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Purpose: To compare the antitumor efficacy of three different anthracyclines in combination with cytarabine and etoposide in adult patients with newly diagnosed acute myeloid leukemia (AML)., Patients and Methods: We randomly assigned 2,157 patients (age range, 15 to 60 years) to receive intensive induction-consolidation chemotherapy containing either daunorubicin, idarubicin, or mitoxantrone. After achieving complete remission (CR), patients were assigned to undergo either allogeneic or autologous stem-cell transplantation (SCT), depending on the availability of a sibling donor., Results: The overall CR rate (69%) was similar in the three groups. Autologous SCT was performed in 37% of cases in the daunorubicin arm versus only 29% and 31% in mitoxantrone and idarubicin, respectively (P < .001). However, the disease-free survival (DFS) and survival from CR were significantly shorter in the daunorubicin arm: the 5-year DFS was 29% versus 37% and 37% in mitoxantrone and idarubicin, respectively. The proportion of patients who underwent allogeneic SCT (22%) was equivalent in the three treatment groups, and the outcome was similar as well. The [corrected] 5-year overall survival rates were 31%, 34%, and 34%, [corrected] respectively., Conclusion: In adult patients with AML who do not receive an allogeneic SCT, the use of mitoxantrone or idarubicin instead of daunorubicin enhances the long-term efficacy of chemotherapy.

Background and Objectives: The prognosis of elderly patients with acute myelogenous leukemia (AML) is usually dismal, while the true survival of older patients not included in clinical trials is not known. We retrospectively evaluated the impact on survival of an aggressive versus a non-aggressive approach in 1005 patients aged >60 years registered in the database of the GIMEMA cooperative group., Design and Methods: Group A patients (n=621) received aggressive treatment, while group B patients (n=384) underwent non-aggressive therapy. The groups were different for risk factor distribution: the patients in group B had a higher median age, worse performance status (PS) and a higher proportion of previous myelodysplastic disease., Results: The overall median survival was 7 and 5 months in groups A and B, respectively (p min of 0.0001). At multivariate analysis the following factors were associated with a significantly shorter survival: age >71 years (RR=1.27; 95% CI=1.07-1.50), PS=2-4 (RR=1.44; 95% CI=1.24-1.68), white cell count > 10,000 mL (RR=1.37; 95% CI=1.06-1.75), and heart dysfunction requiring treatment (RR=1.26; 95% CI=1.05-1.50). No difference in survival was associated with aggressive or non-aggressive treatment (RR=1.1; 95% CI=0.94-1.32). Patients aged min of 70 years, with no heart disease, but a white cell count > 10,000/mL showed a significantly better survival when treated aggressively (median survival 7 vs 3 months, p = 0.011)., Interpretation and Conclusions: Despite an obvious selection of patients with a worse prognosis in group B, the difference in survival between the two groups was marginal. Multivariate analysis failed to demonstrate a significant survival benefit in aggressively treated patients. All these considerations indicate that elderly patients with AML are overall unlikely to benefit from aggressive treatment, so that this should be offered only to selected patients.

The aim of the study was to evaluate the antileukemic effectiveness and toxicity of high-dose hydroxyurea (HHY) and to assess its acute toxicity. Between August 1997 and October 1998, 12 consecutive adult patients (>18 years) with high-risk acute myeloid leukemia (AML) (four patients in first early relapse, seven patients with secondary AML, and one patient with de novo AML concomitant to a lymphoproliferative disorder) were enrolled to receive a single course of HY (100 mg/kg per day) until bone marrow aplasia or for a maximum of 30 days. Of the 12 patients, 5 (41.6%) achieved complete remission (CR), 1 achieved partial remission (PR), 4 were resistant to treatment, and 2 died during induction from infection. No patient with relapsed AML achieved CR, while it was achieved by five of eight patients with secondary AML at diagnosis; five of six MDR1+ patients achieved CR. As concerns follow-up of the CR patients, one did not receive any further treatment and died in CR from pulmonary aspergillosis, and one with a concomitant chronic lymphocytic leukemia (CLL) received two courses of FLAG (fludarabine, cytarabine, granulocyte colony-stimulating factor) regimen with disappearance of the clonal Ig rearrangement, but relapsed after 11 months and died from pneumonia. The remaining three patients were consolidated with two courses of high-dose cytosine arabinoside (AraC), followed by peripheral blood stem cell transplantation (PBSCT) in one patient. One of them relapsed after 3 months, while the other two are still in continuous complete remission (CCR) after 16 and 28 months, respectively. This study has demonstrated the safety and efficacy of HHY in inducing CR in AML patients with unfavorable prognosis. Despite the small number of patients, these encouraging results warrant further studies.

