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Biomedical subjects

S F Williams

Publications and source records attributed to S F Williams.

At least 73 records · Page 4Linked to original sources
PubMed1992

Characterization of chemotherapy mobilized peripheral blood progenitor cells for use in autologous stem cell transplantation.

Twenty patients were treated with chemotherapy to mobilize progenitors into the blood. Peripheral blood stem cells were quantitated in peripheral blood or leukapheresis products using colony assays and flow cytometric measurement of CD34+ cells. In four patients where complete sets of serial samples were obtained, the appearance of CD34+ cells preceded the increase in CFU-GM by 24-48 h. Peak levels of CD34+ cells ranged from 0.6-5% and coincided with the peak increase in CFU-GM. Mobilized CD34+ cells contained subsets expressing CD33, CD13, CD45RA, CD38, HLA-DR, CD61 and CD41. Subsets of CD34+ cells expressing CD33, CD13, or CD45RA represent committed myeloid progenitors. In contrast to bone marrow CD34+ cells, few mobilized CD34+ cells expressed CD71, CD7, CD19 or CD10. Prompt engraftment of granulocytes greater than 500 x 10(6)/l at a median of 13 days and platelets greater than 50 x 10(9)/l at a median of 15 days was observed in patients reconstituted with mobilized cells. These data indicate that CD34+ cells mobilized during recovery from chemotherapy are predominantly myeloid in phenotype and contain few actively proliferating cells or cells with lymphoid phenotypes.

Antigens, CD↗
PubMed1992

Phase I study of busulfan, cyclophosphamide, and timed sequential escalating doses of cytarabine followed by bone marrow transplantation.

In both animal models and human studies in leukemia, residual disease on day 8 following myelosuppressive therapy is in a proliferative phase and therefore may be sensitive to the S-phase specific drug cytarabine. Based on this concept, 17 patients with refractory or relapsed leukemia or lymphoma undergoing either autologous or allogeneic bone marrow transplantation (BMT) were treated on a Phase I protocol using high doses of busulfan (16 mg/kg, days -10, -9, -8, -7) and cyclophosphamide (120 mg/kg, days -6, -5) followed by escalating doses of a 48-h continuous infusion of cytarabine (starting dose 1000 mg/m2/48 h, days -3, -2). Ten patients received autologous transplants (two with Hodgkin's disease, seven with non-Hodgkin's lymphoma, one with chronic myelogenous leukemia (CML) in blast phase). Seven received allogeneic BMT (two with refractory acute myelocytic leukemia (AML), one with refractory acute lymphoblastic leukemia (ALL) undergoing a second BMT, one with Burkitt's-type leukemia, one with ALL in fifth relapse and two with CML in accelerated/blast phase). Two of these patients received a T cell-depleted haploidentical transplant. The maximum tolerated dose of cytarabine was 1500 mg/m2/48 h; a pulmonary syndrome including dyspnea, hypoxemia, and interstitial infiltrates which responded to aggressive diuresis was the dose limiting toxicity. Of the 10 patients who received cytarabine doses of 2000 or 2500 mg/m2/48 h, five patients developed adult respiratory distress syndrome (ARDS) with three patients requiring intubation; two recovered. Of the nine patients with lymphoma, seven responded with complete tumor clearance (CTC) with two patients tumor-free 13 and 15 months post-BMT, one remained refractory and one died too early to evaluate (TETE).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Biosynthetic thiolase from Zoogloea ramigera. Evidence for a mechanism involving Cys-378 as the active site base.

Biosynthetic thiolase from Zoogloea ramigera was inactivated with a mechanism-based inactivator, 3-pentynoyl-S-pantetheine-11-pivalate (3-pentynoyl-SPP) where K1 = 1.25 mM and kinact = 0.26 min-1, 2,3-pentadienoyl-SPP obtained from nonenzymatic rearrangement of 3-pentynoyl-SPP where K1 = 1.54 mM and kinact = 1.9 min-1 and an affinity labeling reagent, acryl-SPP. The results obtained with the alkynoyl and allenoyl inactivators are taken as evidence that thiolase from Z. ramigera is able to catalyze proton abstraction uncoupled from carbon-carbon bond formation. The inactivator, 3-pentynoyl-SPP and the affinity labeling reagent, acryl-SPP, trap the same active site cysteine residue, Cys-378. To assess if Cys-378 is the active site residue involved in deprotonation of the second molecule of acetyl-CoA, a Gly-378 mutant enzyme was studied. In the thiolysis direction the Gly-378 mutant was more than 50,000-fold slower than wild type and over 100,000-fold slower in the condensation direction. However, the mutant enzyme was still capable of forming the acetyl-enzyme intermediate and incorporated 0.81 equivalents of 14C-label after incubation with [14C]Ac-CoA for 60 min. The reversible exchange of 32P-label from [32P]CoASH into Ac-CoA, catalyzed by the Gly-378 mutant enzyme, proceeded with a Vmax (exchange) 8,000-fold less than the wild type enzyme but at least 10-fold faster than the overall condensation reaction. These data provide evidence that Cys-378 is the active site base.

