Biomedical subjects
Publications and source records attributed to M J Keating.
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Bcl-2 expression is associated with the progression of prostate cancer from androgen-dependence to androgen-independence. Bcl-2 is an integral membrane protein which localizes to mitochondria, endoplasmic reticulum, and the nuclear envelope. Using spectrofluorometry and laser confocal microscopy, the ability of bcl-2 to modulate intracellular Ca2+ was examined in the Dunning G prostate carcinoma cell line following apoptosis induction by adriamycin. Adriamycin and thapsigargin, an endoplasmic reticulum Ca2+-pump inhibitor, were effective inducers of apoptosis in control, but not bcl-2 transfected, cells. Treatment with adriamycin was accompanied by a sustained rise in cytoplasmic Ca2+ in control and bcl-2 transfected cells. An increase in intranuclear Ca2+ was observed in control cells only. Apoptosis induction by thapsigargin was associated with an increase in cytoplasmic Ca2+ in control cells that was not detected in the resistant bcl-2 transfectants. Ca2+ was excluded from nuclei isolated from bcl-2 expressing cells, but was sequestered in control nuclei, following the addition of ATP. These findings suggest that bcl-2 may regulate levels of intranuclear Ca2+ independently of cytosolic Ca2+ levels. The ability of bcl-2 to modulate, directly or indirectly, sustained increases in both cytosolic and intranuclear Ca2+ may provide a common basis for bcl-2 function in different subcellular compartments.
The effectiveness of arabinosylcytosine (ara-C) for the treatment of acute myelogenous leukemia (AML) depends on the formation of its active metabolite, the triphosphate of ara-C (ara-CTP). Using biochemical modulation strategies to increase the accumulation of ara-CTP in leukemia blasts, a clinical protocol was designed combining 2-chlorodeoxyadenosine (CdA), an inhibitor of ribonucleotide reductase, and ara-C for adults with AML. The protocol stipulated an infusion of 1 g/m2 of ara-C over 2 hours on day 1. A continuous infusion of CdA (12 mg/m2/d) begun 24 hours later and continued for 5 days. Identical doses of ara-C were administered on days 3, 4, 5, and 6. Pharmacokinetic and pharmacodynamic interactions between CdA and ara-C during therapy were investigated. To complement these studies, molecular actions of the triphosphate of ara-C and CdA on DNA extension by human DNA polymerase alpha in an in vitro model system was conducted. In the circulating leukemia blasts of 7 of the 9 patients studied, ara-CTP pharmacokinetics showed a median 40% increase in the rate of ara-CTP accumulation after 24 hours of CdA infusion. The ex vivo effect of CdA on accumulation of ara-CTP in AML blasts was similar to that during therapy except that the enhancement was less. The DNA synthetic capacity of the circulating blasts was inhibited to a greater extent by administration of CdA and ara-C in combination than by either one alone. Additionally the lowered level of DNA synthesis was maintained until the next infusion of ara-C. Endogenous levels of deoxynucleotides increased 24 hours after ara-C infusion. Administration of CdA in general lowered the concentrations of all dNTPs. DNA pol alpha incorporated CdATP and ara-CTP with high affinity in a DNA primer extending over an oligonucleotide template of defined sequence. Human DNA polymerase alpha extended DNA primers terminated by CdA monophosphate (CdAMP) at its 3'-end by incorporating ara-C monophosphate (ara-CMP). The tandem incorporation of CdAMP and ara-CMP resulted in nearly complete inhibition of DNA primer extension. The insertion of two analogs in sequence, inhibition of ribonucleotide reductase, and the metabolic potentiation of ara-CTP by CdA infusion may be responsible for sustained inhibition of DNA synthesis in the circulating leukemia blasts during therapy with this combination regimen.
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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.