Two cases of acute myeloid leukaemia (AML) with CD2 and CD7 expression associated with diabetes insipidus (DI) as the initial symptom are presented. Both patients had t(3;3)(q21;q26) associated with monosomy 7 and EVI-1 overexpression. No neurohypophysis infiltration was evident. One patient died during induction chemotherapy, the other did not respond to therapy and died with persistent DI. Our findings further support the existence of a distinct AML entity characterized by the presence of DI, abnormalities of chromosome 3q, dysmegakaryopoiesis and poor outcome, and provide evidence of EVI-1 gene involvement. The possible role of chromosome 3q26 abnormalities in determining this peculiar clinical-biological association is emphasized.

We studied the impact of cytogenetics and kind of induction/consolidation therapy on 848 adult acute myeloid leukemia (AML) patients (age 15-83). The patients received three types of induction/consolidation regimen: standard (daunorubicin and cytosine arabinoside (3/7); two cycles); intensive (idarubicin, cytosine arabinoside and etoposide (ICE), plus mitoxantrone and intermediate-dose Ara-C (NOVIA)); and low-dose (low-dose cytosine arabinoside). CR patients under 60 years of age, if an HLA-identical donor was available received allogeneic stem cell transplantation (allo-SCT); otherwise, as part of the program, they underwent autologous (auto)-SCT. CR rates significantly associated with 'favorable' (inv(16), t(8;21)), 'intermediate' ('no abnormality', abn(11q23), +8, del(7q)) and 'unfavorable' (del (5q), -7, abn(3)(q21q26), t(6;9), 'complex' (more than three unrelated cytogenetic abnormalities)) karyotypes (88% vs 65% vs 36%, respectively; P = 0.0001). These trends were confirmed in all age groups. On therapeutic grounds, intensive induction did not determine significant increases of CR rates in any of the considered groups, with respect to standard induction. Low-dose induction was associated with significantly lower CR rates. Considering disease-free survival (DFS), multivariate analysis of the factors examined (including karyotype grouping) showed that only age > 60 years significantly affected outcome. However, in cases where intensive induction was adopted, 'favorable' karyotype was significantly related to longer DFS (P = 0.04). This was mainly due to the favorable outcome of t(8;21) patients treated with intensive induction. Patients receiving allo-SCT had significantly longer DFS (P = 0.005); in particular, allo-SCT significantly improved DFS in the 'favorable' and 'intermediate' groups (P = 0.04 and P = 0.048, respectively). In conclusion our study could provide some guidelines for AML therapy: (1) patients in the 'favorable' karyotype group seem to have a longer DFS when treated with an intensive induction/consolidation regimen, adopted before auto-SCT instead of standard induction; this underlines the importance of reinforcement of chemotherapy, not necessarily based on repeated high-dose AraC cycles. Allo-SCT, independently of induction/consolidation therapy, should be considered an alternative treatment; (2) patients in the 'intermediate' karyotype group should receive allo-SCT; (3) patients in the 'unfavorable' karyotype group should be treated using investigational chemotherapy, considering that even allo-SCT cannot provide a significantly longer DFS, but only a trend to a better prognosis.

