Scheduling nab-paclitaxel combined with gemcitabine as first-line treatment for metastatic pancreatic adenocarcinoma.

BACKGROUND: Nab-paclitaxel plus gemcitabine (nabP+gemcitabine) offers modest survival gains for patients with metastatic pancreatic ductal adenocarcinoma (PDAC). Sequential scheduling of nabP+gemcitabine in a PDAC mouse model improved efficacy; this hypothesis was tested in a clinical trial. METHODS: Patients with previously untreated metastatic PDAC were randomised to receive nabP+gemcitabine administered either concomitantly on the same day, or sequentially, with gemcitabine administered 24 h after nabP. The primary outcome measure was progression-free survival (PFS). Secondary outcome measures were objective response rate (ORR), overall survival (OS), safety, quality of life (QoL) and predictive biomarkers. RESULTS: In total, 71 patients received sequential (SEQ) and 75 concomitant (CON) treatment. Six-month PFS was 46% with SEQ and 32% with CON scheduling. Median PFS (5.6 versus 4.0 months, hazard ratio [HR] 0.67, 95% confidence interval [95% CI] 0.47-0.95, p = 0.022) and ORR (52% versus 31%, p = 0.023) favoured the SEQ arm; median OS was 10.2 versus 8.2 months (HR 0.93, 95% CI 0.65-1.33, p = 0.70). CTCAE Grade ≥3 neutropaenia incidence doubled with SEQ therapy but was not detrimental to QoL. Strongly positive tumour epithelial cytidine deaminase (CDA) expression favoured benefit from SEQ therapy (PFS HR 0.31, 95% CI 0.13-0.70). CONCLUSIONS: SEQ delivery of nabP+gemcitabine improved PFS and ORR, with manageable toxicity, but did not significantly improve OS. CLINICAL TRIAL REGISTRATION: ISRCTN71070888; ClinialTrials.gov (NCT03529175).

Intrinsic Charge Dynamics in High-T_{c} AFeAs(O,F) Superconductors.

We report the first determination of the in-plane complex optical conductivity of 1111 high-T_{c} superconducting iron oxypnictide single crystals PrFeAs(O,F) and thin films SmFeAs(O,F) by means of conventional and microfocused infrared spectroscopy, ellipsometry, and time-domain THz transmission spectroscopy. A strong itinerant contribution is found to exhibit a dramatic difference in coherence between the crystal and the film. Using extensive temperature-dependent measurements of THz transmission, we identify a previously undetected 2.5-meV collective mode in the optical conductivity of SmFeAs(O,F), which is strongly suppressed at T_{c} and experiences an anomalous T-linear softening and narrowing below T^{*}≈110 K≫T_{c}. The suppression of the infrared absorption in the superconducting state reveals a large optical superconducting gap with a similar gap ratio 2Δ/k_{B}T_{c}≈7 in both materials, indicating strong pairing.

Phase II, randomized, biomarker identification trial (MARK) for erlotinib in patients with advanced pancreatic carcinoma.

BACKGROUND: A prospective, randomized phase II study, with mandatory tumor sampling at current disease stage, aimed to identify biomarkers predictive of improved progression-free survival (PFS) in patients with pancreatic cancer treated with erlotinib. PATIENTS AND METHODS: Patients with histologically/cytologically confirmed, unresectable, locally advanced/metastatic pancreatic cancer, who had failed on or were unsuitable for first-line chemotherapy, underwent a tumor biopsy and were then randomized to receive once-daily erlotinib 150 mg or placebo. The primary end point was identification of biomarkers predicting improved PFS with erlotinib. Secondary end points included PFS, overall survival, response and toxicity. RESULTS: At data cut-off, 207 patients were enrolled and analyzed. Prespecified biomarker analyses of EGFR protein expression, EGFR gene copy number/mutations/polymorphisms and KRAS mutations did not identify any subgroups with a detrimental effect or a strong benefit for PFS with erlotinib. In the primary analysis, the median PFS was 6.1 versus 5.9 weeks in the erlotinib and placebo arms, respectively [hazard ratio (HR) 0.83; 95% confidence interval (CI) 0.63-1.10; P = 0.1909]. However, observed baseline imbalances indicated worse prognosis in the erlotinib arm. After adjustment for baseline characteristics, a significant PFS benefit for erlotinib was observed (HR 0.68; 95% CI 0.50-0.91; P = 0.0102). Exploratory biomarker analyses showed patients with high baseline serum amphiregulin levels might benefit from erlotinib. CONCLUSION: This study in patients with inoperable pancreatic cancer did not identify any prespecified biomarkers predictive of PFS benefit with erlotinib. Exploratory analyses suggested high amphiregulin might predict PFS benefit from erlotinib. CLINICALTRIALSGOV NUMBER: NCT00674973.

