Cellular pharmacodynamics and plasma pharmacokinetics of parenterally infused hydroxyurea during a phase I clinical trial in chronic myelogenous leukemia.

PURPOSE: To determine the maximum-tolerated dose (MTD), toxicities, and antileukemic activity of hydroxyurea (HU) administered intravenously to patients with advanced-phase chronic myelogenous leukemia (CML). Further objectives were to analyze pharmacodynamic effect on deoxynucleotides (dNTPs) and to seek relationships between the decrease in dNTP pools and inhibition of DNA synthesis in CML blasts. PATIENTS AND METHODS: HU (8, 12, 18, 27, and 40 g/m2) was administered intravenously by a 24-hour continuous infusion to 19 adults with CML in blastic or accelerated phase. Plasma levels of HU were analyzed in all patients. To determine the role of HU in inhibiting ribonucleotide reductase, dNTP pools in the leukemia cells were quantitated. Correlations were sought with these parameters and DNA synthesis inhibition measured ex vivo by [3H]thymidine incorporation. RESULTS: The MTD of HU given as a 24-hour infusion was 27 g/m2. The dose-limiting toxicity was mucositis. There was a significant but transient myelosuppression, with nadir counts generally seen 3 to 4 days after the dose. The steady-state concentration of HU in plasma was achieved by 6 hours, and was proportional to the dose. There was a median 57% decrease in the deoxyadenosine triphosphate (dATP) pool in circulating blasts. In contrast, deoxyguanosine triphosphate (dGTP) and pyrimidine dNTPs were not significantly affected. The extent of DNA synthesis inhibition was related to the residual concentrations of intracellular dATP. CONCLUSION: A 24-hour infusion of HU results in significant but transient myelosuppression in advanced-phase CML. The specific decrease of intracellular dATP correlated with the inhibition of DNA synthesis in CML blasts. This pharmacodynamic action of HU provides a rationale for combination with other chemotherapeutic agents, the effects of which could be augmented by the decline in dATP pools.

Richter's syndrome: a report on 39 patients.

PURPOSE: The incidence, clinical features, laboratory findings, and treatment results of 39 patients with Richter's syndrome (RS) are reported. PATIENTS AND METHODS: Thirty-nine of 1,374 patients with chronic lymphocytic leukemia (CLL) developed RS. RESULTS: Features associated with RS included systemic symptoms (59%), progressive lymphadenopathy (64%), extranodal involvement (41%), elevation of lactate dehydrogenase (LDH; 82%), and a monoclonal gammopathy (44%). Analysis of the CLL karyotype showed no specific chromosomal abnormality that conferred increased risk; however, multiple abnormalities were common. Patients at all Rai stages and in complete response (CR) were at risk, including three CR patients with no residual disease at the level of detection by dual-parameter flow cytometry or restriction analysis for immunoglobulin (Ig) gene rearrangements. The incidence was not higher in patients who had received prior fludarabine or chlorodeoxyadenosine. The median survival duration was only 5 months, despite multiagent therapy. Patients who responded had prolonged survival durations (P < .001). Three of eight patients who survived more than 1 year had a de novo presentation of both CLL and large-cell lymphoma (LCL). Comparison of surface light-chain analysis from both low- and high-grade components demonstrated isotypic light-chain expression in 12 of 15 patients. Ig heavy- and light-chain gene rearrangement analysis showed identical rearrangement patterns in five of five patients. CONCLUSION: The clinical, laboratory, and survival characteristics of our RS patients were similar to those reported in earlier studies. Ig gene rearrangement and light-chain isotype analysis support a common origin for CLL and LCL. Despite progress in the treatment of CLL, the development of LCL remains a serious complication and continued surveillance in all CLL patients is warranted.

Use of granulocyte colony-stimulating factor before, during, and after fludarabine plus cytarabine induction therapy of newly diagnosed acute myelogenous leukemia or myelodysplastic syndromes: comparison with fludarabine plus cytarabine without granulocyte colony-stimulating factor.

