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B Clarkson

Publications and source records attributed to B Clarkson.

At least 19 recordsLinked to original sources
PubMed1992

Constitutive expression of p53 protein in enriched normal human marrow blast cell populations.

Previous studies by others using metabolic labeling, cell lysis, and immunoprecipitation have reported elevated levels of p53 protein in blast cells derived from patients with acute lymphoblastic leukemia (ALL) and acute myeloblastic leukemia (AML), whereas p53 protein was not detected in normal light-density bone marrow cells. In this report, using the same detection methods, we confirm the negligible expression of p53 protein in normal light density marrow cells. However, we find clearly significant levels of p53 protein expression in enriched normal human marrow blast populations. Furthermore, using a panel of p53 specific monoclonal antibodies, we find the p53 protein constitutively synthesized by normal marrow blasts has the immunologic phenotype identified by PAb240 that reportedly recognizes a common conformational-dependent epitope on mutant p53. We have also found that the p53 immunologic subclass identified by PAb240 exists in normal human circulating lymphocytes either resting, serum starved, or PHA activated. In summary, it is clear that (1) normal marrow blast populations provide the appropriate control for assessing the levels of p53 protein expression in leukemic blast cells; and (2) PAb240 cannot be used to distinguish p53 mutated at the DNA level from normal p53 in fresh human hematopoietic cells.

Antibodies, Monoclonal↗
PubMed1992

Reasons that patients with acute myelogenous leukemia do not undergo allogeneic bone marrow transplantation.

BACKGROUND: Numerous reports suggest that allogeneic bone marrow transplantation prolongs the survival of adult patients with acute myelogenous leukemia (AML) in first remission. However, it is unclear how many such patients actually undergo this procedure. METHODS: We reviewed the case records of 350 consecutive adult patients with AML treated with chemotherapy at a single institution from 1979 (when the policy of offering allogeneic transplantation to all such patients in first remission was introduced) through 1990. The criteria for exclusion before transplantation included age greater than 40 and, beginning in 1984, a diagnosis of acute promyelocytic leukemia. RESULTS: One hundred forty-two patients (41 percent of the study population) were 40 years of age or under. HLA testing was performed for 120 of these patients (85 percent). Sixty-seven patients (47 percent) had an HLA-identical sibling as a potential donor. One hundred three patients (73 percent) entered remission during treatment according to one of five chemotherapy protocols. Of the 52 patients who both entered remission and had an HLA match, 30 underwent transplantation while they were in first remission. These 30 patients constituted 21 percent of all study patients 40 years old or under, 29 percent of all patients 40 or under who entered remission, 45 percent of all patients with an HLA match, 58 percent of all patients who had both a remission and a match, and 9 percent of all patients treated according to a protocol. Among patients with a match who did not undergo transplantation, those with primary refractory disease were the largest subgroup. CONCLUSIONS: These findings suggest that allogeneic bone marrow transplantation is performed in less than 60 percent of adult patients with AML who are potentially eligible for the procedure.

Adult↗
PubMed1992

Autologous bone marrow transplantation for acute myelogenous leukemia using 4-hydroperoxycyclophosphamide and VP-16 purged bone marrow.

Thirty adult patients with acute myelogenous leukemia (AML) in remission were treated with hyperfractionated total body irradiation, VP-16, and cyclophosphamide followed by infusion of autologous bone marrow purged with 4-hydroperoxycyclophosphamide and VP-16. Fifteen patients were transplanted in first remission (R1), 13 in second remission (R2), and two in third remission (R3). All patients had hematopoietic engraftment. The median time to achieve a white blood cell count of 1.0 x 10(9)/l and a neutrophil count of 500 x 10(6)/l was 32 days. The median time to achieve an unsupported platelet count of 50 x 10(9)/l was 70 days. There were four transplant-related deaths, all in patients in R2. Ten patients have relapsed, including both patients transplanted in R3. The disease-free survival (DFS) of all patients is 52%, median follow-up not yet reached. Although the number of patients in each group is small and follow-up is limited, there is a trend toward improved actuarial DFS in patients transplanted in R1 compared with patients transplanted in R2 (72 vs 39%; p = 0.081). Use of VP-16 in the conditioning regimen as well as in the purging procedure is feasible in the treatment of patients with AML.

