[Increased response rate with rituximab in relapsed and refractory follicular and mantle cell lymphomas -- results of a prospective randomized study of the German Low-Grade Lymphoma Study Group]

BACKGROUND AND OBJECTIVE

Rituximab has shown a high activity in relapsed follicular lymphomas when given alone. Further on, phase-II-studies indicate that its addition to chemotherapy may improve the response rate substantially. However, so far, prospective randomized studies have not been available.

PATIENTS AND METHODS

In 1998 the GLSG started a multicenter trial in patients with relapsed or refractory indolent lymphoma or mantle cell lymphoma. A fludarabine-containing regimen (FCM) was chosen for salvage therapy, with fludarabine 25 mg/m(2)/d 1-3, cyclophosphamide 200 mg/m(2) d 1-3 and mitoxantrone 8 mg/m(2) d 1. A total of four courses, every 4 weeks were given. Patients were prospectively randomized for FCM alone or the immunochemotherapy with R-FCM (375 mg/m(2) one day before FCM) RESULTS: About 147 randomized patients 93 had follicular, 40 mantle cell and 14 lymphoplasmocytic/-cytoid lymphoma. Statistical analysis was performed by sequential testing and indicated for 94 fully evaluable patients a significant advantage for the R-FCM-arm, with an overall response rate of 83 % as compared to 58%, when treated with FCM alone (CR: 35 % vs. 13 %). Similar improvements of remission rate were detected in the different lymphoma subgroups, especially in MCL (OR: 65 % vs. 33 %). Both treatment options were associated with hematological toxicities of grade III and IV, but well tolerated; infectious complications were rare, with no difference between the two treatment groups.

CONCLUSION

This prospectively randomized trial demonstrates for the first time a significant improvement of the combined immunochemotherapy related to the remission rate in patients with relapsed or refractory indolent lymphoma.

Efficacy of fludarabine, intermittent sequential high-dose cytosine arabinoside, and mitoxantrone (FIS-HAM) salvage therapy in highly resistant acute leukemias

Patients with refractory acute leukemias after intensive induction and salvage attempts have a particularly poor prognosis and therapeutic options are limited. In the current study, the pharmacologically based FIS-HAM regimen was applied, which included fludarabine 15 mg/m2 q 12 h (days 1, 2, 8, and 9), cytosine arabinoside as a 45-min infusion every 3 h at 750 mg/m2 per single application (days 1, 2, 8, and 9), and mitoxantrone 10 mg/m2 (days 3, 4, 10, 11). Twenty-six intensively pretreated patients [median age: 38 years; range: 22-65; 16 cases of acute myeloid leukemia (AML) and 10 of acute lymphoblastic leukemia (ALL)] were included. Of 16 patients with AML, 5 achieved a complete remission (CR, 31%), 1 a partial remission (PR, 6%), 2 were nonresponders (13%), and 8 succumbed to early death (ED, 50%). Of 10 patients with ALL, 5 achieved a CR, 1 a PR, 1 was a nonresponder, and 3 died early. Overall, the CR rate was 38%. The median disease-free survival time was 50 days and median survival 90 days. Two patients underwent allogeneic bone marrow transplantation and are alive after 27 and 28 months. Neutropenia amounted to a median of 46 days. Toxicity WHO III/IV included infection (61%), diarrhea (48%), nausea/vomiting (43%), impairment of heart function (30%), and mucositis (26%). The current data indicate a significant activity of FIS-HAM chemotherapy in advanced acute leukemias. However, due to its pronounced toxicity, this regimen should be restricted to third-line therapy for patients expecting a suitable donor for allogeneic transplantation, and supportive treatment should be optimized.

IDEC-C2B8 (Rituximab) anti-CD20 antibody treatment in relapsed advanced-stage follicular lymphomas: results of a phase-II study of the German Low-Grade Lymphoma Study Group

PURPOSE

The current study was initiated to assess the clinical efficacy and side effects of rituximab in patients with relapsed advanced stage follicular lymphoma.

PATIENTS AND METHODS

The study was performed as an open-label non-randomized multicenter phase-II trial and included patients older than 18 years of age with relapsed advanced-stage follicular lymphomas (FL) grades I and II, according to the REAL classification, or with centroblastic/centrocytic (CB/CC lymphomas according to the Kiel classification. Four weekly doses of 375 mg/m2 rituximab were applied.