PURPOSE: To determine whether granulocyte colony-stimulating factor (G-CSF) administered before, during, and after fludarabine plus cytarabine (ara-C; FA) chemotherapy affected complete response (CR) rate, infection rate, blood count recovery, or survival in patients with newly diagnosed acute myelogenous leukemia (AML) or myelodysplastic syndromes (MDS). PATIENTS AND METHODS: A total of 112 patients with newly diagnosed AML (n = 69) or MDS (n = 43) received G-CSF 400 micrograms/m2/d 1 day before (presenting WBC count < 50,000/microL) and/or during (all patients) fludarabine 30 mg/m2/d and ara-C 2 g/m2/d for 5 days (FLAG). G-CSF continued until a CR was achieved. Results were compared with those in 85 newly diagnosed patients (54 AML, 31 MDS) previously treated with FA without G-CSF. RESULTS: Patients in both groups were relatively old (median age of all patients, 63 years), and were likely to have prognostically unfavorable cytogenetic abnormalities (36% had abnormalities of chromosomes 5 and 7 [-5/-7]). G-CSF accelerated recovery to > or = 1,000 neutrophils (P < .0001; median, 34 days for FA, 21 days for FLAG), but logistic regression provided no evidence that the CR rate was higher with FLAG than with FA (P = .50), with unadjusted CR rates of 63% and 53%, respectively. This may reflect relatively high rates of death before neutrophil recovery in both groups. Rates of infection were similar in both groups. The follow-up duration in remission is short, and much of these data remain censored. To date, survival is similar with FA and FLAG. CONCLUSION: On average, G-CSF before, during, and after FA had no effect on CR or infection rates in this population, in which elderly patients and poor prognostic factors were prevalent. The use of FA and laminar airflow rooms rather than more usual therapy needs to be considered when analyzing the results.

Discordant bone marrow involvement in diffuse large-cell lymphoma: a distinct clinical-pathologic entity associated with a continuous risk of relapse.

From 1975 to 1988, 50 patients with lymph node biopsy-documented diffuse large-cell lymphoma (DLCL) presented with bone marrow involvement. Twenty-four patients (48%) had large-cell lymphoma (LCL) in the bone marrow and were compared with 19 (38%) patients who had small cleaved-cell lymphoma (SCCL) in the marrow. Additionally, seven patients (14%) had mixed small- and large-cell lymphoma (ML) in the marrow. Patients who had LCL marrow involvement were younger (P less than .02) and more frequently had elevated lactic dehydrogenase (LDH) levels (P less than .001), high tumor burden (P less than .01), and more sites of extranodal disease (P less than .05) than those with SCCL in the marrow. The complete response (CR) rate to multiagent chemotherapy was 16.7% in the LCL group and 89.4% in the SCCL group (P less than .001). One third of the patients with LCL in the marrow developed CNS involvement, compared with only one patient in the SCCL group (P = .06). Overall 5-year survival was 79% in patients with SCCL marrow involvement, compared with only 12% in patients with LCL in the marrow (P = .002). Despite a high CR rate, patients with marrow involved by SCCL were at a high continuous risk of relapse with only a 30% failure-free survival at 5 years. We conclude that bone marrow involvement with LCL predicts for extremely poor prognosis with low response rate and short survival. Patients with SCCL in the bone marrow have a high rate of CR and a high rate of 5-year survival; however, there is a high risk of late relapse, and only 15% are in a continuous remission at 8 years.

2-Chlorodeoxyadenosine therapy for idiopathic hypereosinophilic syndrome.

Idiopathic hypereosinophilic syndrome (HES) is a rare disease with no established effective therapy. It has been reported that interleukin-5 (IL-5) produced by helper T cells plays a major role in the proliferation of eosinophils. The nucleotide analogue 2-chlorodeoxyadenosine (2-CdA), which induces excellent clinical responses in hairy cell leukemia, is known to suppress helper T cells; therefore, we used 2-CdA, alone or in combination with cytarabine, to treat patients with idiopathic HES. 2-CdA alone and combined with cytarabine resulted in a rapid and sustained decrease in circulating eosinophils in two patients with idiopathic HES that was refractory to steroids, hydroxyurea and cytarabine. The efficacy of 2-CdA alone and combined with cytarabine exceeded by far that of cytarabine alone. However, reverse transcription-polymerase chain reaction (RT-PCR) did not show production of IL-5 or granulocyte-macrophage colony-stimulating factor mRNA in T cells as previously reported, and multiple cytokine receptors were found on eosinophils in idiopathic HES, suggesting that IL-5 may not be the sole cytokine involved in the regulation of idiopathic HES. The clinical efficacy of 2-CdA in idiopathic HES needs to be established on a large group of patients.

Bcl-2 expression in chronic lymphocytic leukemia and its correlation with the induction of apoptosis and clinical outcome.