Purpose: Neutropenic enterocolitis (NE) is a severe complication of intensive chemotherapy and is barely identifiable by clinical signs alone. Ultrasonography (US) supports the diagnosis of NE by showing pathologic thickening of the bowel wall. The aim of this study was to evaluate the prognostic value of the degree of mural thickening evaluated by US in patients with clinically suspected NE., Patients and Methods: Neutropenic patients with fever, diarrhea, and abdominal pain after intensive chemotherapy for hematologic malignancies were studied with abdominal US. We evaluated the degree of bowel wall thickening detected by US and its correlation with the duration of the clinical syndrome as well as NE-related mortality., Results: Eighty-eight (6%) of 1,450 consecutive patients treated for leukemia had clinical signs of NE. In 44 (50%) of 88 patients, US revealed pathologic wall thickening (mean +/- SD, 10.2 +/- 2.9 mm; range, 6 to 18). The mean duration of symptoms was significantly longer in this group (7.9 days) than among patients without mural thickening (3.8 days, P <.0001), and the NE-related mortality rate was higher (29.5% v 0%, P <.001). Patients with bowel wall thickness of more than 10 mm had a significantly higher mortality rate (60%) than did those with bowel wall thickness < or = 10 mm (4.2%, P <.001)., Conclusion: Symptomatic patients with sonographically detected bowel wall thickening have a poor prognosis compared with patients without this finding. In addition, mural thickness of more than 10 mm is associated with poorer outcome among patients with NE.

The occurrence of acute myeloid leukemia (AML) as a secondary tumor has been frequently reported in patients who received various chemotherapy regimens for hematologic malignancies wile the concomitant development of chronic lymphoproliferative diseases (CLD) and AML in previously untreated patients is extremely rare. We report a case with an apparently spontaneous occurrence of AML and non Hodgkin low-grade lymphoma diagnosed by immunological, cytogenetical and molecular analyses. In particular genetic studies allowed to identify the coexistence of a clonal lymphoid population and a myeloid blast component characterized by inv(16) marker and CBFbeta-MYH11 gene fusion. Complete remission of AML and the CLD was obtained following high doses of hydroxyurea and two consolidation cycles of fludarabine plus intermediate dose cytarabine.

Objective: To evaluate in a multicenter retrospective study, the clinical and laboratory characteristics and the outcome of patients with acute myeloid leukemia (sAML) previously diagnosed with breast cancer (BC) among an adult acute leukemia population., Patients and Methods: Between June 1992 and July 1996, 3934 new cases of adults with acute leukemia were recorded in GIMEMA Archive of Adult Acute Leukemia (2964 AML, 901 ALL, 69 acute leukemia expressing both myeloid and lymphoid surface markers)., Results: Two hundred patients (5.1%) presented with a history of previous malignancy (21 of them were affected by ALL and 179 by AML). Among sAML, 37 patients (29%) had a previous breast cancer. They consisted of 36 females and 1 male, median age 56 years, range 34-87. The median latency between the 2 malignancies was 54 months (range 5-379). Twenty-seven patients received chemo- and/or radiotherapy for breast cancer (7 only chemotherapy, 6 only radiotherapy, and 14 combined treatment). All patients were surgically treated but in 10 patients surgical debridement was the sole therapy for breast cancer. The drugs most frequently employed were alkylating agents (18 patients), topoisomerase II inhibitors (9 patients), antimetabolites (20 patients) (CMF, CEF and MMM combinations). At onset of sAML the median WBC count was 7.7 x 10(9)/l (0.8-153) and the median platelet count was 33.5 x 10(9)/l (3-305). Considering morphological features, FAB subtypes were 4 M0, 5 M1, 11 M2, 5 M3, 8 M4, 3 M5, and 1 M6. Cytogenetic study was performed on 28 patients and 12 of them presented abnormalities. It is noteworthy that chromosome 5 or 7 abnormalities (typically observed in those patients treated with alkylating agents) were present only in three cases. Thirty-four patients received chemotherapy for sAML, and twenty-five of them achieved a CR (74%), with a median duration of twenty-eight weeks (5-280+). The overall survival was 8 months (1-80+)., Discussion: The high number of sAML we observed in patients with a previous breast cancer, may be due to the fact that this malignancy is the most frequent neoplasm in women and by the high probability of cure with a consequent long disease-free survival. Our results suggest that the risk of sAML after recovery from breast cancer is increasing due to the rise in the number of patients cured from breast cancer, and in the future could be a relevant problem for haematologists.

