A phase I dose escalation study of BIBW 2992, an irreversible dual inhibitor of epidermal growth factor receptor 1 (EGFR) and 2 (HER2) tyrosine kinase in a 2-week on, 2-week off schedule in patients with advanced solid tumours.

To assess tolerability, pharmacokinetics (PK), pharmacodynamics (PD) and clinical activity of the dual epidermal growth factor receptor (EGFR) 1 and 2 (HER2) tyrosine kinase inhibitor BIBW 2992. An escalating schedule of once-daily (OD) BIBW 2992 for 14 days followed by 14 days off medication was explored. Thirty-eight patients were enrolled. Dose levels were 10, 20, 30, 45, 70, 85, and 100 mg. At 100 mg dose-limiting toxicity (DLT) (common toxicity criteria grade 3 skin rash and grade 3 diarrhoea despite treatment with loperamide) occurred in two patients. In the next-lower dose of 70 mg, DLT (grade 3 fatigue and ALAT elevation) occurred in one of six patients. An intermediate dose level of 85 mg was studied. Here DLT occurred in two patients (grade 3 diarrhoea despite treatment and grade 2 diarrhoea lasting more than 7 days despite treatment). An additional 12 patients were treated at 70 mg. BIBW 2992 PK after single and multiple doses revealed moderately fast absorption, and no deviation from dose proportionality. Pharmacodynamics analysis in skin biopsies did not show significant changes in EGFR-associated biomarkers. However, a significant inhibitory effect on the proliferation index of epidermal keratinocytes was observed. No partial or complete responses were observed, stable disease lasting more than four cycles was seen in seven patients. The recommended dose for studies with BIBW 2992 for 14 days followed by 14 days off medication is 70 mg OD.

Population pharmacokinetics of sibrotuzumab, a novel therapeutic monoclonal antibody, in cancer patients.

Population pharmacokinetics of sibrotuzumab, a humanized monoclonal antibody directed against fibroblast activation protein, were determined after multiple intravenous infusions of dosages ranging from 5 mg/m(2) to an absolute dose of 100 mg, in patients with advanced or metastatic carcinoma. In total, 1844 serum concentrations from 60 patients in three Phase I and II clinical studies were analyzed. The structural model incorporated two disposition compartments and two parallel elimination pathways from the central compartment, one linear and one nonlinear. Finally estimated pharmacokinetic parameters (%RSE) were: linear clearance CLL 22.1 ml/h (9.6), central distribution volume V1 4.13l (3.7), peripheral volume V2 3.19l (8.8), inter-compartmental clearance Q 37.6 ml/h (9.6); for the nonlinear clearance Vmax was 0.0338 mg/h (25) and Km 0.219 microg/ml (57). At serum concentrations between approximately 20 ng/ml and 7 microg/ml, the effect of the nonlinear clearance on pharmacokinetics was marked. Only at >7 microg/ml did CLL dominate overall clearance. Interindividual variability was 57% for CLL, 20% for V1 and V2, and 29% for Vmax and was larger than the inter-occasional variability of 13%. Of the many investigated patient covariates, only body weight was found to contribute to the population model. It significantly affected CLL, V1, V2 and Vmax resulting in marked differences in the model-predicted concentration-time profiles after multiple dosing in patients with low and high body weights. In conclusion, a robust population pharmacokinetic model was developed and evaluated for sibrotuzumab, which identified a possible need to consider body weight when designing dosage regimen for future clinical cancer trials.

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.

Phase I and pharmacokinetic study of BIBX 1382 BS, an epidermal growth factor receptor (EGFR) inhibitor, given in a continuous daily oral administration.

