The epidermal growth factor receptor-targeted monoclonal antibody cetuximab (Erbitux) was recently introduced for the treatment of metastatic colorectal cancer. Treatment response is dependent on Kirsten-Ras (K-Ras) mutation status, in which the majority of patients with tumour-specific K-Ras mutations fail to respond to treatment. Mutations in the oncogenes B-Raf and PIK3CA (phosphoinositide-3-kinase) may also influence cetuximab response, highlighting the need for a sensitive, accurate and quantitative assessment of tumour mutation burden.
Mutations in K-Ras, B-Raf and PIK3CA were identified by both dideoxy and quantitative pyrosequencing-based methods in a cohort of unselected colorectal tumours (n=102), and pyrosequencing-based mutation calls correlated with various clinico-pathological parameters.
The use of quantitative pyrosequencing-based methods allowed us to report a 13.7% increase in mutation burden, and to identify low-frequency (<30% mutation burden) mutations not routinely detected by dideoxy sequencing. K-Ras and B-Raf mutations were mutually exclusive and independently associated with a more advanced tumour phenotype.
Pyrosequencing-based methods facilitate the identification of low-frequency tumour mutations and allow more accurate assessment of tumour mutation burden. Quantitative assessment of mutation burden may permit a more detailed evaluation of the role of specific tumour mutations in the pathogenesis and progression of colorectal cancer and may improve future patient selection for targeted drug therapies.
K-Ras; mutation; dideoxy sequencing; pyrosequencing; colorectal tumour; personalised medicine
Hodgkin's disease; HLA-DPB1; HVR; susceptibility; resistance; polymorphic amino acid
This study shows that combinations of bryostatin 1, a novel modulator of protein kinase C currently under clinical evaluation, with the anti-oestrogenic agent tamoxifen caused a large synergistic enhancement of growth inhibition in P388 cells in vitro. The growth-inhibitory effects of bryostatin 1 in the presence of non-inhibitory concentrations of tamoxifen were increased by approximately 200-fold, whereas growth inhibition by tamoxifen in the presence of non-inhibitory concentrations of bryostatin 1 were increased over 30-fold. These data have been confirmed by isobologram analysis. The precise mechanism underlying this effect is unknown, although preliminary data implicating protein kinase C is presented. The magnitude of this synergistic effect, together with evidence of clinical responses seen when these agents were given sequentially in ovarian cancer, merits further study.
The purpose of this systematic study was to provide an up to date and reliable quantitative summary of the relative benefits of various types of chemotherapy (non-platinum vs platinum, single-agent vs combination and carboplatin vs cisplatin) in the treatment of advanced ovarian cancer. Also, to investigate whether well-defined patient subgroups benefit more or less from cisplatin- or carboplatin-based therapy. Meta-analyses were based on updated individual patient data from all available randomized controlled trials (published and unpublished), including 37 trials, 5667 patients and 4664 deaths. The results suggest that platinum-based chemotherapy is better than non-platinum therapy, show a trend in favour of platinum combinations over single-agent platinum, and suggest that cisplatin and carboplatin are equally effective. There is no good evidence that cisplatin is more or less effective than carboplatin in any particular subgroup of patients.
The activity and toxicity of single-agent standard-dose doxorubicin were compared with that of two schedules of high-dose epirubicin. A total of 334 chemonaive patients with histologically confirmed advanced soft-tissue sarcomas received (A) doxorubicin 75 mg m(-2) on day 1 (112 patients), (B) epirubicin 150 mg m(-2) on day 1 (111 patients) or (C) epirubicin 50 mg m(-2) day(-1) on days 1, 2 and 3 (111 patients); all given as bolus injection at 3-week intervals. A median of four treatment cycles was given. Median age was 52 years (19-70 years) and performance score 1 (0-2). Of 314 evaluable patients, 45 (14%) had an objective tumour response (eight complete response, 35 partial response). There were no differences among the three groups. Median time to progression for groups A, B and C was 16, 14 and 12 weeks, and median survival 45, 47 and 45 weeks respectively. Neither progression-free (P = 0.93) nor overall survival (P = 0.89) differed among the three groups. After the first cycle of therapy, two patients died of infection and one owing to cardiovascular disease, all on epirubicin. Both dose schedules of epirubicin were more myelotoxic than doxorubicin. Cardiotoxicity (> or = grade 3) occurred in 1%, 0% and 2% respectively. Regardless of the schedule, high-dose epirubicin is not a preferred alternative to standard-dose doxorubicin in the treatment of patients with advanced soft-tissue sarcomas.
