Stromal antigen targeting by a humanised monoclonal antibody: an early phase II trial of sibrotuzumab in patients with metastatic colorectal cancer

BACKGROUND

A novel immunological approach to colon cancer therapy is the antibody targeting of the fibroblast activation protein (FAP), which is highly expressed by stroma cells of this tumour. Unconjugated sibrotuzumab (BIBH 1), which is a humanised version of the murine anti-FAP mAb F19, was investigated for its anti-tumour activity, safety and pharmacokinetics.

PATIENTS AND METHODS

Patients with metastatic colorectal cancer received weekly intravenous infusions of unconjugated sibrotuzumab at a dose of 100 mg over 12 scheduled weeks. The study was implemented as an open-label, uncontrolled, multicentre trial.

RESULTS

25 patients were enrolled. Patients had one or more measurable lesions, predominantly liver lesions, at baseline. At least 8 repeated weekly infusions of sibrotuzumab in 17 evaluable patients did not result in complete or partial remission. Rather, ongoing tumour progression was noted in all patients except for 2 patients with stable disease. However, progressive disease was also observed post-study in these 2 patients who received 1 and 6 additional infusions, respectively, of sibrotuzumab. Sibrotuzumab exhibited 2-compartment pharmacokinetics with a dominant terminal phase and t1/2 beta = 5.3 +/- 2.3 days. Adverse drug reactions (rigors/chills, nausea, flushing and one incidence of bronchospasm) were observed in 5 patients. Of the 24 patients given 2 or more infusions of sibrotuzumab, antibodies against sibrotuzumab were found in 3 patients (12.5%) after 4-12 infusions.

CONCLUSIONS

Sibrotuzumab was well tolerated and safe. The minimal requirement for the continuation of this exploratory trial, of at least one complete or partial remission, or equivalently, of 4 patients with stable disease, was not met.

Treatment of steroid-resistant acute graft-versus-host disease with daclizumab and etanercept

Steroid-resistant acute GVHD (aGVHD) following allogeneic hematopoietic stem cell transplantation (alloHSCT) continues to be associated with a high mortality. We report the results of a phase II study of treatment of steroid-resistant aGVHD with the IL-2 receptor antibody daclizumab combined with the TNF-receptor fusion protein etanercept. Treatment consisted of daclizumab 1 mg/kg given i.v. on days 1, 4, 8, 15, 22 and etanercept 16 mg/m(2) s.c. on days 1, 5, 9, 13, 17. A total of 21 patients (age 15-61 years) with steroid-resistant aGVHD after alloHSCT were included in the study. Donor types were HLA-matched related (n=6), HLA-matched unrelated (n=14), and HLA-mismatched unrelated (n=1). Eight patients achieved complete, and six showed partial remission of aGVHD. Seven patients did not respond. Four of 21 patients are currently alive with a median follow-up of 586 (185-1155) days. Three patients died due to relapsed malignancy. Treatment-related mortality was due to infectious complications (n=11) or organ failure due to aGVHD (n=3). In total, 12 patients developed subsequent chronic GVHD. In conclusion, the data demonstrate an acceptable response rate of the combination of daclizumab and etanercept in the treatment of steroid-resistant aGVHD. Nevertheless, long-term mortality due to infectious complications and chronic GVHD remains high.

Pre-clinical evaluation of a methotrexate-albumin conjugate (MTX-HSA) in human tumor xenografts in vivo

Methotrexate covalently bound to human serum albumin in a 1:1 molar ratio (MTX-HSA) is a new macromolecular drug which is currently being studied in phase I clinical trials by the German Association for Medical Oncology (AIO) Phase I/II study group. Previous studies have shown that MTX-HSA differs favorably from unbound MTX in terms of plasma half-life time, tumor accumulation of albumin and uptake mechanisms into cancer cells. To achieve optimal drug efficacy, repeated treatment cycles were necessary. To evaluate the anti-tumor activity of MTX-HSA and MTX in pre-clinical in vivo models, we selected 7 solid human tumor xenografts growing s.c. in nude mice and administered drug either i.p. or i.v. weekly for 3 weeks. The maximal tolerated dose (MTD) of MTX-HSA in nude mice was 12.5 mg/kg given i.p. on days 1, 8 and 15, whereas the MTD for free MTX was 100 mg/kg given i.v. MTX-HSA was significantly more active (p > 0.01) than MTX in 3 models. In the soft tissue sarcoma SXF 1301, MTX-HSA effected complete remission/cure after a single injection, whereas free MTX resulted in short-lasting, partial tumor regression. In the prostate-cancer model PRXF PC3M, MTX-HSA produced growth inhibition of 92.8% of control or an optimal test/control (T/C) of 7.2% compared to a T/C of 20.8% for MTX (p = 0.05). In the osteosarcoma model SXF 1410, optimal T/C values were 10.2% and 14.5%, respectively (p = 0.025). In lung cancers LXFE 409 and LXFL 529, bladder cancer BXF 1258 and breast cancer MAXF 449, both compounds were inactive. The improved therapeutic effects seen in 3 xenograft models under MTX-HSA treatment are promising and might be due to specific accumulation of the compound in solid tumors owing to their enhanced permeability and retention effect. Thus, clinical development of MTX-HSA will continue and sarcomas as well as prostate cancers will be included as potential target tumors for upcoming clinical phase II trials.