Nanoscale layering of antiferromagnetic and superconducting phases in Rb(2)Fe(4)Se(5) single crystals.

We studied phase separation in the single-crystalline antiferromagnetic superconductor Rb(2)Fe(4)Se(5) (RFS) using a combination of scattering-type scanning near-field optical microscopy and low-energy muon spin rotation (LE-µSR). We demonstrate that the antiferromagnetic and superconducting phases segregate into nanometer-thick layers perpendicular to the iron-selenide planes, while the characteristic in-plane size of the metallic domains reaches 10 µm. By means of LE-µSR we further show that in a 40-nm thick surface layer the ordered antiferromagnetic moment is drastically reduced, while the volume fraction of the paramagnetic phase is significantly enhanced over its bulk value. Self-organization into a quasiregular heterostructure indicates an intimate connection between the modulated superconducting and antiferromagnetic phases.

Neuroendocrine tumours of the gallbladder: three cases and a review of the literature.

Primary neuroendocrine tumours (NETs) of the gallbladder are rare. In the absence of any randomised controlled trials or prospective case series, we sought trends for clinical presentation and management based on 60 patients from published literature over the last 15 years, as well as three patients from our experience, and categorised them into various subgroups according to the WHO classification for NETs. Well-differentiated NETs have an indolent course and better prognosis. Poorly differentiated neuroendocrine carcinomas, which may be of large-cell or small-cell type and may coexist with other types of carcinoma, have a poor outcome. A variety of surgical and chemotherapeutic approaches have been adopted. Surgical excision appears to prolong life, with chemotherapy perhaps adding a marginal advantage.

A clinical study assessing the tolerability and biological effects of infliximab, a TNF-alpha inhibitor, in patients with advanced cancer.

BACKGROUND: Tumour necrosis factor-alpha (TNF-alpha) is an important regulator of the chronic inflammation contributing to tumour progression. Infliximab, an anti-TNF-alpha monoclonal antibody was investigated in this trial of patients with advanced cancer. The primary objectives were to determine the safety profile and biological response of infliximab in a cancer population. Clinical response was a secondary objective. PATIENTS AND METHODS: Forty-one patients received infliximab at 5 mg/kg (n = 21) or 10 mg/kg (n = 20) i.v. at 0 and 2 weeks and then every 4 weeks. Post-treatment samples were measured for changes in plasma and serum TNF-alpha, CCL2, IL-6 and C-reactive protein (CRP). RESULTS: Infliximab was well tolerated with no dose-limiting toxic effects. At both doses of infliximab, neutralisation of serum TNF-alpha was observed after 1 h while plasma CCL2, IL-6 and serum CRP were decreased 24 and 48 h following infliximab administration. Seven patients experienced disease stablisation (range 10-50+ weeks). There was no evidence of disease acceleration in any patient. CONCLUSIONS: Infliximab treatment was safe and well tolerated in patients with advanced cancer. There was evidence of biological activity with baseline TNF-alpha and CCL2 being correlated with infliximab response.

The protein kinase C inhibitor CGP41251 suppresses cytokine release and extracellular signal-regulated kinase 2 expression in cancer patients.