Granulocytic sarcoma (GS) is a rare extramedullary tumor composed of immature myeloid cells. It is usually associated with leukemia or other myeloproliferative disorders, but can also occur without overt hematologic disease, i.e. in patients with a normal bone marrow and no history of acute myelogenous leukemia. This primary extramedullary lesion may indeed represent a diagnostic and therapeutic dilemma for both the hematopathologist and oncologist. We describe a case of GS diagnosed in a nonleukemic patient and review the literature regarding the pathologic features and treatment of this condition., (Copyright 2000 S. Karger AG, Basel)

The c-mpl ligand, thrombopoietin (TPO), is a physiologic regulator of platelet and megakaryocytic production, acting synergistically on thrombopoiesis with the growth factors interleukin 11 (IL-11), stem cell factor, interleukin 3 (IL-3), interleukin 6 (IL-6), and granulocyte-macrophage colony-stimulating factor. Because some of these growth factors, especially TPO and IL-11, are now being evaluated clinically to reduce chemotherapy-associated thrombocytopenia in cancer patients, we evaluated 25 acute myeloid leukemia (AML) samples to test whether TPO, IL-11, and other early-acting megakaryocyte growth factors can affect leukemic cell proliferation, cell cycle activation, and programmed cell death (PCD) protection. TPO induced proliferation in the majority of AML samples from an overall mean proportion of S-phase cells of 7.8% +/-1.5% to 14.5% +/- 2.1% (p = 0.0006). Concurrent G0 cell depletion was found in 47.3% of AML samples. TPO-supported leukemic cell precursor (CFU-L) proliferation was reported in 5 of 17 (29.4%) of the samples with a mean colony number of 21.4 +/- 9.6 x 10(5) cells plated. In 13 of 19 samples, a significant protection from PCD (from an overall mean value of 13% +/-0.7% to 8.8% +/- 1.8%;p = 0.05) was detected after TPO exposure. Conversely, IL-11-induced cell cycle changes (recruitment from G0 to S phase) were detected in only 2 of 14 samples (14.2%). In addition, IL-11 showed little, if any, effect on CFU-L growth (mean colony number = 17.5 9.5) or apoptosis. Combination of TPO with IL-11 resulted in only a slight increase in the number of CFU-L, whereas IL-3 and stem cell factor significantly raised the mean colony numbers up to 119.2 +/- 68.3 and 52.9 +/- 22.1 x 10(5) cells plated, respectively. We conclude that TPO induces cell cycle activation in a significant proportion of cases and generally protects the majority of AML blast cells from PCD. On the other hand, IL-11 has little effect on the cell cycle or PCD. Combination of both TPO and IL-11 is rarely synergistic in stimulating AML clonogenic growth. These findings may be useful for designing clinical studies aimed at reducing chemotherapy-associated thrombocytopenia in AML patients.

Changes in plasma-free amino acid (PFAA) concentrations in the presence of solid tumors have been widely described. Conversely, the PFAA profile in patients with acute leukemias is less well defined. The aim of the present study was to clarify whether the PFAA profile is altered in patients with acute myeloid leukemia (AML), whether the profile differs from the PFAA profile of solid tumors, and whether it may predict outcome of AML. Fasting PFAA were measured in 40 untreated, normally nourished patients with AML (17 males, 23 females), ages 22-78 y, with white blood cell (WBC) counts ranging from 1.08 to 276.5 x 10(3)/cm2, and in 24 healthy volunteers. Plasma concentrations (mu mol/L, mean +/- SE) of glutamic acid (GLU), free tryptophan (FTRP), ornithine (ORN), and glycine (GLY) were significantly higher in AML (GLU: 90.2 +/- 6.1 versus 37 +/- 8; FTRP: 7.0 +/- 0.6 versus 4.8 +/- 0.3, P < 0.005; ORN: 108.7 +/- 5.8 versus 78 +/- 6, P < 0.001; GLY: 295.0 +/- 14.8 versus 239 +/- 9, P < 0.01), whereas serine (SER), methionine (MET), and taurine (TAU) were significantly lower in AML than in controls (SER: 109.0 +/- 5.8 versus 130 +/- 4, P < 0.03; MET: 25.5 +/- 1.3 versus 33 +/- 3, P < 0.03; TAU: 46.5 +/- 3.5 versus 81 +/- 2, P < 0.001), and tended to be even lower in patients who had not responded to chemotherapy or had relapsed within 18 mo of enrollment. Such changes were unrelated to age, sex, and WBC count. Changes in PFAA that occur in AML are only in part similar to those observed in solid tumors. The reduction of TAU appears to be a typical feature of AML and might be secondary to the deficiency of its precursors SER and MET. Further studies are under way aimed at clarifying whether PFAA might predict prognosis in AML, whether PFAA is normalized by remission induction, and if its correction may be of any benefit for patients with hematologic malignancies.