In order to evaluate the potential clinical and economic benefits of granulocyte colony-stimulating factor (G-CSF, filgrastim) following peripheral blood progenitor cells (PBPC) rescue after high-dose chemotherapy (HDCT), 23 consecutive patients aged less than 60 years with poor-prognosis, high-grade non-Hodgkin's lymphoma (NHL) were entered into a prospective randomized trial between May 1993 and September 1995. Patients were randomized to receive either PBPC alone (n = 12) or PBPC+G-CSF (n = 11) after HDCT with busulphan and cyclophosphamide. G-CSF (300 microg day[-1]) was given from day +5 until recovery of granulocyte count to greater than 1.0 x 10(9) l(-1) for 2 consecutive days. The mean time to achieve a granulocyte count > 0.5 x 10(9) l(-1) was significantly shorter in the G-CSF arm (9.7 vs 13.2 days; P<0.0001) as was the median duration of hospital stay (12 vs 15 days; P = 0.001). In addition the recovery periods (range 9-12 vs 11-17 days to achieve a count of 1.0 x 10(9) l[-1]) and hospital stays (range 11-14 vs 13-22 days) were significantly less variable in patients receiving G-CSF in whom the values clustered around the median. There were no statistically significant differences between the study arms in terms of days of fever, documented episodes of bacteraemia, antimicrobial drug usage and platelet/red cell transfusion requirements. Taking into account the costs of total occupied-bed days, drugs, growth factor usage and haematological support, the mean expenditure per inpatient stay was pound sterling 6500 (range pound sterling 5465-pound sterling 8101) in the G-CSF group compared with pound sterling 8316 (range pound sterling 5953-pound sterling 15,801) in the group not receiving G-CSF, with an observed mean saving of 1816 per patient (or 22% of the total cost) in the G-CSF group. This study suggests that after HDCT and PBPC rescue, the use of G-CSF leads to more rapid haematological recovery periods and is associated with a more predictable and shorter hospital stay. Furthermore, and despite the additional costs for G-CSF, these clinical benefits are not translated into increased health care expenditure.
OBJECTIVE: To examine the effectiveness of routine clinic review in detecting relapse after treatment for Hodgkin's disease. DESIGN: Review of hospital records. SETTING: Regional centre for cancer treatment and research. SUBJECTS: 210 patients with Hodgkin's disease recruited to a chemotherapy trial protocol between 1984 and the end of 1990 who had achieved a complete or partial remission after treatment. MAIN OUTCOME MEASURES: The number of clinic visits made by patients over the period of observation, the number of relapses occurring during that time, and the route by which relapse was detected. RESULTS: The 210 patients generated 2512 outpatient reviews, and 37 relapses were detected. Thirty relapses (81%) were diagnosed in patients who described symptoms, which in 15 cases had resulted in an earlier appointment being arranged. In only four cases (11%; 95% confidence interval 4% to 25%) was relapse detected as a result of routine physical examination on investigation of a patient who did not have symptoms. CONCLUSIONS: Relapse of Hodgkin's disease after treatment is usually detected as a result of the investigation of symptoms rather than by routine screening of asymptomatic patients. It is therefore proposed that the frequency of routine follow up visits should be reduced and greater emphasis placed on patient education. This should underline the importance of symptoms and encourage patients to arrange an earlier appointment if these develop.