RESULTS

38 patients from eight centers were included between January 1997 and January 1998 and were evaluable for response and toxicity on an intention to treat basis. The median age was 55 years (range 26-75 years). Thirteen patients (35%) were in first relapse, 11 patients (30%) in second, and 13 patients (35%) in third relapse. The median time between primary diagnosis and study entry was 4.6 years (range 0.9-14.7 years). Twenty-three patients tolerated the application of rituximab without adverse events; in 13 cases the infusion rate had to be reduced because of side effects; in two patients the application was stopped because of pharyngeal edema and anaphylactoid reaction. The most frequent side effects were fever (13 patients) and rigor (13 patients); 65% of the side effects were observed after the first infusion. Twenty grade-III/IV side effects were considered to be related to treatment: lymphocytopenia (3), granalocytopenia (1), thrombocytopenia (2), fever (1), hyperglycermia (1), venous thrombosis (1), syncope (1), plasmatic coagulation disorder (1), shortness of breath (2), photosensitivity (1), cardiac failure (1), chills (1), sepsis (1), tumor lysis (1), anemia (1), and pharyngeal edema (1). Eight patients were not eligible for assessment of response because of non-follicular subtypes of low-grade lymphomas (n =6) or early termination of therapy at the first infusion because of severe side effects (n =2). From the 30 evaluable cases with follicular lymphomas, five patients achieved a complete remission (CR) (17%), nine patients a partial remission (PR) (30%), and two patients a minor response (MR) (7%). The overall response rate was 47%. The median time to treatment progression (TTP) was 201 days (range 64-293 days), with five patients experiencing long-lasting remissions of 214-293 days duration. In three patients, the rituximab-induced remission exceeded the preceding progression-free interval substantially. Bulky disease (P=0.058) and/or bone-mar row involvement (P=0.046) were associated with poor response.

CONCLUSION

This study confirms the moderate treatment-related toxicity and the high antilymphoma activity of rituximab in patients with relapsed follicular lymphoma. Further studies are needed to determine the role of rituximab in the first-line treatment of these disorders and its combination with conventional chemotherapy.

Successful modulation of high-dose cytosine arabinoside metabolism in acute myeloid leukaemia by haematopoietic growth factors: no effect of ribonucleotide reductase inhibitors fludarabine and gemcitabine

High-dose cytosine arabinoside (AraC)-containing regimens have shown the highest antileukaemic efficacy of all currently used regimens in the treatment of acute myeloid leukaemia (AML). This study aimed at increasing the antileukaemic potential of high-dose AraC by raising intracellular levels of AraC triphosphate (AraCTP), which is the mediator of cytotoxicity, via biochemical modulation by inhibitors of ribonucleotide reductase (RR) or haematopoietic growth factors (HGFs). Blasts from patients with de novo AML were analysed for their formation of AraCTP under high-dose AraC conditions (20 microM over 3 h) without prior modulation (n = 47) after a 2-h pre-exposure with fludarabine (50 microg/ml) (n = 40) or gemcitabine (30 ng/ml) (n = 40) and after a 48-h pre-exposure to granulocyte colony-stimulating-factor (G-CSF; 100 ng/ml) (n = 27) or granulocyte-macrophage colony-stimulating-factor (GM-CSF; 100 U/ml) (n = 28). Unmodulated formation of AraCTP (median 239.8 ng/107 cells) could not be increased via modulation by gemcitabine (232.4 ng/107 cells) or fludarabine (247.8 ng/107 cells). The lack of effect of RR inhibitors was also observed for all other known metabolites of AraC [Ara-cytosine monophosphate (CMP), Ara-cytosine diphosphate (CDP), AraCDP-choline, Ara-uridine monophosphate (UMP), Ara-uridine diphosphate (UDP) and Ara-uridine triphosphate (UTP)]. In contrast, pre-exposure to HGFs led to significant increases in AraCTP formation (G-CSF 556.0 ng/107 cells, 2.31-fold increase, P < 0.001; GM-CSF 447.9 ng/107 cells, 1.87-fold increase, P < 0.0001). To establish the mechanism responsible for these effects, the activity of the rate-limiting enzyme of AraC metabolism, deoxycytidine kinase (dCK), was investigated (n = 33). In vivo exposure to GM-CSF led to increases in dCK activity from unmodulated values at 0 h (29.8 pmol/min/mg protein) to 34.3 pmol/min/mg protein at 24 h (1.15-fold increase) and 54.5 pmol/min/mg protein at 48 h (1. 83-fold increase). The raise in dCK activity over 48 h was significant (P < 0.013).

Recent advances in antigen-targeted therapy in non-Hodgkin's lymphoma

Substantial advances in antigen-targeted lymphoma therapy have been achieved in recent years that make the use of monoclonal antibodies a highly attractive concept and promise further improvements in the clinical management of malignant lymphoma. The development of the chimeric anti-CD20 antibody IDEC-C2B8 (Rituximab) proved the concept of an effective therapy with a single unconjugated monoclonal antibody in lymphoma patients. Radioimmunoconjugates with myeloablative activity induced response rates of 80-100% in heavily pretreated patients. Progress in the genetic engineering of immunotoxins has improved the efficacy of these constructs. Ongoing prospective clinical trials will define the optimal use of these innovative therapeutic agents in patients with malignant lymphoma, and may establish therapeutic strategies with a high anti-lymphoma specificity and a low unspecific toxicity.

Impact of the simultaneous administration of the (+)- and (-)-forms of formyl-tetrahydrofolic acid on plasma and intracellular pharmacokinetics of (-)-tetrahydrofolic acid

PURPOSE

To detect possible interactions between (-)-formyl-tetrahydrofolic acid (leucovorin, (-)-fTHF) and (+)-formyl-tetrahydrofolic acid ((+)-fTHF) on the plasma and intracellular pharmacokinetics following their simultaneous administration.