The observation of lymphopenia in children deficient in adenosine deaminase (ADA) led to exploration of an inhibitor of the enzyme in lymphoid malignancies; thus deoxycoformycin was the first purine nucleotide used in human trials. Fludarabine and 2-chlorodeoxyadenosine (2-CdA), agents resistant to deamination by ADA, have been utilized in the past decade. All of these drugs act as competitors for deoxyadenosine triphosphate at the A sites of the elongating DNA strand, terminating DNA synthesis. However, their remarkable efficacy in indolent lymphoid malignancies is not well explained by this mechanism of action. The induction of apoptosis and resultant cytotoxicity may be important in their activity. As a single agent, fludarabine has been associated with overall remission rates as high as 55% in previously treated patients and 79% in previously untreated patients. With this agent, a dosage regimen of 25-30 mg/m2 daily over 5 days seems to be the most effective to date. Fludarabine has shown more favorable remission rates than the traditional salvage regimens incorporating anthracyclines and alkylating agents. Regimens combining fludarabine with mitoxantrone and with doxorubicin have shown minimal therapeutic advantage in CLL, while combination with cyclophosphamide appears promising. Remission rates with deoxycoformycin have been lower than with fludarabine, but studies have been small in patient numbers. The agent 2-CdA, first successful in hairy-cell leukemia, has shown overall response rates in chronic lymphocytic leukemia similar to those seen with fludarabine. Whether or not cross-resistance occurs among the purine analogs has not been fully determined, but occasional patients with disease refractory to fludarabine have responded to 2-CdA. Cumulative myelosuppression and immunosuppression may be experienced however. In the B-cell neoplastic entity, Waldenström's macroglobulinemia, fludarabine therapy in patients previously treated with alkylating agents and/or steroids produced a 36% response rate. Only two previously untreated patients received fludarabine, and both responded. A similar response rate of 40% was seen when 2-CdA was administered to previously treated patients. This response rate increased to 85% in a study of 26 previously untreated patients, making this one of the most effective drugs yet investigated in this condition.
The overall cure rate of adults with newly-diagnosed acute myelogenous leukemia (AML) treated with continuous infusion high-dose cytarabine (CIHDAC) is comparable to that with standard-dose ara-C plus anthracycline or amsacrine (AMSA). We tested whether the addition of AMSA to CIH-DAC improves the outcome of adults with untreated AML. 75 patients with untreated AML were treated with AMSA (75 mg/m2/day x 4) plus CIHDAC (1.5 g/m2/day x 4) for induction and, if in complete remission (CR), early and late intensification. Results were compared to those in 129 patients treated on a previous study with CIHDAC alone. The principal comparison in both groups was between those 117 patients (AMSA/CIHDAC n = 52, CIHDAC n = 65) who met the initial eligibility criteria for the AMSA/CIHDAC study (risk of early mortality < or = 1) and who were treated at a time when relatively few eligible patients were excluded (19% in the AMSA/CIHDAC group, 34% in the CIHDAC group). There was no difference between regimens in CR rate, remission duration, or survival in this cohort. When attention was turned to all 204 patients, outcome was superior with AMSA/CIHDAC very largely as a result of outcome in patients with APL. Aside from these patients, addition of amsacrine to CIHDAC did not appear to be productive.
Patients developing Hodgkin's disease (HD) after a diagnosis of chronic lymphocytic leukemia (CLL), are frequently included in a series of patients with Richter's syndrome (RS). We sought to determine the natural history of the association of CLL and HD. Over a 21 year period, 1374 patients with CLL have been registered in our computer data base. Seven cases of CLL and HD have been documented and confirmed. The median age of these patients was 71 years (range 44-77) and clinical features included male gender (86%), B symptomatology (86%), rapidly progressive lymphadenopathy (71%), prior CLL therapy (71%), advanced Ann Arbor stage (86%), marrow involvement with HD (43%), and autoimmune hemolytic anemia (29%). HD was documented by excisional lymph node biopsy in six cases and splenectomy in one. Mixed cellularity HD was shown in six and nodular sclerosis in one. Five of the biopsies revealed intervening areas consistent with small lymphocytic lymphoma. The Sternberg-Reed (SR) cells were CD15+ in 6/7 cases, and Ki-1+ in the 6 patients tested. CD45 and CD20 staining of the SR cells was nonreactive. The median time to development of HD was 45 months (range 0 to 96). The overall responses to different chemotherapy regimens was approximately 25% with only one CR. Six patients have died at 3, 9, 10, 13, 15 and 36 months and one patient is alive with progressive disease at 11 months. Our data suggests that CLL patients have a heightened risk for HD, features of advanced HD on presentation, and a poor response rate with short survival.
