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Biomedical subjects

N Thatcher

Publications and source records attributed to N Thatcher.

At least 109 records · Page 6Linked to original sources
PubMed1995

Chemotherapy with vincristine/ifosfamide/carboplatin/etoposide in small cell lung cancer.

Although chemotherapy is considered the cornerstone of treatment for small cell lung cancer (SCLC), the majority of SCLC patients relapse and die of their disease within 2 years of diagnosis. Until newer, more effective drugs are developed, both optimization of available chemotherapeutic regimens and the use of combined chemotherapy/radiotherapy will be required to improve the survival of SCLC patients. Combining ifosfamide, carboplatin, and etoposide, among the most active single agents against SCLC, into the ICE regimen was a logical move that has resulted in improved response and survival rates. In limited and extensive SCLC, respectively, ICE and ICE administered with vincristine (VICE) have achieved overall response rates of 79% to 94% and 77% to 100% and 2-year survival rates of 24% to 33% and 9% to 25%, respectively. Treatment-related toxicities, especially myelosuppression, have hindered efforts to accelerate the administration of ICE and VICE regimens and to incorporate them into combined-modality treatments. However, the use of hematologic support measures, including growth factors and peripheral blood progenitor cells, may pave the way for maximizing the effectiveness of these regimens.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Conducting clinical research in the new NHS: the model of cancer. United Kingdom Coordinating Committee on Cancer Research.

The United Kingdom Coordinating Committee on Cancer Research represents the major organizations funding cancer research in the United Kingdom. The deliberations of a working party convened by the committee to evaluate recently expressed concerns that the changes in the NHS threaten research, especially clinical trials to evaluate new treatments, are reported. A survey of contributors to trials coordinated by the committee showed that half are now experiencing difficulties in continuing to participate in clinical trials. The two major problems identified were lack of time and of staff, especially for NHS staff in non-teaching hospitals. Recent changes in junior doctors' hours and proposed reductions in the length of time for training will exacerbate this. It is possible to identify the direct and indirect excess costs of conducting research in the NHS, but currently the mechanism does not exist to designate funds specifically for this purpose. Consultation with the regional directors of research and development confirmed that the service increment for teaching and research is not the solution for this. Proposals are made to secure future clinical research in the NHS, including finance, indemnity, the licensing of new drugs, the greater use of nurse counsellors, and the value of cancer registries.

Clinical Trials as Topic↗
PubMed1994

Relationships between the formation of O6-methyldeoxyguanosine by 1-p-carboxyl-3,3-dimethylphenyltriazene in DNA and O6-alkylguanine-DNA alkyltransferase in human peripheral leukocytes.

There is increasing experimental evidence to indicate that O6-methyldeoxyguanosine (O6-MedG) formation in DNA is a critical cytotoxic event following exposure to certain antitumor alkylating agents and that the DNA repair protein O6-alkylguanine-DNA-alkyltransferase (ATase) can confer resistance to these agents. We recently demonstrated a wide interindividual variation in the depletion and subsequent regeneration of ATase in peripheral blood lymphocytes of patients treated with 24-h continuous infusion of 1-p-carboxyl-3,3-dimethylphenyltriazene (CB10-277) for metastatic melanoma. We have now measured the formation of O6-MedG in the DNA of peripheral leukocytes of nine patients receiving this treatment regimen. This lesion could be detected in DNA within 1 h and a progressive increase in adduct levels occurred during the CB10-277 infusion and for 24 h after completion. Considerable interindividual variation was observed in the peak O6-MedG levels, with values ranging from 3.0 to 23.8 mumol O6-MedG/mol deoxyguanosine (mean, 12.3 +/- 6.4 mumol O6-MedG/mol deoxyguanosine) following the first treatment cycle, possibly as a consequence of differences in the capacity of patients to metabolize CB10-277 to a methylating agent. There was, nevertheless, a clear temporal relationship between the progressive formation of leukocyte O6-MedG and lymphocyte ATase depletion. Repeated-measures regression showed that this was statistically significant (P < 0.001) during the CB10-277 infusion. A significant inverse correlation was also seen between pretreatment lymphocyte ATase activity and peak O6-MedG levels in leukocyte DNA (r = -0.73) and the area under the leukocyte O6-MedG concentration-time curve (r = -0.76). Metabolism of CB10-277 to a methylating agent could be one factor that combines with DNA repair capacity to determine clinical response, because the two responses observed in this series occurred in the two patients with the highest leukocyte O6-MedG levels and also the lowest pretreatment ATase activity. Hematological toxicity developed in the same two patients.

