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Incidence and prognostic value of respiratory events in acute leukemia

Acute respiratory failure and infectious pneumonia are the major causes of death during induction chemotherapy of acute leukemia. However, the causes, incidence and prognostic value of all respiratory events (REs) occurring in this context have never been assessed prospectively. We recruited 65 consecutive patients with newly diagnosed acute leukemia into a 1-year prospective study (December 2000–November 2001) to evaluate the incidence and prognostic value of these events. REs were frequent: 38 were recorded in 30 patients. There was a significant relationship between REs and pre-existing respiratory disease and/or smoking. REs were caused by infection in 34% of cases, by an established cause other than infection in 42% and had an undetermined cause in 24%. Poor early outcome (death within 45 days of starting induction chemotherapy) in patients experiencing an RE was independently associated with a >25/min respiratory rate (P=0.003) and the nonachievement of complete remission (CR) (P<0.0001). Predictors of overall survival in the entire patient population were the absence of CR (P<0.0001), REs (P=0.02) and a ⩾2 performance status (P=0.03). In conclusion, REs are frequent during induction chemotherapy of acute leukemia and represent an independent prognostic factor of poor outcome, regardless of their cause.

Multicentric evaluation of the MDR phenotype in leukemia

The wide discrepancies in the frequency of ‘positive’ samples for multidrug resistance (MDR) phenotype within the same type of tumor observed in the literature justified the need for the definition of consensus recommendations. To define standard techniques of MDR phenotype measurement, we ran a large multicentric evaluation of the different methods available. Thirty-six French centers participated in the study, and 742 samples of 2–10 × 106 viable cells were sent by overnight express mail between December 1993 and February 1996. The same batches of MRK16, 4E3 and UIC2 were used. Nineteen samples of leukemia (12 AML, 1 ALL, 6 lymphoproliferative syndromes) and six leukemic cell lines with different levels of MDR expression were tested. Five meetings reached agreement concerning the guidelines for each technique, except immunocytochemistry. The 19 fresh samples were tested by each center using one to four techniques among cytofluorometry, immunocytochemistry, functional tests and RT-PCR. Five samples were diagnosed as ‘negative’ according to local criteria, with few discordant results (0 to 16% of ‘positive’ results). For all the 14 remaining samples, large discrepancies were observed from center to center, and from one technique to another. No correlations could be found between techniques. Flow cytometric analysis of cells already exposed to MRK16 or control IgG2A, fixed in paraformaldehyde and sent to centers did not reduce the discrepancies between centers in two of the four samples with moderate expression, emphasizing the role of histogram interpretation. The use of alternative monoclonal antibodies (4E3 and UIC2) did not reduce the discrepancies observed. In a second step, the K562 parental cell line, a low resistant subline (K562/HHT100, ×7 resistance index to DNR) and a high resistant subline (K562/HHT300, ×125 resistance index to DNR) were sent blindly three times, with an increasing level of recommendations for flow cytometry. Dramatic improvements were observed in cytometric results when the result was expressed as the ratio of arithmetic mean of fluorescence of antibody (10 μg of MRK16)/arithmetic mean of fluorescence of control (10 μ g IgG2A): the proportion of expected results increased from 61 to 100% for K562, and from 37 to 85% for K562/HHT100. For uptake and drug efflux measurements, the use of 1 h uptake of 0.1μ M of rhodamine, followed by 1 h efflux ±10 μ M of verapamil, permitted an increased reproducibility of the technique from 71 to 100% for K562 and K562/HHT100. Whatever the technique used, concordant results were obtained for K562/HHT300. The immunocytochemistry, using several antibodies (MRK16, JSB1 and C219) gave many non-interpretable results (44%), due to a frequent high background and discordant results between antibodies in the same centers, and discordant conclusions between centers. The group does not recommend this technique for circulating tumoral cells.

Functional assay of multidrug resistant cells using JC-1, a carbocyanine fluorescent probe

Multidrug resistance (MDR) is characterized by a decrease in the efficiency of chemotherapeutic agents correlated with the expression and activity of a membrane protein: the permeability-glycoprotein (Pgp 170). Clinically, detection of MDR can be performed by functional tests based on the accumulation of fluorescent compounds such as rhodamine 123. With the aim of improving the sensitivity of such analysis, we have evaluated JC-1, a fluorescent lipophilic carbocyanine dye. Above a critical concentration, JC-1 aggregates in a ‘liquid crystal’ form. Aggregates display a specific red emission band centered at 597 nm whereas the monomers display a green emission band centered at 540 nm. JC-1 was avidly accumulated in sensitive K562 cells where it displayed both a green cytoplasmic and red mitochondrial fluorescence. In contrast, JC-1 was poorly accumulated in resistant K562 cells, which displayed only a slight green fluorescence. The level of JC-1 accumulation was correlated with the level of Pgp expression detected by MRK16 and UIC2 antibodies on a set of K562 subclones with increasing resistance levels. The specific fluorescence properties of JC-1 allow accurate discrimination between low-level resistant cells and sensitive cells. Chemosensitizers such as verapamil, cyclosporine A or S9788 restored JC-1 accumulation in resistant cells. The fluorescence properties of JC-1 could therefore be used for monitoring the effects of reversing agents.

Role of MRP1 in multidrug resistance in acute myeloid leukemia.

