Pharmacokinetic-Interactions of BI 425809, a Novel Glycine Transporter 1 Inhibitor, With Cytochrome P450 and P-Glycoprotein Substrates: Findings From In Vitro Analyses and an Open-Label, Single-Sequence Phase I Study

PURPOSE/BACKGROUND

Glycine transporter-1 inhibitors may ameliorate cognitive deficits in schizophrenia. This study evaluated potential drug-drug interactions with the glycine transporter-1 inhibitor BI 425809.

METHODS/PROCEDURES

Interactions with cytochromes P450 (CYP) and P-glycoprotein (P-gp) were assessed in in vitro assays using human hepatocytes and Caco-2 cells, respectively. Pharmacokinetic characteristics of probe drugs were subsequently assessed in a Phase I, open-label, single-sequence crossover study in healthy male participants. Participants received a probe-drug cocktail containing midazolam (CYP3A4), warfarin (CYP2C9), and omeprazole (CYP2C19) and a separate dose of digoxin (P-gp), alone and on a background of steady-state BI 425809 25 mg once daily in 2 treatment periods. Adverse events were monitored.

FINDINGS/RESULTS

In vitro assays revealed concentration-dependent induction of CYP3A4 and inhibition of P-gp by BI 425809. In the clinical study, 12 of 13 participants completed both periods. With BI 425809, area under the plasma concentration curve from administration to the last measurement (AUC 0-tz ) and maximum plasma concentration ( Cmax ) for midazolam were lower than when administered alone. Adjusted geometric mean ratios (90% confidence interval) were 70.6% (63.9%-78.1%) for AUC 0-tz and 77.6% (67.3%-89.4%) for Cmax . For warfarin and digoxin, AUC 0-tz and Cmax were similar with and without BI 425809. For omeprazole, BI 425809 slightly reduced AUC 0-tz but not Cmax versus omeprazole alone. No new safety signals were identified.

IMPLICATIONS/CONCLUSIONS

These findings indicate induction of CYP3A4 by once-daily BI 425809 25 mg (the assumed highest therapeutic dose) and no meaningful effects on CYP2C9, CYP2C19, or P-gp in vivo.

Effects of Cytochrome P450 3A4 Induction and Inhibition on the Pharmacokinetics of BI 425809, a Novel Glycine Transporter 1 Inhibitor

Background and Objective

Increased glycine availability at the synaptic cleft may enhance N-methyl-D-aspartate receptor signalling and provide a promising therapeutic strategy for cognitive impairment associated with schizophrenia. These studies aimed to assess the pharmacokinetics of BI 425809, a potent glycine-transporter-1 inhibitor, when co-administered with a strong cytochrome P450 3A4 (CYP3A4) inhibitor (itraconazole) and inducer (rifampicin).

Methods

In vitro studies using recombinant CYPs, human liver microsomes, and human hepatocytes were conducted to determine the CYP isoforms responsible for BI 425809 metabolism. In addition, two open-label, fixed-treatment period, phase I studies in healthy male volunteers are described. Period 1: participants received oral BI 425809 25 mg (single dose) on day 1; period 2: participants received multiple doses, across 10 days, of oral itraconazole or rifampicin combined with a single dose of oral BI 425809 25 mg on day 4/7 of the itraconazole/rifampicin treatment, respectively. Pharmacokinetic and safety endpoints were assessed in the absence/presence of itraconazole/rifampicin and included area under the concentration-time curve (AUC) over the time interval 0–167 h (AUC_0‒167; itraconazole), 0–168 h (AUC_0‒168; rifampicin), or 0–infinity (AUC_0-∞; rifampicin and itraconazole), maximum measured concentration (C_max) of BI 425809, and adverse events.

Results

In vitro results suggested that CYP3A4 accounted for ≥ 90% of the metabolism of BI 425809. BI 425809 exposure (adjusted geometric mean ratio [%]) was higher in the presence of itraconazole (AUC_0‒167: 265.3; AUC_0−∞: 597.0; C_max: 116.1) and lower in the presence of rifampicin (AUC_0‒168: 10.3; AUC_0−∞: 9.8; C_max: 37.4) compared with BI 425809 alone. Investigational treatments were well tolerated.

Conclusions

Systemic exposure of BI 425809 was altered in the presence of strong CYP3A4 modulators, corroborating in vitro results that CYP3A4 mediates a major metabolic pathway for BI 425809.

Trial Registration Number

NCT02342717 (registered on 15 January 2015) and NCT03082183 (registered on 10 March 2017)

Supplementary Information

The online version contains supplementary material available at 10.1007/s13318-021-00723-y.