METHODS

Plasma levels of (-)-fTHF, (-)-methyl-THF, and (+)-fTHF were determined in samples from four volunteers following the administration of both (-)-fTHF and (+/-)-fTHF and in seven patients during a 5-fluorouracil (5-FU)/fTHF combination chemotherapy. In addition, the intracellular uptake of (14)C-(-)-mTHF in the presence of (+)-mTHF at increasing concentrations was measured in vitro. Analyses were performed using a highly specific high-performance liquid chromatography procedure.

RESULTS

The pharmacokinetic parameters obtained for (-)-fTHF following the administration of (-)-fTHF only were: terminal half-life, 1.2 h; area under the curve, 10 microg. h/ml; maximum concentration, 12 microg/ml; clearance, 305 ml/min; volume of distribution, 19 l. The parameters did not differ significantly as compared with those obtained following the administration of (+/-)-fTHF to both volunteers and patients. There were no differences in the pharmacokinetics of (-)-mTHF or in the protein binding of both substances with the different forms of administration. The intracellular uptake of (14)C-(-)-mTHF did not depend on the presence of (+)-mTHF at either concentration.

CONCLUSIONS

These data suggest that (-)-fTHF is not therapeutically superior to (+/-)-fTHF and that the latter is appropriate during combination chemotherapy with 5-FU/fTHF in patients with colorectal cancers.

Multivariate analysis of prognostic factors in patients with refractory and relapsed acute myeloid leukemia undergoing sequential high-dose cytosine arabinoside and mitoxantrone (S-HAM) salvage therapy: relevance of cytogenetic abnormalities

To improve the basis for the stratification of patients with refractory and relapsed acute myeloid leukemia (AML) univariate and multivariate analyses of prognostic factors were performed in 254 patients (median age 50 years, range 18-74) undergoing S-HAM salvage chemotherapy during two consecutive prospective trials of the German AML Cooperative Group. In a multivariate analysis, duration of the first complete remission (CR) was the only factor associated with time to treatment failure (P = 0.0223). Disease-free survival was influenced by a short duration of the first CR of less than 6 months (P = 0.0001), WBC (P = 0.0018), blast count (P = 0.0037), and neutrophil count (P = 0.0119). The achievement of CR was related to the hemoglobin level only (P = 0.0457), the early death rate was related to age only (P = 0.0109), and survival was related to the bilirubin level only (P = 0.0166). In the subgroup of 104 patients in whom additional karyotype analyses were performed prior to first-line therapy unfavorable chromosome abnormalities were associated with a lower CR rate (univariate analysis, P = 0.0342; CR 24% vs 53%) and were the only factor related to survival. These analyses warrant the further evaluation of the impact of cytogenetic abnormalities on the outcome of patients with advanced AML in order to improve the characterization according to duration of first CR and to WBC of distinct subgroups of patients with differing prognoses as a basis for stratification in future trials.

Hypercoagulability in a patient with hypodysfibrinogenemia: implications for clinical management

Dysfibrinogenemia accounts for approximately 0.7% of thrombophilia in patients with venous thromboembolic disease. In 20% of these patients, plasma thrombophilic dysfibrinogen is below 1.0 mg/ml, defining hypodysfibrinogenemia. We describe a young female patient, in whom hypodysfibrinogenemia was the cause of several severe thromboembolic events which occurred even under oral anticoagulation monitored by a standard prothrombin time (PT) test. In this patient, the standard PT test according to Quick underestimated the plasma coagulability in vivo, presumably due to the low levels of dysfunctional fibrinogen as the substrate of the thromboplastin reagent. A PT test supplemented with bovine plasma fibrinogen (Thrombotest) revealed lower fibrinogen-independent international normalized ratio (INR) values in the proposita on oral anticoagulation compared to a control group with eufibrinogenemia. Monitoring therapy with the fibrinogen-independent Thrombotest secured safe anticoagulation in this patient. We suggest to consider PT tests with exogenous fibrinogen (e.g. Thrombotest) to monitor oral anticoagulation in the rare thrombophilic patients with hypodysfibrinogenemia.

Monoclonal antibody therapy for B cell non-Hodgkin's lymphomas: emerging concepts of a tumour-targeted strategy

Although much progress has been made in the understanding of the pathobiology of malignant lymphomas in recent years, progress in the treatment of patients with this diagnosis has been limited. Monoclonal antibody therapy is an innovative and promising concept in the treatment of malignant lymphoma, and the current status of this treatment is reviewed here. Phase I/II clinical trials have proven the high antilymphoma activity of antibody-based therapeutic strategies. Radioimmunoconjugates with myeloablative activity have induced response rates of between 80 and 100% in heavily pretreated patients. The chimeric monoclonal antibody IDEC-C2B8 has shown high antilymphoma activity in patients with relapsed follicular lymphoma with an overall response rate of up to 50%. The combination of the IDEC-C2B8 antibody with standard chemotherapy has shown encouraging results with no increase in toxicity compared with chemotherapy alone. The introduction of antibody therapy promises to open new perspectives in the treatment of patients with malignant lymphoma. Prospective randomised clinical trials will define the patient who will gain maximal benefit from antibody-based therapy.