The best characterized resistance mechanism in adult acute myeloid leukemia (AML) is the one mediated by the MDR1 gene which has been shown to be associated with poor outcome. However, alternative proteins such as the more recently recognized multidrug-associated protein (MRP1), may also contribute to the resistance to anthracyclines and etoposide in AML. Recently, the role of this protein was discussed and was unclear in AML. However, recent data concerning the functionality and the modulation of the activity of MRP1 may elucidate its role in comparison with other mechanisms of resistance. In this paper, we will review these recent data concerning the role of MRP1 in adult AML.

Is BAL useful in patients with acute myeloid leukemia admitted in ICU for severe respiratory complications

In patients with hematological malignancy (HM) developing acute respiratory failure (ARF) bronchoalveolar lavage (BAL) is considered as a major diagnostic tool. However, the benefit/risk ratio of this invasive procedure is probably lower in the subset of patients with acute myeloid leukemia (AML). The study was to analyze the yield of BAL performed in HM patients (n=175) with AML or lymphoid malignancies (LM) admitted in intensive care unit (ICU) for ARF and pulmonary infiltrates. BAL was performed in 121 patients (53/73 AML patients (73%) and 68/102 LM patients (67%)) without a definite diagnosis at admission or contraindication for fiberoptic bronchoscopy. Life-threatening complications were noticed in 12/121 patients (10%). The overall diagnostic yield of BAL was 47% (25/53) in AML patients and 50% (34/68) in LM patients. A microorganism was recovered from BAL in 23% (12/53) of AML patients and 41% (28/68) of LM patients (P<0.005). BAL results induced significant therapeutic changes in 17% (9/53) of AML patients vs 35% (24/68) of LM patients (P=0.039). This study underlines the rather low diagnostic yield of BAL for infectious diagnosis and the low rate of therapeutic changes induced by its results in AML patients with ARF admitted in ICU.

Lung resistance protein (LRP) gene expression in adult acute myeloid leukemia: a critical evaluation by three techniques

The role of LRP in clinical drug resistance in acute myeloid leukemia (AML) is controversial. We therefore compared multiple assays, including RT-PCR, immunocytochemistry (ICC) and flow cytometry (FC), in 10 cell lines and in 47 fresh and thawed AML cells in order to validate and to quantitate measures for LRP phenotype detection. We also compared different ways of expressing the results. Lastly, in cell lines, we analyzed the 50% lethal concentration (LC50), by MTT assay, of cisplatin which could estimate the functionality of LRP. The reproducibility of LRP detection measured by RT-PCR, ICC and FC was good. In the same way, within the same technique, there was good correlation between the different methods of expressing the results of LRP level. Therefore, the discrepancies noted with the three techniques used were neither a problem of reproducibility nor a problem of results expression. On the other hand, there was only a correlation between ICC and FC, and no correlation between RT-PCR and LRP protein detection techniques. Therefore, RT-PCR is probably not the optimal technique for LRP detection. We have shown in 10 cell lines a higher correlation between FC and LC50 of cisplatin than between ICC and LC50 of cisplatin and no correlation between RT-PCR and LC50 of cisplatin. For five patients, there was a dissociation between ICC and FC. Four patients were positive by FC and negative by ICC and only one patient was negative by FC and positive by ICC. Therefore, if in vitro resistance to cisplatin represents the functionality of LRP, we recommend the use of FC rather than ICC to detect LRP expression. Besides the measurement of LRP as a diagnostic tool in the evaluation of resistance to chemotherapy in patients with AML, we urgently need to establish a functional test in order to assess LRP activity.

Effect of the multidrug inhibitor GG918 on drug sensitivity of human leukemic cells

The drug GG918 has been specifically developed for overcoming MDR phenotype and is now in use in clinical trials. In this study, the effects of GG918 on leukemic cell were investigated using a 3 day MTT assay. Results showed that, in a highly resistant P-gp(+) leukemic cell line, 0.1 μ M of GG918 gives rise to a 40-fold sensitization to daunorubicin (DNR) (residual resistance: 2.1), a 57-fold sensitization to mitoxantrone (residual resistance: 1.5), and a 3.3-fold sensitization to idarubicin (residual resistance: 2.9). When human AB serum was added to the incubation medium, 1 μ M GG918 was needed to observe the full P-gp modulation potency described above. The effect of 1 μ M of GG918 was tested on 27 samples of poor prognosis acute leukemia (25 AML, two ALL). DNR sensitization (using the MTT assay) and modulation of rhodamine 123 uptake were monitored and used as criteria for comparing the in vitro modulation potency of this new compound to the potency of 10 μ M of verapamil, which was used as reference. A good correlation (r = 0.8, P = 0.001) was observed between the results of the two tests. Eleven out of the 26 cases tested were MDR1 (+) (42%), and showed a higher IC50 for DNR than the negative cases (861 ± 1284 n Mvs 187 + 246 n M, P = 0.05). GG918 was able to modulate the in vitro resistance to DNR in eight cases (seven MDR1(+), no MDR1(−), one non-tested). Verapamil did not increase DNR toxicity in four of these eight cases, but was more efficient in one other MDR1(+) case. In conclusion, the DNR sensitivity of the majority of the fresh AML samples expressing P-gp could be modulated in vitro by 1 μ M of GG918.

Both P-gp and MRP contribute to drug resistance in AML

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