Clinical Pharmacokinetics and Pharmacodynamics of Nintedanib

Nintedanib is an oral, small-molecule tyrosine kinase inhibitor approved for the treatment of idiopathic pulmonary fibrosis and patients with advanced non-small cell cancer of adenocarcinoma tumour histology. Nintedanib competitively binds to the kinase domains of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF). Studies in healthy volunteers and in patients with advanced cancer have shown that nintedanib has time-independent pharmacokinetic characteristics. Maximum plasma concentrations of nintedanib are reached approximately 2–4 h after oral administration and thereafter decline at least bi-exponentially. Over the investigated dose range of 50–450 mg once daily and 150–300 mg twice daily, nintedanib exposure increases are dose proportional. Nintedanib is metabolised via hydrolytic ester cleavage, resulting in the formation of the free acid moiety that is subsequently glucuronidated and excreted in the faeces. Less than 1% of drug-related radioactivity is eliminated in urine. The terminal elimination half-life of nintedanib is about 10–15 h. Accumulation after repeated twice-daily dosing is negligible. Sex and renal function have no influence on nintedanib pharmacokinetics, while effects of ethnicity, low body weight, older age and smoking are within the inter-patient variability range of nintedanib exposure and no dose adjustments are required. Administration of nintedanib in patients with moderate or severe hepatic impairment is not recommended, and patients with mild hepatic impairment should be monitored closely and the dose adjusted accordingly. Nintedanib has a low potential for drug–drug interactions, especially with drugs metabolised by cytochrome P450 enzymes. Concomitant treatment with potent inhibitors or inducers of the P-glycoprotein transporter can affect the pharmacokinetics of nintedanib. At an investigated dose of 200 mg twice daily, nintedanib does not have proarrhythmic potential.

No relevant pharmacokinetic drug-drug interaction between nintedanib and pirfenidone

Nintedanib and pirfenidone are approved treatments for idiopathic pulmonary fibrosis (IPF). This open-label, two-group trial investigated the pharmacokinetic drug-drug interaction between these two drugs in patients with IPF.Subjects not treated with antifibrotics at screening (group 1, n=20) received a single nintedanib dose (150 mg) followed by pirfenidone (titrated to 801 mg thrice daily) for 3 weeks, with a further single nintedanib dose (150 mg) on the last day (day 23). Subjects treated with pirfenidone at screening (group 2, n=17) continued to receive pirfenidone alone (801 mg thrice daily) for 7 days, then co-administered with nintedanib (150 mg twice daily) for a further 7 days, before single doses of both treatments on day 16.In group 1, adjusted geometric mean (gMean) ratios (with/without pirfenidone) were 88.6% and 80.6% for nintedanib area under the plasma concentration-time curve (AUC) and maximum plasma concentration (C_max), respectively. In group 2, gMean ratios (with/without nintedanib) were 97.2% and 99.5% for pirfenidone AUC and C_max, respectively. For all parameters, the 90% confidence intervals included 100%, suggesting similar exposure for administration alone and when co-administered. Both treatments were well tolerated.These data indicate there is no relevant pharmacokinetic drug-drug interaction between nintedanib and pirfenidone when co-administered in IPF patients.

Multiple Rising Doses of Oral BI 425809, a GlyT1 Inhibitor, in Young and Elderly Healthy Volunteers: A Randomised, Double-Blind, Phase I Study Investigating Safety and Pharmacokinetics

Background and Objective

Schizophrenia and Alzheimer’s disease are characterised by abnormalities in glutamatergic pathways related to N-methyl-d-aspartate receptor hypofunction. Glycine is an N-methyl-d-aspartate receptor co-agonist; inhibition of glycine transporter 1 may improve N-methyl-d-aspartate receptor function. This phase I, randomised, two-part study evaluated the safety, tolerability and pharmacokinetic profile of BI 425809, a novel glycine transporter 1 inhibitor, in healthy male and female volunteers.

Methods

Part 1 evaluated BI 425809 10, 25, 50 or 75 mg once daily or 75 mg twice daily in young subjects, and 25 mg or 50 mg once daily in elderly subjects. Each dose group comprised 12 subjects who received BI 425809 (n = 9) or placebo (n = 3) for 14 days (day 1: single dose; days 4–14: multiple dosing). Part 2 compared pharmacokinetic profiles in 12 subjects who received a single dose of BI 425809 25 mg in the morning and evening.