Acetyl-CoA C-Acetyltransferase↗
PubMed1991

Paradoxical relationship between acetylator phenotype and amonafide toxicity.

Patients receiving the investigational antineoplastic agent amonafide underwent prospective determination of acetylator phenotype with use of caffeine as a test drug. Fast acetylators of caffeine had significantly greater toxicity (myelosuppression) after amonafide treatment than slow acetylators, presumably because of greater conversion of amonafide to the active acetylated metabolite. Furthermore, the estimated area under the plasma concentration-time curve of amonafide was significantly greater in the fast acetylators, indicating that the total plasma clearance was paradoxically lower in this group. It is hypothesized that this paradox is attributable to competition for oxidation of amonafide by its acetylated metabolite (parallel pathway interaction). Pretreatment white blood count and patient age were also independent predictors of leukopenia. In addition, it was noted that the ratio of actual to ideal body weight was significantly higher in the fast acetylators. Studies are in progress to determine the optimal amonafide dose in both acetylator subgroups.

Acetylation↗
PubMed1990

High-dose tri-alkylator chemotherapy with autologous stem cell rescue in patients with refractory malignancies.

Forty patients with refractory solid tumors or non-Hodgkin's lymphoma were treated with high-dose cyclophosphamide, thiotepa, and carmustine (BCNU), followed by autologous stem cell rescue, in a phase I dose escalation study. The dose-limiting toxic effect was delayed drug-induced pulmonary disease, seen in three patients who received 660-750 mg of BCNU/m2 in combination with cyclophosphamide and thiotepa. The early death rate due to toxic effects was 20%; all deaths were attributed to sepsis or respiratory failure. The overall response rate was 63%. The median time to disease progression was 14 weeks. Although this regimen provided effective cytoreduction, its use in heavily pretreated patients with bulky disease is of limited value.

Adult↗
PubMed1990

Peripheral blood-derived stem cell collections for use in autologous transplantation after high dose chemotherapy: an alternative approach.

Peripheral blood-derived hematopoietic stem cells (PBHSC) can be utilized to reconstitute hematopoiesis in patients after high dose myeloablative chemotherapy. We have performed PBHSC reinfusion in 18 patients who have or had a history of tumor involving the bone marrow or a hypocellular bone marrow. The PBHSC were collected by continuous flow leukapheresis and subsequently cryopreserved. A median of 31.9 X 10(9) (range 18 X 10(9)-67.2 X 10(9)) mononuclear cells or a median of 4.85 X 10(8) mononuclear cells/kg (range 2.7 X 10(8)-11.0 X 10(8)) were collected. Fifteen patients had in vitro assays of granulocyte-monocyte colony-forming cells (CFU-GM) performed with a median of 2.7 X 10(4) (range 0-11.5 X 10(4)) CFU-GM/kg. To date, of the 18 patients collected, all have undergone high dose chemotherapy and PBHSC reinfusion. For the evaluable patients, granulocyte recovery (greater than 500 X 10(6)/ml) has occurred in a median of 15 days and platelet recovery (greater than 50 X 10(9)/ml without transfusion support) has occurred in a median of 43 days. Four patients have had prolonged thrombocytopenia and still require platelet transfusion at 80+, 97+, 124+, and 270+ days. PBHSC collection is safe and effective for hematopoietic reconstitution after high dose chemotherapy in the majority of patients; however incomplete hematopoietic reconstitution has been observed in 4/18 evaluable patients. This procedure requires further investigation.

Adult↗
PubMed1990

A phase I-II study of high-dose cyclophosphamide, thiotepa and escalating doses of mitoxantrone with autologous stem cell rescue in patients with refractory malignancies.

Twenty-five patients with refractory solid tumors were treated with high-dose cyclophosphamide, thiotepa and mitoxantrone followed by autologous stem cell rescue in a phase I dose escalation study. The dose-limiting toxic effect was mucositis at 60 mg/m2 of mitoxantrone in combination with cyclophosphamide and thiotepa. The early death rate due to toxic effects was 24%; all deaths were attributed to infections. Hematopoietic recovery was quite prolonged with median times to granulocyte (greater than 500 x 10(6)/l) and platelet (greater than 50 x 10(9)/l) recovery at 58 and 148 days, respectively. The overall response rate was 56%. The median time to progression was 14 weeks. Thus, this regimen has activity against refractory malignancies although early and prohibitive toxicity occurs when mitoxantrone is escalated in this setting.