Activated protein C resistance and factor V Leiden in patients with hemolysis, elevated liver enzymes, low platelets syndrome

OBJECTIVE

Hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome is characterized by a distinct activation of the coagulation system. A mutation of the gene coding for coagulation Factor V (Factor V Leiden) has been identified as the most frequent risk factor for thrombosis. To identify risk factors for HELLP syndrome, we determined coagulation parameters and the Factor V Leiden mutation in women who previously had developed HELLP syndrome.

METHODS

Coagulation parameters (activated protein C resistance, antithrombin, protein C, protein S) were determined in 21 women 6 months to 9 years after they had developed HELLP syndrome in the third trimester. In addition, these women were analyzed for the presence of the Factor V Leiden mutation.

RESULTS

Of these analyzed women, 33% (seven of 21) had an activated protein C resistance (activated protein C ratio less than 2.0). Another 38% of the women had subnormal activated protein C ratios (2.0-2.3). Only 57% of the women with an activated protein C resistance were identified as heterozygous carriers of the Factor V Leiden mutation (four of seven).

CONCLUSION

Women with HELLP syndrome have a higher incidence of Factor V Leiden mutations. This increased incidence does not, however, account fully for the increased frequency of activated protein C resistance in these patients.

Interferon alfa for the treatment of follicular lymphomas

PURPOSE

Recombinant human interferon alfa (rIFN-alpha) has demonstrated significant activity against follicular lymphomas when applied as salvage treatment after the failure of conventional therapy. It has also been shown to exhibit synergistic antitumor activity when given simultaneously with certain cytostatic agents.

PATIENTS AND METHODS

Against this background, two major strategies were followed to incorporate rIFN-alpha into the first-line treatment of follicular lymphomas: application simultaneously with initial cytotoxic chemotherapy and application as maintenance treatment after successful initial chemotherapy.

RESULTS

Of the five prospective randomized trials performed to assess the activity of rIFN-alpha in combination with initial chemotherapy versus the activity of chemotherapy alone, three studies showed that rIFN-alpha plus chemotherapy yielded no beneficial effect on remission rate, remission duration, or overall survival. In all three of these trials, chemotherapy consisted of a single alkylating agent. In contrast, a significant improvement in remission rate and remission duration was observed in two studies when rIFN-alpha was combined with anthracycline-containing regimens. Five prospective randomized studies have evaluated the role of rIFN-alpha as maintenance therapy after successful cytoreductive chemotherapy. Four of these studies have either found no significant prolongation of the disease-free interval or shown significant improvement in disease-free survival only in patients achieving a complete remission with initial cytoreductive treatment. In all four studies, relatively low doses of rIFN-alpha were administered for a limited time. A different outcome emerged in the fifth study, by the German Low Grade Lymphoma Study Group, in which patients received higher doses of rIFN-alpha with no restriction on duration of therapy. Patients treated with rIFN-alpha had a significantly prolonged median progression-free interval (30 versus 19 months), and at 4 years, 45% of patients receiving rIFN-alpha maintenance therapy remained relapse-free, compared with 26% of patients in the untreated control group (P = 0.003).

CONCLUSION

Collectively, these data demonstrate that rIFN-alpha adds substantially to the treatment of follicular lymphomas either when combined with anthracycline-containing cytoreductive chemotherapy or when given as long-term maintenance therapy.

Mantle-cell lymphomas have more widespread disease and a slower response to chemotherapy compared with follicle-center lymphomas: results of a prospective comparative analysis of the German Low-Grade Lymphoma Study Group

PURPOSE

To compare mantle-cell lymphomas (MCLs) and follicle-center lymphomas (FCLs) for their features of clinical presentation, response to chemotherapy, and prognosis on the basis of a prospective randomized clinical trial.

PATIENTS AND METHODS

Patients with MCL and FCL who entered onto the prospective randomized comparison of cyclophosphamide, vincristine, and prednisone (COP) versus prednimustine and mitoxantrone (PmM) followed by a second randomization for interferon (IFN) maintenance versus observation only.

RESULTS

One hundred sixty-five of 234 patients had FCL and 45 of 234 patients had MCL. With FCL, both sexes were equally affected (men, 47%); patients with MCL were predominantly men (78%; P < .0004) and had a higher median age (64 v 53 years; P < .0001). Patients with MCL also had more widespread disease, reflected by the proportion of patients with two or greater extranodal manifestations (43% v 21%; P < .005) and nine or greater involved nodal areas (64% v 45%; nonsignificant [NS]). Response to chemotherapy was significantly lower in patients with MCL (complete remission [CR] + partial remission [PR], 69% v 88%; P < .05) and occurred at a slower pace. Patients with MCL also had a shorter event-free interval (median, 8 v 24 months; P < .0001) and overall survival (median, 28 v 77 months; P < .0001). In both subtypes, however, patients with less than two residual lymphoma manifestations in remission experienced a relatively good prognosis with an estimated 5-year survival of greater than 60% for MCL and greater than 75% for FCL.