Results

Pharmacokinetic profiles were similarly shaped for all dose groups. Median time to maximum plasma concentration was 3.0–4.5 h with steady state being reached between days 6 and 10. Pharmacokinetic parameters demonstrated dose linearity at the predicted therapeutic exposure range of BI 425809 ≤ 25 mg once daily, but increased less than dose proportionally for ≥ 50 mg once daily. All reported adverse events were of mild-to-moderate intensity, 51/84 (61%; part 1) subjects had one or more treatment-related adverse event, no serious adverse events occurred and no dose dependency was observed.

Conclusions

Pharmacokinetic properties support both morning and evening dosing. BI 425809 was generally well tolerated at all tested doses.

Clinicaltrials.gov identifier

NCT02337283.

Electronic supplementary material

The online version of this article (10.1007/s40261-018-0660-2) contains supplementary material, which is available to authorized users.

Safety, Tolerability and Pharmacokinetics of Oral BI 425809, a Glycine Transporter 1 Inhibitor, in Healthy Male Volunteers: A Partially Randomised, Single-Blind, Placebo-Controlled, First-in-Human Study

BACKGROUND AND OBJECTIVES

Schizophrenia and Alzheimer's disease are characterised by glutamatergic pathway abnormalities related to N-methyl-D-aspartate (NMDA) receptor hypofunction and cognitive impairment. Glycine is an NMDA receptor co-agonist; inhibition of glycine transporter 1 (GlyT1) should improve NMDA receptor hypofunction. This study evaluated safety and pharmacokinetic properties of BI 425809-a potent and selective GlyT1 inhibitor.

METHODS

In the single-rising dose (SRD) component of this study, subjects were randomised to a single dose of BI 425809 [doses (mg): 0.5, 1, 2, 5, 10, 25, 50, 100 and 150], or placebo. The bioavailability/food effect (BA/FE) component investigated BI 425809 pharmacokinetics following single dosing (25-mg tablet) after overnight fasting or with a high-calorie meal or as solution (25 mg) after overnight fasting.

RESULTS

Overall, 33/83 (39.8%) subjects had ≥ 1 treatment-related adverse event (AE); there were no deaths or serious AEs. Reported SRD part AEs trended towards dose dependency, occurring at the higher doses (mostly central nervous system related). BI 425809 plasma concentration-time profiles were similarly shaped across all doses and plasma exposure increased proportional to dose. In the BA/FE component, geometric mean ratios for the area under the concentration-time curve from time zero to the last measurable concentration and the maximum plasma concentration for tablet fasted versus solution fasted were 80.5 and 50.0%, respectively, and for tablet fed versus fasted were 125.9 and 142.1%, respectively.

CONCLUSION

BI 425809 was generally well-tolerated at doses expected to be clinically relevant. The AE profile suggested possible GlyT1-inhibiting effects.

CLINICAL TRIAL IDENTIFIER

NCT02068690.

Evaluation of Pharmacokinetics and Pharmacodynamics of BI 425809, a Novel GlyT1 Inhibitor: Translational Studies

BI 425809 is a potent and selective glycine transporter 1 (GlyT1) inhibitor being developed for the treatment of cognitive impairment in Alzheimer disease and schizophrenia. Translational studies evaluated the effects of BI 425809 on glycine levels in rat and human cerebrospinal fluid (CSF). Oral administration of BI 425809 in rats induced a dose‐dependent increase of glycine CSF levels from 30% (0.2 mg/kg, not significant) to 78% (2 mg/kg, P < 0.01), relative to vehicle. Similarly, oral administration of BI 425809 in healthy volunteers resulted in a dose‐dependent increase in glycine CSF levels at steady state, with a mean 50% increase at doses as low as 10 mg. The peak plasma concentration (C_max) of BI 425809 was achieved earlier in plasma than in CSF (t_max 3–5 vs. 5–8 hours, respectively). Generally, BI 425809 was safe and well tolerated. These data provide evidence of functional target engagement of GlyT1 by BI 425809.

A Phase I dose-escalation study of afatinib combined with nintedanib in patients with advanced solid tumors

AIMS

To evaluate the safety and maximum tolerated dose (MTD) of afatinib combined with nintedanib.

MATERIALS & METHODS

Patients received afatinib 10-20 mg daily plus nintedanib 150-200 mg twice daily (28-day cycle). Dose escalation followed a 3+3 design.

RESULTS

Patients received afatinib/nintedanib: 10/150 mg (n = 11); 10/200 mg (n = 13; MTD); 20/200 mg (n = 4). Four patients had dose-limiting toxicities (all grade 3): increased alanine aminotransferase (afatinib/nintedanib: 10/150 mg), diarrhea (10/200 mg), dehydration (20/200 mg), diarrhea with elevated liver enzymes (20/200 mg). Frequent treatment-related adverse events were diarrhea, nausea, anorexia, fatigue and vomiting. In total, 14 patients (46.2%) had objective responses at the MTD.