Pharmacokinetics of methotrexate-albumin conjugates in tumor-bearing rats

Linking chemotherapeutic drugs to a macromolecular carrier system may enhance tumor targeting, reduce toxicity and overcome drug resistance mechanisms. As an elementary model to evaluate the pharmacological properties of macromolecular drug carrier systems we chose rat serum albumin (RSA) for carrier and methotrexate (MTX) as antineoplastic drug. The conjugation procedure yielded conjugates with an approximate 1:1 molar loading rate (MTX(1)-RSA). In the first part of the study a residualizing [111In]DTPA protein label was used for mapping in vivo the catabolic sites of the native carrier protein and of the MTX(1)-RSA drug conjugate in Walker 256 carcinosarcoma bearing rats. The tumor accumulation was about 14% of the injected dose for the RSA and MTX(1)-RSA tracers after 24 h. Tracer entrapment by organs with an active mononuclear phagocyte system was low (liver below 7% and spleen below 1.5% of the injected dose after 24 h). The 1:1 conjugation of MTX to RSA did not decisively alter the pharmacokinetic properties nor the tumor or tissue distribution of the native carrier protein RSA. In the second part of the study the different properties of the MTX(1)-RSA conjugate were compared with MTX in vivo. About 2 mg MTX/kg body weight either of the drug conjugate or of the original drug were injected after being additionally spiked with radiolabeled tracers. Plasma concentrations were simultaneously determined by immunological and radioactive means. After 24 h about 12% MTX(1)-RSA was found in circulation compared to 0.03% MTX. Favorable tumor accumulation rates of about 14% were achieved for MTX(1)-RSA versus 0.04% for MTX. About 45-fold more of the injected dose of [3H]MTX accumulated in the liver as compared to the tumor (1.5 versus 0.03%) after 24 h. Conjugation of MTX to RSA reversed this ratio in favor of the tumor to 1:1.4 (13.6 versus 9.6%). In conclusion, the potential therapeutic benefit of the MTX(1)-RSA conjugate lies in its very long tumor exposure time and its improved tumor accumulation rate compared to conventional MTX. In addition the conjugation to albumin might enhance the therapeutic effects over those achieved by long-term continuous infusion of MTX, as MTX(1)-RSA enters the cells by a different uptake mechanism. This might also help to circumvent MTX resistance mechanisms, such as a reduction in folate receptor numbers or impaired MTX polyglutamylation.

Replacement of calcineurin inhibitors with daclizumab in patients with transplantation-associated microangiopathy or renal insufficiency associated with graft-versus-host disease

Transplantation-associated microangiopathy (TAM) or renal insufficiency (RI) after allogeneic hematopoietic stem cell transplantation is associated with a high mortality. As calcineurin inhibitors (CI) may contribute to TAM or RI, we evaluated the efficacy of replacing CI by daclizumab in patients with graft-versus-host disease (GVHD). Thirteen patients with GVHD-associated TAM and five patients with RI were treated with daclizumab 1 mg/kg intravenous (i.v.)/week, discontinuation of the CI and continuation of the remaining GVHD treatment. All patients had acute GVHD (steroid-sensitive (n=4), steroid-refractory (n=10)) or chronic GVHD (n=4) and were treated with CI before the start of daclizumab. Nine of 13 patients with TAM treated with daclizumab and discontinuation of CI achieved complete remission of TAM, two had stable disease, and one patient did not respond. Patients receiving daclizumab for RI without TAM showed stabilization (2/5) or improvement (3/5) of renal function. Four of 14 patients with acute GVHD achieved CR, two partial remission, eight patients did not respond and 11/14 died at a median of 39 days after start of the daclizumab. Our data demonstrate that replacement of CI by daclizumab can improve TAM and RI. However, mortality remains high in patients with acute GVHD.