Components of cell signaling pathways provide important targets for anticancer drugs. Protein kinase C (PKC) is a serine/threonine-specific kinase that regulates cell growth and differentiation. It is also implicated in tumor promotion. The staurosporine analogue CGP41251 is a PKC inhibitor, and it is currently in a Phase I clinical trial for treatment of advanced cancer. However, it is difficult to define its biological activity. We have used two approaches to measure the in vivo biological response to CGP41251: (a) sequential whole blood samples were taken from 27 patients before and during treatment and incubated with mitogen (PHA), and cytokine [tumor necrosis factor (TNF)-alpha and interleukin (IL)-6] release was measured ex vivo; and (b) peripheral blood lymphocytes were isolated from seven of these patients, and the levels of extracellular signal-regulated kinase 2 were measured by Western blotting. Response to PHA was significantly lowered during treatment (P < 0.001 for TNF-alpha production; P < 0.03 for IL-6). This was most evident at 7 and 28 days after the start of treatment in patients receiving higher doses (150-300 mg/day; P = 0.002 and P = 0.02, respectively, for TNF-alpha and P = 0.001 and P = 0.003, respectively, for IL-6 release). Whole blood cytokine production returned to pretreatment levels after drug administration ceased. The levels of extracellular signal-regulated kinase 2 were reduced by 50-97% during treatment in all seven patients tested. These results show for the first time that a PKC inhibitor can block in vivo signaling pathways in cancer patients. The assays we describe complement toxicity studies in selecting relevant doses for Phase II trial of novel agents, particularly when biological activity occurs at doses below those that cause obvious side effects.

Weak-coupling superconductivity in a strongly correlated iron pnictide.

Iron-based superconductors have been found to exhibit an intimate interplay of orbital, spin, and lattice degrees of freedom, dramatically affecting their low-energy electronic properties, including superconductivity. Albeit the precise pairing mechanism remains unidentified, several candidate interactions have been suggested to mediate the superconducting pairing, both in the orbital and in the spin channel. Here, we employ optical spectroscopy (OS), angle-resolved photoemission spectroscopy (ARPES), ab initio band-structure, and Eliashberg calculations to show that nearly optimally doped NaFe0.978Co0.022As exhibits some of the strongest orbitally selective electronic correlations in the family of iron pnictides. Unexpectedly, we find that the mass enhancement of itinerant charge carriers in the strongly correlated band is dramatically reduced near the Γ point and attribute this effect to orbital mixing induced by pronounced spin-orbit coupling. Embracing the true band structure allows us to describe all low-energy electronic properties obtained in our experiments with remarkable consistency and demonstrate that superconductivity in this material is rather weak and mediated by spin fluctuations.

Use of positron emission tomography in pharmacokinetic studies to investigate therapeutic advantage in a phase I study of 120-hour intravenous infusion XR5000.

PURPOSE: XR5000 (N-[2-(dimethylamino)ethyl]acridine-4-carboxamide) is a topoisomerase I and II inhibitor. Because the cytotoxicity of XR5000 increases markedly with prolonged exposure, we performed a phase I study of weekly XR5000 by 120-hour continuous infusion over 3 weeks. PATIENTS AND METHODS: Twenty-four patients with advanced solid cancer were treated at seven dose levels (700 to 4,060 mg/m2/120 hrs) for a total of 67 cycles. Three patients underwent positron emission tomography (PET) studies at the maximum-tolerated dose (MTD) to evaluate normal tissue and tumor carbon-11 radiolabeled XR5000 ([11C]XR5000) pharmacokinetics. RESULTS: The dose-limiting toxicity was National Cancer Institute Common Toxicity Criteria (version 1) grade 4 chest and abdominal pain affecting the single patient receiving 4,060 mg/m2/120 hours, and the MTD was 3,010 mg/m2/120 hours. Other grade 3-4 toxicities, affecting single patients at the MTD, were myelosuppression (grade 4), raised bilirubin, vomiting, and somnolence (all grade 3). There was one partial response (adenocarcinoma of unknown primary); the remainder had progressive disease. [11C]XR5000 distributed well into the three tumors studied by PET. Tumor uptake (maximum concentration or area under the concentration versus time curve [AUC]) was less than in normal tissue in which the tumors were located. Tumor exposure (AUC; mean +/- SD in m2/mL/sec) increased when [(11)C]XR5000 was administered during an infusion of XR5000 (0.242 +/- 0.4), compared with [11C]XR5000 given alone (0.209 +/- 0.04; P <.05), indicating that tumor drug exposure was not saturated [corrected]. CONCLUSION: The recommended dose for XR5000 in phase II studies is 3,010 mg/m2/120 hours. PET studies with 11C-labeled drug were feasible and demonstrated in vivo distribution into tumors. Saturation of tumor exposure was not reached at the MTD.