CONCLUSION

The MTD, afatinib 10 mg daily plus nintedanib 200 mg twice daily, had a manageable safety profile, but was considered subtherapeutic for Phase II evaluation.

A phase II study of afatinib, an irreversible ErbB family blocker, added to letrozole in patients with estrogen receptor-positive hormone-refractory metastatic breast cancer progressing on letrozole

Phase II, open-label study assessing the efficacy and safety of the ErbB family blocker afatinib combined with letrozole in estrogen receptor-positive metastatic breast cancer (MBC) patients who had progressed on letrozole monotherapy. Adult females (N = 28) received oral afatinib (50 [n = 7], 40 [n = 13] or 30 [n = 8] mg/day) plus letrozole 2.5 mg/day in 28-day cycles until disease progression. Primary endpoint was the progression-free rate at or after 16 weeks of afatinib. At 16 weeks, four patients remained on afatinib without progression; two of these were HER2 negative. Fifteen (54 %) patients had a best response of stable disease according to Response Evaluation Criteria in Solid Tumors. Median progression-free survival was 60, 107 and 79 days with 50, 40 and 30 mg/day afatinib, respectively. Diarrhea, asthenia, rash, mucosal inflammation and nausea were the most frequent adverse events. In this small, exploratory study, afatinib combined with letrozole was able to induce disease stabilization in 54 % of hormone-refractory MBC patients previously progressing on letrozole.

Clinical trial registration: NCT00708214

Pharmacokinetic drug interactions of afatinib with rifampicin and ritonavir

BACKGROUND AND OBJECTIVE

Afatinib is a potent, irreversible, ErbB family blocker in clinical development for the treatment of advanced non-small cell lung cancer, metastatic head and neck cancer, and other solid tumours. As afatinib is a substrate for the P-glycoprotein (P-gp) pump transporter the three studies presented here investigated the pharmacokinetics of afatinib in the presence of a potent inhibitor (ritonavir) or inducer [rifampicin (rifampin)] of P-gp.

METHODS

We conducted phase I, open-label, single-centre studies in healthy male volunteers who received a single once-daily oral dose of afatinib (20 or 40 mg) together with either ritonavir or rifampicin; two studies had a randomised, two- and three-way crossover design and the third was a non-randomised, two-period sequential study.

RESULTS

When afatinib 20 mg was administered 1 h after ritonavir, afatinib geometric mean (gMean) maximum plasma concentration (C max) and area under the plasma concentration-time curve from time zero to infinity (AUC∞) increased by 38.5 and 47.6 %, respectively. Coadministration of ritonavir either simultaneously or 6 h later than afatinib 40 mg resulted in minimal increase in the afatinib gMean C max and AUC∞ (4.1 and 18.6 % for simultaneous administration with AUC∞ not completely within the bioequivalence limits; 5.1 and 10.8 % for timed administration within the bioequivalence limits). Administration of afatinib 40 mg in the presence of rifampicin led to reduction in C max and AUC∞ by 21.6 and 33.8 %, respectively. In all studies, P-gp modulation mainly affected the extent of absorption of afatinib; there was no change in the terminal elimination half-life. The overall safety profile of afatinib was acceptable.

CONCLUSION

Coadministration of potent P-gp modulators had no clinically relevant effect on afatinib exposure. Effects of potent P-gp inhibitors were minimal at higher afatinib doses and can be readily managed by the timing of concomitant therapy. As afatinib is not a relevant modulator or substrate of cytochrome P450 enzymes, the drug-drug interaction potential is considered to be low.

Phase I/randomized phase II study of afatinib, an irreversible ErbB family blocker, with or without protracted temozolomide in adults with recurrent glioblastoma

BACKGROUND

This phase I/II trial evaluated the maximum tolerated dose (MTD) and pharmacokinetics of afatinib plus temozolomide as well as the efficacy and safety of afatinib as monotherapy (A) or with temozolomide (AT) vs temozolomide monotherapy (T) in patients with recurrent glioblastoma (GBM).

METHODS

Phase I followed a traditional 3 + 3 dose-escalation design to determine MTD. Treatment cohorts were: afatinib 20, 40, and 50 mg/day (plus temozolomide 75 mg/m(2)/day for 21 days per 28-day cycle). In phase II, participants were randomized (stratified by age and KPS) to receive A, T or AT; A was dosed at 40 mg/day and T at 75 mg/m(2) for 21 of 28 days. Primary endpoint was progression-free survival rate at 6 months (PFS-6). Participants were treated until intolerable adverse events (AEs) or disease progression.