CONCLUSION

MCL and FCL differ substantially in their features of presentation, response to chemotherapy, and long-term prognosis. The extent of residual disease after completion of chemotherapy discriminates patients with different prognosis and may be used for the stratification of postremission strategies.

Clinical outcome and economic impact of aminoglycoside peak concentrations in febrile immunocompromised patients with hematologic malignancies

The aim of this study was to investigate the clinical and economic significance of aminoglycoside peak concentrations in febrile neutropenic patients with hematologic malignancies. Sixty-one patients were treated according to protocol II of the Paul-Ehrlich-Gesellschaft: initial application of gentamicin or tobramycin in combination with a cephalosporin or ureidopenicillin and, after 3 days, a potential change of antibiosis to be decided in case of nonresponse. At the same time, samples were collected by an independent controller. We found a significant dependence of clinical outcome on aminoglycoside peak concentrations (P = 0.004). Twelve of 17 patients with peak concentrations > 4.8 mg/L, but only 13 of 44 patients with concentrations < or = 4.8 mg/L, responded to initial therapy. Average infection-related costs per patient with peak values > 4.8 mg/L were US$1429, $1790, and $1701 for nursing, diagnostics, and therapeutics, respectively (total $4920). Expenses for patients with peak concentrations < or = 4.8 mg/L were approximately 1.8-fold higher (average total $8718). If all 61 patients had achieved peaks > 4.8 mg/L, the potential savings would have totalled $167,112. We conclude that neutropenic patients form a target group for successful pharmacokinetic intervention and cost saving.

Oral idarubicin pharmacokinetics--correlation of trough level with idarubicin area under curve

Idarubicin is the first anthracycline that can be successfully administered via the oral route and thus may facilitate antineoplastic chemotherapy in an improved quality of life. These perspectives are somewhat hampered by the large variation in bioavailability between individual patients and the obvious requirement to monitor plasma concentration and area-under-the-curve values (AUC) for an appropriate adjustment of idarubicin dose. In this study we describe the pharmacokinetics of idarubicin and its main metabolite idarubicinol in 12 patients after oral application of 20 mg/m2 idarubicin on 3 consecutive days and demonstrate that the 24 h trough levels show a high correlation with AUC and may thus allow a rapid and easy determination of individual drug concentrations and an appropriate dose adjustment. The average terminal half-life was 30.5 h for idarubicin and 66.9 h for idarubicinol. The AUC for idarubicin and its main metabolite idarubicinol revealed a substantial interpatient variation with AUC values ranging from 25.7 to 114 ng x h/ml (average 58.1 ng x h/ml) for idarubicin and from 109.4-445.2 ng x h/ml (average 287.3 ng x h/ml) for idarubicinol. However, the ratio of idarubicin/idarubicinol differed only two folds from 1:3.7 to 1:7.7 with an average of 1:5.1. Both idarubicin and idarubicinol concentrations were highly reproducible, however, upon measurements after repeated applications within individual patients. Moreover, idarubicinol and idarubicin AUCs showed a good correlation with r = 0.78, indicating that the interindividual variation of idarubicin AUC reflects differences in absorption rather than in metabolism. In order to describe the interindividual bioavailability of idarubicin - represented by the respective AUC - measurement of a single data point with a high correlation with the AUC would be ideal. Our study demonstrates that the 24 h trough level shows such an excellent correlation (r = 0.96) with AUC, making it the perfect candidate for fast estimates of the individual bioavailability in a given patient. On this basis, the longitudinal measurement of the 24 h trough level may allow assessment of the impact of interindividual variations in AUC on clinical outcome and toxicity.

Treatment of follicular follicle centre lymphomas: current status and future perspectives

Follicle centre lymphomas (FCLs) comprise the predominant subtype of indolent nodal lymphomas. Therapy is based on the stage of the disease and consists of extended field or total nodal irradiation in stages I and II. Patients with advanced stages III and IV may initially remain untreated and be watched until the occurrence of disease-related symptoms such as B-symptoms, haematopoietic insufficiency, lymphoma progression or bulky disease. On the occurrence of these signs a cytoreductive chemotherapy of mild to moderate intensity such as cyclophosphamide, vincristine, prednisone (COP) or mitoxantrone, chlorambucil, prednisone (MCP) should be initiated. In responding cases maintenance with interferon-alpha (IFN alpha) leads to a significant prolongation of the progression-free interval. Modifications of this approach include the upfront combination of IFN alpha with anthracycline containing combinations such as cyclophosphamide, doxorubicin, teniposide, prednisone (CHVP). New perspectives arise from the introduction of myelo-ablative radio-chemotherapy with subsequent stem-cell transplantation and antibody-based immunobiological therapies.