Phase I and pharmacokinetic study of PKC412, an inhibitor of protein kinase C.

PURPOSE: N-Benzoyl staurosporine (PKC412) is a protein kinase C inhibitor with antitumor activity in laboratory models. We determined the toxicity of oral PKC412 administered daily for repeat cycles of 28 days. PATIENTS AND METHODS: Thirty-two patients with advanced solid cancers were treated at seven dose levels (12.5 to 300 mg daily) for a total of 68 cycles. RESULTS: The most frequent treatment-related toxicities were nausea, vomiting, fatigue, and diarrhea. At the two top dose levels (225 and 300 mg/d), 15 of 16 patients experienced nausea/vomiting (common toxicity criteria [CTC], version 1), grade 2 in nine of 16 and grade 3 in three of 16 patients; and six of 16 patients developed CTC grade 2 diarrhea. After 1 month of treatment, there were significant reductions in circulating lymphocyte (P <.02) and monocyte (P <.01) counts in patients receiving doses > or = 100 mg/d. Nevertheless, only two patients developed myelosuppression (both grade 2). Of two patients with progressive cholangiocarcinoma, one attained stable disease lasting 4.5 months and one a partial response lasting 4 months. There was a linear relationship between PKC412 dose and area under the curve (0-24 hours) and maximum plasma concentration with marked interpatient variability. The estimated median elimination half-life was 1.6 days (range, 0.9 to 4.0 days), and a metabolite with a median half-life of 36 days was detected. Steady-state PKC412 plasma levels at the top three dose cohorts (150 to 300 mg) were five to 10 times the cellular 50% inhibitory concentration for PKC412 of 0.2 to 0.7 micromol/L. CONCLUSION: PKC412 can be safely administered by chronic oral therapy, and 150 mg/d is suitable for phase II studies. The pharmacokinetics and lack of conventional toxicity indicate that pharmacodynamic measures may be additionally needed to optimize the drug dose and schedule.

Phase I study of the novel cyclic AMP (cAMP) analogue 8-chloro-cAMP in patients with cancer: toxicity, hormonal, and immunological effects.

The cyclic AMP (cAMP)-dependent protein kinase regulatory subunit RI is overexpressed in cancer cells. 8-Chloro-cAMP (8-Cl-cAMP) is an RII site-specific analogue that down-regulates RI and inhibits the growth of a wide range of cancer cells in vitro and in vivo. We performed a Phase I trial of 8-Cl-cAMP in 32 patients with malignancies that were refractory to standard treatments. 8-Cl-cAMP was initially given in a 1-month cycle by constant infusion at 0.005 mg/kg/h for 21 days, followed by 1 week of rest. The dose was escalated to 0.045 mg/kg/h, but hypercalcemia became the dose-limiting toxicity. The length of drug administration was, therefore, reduced to 5 days per week for the first 3 weeks of the cycle, but it was not possible to increase the drug dose without producing hypercalcemia. Hence, the length of drug administration was reduced to 3 days per week for the first 3 weeks of the cycle. The maximum tolerated dose for this regimen was 0.15 mg/kg/h, and the dose-limiting toxicities were reversible hypercalcemia and hepatotoxicity. Stable disease for > or =4 months was observed in two patients treated at > or =0.045 mg/kg. cAMP-dependent protein kinase is involved in hormone- and cytokine-mediated signaling, and so representative hormone, cytokine, and peripheral lymphocyte subsets were measured. The drug had a parathyroid hormone-like effect on calcium homeostasis and significantly increased circulating luteinizing hormone and 17-hydoxyprogesterone levels (P < 0.02 and P < 0.0006, respectively). We conclude that 8-Cl-cAMP is well tolerated without attendant myelotoxicity, and in this study, it was associated with biological effects. In Phase II studies, a dose of 0.11 mg/kg/h for 3 days per week would be appropriate.