We analyzed 144 of 475 previously untreated patients with acute myeloid leukemia (AML, n = 87) and 'high-risk' myelodysplastic syndromes (MDS, n = 57) who failed to achieve a complete remission with fludarabine- and high-dose cytarabine-containing regimens between 1991 and 1994. The AML and MDS groups were comparable with regard to age, major prognostic indicators, supportive care received, type of antileukemia response and causes of death and were considered together. The causes of death of 118 evaluable patients were compared to a series of 123 AML initial remission induction failures previously reported from our institution. The induction failure rate was significantly lower (30 vs 43% P <0.001). We found a significant decrease in fatal infections (autopsied patients, P = 0.001) and a reduction in bacterial (autopsied and non-autopsied patients, P <0.005) but not fungal (non-autopsied patients, P = 0.93; autopsied patients P = 0.15) infections as causes of induction death. Pulmonary hemorrhage was twice as common in the present report (P < 0.005, with pulmonary hemorrhage almost three times as common as fatal cerebral hemorrhage. A comparison restricted to the AML patients in the present study yielded similar results. We conclude that the mortality profile in AML remission induction has undergone substantial changes at our institution since our last report, probably as a consequence of the introduction of new chemotherapy regimens and supportive care modalities.
The purpose of the study was to define the maximally tolerated dose (MTD), major toxicities, and possible antitumor activity of CI-973 a new platinum analogue, in patients with refractory or relapsed acute leukemia. CI-973 was given as a 5-day continuous infusion every 3 to 4 weeks to patients with refractory or relapsed acute leukemia, at doses ranging from 150 mg/m2 to 1350 mg/m2 per course. Thirty-six patients were treated including 18 patients with acute myelogenous leukemia (AML), four with acute lymphocytic leukemia (ALL) and 14 with chronic myelogenous leukemia in blastic phase (CML-BP). Severe gastrointestinal and renal side-effects were the dose-limiting toxicities occurring in four of five patients treated with CI-973 1200 to 1350 mg/m2 per course. At the MTD of 1000 mg/m2 per course, three of 13 patients treated (23%) had moderate to severe nausea and vomiting, three (23%) had moderate diarrhea and one had moderate mucositis. Among 21 patients treated at > or = 1000 mg/m2 (15 AML, 6 CML-BP) no objective complete or partial responses were observed. Twelve of 18 patients (66%) with evaluable marrows on day 14 showed significant suppression of marrow blasts percentage and marrow leukemic infiltrate percentage. Tests for measurement of DNA adduct formation in leukemic cells in vivo after CI-973 therapy, and in vitro following exposure of leukemic cells to CI-973 were developed. This study defined the MTD of CI-973 to be 1000 mg/m2 by continuous infusion over 5 days every 3 to 4 weeks in patients with refractory or relapsed acute leukemia. Gastrointestinal and renal side-effects were dose-limiting. No objective responses were noted in this heavily resistant population. Correlations between CI-973-induced DNA adduct formation and individual patient response to CI-973 will help to define its role in leukemia subsets.
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.
Patients with newly diagnosed acute myelogenous leukemia (AML) with persistent leukemia after their first course (CO1) of induction chemotherapy are generally given a second similar course, although their outcome is known to be worse than CO1 responders even when a complete remission (CR) is achieved. To identify specific patients who should or should not receive a second induction course identical to the first we analyzed outcome in 370 patients with persistent AML after CO1 who received a second identical course. One hundred and forty-two (38%) achieved CR on this course; median subsequent disease-free survival (DFS) in these 142 was 29 weeks and 10% were alive in CR at 5 years. The 5-year DFS of CO2 responders was significantly lower than that of CO1 responders (10 vs 24%, P < 0.001). Logistic regression identified pretreatment cytogenetic abnormalities (except inv 16, t(8;21), or t(15;17)), presence of an antecedent hematologic disorder or secondary AML as each having unfavorable prognostic import similar to the case in untreated patients. Treatment with "high-dose' rather than standard-dose cytarabine increased the probability of 2nd course CR. The occurrence of pneumonia, sepsis, or major hemorrhage were prognostically unfavorable, primarily in the high-dose cytarabine group, and, once in CR, DFS was shorter in this group. Equations predicting probability of 2nd course CR were derived. If validated prospectively these could be used to assign patients to either receive a second course of initial induction therapy or to change to salvage or investigational therapy after the first course. Alternatively, they could be used to stratify patients entering a prospective randomized trial comparing these two strategies.