Adult↗
PubMed1994

Metastatic carcinoma of uncertain primary site: a retrospective review of 57 patients treated with vincristine, doxorubicin, cyclophosphamide (VAC) or VAC alternating with cisplatin and etoposide (VAC/PE).

BACKGROUND: Metastatic carcinoma of uncertain primary site (CUPS) is a common problem and has a poor prognosis. The intention of this study was to determine whether the addition of cisplatin and etoposide (PE) to vincristine, doxorubicin and cyclophosphamide (VAC) chemotherapy improves outcome. METHODS: Fifty-seven consecutive patients with an initial diagnosis of CUPS were studied. The first 40 patients had received six or 10 cycles of VAC and 17 patients VAC alternating with PE for six cycles. Review of histology using immunohistochemical techniques where appropriate was performed in all cases. RESULTS: Histologic review resulted in six tumors reclassified as non-Hodgkin's lymphoma (NHL), one as hepatocarcinoma, and one as adenocarcinoma. Six of the 11 responses occurred in patients with a review diagnosis of NHL. If the six cases of NHL and the case of hepatocarcinoma were excluded, there was no difference in survival between VAC and VAC/PE treated patients. Five patients with true CUPS who responded to VAC or VAC/PE had poorly differentiated histology, and this group (n = 24) also had a significantly longer survival. CONCLUSIONS: Some patients thought to have CUPS actually have NHL, and it is this group which responds well to chemotherapy. True CUPS patients respond to chemotherapy only if the tumor is poorly differentiated; survival is significantly longer for this group of patients. An advantage for VAC/PE over VAC chemotherapy was not identified.

Adenocarcinoma↗
PubMed1994

Treatment evaluation of combined modality therapy: 'what can we obtain today from phase II trials?'.

Demonstration of activity is the major goal of Phase II studies. Other end points-duration of response, survival (relapse free in complete responders), progression free interval, changes in performance status and quality of life also provide useful information. From these data a decision to continue or discard a particular therapy can be considered. Various handicaps including variability in response reporting, heterogeneity of patient populations, inadequate reporting of failure patterns, causes of death, performance status changes and quality of life hinder interpretation of Phase II data. Nevertheless, Phase II studies have defined prognostic groups, beneficial changes in performance status and have helped formulate novel management approaches. Targeting particular prognostic groups, investigating dose-intensive regimens with haemopoietic growth-factor support and novel combined-modality approaches have all been generated through Phase II investigations.

Actuarial Analysis↗
PubMed1994

Therapy for small cell lung cancer using carboplatin, ifosfamide, etoposide (without dose reduction), mid-cycle vincristine with thoracic and cranial irradiation.

The aim of this study was to assess the efficacy and toxicity of intensive chemotherapy, administered without dose reduction, with cranial and thoracic radiotherapy given when possible as a single fraction in small cell lung cancer. 87 patients were eligible on the basis of good performance status, normal or near normal biochemistry and clinical staging, 73 limited and 14 extensive stage, computed tomography scanning was not mandatory. Six cycles of carboplatin, ifosfamide and etoposide with vincristine on day 15 at 4 weekly intervals were planned. Dosages were not reduced in response to myelosuppression. Prophylactic cranial irradiation (PCI) as a single fraction after the first cycle and thoracic irradiation (when possible as a single fraction) following the third cycle were delivered. Seventy-two per cent of patients completed the protocol. Complete response rate was 55% and 26% of patients had a partial response. The median nadirs of neutropenia were 0.5 x 10(9)/l and thrombocytopenia 14 x 10(9)/l, with 6% probable treatment-related deaths. Performance status and dyspnoea improved markedly to normal or near normal levels following the second course. Brain metastases occurred in 13% of patients. The median survival was 16.2 months with a 2-year survival of 31% (95% confidence interval, 24-41%) for a minimum follow-up of 26 months. These results compare favourably with other combined modality studies, using multiple radiotherapy fractions with cisplatin-based combinations and dosage reduction for patients staged in more anatomical detail. The toxicity spectrum and efficacy data could lead to the use of this chemotherapy regimen with haematopoietic growth factors and, in the future, peripheral blood progenitor cell rescue.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Neurological and cognitive impairment in long-term survivors of small cell lung cancer.