A phase II study of razoxane, an antiangiogenic topoisomerase II inhibitor, in renal cell cancer with assessment of potential surrogate markers of angiogenesis.

Renal cell carcinoma (RCC) is an angiogenic tumor resistant to standard cytotoxic chemotherapeutic agents. Although often responsive to immunomodulatory agents including interleukin 2 and IFN-alpha, the overall results in randomized Phase III studies are disappointing with only modest improvements in overall survival. This Phase II study evaluated the efficacy and tolerability of razoxane, an antiangiogenic topoisomerase II inhibitor, in 40 patients (32 men, 8 women; age: range, 31-76 years; median, 58 years) with inoperable RCC. Twenty patients received razoxane 125 mg p.o., twice a day for 5 days each week for 8 weeks (one cycle). This was repeated in patients with stable disease (StD), but was discontinued after 16 weeks if there was no evidence of an objective response. Because minimal toxicity was seen, subsequent patients (n = 20) were treated until progressive disease (PD) was documented. Of 38 evaluable patients, 11 (29%) had StD for a minimum of 4 months, and the remainder had PD. Median overall survival was 7.3 months. Duration of survival was significantly better in patients with StD compared with those with PD (P = 0.003). The effect of treatment on six potential surrogate serum/plasma (vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), urokinase plasminogen activator soluble receptor (uPAsr), E-selectin, vascular cell adhesion molecule-1 (VCAM-1) and von Willebrand's factor (vWF) and two urinary (VEGF and bFGF) markers of angiogenesis was evaluated before and after 1 cycle of treatment. Pretreatment serum VEGF and E-selectin levels above the median value were associated with a poor prognosis. Serum VCAM-1 levels and urinary VEGF levels rose significantly after one cycle in patients with PD but not in those with StD. Serum VEGF, bFGF, VCAM-1 and vWF, plasma uPAsr and urinary bFGF levels were significantly higher in PD patients compared with StD patients before and/or after 1 cycle of treatment. In conclusion, razoxane is an antiangiogenic agent that has minimal toxicity and that requires further evaluation in combination with other active agents in the treatment of RCC. Surrogate serum and urinary markers of angiogenesis may have a role to play in predicting disease response and overall survival in RCC.

Phase I and pharmacological study of the oral matrix metalloproteinase inhibitor, MMI270 (CGS27023A), in patients with advanced solid cancer.