The pyrimido-pyrimidine BIBX 1382 BS inhibits the intracellular tyrosine kinase domain of the epidermal growth factor receptor (EGFR), thus specifically reverting the aberrant enzymatic activity from overexpressed and constitutively activated EGFR. A phase I and pharmacokinetic study of this new specific molecule was carried out. After initially performing an accelerated titration design from the first toxicities onwards, a modified Fibonacci scheme was used to escalate the daily oral dose. The following dosages and cycles (defined as treatment during 28 days) were applied: 25 mg: 6; 50 mg: 3; 100 mg: 6; 200 mg: 7; 150 mg: 3. Over a 10 months accrual phase, 11 patients (pts) (7 females, 4 males) with a median age of 63 years (range 50-73 years), World Health Organization Performance Status (WHO PS) 0:5 pts, 1:6 pts and miscellaneous solid tumours were entered. The median number of cycles applied per pt was 2 (range 1-7). Reversible, dose-dependent increase of liver enzymes (maximal Common Toxicity Criteria (CTC) grades: gamma-glutamyl transferase (GGT): 4, aspartate aminotransferase (GOT): 3, alanine aminotransferase (GPT): 3, alkaline phosphatase (AP): 3, bilirubin: 3) occurred. Oral medication yielded plasma levels far below those expected to be efficacious. In conclusion, target plasma levels could not be reached via the oral route at a reasonable dosage. Meanwhile, a preclinically unknown metabolite was identified from the urine of one patient. Subsequently, this metabolite was found to be abundant in patient plasma. The metabolite was demonstrated to be pharmacologically inactive. Due to a dose-limiting increase of liver enzymes, low bioavailability of BIBX 1382 BS and the detection of a pharmacologically inactive metabolite, this trial was discontinued.

Evidence for an anion exchange mechanism for uptake of conjugated bile acid from the rat jejunum.

Absorption of conjugated bile acids from the small intestine is very efficient. The mechanisms of jejunal absorption are not very well understood. The aim of this study was to clarify the mechanism of absorption of conjugated bile acid at the apical membrane of jejunal epithelial cells. Brush-border membrane vesicles from intestinal epithelial cells of the rat were prepared. Absorption of two taurine-conjugated bile acids that are representative of endogenous bile acids in many variate vertebrate species were studied. In ileal, but not jejunal brush-border membrane vesicles, transport of conjugated bile acids was cis-stimulated by sodium. Transport of conjugated bile acids was trans-stimulated by bicarbonate in the jejunum. Absorption of conjugated dihydroxy-bile acids was almost twice as fast as of trihydroxy-bile acids. Coincubation with other conjugated bile acids, bromosulfophthalein, and DIDS, as well as by incubation in the cold inhibited the transport rate effectively. Absorption of conjugated bile acids in the jejunum from the rat is driven by anion exchange and is most likely an antiport transport.

Successful topical dissolution of cholesterol gallbladder stones using ethyl propionate.

Topical dissolution of cholesterol gallbladder stones using methyl tert-butyl ether (MTBE) is useful in symptomatic patients judged too ill for surgery. Previous studies showed that ethyl propionate (EP), a C5 ester, dissolves cholesterol gallstones rapidly in vitro, but differs from MTBE in being eliminated so rapidly by the liver that blood levels remain undetectable. Our aim was to test EP as a topical dissolution agent for cholesterol gallbladder stones. Five high-risk patients underwent topical dissolution of gallbladder stones by EP. In three patients, the solvent was instilled via a cholecystostomy tube placed previously to treat acute cholecystitis; in two patients, a percutaneous transhepatic catheter was placed in the gallbladder electively. Gallstone dissolution was assessed by chromatography, by gravimetry, and by catheter cholecystography. Total dissolution of gallstones was obtained in four patients after 6-10 hr of lavage; in the fifth patient, partial gallstone dissolution facilitated basketing of the stones. In two patients, cholesterol dissolution was measured and averaged 30 mg/min. Side effects were limited to one episode of transient hypotension and pain at the infusion site; no patient developed somnolence or nausea. Gallstone elimination was associated with relief of symptoms. EP is an acceptable alternative to MTBE for topical dissolution of cholesterol gallbladder stones in high-risk patients. The lower volatility and rapid hepatic extraction of EP suggest that it may be preferable to MTBE in this investigational procedure.

Intestinal absorption of sodium dodecyl sulfate in the rodent: evidence for paracellular absorption.