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Many bone marrow cytogenetic abnormalities in acute myelogenous leukemia (AML) are tumor specific, clonal, nonrandom, and related to prognosis; it has been hypothesized that they may be markers of exposure to etiological agents. A previous report from our institution revealed several such associations; the purpose of the current study was to determine whether previous findings were present in a new group of patients. Subjects included 84 newly diagnosed AML patients (French-American-British M1 and M2); exposure data were gathered using self-report questionnaires at the time of registration. Two sets of comparisons were made: (a) patients with all (AA) or some (AN) cytogenetically abnormal cells versus those with normal karyotypes (NN) and (b) patients with specific abnormalities [-5/5q-, -7/7q-, +8, t(8;21)] versus all others. Odds ratios (ORs) were 4.64 for the association between prior cytotoxic therapy and -5/5q- and 6.38 for the association with -7/7q-, but were <1.00 for +8 and t(8;21). There were no ORs > 2.0 for specific abnormalities in any of the other exposures evaluated (cigarette smoking, alcohol use, occupational exposure to organic chemicals, paints, or pesticides/herbicides), with the exception of exposure to paints and -7/7q- (OR, 7.50). The ORs for AA/AN versus NN patients were 1.43 and 3.81 for smoking and alcohol use, and weak dose-response trends were present. The most consistent positive associations between the two series were for prior cytotoxic therapy (-5/5q-; -7/7q-), cigarette smoking (AA/AN versus NN) and alcohol use (AA/AN versus NN). Reasoning from the known association between prior cytotoxic therapy and -7/7q-, we would have predicted relatively high ORs (> 4.0) if specific abnormalities acted as markers for the exposures assessed, but none were present. However, in both series, AA/AN patients were more likely to smoke and use alcohol than were NN patients, and weak dose-response patterns were present for both. This finding suggests that both smoking and alcohol use may play a role in the pathogenesis of cytogenetic abnormalities in AML-M1/M2; however, the mechanism by which they work and whether they are involved in the etiology of these diseases remain unclear.
We analyzed the 67 of 278 patients with newly-diagnosed AML or 'high-risk' MDS, treated in 1994 and 1995, who developed pneumonia during course 1 of their induction therapy. Pneumonia responded to treatment in 66%, but outcome depended on when pneumonia was diagnosed. Patients with pneumonia diagnosed during week 1 or 2 (group 2 patients) had the lowest response rate (43%). Patients who developed pneumonia in the 3rd week after treatment initiation had the best outcome with all 16 patients recovering. Patients presenting with pneumonia had an intermediate response rate (75%). The different patient groups were comparable with regard to age, underlying disease, prophylactic therapy, and G-CSF application. Although a lower CR rate was not entirely responsible for the lower response rate in group 2, failure to achieve CR predicted unsuccessful treatment of pneumonia in all groups. Fungal pathogens appeared more common in group 2 patients. However, in these patients, administration of amphotericin B was associated with a significantly higher failure rate (15/21 failures vs 2/9 who received no amphotericin B). We conclude that patients who develop pneumonia during week 1 or 2 are a high-risk group, and that use of amphotericin B indicates a particularly poor prognosis, although we present data suggesting that earlier use of amphotericin might be beneficial. Furthermore, since achievement of CR was an important prognostic factor in all groups, WBC transfusions particularly from donors given G-CSF should be considered as a therapeutic option. Finally, since time to failure of induction therapy and time to CR were similar in high-risk patients, new chemotherapy regimens could potentially improve both the CR rate and the outcome of pneumonia.
Fludarabine monophosphate (Fludara) is a purine analogue which entered clinical trials in 1982. Although inactive in solid tumors, Fludara has marked activity in indolent lymphoproliferative disorders. The exact mechanism of action of Fludara is uncertain. Fludara has been established as the most active single agent in chronic lymphocytic leukemia (CLL) in single arm and comparative clinical trials. The activity has been demonstrated in both previously treated and initially treated patients. Marked activity has been noted in patients with low grade lymphoma, in particular, those with a follicular morphology and in Waldenstrom's macroglobulinemia. Combinations of fludarabine with alkylating agents, anthracyclines, and anthraquinones have led to clinically useful combination approaches. The ability of fludarabine to modulate the levels of the triphosphate form of cytosine arabinoside (ara-C) in acute leukemia cells has led to the development of combinations of fludarabine and ara-C. These combinations have demonstrated marked activity in treatment of relapsed and previously untreated patients with acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS). The ability to modulate the activity of pyrimidines and to inhibit repair of DNA damage caused by alkylating agents, anthracyclines, and other DNA active drugs suggest that the future of fludarabine will be in combination approaches to modulate the activity of other agents. These activities may extend its role to use in solid tumors.