This Phase I study of MMI270, an p.o. administered matrix metalloproteinase inhibitor, assessed toxicity, pharmacokinetics, and tumor response data and investigated markers of biological activity to recommend a dose for Phase II studies. MMI270 was administered continuously at seven dose levels (50 mg once daily to 600 mg three times/day). Patients were evaluated for toxicity and tumor response, and blood and urine samples were taken for pharmacokinetics, bone resorption markers, direct targets of the inhibitor [matrix metalloproteinase-2 (MMP-2), MMP-8, and MMP-9], indirect targets [tissue inhibitor of metalloproteinase-1 (TIMP-1), TIMP-2, basic fibroblast growth factor, vascular endothelial growth factor, vascular cell adhesion molecule-1, soluble urokinase plasminogen activator receptor, and cathepsins B and H] and for a tumor necrosis factor-alpha cytokine release assay. Ninety-two patients were entered. There was no myelotoxicity. Eighteen patients developed a widespread maculopapular rash, which increased in frequency and severity at doses > or = 300 mg bid. Thirty nine patients developed musculoskeletal side effects, which were related to duration of treatment, not to dose level. Pharmacokinetics were linear, and MMI270 was rapidly absorbed and eliminated with minimal accumulation on chronic dosing. Sustained plasma concentrations in excess of 4 x mean IC(50) for the target enzymes were observed at dose levels > or = 150 mg bid. There were no tumor regressions; however, 19 patients had stable disease for > or = 90 days. There was a dose-response increase of MMP-2 and TIMP-1 with MMI270. Transient effects on the bone resorption markers were detected. MMI270 was generally well tolerated, with adequate plasma levels for target enzyme inhibition. The two main toxicities were rash, resulting in a maximum tolerated dose of 300 mg bid and musculoskeletal side effects. Biological marker data indicate drug effects. The rise in TIMP-1 suggests that a reflex rise in inhibitors could modify the effects of MMI270. The recommended Phase II dose is 300 mg bid.

Glomerulotubular function in long-term renal allograft recipients. A comparison of conventional therapy with cyclosporine.

Glomerular and tubular function were assessed, using a lithium clearance technique, in two groups of renal allograft recipients at least one year after transplantation. Group 1 comprised 14 patients receiving low-dose prednisolone and cyclosporine, and group 2, 14 patients receiving low-dose prednisolone and azathioprine. There were no significant differences in creatinine clearances between the two groups, although the clearances of lithium (which is absorbed almost exclusively from the proximal tubule) and sodium were significantly lower in the cyclosporine-treated group. Fractional lithium excretion was also significantly lower in group 1 than in group 2, but there was no significant difference in fractional sodium excretion. The absolute proximal reabsorption of sodium and water did not differ between the groups, although the fractional proximal reabsorption of sodium and water was significantly higher in group 1. In contrast, the distal reabsorption of sodium and of water was significantly lower in the cyclosporine-treated patients than in the azathioprine-treated patients; there were, however, no significant differences in the distal fractional reabsorptions of sodium and water between the two groups. In addition there was no correlation in group 1 between whole-blood cyclosporine levels or time since transplantation and any of the assessed parameters of renal function. These results indicate that tubular concentrating abnormalities in cyclosporine-treated renal allograft recipients are similar to those observed in rodent models of cyclosporine nephrotoxicity. They suggest that the pathogenesis of cyclosporine nephrotoxicity may be similar in renal allograft recipients to that in experimental models.

Immune responses to noninherited maternal RT1A antigens in inbred rats.

Humoral responses to non-inherited maternal class I antigens (class I NIMAs) were assessed in 3 groups of inbred rats expressing the RT1u phenotype. Group 1 consisted of the progeny of (AO X DA)F1 X PVG matings; their haplotype was RT1u/c and their non-inherited maternal haplotype RT1a. Group 2 were the progeny of (AO X LEW)F1 X PVG matings the haplotype of which was also RT1u/c, but their non-inherited maternal haplotype was RT1l. Group 3 comprised 8 (AO X PVG)F1 (RT1u/c) hybrids. All rats received 2 intravenous blood transfusions (0.5 ml) from male DA (RT1Aa) donors on days 0 and 7. They were bled at weekly intervals for 6 weeks and again at 20 weeks after the first transfusion. Alloantibody responses to RT1Aa were assessed by an indirect hemagglutination assay (IHA)* and by a 51Chromium-release complement-dependent red cell cytotoxicity assay. All groups exhibited vigorous anti-class I antibody responses to the DA transfusions. No significant differences were detected, however, in antibody titers between the groups either by IHA or CDC or in the rates of decay of antibody titers up to week 20. In addition no blocking activity was found in sera obtained on day 0 from group 1 animals and tested for antiidiotypic antibody activity to cytotoxic anti-RT1Aa antibodies. In order to assess whether suppressor activity had been activated by the initial transfusions, in the animals in which class I NIMA was RT1Aa, all groups were rechallenged with a DA transfusion at week 20. All animals exhibited vigorous anamnestic responses to this challenge and no significant differences were detected between groups. In order to determine whether cellular tolerance to the noninherited maternal haplotype was present in group 1 animals, proliferative responses were assessed by one-way mixed lymphocyte cultures, using DA lymph node stimulator cells. No significant differences were detected in proliferative or kinetic responses between lymph node cells from rats the noninherited maternal haplotype of which was RT1a or from naive (AO X PVG)F1 hybrids. Peak proliferative responses to DA cells in rats the noninherited maternal haplotype of which was RT1l were similar, but maximal on day 4 as opposed to day 3. Hence in these inbred rat strains no evidence of humoral tolerance to class I NIMAs was detected. In addition there was no evidence of cellular tolerance to the noninherited maternal MHC haplotype.