Despite its effectiveness in reducing the rate of brain metastases, the role of prophylactic cranial irradiation (PCI) in the management of small cell lung cancer (SCLC) remains controversial because of concern about radiation-induced neurological morbidity. In order to evaluate morbidity and its impact on quality of life 64 patients surviving > or = 2 years in remission were recalled for assessment. 52 had received PCI. Most of the patients were well: 95% had performance status < or = 1 and nine out of 37 neurological examinations were abnormal. On neuropsychometric testing, only 19% of patients performed at the level expected for their age and intellectual ability on all four tests used. Fifty-four per cent of patients were impaired on two or more of the tests, suggesting a significant degree of measurable cognitive dysfunction. The number of patients who had not received PCI was insufficient for comparative analysis with the number who had, but among those treated with PCI, patients receiving 8 Gy in 1 fraction appeared less impaired than those receiving higher radiation doses in multiple fractions. The study showed that neuropsychometric testing is acceptable to patients, can be administered by non-psychologists in the clinic and is sensitive to otherwise undetected deficits of cognitive function in this patient population. Prospective evaluation of PCI should include neuropsychometric testing.

Adult↗
PubMed1994

Tropisetron compared with a metoclopramide-based regimen in the prevention of chemotherapy-induced nausea and vomiting.

This randomised, open, parallel group study compared the antiemetic efficacy and tolerability of tropisetron with metoclopramide plus lorazepam in 102 patients receiving a first course of non-cisplatin-containing chemotherapy. Control of acute vomiting by tropisetron was significantly superior to that of the metoclopramide regimen, with total control (no vomiting) in 45% of 51 patients in the tropisetron group compared with 22% of 51 patients in the metoclopramide group (P = 0.013); total and partial control (< 5 vomits) occurred in 67 and 47% of patients, respectively (P = 0.044). The incidences of acute nausea and of delayed nausea and emesis were similar in the two treatment groups. Both tropisetron and metoclopramide were well tolerated; no adverse effects were attributed to tropisetron administration with the exception of headache. One patient in the metoclopramide group reported confusion and tremor thought to be related to the antiemetic therapy. Tropisetron is an effective and well-tolerated agent in the prevention of chemotherapy-induced vomiting. The control of acute nausea was similar in the two treatment groups, but tropisetron was superior to a metoclopramide-based regimen in the control of acute vomiting.

Acute Disease↗
PubMed1994

Formation and loss of O6-methyldeoxyguanosine in human leucocyte DNA following sequential DTIC and fotemustine chemotherapy.

There is increasing evidence to indicate that O6-methyldeoxyguanosine (O6-MedG) formation in DNA is a critical cytotoxic event following exposure to certain anti-tumour alkylating agents and that the DNA repair protein O6-alkylguanine-DNA alkyltransferase (ATase) can confer resistance to these agents. We recently demonstrated a wide inter-individual variation in the depletion and subsequent regeneration of ATase in human peripheral blood lymphocytes following sequential DTIC (400 mg m-2) and fotemustine (100 mg m-2) treatment, with the nadir ATase activity occurring approximately 4 h after DTIC administration. We have now measured the formation and loss of O6-methyldeoxyguanosine (O6-MedG) in the DNA of peripheral leucocytes of eight patients receiving this treatment regimen. O6-MedG could be detected within 1 h and maximal levels occurred approximately 3-5 h after DTIC administration. Following the first treatment cycle, considerable inter-individual variation was observed in the peak O6-MedG levels, with values ranging from 0.71 to 14.3 mumol of O6-MedG per mol of dG (6.41 +/- 5.53, mean +/- s.d.). Inter- and intra-individual variation in the extent of O6-MedG formation was also seen in patients receiving additional treatment cycles. This may be a consequence of inter-patient differences in the capacity for metabolism of DTIC to release a methylating intermediate and could be one of the determinants of clinical response. Both the pretreatment ATase levels and the extent of ATase depletion were inversely correlated with the amount of O6-MedG formed in leucocyte DNA when expressed either as peak levels (r = -0.59 and -0.75 respectively) or as the area under the concentration-time curve (r = -0.72 and -0.73 respectively). One complete and one partial clinical response were seen, and these occurred in the two patients with the highest O6-MedG levels in the peripheral leucocyte DNA, although the true significance of this observation has yet to be established.

