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Biomedical subjects

K D Bagshawe

Publications and source records attributed to K D Bagshawe.

At least 55 records · Page 3Linked to original sources
PubMed1991

Correlation of plasma methotrexate concentration with human chorionic gonadotropin and therapeutic response to low-dose methotrexate-citrovorum factor in low-medium-risk gestational trophoblastic tumors.

Seventeen patients with low- or medium-risk gestational trophoblastic tumors (GTT) and one patient with a placental-site trophoblastic tumor were treated according to an 8-day schedule of low-dose methotrexate (LDMTX) alternating with citrovorum factor (CF). Plasma concentrations of methotrexate (MTX) were correlated with serum human chorionic gonadotropin (hCG) levels and clinical response. After an intramuscular dose of 50 mg, plasma MTX levels rose rapidly, reached a peak concentration of 5.8 x 10(-6) M/liter at 1 hour and persisted above 10(-6) M/liter normally considered inhibitory for DNA synthesis, for approximately 7 1/2 hours. Rapid plasma clearance followed with plasma levels reaching 5-7 x 10(-8) M/liter at the time of CF administration. At 48 hours, plasma MTX levels continued to exceed 10(-8) M/liter--the break point for the appearance of clinical toxicity due to MTX. In six of sixteen, or 38%, an initial rise in hCG levels was observed. Five of the seventeen patients, or 29%, and the one patient with PSTT developed MTX resistance. The administered dose (approximately 30 mg/M2) and plasma pharmacokinetics did not differ significantly between the tumors that responded and became resistant to MTX. The authors conclude that MTX resistance in GTT occurs as a result of impaired cell membrane uptake, gene amplification of dihydrofolate reductase, or both.

Chorionic Gonadotropin↗
PubMed1991

Ablation of human choriocarcinoma xenografts in nude mice by antibody-directed enzyme prodrug therapy (ADEPT) with three novel compounds.

Three novel prodrugs have been designed for use as anticancer agents. Each is a bifunctional alkylating agent which has been protected to form a relatively inactive prodrug. They are designed to be activated to their corresponding alkylating agents at a tumour site by prior administration of an antitumour antibody conjugated to the bacterial enzyme carboxypeptidase G2 (CPG2) in a two-phase system called antibody-directed enzyme prodrug therapy (ADEPT). The Km and Vmax values for three different antibody-CPG2 conjugates were determined in relation to each prodrug. The Km values ranged from 4.5-12 mumol/l and the Vmax from 0.5-1.6 mumol/U/min. Athymic Nu/Nu mice with palpable transplanted human choriocarcinoma xenografts, which are resistant to conventional chemotherapy, were treated with anti-human chorionic gonadotropin antibodies conjugated to CPG2. This was followed by each of the three novel prodrugs. Significant increase in survival was obtained in three of the regimens tested using only one course of treatment. This demonstrates the potential of a tumour-localised bacterial enzyme to activate protected alkylating agents in order to eradicate an established human xenograft.

Alkylating Agents↗
PubMed1991

Weekly etoposide, methotrexate and actinomycin D, alternating with cyclophosphamide plus vincristine (EMA/CO): a phase II study in advanced gastric carcinoma.

A total of 27 patients with measurable/evaluable metastatic or locally advanced gastric carcinoma were given combination chemotherapy comprising etoposide, methotrexate, actinomycin D, cyclophosphamide and vincristine (EMA/CO). Ten achieved partial remission, giving a response rate of 37% (95% CI; 21.7%-66.3%), 12 attained stable disease, whereas five had disease progression despite treatment. Drug toxicity was moderate to severe. Five of those who achieved partial remission underwent an attempt to resect residual disease which was successful in only three patients.

Adenocarcinoma↗
PubMed1991

Optimum management of pineal germ cell tumours.

Non-seminomatous pineal region germ cell tumours have a poor prognosis when treated with radiation alone but little is known of the results of treatment with modern chemotherapy. Between 1983 and 1990 five pineal region germ cell tumours presented to the Charing Cross Hospital, London. All five patients received the EpPlt/OMB chemotherapy schedule with escalated dose systemic methotrexate and intra-CSF methotrexate. Two patients had had prior radiotherapy. Four patients (80%) remain well and disease-free 6 months--5 years after completing therapy. Chemotherapy is an effective modality for the treatment of pineal germ cell tumours and should be used when non-seminomatous elements are present or when the placement of ventriculo-peritoneal shunt in the presence of malignant cells in the CSF presents a risk of dissemination.