Adult↗
PubMed1991

Effect of tamoxifen on cell lines displaying the multidrug-resistant phenotype.

We examined the effect of tamoxifen (Tmx), verapamil, and daunorubicin (DNR) in two cell lines that displayed the multidrug-resistant (MDR) phenotype and used laser flow cytometry to quantitate intracellular DNR content. In the vinblastine-resistant human lymphoblastic lymphoma cell line CEM-VBL, simultaneous incubation of DNR with Tmx 10 mumol/L or Tmx 50 mumol/L increased intracellular DNR fluorescence in a dose-dependent manner and demonstrated an uptake pattern similar to that seen with DNR and verapamil. Similar results were obtained in the vincristine-resistant human myeloid leukemia cell line HL-60/RV+. Cellular retention of DNR was also measured in both cell lines and results suggested that continuous exposure of the cells to Tmx resulted in higher intracellular DNR content compared with cells resuspended in fresh medium. No effect of Tmx or verapamil was observed in the drug-sensitive parent cell lines CEM or HL-60. Clonogenic experiments were then performed to determine whether Tmx was itself inhibitory to cell growth or whether Tmx potentiated DNR cytotoxicity. Tmx 10 mumol/L did not significantly inhibit either CEM-VBL or HL-60/RV+ cells after a 3-hour exposure followed by culture in methylcellulose. Tmx 50 mumol/L was significantly more inhibitory in both cell lines. However, cells that had been incubated with DNR and Tmx 10 mumol/L demonstrated a marked increment in growth inhibition compared with cells that had been incubated with DNR alone or Tmx 10 mumol/L alone. Based on the data presented here, we suggest that clinical testing of Tmx and DNR be pursued in the setting where MDR may play a role.

Cell Division↗
PubMed1991

Co-detection of chimeric bcr/abl (target) and beta-actin (control) messenger RNA in individual CFU-GM colonies derived from CML patients using the polymerase chain reaction.

In order to quantitate the magnitude of the normal and Philadelphia (Ph') chromosome-positive(+) progenitor cells for various research and clinical settings/studies, we have applied the highly sensitive polymerase chain reaction (PCR) for examining the cells contained in individual hematopoietic colonies for chimeric bcr/abl mRNA, a specific molecular marker for chronic myelogenous leukemia (CML). Thus, individual 14-day CFU-GM colonies, obtained by growth of bone marrow cells from CML patients were removed from methylcellulose cultures and total RNA from each colony was isolated. First-strand complementary DNAs (cDNA) corresponding to all mRNAs in the sample were obtained by using random hexamers in a reverse transcription (RT) reaction. cDNA then served as the substrate in the PCR. To ensure the integrity of the RNA extracted from each colony, beta-actin and bcr/abl cDNA sequences were amplified in the same reaction vessel. Using this method, we have examined the colonies grown from three CML patients and found that 5 out of 5, 9 out of 9 and 8 out of 9 colonies contained a bcr/abl transcript. This method is simple, highly sensitive and should facilitate studies comparing the expression of various oncogenes in normal and leukemic hematopoietic progenitor cells.

Actins↗
PubMed1991

Diffuse large cell lymphoma. Prognostic factors with treatment.

