Naohi Sahara

Clinicopathological and prognostic characteristics of CD56‐negative multiple myeloma

Summary. We analysed CD56 expression in 70 patients with multiple myeloma (MM) to determine its clinicopathological and prognostic significance. Fifty‐five (79%) patients were CD56+. CD56– patients (n = 15) had higher β2 microglobulin levels and a higher incidence of extramedullary disease, Bence Jones protein, renal insufficiency and thrombocytopenia than CD56+ patients. Their myelomas more frequently had a plasmablastic morphology. Overall survival was significantly lower in CD56– than CD56+ patients (22 vs 63 months, P = 0·0002). We conclude that CD56– MM is a discrete entity associated with more aggressive disease. The higher incidence of plasmablastic cases suggested that CD56– MM may develop from a less mature plasma cell than CD56+ MM.

Arsenic trioxide therapy in relapsed or refractory Japanese patients with acute promyelocytic leukemia: updated outcomes of the phase II study and postremission therapies.

Recently, arsenic trioxide (ATO) has been proved to induce complete remission (CR) at a high rate in patients with acute promyelocytic leukemia (APL).We prospectively investigated the safety and efficacy of ATO therapy in patients with relapsed and refractory APL and examined the duration of CR and the postremission therapies. Initially, 0.15 mg/kg ATO was administered until bone marrow remission to a maximum of 60 days. After the patient achieved CR, 1 additional ATO course at the same dosage was administered for 25 days. Of 34 patients, 31 (91%) achieved CR. PML-RARα messenger RNA was not detected in the bone marrow of 18 (72%) of the 25 patients evaluated by reverse transcriptase—polymerase chain reaction analysis. At a median follow-up of 30 months, the estimated 2-year overall survival rate was 56%, and the estimated 2-year event-free survival rate was 17%. During the ATO therapy, QTc prolongation was observed in most cases. Fifteen patients developed ventricular tachycardia, and 1 of them showed torsades de pointes. Other adverse events were nausea, water retention, APL differentiation syndrome, skin eruption, liver dysfunction, and peripheral neuropathy, all of which were quite tolerable. ATO therapy was remarkably effective for relapsed APL; however, postremission therapies were necessary to maintain a durable remission.

Arsenic trioxide therapy for relapsed or refractory Japanese patients with acute promyelocytic leukemia: need for careful electrocardiogram monitoring.

Recent studies have shown that arsenic trioxide (As2O3) can induce complete remission in patients with acute promyelocytic leukemia (APL). We tested the efficacy and safety of As2O3 for the treatment of patients with APL who had relapsed from or become refractory to all-trans retinoic acid (ATRA) and conventional chemotherapy in a prospective study. As2O3 at a dose of 0.15 mg/kg was administered until the date of bone marrow remission to a maximum of 60 days. In patients who achieved complete remission (CR), one additional course of As2O3 was administered using the same dose for 25 days. Of 14 patients, 11 (78%) achieved CR. Six of 10 patients who achieved CR showed disappearance of PML-RARα transcript by RT-PCR assay. The duration of As2O3-induced CR ranged from 4 to 22 months (median, 8 months) at a median follow-up of 17 months. Adverse events included 13 electrocardiogram abnormalities (13 QTc prolongation, eight ventricular premature contraction, four nonsustained ventricular tachycardia and two paroxysmal supraventricular tachycardia), seven nausea and vomiting, four pruritus, three peripheral neuropathy, three fluid retention and one APL differentiation syndrome. Four patients received antiarrhythmic agents. Hyperleukocytosis developed in five patients and in three cytotoxic drugs were necessary. Other adverse events were relatively mild. As2O3 treatment is effective and relatively safe in relapsed or refectory patients with APL. Cardiac toxicities in patients with QTc prolongation should be carefully monitored.