Transcriptional deregulation of the Bcl-2 gene has been demonstrated to extend cell viability via an inhibition of apoptotic cell death. Chronic lymphocytic leukemia (CLL) cells are inherently susceptible to apoptosis during short-term culture. Because increased expression of the Bcl-2 gene has been reported in CLL, we sought to correlate Bcl-2 protein expression with the in vitro propensity towards apoptosis and also clinical outcome. Immunoblot analysis of Bcl-2 protein revealed interpatient variability with nine of 42 (21%) cases demonstrating similar or greater expression than a t(14;18) containing lymphoma cell line and 18 of 42 (43%) cases demonstrating a level of expression similar to or less than that seen in normal peripheral blood lymphocytes. Bcl-2 expression did not correlate with clinical features, or with apoptosis, as measured by an in vitro DNA fragmentation assay. However, analysis of survival in the 33 untreated patients revealed significant differences based on the level of Bcl-2 expression, with higher expression being an adverse feature (P<0.02). This data suggests that Bcl-2 is important in the pathogenesis and progression of CLL and that quantitation of Bcl-2 protein may provide useful prognostic information.

Acute lymphoblastic leukemia following preleukemic syndromes in adults.

Preleukemic syndromes (PLS) evolve to acute myeloid leukemia (AML) in 15-50% of cases, but rarely transform to acute lymphoblastic leukemia (ALL). AML following preleukemic syndromes has a poor prognosis, but little is reported about the outcome of secondary ALL. From the adult leukemia database at MD Anderson Cancer Center, nine patients with ALL following myelodysplastic syndrome (MDS) (n=6), smoldering leukemia (n=1), or cytopenias with dysplastic features (n=2) were identified. Clinical and laboratory features were abstracted from the database, patient charts, review of the bone marrows and special laboratory studies. The median interval from diagnosis of PLS to ALL was 6 months. Blasts with lymphoid morphology and terminal deoxynucleotidyltransferase (TdT) and periodic acid Schiff (PAS) staining were present in eight of nine cases and four of six cases respectively. T cell and myeloid markers were expressed in the majority of cases, but T cell gene rearrangements were not detected. Only one patient had electron microscopic myeloperoxidase-positive staining. Two patients later transformed to AML. Patients were predominantly male (89%) with a median age of 69 years. The complete remission (CR) rate with ALL-directed chemotherapy (78%) was comparable to that of other adult ALL patients (74%) (n=327) without excess myelosuppression. Marrow dysplasia persisted in CR in three of seven cases. The median remission duration of 16 months (range 4.5 to 51+ months) and the median overall survival of 21 months (range 1 to 55+ months) were comparable to that of ALL patients overall. ALL following preleukemic syndromes is a distinct syndrome with T cell and myeloid markers and responds well to ALL-directed therapy. The presence of myeloid and lymphoid markers suggests the transformation of an early stem cell.

Therapy-related leukemia and myelodysplastic syndrome in chronic lymphocytic leukemia.

A retrospective analysis was performed to determine the incidence and clinical features of acute myelogenous leukemia/myelodysplastic syndrome (AML/MDS) developing in chronic lymphocytic leukemia (CLL) patients. AML/MDS occurred in 3/1374 CLL patients seen at a single institution between 1972 and 1992. The median follow-up exceeded 7 years and 72% of these patients had received prior alkylating agent therapy. The expected number of AML/MDS developing in a general population of the same size was 1.2 as calculated from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program data (observed-to-expected ratio = 2.49; 95% confidence interval = 0.9-7.3; p = 0.12). Although, not included in the incidence calculation, four patients with CLL were referred at the time of development of AML/MDS. CLL and AML/MDS were diagnosed concurrently in two patients. Three of the patients had received no prior alkylating agents. The median survival was 17 months in patients who had received no prior treatment, and 5 months in those who had received prior chemotherapy. Our results suggest that patients with CLL in whom AML/MDS develops have similar prognoses to other patients with AML/MDS. Furthermore, this analysis does not provide evidence for a heightened risk of AML/MDS in CLL patients, despite treatment with known leukemogenic agents.

Fludarabine plus doxorubicin in previously treated chronic lymphocytic leukemia.