Activity of thymidine kinase and of polymerase alpha as well as activity and gene expression of deoxycytidine deaminase in leukemic blasts are correlated with clinical response in the setting of granulocyte-macrophage colony-stimulating factor-based priming before and during TAD-9 induction therapy in acute myeloid leukemia

The present study was undertaken to assess the predictive value of pretherapeutic determinants of ara-C metabolism and proliferative activity of leukemic blasts for early response to antileukemic therapy in the setting of granulocyte-macrophage colony-stimulating factor (GM-CSF)-based priming before and during TAD-9 induction in 36 consecutive patients with de novo acute myeloid leukemia (AML). Ara-C metabolism was assessed by the activities of deoxycytidine kinase (DCK), deoxycytidine deaminase (DCD), DNA polymerase alpha (Poly alpha), and overall polymerase (overall Poly). The fraction of cells in S phase (%S phase) and thymidine kinase (TK) activity were determined as a measure of proliferative activity. Early response to therapy was defined by the percentage of leukemic blasts in the bone marrow 5 to 7 days after completion of TAD-9 with less than 5% signaling an adequate response and greater than 5% indicating an inadequate early reduction, respectively. While neither %S phase, DCK, nor overall Poly activity were predictive for early response, TK and Poly alpha activities were significantly higher for cases with adequate blast cell clearance. The respective median values were for TK 3.8 versus 1.85 pmol/min/mg protein (P = .012), and for Poly alpha 1.9 versus 0.69 pmol/min/mg protein (P = .014). An inverse relation was detected for DCD activity which was significantly lower in responding patients with a median of 0.33 nmol/min/mg protein (range, 0.0 to 29.5) as compared to a median of 5.1 nmol/min/mg protein (range, 0.11 to 8.45) in early nonresponders, (P = .009). Taking the respective median values as arbitrary cut-points for high or low enzyme activities, responders and nonresponders could be discriminated prospectively. Hence, 14 of 16 cases (88%) with DCD activities below the median of 1.56 nmol/min/mg protein responded as compared to only 3 of 14 (22%) patients with higher DCD activities (P = .0004). From the 15 patients with TK activity above the overall median of 3.2 pmol/min/mg protein, 11 cases (73%) achieved an adequate blast cell clearance while only 6 of 17 cases (35%) with lower values responded (P = .035). Similarly, 12 of 15 patients (80%) with high Poly alpha levels (>1.22 pmol/min/mg protein) responded to induction therapy as compared to only 5 of 14 patients (36%) with lower enzyme activities (P = .02). By logistic regression analysis of enzyme activities, DCD activity was found to be the most sensitive parameter to predict an adequate blast cell clearance (P = .032). Activities of DCD and TK were not only associated with initial response but were also found predictive for remission duration. Hence, from 11 patients with low TK levels 8 (73%) relapsed within 1 year, whereas only 2 of 11 (18%) patients with high TK activity experienced a recurrence of their disease (P = .015). Six of 9 (66%) patients with higher than median DCD levels relapsed within 1 year, whereas 10 of 14 patients (71%) with lower DCD levels had a longer remission duration (P = .085). Analysis of DCD gene expression at the mRNA level by a semi-quantitative reverse transcriptase-polymerase chain reaction method showed that a high transcription rate of the DCD gene was associated with high enzyme activities and vice versa. Hence, the observed intraindividual differences in DCD activity are a reflection of differences in gene activity and transcription rate rather than of variants in translation. Although further analyses are needed to elucidate the molecular mechanisms that determine the variation of enzyme activities in individual patients, the present study strongly suggests that pretherapeutic determination of TK and Poly alpha as well as of DCD allows to predict response to TAD-9 + GM-CSF induction therapy and may provide the means for the development of a risk adapted treatment strategy.

High antileukemic activity of sequential high dose cytosine arabinoside and mitoxantrone in patients with refractory acute leukemias. Results of a clinical phase II study

BACKGROUND

The current study was initiated to assess the efficacy and side effects of a timed sequential application of high dose cytosine arabinoside (AraC) in combination with mitoxantrone (S-HAM) in patients with refractory acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL).

METHODS

Patients with refractory AML or ALL were eligible for S-HAM salvage therapy, which was comprised of AraC, 1 g/m2 or 3 g/m2 every 12 hours, on Days 1, 2, 8, and 9 and mitoxantrone, 10 mg/m2/day, given on Days 3, 4, 10, and 11.

RESULTS

Of 22 fully evaluable patients, 14 patients (64%) achieved a complete remission whereas 5 patients (23%) succumbed to early death and 3 patients (14%) did not respond. Blood counts recovered at a median of 33.5 days after the start of treatment and complete remission was achieved after a median of 38 days. The median duration of complete remission was 4 months (range, 1-14 months) whereas overall survival time lasted for a median of 4.5 months (range, 1-30+ months). Treatment-associated toxicity was comprised predominantly of infection and diarrhea that reached World Health Organization Grades 3 and 4 in 64% and 32% of patients, respectively. Complementary pharmacokinetic evaluations of plasma AraC and AraU levels revealed no impact of initial AraC administration on the pharmacokinetics of subsequent AraC administrations and failed to demonstrate any evidence of self-potentiation.

CONCLUSIONS

The clinical data show the S-HAM regimen to be a promising approach for the treatment of patients with advanced acute leukemias. However, further evaluation at earlier stages of treatment is needed.