Adolescent↗
PubMed1991

Results with the EMA/CO (etoposide, methotrexate, actinomycin D, cyclophosphamide, vincristine) regimen in high risk gestational trophoblastic tumours, 1979 to 1989.

OBJECTIVE: To assess the efficacy, toxicity and survival in patients with high risk GTT treated with the EMA/CO regimen (etoposide, methotrexate, actinomycin D, cyclophosphamide, vincristine/oncovine). DESIGN: Open non-randomized study of 148 consecutive patients referred to the Charing Cross Hospital between 1979 and 1989. SETTING: Trophoblastic disease centre in a London teaching hospital. SUBJECTS: 148 consecutive patients with high risk GTT were treated with the EMA/CO regimen. 76 patients had received no prior chemotherapy and 72 had received prior chemotherapy. MAIN OUTCOME MEASURES: Survival, causes of treatment failure and toxicity were analysed. RESULTS: Of 76 patients who had received no prior chemotherapy, 62 (82%) are in remission; an overall survival of 85% for the 148 patients. Ten of the 76 patients without prior chemotherapy died from extensive disease within 3 weeks of starting chemotherapy. The complete and partial response rates to EMA/CO chemotherapy were 80% and 18% respectively. The addition of cisplatin salvaged 9 of 11 (82%) who developed drug resistance and did not require surgery. Salvage surgery alone resulted in 7 of 8 (87%) having complete remissions. Relapse after EMA/CO chemotherapy is uncommon (5.4%) but survival is still relatively good with further chemotherapy and/or surgery with 6 (75%) of 8 patients obtaining a further sustained remission. Complications from EMA/CO chemotherapy are acceptable with myelosuppression being dose-limiting. Late sequelae are uncommon: menstruation usually returns with a few months, and no fetal abnormalities have been recorded in subsequent pregnancies. One patient developed what we presume to be a therapy-induced acute myeloid leukaemia. CONCLUSION: At present EMA/CO chemotherapy is our treatment of choice for patients with high risk GTT. Its toxicity is predictable and reversible. In patients developing drug resistance, salvage surgery is important. Future developments may include further dose intensification with the addition of haemopoietic growth factors, earlier diagnosis and the separation of gestational from non-gestational trophoblastic tumours.

Adult↗
PubMed1991

Selective uptake of toxic nucleoside (125IUdR) by resistant cancer.

We report uptake of a thymidine analogue 125-Iodine-5-iodo-2'-deoxyuridine (125IUdR) by nude mice bearing human xenografts of choriocarcinoma or colonic cancer. When 125IUdR was given alone, uptake by intestinal tissues was 5-10 times greater than by the tumours as measured by tissue gamma counting. This ratio was reversed when hydroxyurea or cytosine arabinoside were used as inhibitors of ribonucleotide reductase and were given in combination with 5-fluorouracil or methotrexate to inhibit thymidine synthesis shortly before injecting 125IUdR. Counting the radioactivity in tissues removed 24 hours after 125IUdR gave tumour to highest normal tissue ratios of up to 15:1, but the corresponding nuclear grain counts, which is probably a more reliable indicator of selective uptake into DNA, were in excess of 100:1. The addition of unlabelled IUdR to the regimen only reduced the uptake of 125IUdR when given in relatively large amounts. For this approach to be exploited it is concluded that the tumour must be resistant at the cell level to the inhibitor of DNA synthesis either de novo or as a result of prior exposure to it. This inhibitor can then be used to block uptake of the potentially toxic nucleoside analogue by normal renewal tissues while it is taken up by the resistant cancer cells. By inhibiting synthesis of the corresponding normal nucleosides with inhibitors to which the cancer cells are not resistant, incorporation of the toxic analogues into tumour DNA was enhanced. Although 125IUdR is a convenient agent for exploring this approach and is highly cytotoxic when incorporated in DNA, the clinical potential of reverse role chemotherapy probably lies with the development of toxic non-radioactive nucleoside analogues.