Based on the activity of fludarabine and doxorubicin in chronic lymphocytic leukemia (CLL), 30 patients received this combination. The median age of these patients was 61 years; median Zubrod performance status was one; median number of prior therapies was three; and median time to treatment was 53 months. Rai stage was 0 for two patients, I/II for 19 patients, and III/IV for nine patients. Prior treatment included fludarabine in 25 patients. In this regimen, fludarabine was administered as 30 mg/m2/d IV x 3 to 10 patients, 25 mg/m2/d IV x 4 to three patients, and to 17 patients as 30 mg/m2/d IV x 4. A 50 mg/m2 IV dose of doxorubicin was given to all patients. The first 17 patients received prednisone 30 mg/m2 x 5 days; however, this was discontinued due to other data demonstrating no therapeutic advantage and increased opportunistic infections when corticosteroids were added to fludarabine. Toxicity consisted primarily of infectious episodes: pneumonia nine, bacteremia one, FUO seven, and minor infection five. Two deaths from pneumonia occurred. Standard guidelines for response were used with the addition of a nodular CR group. Despite prior treatment with fludarabine in the majority of patients, the response rate in the 29 evaluable patients was CR 3%, nodular CR 17%, PR 35%, fail 38% and early death 7%. This combination of fludarabine and doxorubicin is active against CLL and warrants further study.

A 3-day schedule of fludarabine in previously treated chronic lymphocytic leukemia.

This study was undertaken to determine the efficacy and toxicity of a shorter schedule of fludarabine administration (30 mg/m2 i.v. daily for 3 days every 4 weeks) in patients with previously treated chronic lymphocytic leukemia (CLL). Eighty patients with previously treated advanced (Rai III-IV) (54%) or progressive Rai stage 0-II (46%) were treated. The results of this trial were retrospectively compared with those of previous fludarabine trials using different schedules of administration. The complete response (CR), nodular CR and partial response rates were 10, 15 and 21%. The overall response rate (46%) was slightly lower than prior regimens using a 5-day schedule of fludarabine; however, this difference was not significant. Further evaluation by dual-parameter flow cytometry and immunoglobulin gene rearrangement analysis revealed that minimal residual disease was more common in a 3-day schedule. The overall incidence of infections per treatment course (14%) was significantly lower than that observed on the 5-day or weekly regimens (P < 0.001). The incidence of minor, atypical and viral infections were similar. There was no difference in survival in the various trials. In conclusion, a 3-day schedule of fludarabine in previously treated CLL patients was associated with a lower infection rate and similar survival to a 5-day schedule. These data support the use of a 3-day schedule of fludarabine as a single agent and in combination with other active agents.

High molecular weight DNA fragmentation: a critical event in nucleoside analogue-induced apoptosis in leukemia cells.

Cleavage of DNA into internucleosomal fragments is one of the characteristics of apoptosis. However, searches for in vivo evidence of nucleosomal DNA fragmentation in leukemia cells freshly obtained from patients during chemotherapy frequently failed to reveal nucleosomal multimers (DNA ladders). It is not clear whether this type of DNA cleavage is an essential event in drug-induced apoptosis and thus a denominator of cell killing, or whether the internucleosomal DNA fragments are merely the by-products of the apoptotic process. Here, we report our investigation into the role of DNA fragmentation in apoptotic cell death induced by anticancer nucleoside analogues, both in cell culture and in leukemia patients undergoing chemotherapy. Using a 5'-end DNA-labeling technique and pulsed field gel electrophoresis, we detected fragmentation of DNA in two distinct size classes, internucleosomal and high molecular weight (predominantly 50 kb) DNA fragments, in a human leukemia cell line exposed to the nucleoside analogues fludarabine and gemcitabine. We further demonstrated that the two types of DNA fragmentation were separate events, distinguishable by their requirements for Ca2+ and responses to phorbol ester treatment. The drug-treated cells underwent morphological changes of apoptosis even after internucleosomal DNA fragmentation was selectively inhibited by intracellular Ca2+ chelation, or by treatment with phorbol ester. In contrast, neither apoptotic morphology nor internucleosomal DNA fragmentation was observed when the high molecular weight DNA fragmentation was blocked by inhibition of nucleoside analogue incorporation into DNA. These results suggest that cleavage of DNA into large fragments may be an initial event that is critical for drug-induced apoptosis, whereas activation of a Ca2+-dependent endonuclease to cleave DNA at internucleosomal sites is not an absolute requirement for the execution of the apoptotic cell death program. Further studies of leukemic lymphocytes obtained from 9 patients with chronic lymphocytic leukemia during therapy with fludarabine revealed high molecular weight DNA fragmentation, which was correlated with a decrease of peripheral lymphocytes in 6 patients, whereas only 1 of the 15 patients evaluated for nucleosomal DNA fragments showed the DNA ladders. These results indicate that high molecular weight DNA fragmentation occurs in vivo, and may be correlated with the cytotoxic action of the anticancer drugs. Further study of the association of high molecular weight DNA fragmentation with clinical response to chemotherapy is warranted.