Background and Objective: The successful use of differentiating treatment for patients with acute promyelocytic leukemia (APL) suggests that other acute myeloid leukemias (AML) may benefit from tailored and subtype-specific therapy. Despite the fact that new drugs specifically targeting AML genetic lesions have not yet been developed, distinct karyotypic categories have been identified which may deserve differentiated treatment. In addition, molecular assays to assess response to therapy more sensitively are now available for several AML subsets. In this review, we discuss the role of genetic characterization in the therapy of AML, and the investigative efforts which we believe are still needed for the design of tailored treatment for each and every patient with this disease., Design and Methods: The authors have been working in this field for many years and have contributed original papers, the data of which are incorporated in this article. In addition, the material analyzed in this overview includes articles and reviews covered by the Science Citation Index and Medline as well as some more recent unpublished personal observations., Results: Modern therapeutic approaches to AML tend to differentiate post-induction treatment intensity according to cytogenetically defined risk categories. Such prognostic categorization is largely unsatisfactory. In fact, following the advent of newly developed molecular assays (e.g. RT-PCR and FISH), specific and prognostically relevant lesions are frequently found in patients with an apparently normal karyotype, and these patients are, therefore, re-assigned to more appropriate prognostic categories. In addition, recent studies suggest that some patients may benefit from an increase in induction intensity; rapid genetic characterization will be needed for future differentiation of initial therapy. However, preliminary investigation of AML by integrated karyotypic/molecular analyses show that no specific abnormalities are detectable in at least half of the cases. Therefore, use of genetic criteria for prognostic stratification is currently feasible in only a proportion of patients., Interpretations and Conclusions: The prognostic role of genetic lesions, currently identified by karyotypic studies, needs to be validated in large series of AML patients prospectively characterized by advanced molecular/cytogenetic analyses and treated uniformly. In addition, searches for new clinically relevant genetic abnormalities, and diagnostic tools for their rapid identification are urgently needed to identify prognostic categories better. Elucidation of AML gene alterations should foster basic investigation aimed at developing new drugs targeted to the specific lesion in the individual patient. Before these more specific therapeutic agents are developed, diagnostic genetic characterization should add to other well-established prognostic factors to optimize the use of the presently available therapies.

Thirty-eight patients with primary resistant or relapsing acute myeloid leukemia (AML) were treated with fludarabine, cytarabine and granulocyte colony-stimulating factor (FLAG). Median age was 41 (range 11-70). Sixteen patients had AML that was primary resistant to induction treatment, while 22 were relapsed, 11 after autologous bone marrow transplant (AuBMT), 8 less than 6 months from complete remission (CR) achievement, and 3 were second relapse from chemotherapy alone. Overall, 21 of 38 patients (55%) obtained CR. Age, sex, length of CR, and interval between autoBMT and FLAG administration did not significantly influence the CR rate. On the contrary, a normal karyotype at diagnosis was significantly related to a better outcome. There were 4 induction deaths (10%), due to fungal infection in 2 patients and hemorrhagic complications in the remaining two. All patients experienced profound cytopenia. Median time to neutrophil (>500/microl) recovery was 21 days, while a platelet count >20,000/microl was reached after 23 days. The median period of hospitalization was 31 days. The nonhematological toxicity was mild, mainly consisting of mucositis. There were 17 documented infections and 17 episodes of fever of unknown origin. Following CR achievement, 6 patients received autoBMT, 3 alloBMT, 2 high-dose arabinosil-cytosine, and 2 are on a waiting list for transplantation procedure. We conclude that FLAG is an effective and well-tolerated regimen for refractory or recurrent AML, mainly useful for patients to be admitted to bone marrow transplantation.