Five successive chemotherapy protocols for stages II, III and IV diffuse large cell lymphoma (DLCL) have resulted in identical overall survivals. Between 35% to 45% of patients survived. In a multivariate analysis employing the Weibull model 3 factors were associated with shortened survival: bulky mediastinal and/or retroperitoneal disease, elevated serum LDH and advanced age. In young patients with bulky mediastinal and/or retroperitoneal disease and high serum LDH, autologous bone marrow transplantation following high dose chemotherapy and radiation therapy (RT) as part of the initial treatment have produced more promising results. In a randomized trial, a significantly longer disease-free survival was found for patients with stages I or IE diffuse lymphomas with RT followed by adjuvant chemotherapy than with RT alone.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Retinoic acid in acute promyelocytic leukemia: the promise and the paradox.

Acute promyelocytic leukemia (APL) is a particularly virulent subtype of acute myeloid leukemia that is associated with a specific chromosomal translocation, t(15;17). Patients with APL are currently being managed with cytolytic chemotherapy (usually an anthracycline in combination with arabinosylcytosine), a treatment that can induce complete remissions in 65% or more of patients and probably cure 15% or more. Exciting new clinical observations have shown that patients with APL also respond extremely well to treatment with all-trans retinoic acid, an agent which induces the leukemic promyelocytes to undergo maturation and lose their ability to proliferate. Retinoic acid by itself is not curative, but by combining it with cytolytic chemotherapy, it may be possible to cure the majority of patients with this previously fatal leukemia. Interestingly, independent molecular studies have recently revealed that the breakpoint of t(15;17) lies within the gene encoding the retinoic acid receptor-alpha (RAR-alpha) on chromosome 17q21, and that patients with APL express aberrant forms of the RAR-alpha transcript. This convergence of clinical and molecular observations, though fortuitous, is extremely important because it represents the first example of a selective form of treatment for a human leukemia that is related to a specific genetic abnormality.

Humans↗
PubMed1990

Incidence of response and long-term follow-up in patients with hairy cell leukemia treated with recombinant interferon alfa-2a.

Thirty-five evaluable patients with hairy cell leukemia (HCL) were treated with recombinant interferon alfa-2a (rIFN-alpha 2a), given at a dose of 3 X 10(6) units (U) intramuscularly (IM) daily for 6 months followed by 3 X 10(6) U IM three times a week for an additional 18 months in a single institution study. All treatment was stopped after 24 months. Sixty-nine percent of patients achieved a partial response, 11% a minor response, and 3% (one patient) had stable disease. Six patients (17%) did not respond to rIFN-alpha 2a. Two patients (6%) achieved a response but later progressed on treatment. A total of 23 patients completed 2 years of treatment and are evaluable for long-term follow-up at a median of 20 months postcompletion of therapy (range 9 to 32 months). Eleven patients (48%) have had progression of their disease at a median of 10 months (range .5 to 25 months) after treatment was discontinued. Statistical analysis of pretreatment patient characteristics did not reveal any factor(s) associated with a high probability of responding to rIFN-alpha 2a; however, analysis of post-treatment variables measured after 2 years of treatment suggested that a low platelet count was associated with a high rate of disease progression. These findings are compared with other published trials using rIFN-alpha 2b, a similar but not identical rIFN preparation. We conclude that while rIFN-alpha 2a has a high overall response incidence, the rate of disease progression after therapy is discontinued approaches 50%, and that a subset of patients can be identified who are at high risk for recurrence after completing 2 years of treatment.

Adult↗
PubMed1990

Importance of long-term follow-up in evaluating treatment regimens for adults with acute lymphoblastic leukemia.