The role of fludarabine in hematological malignancies.

Fludarabine monophosphate, a synthetic nucleoside analog, has been shown to have considerable activity in a number of lymphoid malignancies. In chronic lymphocytic leukemia the response rates can exceed 70% with a considerable proportion of complete remissions being attained. These rates are markedly superior to earlier therapies with which complete remission was uncommon. It also has significant activity in previously treated patients for whom effective salvage regimens were unsatisfactory. In addition, fludarabine shows substantial activity in low grade non-Hodgkin's lymphoma, both as initial treatment and as salvage therapy. Fludarabine is effective in Waldenstrom's macroglobulinemia and is active in other low grade lymphoid malignancies. Major toxicities are reversible myelosuppression and depletion of T lymphocytes. The use of fludarabine in hematological malignancies will be reviewed, with reference to its mode of action and future use in combination therapies.

Fludarabine: pharmacokinetics, mechanisms of action, and rationales for combination therapies.

Knowledge of the pharmacokinetics of a drug is essential to the optimal design of the dose and schedule of chemotherapy protocols. As an extension, an understanding of the mechanism of drug action is necessary to construct the optimal strategy for combination chemotherapy. Nucleoside antimetabolites such as fludarabine are pro-drugs that must enter cells and be phosphorylated to the nucleoside triphosphate before they can elicit biologic activity. Thus, knowledge of the pharmacokinetics of the triphosphate in target cells and an understanding of the mechanisms by which this active form of the drug act are indispensable to the rational design of treatment protocols. This article reviews the essential elements of the pharmacokinetics and mechanisms of action of fludarabine to provide a rationale for combinations of fludarabine with other chemotherapeutic agents and anti-cancer modalities.

New initiatives with fludarabine monophosphate in hematologic malignancies.

Fludarabine monophosphate (fludarabine) was initially discovered to have significant activity in indolent lymphoma and chronic lymphocytic leukemia (CLL). The major clinical experience with fludarabine is in previously treated patients with CLL. In such patients the complete and partial response rate (CR + PR) is over 50%. These results were obtained with 5-day schedules of fludarabine 25 to 30 mg/m2/d. Subsequent schedules have explored once-a-week fludarabine and a 3-day schedule every 4 weeks. These strategies, in particular the once-a-week schedule, have obtained inferior results. The addition of prednisone has not been associated with an improvement in response rate or survival. The application of fludarabine to previously untreated patients demonstrated a CR + PR rate of 75% to 80%. The addition of prednisone did not improve the response rate or survival in this group of patients. A significant concern in patients with CLL treated with fludarabine is a decrease in the CD4 and CD8 counts. Despite median posttreatment counts of approximately 200 CD4 lymphocytes/microL, the incidence of infections in patients in remission off therapy is low. Major clinical activity has been demonstrated with fludarabine in Waldenstrom's macroglobulinemia, in which more than one third of refractory patients achieve a CR or PR. Responding patients with anemia or thrombocytopenia have a marked improvement in blood counts. The duration of response has been long (> 30 months) in most responders. The early activity of fludarabine as a single agent in phase I/II studies in indolent lymphoma subsequently has been confirmed by a number of investigators. Fifty percent to 60% of patients with follicular lymphomas respond to fludarabine as a single agent. A number of these responses are complete despite the patients having received extensive prior treatment. A number of combination programs are being developed in CLL and indolent lymphoma. The combination of fludarabine with doxorubicin and prednisone has been developed and is being studied in phase I/II clinical trials. In addition, combinations of fludarabine and cytarabine with or without cisplatin based on elegant preclinical pharmacokinetic rationales have been applied to CLL with impressive cytoreductive activity but significant myelosuppression. A new combination of fludarabine, mitoxantrone, and dexamethasone has been developed for use in lymphoma. Phase I studies demonstrated a high response rate, especially in follicular lymphomas, with a number of patients achieving complete remission. Subsequent phase II studies demonstrate a response rate of 89% in patients with indolent lymphoma.(ABSTRACT TRUNCATED AT 400 WORDS)

Result of interferon-alpha therapy in patients with chronic myelogenous leukemia 60 years of age and older.