Actuarial Analysis↗
PubMed1990

Patients at increased risk for late engraftment after transplantation: a novel method for their identification.

The time to platelet engraftment (platelets greater than 50 x 10(9)/l for 3 successive days without transfusions) is a major endpoint in treatment regimens of high dose chemotherapy and autologous stem cell rescue. A number of transplanted patients die before recovery of platelets. To include such patients appropriately in an analysis to identify prognostic factors for engraftment, a proportional odds model was employed. The outcome measure was a categorization of patients into four levels based on time to engraftment: early (0-40 days), intermediate (41-70 days), late (greater than 70 days) or died without engraftment. Of 45 women with advanced breast cancer who underwent high dose chemotherapy and autologous transplantation, there were: 10 early, 11 intermediate and eight late engrafters and 16 who died before platelet engraftment. Based on the proportional odds model applied to these data, four significant and independent prognostic factors for later or non-engraftment were revealed: lower numbers of mononuclear cells/kg harvested (p = 0.002), lower serum albumin level (p = 0.003), prior cisplatin chemotherapy (p = 0.006), and the existence of bone marrow malignancy (p = 0.025).

Adult↗
PubMed1990

The role of bone marrow transplantation in the non-Hodgkin's lymphomas.

In a significant fraction of patients with NHL, disease develops that is resistant to conventional chemotherapy. Experience using high-dose chemotherapy, with or without TBI, and BMT is expanding. Remissions can be achieved in many patients with refractory NHL in particular those patients with tumors that are still chemosensitive. High-dose chemoradiotherapy regimens are toxic and require extensive supportive care. Relapse frequently occurs in areas of previous disease, suggesting failure of the conditioning regimen rather than that an infusion of occult tumor cells in the autologous bone marrow had occurred. Thus, the role of marrow purging in this therapy needs to be further evaluated and compared with findings involving nonpurged marrow reinfusion. It is also important to evaluate the effects of more vigorous attempts at cytoreduction of bulky disease prior to high-dose therapy and BMT. Potential areas for development include the use of this modality as intensification therapy following conventional therapy in patients with intermediate or high-grade NHL with poor prognostic features. Toxicity can be decreased and efficacy increased only if therapy is administered to patients who have not been heavily pretreated and who have lower tumor burden and a good performance status. The role of high-dose chemotherapy and BMT in the nodular lymphomas is not known at this point and requires further investigation. Finally, high-dose therapy with BMT has a definite role in salvaging patients with malignant lymphomas. Many issues need to be resolved, including (1) the optimal timing of this approach, (2) the optimal conditioning regimen, and (3) the need for purging autologous bone marrow prior to reinfusion. The past 10 years have led to significant gains. During the next 10 years, it may be possible to refine this therapy and find solutions to the above issues.

Antineoplastic Agents↗
PubMed1989

Plasma pharmacokinetics of high-dose oral melphalan in patients treated with trialkylator chemotherapy and autologous bone marrow reinfusion.

The pharmacokinetics of melphalan following high-dose p.o. administration were determined in 17 patients with various malignancies for the purpose of assessing interpatient and intrapatient pharmacokinetic variability. All patients underwent bone marrow harvest on day -8 (relative to bone marrow reinfusion). On days -7, -6, and -5, melphalan was given p.o. and the dose was escalated on each cohort consisting of at least 3 patients (beginning at 0.75 mg/kg). On days -6, -4, and -2, cyclophosphamide at 2.5 g/m2 and thiotepa at 225 mg/m2 were given i.v. On day -7 the peak melphalan concentration was 1.64 +/- 0.89 (SD) microM with a terminal half-life of 1.56 +/- 0.86 h. The area under the plasma concentration time curve (AUC) and oral clearance were 217.9 +/- 115.1 microM/min and 30.2 +/- 14.2 ml/min/kg. There was only a moderate correlation between the melphalan dose and both the peak concentration (r = 0.50, P less than 0.05) and AUC (r = 0.64, P less than 0.01) over the dosage range of 0.75-2.5 mg/kg. There was a trend towards greater interpatient variability in peak concentration, AUC, and oral clearance observed at the higher doses of melphalan. Analysis of intrapatient pharmacokinetic variability in 8 patients showed a significant difference between the doses given on days -7 and -5 in the peak concentration (2.09 versus 1.07 microM, P = 0.02), AUC (264.9 versus 134.8 microM/min, P = 0.01), and oral clearance (25.1 versus 53.1 ml/min/kg, P = 0.05) but no significant difference in the time to peak and terminal half-life. We conclude that there is marked interpatient and intrapatient variability in melphalan pharmacokinetics following high-dose p.o. administration. The data are consistent with saturable absorptive pathways for melphalan, which might be especially sensitive to concurrent high-dose chemotherapy.

