Morphine is the analgesic of choice for moderate to severe cancer pain; however, 10-30% of patients do not tolerate morphine. This study evaluated genetic variation in the m-opioid receptor, barrestin2, stat6 and uridine diphosphate-glucuronysltransferase 2B7 (UGT2B7) genes, in patients who responded to morphine vs those who were switched to alternative opioids. We prospectively recruited and genotyped 162 Caucasian patients (117 controls, 39 switchers). Switchers, were more likely to carry the common allele at 1182 G/A, 5864 G/A, 8622T/C and 11143 G/A in the barrestin2 gene (P ¼ 0.021, 0.043, 0.013, 0.043, respectively). Switchers had increased carriage of the T allele (À1714 C/T) and a significant difference in the allelic frequency at 9065 C/T (w 2 ¼ 3.86, P ¼ 0.049) in the stat6 gene. No differences were seen in genotype or allele frequencies of SNPs in the mopioid receptor gene or UGT2B7 gene. This study presents novel data suggesting that variation in genes involved in m-opioid receptor signalling influence clinical response to morphine.

There is no consensus as to the management of untreated poor prognosis or relapsed/refractory germ cell tumours. We have studied an intensive cisplatin-based regimen that incorporates high-dose methotrexate (HD MTX) and actinomycin-D and etoposide every 14 days (GAMEC). Sixty-two patients were enrolled in a phase 2 study including 27 who were untreated (IGCCCG, poor prognosis) and 35 with progression despite conventional platinum based chemotherapy. The pharmacokinetics of the drugs were correlated with standard outcome measures. Twenty of the untreated patients were progression free following GAMEC and appropriate surgery, as were 18 individuals in the pretreated group. None of the established prognostic factors for therapy for pretreated patients could identify a poor-prognosis group. Five out of nine late relapses to prior chemotherapy were progression free following GAMEC and appropriate surgery. All patients had at least one episode of febrile neutropenia and there were five (8%) treatment-related deaths. PK values were not predictive of efficacy or toxicity, although the dose intensity in the pretreated group of patients, especially of HD MTX, was significantly correlated with progression-free survival (PFS). GAMEC is a novel intensive regimen for this group of patients producing encouraging responses, although with significant toxicity. For those in whom it fails, further therapy is still possible with durable responses being seen.

Suramin is an antitrypanosomal agent with antineoplastic activity, but with serious systemic side effects. We administered Suramin intravesically to determine a concentration with low toxicity but with evidence of a pharmacodynamic effect, to recommend a dose level for phase II trials. This was an open-labelled, nonrandomised dose-escalation phase I study. In all, 12 patients with a history of recurrent superficial bladder cancer were grouped into four dose levels (10 -150 mg ml À1 in 60 ml saline). Six catheter instillations at weekly intervals were used. Cystoscopy and biopsy were performed before and 3 months after the start of treatment. Suramin was assayed using high-performance liquid chromatography, vascular endothelial growth factor (VEGF) using ELISA (enzyme-linked immunosorbent assay), and urinary protein profile using surface-enhanced laser desorption ionisation mass spectroscopy (SELDI). Minimal systemic absorption of Suramin was found at the highest dose of 150 mg ml À1 . Urinary VEGF was affected by Suramin at doses above 50 mg ml À1 , corresponding to the estimated threshold of saturation of Suramin binding to urine albumin. SELDI showed a specific disappearance of urinary protein peaks during treatment. Intravesical Suramin shows lack of toxicity and low systemic absorption. The results of this phase I trial support expanded clinical trials of efficacy at a dose of 100 mg ml À1 intravesically.