PURPOSE: To determine the response rate to interferon-alpha (IFN-alpha) in patients with chronic myelogenous leukemia (CML) aged 60 years and older. PATIENTS AND METHODS: Patients with CML aged 60 years and older included in all protocols with INF-alpha therapy for chronic phase CML at the M.D. Anderson Cancer Center were analyzed. They were treated with human leukocyte or recombinant human IFN-alpha 5x10(6) U/m2 daily alone or in combination with hydroxyurea or IFN gamma. The clinical characteristics of the patients were analyzed and their hematologic and cytogenetic responses to IFN-alpha and survival from the initiation of therapy were determined. Results were compared with those of younger patients treated in the same protocols. Treatment-related toxicity was also analyzed. RESULTS: Thirty-five of 274 (13%) patients included in trials of IFN-alpha-based regimens for CML were 60 years and older. Older patients had a higher percentage of bone marrow blasts (P = 0.04) and basophils (P = 0.09) than younger patients. Sixty-nine percent achieved a complete hematologic remission with IFN-alpha therapy, and 51% had a cytogenetic response, which was major in 26% and complete (Philadelphia chromosome-positive cells = 0%) in 20%, Their median survival was 64 months, and the estimated 5-year survival rate was 62%. These results were not different from those in younger patients. Twenty-two patients (63%) had at least grade 2 toxicity requiring dose adjustment. The most frequent side effects were neurotoxicity in 31% and chronic fatigue in 29%. CONCLUSIONS: Patients with CML 60 years of age and older respond well to IFN-alpha therapy, but experience more toxicity. This therapy should be considered for these patients if they are otherwise in good condition, with careful attention to IFN-alpha toxicity and its management.

Clinical experience with fludarabine in leukaemia.

Fludarabine (Fludara) is a new purine analogue that was first entered into clinical trials in 1982. Results of initial studies with high dosages (> 96 mg/m2/day for 5 to 7 days) of fludarabine in acute leukaemia showed significant cytoreductive activity but a high incidence of severe irreversible neurotoxicity. The results of subsequent studies with lower dosages of 25 to 30 mg/m2/day for 5 days in chronic lymphocytic leukaemia (CLL) and low grade lymphomas have shown this regimen to be effective and safe, with almost no significant neurotoxicity. At present, the major role of fludarabine in leukaemia is in the management of CLL. In previously treated patients with CLL, responses are obtained in more than 50% of patients, with two-thirds of those responses being complete remissions according to the National Cancer Institute Working Group (NCIWG) criteria for complete response and partial response. The major causes of morbidity associated with fludarabine in CLL are infections and febrile episodes. These occur more frequently in previously treated patients and those with advanced stage of disease. Myelosuppression is dose limiting and a small proportion of patients with CLL develop moderate to severe and sometimes protracted myelosuppression. Administration of combined fludarabine and cytarabine (cytosine arabinoside; ara-C) alone (FA regimen) or together with granulocyte colony-stimulating factor (FLAG regimen) produced high response rates in previously treated refractory patients with acute leukaemia and previously untreated patients with acute myelogenous leukaemia or myelodysplastic syndrome. The wide range of biochemical and biological activities of fludarabine suggests that it will have an expanding role in future combinations in the treatment of both acute and chronic leukaemias.

Fluorescence in situ hybridization identifies inversion 16 masked by t(10;16)(q24;q22), t(7;16)(q21;q22), and t(2;16)(q37;q22) in three cases of AML-M4Eo.

Bone marrow or peripheral blood from three patients had a t(10;16)(q24;q22), t(7;16) (q21;p13.1), and t(2;16)q37;q22), respectively. In all cases, fluorescence in situ hybridization confirmed an inv(16) masked by the translocation. The three patients were diagnosed with acute myelomonocytic leukemia and increased eosinophils. Because inv(16) has a favorable prognosis, identification of masked inv(16) will promote improved management of these cases. Therefore, all cases that have atypical rearrangement of chromosome 16 should be investigated for a possible inversion.

Combination of fludarabine and arabinosylcytosine for treatment of chronic lymphocytic leukemia: clinical efficacy and modulation of arabinosylcytosine pharmacology.