Response to cytarabine ocfosfate (YNK01) in a patient with chronic lymphocytic leukemia refractory to treatment with chlorambucil/prednisone, fludarabine, and prednimustine/mitoxantrone

Cytarabine ocfosfate (YNK01) is a novel orally applicable prodrug of cytosine arabinoside. Recent pharmacokinetic studies have revealed a prolonged release of the cytotoxic agent cytosine arabinoside (araC) from hepatocytes into the systemic circulation, resulting in a half-life of approximately 24 h for araC. The specific pharmacokinetic characteristics of cytarabine ocfosfate lead to a prolonged exposure of leukemic cells to this antineoplasstic agent during the 14-day cycle. the oral applicability during outpatient treatment and the sustained antineoplastic activity of araC against slowly proliferating leukemic B-cells suggest that cytarabine ocfosfate might be a useful drug in the treatment of chronic lymphocytic leukemia. Four years after diagnosis of B-CLL, a 50-year-old patient was started on cytarabine ocfosfate. Sequentially, the patient's disease had proved refractory to treatment with chlorambucil/prednisone (31 months), fludarabine (5 months), and prednimustine/mitoxantrone (3 months). These established regimens were discontinued because of increasing lymphocytosis, significant thrombocytopenia, and progressive B-symptoms. Following three cycles of cytarabine ocfosfate B-symptoms resolved, lymphadenopathy disappeared, and thrombocytopenia was significantly reduced. The patient has been free of these symptoms on a dosage of 1500 mg cytarabine ocfosfate/day (cycle of 14 days with intervals of 14-21 days) for 24 months and remains in an ongoing partial remission.

Optimizing therapy for acute myeloid leukemia based on differences in intracellular metabolism of cytosine arabinoside between leukemic blasts and normal mononuclear blood cells

The increasing insights into the pharmacokinetics and the metabolism of arabinoside C (AraC) have improved the rationale for its application in leukemia therapy and have led to a pharmacologically directed design of antileukemic treatment. The current study aims at adding to this approach by detecting differences in the intracellular metabolism of AraC 5'-triphosphate (AraCTP) between leukemic and normal mononuclear blood cells. Measurements of intracellular AraCTP levels were complemented by determinations of plasma AraC and arabinoside uridine (AraU) concentrations and were performed in 26 patients with acute myeloid leukemia (AML) who were undergoing combination therapy, including high-dose (1.0 or 3.0 g/m2 x 2/day) AraC. Plasma AraC concentrations showed a linear relationship to the applied AraC dose but did not correlate with intracellular AraCTP levels. Substantial differences in AraCTP retention times were revealed, during 3-h infusions of either 1.0 or 3.0 g/m2 AraC in leukemic blasts from 10 patients with t1/2 values of 1.60-7.63 h (median, 2.42 h). In addition, AraCTP levels declined in only one patient by > 10% within the first hour after the end of therapy and remained constant or even increased up to 1.5-fold during a posttreatment period of 1-2.5 h in the other nine cases. In contrast, AraCTP retention times were relatively uniform in normal mononuclear blood cells from 11 patients, with t1/2 values of 3.34-5.29 h (median, 3.85 h). More importantly, AraCTP levels dropped by > 10% within the first hour after the end of the high-dose AraC infusion in eight of 11 cases. A posttherapeutic increase of > 10% was not observed in any patient. These differences in AraCTP pharmacokinetics between leukemic and normal blood cells provided the basis for a modified timing of AraC administration with the aim of selectively maintaining cytotoxic AraCTP levels in leukemic blasts while allowing an intermittent drop of AraCTP levels in normal cells. This modification may result in higher antileukemic activity without increasing the damaging effect on normal cells and may, thus, improve the therapeutic index for AraC.

De novo AML with dysplastic hematopoiesis: cytogenetic and prognostic significance

Dysplastic hematopoiesis is the morphological hallmark of myelodysplastic syndromes. Dysplastic features in one or more lineages are also found frequently in bone marrow aspirates from patients with de novo AML and have been associated with an unfavorable prognosis. We asked whether dyshematopoiesis is an independent prognostic factor or an indicator of unrecognized secondary leukemia, identified by characteristic chromosomal abnormalities. Bone marrow aspirates from 102 patients with newly diagnosed AML were analyzed. Morphological analysis was obtained in all patients, flow cytometric analysis in 96 and successful cytogenetic analysis in 65 bone marrow aspirates. Dysgranulopoiesis (DysG) was found in 55, dysmegakaryopoiesis (DysM) in 32 and dyserythropoiesis (DysE) in 23 patients. Decreased side scatter signals of neutrophils in the flow cytometric analysis (DysS) were detected in 32 patients. DysG and DysS showed a highly significant correlation (P = 0.0005). DysG was an adverse negative prognostic factor for remission rate and event-free survival (P = 0.04, P = 0.02). An unfavorable karyotype was associated with a significantly lower chance for event-free survival (P = 0.002). The incidence of an unfavorable karyotype was significantly higher in patients with DysG (P = 0.01), DysM (P = 0.02) and DysS (P = 0.01). In patients with an unfavorable karyotype, dysplasia had no additional prognostic influence, however, in patients with a normal, favorable or prognostically uncertain karyotype DysG remained a predictor of lower remission rate (P = 0.03). We conclude that dysgranulopoiesis, dysmegakaryopoiesis and decreased side scatter signals of neutrophils are indicators of secondary leukemias in bone marrow aspirates from patients with de novo AML.