Determination of molecules regulating gene delivery using adenoviral vectors in ovarian carcinomas

Gene therapeutic approaches currently favor adenoviral vectors over alternatively available vector systems. Ovarian cancer represents an attractive model for an intraperitoneal adenovirus-based gene therapy, which is now under intensive clinical investigation. Adenovirus-mediated gene transfer depends on adequate virus uptake and thus on the presence of sufficient amounts of high-affinity coxsackie-adenovirus receptor (CAR) and alphavbeta3- and alphavbeta5 integrins on target cells. This fact has been ignored in most ongoing clinical trials. This investigation, therefore, determined expression of CAR by immunohistochemistry in 37 ovarian carcinomas and compared it with that of alphavbeta3 and alphavbeta5 integrins. In all samples, except one undifferentiated carcinoma, CAR was immunohistochemically demonstrable. Grade 1 tumors exhibited stronger CAR immunostaining as compared with higher-grade cancers (P < 0.03). Integrins alphavbeta3 and alphavbeta5 were detectable in 62% and 65% of carcinomas, respectively, and staining for both classes correlated positively (P < 0.005). Cancers classified as undifferentiated completely lacked alphavbeta3 expression. Furthermore, in undifferentiated and grade 3 carcinomas the three molecules studied exhibited marked distributional heterogeneity with regard to focal positivity and negativity within the same tumor. Either the absence of CAR, alphavbeta3 and alphavbeta5 or the pronounced heterogeneity in their expression might seriously compromise the efficiency of adenovirus-based gene therapy in ovarian cancer.

A prospective randomised phase-II trial with gemcitabine versus gemcitabine plus sunitinib in advanced pancreatic cancer: a study of the CESAR Central European Society for Anticancer Drug Research-EWIV

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common malignant tumours and is still associated with a poor prognosis in advanced disease. To improve the standard therapy with gemcitabine, we initiated a prospective randomised phase-II trial with gemcitabine (GEM) versus gemcitabine plus sunitinib (SUNGEM) based on data of in vitro trials and phase-I data for the combination treatment. The rational of adding sunitinib was its putative antiangiogenic mechanism of action.

METHODS

A total of 106 eligible patients with locally advanced, unresectable or metastatic PDAC without previous system therapy were randomised to receive GEM at a dosage of 1.000mg/m(2) d1, 8, 15 q28 versus a combination of SUNGEM at a dosage of GEM 1.000mg/m(2) d1+8 and sunitinib 50mg p.o. d1-14, q21d. The primary end-point was progression free survival (PFS), secondary end-points were overall survival (OS), toxicity and overall response rate (ORR).

RESULTS

The confirmatory analysis of PFS was based on the intend-to-treat (ITT) population (N=106). The median PFS was 13.3 weeks (95% confidence interval (95%-CI): 10.4-18.1 weeks) for GEM and 11.6 weeks for SUNGEM (95%-CI: 7.0-18.0 weeks; p=0.78 one-sided log-rank). The ORR was 6.1% (95%-CI: 0.7-20.2%) for GEM and for 7.1% (95%-CI: 0.9-23.5%) for SUNGEM (p=0.87). The median time to progression (TTP) was 14.0 weeks (95%-CI: 12.4-22.3 weeks) for GEM and 18.0 weeks (95%-CI: 11.3-19.3 weeks) for SUNGEM (p=0.60; two-sided log-rank). The median OS was 36.7 weeks (95%-CI: 20.6-49.0 weeks) for the GEM arm and 30.4 weeks (95%-CI: 18.1-37.6 weeks) for the SUNGEM (p=0.78, one-sided log-rank). In regard to toxicities, suspected SAEs were reported in 53.7% in the GEM arm and 71.2% in the SUNGEM arm. Grade 3 and 4 neutropenia was statistically significantly higher in the SUNGEM arm with 48.1% versus 27.8% in the GEM arm (p=0.045, two sided log-rank).

CONCLUSIONS

The combination SUNGEM was not sufficient superior in locally advanced or metastatic PDAC compared to GEM alone in regard to efficacy but was associated with more toxicity.