Previous studies have demonstrated that treatment with fludarabine 4 h prior to arabinosylcytosine (ara-C) potentiates the accumulation of the active triphosphate of ara-C (ara-CTP) in leukemic lymphocytes. The clinical efficacy of this combination was evaluated in 15 patients with chronic lymphocytic leukemia (CLL) that was advanced in their disease (median Rai stage, IV) and refractory to treatment with fludarabine. Patients received 0.5 g/m2 ara-C infused i.v. over 2 h followed at 20 h by a 30-min infusion of 30 mg/m2 fludarabine. At 24 h, an identical dose of ara-C was infused. To intensity the therapy and to determine the duration of fludarabine potentiation of ara-CTP accumulation, six additional patients with Rai stage III or IV CLL were treated with an amended 2-week protocol. On week 1, 30 mg/m2 fludarabine was infused over 30 min, followed 4 h later by a 2-h infusion of 0.5 g/m2 ara-C; on week 2, the fludarabine dose was followed 4 h later by a 4-h infusion of ara-C (1.0 g/m2). In all, 1 partial remission and 7 minor responses in 1 or more disease sites were observed in the 21 patients. The major treatment-related toxic effects were myelosuppression and infection. Comparison of the ara-CTP accumulation area under the concentration-time curve (AUC) in circulating CLL cells of patients on the amended protocol demonstrated a significant (P = 0.001) 1.6-fold (range, 1.4- to 2.0-fold) increase after fludarabine administration. Although the initial rates of ara-CTP accumulation were similar for the 2-h and 4-h infusions, ara-CTP accumulation continued for up to 4 h in four of five patients who received the longer infusion. The activity of the fludarabine and ara-C combination is being evaluated in in vitro model systems and in phase II clinical trials in combination with other drugs.

Natural killer cell activity in chronic lymphocytic leukemia patients treated with fludarabine.

Fludarabine, the 5'-monophosphate of 9-beta-D-arabinofuranosyl-2- fluoroadenine (FaraAMP), is effective in the treatment of chronic lymphocytic leukemia (CLL) and has been demonstrated to increase natural killer (NK) cell lytic activity (NKa) in humans and mice. To determine the effect of FaraAMP on NK cells in CLL, we analyzed NKa toward K562 targets after in vitro incubation with FaraAMP and after in vivo exposure to fludarabine. Pretreatment analysis of peripheral blood from 12 CLL patients (9 untreated) revealed: median number of NK cells 500/microliter (range 290-1160); median NKa lytic unit30/10(6) cells (range 5-80). These results were similar to those from healthy adult donors. After exposure to 3, 30 or 300 microM FaraAMP, the median maximum stimulation index (NKa FaraAMP/NKa) was 1.2 (range 0.9-1.5), within the range observed in normal adults. FaraA also stimulated NKa in vitro toward autologous CLL cells in two of five patients as measured by a dye-exclusion assay. In three patients following three or more treatment courses of fludarabine (30 mg/m2 per day for 5 days) the NK cell number and NKa were maintained near pretreatment values. Phenotypic analysis of the peripheral mononuclear cells in 34 consecutive CLL patients revealed a marked reduction in CD5/CD20 and CD4 cell numbers after three courses of fludarabine with less effect on CD8 and CD56 cells. These results indicate that fludarabine spares NK cells and may stimulate NKa in some CLL patients.

Survival of young patients with chronic lymphocytic leukemia failing fludarabine therapy: a basis for the use of myeloablative therapies.

We examined the survival of 91 young patients (< or = 55 years) with chronic lymphocytic leukemia from the time of failure of fludarabine therapy, in an attempt to identify those with a poor outcome who may benefit from investigative dose-intensive therapies. The median survival of patients unresponsive to fludarabine (n = 42) was 48 weeks, and only 11% responded to subsequent therapies. The median survival of patients relapsing following a fludarabine-induced remission (n = 49) was 87 weeks, and 83% of those who had received fludarabine as their first therapy (n = 14) responded to further fludarabine-containing therapies, with 60% alive at four years. Only 7% of those relapsing patients who had received fludarabine as salvage therapy (n = 35) responded to subsequent therapies (median survival 72 weeks). The poor outlook for these patients justifies the consideration of innovative dose-intensive therapies, such as bone marrow transplantation, with their attendant risk of toxicity.