Adenocarcinoma↗
PubMed1991

Tissue dose estimates following the selective uptake of 125IUdR and other radiolabelled thymidine precursors in resistant tumours.

For the purposes of evaluation of the therapeutic potential of the radiohalogenated thymidine analogue 125IUdR, estimation of the radiation dose to the tumour cells and normal tissues is important. To determine the dose to any tissue from the radionuclide 125I is not simple, since the major emissions are very short-range Auger electrons. The cytotoxicity of 125I is strongly dependent on the position of the decay relative to the DNA, the principal target for cell sterilization. Estimates of the cytotoxicity of 125I based on the traditional MIRD recommended formulation (ICRU Report 32, 1979) may produce gross underestimates if it is incorporated into the DNA via the thymidine precursor 125IUdR. In this work, tissue count and autoradiography (ARG) data from studies by Bagshawe et al were used to estimate tissue doses following the administration of 125IUdR to LS174/T (a colorectal carcinoma) and CC3 (a choriocarcinoma) tumour-bearing animals, after a hydroxyurea block of the normal tissue turnover. The tumour cell toxicity is estimated from ARG data on the degree of 125I incorporation into the cell nucleus. Major drawbacks with 125I for this type of therapy are the long 60-day half-life, leading to radiological and waste disposal problems and the extreme short range of the radiotoxic effects. Possible alternative radiohalogens, 13I, 77Br, 131I and 211At, are suggested in place of 125I in the thymidine analog iododeoxyuridine. Dose calculations are performed and cytotoxicities estimated on the assumption that their biological retention characteristics are the same as for 125IUdR.

Adenocarcinoma↗
PubMed1991

Comparison of half-lives and cytotoxicity of N-chloroethyl-4-amino and N-mesyloxyethyl-benzoyl compounds, products of prodrugs in antibody-directed enzyme prodrug therapy (ADEPT).

The synthesis of two novel drugs, 4-[bis[2-(mesyloxy)ethyl]amino]benzoic acid (7) and 4-[(2-chloroethyl)[2-(mesyloxy)ethyl]amino]benzoic acid (8) is described here. They are the active drugs of two prodrugs (9 and 10) designed for use as anti-cancer agents. The prodrugs (9, 10 and 11) were made as a series of compounds which are bifunctional alkylating agents in which the activating effect of the ionized carboxyl function is masked through an amide bond to a glutamic acid residue. These relatively inactive prodrugs were designed to be activated to their corresponding alkylating agent active drugs (7, 8 and 12 respectively) at a tumour site by prior administration of a monoclonal antibody conjugated to a bacterial enzyme. This system is called antibody-directed enzyme prodrug therapy (ADEPT). The chemical half-lives of the prodrugs and their active drugs were measured in order to determine their relative reactivities. The half-lives ranged from 21 to 324 min for the active drugs and from 42 to 1158 min for the prodrugs. The viability of two different tumour cell lines was monitored with each active drug and prodrug. The IC50 values varied from 65 to 625 microM for the active drugs: no IC50 values could be obtained for the prodrugs, using a rapid incubation procedure. Each in vitro technique demonstrated the ability of the glutamic acid moiety to deactivate the drugs, forming effective prodrugs.

Antibodies, Monoclonal↗
PubMed1990

Gestational trophoblastic tumours following initial diagnosis of partial hydatidiform mole.

11 patients registered with an initial diagnosis of partial hydatidiform mole (PHM) subsequently required chemotherapy for a gestational trophoblastic tumour. In a retrospective review by histopathological examination and measurement of DNA ploidy, the diagnosis was confirmed as PHM in 5 cases and revised to complete hydatidiform mole in 4; in 2 cases there was no evidence of a molar pregnancy. 4 of the patients with PHM had no other known pregnancy before the gestational trophoblastic tumour and in 2 of these patients the tumour was diagnosed histologically as choriocarcinoma. Not all patients in whom PHM was diagnosed at referring hospitals proved to have the condition. Although the risk of a patient with PHM requiring chemotherapy for gestational trophoblastic tumour is of the order of 1 in 200, compared with 1 in 12 after a complete mole, there is no justification for excluding a patient from follow-up after the evacuation of a PHM.