Treatment of peripheral T-cell lymphomas (PTCL) with high-dose chemotherapy and autologous or allogeneic hematopoietic transplantation

Peripheral T-cell lymphomas (PTCL) are a rare entity of non-Hodgkin's lymphomas (NHL). Despite the poor outcome after conventional chemotherapy, the impact of high-dose chemotherapy (HDCT) and autologous or allogeneic stem cell transplantation is not well defined in these patients. In a retrospective study, we evaluated the outcome of 15 patients (9 male, 6 female) with PTCL after HDCT with autologous (10 patients) and allogeneic (5 patients) stem cell transplantation between 1996 and 2001 at our department. At the time of transplantation three patients were in second remission, seven patients were in partial remission (PR), and three patients had refractory disease. Two patients were treated with sequential HDCT (cyclophosphamide, adriamycin, vincristine, etoposide, prednisolone, m-CHOEP). The conditioning regimes were heterogeneous. After HDCT ten patients (67%, autologous 7, allogeneic 3) achieved CR, two patients (13%, autologous 2, allogeneic 0) had refractory disease, and three patients (20%, autologous 1, allogeneic 2) died because of toxic side effects before evaluation of response was performed. The median overall survival (OS) was 12 months. The 1-year probability of survival for the autologous and allogeneic groups was 58% and 40%, respectively. At the time of evaluation, six patients are alive and nine patients have died (four severe infection, one late toxicity, two disease progression, and two relapse). Despite the small number of patients in this study, HDCT with autologous or allogeneic hematopoietic transplantation seems to be an effective treatment option that can achieve CR for patients with PTCL. Because of the poor outcome of these patients after conventional chemotherapy, HDCT seems to be a rational option in first-line therapy. Whether it improves survival in these patients should be further investigated.

Adjuvant therapy with edrecolomab versus observation in stage II colon cancer: a multicenter randomized phase III study

BACKGROUND

In a phase III study recruiting patients with stage II colon cancer the effect of adjuvant therapy with edrecolomab, a murine monoclonal antibody to the cell-surface glycoprotein 17-1A, was compared to observation alone.

PATIENTS AND METHODS

From January 1997 until July 2000 a total of 377 patients were postoperatively stratified according to tumor stage (T3 vs. T4) and center, and randomly allocated to either treatment with edrecolomab (cohort A, n = 183) or observation (cohort B, n = 194). Patients in cohort A received a total of 900 mg edrecolomab. The study was terminated prematurely because of discontinuation of drug supply in Germany.

RESULTS

305 patients were eligible for the primary endpoint of overall survival and 282 patients for disease-free survival. After a median follow-up of 42 months overall survival and disease-free survival were not significantly different. Toxicity was mild.

CONCLUSIONS

In the present study, postoperative adjuvant treatment with edrecolomab in patients with resected stage II colon cancer did not improve overall or disease-free survival.

Antitumor activity of methotrexate-albumin conjugates in rats bearing a Walker-256 carcinoma

We have recently reported that albumin accumulates in solid tumors and serves there as a source of nitrogen and energy. Methotrexate-albumin conjugates [MTX(I)-RSA] derivatized at a molar ratio of 1:1 differ favorably from original MTX in terms of plasma presence and tumor uptake. The purpose of this study was to evaluate the therapeutic efficacy of these novel conjugates in a comparative study with low m.w. MTX is Sprague-Dawley rats bearing a Walker-256 carcinoma. The maximum tolerated dose (MTD) for MTX and MTX(I)-RSA was determined (2 mg/kg based on MTX injected on days 1, 3 and 8). The tumor-bearing rats received injections of either the MTD or MTD/2 of MTX, MTX-albumin or mixtures containing the MTD/2 or MTD/4 of both MTX and MTX-albumin. No toxic side effects were observed. Cure rate and tumor growth retardation were slightly better for the conjugate compared with MTX alone in the MTD group (16 complete remissions vs. 14 of 20 rats). The best results were achieved for the combination treatment with MTX and MTX-albumin, with complete remission in all 20 rats. In conclusion, MTX-albumin conjugates show therapeutic activity in vivo without toxic side effects. Additive effects were observed for a combination of MTX-albumin and MTX. These effects might be caused by the much longer tumor exposition time of the conjugate in conjunction with a different route of uptake (pinocytosis for MTX-albumin vs. folate receptors for MTX).