Absorption↗
PubMed1989

High-dose, multiple-alkylator chemotherapy with autologous bone marrow reinfusion in patients with advanced non-small cell lung cancer.

Fifteen patients with Stage IV lung cancer both untreated and previously treated were enrolled into a high-dose chemotherapy program with multiple alkylating agents and autologous bone marrow reinfusion. Eight patients received cyclophosphamide at 7.5 gm/m2 over 3 days with thiotepa escalated from levels of 1.8 mg/kg to 6.0 mg/kg over 3 days. Seven patients received the above dose of cyclophosphamide plus thiotepa at 675 mg/m2 and oral melphalan escalated from levels of 0.75 mg/kg to 2.5 mg/kg over 3 days. Both regimens are part of larger Phase I-II clinical studies. The median time to recovery of more than 500 granulocytes and more than 50,000 platelets per microliter was 16 and 27 days, respectively. Two patients died as a consequence of severe, overwhelming infections during their period of aplasia. Of the 13 evaluable patients, no patients achieved a complete response and seven patients (47%) obtained a partial response. The median duration of response was 12 weeks. Other nonhematologic toxicities included nausea/vomiting, diarrhea, mucositis, skin rash, hemorrhagic cystitis, and cardiomyopathy. Since there are substantial toxicities associated with high-dose chemotherapy and responses of such brief duration, further investigation with these drug combinations is not warranted.

Adult↗
PubMed1989

High-dose consolidation therapy with autologous stem cell rescue in stage IV breast cancer.

We designed a phase II study to determine whether induction chemotherapy (CT) consisting of leucovorin, vincristine, methotrexate, doxorubicin, and cyclophosphamide (LOMAC) followed by high-dose intensification chemotherapy (ICT) with cyclophosphamide, thiotepa, and autologous stem cell rescue (ASCR) could increase the complete response (CR) rate and survival in women with stage IV breast cancer. Twenty-nine women were enrolled on study; 16 patients had received prior adjuvant chemotherapy and no patient had received chemotherapy for stage IV disease. Two patients were found to be ineligible and excluded from further analysis. Of the 27 patients treated, four (15%) obtained a CR and 15 (56%) a partial response (PR) after LOMAC induction, for an overall response rate of 70%. Of the 22 patients treated with ICT, 12 patients had a CR, and nine were in PR after induction and converted to CR after ICT. The toxicities included nausea/vomiting, mucositis, diarrhea, dermatitis, alopecia, and infections secondary to neutropenia. The 1-year survival is 60%; the median has not yet been reached. The time to treatment failure for patients on study is 10 months. The treatment approach of ICT and ASCR following induction chemotherapy can lead to an improved CR rate in stage IV breast cancer. How this increased CR rate leads to a prolonged disease-free survival requires further follow-up.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

High dose chemotherapy with autologous hematopoietic stem cell support in the treatment of refractory stage IV breast carcinoma.

Fourteen patients with refractory metastatic breast cancer were treated with high dose chemotherapy and autologous hematopoietic stem cell rescue. All patients received cyclophosphamide (7.5 g/m2 over 3 days) and thiotepa (150-225 mg/m2 over 3 days), three patients in addition received melphalan (4.5 mg/kg), and seven patients received carmustine (150-562 mg/m2). Toxicities included pancytopenia, infection, hemorrhagic cystitis, skin rash, nausea, vomiting, diarrhea, and mucositis. There was one toxic death secondary to sepsis and ventricular tachycardia. The overall response rate was 77% including a 15% complete response rate. The overall median survival for all patients was 6.0 months (range 2-22 months). The median survival for nonresponders was 3.5 months. The median duration of response was 89 days (range 40-262). In our experience high dose chemotherapy with autologous stem cell reinfusion produces a high response rate in refractory breast cancer. However, because of the short duration of response and overall survival, we feel this type of therapy should be utilized earlier in the course of disease.

Adult↗
PubMed1989

The staging of Hodgkin's disease.

The approach to staging patients with Hodgkin's disease has changed over the last 20 years. Although careful physical examination, chest radiograph, and bipedal lymph-angiogram remain the mainstays of the clinical evaluation, computed tomography (CT) scanning of the chest and abdomen is rapidly gaining acceptance as a useful ancillary procedure. In addition, the initial enthusiasm for the staging laparotomy and splenectomy as a necessary part of the staging evaluation is now coming into question. Recent studies raise legitimate concerns about this procedure's overall impact upon survival as well as the potential long-term consequences of splenectomy. Select situations do exist, however, where a staging laparotomy remains appropriate. An approach to the staging of newly diagnosed Hodgkin's disease is suggested and supported by recent studies of this disease.

Abdomen↗