Adult↗
PubMed1990

Serial measurements of Ca antigen in sera from patients with advanced malignant breast disease.

Ca antigen levels in serum samples from three groups of patients were assayed. From a survey of 173 patients with various malignancies, elevated levels were found most consistently in patients with metastatic breast cancer. Spearman rank correlation values of Ca and CEA values on individual serum samples, 0.3009, (n = 194), or individual and serial samples, 0.2406, (n = 264) from a total 194 patients with metastatic breast cancer showed that correlation between Ca and CEA values was poor. For a group of 20 patients within the 194, from whom fortnightly serial samples were available, serum levels for 10/20, measured retrospectively, corroborated clinical observations on the course of their disease, although only 4/20 showed marked elevations during active disease. No correlations between expression of the tumour marker and histological type of the primary tumour, age of the patient, site of recurrence nor aberrant elevation in response to cytotoxic drug could be found to explain the non-correspondence of marker behaviour and disease status in the remaining 10 patients. The indications from this small study are that serial Ca antigen serum measurement could be misleading in 50% of patients with metastatic breast cancer, and that the assay is unsuitable for follow-up of patients with breast cancer.

Adult↗
PubMed1990

A phase I/II study of the 5-HT3 antagonist GR38032F in the anti-emetic prophylaxis of patients receiving high-dose cisplatin chemotherapy.

A total of 24 patients who were receiving combination chemotherapy (POMB) including cisplatin at a dose of 100-120 mg/m2 were treated with the 5HT3 antagonist GR38032F (GR) as an anti-emetic prophylaxis. GR was given as a 15-min loading infusion followed by a 24-h infusion at three escalating dose levels of 1, 2 and 4 mg/h. In the first 24 h after commencing treatment, six patients had complete control of nausea and vomiting (CR), two had 1-2 emetic episodes (MR) and five had 3-5 emetic episodes (mR). The major response rate (CR + MR) was thus 35%. Eight responding patients (CR or MR) went on to receive oral GR at 8 or 12 mg t.i.d. for 5 days. In this group there was one CR, one MR, two mRs and four failures (F). There was no evidence of an improved therapeutic effect with increasing dose in either the infusion or the oral section of the study, although numbers were limited in the latter part of the trial. Toxicity was mild, with low-grade headache affecting 25% of patients being the most frequent side effect. Pharmacokinetic data was obtained in six patients at each dose level. There was a progressive rise in clearance with increasing dose, indicating that the kinetics are non-linear. However, there was no evidence of an association between high plasma levels and therapeutic efficacy. GR38032F is well tolerated and has promising single-agent activity in preventing vomiting induced by high-dose cisplatin.

Adult↗
PubMed1990

Accurate quantification of 131I distribution by gamma camera imaging.

The development of targeted therapy requires that the concentration of the therapeutic agent can be estimated in target and normal tissues. Single photon emission tomography (SPET), with and without scatter correction, and planar imaging using 131I have been compared to develop a method for investigation of targeted therapy. Compton scatter was investigated using line spread functions in air and water, these data were used to set a second peak, adjacent to the photopeak, for scatter correction. The system was calibrated with an eliptical phantom containing sources in background activity of various intensities. Scatter corrected reconstructions gave accurate estimates of activity in the sources regardless of background activity. For planar scanning and SPET without scatter correction there was an overestimate of activity in the source of 290% and 40% respectively. The validity of this method was confirmed in patients by comparing activity in the cardiac ventricles measured by SPET with scatter correction with that in a simultaneous blood sample. A coefficient of correlation of 0.955 was achieved with 25 data points. SPET with scatter correction was compared with planar imaging in measuring activity in the liver and spleen of patients receiving 75 mCi 131I-antibody to CEA intravenously. Planar imaging gave significantly higher values than SPET for the spleen (t = 5.4, P less than 0.001 by the paired t-test) but no significant difference for the liver. SPET with scatter correction forms a basis for an improved technique of quantifying the targeting efficiency.

Humans↗
PubMed1990

Respiratory failure due to choriocarcinoma: a study of 103 dyspneic patients.