Mathematical synthesis of the cortical circulation for the whole mouse brain-part I. theory and image integration

Microcirculation plays a significant role in cerebral metabolism and blood flow control, yet explaining and predicting functional mechanisms remains elusive because it is difficult to make physiologically accurate mathematical models of the vascular network. As a precursor to the human brain, this paper presents a computational framework for synthesizing anatomically accurate network models for the cortical blood supply in mouse. It addresses two critical deficiencies in cerebrovascular modeling. At the microscopic length scale of individual capillaries, we present a novel synthesis method for building anatomically consistent capillary networks with loops and anastomoses (=microcirculatory closure). This overcomes shortcomings in existing algorithms which are unable to create closed circulatory networks. A second critical innovation allows the incorporation of detailed anatomical features from image data into vascular growth. Specifically, computed tomography and two photon laser scanning microscopy data are input into the novel synthesis algorithm to build the cortical circulation for the entire mouse brain in silico. Computer predictions of blood flow and oxygen exchange executed on synthetic large-scale network models are expected to elucidate poorly understood functional mechanisms of the cerebral circulation.

High-dose 5-fluorouracil / folinic acid in combination with three-weekly mitomycin C in the treatment of advanced gastric cancer. A phase II study

BACKGROUND

The 24-hour continuous infusion of 5-fluorouracil (5-FU) and folinic acid (FA) as part of several new multidrug chemotherapy regimens in advanced gastric cancer (AGC) has shown to be effective, with low toxicity. In a previous phase II study with 3-weekly bolus 5-FU, FA and mitomycin C (MMC) we found a low toxicity rate and response rates comparable to those of regimens such as ELF, FAM or FAMTX, and a promising median overall survival. In order to improve this MMC-dependent schedule we initiated a phase II study with high-dose 5-FU/FA and 3-weekly bolus MMC.

PATIENTS AND METHODS

From February, 1998 to September, 2000 we recruited 33 patients with AGC to receive weekly 24-hour 5-FU 2,600 mg/m(2) preceded by 2-hour FA 500 mg/m(2) for 6 weeks, followed by a 2-week rest period. Bolus MMC 10 mg/m(2) was added in 3-weekly intervals. Treatment given on an outpatient basis, using portable pump systems, was repeated on day 57. Patients' characteristics were: male/female ratio 20/13; median age 57 (27-75) years; median WHO status 1 (0-2). 18 patients had a primary AGC, and 15 showed a relapsed AGC. Median follow-up was 11.8 months (range of those surviving: 2.7-11.8 months).

RESULTS

32 patients were evaluable for response - complete remission 9.1% (n = 3), partial remission 45.5% (n = 15), no change 27.3% (n = 9), progressive disease 15.1% (n = 5). Median overall survival time was 10.2 months [95% confidence interval (CI): 8.7-11.6], and median progression-free survival time was 7.6 months (95% CI: 4.4-10.9). The worst toxicities (%) observed were (CTC-NCI 1/2/3): leukopenia 45.5/18.2/6.1, thrombocytopenia 33.3/9.1/6.1, vomitus 24.2/9.1/0, diarrhea 36.4/6.1/3.0, stomatitis 18.2/9.1/0, hand-foot syndrome 12.1/0/0. Two patients developed hemolytic-uremic syndrome (HUS).

CONCLUSIONS

High-dose 5-FU/FA/MMC is an effective and well-tolerated outpatient regimen for AGC (objective response rate 54.6%). It may serve as an alternative to cisplatin-containing regimens; however, it has to be considered that possibly HUS may occur.

Voxelized simulation of cerebral oxygen perfusion elucidates hypoxia in aged mouse cortex

Departures of normal blood flow and metabolite distribution from the cerebral microvasculature into neuronal tissue have been implicated with age-related neurodegeneration. Mathematical models informed by spatially and temporally distributed neuroimage data are becoming instrumental for reconstructing a coherent picture of normal and pathological oxygen delivery throughout the brain. Unfortunately, current mathematical models of cerebral blood flow and oxygen exchange become excessively large in size. They further suffer from boundary effects due to incomplete or physiologically inaccurate computational domains, numerical instabilities due to enormous length scale differences, and convergence problems associated with condition number deterioration at fine mesh resolutions. Our proposed simple finite volume discretization scheme for blood and oxygen microperfusion simulations does not require expensive mesh generation leading to the critical benefit that it drastically reduces matrix size and bandwidth of the coupled oxygen transfer problem. The compact problem formulation yields rapid and stable convergence. Moreover, boundary effects can effectively be suppressed by generating very large replica of the cortical microcirculation in silico using an image-based cerebrovascular network synthesis algorithm, so that boundaries of the perfusion simulations are far removed from the regions of interest. Massive simulations over sizeable portions of the cortex with feature resolution down to the micron scale become tractable with even modest computer resources. The feasibility and accuracy of the novel method is demonstrated and validated with in vivo oxygen perfusion data in cohorts of young and aged mice. Our oxygen exchange simulations quantify steep gradients near penetrating blood vessels and point towards pathological changes that might cause neurodegeneration in aged brains. This research aims to explain mechanistic interactions between anatomical structures and how they might change in diseases or with age. Rigorous quantification of age-related changes is of significant interest because it might aide in the search for imaging biomarkers for dementia and Alzheimer’s disease.