Experiments were performed to define the mechanism of intestinal absorption of dodecyl sulfate (DS), an amphipathic organic anion whose chemical structure resembles that of dodecanoate, a C12 fatty acid anion. With jejunal segments perfused in single-pass fashion in the anesthetized rat, steady-state absorption of DS was concentration dependent, with the apparent permeability constant (P(app)) ranging from 4 to 22 x 10(-5) cm/s. When DS concentration was held constant and net water absorption was induced by decreasing perfusate osmolality, DS absorption increased in direct proportion to water absorption, suggesting absorption by solvent drag via the paracellular route. However, DS absorption continued even when water secretion was induced by a hypertonic perfusate. Consequently, for all experiments, DS absorption could be empirically described as the sum of two terms: 1) absorption in the absence of water absorption (P(app) = 5.6 x 10(-5) cm/s) and 2) absorption induced by water movement [(delta P(app)/delta water absorption) = 0.2 x 10(-5) cm x s(-1) x microl segment(-1) x min(-1)]. In a polarized epithelial monolayer of renal epithelial cells (Madin-Darby canine kidney cells), DS was absorbed predominantly by a paracellular pathway, as the absorption rate increased threefold when paracellular junction pore size was increased by the addition of cytochalasin D. The calculated apparent radius was 2.9 A, indicating that the cross section of the molecule, not its length, determined the rate of absorption. It is concluded that absorption of DS in the intact animal occurs slowly and mostly via the paracellular route, because the fixed negative charge on the molecule retards rapid passive entry into the enterocyte, as occurs with protonated fatty acids. That absorption of DS persisted despite net water secretion suggests a low level of transcellular absorption across the jejunal enterocyte also occurs.

Carrier-mediated jejunal absorption of conjugated bile acids in the guinea pig.

BACKGROUND & AIMS: Conjugated bile acid absorption is known to occur in the jejunum in mammals, but the mechanism has not been well defined. The aim of this study was to define the mechanisms by which conjugated bile acids are absorbed from the jejunum. METHODS: The steady-state absorption of eight conjugated bile acids from a perfused jejunal segment was measured in the anesthetized biliary fistula guinea pig. Experiments defined the effect of bile acid structure, tested for competitive inhibition and saturation of transport, and compared the absorption rate of taurine conjugates with that of glycine conjugates at pH 7.6 or 5.0. RESULTS: Dihydroxy conjugates were absorbed twice as rapidly as cholyl conjugates from the perfused jejunum; glycine and taurine conjugates of a given bile acid were absorbed at a similar rate. Absorption of ursodeoxycholate taurine showed saturability and competitive inhibition by other conjugated bile acids. When intraluminal pH was decreased to pH 5.0, the absorption rate of glycine (but not taurine) conjugates increased, indicating passive absorption of the protonated species of glycine-conjugated bile acids. CONCLUSIONS: Uptake of glycine- or taurine-conjugated bile acids by the guinea pig jejunum occurs by at least two mechanisms: carrier-mediated transport (dihydroxy conjugates greater than trihydroxy conjugates) and passive absorption in protonated (uncharged) form of glycine conjugates.

Cyclic adenosine-3',5'-monophosphate production is greater in rabbit duodenal crypt than in villus cells.

BACKGROUND: Duodenal surface epithelial cells secrete bicarbonate. Agonists of duodenal alkaline secretion (such as vasoactive intestinal polypeptide (VIP), prostaglandin E2 (PGE(2)), and forskolin) increase intracellular cyclic adenosine-3', 5-monophosphate (cAMP), and cAMP stimulates Cl-HCO(3)- exchange in duodenal brush border membrane vesicles. As intestinal villus and crypt cells differ in function, our aims were to contrast cAMP generation in duodenal villus versus crypt cells in response to VIP, PGE(2), and forskolin. METHODS: Villus and crypt rabbit duodenal enterocytes were isolated by calcium chelation. To prevent the degradation of cAMP in vitro, phosphodiesterase activity was inhibited. cAMP production was quantitated in response to VIP (10(-10)-10(-5)M), PGE(2) (10(-10)-10(-4)M), and forskolin (10(-8)-10(-3)M). RESULTS: In crypt cells cAMP generation was approximately 10-fold greater (P < 0.001) in response to VIP, PGE(2), and forskolin than to villus cells. The relative orders of potency (that is, D(50), VIP > PGE(2) > forskolin) and efficacy (that is, V max, forskolin > VIP and PGE(2)) were similar in villus and crypt cells. CONCLUSION: cAMP production is greater in duodenal crypt than in villus enterocytes at rest and in response to forskolin, VIP, and PGE(2), suggesting that alkaline secretion may differ along the villus-to-crypt axis.

Bile acid metabolism and biliary secretion in patients receiving orthotopic liver transplants: differing effects of cyclosporine and FK 506.