Adult↗
PubMed1994

Inactivation of O6-alkylguanine-DNA alkyltransferase in human peripheral blood mononuclear cells by temozolomide.

O6-alkylguanine-DNA-alkyltransferase (ATase) activity was measured in extracts of peripheral blood mononuclear cells (PMCs) taken from eight patients at various times during 5 days of oral treatment with temozolomide (150 mg m-2, days 1-5). Pretreatment ATase levels ranged from approximately 70 to 600 fmol per mg of protein. Depletion of PMC ATase was seen within 4 h of the first dose of temozolomide and had a median nadir of 52.9% and values ranging from 44.4% to 71.0% of pretreatment levels. There was a correlation between the extent of ATase depletion (pretreatment minus nadir level) and the pretreatment ATase level (r = 0.97). A progressive depletion of ATase was observed during the 5 days of continuous temozolomide therapy with median ATase activities of 66.3%, 52.5%, 39.5%, 30.5% and 28.9% of the pretreatment values at days 2, 3, 4, 5 and 6 respectively. This suggests that the schedule-dependent anti-tumour activity of temozolomide seen in experimental models and clinics may be related to a cumulative depletion of ATase.

Administration, Oral↗
PubMed1994

Excitotoxic amino acids cause appearance of magnetic resonance spectroscopy-observable zinc in superfused cortical slices.

(1) The effects of glutamate and NMDA on the free intracellular calcium concentration ([Ca2+]i) have been followed in superfused cortical slices using the 19F-magnetic resonance indicator 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid (5FBAPTA). (2) Glutamate (0.5 or 1 mM) caused a 75-100% increase in [Ca2+]i, and a new resonance was attributed to zinc-5FBAPTA, which was confirmed from its disappearance in the presence of a high-affinity chelator of heavy metals, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine. The appearance of zinc occurred with or just after the rise in [Ca2+]i and was independent of Mg2+. (3) NMDA, N-methyl-DL-aspartate, or N-methyl-L-aspartate (10-200 microM) caused a slower increase in [Ca2+]i, and zinc was observed in some but not all experiments. When present, zinc appeared later than the increase in [Ca2+]i. These changes were also independent of Mg2+. (4) Decreases in both phosphocreatine and ATP were observed in all of these studies. (5) The results are discussed in terms of the proposed role of zinc as a modulator of excitotoxicity. Observations of zinc after exposure to glutamate or more slowly to NMDA, but not after depolarisation or deprivation of glucose and O2 (where increases also occur in [Ca2+]i), suggest that the cellular damage caused by the latter insults (depolarisation and fuel deprivation as in ischaemia) involves mechanisms not solely attributable to release of excitotoxins.

Animals↗
PubMed1994

ACTH precursors characterize the ectopic ACTH syndrome.

OBJECTIVE: ACTH is secreted by the pituitary following processing of larger molecular weight precursors, proopiomelanocortin and pro-ACTH. Ectopic ACTH syndrome refers to the secretion of ACTH by non-pituitary tumours, but the predominant circulating form of proopiomelanocortin-related peptides remains unclear. PATIENTS: Fifteen patients with ectopic ACTH syndrome were compared to 20 patients with pituitary-dependent Cushing's syndrome, 22 patients with small cell lung carcinoma but no evidence of Cushing's syndrome, and 25 controls. DESIGN AND MEASUREMENTS: Measurement of plasma ACTH and ACTH precursors using specific monoclonal-based immunoradiometric assays at 0900 h and, in five patients with ectopic ACTH syndrome, at 15-minute intervals for 6-24 hours. RESULTS: ACTH precursors were grossly elevated in patients with ectopic ACTH syndrome (median 2194, range 139-18000 pmol/l) compared to patients with Cushing's disease (median 33, 8-73 pmol/l, P < 0.001), patients with small cell lung carcinomas (38, 8-117 pmol/l, P < 0.001) and controls (26, 10-39 pmol/l, P < 0.001). ACTH levels were also elevated in ectopic ACTH syndrome (0900 h median 34, 11-152 pmol/l) compared to patients with Cushing's disease (0900 h median 8, 3-19 pmol/l), but not to the same degree as ACTH precursors. In contrast with Cushing's disease, ACTH was secreted in a non-pulsatile fashion. ACTH precursors but not ACTH itself correlated with plasma cortisol in patients with ectopic ACTH syndrome (r = 0.65, P < 0.05). Chromatographic analysis of plasma from a patient with ectopic ACTH syndrome confirmed ACTH precursors and not ACTH to be the predominant circulating form. With the cross-reactivity of proopiomelanocortin and pro-ACTH in the ACTH IRMA of < 1 and < 10% respectively, ACTH precursors could represent all the ACTH immunoreactivity in patients with ectopic ACTH syndrome. CONCLUSIONS: Ectopic 'ACTH' is characterized by aberrant processing of proopiomelanocortin and should be more accurately referred to as 'ectopic ACTH precursor syndrome'.