Prednimustine, mitoxantrone (PmM) vs cyclophosphamide, vincristine, prednisone (COP) for the treatment of advanced low-grade non-Hodgkin's lymphoma. German Low-Grade Lymphoma Study Group

The current study was initiated to compare the anti-lymphoma activity and side-effects of prednimustine/mitoxantrone (PmM) vs cyclophosphamide, vincristine, prednisone (COP) in patients with advanced low-grade non-Hodgkin's lymphomas in way of a prospective randomized multicenter trial. Two hundred and forty-six patients with stage III or IV centroblastic-centrocytic (CB-CC (Kiel-classification)) or follicle center lymphoma (FCL (REAL classification)) and centrocytic (CC) or mantle-cell-lymphoma (MCL) were randomized for therapy with either PmM or COP and are fully evaluable for response and toxicity. PmM consisted of prednimustine 100 mg/m2/day on days 1-5 and mitoxantrone 8 mg/m2 /day days 1 and 2, while COP comprised cyclophosphamide 400 mg/m2/day on days 1-5, vincristine 1.4 mg/m2/day on day 1 and prednisone 100 mg/m2/day on days 1-5. Both regimens were repeated for a total of six cycles followed by an additional two courses for consolidation in responding cases and a subsequent second randomization for interferon alpha maintenance vs observation only. Overall response rates were comparable with 83% complete and partial remissions after COP and 84% remissions after PmM. PmM revealed a significantly higher rate of complete remissions (36 vs 18%, P < 0.006), the majority being achieved after four courses. The more rapid and possibly also more effective reduction of the lymphoma cell mass by PmM resulted in a tendency to a longer event-free interval for patients achieving remissions after PmM as compared to COP with estimated median event-free intervals of 31 vs 14 months, respectively (P=0.04). Separate analysis of lymphoma subtypes showed a tendency to a lower rate of complete remission in CC or MCL as compared to CB-CC or FCL (16 vs 30%, P=0.12, NS) while overall response rates were in a similar range (81 vs 85%). In both subtypes, PmM induced a higher rate of complete remission while overall response rates were comparable after PmM or COP. Treatment associated side-effects comprised predominantly myelosuppression and granulocytopenia in particular which was more frequently observed after PmM than COP (43 vs 31 %, P < 0.0001). This difference was clinically irrelevant, however, since serious infectious complications were encountered in less than 3% of cycles after both regimens. COP therapy was associated with a significantly higher incidence and degree of hair loss and complete alopecia (31 vs 2%) as well as of peripheral neurotoxicity (23 vs 2%). These data show that both PmM and COP reveal a high anti-lymphoma activity in patients with advanced stage non-Hodgkin's lymphoma. PmM appears advantageous with a higher rate of complete remissions and a better tolerability with regard to secondary side-effects. A longer follow-up is needed to assess the long-term effects of initial treatment on disease-free and overall survival and the impact on additional maintenance therapy with interferon alpha.

Oral idarubicin pharmacokinetics--correlation of trough level with idarubicin area under curve

Idarubicin is the first anthracycline that can be successfully administered via the oral route and thus may facilitate antineoplastic chemotherapy at an improved quality of life. These perspectives are somewhat hampered by the large variation in bioavailability between individual patients and the obvious requirement to monitor plasma concentration and area-under the curve values (AUC) for an appropriate adjustment of idarubicin dose. In this study we describe the pharmacokinetics of idarubicin and its main metabolite idarubicin in 12 patients after oral application of 20 mg/m2 idarubicin on 3 consecutive days and demonstrate that the 24-h trough levels shows high correlation with AUC and may thus allow a rapid and easy determination of individual drug concentrations and an appropriate dose adjustment. The average terminal half-life was 30.5h for idarubicin and 66.9 h for idarubicinol. The AUC for idarubicin and its main metabolite idarubicinol revealed a substantial interpatient variation with AUC values ranging from 25.7 to 114 ng x h/ml (average 58.1 ng x h/ml) for idarubicin and from 109.4 - 445.2 ng x h/ml (average 287.3 ng x h/ml) for idarubicinol. However, the ratio of idarubicin/idarubicinol differed only two-fold from 1:3.7 to 1:7.7 with an average of 1:5.1. Both idarubicin and idarubicinol concentrations were highly reproducible, however, upon measurements after repeated applications within individual patients. Moreover, idarubicinol and idarubicin AUCs showed a good correlation with r=0.78, indicating that the interindividual variations of idarubicin AUC reflects differences in absorptions rather than metabolism. In order to describe the interindividual bioavailability of idarubicin - represented by AUC - measurement of a single data point with a high correlation with the AUC would be ideal. Our study demonstrates that the 24-h trough level shows such an excellent correlation (r=0.96) with AUC, making it the perfect candidate for fast estimates of the individual bioavailability in a given patient. On this basis, the longitudinal measurement of the 24-h trough level may allow the assessment of the impact of interindividual variations in AUC of clinical outcome and toxicity.