The aim of this study was to determine whether a very high-risk group based on presenting characteristics could be identified in patients with advanced Hodgkin's disease who may benefit from high-dose chemotherapy (HDCT). Between 1975 and 1992, 453 previously untreated patients aged under 60 years who did not progress in the first 6 months after the start of standard chemotherapy had their hospital notes reviewed. The outcomes analysed were early disease progression (in the 6- to 18-month window following the start of chemotherapy) and disease progression in the whole of the follow-up period. A Cox regression analysis was used to investigate the combined effects of a number of presenting characteristics on these outcomes. Despite the presence of factors with significant effects on the relative rate of progression, the absolute effects in a group identified as having the poorest prognosis were not especially poor. No group could be defined with a freedom from progression rate of less than 70% over 6-18 months, and the worst prognostic group, which included only 53 patients, had an overall freedom from progression rate of 57% at 5 years. Four other reported prognostic indices were evaluated using our data set, but none of the indices was more successful in identifying a very high-risk group. It has not been possible to define a sufficiently high-risk group of patients with Hodgkin's disease based on presenting characteristics for whom HDCT could be advised as part of primary treatment. The search for more discriminating prognostic factors identifying vulnerable patients with a high risk of relapse must continue before a role can be found for HDCT following conventional chemotherapy in patients without disease progression.
We have shown that large numbers of haemopoietic progenitor cells are mobilised into the blood after filgrastim [granulocyte colony-stimulating factor (G-CSF)] alone and filgrastim following cyclophosphamide chemotherapy in previously untreated patients with ovarian cancer. These cells may be used to provide safe and effective haemopoietic rescue following dose-intensive chemotherapy. Using filgrastim alone (10 micrograms kg-1), the apheresis harvest contained a median CFU-GM count of 45 x 10(4) kg-1 and 2 x 10(6) kg-1 CD34+ cells. Treatment with filgrastim (5 micrograms kg-1) following cyclophosphamide (3 g m-2) resulted in a harvest containing 66 x 10(4) kg-1 CFU-GM and 2.4 x 10(6) kg-1 CD34+ cells. There was no statistically significant difference between these two mobilising regimens. We have also demonstrated that dose-intensive carboplatin and cyclophosphamide chemotherapy can be delivered safely to patients with ovarian cancer when supported by peripheral blood progenitor cells and filgrastim. Carboplatin (AUC 7.5) and cyclophosphamide (900 mg m-2) given at 3 weekly intervals with progenitor cell and growth factor support was well tolerated in terms of haematological and systemic side-effects. Double the dose intensity of chemotherapy was delivered compared with our standard dose regimen when the treatment was given at 3 weekly intervals. Median dose intensity could be further escalated to 2.33 compared with our standard regimen by decreasing the interval between treatment cycles to 2 weeks. However, at this dose intensity less than a third of patients received their planned treatment on time. All the delays were due to thrombocytopenia.
A study has been carried out to investigate the cellular distribution and levels of glutathione-S-transferase isoenzymes (GST), acidic (pi), basic (alpha) and neutral (mu), in ovarian tumour biopsies, and to measure GST activity in the same tumour specimens. Two methods of assessing isoenzyme levels (immunohistochemistry and Western blot) were compared. Well-known important clinicopathological features were correlated with response to treatment, overall survival and progression-free survival for each of 97 patients from whom biopsies had been obtained. The glutathione-S-transferase isoenzyme levels were also correlated with overall and progression-free survival, and with the important clinicopathological features. As expected, there was a significant correlation between FIGO stage, histological grade of tumour, amount of residual disease after staging laparotomy, response to chemotherapy, and both overall and progression-free survival. Glutathione-S-transferase isoenzyme levels (acidic, basic and neutral) measured by Western blot were not found to be significantly correlated with any of the clinicopathological parameters tested. Using the immunohistochemistry method of detection there was a correlation between the GST acidic isoenzyme level and the amount of residual disease remaining after initial debulking surgery (higher levels were detected in the group with no residual disease, P=0.034), and also between the GST acidic isoenzyme level and the type of chemotherapy regimen used. Higher levels of the acidic isoenzyme were present in tumour biopsies taken from the patient group who had received a combination regimen (cyclophosphamide, carboplatin, ifosfamide and doxorubicin). The neutral and basic GST isoenzyme levels were not significantly correlated with any of the clinicopathological parameters. None of the GST isoenzyme levels were significantly correlated with response to treatment, overall survival or progression-free survival (using either method of detection). Similarly, glutathione transferase activity showed no significant correlation with prognosis or survival.