Although central nervous system (CNS) leukemic relapse is frequent in adult acute lymphocytic leukemia (ALL), the need for prophylaxis in different risk groups for CNS relapse, the value of high-dose systemic and intrathecal (IT) chemotherapy, and the timing of prophylaxis are not well defined. This analysis was conducted to investigate these questions and to assess the value of a risk-oriented CNS prophylaxis approach. We analyzed the incidence of CNS leukemia after initiation of therapy in patients treated on 4 consecutive trials for adult ALL including different CNS prophylactic modalities. The treatment groups included (1) the program preceeding the vincristine-Adriamycin-dexamethasone (VAD) regimen, with no CNS prophylaxis; (2) the VAD regimen with prophylaxis using high-dose systemic chemotherapy; (3) the modified VAD program with high-dose systemic chemotherapy to all patients and IT chemotherapy for high-risk patients after achieving complete remission; and (4) the hyperCVAD program with early high-dose systemic and IT chemotherapy starting during induction to all patients, with more IT injections (16IT) administered to the high-risk group for CNS relapse compared with the low-risk group (4IT). A total of 391 patients were included, 73 of whom were treated with preVAD, 112 with VAD, 114 with modified VAD, and 92 with hyperCVAD. The overall CNS relapse rates were 31%, 18%, 17%, and 3%, respectively for the 4 groups (P < .001). For the high-risk group for CNS relapse, they were 42%, 26%, 20%, and 2%, respectively (P < .001). The differences in CNS relapse rates in the low-risk group were not statistically significant. At 3 years, the overall CNS leukemia event-free rates were 48%, 76%, and 98%, respectively (P < .001). In the high-risk group, the CNS event-free rates were 38%, 66%, 75%, and 98%, respectively (P < .001); however, there was no difference in the low-risk group. We conclude that (1) high-dose systemic chemotherapy is a useful prophylactic measure; (2) early IT chemotherapy is necessary to reduce the incidence of CNS leukemia overall and in the high-risk group; and (3) a risk-oriented approach is appropriate to tailor the intensity of CNS prophylaxis.
Many patients with chronic lymphocytic leukemia (CLL) achieve remission after treatment with fludarabine chemotherapy. Most of these patients, however, later experience relapse. In addition, immunologic deficits may persist even in patients in complete remission; lymphopenia, predominantly involving the CD4 population, is universal after fludarabine therapy. We used recombinant alpha interferon (IFN-alpha) maintenance therapy in patients with CLL who achieved remission in response to fludarabine therapy to determine its effect on residual disease, assessed by either bone marrow biopsy or flow cytometry, and on immune restoration. Thirty-one patients were treated with IFN-alpha (3 x 10(6) U by subcutaneous injection three times weekly). Twenty-two patients (71%) were in complete remission (CR) and nine (29%) were in partial remission (PR). Of the 22 patients in CR, 21 (95%) had evidence of residual disease at the start of IFN-alpha therapy. Low CD4 levels were noted in 93% of patients, low IgG levels in 45%, and anergy or hypoergy in 52%. Only one patient in PR achieved a CR on IFN-alpha therapy: the only patient who had had no prior fludarabine but had been treated with chlorambucil and prednisone. All patients in CR with minimal residual disease had persistent disease after IFN-alpha treatment. There were no increases in CD4 counts or IgG levels; three patients with borderline responses to skin testing had an increase in the number of positive tests while on IFN-alpha. The time to progression was no different in patients treated with IFN-alpha than in a historical control group of patients who had received no further therapy after fludarabine. In summary, the use of IFN-alpha maintenance did not eradicate residual disease, restore immune function, or prolong remissions in patients with CLL responsive to fludarabine.