Treatment of choriocarcinoma is mostly successful but there is still appreciable mortality from early respiratory failure. A series of 135 patients with choriocarcinoma presenting with dyspnea between 1960 and 1988 was studied to find prognostic factors for early respiratory death and to identify how mortality may be further reduced. Mortality with respect to early respiratory death (ERD) was 11% and was significantly associated with WHO prognostic score, chest X-ray appearance, central cyanosis, tachycardia, anemia, and clinical evidence of pulmonary hypertension. Indicators on chest X ray of high risk of ERD were the presence of more than 10 opacities, extensive opacification of lung fields, size of metastases, and hazy background obscuring the vascular pattern. Intensity of initial treatment was not correlated with this outcome. A set of criteria has been derived which will predict ERD with 100% sensitivity and 38% positive predictive value. These are opacification of lung fields on chest X ray of more than 50%, OR initial plasma hCG level greater than 10(5) when there is anemia and a history of chest pain. Patients presenting with choriocarcinoma and dyspnea who fulfill these criteria should be considered for extracorporeal perfusion techniques. As respiratory failure in this condition is characterized by hypoxemia and right-to-left shunting, extracorporeal perfusion should be effective. Ventilation should be avoided as no patient survived mechanical ventilation.

Adult↗
PubMed1990

Surgery and chemotherapy in the management of placental site tumor.

Since 1977 we have managed seven cases of placental site trophoblastic tumor. All patients were treated with hysterectomy. Three patients had preoperative chemotherapy without evidence of response. One of three patients presenting with no evidence of extrauterine spread and one of four presenting with extrauterine pelvic disease have died from metastatic disease on recurrence. One patient with pelvic disease and lung metastases at diagnosis has residual lung nodules, presumed necrotic, 47 months after completing chemotherapy. She received etoposide, methotrexate, and actinomycin D (EMA) alternating weekly with cyclophosphamide and vincristine (CO). Although surgical excision of placental site tumor remains the treatment of choice, EMA/CO chemotherapy may produce the occasional long-term survivor.

Adult↗
PubMed1990

Quantitative distribution of 131I-labelled monoclonal antibodies administered by the intra-ventricular route.

In a preliminary study in one patient [111In]DTPA was injected into the lateral ventricle and at the same time [99mT]DTPA into the lumbar sac. The 111In distributed freely throughout the CSF but the concentration of 99mTc in the ventricles remained consistently low. In the second phase of the study three patients with tumours confined to the neuraxis were treated with 20-50 mCi 131I-labelled monoclonal antibodies administered into the lateral ventricle via Ommaya reservoirs. Quantitative distribution of radio-labelled antibody was assessed at intervals up to 8 days post injection. In each case there was rapid distribution to all parts of the neuraxis with 38-68% of total CNS counts remaining in the head and 13-39% in each of the upper and lower half spine areas. The t1/2 for total CNS counts were 31.5, 19.8 and 15.5 h. There was no clear evidence of tumour localization and no neurological toxicity. These patients demonstrate that radiolabelled monoclonal antibodies can be given safely via Ommaya reservoirs and that in order to obtain optimal distribution throughout the CSF this should be the preferred method of administration. Further trials in patients with minimal disease are warranted.

Adult↗
PubMed1990

Novel prodrugs which are activated to cytotoxic alkylating agents by carboxypeptidase G2.

The synthesis of three novel prodrugs, 4-[bis[2-(mesyloxy)ethyl]amino]benzoyl-L-glutamic acid (7), 4-[(2-chloroethyl)[2-(mesyloxy)ethyl]amino]benzoyl-L-glutamic acid (8), and 4-[bis(2-chloroethyl)amino]benzoyl-L-glutamic acid (9), for use as anticancer agents, is described here. Each is a bifunctional alkylating agent in which the activating effect of the ionized carboxyl function is masked through an amide bond to the glutamic acid residue. These relatively inactive prodrugs are designed to be activated to their corresponding nitrogen alkylating agents (10, 11, and 12, respectively) at a tumor site by prior administration of a monoclonal antibody conjugated to the bacterial enzyme carboxypeptidase G2 (CPG2). The viability of two different tumor cell lines was monitored with each prodrug in the presence of CPG2. All three compounds showed substantial prodrug activity--with conversion to the corresponding active drug leading to greatly increased cytotoxicity.

Alkylating Agents↗