A survey of all hospital pharmacies in the former North Western Regional Health Authority has revealed that hospital personnel continue to prepare cytotoxic drugs in suboptimal conditions, despite the widespread introduction of pharmacy cytotoxic reconstitution services. Other concerns include the lack of formal training for medical staff in the administration of these agents and the frequent absence of written procedures for dealing with extravasation and chemotherapy errors.
Bryostatin 1 is a macrocyclic lactone derived from the marine invertebrate Bugula neritina. In vitro, bryostatin 1 activates protein kinase C (PKC), induces the differentiation of a number of cancer cell lineages, exhibits anti-tumour activity and augments the response of haemopoietic cells to certain growth factors. In vivo, bryostatin 1 is also immunomodulatory, but the range of tumours which respond to bryostatin 1 in xenograft tumour models is mostly the same as the in vitro tumour types, suggesting a direct mode of action. Nineteen patients with advanced malignancy were entered into a phase I study in which bryostatin 1 was given as a 24 h intravenous infusion, weekly, for 8 weeks. Myalgia was the dose-limiting toxicity and the maximum tolerated dose was 25 micrograms m-2 per week. The myalgia was cumulative and dose related, and chiefly affected the thighs, calves and muscles of extraocular movement. The mechanism of the myalgia is unknown. CTC grade 1 phlebitis affected every patient for at least one cycle and was caused by the diluent, PET, which contains polyethylene glycol, ethanol and Tween 80. Most patients experienced a 1 g dl-1 decrease in haemoglobin within 1 h of commencing the infusion which was associated with a decrease in haematocrit. Radiolabelled red cell studies were performed in one patient to investigate the anaemia. The survival of radiolabelled red cells during the week following treatment was the same as that seen in the week before treatment. However, there was a temporary accumulation of radiolabelled red cells in the liver during the first hour of treatment, suggesting that pooling of erythrocytes in the liver might account for the decrease in haematocrit. Total or activated PKC concentrations were measured in the peripheral blood mononuclear cells (PBMCs) of three patients for the first 4 h of treatment and during the last hour of the infusion. This showed that PKC activity was significantly modulated during the infusion. Bryostatin 1 is immunomodulatory in vitro, and we have confirmed this activity in vivo. An investigation of the first three cycles of treatment in seven patients showed an increased IL-2-induced proliferative response in peripheral blood lymphocytes and enhanced lymphokine-activated killer (LAK) activity. A previously reported rise in serum levels of interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF 1) was not confirmed in our study; of nine patients in this study, including patients at all dose levels, none showed an increase in these cytokines.(ABSTRACT TRUNCATED AT 400 WORDS)
Temozolomide, an imidazotetrazine derivative, was given to 18 patients with low-grade non-Hodgkin's lymphoma (NHL) at a dose of 750 mg m-2 orally, divided over five consecutive days, escalated to 1000 mg m-2 over 5 days (i.e. 200 mg m-2 day-1) if no significant myelosuppression was noted at day 22 of the 28 day cycle. Fifty-six treatment cycles were given to 18 patients. The drug was well tolerated. Only one partial tumour response was documented. The patients were heavily pretreated but had chemoresponsive disease, as shown by a response rate of 69% among 13 patients who went on to receive alternative cytotoxic regimens. We conclude that temozolomide given in this schedule is inactive in previously treated low-grade NHL.