ACTH Syndrome, Ectopic↗
PubMed1994

Single-agent activity of weekly gemcitabine in advanced non-small-cell lung cancer: a phase II study.

PURPOSE: To evaluate the efficacy and safety of gemcitabine, a pyrimidine antimetabolite with activity against solid tumours. PATIENTS AND METHODS: Eighty-two patients with unresectable stage IIIa to IV non-small-cell lung cancer (NSCLC) were entered. The first 54 patients received gemcitabine 800 mg/m2, and subsequent patients 1,000 mg/m2, as a 30-minute intravenous infusion on days 0, 7, and 14. Courses of therapy were repeated every 28 days. Twenty percent dosage escalation was permitted after course no.1 if World Health Organization (WHO) toxicity was < or = 1. RESULTS: Sixteen (20%; 95% confidence interval [CI], 12% to 31%) of 79 patients assessable for response had independently validated partial responses, with a median duration of 7 months. The overall median survival duration was 7 months. Gemcitabine improved disease-related symptoms (70% patients) and increased WHO performance status (44%). Toxicity was generally mild and reversible. Patients experienced little WHO grade 3 and 4 toxicity, with anemia in four (5%), thrombocytopenia in one (1%), leukopenia in six (7%), and neutropenia in 18 (22%). Infection occurred in nine patients (12%) during the study (four were neutropenic), but there were no episodes of WHO grade 3 or 4 infection. WHO grade 3 and 4 biochemical toxicity occurred with transient elevations of transaminases in 10 patients (12%). Two patients had transient WHO grade 3 elevation of serum creatinine levels, and two developed acute renal failure 4 and 6 weeks after the last dose of gemcitabine. There was no WHO grade 4 symptomatic toxicity. WHO grade 3 vomiting occurred in 31 patients (38%) and grade 3 alopecia in one (1%). Flu-like symptoms were associated with gemcitabine administration in 36 patients (44%). Twenty-six patients (32%) experienced fever (1% WHO grade 3), 33 (40%) ankle edema not associated with cardiac failure, 31 (38%) lethargy, and 11 (13%) dyspnea. CONCLUSION: Gemcitabine is an active new agent in the treatment of NSCLC. This schedule was associated with little alopecia or myelosuppression. Gemcitabine warrants further investigation in other malignancies and in combination with other agents.

Adult↗
PubMed1994

Intensive combined-modality therapy in small cell lung cancer.

Combination ifosfamide/carboplatin/etoposide (ICE) chemotherapy and ICE plus mid-cycle vincristine (VICE) are reviewed. Thoracic radiotherapy and prophylactic cranial irradiation given as single fractions in the majority of patients have been intercalated with VICE in the later studies. The patient populations have not been intensively staged with computed tomography, etc, but do have reasonable Karnofsky performance status ratings and biochemical screens. A policy of no dose reduction over six courses of VICE chemotherapy has been followed in three consecutive studies of 166 patients. The minimum length of follow-up is 26 months and the 2-year survival rate is > or = 30%. Hematopoietic growth factor support in an attempt to overcome the considerable myelosuppression with VICE therapy is currently being evaluated.

Antineoplastic Combined Chemotherapy Protocols↗