SN-38 is the active metabolite of CPT-11, a water-soluble derivative of the plant alkaloid camptothecin (CPT). Camptothecins exhibit a wide range of anti-neoplastic activity. They exert their cytotoxic effect through a single intracellular target, the nuclear enzyme topoisomerase I (topo I) (Hsiang et al, 1985;Hsiang and Liu, 1988), which relieves torsional strain introduced in the DNA duplex by active replication and transcription. The enzyme cleaves one of the strands of the duplex DNA, allowing the 5´-end of the cleaved strand to rotate around the internucleotide bond of the intact strand. Resealing of the cleaved strand after one or several strand passages completes enzyme action (Wang, 1985;Liu, 1989). CPT and its analogues slow the relegation step of the topo I catalytic cycle without affecting the DNA cleavage reaction. As a result, topo I-DNA adducts (cleavable complexes) are stabilized in the presence of CPT, resulting in single-strand DNA breaks.Although the frequency of cleavable complexes correlates well with cytotoxicity of CPTs, the single-strand breaks are readily reversible upon removal of the drug and are not lethal to the cell. This suggests the involvement of additional factors. A model that accommodates the experimental data involves the collision of the replication machinery with the cleavable complex (Hsiang et al, 1989), causing the replication fork to arrest and a potentially lethal double-stranded break to occur, ultimately leading to apoptotic cell death.This model explains the cytotoxicity of topo I-acting drugs towards cells in the S phase of the cell cycle. Therefore, although topo I is expressed throughout the cell cycle, it can be expected that topo I drugs will be phase-specific, and in clinical use schedule-dependent. Although camptothecin analogues are undergoing extensive investigation in clinical trials, relatively little information is available regarding the optimum schedule of these compounds. Therapeutic advantage with prolonged or repeated dosing schedules of topotecan and irinotecan in different mouse xenograft models has been described by several research groups (Kawato et al, 1991;Phillips et al, 1994;Houghton et al, 1995). The same results were obtained with topotecan in a soft-agar cloning system (Burris et al, 1992). In other mouse xenograft models CPT-11 appeared not to be markedly schedule-dependent in terms of toxicity, although the intermittent and prolonged schedules allowed moderately higher total dosages to be administered and were more active in this model (Bissery et al, 1996).In addition to cytotoxic effects, CPTs cause cell cycle arrest in G2/M at low to moderate concentrations, probably as a result of failure to activate cdc2 kinase, an enzyme involved in phosphorlation reactions required to induce mitosis, whereas at higher concentrations arrest can also be observed in early S (Del Bino Schedule-dependent cytotoxicity of SN-38 in p53 wild-type and mutant colon adenocarcinoma cell lines RH te Poele and SP JoelBarry Reed Oncology Laboratory, Department of...

Chronic myeloid leukaemia is typically characterised by the presence of dysregulated BCR -ABL tyrosine kinase activity, which is central to the oncogenic feature of being resistant to a wide range of cytotoxic agents. We have investigated whether the inhibition of this tyrosine kinase by the novel compound STI571 (formerly CGP57148B) would render K562, KU812 cell lines and chronic myeloid leukaemia-progenitor cells sensitive to induction of cell kill. Proliferation assays showed STI571 to be an effective cytotoxic agent in chronic myeloid leukaemia-derived cell lines (IC 50 on day 5 of 4.6 mg ml 71 and 3.4 mg ml 71 for K562 and KU812 respectively) and in leukaemic blast cells (per cent viability on day 3 at 4 mg ml 71 : 55.5+8.7 vs 96.4+3.7%). STI571 also appeared to specifically target bcr -abl expressing cells, as results from colony forming assays using the surviving cell fraction from STI571-treated peripheral CD34 + chronic myeloid leukaemia blast cells, indicated a reduction in the expansion of colonies of myeloid lineage, but no effect on normal colony formation. Our data also showed synergy between STI571 and other anti-leukaemic agents; as an example, there were significant increases in per cent cell kill in cell lines cultured with both STI571 and etoposide compared to the two alone (per cent cell kill on day 3: 73.7+11.3 vs 44.5+8.7 and 17.8+7.0% in cultures with STI571 and etoposide alone respectively; P50.001). This study confirms the central oncogenic role of BCR -ABL in the pathogenesis of chronic myeloid leukaemia, and highlights the role of targeting this tyrosine kinase as a useful tool in the clinical management of the disease.

SUMMARY. A specific antiserum for morphine-6-glucuronide (M6G) has been raised in a rabbit in response to immunization with a novel hapten: protein conjugate (N-aminobutylnormorphine-6-glucuronide-thyroglobulin). Cross-reactivity with morphine and structurally related compounds was found to be negligible as expected from the nature of this immunogen. Using this antiserum, a simple, rapid and robust radioimmunoassay (RIA) has been developed for determination of M6G in samples of human plasma. The assay has a sensitivity of 0·05 ng/mL using 100J.LL sample volumes and affords complete recovery of M6G over the range 2-200 ng/mL. The presence of morphine or morphine-3-glucuronide at concentrations up to 100 times the levels of M6G did not result in any measurable interference. Close agreement was obtained between M6G results obtained using the RIA and a specific high-performance liquid chromatography assay. This RIA offers an attractive alternative to existing methods for the determination of M6G in human plasma and will facilitate further metabolic and pharmacokinetic studies of morphine and M6G in the clinical setting. Additional key phrases: opiates; morphine metabolitesIt is now well recognized that morphine-6-glucuronide (M6G) is an important metabolite of morphine and makes a significant contribution to the analgesic activity usually attributed to the parent compound. Although the major metabolite of morphine, morphine-3-glucuronide (M3G), is pharmacologically inactive, it was demonstrated some twenty years ago that M6G is 20-45 times more analgesic, with a longer duration of action, than morphine itself after intracerebroventricular administration.' More recently, the analgesic activity of M6G has also been demonstrated in man? and significant quantities of this metabolite have been found following both acute and chronic administration of morphine. Indeed, the ratio of the area under the plasma concentration versus time curves for morphine, M3G and M6G after oral morphine administration is approximately 1; 10 : 50, respectively. 3,4 M6G has also been