During the past 20 years, we have treated 250 previously untreated adults (greater than age 15 years) with acute lymphoblastic leukemia (ALL) with five successive multidrug protocols: L2, L10, L10M, L17/17M, and L20. The L10 and L10M protocols had the highest percentage of long-term (greater than 5 years) remissions (52% and 40% respectively) compared with the L2 and more recent protocols (24%-32%); this is partly attributable to a greater prevalence of adverse risk factors among the latter protocols. The overall long-term survival of the first 199 patients with minimum 3 years follow-up is now 31%, with 35% of the 163 patients achieving complete remission (CR) remaining free of relapse for greater than 5 years. The disease-free survival of the 163 patients reaches a plateau of 33% after 6 years. The percentages of patients subsequently relapsing after remaining in continuous CR for 1.5, 3, and 5 years are 42%, 28%, and 6%, respectively; no relapses have yet occurred after 6 years in this series. Postrelapse survival improved progressively with longer duration of first remission. The results of treatment in second or later remission with either chemotherapy or bone marrow transplantation (BMT) were unsatisfactory and there were only a few long-term survivors. Recently we have attempted to select patients at highest risk of early relapse for BMT in first remission, but the number of eligible patients actually having BMTs has been low for a variety of reasons, including early death, failure to reach CR, early relapse, patient refusal, or medical contraindications.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Photoradiation methods for purging autologous bone marrow grafts.

The potential of various photoradiation therapy for the in vitro purging of residual tumor cells from autologous bone marrow (BM) transplants is discussed in this paper. The results with fluorescent dyes, Dihematoporphyrin Ether (DHE) and Merocyanine-540 (MC-540) are detailed. Following photoradiation of cells with white light, both DHE and MC-540 showed high cytocidal activity towards lymphoid and myeloid neoplastic cells, but had significantly less effect on normal granulocyte-macrophage (CFU-GM), erythroid (BFU-E) and mixed colony-forming (CFU-GEMM) progenitor cells. Acute promyelocytic leukemia (HL-60), non-B, non-T, cALLa positive acute lymphoblastic leukemia (Reh), and diffuse histiocytic B-cell lymphoma (SK-DHL-2) cell lines were exposed to different drug concentrations in combination with white light at a constant illumination rate of 50,000 lux. With DHE doses varying from 2.0 to 2.5 ug/ml and MC-540 concentrations of 15 to 20 ug/ml, clonogenic tumor cells could be reduced by more than 4 logs, when treated alone or in mixtures with normal irradiated human marrow cells. However, preferential cytotoxicity towards neoplastic cells was highly dependent on the mode of light activation. MC-540 had no substantial effect on malignant lymphoid (SK-DHL-2) and myeloid (HL-60) cells, and on normal marrow myeloid (CFU-GM) precursors, when the drug incubation was performed in the dark and followed by light exposure of washed cells. Equal doses of MC-540 (15-20 ug/ml) could preferentially eliminate tumor cells under conditions of simultaneous light and drug treatment (30 minutes at 37 degrees C). Using DHE (2.5 ug/ml), 29.3%, 46.8%, and 27.5% of normal marrow CFU-GM, BFU-E, and CFU-GEMM, respectively, were spared, following sequential drug and light exposure of cells, while simultaneous treatment reduced both normal (CFU-GM) and neoplastic cells below the limits of detection. The data from various centers is briefly discussed with special emphasis on clinical trials. Our results provide a useful model for leukemia and lymphoma cells and suggest that these phototherapy experiments can be implemented into clinical trials.

Bone Marrow↗
PubMed1989

Increased density of ecto 5' nucleotidase antigen on leukemic T cells from patients with cutaneous T-cell lymphoma and adult T-cell leukemia/lymphoma.