The effects of rapamycin on humoral immunity in vivo. Suppression of primary responses but not of ongoing alloantibody synthesis or memory responses.

The effect of rapamycin on primary and secondary alloantibody responses to major histocompatibility complex class I antigens was investigated in inbred rat strains. Primary anti-MHC class I alloantibody responses, detected by indirect hemagglutination and complement-dependent cytotoxicity assays, were abrogated in high-responder WAG (RT1u) recipients of DA (RT1a) blood transfusions, given on days 0 and 7 of a 14-day course of rapamycin (3 mg/kg/day). Antibody class studies showed that both IgM and IgG responses were equally effectively inhibited. Moreover, when these animals were rechallenged with DA transfusions, 28 days after drug withdrawal, they exhibited donor-specific humoral unresponsiveness. Similar results were observed in cyclosporine-treated rats. In preimmunized high-responder LEW (RT1(1)) rats with high titer anti-DA class I alloantibodies, a 35-day course of rapamycin (3 mg/kg/day) had no significant suppressive effect on serum alloantibody levels when compared with untreated preimmunized control animals. WAG rats were immunized by DA transfusions and serum antibody levels then allowed to decay over 16 weeks. The animals were then challenged with a further DA transfusion given on the second day of a 14-day course of rapamycin (3 mg/kg/day). Alloantibody responses to the challenge transfusion in this group were not, however, significantly suppressed when compared with a non-drug-treated control group. The results of this study indicate that rapamycin is a potent inhibitor of primary alloantibody synthesis in high-responder rat strains, but does not significantly suppress alloantibody synthesis in animals with established humoral reactivity. These results may be of relevance if rapamycin is to be used in clinical renal transplantation, because in man similar antibodies mediate hyperacute rejection, and when they develop after transplantation are associated with very high rates of rejection.

FK506--its influence on anti-class 1 MHC alloantibody responses to blood transfusions.

The influence of FK506 on in vivo alloantibody responses to major histocompatability class 1 antigens was investigated in inbred rat strains, and compared with the effect of cyclosporine. AO rats received transfusions of DA blood on days 0 and 7. From days 0 to 14 the rats also received, daily, either FK506 0.3 mg/kg suspended in saline or dissolved in olive oil, or CsA 10 mg/kg. The administration of FK506 suspended in saline at the time of blood transfusion completely abrogated the development of anti-MHC class 1 alloantibodies as detected by indirect hemagglutination (IHA)* and 51Cr release complement dependent cytotoxicity assays (CDC). Isotyping studies showed that FK506 suspended in saline suppressed IgM production and inhibited the switch to IgG production. Similar responses were seen in CsA-treated animals. In contrast, rats treated with FK506 dissolved in olive oil developed high titers of anti-class 1 alloantibodies. On days 49 and 56 the rats were challenged with further DA blood transfusions given without immunosuppression. In the groups given FK506 suspended in saline or CsA, cytotoxic antibodies did not develop; low titer antibodies were, however, detected by IHA in the animals that had previously received FK506 suspended in saline. The results indicate that FK506, in common with CsA, inhibits anti-class 1 MHC alloantibody production, and at the same time enables the development of tolerance. The vehicle in which FK506 is administered is, however, critical to its efficacy at the low doses used. These results may be of relevance to clinical transplantation as similar antibodies mediate hyperacute renal allograft rejection in man.