We report a family with the Li-Fraumeni syndrome (LFS) in whom we have been unable to detect a mutation in the coding sequence of the p53 gene. Analysis of linkage to three polymorphic markers within p53 enabled direct involvement of p53 to be excluded. This is the first example of a LFS family in whom exclusion of p53 has been possible. Four affected members of the family with sarcoma or premenopausal breast cancer showed increased expression of p53 protein in their normal tissues as detected by immunohistochemistry. It therefore appears that the LFS phenotype has been conferred by an aberrant gene, showing a dominant pattern of inheritance, which may be acting to compromise normal p53 function rather than by a mutation in p53 itself. In order to try to determine the chromosomal location of this putative gene, we have carried out studies of linkage to candidate loci. By these means we have excluded involvement of Rb1 and BRCA1 on chromosomes 13q and 17q respectively. The MDM2 oncogene on chromosome 12q was considered to be the prime candidate as MDM2 is amplified in sarcomas and the MDM2 product binds to p53. Furthermore, p53 mutation and amplification of MDM2 have been shown to be mutually exclusive events in tumour development. Linkage analysis to two polymorphic markers within MDM2 yielded a three-point LOD score of -5.4 at a recombination fraction theta equal to zero. Therefore MDM2 could be excluded. It is possible that the gene which is responsible for cancer susceptibility in this family, possibly via interaction with p53, will be important in the histogenesis of breast cancer in general. We are now carrying out further studies to locate and identify this gene.
Bryostatin 1 is a novel macrocyclic lactone activator of protein kinase C (PKC) which has clinical potential as an anti-cancer agent. The mechanism of action of this agent is unknown, but protein kinase C has been implicated. In order to investigate this possibility, we have developed P388 sublines resistant to bryostatin 1, by continuous challenge of the parent cell line with increasing incremental concentrations of the drug over 4 months. Cell lines were established at monthly intervals yielding four sublines: P388/BR/A, which were removed at 1 month; P388/BR/B, obtained after 2 months; P388/BR/C, obtained after 3 months; and P388/BR/D, which were established after 4 months. All four P388/BR sublines show an equal degree of resistance to the growth inhibitory effects of bryostatin 1, with a relative resistance ratio (RR) IC50 of approximately 4,000. The ability of the cytosol of cells to phosphorylate PKC-specific substrate is decreased by 41% for BR/A, 57% for BR/B 80% for BR/C and 94% for BR/D compared with the parental cell line, even when grown in the absence of bryostatin 1 for up to 4 weeks. Similar decreases are seen for cytosolic phorbol ester binding and whole-cell PKC isoenzyme expression. All four P388/BR sublines show high and equal levels of cross-resistance to the PKC activatory phorbol ester, phorbol 12-myristate 13-acetate (PMA). There is no loss of resistance to either bryostatin 1 or PMA up to 3 months after termination of exposure of the sublines to bryostatin 1. There was no significant degree of cross-resistance to daunorubicin in the bryosatin 1-resistant cell lines, P388/BR/A, B, C or D, when compared with the parent cell line, P388.
We have measured bone mineral density (BMD) in 29 men, mean age 35.0 (range 19.7-58.0) years, with testicular damage following MVPP or hybrid chemotherapy for Hodgkin's disease. Forearm cortical bone mineral content (BMC) and lumbar spine and femoral neck integral BMD were measured 3.4 (1.1-6.8) years after completion of chemotherapy, and results expressed as Z (standard deviation) scores. There was a significant reduction in forearm cortical BMC (median BMC 1.727 g cm-1, median Z-score -0.8, P < 0.0005), in lumbar spine integral BMD (median BMD 1.141 g cm-2, median Z-score -0.6, P < 0.0005) and in femoral neck integral BMD (median BMD 0.991 g cm-2, median Z-score -0.4, P < 0.05). There was no significant correlation between Z-score and time elapsed since completion of chemotherapy, and no significant difference in Z-score according to type of chemotherapeutic regimen or number of cycles of chemotherapy received. In conclusion, men who are in complete remission following treatment of Hodgkin's disease have reduced cortical and trabecular BMD. Possible causes include mild hypogonadism secondary to chemotherapy-induced impairment of Leydig cell function, a direct effect of chemotherapy on bone, an effect of high-dose glucocorticoid on bone or an effect of Hodgkin's disease per se.