Brain function critically depends on the maintenance of physiological blood supply and metabolism in the cortex. Disturbances to adequate perfusion have been linked to age-related neurodegeneration. However, the precise correlation between age-related hemodynamic changes and the resulting decline in oxygen delivery is not well understood and has not been quantified. Therefore, we introduce a new compact, and therefore highly scalable, computational method for predicting the physiological relationship between hemodynamics and cortical oxygen perfusion for large sections of the cortical microcirculation. We demonstrate the novel mesh generation-free (MGF), multi-scale simulation approach through realistic in vivo case studies of cortical microperfusion in the mouse brain. We further validate mechanistic correlations and a quantitative relationship between blood flow and brain oxygenation using experimental data from cohorts of young, middle aged and old mouse brains. Our computational approach overcomes size and performance limitations of previous unstructured meshing techniques to enable the prediction of oxygen tension with a spatial resolution of least two orders of magnitude higher than previously possible. Our simulation results support the hypothesis that structural changes in the microvasculature induce hypoxic pockets in the aged brain that are absent in the healthy, young mouse.

Pseudomembranous tracheobronchial aspergillosis: a rare manifestation of invasive aspergillosis in a non-neutropenic patient with Hodgkin's disease

Pseudomembranous tracheobronchial aspergillosis coincident with systemic pulmonary aspergillosis represents a rare manifestation of fungal infection in immunocompromized hosts. We report on a patient with recurrent Hodgkin's disease, showing this infectious pattern after treatment with corticosteroids within the antineoplastic schedule, whereas neutropenia--the main risk factor for mold infections--had not occurred. An impaired number of helper T lymphocytes was merely detected as an additional, but hypothetical risk factor, when investigating the status of immunosuppression. Treated systemically with amphotericin B, the patient recovered quickly, although reported mortality rates are disastrous. What is crucial for the clinical management is an early diagnosis by bronchoscopy and cultural proof of the pathogen followed by an adequate antifungal treatment.

Adjuvant chemotherapy in stage III colon cancer with 5-fluorouracil and levamisole versus 5-fluorouracil and leucovorin

BACKGROUND

Adjuvant chemotherapy for colon cancer has been established during the past decade. From 1990 until recently treatment with 5- fluorouracil (5-FU) and levamisole (LEV) lasting 12 months was recommended as standard treatment. At the initiation of this study in 1993 improvement of adjuvant therapy was expected by the modulation of 5-FU with folinic acid (FA). Therefore, we decided to perform a prospective randomized multicenter trial to compare standard 5-FU/LEV to 5-FU/FA for either 6 or 12 months.

PATIENTS AND METHODS

Patients with stage III colon cancer after curative en bloc resection were randomized in 3 treatment groups: arm A (5-FU/LEV, weekly, 12 months), arm B (5-FU/FA, days 1-5, every 4 weeks, 12 months) and arm C (like B, 6 months).

RESULTS

Between March 1993 and November 1997, 180 patients were randomized into the study, 155 were eligible for further evaluation. The interim analysis in November 2000 showed no significant difference for recurrence and disease-free survival in arm B and C, therefore the data from both 5-FU/FA treatment arms (B+C) were combined for comparison with 5-FU/LEV-treatment (A). Most pronounced toxicity in all treatment arms was mild nausea, loss of appetite and leukopenia. A tendency for more diarrhea and stomatitis was observed in arm B+C. After a median follow-up of 36.2 months no significant difference was seen for disease free survival (p = 0.9) and overall survival (p = 1.0). 3-year recurrence rates were 39.6% in arm A and 39.1% in arm B+C, 3-year survival rates amounted to 74.1% in arm A and 74.9% in arm B+C.

CONCLUSION

Only a limited number of patients could be recruited in this study. The observed data support the results of other studies, which concluded that 6 months (or 12 months) treatment with 5-FU/FA is equivalent to 12 months treatment with 5-FU/LEV. Therefore the 6 months treatment with 5-FU/FA can be supported as standard for adjuvant therapy of stage III colon cancer.

