 10(4)/kg and in CD8+ cells from 169.74 (53.34 to 325.83) x 10(6)/ kg to 0.32 (0.12 to 2.71) x 10(4)/kg representing a median 2.8 (2.19 to 3.14) log reduction in T cells. One patient died of infection on day 3 posttransplant and was unevaluable for recovery of neutrophils. The median day to recovery of 500 neutrophils/mL was 15 (8 to 26) in the remaining 15 patients. Six of 16 patients falled to achieve a platelet count of 20,000/mL before death on days 3 to 97 of transplant-related complications. The median day to achieving platelets of 20,000 mL in the remaining 10 patients was 11 (7 to 31). Eight of 16 patients (50%) died between 3 and 97 days posttransplant, 7 of transplant-related causes, and 1 of progressive disease. Grade 2-4 acute GVHD occurred in 12 out of 14 (86%) and grades 3-4 in 6 out of 14 (43%) evaluable patients. Six of 8 evaluable patients developed clinical chronic GVHD and 1 developed subclinical chronic GVHD. Bone marrow and/or peripheral blood chimerism studies in 12 evaluable patients showed 97% to 100% donor type in 11 patients with 1 patient in relapse showing 40% donor cells 60 to 90 days posttransplant. Four of 16 patients (25%) are alive and disease-free 312 to 576 days after transplant. There were no episodes of graft failure or rejection. This study shows that allogeneic transplantation using CD34+ selected PBSC results in prompt and sustained engraftment. CD34+ selection, as employed in this preliminary study, however, resulted in an apparently higher rate of acute and chronic GVHD. However, The sample size is quite small and precludes a more definitive conclusion regarding GVHD.

Interest in high-dose cytarabine (HDAC) for both induction and postremission therapy for acute myeloid leukemia (AML) prompted the Southwest Oncology Group (SWOG) to initiate a randomized trial comparing HDAC with standard-dose cytarabine (SDAC) for remission induction of previously untreated AML and to compare high-dose treatment versus conventional doses for consolidation therapy. Patients less than 65 years of age with de novo or secondary AML were randomized for induction between SDAC 200 mg/ m2/d for 7 days by continuous infusion or HDAC at 2 g/ m2 intravenously every 12 hours for 12 doses; both groups received daunorubicin (DNR) at 45 mg/m2/d intravenously for 3 days. Complete responders to SDAC were randomized to receive either two additional courses of SDAC plus DNR or one course of HDAC plus DNR. Complete responders to HDAC were nonrandomly assigned to receive one additional course of HDAC plus DNR. Of patients randomized between SDAC (n = 493) and HDAC (n = 172) induction, 361 achieved complete remission (CR). The CR rate was slightly poorer with HDAC: 55% versus 58% with SDAC for patients aged less than 50, and 45% (HDAC) versus 53% (SDAC) for patients aged 50 to 64 (age-adjusted one-tailed P = .96). With a median follow-up time of 51 months, survival was not significantly better with HDAC (P = .41); the estimated survival rate at 4 years was 32% (HDAC) versus 22% (SDAC) for those aged less than 50, and 13% (HDAC) versus 11% (SDAC) for those aged 50 to 64. However, relapse-free survival was somewhat better following HDAC Induction (P = .049): 33% (HDAC) versus 21% (SDAC) at 4 years for those aged less than 50, and 21% (HDAC) versus 9% (SDAC) for those aged 50 to 64. Induction with HDAC was associated with a significantly increased risk of fatal (P = .0033) and neurologic (P < .0001) toxicity. Among patients who achieved CR with SDAC, survival and disease-free survival (DFS) following consolidation randomization were not significantly better with HDAC compared with SDAC (P = .77 and .46, respectively). Patients who received both HDAC induction and consolidation had the best postremission outcomes; however, the proportion of CR patients who did not go on to protocol consolidation therapy was more than twice as high after HDAC induction compared with SDAC. Induction therapy with HDAC plus DNR was associated with greater toxicity than SDAC plus DNR, but with no improvement in CR rate or survival. Following CR induction with SDAC, consolidation with HDAC increased toxicity but not survival or DFS. In a nonrandomized comparison, patients who received both HDAC induction and consolidation had superior survival and DFS compared with those who received SDAC induction with either SDAC or HDAC consolidation.

Allogeneic peripheral blood stem cell (PBSC) transplants from HLA-identical siblings were performed in 37 patients with advanced hematologic malignancies. Outcomes were compared to a historical group of 37 similar patients with advanced hematologic malignancies receiving bone marrow (BM) transplants from HLA-identical donors. The PBSC group and historical BM group were well matched for diagnosis, disease stage, age, and graft-versus-host disease (GVHD) prophylaxis. Patients received PBSC transplants between 1993 to 1995 while BM patients were treated between 1989 to 1994. Engraftment, measured by the time to reach a peripheral neutrophil count > 500/L and platelet count > 20,000/microL without transfusions, occurred on days 14 and 11 in the patients transplanted with PBSC compared to days 16 and 15 in the patients receiving BM (P = .00063, .00014). The PBSC group required a median of 8 U of red blood cells and 24 U of platelets compared to 17 U of red blood cells and 118 U of platelets for BM transplant recipients (P = .0005, .0001). The estimated risks of developing grades 2 to 4 acute GVHD were 37% for the PBSC group and 56% for the BM group (P = .18), while the estimated risks of grades 3 to 4 acute GVHD were 14% for the PBSC group and 33% for the BM group, P = .05). Chronic GVHD occurred in 7 of 18 evaluable patients receiving PBSC and 6 of 23 evaluable patients receiving BM, P = .5. The estimated risks of transplant-related mortality at 200 days were 27% versus 45% (P = .33) relapse were 70% versus 53% (P = .27) and of overall survival were 50% and 41% (P = .39) for patients transplanted with PBSC or BM, respectively. This retrospective comparison suggests that compared to marrow transplantation from HLA-identical donors, allogeneic PBSC transplantation from HLA-identical donors is associated with faster engraftment, fewer transfusions, and no greater incidence of acute or chronic GVHD.