CPF1 is an abundant basic-helix-loop-helix-ZIP protein that binds to the CDEI motif in Saccharomyces cerevisiae centromeres and in the promoters of numerous genes, including those encoding enzymes of the methionine biosynthetic pathway. Strains lacking CPF1 are methionine auxotrophs, and it has been proposed that CPF1 might positively influence transcription at the MET25 and MET16 genes by modulating promoter chromatin structure. We test this hypothesis and show that the regions surrounding the CDEI motifs in the MET25 and MET16 promoters are maintained in a nucleosome-free state and that this requires the entire CPF1 protein. However, the chromatin structure around the CDEI motifs does not change on derepression of transcription and does not correlate with the methionine phenotype of the cell. An intact CDEI motif but not CPF1 is required for transcriptional activation from a region of the MET25 upstream activation sequence. Our results suggest that CPF1 functions to modulate chromatin structure around the CDEI motif but that these changes at the MET25 and MET16 promoters do not explain how CPF1 functions to maintain methionine-independent growth. The presence of CPF1-dependent chromatin structures at these promoters leads to a weak repression of transcription.
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.
Approximately 30-50% of cases of ovarian adenocarcinoma harbour mutations in the p53 tumour-suppressor gene associated with elevated levels of the protein detected by immunohistochemical staining. To investigate any relation between the presence of mutant p53 and clinicopathological features of disease, we examined a series of 50 cases of epithelial ovarian adenocarcinoma for expression of p53 by immunohistological staining on fixed, paraffin-embedded tissue sections using the polyclonal antibody CM1, and by direct nucleotide sequencing of polymerase chain reaction-amplified DNA from selected cases. Of the 50 cases examined, 28 (56%) were p53 positive and there was no significant correlation between p53 status and differentiation stage, clinical (FIGO) stage, multidrug resistance (mdr-1 P-glycoprotein) expression or response to treatment. However, we observed a statistically significant difference between the high prevalence of p53-positive serous tumours (18 out of 23) and the lower prevalence of p53-positive cases in mucinous tumours (3 of 12) suggesting that factors related to disease aetiology, associated with these histological subtypes, may determine the prevalence of functional inactivation of the p53 tumour-suppressor gene in ovarian adenocarcinoma.
Semen analysis was performed in 14 men a median of 13.5 months after completion of VAPEC-B chemotherapy for Hodgkin's disease or non-Hodgkin's lymphoma. Semen from 12 patients contained motile spermatozoa, and in nine cases the count was > 20 million ml-1. One patient was azoospermic (VAPEC-B followed by pelvic radiotherapy) and another had a count of 21 million ml-1 but sperm were non-motile. These findings suggest that, in the majority of cases, VAPEC-B chemotherapy does not cause permanent damage to the male germinal epithelium. A more detailed study of gonadal function in males and females before and after treatment with VAPEC-B for Hodgkin's disease is currently in progress.
Bryostatin 1 is a novel antitumour agent derived from Bugula neritina of the marine phylum Ectoprocta. Nineteen patients with advanced solid tumours were entered into a phase I study to evaluate the toxicity and biological effects of bryostatin 1. Bryostatin 1 was given as a one hour intravenous infusion at the beginning of each 2 week treatment cycle. A maximum of three treatment cycles were given. Doses were escalated in steps from 5 to 65 micrograms m-2 in successive patient groups. The maximum tolerated dose was 50 micrograms m-2. Myalgia was the dose limiting toxicity and was of WHO grade 3 in all three patients treated at 65 micrograms m-2. Flu-like symptoms were common but were of maximum WHO grade 2. Hypotension, of maximum WHO grade 1, occurred in six patients treated at doses up to and including 20 micrograms m-2 and may not have been attributable to treatment with bryostatin 1. Cellulitis and thrombophlebitis occurred at the bryostatin 1 infusion site of patients treated at all dose levels up to 50 micrograms m-2, attributable to the 60% ethanol diluent in the bryostatin 1 infusion. Subsequent patients treated at 50 and 65 micrograms m-2 received treatment with an intravenous normal saline flush and they did not develop these complications. Significant decreases of the platelet count and total leucocyte, neutrophil and lymphocyte counts were seen in the first 24 h after treatment at the dose of 65 micrograms m-2. Immediate decreases in haemoglobin of up to 1.9g dl-1 were also noted in patients treated with 65 micrograms m-2, in the absence of clinical evidence of bleeding or haemodynamic compromise. No effect was observed on the incidence of haemopoietic progenitor cells in the marrow. Some patients' neutrophils demonstrated enhanced superoxide radical formation in response to in vitro stimulation with opsonised zymosan (a bacterial polysaccharide) but in the absence of this additional stimulus, no bryostatin 1 effect was observed. Lymphocyte natural killing activity was decreased 2 h after treatment with bryostatin 1, but the effect was not consistently seen 24 h or 7 days later. With the dose schedule examined no antitumour effects were observed. We recommend that bryostatin 1 is used at a dose of 35 to 50 micrograms m-2 two weekly in phase II studies in patients with malignancies including lymphoma, leukaemia, melanoma or hypernephroma, for which pre-clinical investigations suggest antitumour activity.