Malignant CD4+ T cells in adult T-cell leukemia/lymphoma (ATL) and cutaneous T-cell lymphoma (CTCL) express a number of cell surface molecules that are upregulated on normal T cells activated by foreign antigen. In this report we describe an interesting exception to the parallel phenotypic features of activated T cells and malignant CD4+ T cells. A monoclonal antibody (MoAb; termed 27.2) that was raised to HTLV-1+, CD4+25+ leukemic T cells stained weakly 25% of peripheral T cells, including approximately 50% of CD8+ T cells and 20% of CD4+ T cells. Flow cytometry analysis indicated that the surface density of the 27.2 antigen was unchanged or diminished when normal T cells were activated by antigen. However, 3/4 Sezary cases and 4/8 cases of ATL had relatively high densities of the 27.2 antigen. Immunoprecipitation and sodium dodecylsulfate polyacrylamide gel electrophoresis of the NP-40-solubilized membranes of surface-iodinated ATL cells indicated that MoAb 27.2 reacted with a 75 Kd molecule. The size and distribution of the 27.2 antigen on T cell subsets suggested that it might be the enzyme ecto-5' nucleotidase (NT), a phosphatidylinositol-linked enzyme that catalyzes dephosphorylation of monophosphate nucleotides to their respective nucleosides. This was confirmed by demonstrating that lymphocyte ecto-5'NT activity was blocked partially and inhibited completely by preincubating cells with MoAb 27.2 for 1 hour at 4 degrees C and 24 hours at 37 degrees C, respectively. When used with a second MoAb (27.1) to a novel T cell activation antigen found on all CTCL and ATL leukemias examined, 27.2 was found to discriminate between normal and leukemic T cells in two patients with ATL. These studies suggest that ecto-5'NT has diagnostic value in T cell malignancies and may be aberrantly expressed in some cases of ATL and CTCL.

5'-Nucleotidase↗
PubMed1989

Total lymphoid irradiation, high-dose chemotherapy and autologous bone marrow transplantation for chemotherapy-resistant Hodgkin's disease.

Seventeen patients with advanced stage Hodgkin's disease who relapsed or failed to respond to multiple regimens of combination chemotherapy (mostly Mechlorethamine, Vincristine, Procarbarzine, Prednisone and Adriamycin, Bleomycin, Vinblastine, Dacarbazine) were treated with accelerated hyperfractionated total lymphoid irradiation (TLI) and high-dose chemotherapy followed by autologous bone marrow transplantation (AuBMT). Candidates for the protocol did not have prior radiation therapy and had no evidence of bone marrow involvement. Their bone marrow was initially harvested and cryopreserved. The treatment protocol consisted of reinduction with conventional doses of combination chemotherapy followed by boost local field irradiation to areas of residual disease (1500 cGy within 5 days) and total lymphoid irradiation (2004 cGy given in 12 fractions of 167 cGy each t.i.d. delivered within 4 days). The patients were treated with Etoposide (250 mg/m2/day I.V. X 3 days) and high-dose Cyclophosphamide (60 mg/kg/day I.V. X 2 days). Cryopreserved (unpurged) autologous bone marrow was infused 48 hr after completion of chemotherapy. Of the 17 patients treated, four were in relapse and 13 refractory to multiple regimens of combination chemotherapy. Four patients died during the immediate peritransplant period (2--septicemia, 2--pulmonary complications). Of the 13 surviving patients, 12 entered a complete remission and one had a partial remission and died of disease 6 months later. One patient relapsed 5 months after treatment and is currently alive with disease. Eleven patients (65%) are alive with no evidence of disease 4-35 months (median 20 months) following completion of therapy. Treatment with this protocol results in a high rate of complete remission and a potential for long-term disease-free survival in previously unirradiated patients with advanced stage refractory or relapsed Hodgkin's disease who have exhausted conventional modes of chemotherapy.

Adult↗
PubMed1989

Immunophenotypic demonstration of two natural killer surface markers, H25 and H366, on fresh human leukemic cells.

Using a modified alkaline-phosphatase/antialkaline-phosphatase method for phenotyping fresh human leukemias, we could demonstrate peripheral blood and bone marrow-derived blast cells to specifically react with two monoclonal antibodies (MoAbs), H25 and H366, previously shown to recognize natural killer cells, activated T lymphocytes and a proportion of normal hematopoietic precursor cells. MoAbs H25 and H366 were found to identify the majority of leukemic cells in patients presenting with T-ALL, LGL leukemia, pre-B-ALL, CML, and AML, respectively.

Animals↗