Real-time PCR analysis of PML-RARα in newly diagnosed acute promyelocytic leukaemia patients treated with arsenic trioxide as a front-line therapy

BACKGROUND

Recently, patients with acute promyelocytic leukaemia (APL) have experienced significant clinical gains after treatment with arsenic trioxide. However, the use of this agent as a front-line therapy for newly diagnosed patients is unclear.

PATIENTS AND METHODS

Of 95 newly diagnosed APL patients, 85 patients who achieved complete remission (CR) were sequentially evaluated during a 4-60 month period by conventional RT-PCR. A total of 30 patients (six relapsed and 24 in continued CR) were selected and monitored by quantitative real-time PCR (RQ-PCR) assay. The PML-RARalpha fusion transcripts values were normalised to every 10(6) copies of G6PDH transcripts (NQ).

RESULTS

RQ-PCR analyses showed a rapid rate of clearance of NQ levels during the courses of arsenic therapy. In the majority of patients in CR, the NQ levels were below 5 x 10(2) in peripheral blood (PB) samples. In all the relapsed cases with follow-up intervals of 1-6 months (median 3 months) clinical relapse was predictable by increasing NQ level above this threshold.

CONCLUSIONS

Our study highlights the usefulness of PB and the definition of threshold level for early prediction of relapse. The threshold level correlates well with risk of relapse; therefore, transcript ratio below the level should be regarded as a goal in the clinical management of this disease.

Measurement of multidrug resistance in acute leukemia with three methods (Pgp expression, dnr accumulation & rho accumulation)

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Background: Multidrug resistance (MDR) is one of the most important causes of treatment failure in chemotherapy specially in acute leukemias. One of the MDR resistance mechanisms is mdr1 gene expression that causes P-glycoprotein (Pgp) expression on cell surface. Its expression and function is detected by flowcytometry. we decided to measure its expression by three method in our leukemias patients. Then we studied correlation of each of these tests with relapse, resistance, survival and some other parameters. Methods: before chemotherapy bone marrow. Pgp expression was detected with MRK16 Ab. For interpreting of Pgp we use D-value. D-value >0.15 was considered positive for Pgp. For dnr accumulation & rho accumulation D-value >0.2 was considered positive. Informations was colleced from patient chart. Correlation of OS, DFS, resistance to therapy with Pgp expression by each method was studied. Results: there were 84 patients (52 male & 32 female). 18 cases of ALL & 66 cases of AML were included. Mean age was 30 ± 13 and mean of follow up was 168 ± 106 days. Mean of dPgp was 0.35 ± 0.05, mean of ddnr was 0. 5 ± 0.28 and mean of drho was 0. 5 ± 0.28 too. There was significant correlation between patients presented with first relapse and dPgp (p-value < 0.009).But there was not true for ddnr or drho.Sensitivity and specifity of Pgp for resistance to therapy was 35% & 75% respectively. Sensitivity and specifity of dnr accumulation for resistance to therapy was 11% & 76% respectively. Sensitivity and specifity of Pgp for resistance to therapy was 11% & 76% respectively. There is on significant correlation between Pgp and OS. It was true for dnr accumulation & rho accumulation. RFS was longer for patients with negative Pgp, but there was not significant correlation. In patients with positive Pgp probability of relapse was 9 times more than negative Pgp. Conclusions: among these three tests Pgp expression is more useful for predicting resistance to therapy. There is no difference between dnr accumulation and rho accumulation in detecting resistance to therapy. But sensitivity of Pgp expression in detecting resistance to therapy is more than the two other tests. We can use Pgp expression as a helpful test for recognizing more resistant disease.

No significant financial relationships to disclose.

Quantitative analysis of PML-RARα in newly diagnosed acute promyelocytic leukemia patients treated with arsenic trioxide as a front-line therapy

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Background: Recently, patients with acute promyelocytic leukemia (APL) have experienced significant clinical gains after treatment with arsenic trioxide (As2O3). However, the potential role for use of this agent as a front-line therapy for newly diagnosed patients is unclear. Methods: From 95 patients with APL, 85 patients who achieved complete remission (CR) were sequentially evaluated during 4–60 months period of follow-up by conventional RT-PCR. A total of 30 patients (6 relapsed and 24 in continued long remission) were selected and monitored by quantitative real-time PCR (RQ-PCR) assay. Using ‘Hybridization Probes‘ technology, the expression of PML-RARα/G6PDH transcript ratio was analyzed in serial PB samples taken at different courses of disease and the results were compared with the clinical outcome. Results: More than 90% of patients obtained molecular remission, as determined by conventional RT-PCR in 1–3 months after start of arsenic therapy. RQ-PCR analyses showed a rapid rate of clearance of PML-RARα/G6PDH transcript level during the courses of arsenic therapy. In majority of the patients in CR the level of PML-RARα/ G6PDH ratio was always below 5×102 in PB samples. In all the relapsed cases with follow-up intervals of 1–6 months (median 3) clinical relapse was predictable by increasing transcript level above this threshold. Conclusions: Using a sensitive and quantitative method provided valuable information about effectiveness of arsenic as a front-line therapy in the management of newly diagnosed APL. Our study highlights the usefulness of PB and the definition of threshold level for early prediction of relapse. The threshold level correlates well with relapse risk; therefore, transcript ratio below the level should be regarded as a goal in the clinical management of this disease.