A study involving the measurement of glutathione S-transferase activities and isoenzyme distributions in human ovarian tumours has been carried out. These tumours have been obtained either at initial debulking surgery, prior to cytotoxic chemotherapy, or at second look laparotomy following chemotherapy. The response rates of these two groups to chemotherapy differ markedly, with patients who have relapsed following initial chemotherapy showing a reduction in response rates to subsequent chemotherapy. Analysis of these data show no statistically significant differences between the glutathione S-transferase activity or isoenzyme distribution in these two groups of patients. Significant differences were observed in the glutathione-S-transferase activities (GST) between tumours and normal ovaries. GST activities in pre-chemotherapy tumours (n = 33, P = 0.01) and post-chemotherapy tumours (n = 20, P = 0.001) where significantly higher than the GST activity in normal ovaries (n = 15). One feature was the expression of the basic isoenzyme which is expressed more in normal ovaries than in tumours. No differences in these parameters were observed in normal peritoneal tissue taken from patients before or after chemotherapy. These data do not support the hypothesis that changes in glutathione S-transferase enzyme activity or isoenzyme expression are major determinants of response to chemotherapy in ovarian tumours.
O6-alkylguanine-DNA-alkyltransferase (ATase) levels were measured in extracts of peripheral blood lymphocytes taken at various times during chemotherapy from 19 patients with various haematological malignancies. Seven patients with advanced Hodgkin's disease received preparative treatment consisting of cyclophosphamide (1.5 g m-2, daily) administered on days 1 to 4 and BCNU (600 mg m-2) on day 5 prior to autologous bone marrow rescue (ABMR) delivered on day 7. Treatment in the remaining 12 patients consisted of cyclophosphamide (1.8 g m-2, daily) given on days 1 and 2 followed at day 4 with total body irradiation (TBI) administered in six fractions over the subsequent 3 days to a total dose of 1200 cGy prior to bone marrow transplantation. In the Hodgkin's group, significant decreases in ATase activity were seen during the cyclophosphamide treatment, and the median ATase nadir was 32% (range 0% to 57%) of pretreatment levels following 4 days of cyclophosphamide. In one patient, no ATase activity was detectable following the 4th cyclophosphamide treatment. ATase activities decreased further after BCNU administration to a median of 19% (range 0% to 32%) of pretreatment levels. Extensive cyclophosphamide-induced reduction of lymphocyte ATase levels was also seen in the other group of 12 patients treated with cyclophosphamide/TBI: postcyclophosphamide median ATase nadir was 35% (range 12% to 78%) of the pretreatment levels. No ATase depletion was seen when cyclophosphamide (up to 10 mM) was incubated for 2 h with pure recombinant human ATase in vitro whereas ATase activity was reduced by 90% on preincubation with 100 microns acrolein or with greater than 1 mM phosphoramide mustard. This suggests that a cyclophosphamide-induced decrease in ATase levels in human peripheral lymphocytes in vivo may be due to depletion mediated by the production of intracellular acrolein. Since ATase appears to be a principal mechanism in cellular resistance to the cytotoxic effects of BCNU and related alkylating agents, these observations suggest that a cyclophosphamide-induced reduction in ATase activity may be an additional factor in the effectiveness of the combined sequential therapy.