Methotrexate-albumin conjugate causes tumor growth delay in Dunning R3327 HI prostate cancer-bearing rats

Based on the rationale of a preferred albumin uptake by tumors, conjugates comprising of rat serum albumin (RSA) as a drug carrier and of methotrexate (MTX) as chemotherapeutic drug were prepared. For a comparative study of MTX-RSA and MTX we chose a slow growing Dunning R3327 HI prostate cancer model. In a radiopharmacologic study blood kinetics and the tumor and organ distribution pattern of residualizingly labeled MTX-RSA were determined, and were found to be similar to that of residualizingly labeled RSA. The MTD was established for Copenhagen rats at a total four injections of 2 mg/kg MTX or MTX-RSA administered at days 0, 4, 8 and 12. Tumor volume measurements and tumor removal showed a small non-significant growth delay in the MTX treatment group, suggesting MTX resistance for the Dunning R3327 HI prostate carcinoma. In contrast, treatment with MTX-RSA resulted in a significant (50%) growth inhibition of the Dunning R3327 HI tumor. The cellular mechanisms responsible for MTX resistance in Dunning HI tumor cells is not known. The improved therapeutic effects seen during MTX-RSA treatment in this slow growing adenocarcinoma might be a result of prolonged tumor exposure time and an altered cellular uptake by a lysosomal route. MTX-albumin conjugates have shown antitumor activity exceeding that of MTX in several tumor xenografts in nude mice, including human prostate cancer. The recently initiated clinical development of MTX-human serum albumin will be continued and cancer of the prostate will be included as a potential target tumor during further clinical phase II testing.

Capecitabine in combination with mitomycin C in patients with gastrointestinal cancer: results of an extended multicentre phase-I trial

The aim of this study was to determine the dose-limiting toxicity (DLT) and establish the recommended dose for mitomycin C added every 3 weeks to the standard combination dose of capecitabine. Cohorts of at least three patients with pretreated gastrointestinal carcinoma received capecitabine 1000 mg m(-2) orally twice daily on days 1-14 plus i.v. bolus mitomycin C on day 1 at doses of 4, 6, 8 or 10 mg m(-2) (corresponding to dose levels I-IV). Cycles were repeated every 3 weeks. Two treatment cycles were considered for the evaluation of DLTs. Of the 53 patients enrolled, the majority had colorectal (n=27) or gastric (n=14) cancers. Patients had received a median of two lines of prior chemotherapy (34% with >/=3 lines and 87% with prior 5-FU-based therapy). At the recommended dose level (IV, n=30), grade 3 adverse events during cycles 1 and 2 were: anaemia (10%); leukopenia (3%); thrombocytopenia (3%); stomatitis/mucositis (3%); hand-foot syndrome (3%). Two patients experienced DLTs (mucositis, n=1; neutropenic fever, n=1), but there were no grade 4 events. The median dose intensity for capecitabine and mitomycin C was 100% during cycles 1 and 2 and only four patients required postponement of therapy. Of the 43 patients evaluable for efficacy, seven achieved partial and minor remissions (16%; 95% CI, 5-28%), and 12 patients (28%) had stable disease. The favourable safety profile and promising activity of the capecitabine/mitomycin C combination, even in heavily pretreated patients, warrant further evaluation in patients with advanced colorectal and gastric cancers.

Mathematical synthesis of the cortical circulation for the whole mouse brain-part II: Microcirculatory closure

Recent advancements in multiphoton imaging and vascular reconstruction algorithms have increased the amount of data on cerebrovascular circulation for statistical analysis and hemodynamic simulations. Experimental observations offer fundamental insights into capillary network topology but mainly within a narrow field of view typically spanning a small fraction of the cortical surface (less than 2%). In contrast, larger-resolution imaging modalities, such as computed tomography (CT) or magnetic resonance imaging (MRI), have whole-brain coverage but capture only larger blood vessels, overlooking the microscopic capillary bed. To integrate data acquired at multiple length scales with different neuroimaging modalities and to reconcile brain-wide macroscale information with microscale multiphoton data, we developed a method for synthesizing hemodynamically equivalent vascular networks for the entire cerebral circulation. This computational approach is intended to aid in the quantification of patterns of cerebral blood flow and metabolism for the entire brain. In part I, we described the mathematical framework for image-guided generation of synthetic vascular networks covering the large cerebral arteries from the circle of Willis through the pial surface network leading back to the venous sinuses. Here in part II, we introduce novel procedures for creating microcirculatory closure that mimics a realistic capillary bed. We demonstrate our capability to synthesize synthetic vascular networks whose morphometrics match empirical network graphs from three independent state-of-the-art imaging laboratories using different image acquisition and reconstruction protocols. We also successfully synthesized twelve vascular networks of a complete mouse brain hemisphere suitable for performing whole-brain blood flow simulations. Synthetic arterial and venous networks with microvascular closure allow whole-brain hemodynamic predictions. Simulations across all length scales will potentially illuminate organ-wide supply and metabolic functions that are inaccessible to models reconstructed from image data with limited spatial coverage.