No significant financial relationships to disclose.

The effect of cryopreservation on clonogenic capacity and in vitro expansion potential of umbilical cord blood progenitor cells

BACKGROUND

Umbilical cord blood progenitor cells have been demonstrated to possess significant advantages over bone marrow in terms of proliferative capacity and immunologic reactivity. But the low number of hematopoeitic stem cells (HSC) is the most important limitation of its use. The ex vivo expansion of cord blood progenitor cells is the current strategy to overcome this problem. Furthermore, among the factors that enable successful cord blood transplantation is the ability to store and subsequently recover a sufficient number of viable cells. Since it would be costly to expand umbilical cord blood (UCB) progenitor cells, it is important to determine the feasibility and reproducibility of progenitor cell expansion after cryopreservation. We evaluated whether cryopreservation procedures might impair the clonogenic capacity and in vitro expansion of UCB.

MATERIALS AND METHODS

We evaluated the cell viability, clonogenic capacity, CD34+38- content and in vitro expansion potential of progenitor cells from UCB (n = 10) separated mononuclear cells (MNC), before and after 1 month of cryopreservation by programmed rate freezing.

RESULTS

Although cell viability decreased after cryopreservation (P < .05), there was no significant difference in CD34+ or CD34+38- absolute count, colonogenic capacity and in vitro expansion potential of cord blood progenitor cells (P > .05).

CONCLUSIONS

Since the survival of CD34+ cells was greater than other elements, CD34+ cells seem more tolerant to cryopreservation than the other nucleated populations. Moreover in vitro expansion of UCB progenitor cells may be obtained following cryopreservation. Our results suggest that cryopreservation procedures do not impair the clonogenic capacity and in vitro expansion potential of cord blood stem/progenitor cells.

Treatment of acute promyelocytic leukemia with arsenic trioxide without ATRA and/or chemotherapy

INTRODUCTION

Arsenic trioxide is effective and approved for treatment of relapsed or refractory acute promyelocytic leukemia (APL) cases resistant to all-trans retinoic acid (ATRA), but its effect on new cases of APL is not clear.

MATERIALS AND METHODS

We studied 111 patients with APL. Arsenic trioxide was infused at 0.15 mg/kg daily dose, until complete remission was achieved. Then, after 28 days of rest, arsenic trioxide was infused daily for 28 days as consolidation therapy. We studied minimal residual disease (MRD) by semi-sensitive reverse transcription polymerase chain reaction (RT-PCR) on peripheral blood samples.

RESULTS

Complete remission was observed in 95 patients (85.6%). With the median (range) follow-up period of 16.5 (1-57) months, 1- and 2-year disease-free survival was 88.3% and 63.7%, respectively; 24 patients relapsed, 19 of whom achieved a second complete remission, again by arsenic trioxide. Third and fourth remissions were seen in some relapsed patients, again by arsenic trioxide. For patients in complete remission, 1- and 3-year survival was 95.5% and 87.6%, respectively. MRD was positive in four (8.3%) out of 48 cases during 1 year after remission induction; three of them relapsed clinically.

CONCLUSIONS

Arsenic trioxide is effective as first-line treatment for APL. Results of arsenic trioxide combination therapy with chemotherapy/ATRA requires further study.

Are HLA antigens a risk factor for acute GVHD in thalassemic patients receiving HLA-identical stem cell transplantation?

We retrospectively evaluated the association between risk factors and acute graft-versus-host disease (aGVHD) among 182 beta thalassemia patients who received 73 peripheral blood stem cell (PBSC) or 109 bone marrow transplants from HLA-identical siblings between 1991 and 2003. The relationship between the severity of aGVHD was examined for the following factors: HLA antigens, age, sex, ABO mismatch, sex mismatch (between recipient and donor), thalassemia class, graft source, transplant cell dose, CD3+ cell dose, conditioning regimen, GVHD prophylaxis, neutrophil engraftment duration, and blood product transfusions using univariate and multivariate analyses. Overall 61 (34%) patients developed clinical grade III or grade IV aGVHD. Univariate analysis confirmed an increased risk of severe aGVHD, which was associated with HLA-A11, HLA-A26, and PBSCT (P=.04, .03, and .03, respectively). The risk of aGVHD was reduced in the presence of HLA-A3 (P=.03). Multivariate analysis confirmed the increased risk of aGVHD associated with HLA-A11 (P=.04), HLA-A26 (P=.01), and a short-period neutrophil recovery (P=.009). In this study HLA-A11, HLA-A26, PBSCT, and a short neutrophil engraftment period were probable risk factors and HLA-A3 a probable protective factor associated with severe aGVHD. These data may provide useful guidelines to choose strategies for treatment and prevention.