The outcome of a cohort of 218 consecutive patients who failed to respond to a single course of standard daunorubicin plus ARAC (three + seven) induction regimen has been retrospectively evaluated to assess the characteristics of this group of AML patients and the effectiveness of second-line induction programs. Seventy-four of the 218 patients (33.9%) attained complete remission with salvage chemotherapies. The multivariate analysis of pretherapy characteristics of the patients showed that peroxidase positivity and age were the most important factors in determining whether or not the patient would have a favorable response to second-line induction regimen. In addition, comparison of marrow characteristics at diagnosis with those of marrow after the first-line therapy (marrow leukemic index, MLI) provided the greatest differences between second-line CR and resistant patients. Finally, peroxidase positivity and MLI predicted for remission duration and overall survival. Allogeneic BMT, however, appeared the most important factor for survival and event-free survival of remitting patients. These results are of importance when considering that better defined prognostic factors provide an objective rationale for selecting appropriate strategies for the treatment of patients who do not respond to a single course of induction regimen.

Thirty-one patients with either advanced AML (18) or blastic CML (13) were treated with an intensive timed sequential combination of VP-16 (100 mg/m2/day i.v., days 1-3 and 8-10), intermediate-dose Ara-C (500 mg/m2 i.v. over 1 h q 12 h, days 1-3 and 8-10) and carboplatin (150 mg/m2/day i.v. continuous infusion, days 1-3 and 8-10). CR rates were 9/18 (50%) for patients with AML and 9/13 (69%) for those with blastic CML, for an overall CR rate of 58%. Among patients with AML, CR rates for specific subgroups were: primary resistant disease 2/6; resistant relapse 1/5; second relapse 6/7. Ten patients were refractory to VAC and three (10%) died of complications during marrow hypoplasia. Median overall survival was 7 months, and median DFS of the 18 responders 4 months. The major toxicity was myelosuppression and infection. The VAC regimen has significant activity and acceptable toxicity in myelogenous leukemias. The very high response rate observed in blastic CML warrants further testing of carboplatin-based regimens in this poor-risk form of leukemia.

Fourteen poor risk acute myeloid leukemia (AML) patients were treated with G-CSF prior (from day 0) and during chemotherapy with fludarabine and Ara-C from day 1 to day 5 (the FLAG regimen). Several biological parameters were monitored on the blast population: multidrug resistance (MDR) functional expression by rhodamine-123 efflux (Rhd-E), cell cycle changes, induction of apoptosis and leukemic clonogenic cell growth (CFU-L). The mean basal Rhd-E value was 14.4% (range 0-51.2), and 12/14 patients exhibited a dye efflux > 4%, efficiently blocked by the MDR-reversal agent cyclosporin A. After 24 h of G-CSF administration, cell cycle studies showed in bone marrow (BM) samples a significant mean increase in S phase (p = 0.04) and in RNA content of G1 cells (p = 0.01), coupled to a significant increase in apoptosis (p = 0.02). Clonogenic cell growth analysis showed a twofold increase in BM CFU-L in 6 of the 14 cases tested. When G-CSF activity was assessed without the addition of exogenous growth factors (autonomous proliferation), a significant increase (p = 0.02) in CFU-L was found only in patients who achieved a complete remission (CR); these patients were also characterized by lower S-phase values at diagnosis. Eight of the 14 patients treated achieved CR, but the median response duration was three months, and only two cases are still in CR. The FLAG regimen can thus induce remission in poor risk AML patients. The responses, however, are short, suggesting that resistant cells are not efficiently affected by either the use of agents not involved in the MDR-efflux mechanism or by the G-CSF priming strategy. Other post-induction therapies need to be considered in further approaches.

Several studies have demonstrated that G-CSF, GM-CSF and, in particular, IL-3 can effectively recruit acute myeloid leukaemia (AML) blasts into the cell cycle, resulting in a significant increase in cytosine-arabinoside (Ara-C) mediated cytotoxicity in vitro. Since IL-3 has shown biological and clinical activity, we investigated the cell kinetic effects of rIL-3 and high-dose Ara-C/idarubicin in three patients with refractory AML selected for the presence of chromosome 7 monosomy; this enabled differentiation between the effects of IL-3 on leukaemic and on normal cells. The in vivo administration of rhIL-3 (250 micrograms/m2d s.c. for 6-10d) recruited AML blasts into the cell cycle in two of the three patients, and this effect resulted in an increase in in vitro growth of clonogenic cells (CFU-L) and of their S-phase fraction. The percentage of leukaemic cells with monosomy 7 increased only in the two cases who showed a proliferative response. Normal cells were not recruited, even when rhIL-3 was administered for up to 10 d. In vitro studies showed an increased Ara-C cytotoxicity on clonogenic AML cells, in particular with IL-3 plus GM-CSF, thus confirming the priming effects of IL-3 in the two responding cases. The results of this study suggest that rhIL-3 can selectively recruit leukaemic cells into the cell cycle. Although leukaemic blasts can be sensitized to Ara-C, other mechanisms of primary blast resistance may limit the clinical benefit of kinetic-based approaches.