Transfer of idiotypic protein primed allogeneic marrow grafts elicits potent graft-versus-myeloma effects in mice

The active immunization of bone marrow (BM) donors with myeloma immunoglobulin (Ig) results in an idiotypic T cell response that can be transferred to the recipient. Using a murine model we evaluated the effectiveness, side-effects and underlying mechanisms of this approach. Balb/c (H-2d) mice were given a dose of HOPC-1F myeloma cells secreting the monoclonal IgG2a followed by lethal total body irradiation (7.5 Gy) 2 days later and a subsequent transplantation of 2 x 10(7) allogeneic MHC-matched DBA/2-derived marrow cells. Donors were pre-immunized with three i.p. injections of HOPC(IgG2a) or control Ig given with incomplete Freund's adjuvants (IFA) spaced 1 week apart. In some experiments, donor-spleen cells were additionally transferred 2 h post transplant. Injection of HOPC-myeloma led to death of all animals after a median survival time (MST) of 42 days. A lethal dose of TBI followed by transfer of unmanipulated marrow grafts plus splenocytes resulted in moderate antimyeloma effects with 8% of mice achieving long-term survival. Nearly the same results were obtained after transplantation of BM immunized with the control Ig. In contrast, transplantation of marrow grafts from HOPC(IgG2a) immunized donors exerted a significant GVM effect with 63% long-term survival for more than 180 days. The additional transfer of 2 x 10(7) immune splenocytes derived from the same donor resulted in even stronger anti-myeloma effects (FFR 87%). No increase in the incidence of severe acute GVHD was observed. In vitro data suggest that allogeneic CD8+ idiotype-specific T cells may be the major effector cells. Our results demonstrate that active immunization of the donor with the myeloma-specific Ig can induce powerful graft-versus-myeloma effects after allogeneic BMT.

Quantification of blood flow patterns in the cerebral arterial circulation of individual (human) subjects

There is a growing research interest in quantifying blood flow distribution for the entire cerebral circulation to sharpen diagnosis and improve treatment options for cerebrovascular disease of individual patients. We present a methodology to reconstruct subject-specific cerebral blood flow patterns in accordance with physiological and fluid mechanical principles and optimally informed by in vivo neuroimage data of cerebrovascular anatomy and arterial blood flow rates. We propose an inverse problem to infer blood flow distribution across the visible portion of the arterial network that best matches subject-specific anatomy and a given set of volumetric flow measurements. The optimization technique also mitigates the effect of uncertainties by reconciling incomplete flow data and by dissipating unavoidable acquisition errors associated with medical imaging data.

Starling forces drive intracranial water exchange during normal and pathological states

AIM

To quantify the exchange of water between cerebral compartments, specifically blood, tissue, perivascular pathways, and cerebrospinal fluid-filled spaces, on the basis of experimental data and to propose a dynamic global model of water flux through the entire brain to elucidate functionally relevant fluid exchange phenomena.

METHODS

The mechanistic computer model to predict brain water shifts is discretized by cerebral compartments into nodes. Water and species flux is calculated between these nodes across a network of arcs driven by Hagen-Poiseuille flow (blood), Darcy flow (interstitial fluid transport), and Starling's Law (transmembrane fluid exchange). Compartment compliance is accounted for using a pressure-volume relationship to enforce the Monro-Kellie doctrine. This nonlinear system of differential equations is solved implicitly using MATLAB software.

RESULTS

The model predictions of intraventricular osmotic injection caused a pressure rise from 10 to 22 mmHg, followed by a taper to 14 mmHg over 100 minutes. The computational results are compared to experimental data with R2=0.929. Moreover, simulated osmotic therapy of systemic (blood) injection reduced intracranial pressure from 25 to 10 mmHg. The modeled volume and intracranial pressure changes following cerebral edema agree with experimental trends observed in animal models with R2=0.997.

CONCLUSION

The model successfully predicted time course and the efficacy of osmotic therapy for clearing cerebral edema. Furthermore, the mathematical model implicated the perivascular pathways as a possible conduit for water and solute exchange. This was a first step to quantify fluid exchange throughout the brain.