Efficacy of gemtuzumab ozogamicin on ATRA- and arsenic-resistant acute promyelocytic leukemia (APL) cells

Acute promyelocytic leukemia (APL) cells express a considerable level of CD33, which is a target of gemtuzumab ozogamicin (GO), and a significantly lower level of P-glycoprotein (P-gp). In this study, we examined whether GO was effective on all-trans retinoic acid (ATRA)- or arsenic trioxide (ATO)-resistant APL cells. Cells used were an APL cell line in which P-gp was undetectable (NB4), ATRA-resistant NB4 (NB4/RA), NB4 and NB4/RA that had been transfected with MDR-1 cDNA (NB4/MDR and NB4/RA/MDR, respectively), ATO-resistant NB4 (NB4/As) and blast cells from eight patients with clinically ATRA-resistant APL including two patients with ATRA- and ATO-resistant APL. The efficacy of GO was analyzed by 3H-thymidine incorporation, the dye exclusion test and cell cycle distribution. GO suppressed the growth of NB4, NB4/RA and NB4/As cells in a dose-dependent manner. GO increased the percentage of hypodiploid cells significantly in NB4, NB4/RA and NB4/As cells, and by a limited degree in NB4/MDR and NB4/RA/MDR cells. Similar results were obtained using blast cells from the patients with APL. GO is effective against ATRA- or ATO-resistant APL cells that do not express P-gp, and the mechanism of resistance to GO is not related to the mechanism of resistance to ATRA or ATO in APL cells.

Prognostic Significance of Surface Markers Expressed in Multiple Myeloma: CD56 and Other Antigens

Multiple myeloma (MM) is characterized by increased numbers of malignant plasma cells. Plasma cells, that represent the terminal differentiation of B lymphocytes, have considerable heterogeneity of surface markers expressed on them. Some studies showed the prognostic significance of several immunophenotypic molecules on MM cells. Here, we review several surface markers related to their prognostic significance in MM patients. We also report that CD56-negative MM is the unique entity characterized by poor prognosis with high incidence of extramedullary disease, Bence Jones protein, renal insufficiency, thrombocytopenia and plasmablastic morphology.

Two cases of acute promyelocytic leukemia complicated by torsade de pointes during arsenic trioxide therapy

We describe 2 patients with acute promyelocytic leukemia (APL) in whom torsade de pointes (TdP) developed during treatment with arsenic trioxide. Patient 1 was a 23-year-old woman with second-relapse APL. Ventricular premature beat bigeminy developed on day 27 of treatment, and episodes of TdP developed on day 28. Patient 2 was a 51-year-old woman with second-relapse APL who had cardiomyopathy due to prior anthracycline treatment. TdP developed on day 17 of treatment. Arsenic trioxide is known to cause electrocardiographic abnormalities, such as ventricular tachycardia and prolongation of QT interval. Patient 1 was given fluconazole as a concomitant drug. Patient 2 had cardiomyopathy and hypokalemia. Careful management is needed during arsenic trioxide therapy because this treatment prolongs the QT interval, possibly inducing episodes of TdP.

Etodolac inhibits EBER expression and induces Bcl‐2‐regulated apoptosis in Burkitt's lymphoma cells

Abstract:  Cyclooxygenase‐2 (COX‐2) is reported to be an important cellular target for therapy in malignancies. The growth inhibitory effects of COX‐2 inhibitors on malignancies have been demonstrated to be through not only COX‐2 dependent, but also independent mechanisms. In this study, we showed that etodolac, COX‐2 inhibitor, induced apoptosis via COX‐2 independent pathway, and investigated the molecular details of etodolac‐induced apoptosis in Burkitts lymphoma cells. In Daudi and Raji Burkitts lymphoma cell lines, which expressed no COX‐2 enzyme, etodolac more strongly induced apoptosis compared to meloxicam. Moreover, etodolac did not induce apoptosis to normal B‐lymphocytes. For the pathway of etodolac‐induced apoptosis, reduction of anti‐apoptotic bcl‐2 mRNA and Bcl‐2 protein, activation of Caspase‐9 and ‐3, down‐regulation of caspase inhibitors, c‐IAP‐1 and Survivin were involved. Moreover, EBER‐1 and ‐2 expression in Epstein–Barr virus positive Daudi and Raji cells were reduced to result in down‐regulation of Bcl‐2 by treatment with etodolac. It has been reported that etodolac has stereoisomers, R‐ and S‐etodolac. We found that racemate of etodolac more strongly induced apoptosis in Daudi and Raji cells compared to R‐ or S‐etodolac. In conclusion, our findings indicated etodolac inhibited EBERs expression and induced apoptosis via a Bcl‐2‐regulated pathway. Moreover, racemate of etodolac more effectively induced apoptosis than R‐ and/or S‐etodolac. Therefore, these activities of etodolac potentially extend to the treatment of patients with Burkitts lymphoma resistant to chemotherapy.