Between September 1987 and December 1994, 80 patients with multiple myeloma (MM) received high-dose busulfan and cyclophosphamide without (n = 57) or with modified total body irradiation (n = 23) followed by marrow from allogeneic donors. At transplant, 71% of the patients had disease that was refractory to chemotherapy. Thirty-five patients died of transplant-related causes within 100 days and 11 deaths occurred later. The actuarial probabilities of survival and progression-free survival were .24 +/- 0.17 and .20 +/- 0.10 at 4.5 years. Complete remissions were obtained in 36% of patients who had actuarial probabilities of survival and event-free survival of .50 +/- 0.21 and .43 +/- 0.17 at 4.5 years. In a multivariate analysis, adverse risk factors for outcome endpoints included: transplantation greater than 1 year from diagnosis; beta-2 microglobulin > 2.5 at transplant; female patients transplanted from male donors; patients who had received greater than eight cycles of chemotherapy before transplant and Durie stage 3 disease at the time of transplant. These results indicate that allografting for patients with MM can result in long-term disease-free survival for a minority of patients. Efforts to reduce transplant-related mortality should focus on earlier transplantation, less toxic treatment regimens, better supportive care, and improved prevention and treatment of graft-versus-host disease (GVHD).

Increasingly, enriched populations of hematopoietic progenitors are used in experimental and clinical transplantation studies. The separation of progenitors is based on the expression of CD34, a marker preferentially expressed on progenitor cells. The dog model has been important for preclinical transplant studies, because it has proven predictive for outcomes in human hematopoietic stem cell transplantation. To identify and isolate canine hematopoietic progenitors, we have cloned a cDNA encoding a CD34 homologue from a canine myelomonocytic leukemia cell line, ML2. The CD34 homologue cDNA predicts an amino acid sequence that is highly conserved with human and murine CD34 in the cytoplasmic domain, transmembrane domain, and C-terminal end of the extracellular domain, but shows considerable divergence from these sequences at the amino-terminal end of the protein. In Western blotting studies, canine CD34 homologue (caCD34) appears to be a heavily and variably glycosylated protein with a molecular weight of approximately 100 kD and shows some tissue-specific differences in protein mass. To evaluate the expression of caCD34 protein, the extracellular domain of caCD34 was expressed as an Ig fusion protein and used as an immunogen to generate a rabbit polyclonal antiserum. The antiserum reacted against the fusion protein, against vascular endothelium, and with three leukemic cell lines. Approximately 1% of canine bone marrow cells stained brightly with antibodies to caCD34 and this population was 25- to 50-fold enriched for colony-forming units-granulocyte-macrophage as compared to unfractionated marrow mononuclear cells. These findings suggest that the canine CD34 homologue is expressed on bone marrow progenitor cells and, thus, that this molecule should be a valuable marker for identifying and isolating canine hematopoietic progenitors for experimental hematopoiesis and stem cell transplantation.

Acute graft-versus-host disease (GVHD) is most often treated with high dose glucocorticoids, but less than half of patients have durable overall improvement. Previous phase I and phase II studies suggested that treatment with a CD5-specific immunotoxin (XomaZyme-CD5 Plus) could ameliorate symptoms of GVHD. In a randomized, double-blind trial, we compared XomaZyme-CD5 Plus and glucocorticoids versus placebo and glucocorticoids as initial therapy for 243 patients who developed acute GVHD after allogeneic marrow transplantation. The study drug (XomaZyme. CD5-Plus or an identical appearing placebo) was administered at a dose of 0.1 mg/kg body weight on each of 14 consecutive days. All patients were treated concomitantly with a standard regimen of methylprednisolone. At the time of entry on study, 94% of patients had a rash, 56% had hyperbilirubinemia, 61% had diarrhea, and 84% had nausea and vomiting. At 3, 4, and 5 weeks after starting treatment, symptom severity was less in the CD5 group than in the placebo group. At 4 weeks, 40% of patients assigned to the CD5 group had complete response compared with 25% of those assigned to the control group (P = .019). At 6 weeks, 44% of patients assigned to the CD5 group had complete response as compared with 38% in the placebo group (P = .36). Clinical extensive chronic GVHD developed in 65% of patients in the CD5 group compared with 72% in the control group (P = .35). Survival at 1 year after treatment was 49% in the CD5 group and 45% in the control group (P = .68). Side effects required close monitoring and appropriate adjustment of treatment. The combined administration of a CD5-specific immunotoxin and glucocorticoids controls GVHD manifestations more effectively than treatment with glucocorticoids alone during the first 5 weeks after starting treatment. Use of this immunotoxin does not result in any long-term clinical benefit for patients with acute GVHD.