5-Aza-2'-deoxycytidine (Decitabine) is an analog of deoxycytidine now entering clinical trials in acute myeloid leukemia (AML) owing to a defined antileukemic activity mediated at least in part by DNA hypomethylation, altered gene expression, and induction of cell differentiation. In the present study, we examined the relationship between the in vitro sensitivity to Decitabine of blast progenitors and the clinical outcome, in nine AML patients treated in vivo with Decitabine within a phase II trial carried out at two different institutions. Leukemic blast progenitors in acute myeloid leukemia (AML) undergo terminal divisions giving rise to colonies in methylcellulose. The self-renewal capacity of blast progenitors is conversely reflected by a secondary methylcellulose assay after exponential growth of clonogenic cells in suspension cultures. Three out of four patients, in which clonogenic cells in methylcellulose were strongly suppressed by Decitabine and clonogenic growth of blasts cultured in suspension was only slightly affected, failed on Decitabine treatment in vivo. Two subjects, whose blast progenitors in suspension culture were significantly inhibited by Decitabine, obtained a positive hematological response (complete or partial remission, CR or PR) and an additional patient showing a similar in vitro pattern died in induction with an hypoplastic marrow without morphological evidence of persistant leukemia. Interestingly two patients displaying an unfavourable in vitro pattern (i.e. a minor suppression of self-renewal mitoses as evinced from suspension cultures) achieved a hematological response (CR and PR) upon in vivo therapy with Decitabine. The in vitro response to Decitabine of clonogenic progenitors from both these patients shifted to a favourable pattern (i.e. major suppression of self-renewal versus terminal mitoses) following manipulation of culture conditions by the addition or removal of exogenous growth factors. In addition, in a further patient refractory to treatment with Decitabine in vivo, similar alterations of the culture conditions were unable to modify the unfavourable pattern of response to the drug in vitro. Our results indicate that the sensitivity of blast progenitors in suspension cultures strongly correlates with the remission outcome of the patients. From our data, it also appears that alterations of culture microenvironment are able to modify the response of AML blasts to Decitabine, unveiling the 'hidden' sensitivity of leukemic progenitors to the drug in cases characterized by a discrepancy between in vivo and in vitro results, i.e. apparent in vitro resistance and favourable clinical outcome.

Granulocyte-macrophage colony-stimulating factor, (GM-CSF) was given at 8 micrograms/kg daily by continuous i.v. infusion for 72 h to six patients with acute myeloid leukemia (AML) in expansion and one with chronic myeloid leukemia in blastic crisis to determine whether it was possible to augment the proliferative activity of the neoplastic population. The percentage of marrow blasts in S phase (labeling index, LI) was increased in five patients (1.3-, 1.5-, 1.9-, 2.3- and 3.2-fold change). The increase in LI was similar 24 and 48 h after beginning GM-CSF. The RNA Index also increased in patients who showed an increased LI, suggesting that GM-CSF had recruited quiescent neoplastic cells into the cell cycle. Forty eight hours after beginning GM-CSF, chemotherapy was started. The fate of S phase cells, labeled in vivo with bromodeoxyuridine (BrdU) immediately before cytostatic treatment, was monitored. BrdU positive cells were identified by fluorescent antibody for up to 28 days. A preferential killing of BrdU (S phase) cells was observed in 5/7 patients who obtained a complete remission, whereas this was not apparent in the two patients who achieved only a partial remission. Chemotherapy induced a rapid and profound aplasia; its duration, however, was not significantly different from that observed in historical controls. GM-CSF may have a potential role in the treatment of AML, as this study shows that it recruits leukemic cells into the cell cycle without adversely prolonging aplasia after cycle-specific therapy.