Phenylarsine oxide (PAO) more intensely induces apoptosis in acute promyelocytic leukemia and As2O3-resistant APL cell lines than As2O3 by activating the mitochondrial pathway.

We studied the cytotoxic effect of an organic arsenical compound, phenylarsine oxide (PAO) on an acute promyelocytic leukemia (APL) cell line (NB4) and an As2O3-resistant NB4 subline (NB4/As). Cell growth was inhibited by 50% (IC50) upon 2-day treatment with As2O3 or PAO at 0.54 and 0.06 μM, respectively in NB4 cells (P = 0.025), and 2.80 and 0.08 μM, respectively in NB4/As (P = 0.030). 0.1 μM PAO increased the proportion of hypodiploid cells (50.3%) by a greater degree than the same dose of As2O3 (3.8%) in NB4 cells. In NB4 cells, 0.1 μM PAO reduced the mitochondrial transmembrane potential (20.5% in a PInegative-Rhodamine123low fraction) by a greater degree than 1 μM As2O3 (7.1%). Western blotting showed that 0.1 μM PAO downregulated the expression of both Bcl-2 and Bcl-XL proteins, whereas I μM As2O3 downregulated only Bcl-2 expression. These results suggest that the cytotoxic effect of PAO on an APL cell line and As2O3-resistant subline is significantly higher than that of As2O3. PAO-induced apoptosis seems to be related to the activation of the mitochondrial pathway and downregulation of both Bcl-2 and Bcl-XL. PAO is a considerable agent for relapsed/refractory APL and for purging APL cells following stem cell transplantation.

Clinicopathological and prognostic characteristics of CD33-positive multiple myeloma.

Abstract:  There have been few reports about the CD33 expression on multiple myeloma (MM) cells so far, showing that only a few patients expressed CD33 homogenously on their MM cells. However, in these reports, neither detailed clinical information nor its prognostic significance was described. Therefore, we analyzed the CD33 expression on MM cells from 63 newly diagnosed patients by flow cytometry and the correlation with other clinical parameters to determine the clinicopathological significance of this molecule. Fourteen (22%) patients were positive for CD33. Of the 14 patients with CD33+ MM, >80% of MM cells were positive in six (9.5%). The CD33+ patients had higher β2 microglobulin and lactate dehydrogenase levels and higher incidence of anemia and thrombocytopenia than did CD33− patients. The estimated 3‐yr overall survival in CD33+ patients was significantly lower than in the CD33− ones (31% and 50%, respectively, P = 0.042). Especially, mortality within a year from diagnosis in the CD33+patients was higher than that in CD33− patients (43% and 10%, respectively, P = 0.005). Serial evaluation of CD33 expression showed that the amount of CD33 significantly increased after a variety of treatment including melphalan and steroid in individual patients. These results suggest that the CD33 expression might be associated with drug resistance to these conventional agents, and CD33 might be a useful target for the development of new therapeutic agents in MM.

Two Patients with All-trans Retinoic Acid-Resistant Acute Promyelocytic Leukemia Treated Successfully with Gemtuzumab Ozogamicin as a Single Agent

Acute promyelocytic leukemia (APL) cells express a considerable level of CD33, which is the target of gemtuzumab ozogamicin (GO), and a significantly lower level of P-glycoprotein (P-gp). Therefore, GO is predicted to be a successful treatment for APL. In this article, we report on the GO treatment of 2 patients with APL, who had fully relapsed after induction therapy with all -trans retinoic acid (ATRA) following chemotherapy. Both patients had relapsed 3 times and were resistant to reinduction therapy with ATRA. GO (9 mg/m2) was administered on days 1 and 15. After GO treatment, both patients achieved complete hematologic and molecular remission. GO may be another promising agent for the treatment of ATRA-resistant relapsed APL when given as salvage chemotherapy.