Reduction of sensitization induced by blood transfusion in the rat by monoclonal antibodies.

Primary and secondary alloantibody responses were monitored in (AOxPVG)F1 hybrid rats after three transfusions of DA blood; the initial transfusion was either untreated or pretreated with monoclonal antibody directed to class I antigens or other cell surface markers. Mean antibody activity in recipient sera against class I DA antigens was significantly decreased by pretreatment with the monoclonal antibodies. The most marked suppression was associated with pretreatment by antibodies to the four major nonoverlapping epitopes of the RT1Aa antigen. Subsequent transfusions of DA blood failed to stimulate a secondary response. Crossreactivity of the alloantibody reactivity with BDIX antigens was diminished by pretreating the transfusions with rat anti-RT1A antibodies and, to a lesser extent, with a mouse monoclonal antibody (OX-18) to a common class I determinant. Monoclonal antibody pretreatment had no effect on the humoral response to class II DA antigens. These studies indicate that blood transfusions pretreated with monoclonal antibodies induce a less-potent cytotoxic humoral immune response and that reactivity is most effectively suppressed by completely masking the class I antigen. This technique may prove of clinical value in preventing the sensitization caused by blood transfusions in potential transplant recipients.

Immunological aspects of clinical renal transplantation.

Improved facilities for treating patients with end-stage renal failure have resulted in more elderly and debilitated patients being accepted for treatment. Renal transplantation is now the optimum form of treatment but organ procurement has failed to match clinical demand. Future developments may focus on further non-specific immunosuppressive agents. As one year survival rates for first cadaver allografts now exceed 85% in many units, the significance of new developments will be increasingly difficult to evaluate.

Evaluation of the alkaline comet assay and urinary 3-methyladenine excretion for monitoring DNA damage in melanoma patients treated with dacarbazine and tamoxifen.

PURPOSE: To develop, using dacarbazine as a model, reliable techniques for measuring DNA damage and repair as pharmacodynamic endpoints for patients receiving chemotherapy. METHODS: A group of 39 patients with malignant melanoma were treated with dacarbazine 1 g/m(2) i.v. every 21 days. Tamoxifen 20 mg daily was commenced 24 h after the first infusion and continued until 3 weeks after the last cycle of chemotherapy. DNA strand breaks formed during dacarbazine-induced DNA damage and repair were measured in individual cells by the alkaline comet assay. DNA methyl adducts were quantified by measuring urinary 3-methyladenine (3-MeA) excretion using immunoaffinity ELISA. Venous blood was taken on cycles 1 and 2 for separation of peripheral blood lymphocytes (PBLs) for measurement of DNA strand breaks. RESULTS: Wide interpatient variation in PBL DNA strand breaks occurred following chemotherapy, with a peak at 4 h (median 26.6 h, interquartile range 14.75-40.5 h) and incomplete repair by 24 h. Similarly, there was a range of 3-MeA excretion with peak levels 4-10 h after chemotherapy (median 33 nmol/h, interquartile range 20.4-48.65 nmol/h). Peak 3-MeA excretion was positively correlated with DNA strand breaks at 4 h (Spearman's correlation coefficient, r=0.39, P=0.036) and 24 h (r=0.46, P=0.01). Drug-induced emesis correlated with PBL DNA strand breaks (Mann Whitney U-test, P=0.03) but not with peak 3-MeA excretion. CONCLUSIONS: DNA damage and repair following cytotoxic chemotherapy can be measured in vivo by the alkaline comet assay and by urinary 3-MeA excretion in patients receiving chemotherapy.