Bile acid metabolism and biliary secretion were characterized in the first 2 wk after orthotopic liver transplantation in 15 patients receiving cyclosporine and in five patients receiving FK 506. Analyses were performed on hepatic bile obtained by T-tube drainage; values obtained were compared with literature values for bile samples obtained in patients who had undergone cholecystectomy. Biliary bile acid output, which is equivalent to bile acid biosynthesis from cholesterol, was low (mean +/- S.E.M.) and increased with time: day 1, 0.50 +/- 0.1 mmol/day; day 3, 0.8 +/- 0.1 mmol/day; and day 6, 1.6 +/- 0.5 mmol/day. Chenodeoxycholic acid biosynthesis, as percent of total bile acid biosynthesis, was abnormally low in patients receiving cyclosporine (16.2 +/- 1.1) but not in patients receiving FK 506 (38.2 +/- 4.8) (p < 0.005). Before the T-tube was clamped, the proportion of deoxycholic acid (a secondary bile acid formed by bacterial 7-dehydroxylation of cholic acid) was low in both groups: cyclosporine, 0.4 +/- 0.1; FK 506, 4.8 +/- 2.5 (p < 0.01). The mean concentration of bile acids in hepatic bile between days 4 and 11 did not differ significantly between groups: cyclosporine, 7.7 +/- 1.3 mmol/L; FK 506 4.3 +/- 0.7 mmol/L (mean +/- S.E.M.). (These values are similar to those reported for patients who have undergone cholecystectomy.) Bile acid-dependent bile flow, expressed as apparent choleretic activity (microliters of bile per micromole of bile acid output), was markedly elevated: in patients receiving cyclosporine the value was 129, and in patients receiving FK 506 the value was 220. (In patients who have undergone cholecystectomy, this value is less than 30).(ABSTRACT TRUNCATED AT 250 WORDS)

Extracorporeal shock wave lithotripsy of gallstones in different biles and water in vitro.

Twenty-four gallstones were fragmented by extracorporeal shock wave lithotripsy (ESWL) to compare the influence of three different biles (bovine bile, human bile, synthetic bile) and water on the rapidity of fragmentation. Four groups of comparable stones were used for lithotripsy in vitro. The stones were collected from 6 patients, four nearly identical 'sister' stones from each patient. The number of shock waves required for adequate fragmentation (fragments < or = 4 mm) was measured for comparison. Overall highly significant differences were found for the four different 'biles' with regard to the number of shock waves required for adequate fragmentation. Using synthetic bile, which was artificially composed according to a textbook on hepatology, significantly more shock waves were necessary for fragmentation compared to the use of water, bovine bile or human bile. On the other hand, no significant difference between water and human bile could be registered. We conclude that the number of shock waves required for adequate lithotripsy is influenced by the composition of bile in which the stone is fragmented. Possibly results of ESWL can be improved by manipulation of the bile.

Influence of heparin treatment on biochemical markers of an activation of the coagulation system.

Monitoring of anticoagulant treatment is not yet satisfactory. Otherwise optimal treatment control in special situations as low dose heparin prophylaxis in hip surgery or high dose anticoagulant treatment in patients after coronary stent implantation may be desirable. Recently available thrombin markers were analyzed in 51 patients under low dose (group 1) and 30 patients under high dose therapy with unfractionated heparin (group 2a and b) as well as in controls (n = 26). Before therapy these parameters were significantly elevated in both patient groups. Elevated thrombin-antithrombin III-complexes (TAT) despite adequate prolongation of aPTT under high dose heparin in 38.2% of patients indicate that therapeutic concentrations of heparin in these cases are insufficient for depressing this parameter completely. During low dose therapy only prothrombin fragment (F1 + 2) significantly decreased. This may be explained by catalytic induction of TAT-complex formation by heparin. Decrease of D-Dimer under heparin therapy in both groups does not parallel with TAT and F1 + 2 but was more prolonged. This can be explained by dependence of the D-Dimer level on spontaneous fibrinolytic activity and by a longer plasma half-life as well as a chronic and continuous fibrinolytic process in an older thrombus. In conclusion, thrombin markers seem to be helpful in estimating anticoagulant treatment efficacy. As a consequence, anticoagulant treatment has to be intensified in high-risk patients for complete depression of these markers. Whether the benefit of higher heparin doses is worth the risk of drug-induced hemorrhage, however, remains to be clarified in clinical studies.