RESULTS

Recommended phase II dose was 40 mg/day (A) + T based on safety data from phase I (n = 32). Most frequent AEs in phase II (n = 119) were diarrhea (71% [A], 82% [AT]) and rash (71% [A] and 69% [AT]). Afatinib and temozolomide pharmacokinetics were unaffected by coadministration. Independently assessed PFS-6 rate was 3% (A), 10% (AT), and 23% (T). Median PFS was longer in afatinib-treated participants with epidermal growth factor receptor (EFGR) vIII-positive tumors versus EGFRvIII-negative tumors. Best overall response included partial response in 1 (A), 2 (AT), and 4 (T) participants and stable disease in 14 (A), 14 (AT), and 21 (T) participants.

CONCLUSIONS

Afatinib has a manageable safety profile but limited single-agent activity in unselected recurrent GBM patients.

A phase Ib, open-label study to assess the safety of continuous oral treatment with afatinib in combination with two chemotherapy regimens: cisplatin plus paclitaxel and cisplatin plus 5-fluorouracil, in patients with advanced solid tumors

BACKGROUND

In this phase Ib, dose-escalation study, the oral irreversible ErbB family blocker afatinib (BIBW 2992) was combined with cisplatin (Cadila Healthcare Ltd, Ahmedabad, India) 50 or 75 mg/m(2)/paclitaxel (Bristol-Myers Squibb Pharmaceuticals Ltd, New York, USA) (Taxol)175 mg/m(2) (regimen A) or cisplatin 75-100 mg/m(2)/5-fluorouracil 750-1000 mg/m(2) (regimen B) in patients with advanced solid tumors.

PATIENTS AND METHODS

The primary objective was to assess dose-limiting toxicities (DLTs) during cycle 1 for each regimen, from which the maximum tolerated dose (MTD) was determined. Patients received once daily oral afatinib 20, 30, 40 or 50 mg in 21-day cycles (3 + 3 design).

RESULTS

The MTD for afatinib in regimens A (n = 26) and B (n = 21) was determined as 20 mg and 30 mg following DLTs in five and four patients in cycle 1, respectively. Most frequent adverse events (AEs, any grade) were diarrhea and nausea. Disease control was observed in 54% and 29% of patients in regimens A and B, respectively. Plasma sampling suggested no relevant pharmacokinetic interaction between afatinib and the chemotherapeutic agents.

CONCLUSIONS

The MTD of afatinib was 20 mg with cisplatin-paclitaxel and 30 mg with cisplatin-5-fluorouracil. Pre-emptive management of side-effects is important to maintain adequate safety and tolerability. Both combinations showed antitumor activity across tumor types and lines of prior treatment.

A phase I, open-label dose-escalation study of continuous treatment with BIBF 1120 in combination with paclitaxel and carboplatin as first-line treatment in patients with advanced non-small-cell lung cancer

BACKGROUND

BIBF 1120 is an oral potent inhibitor of vascular endothelial growth factor receptor, fibroblast growth factor receptor and platelet-derived growth factor receptor, the three key receptor families involved in angiogenesis. This phase I, open-label dose-escalation study investigated BIBF 1120 combined with paclitaxel (Taxol) and carboplatin in first-line patients with advanced (IIIB/IV) non-small-cell lung cancer.

PATIENTS AND METHODS

Patients received BIBF 1120 (starting dose 50 mg b.i.d.) on days 2-21 and paclitaxel (200 mg/m2) and carboplatin [area under curve (AUC)=6 mg/ml/min] on day 1 of each 21-day cycle. Primary end points were safety and BIBF 1120 maximum tolerated dose (MTD) in this combination. Pharmacokinetics (PK) profiles were evaluated.

RESULTS

Twenty-six patients were treated (BIBF 1120 50-250 mg b.i.d.). BIBF 1120 MTD was 200 mg b.i.d. in combination with paclitaxel and carboplatin. Six dose-limiting toxicity events occurred during treatment cycle 1 (liver enzyme elevations, thrombocytopenia, abdominal pain, and rash). Best responses included 7 confirmed partial responses (26.9%); 10 patients had stable disease. BIBF 1120 200 mg b.i.d. had no clinically relevant influence on the PK of paclitaxel 200 mg/m2 and carboplatin AUC 6 mg/ml/min and vice versa.

CONCLUSIONS

BIBF 1120 MTD was 200 mg b.i.d when given with paclitaxel and carboplatin; this combination demonstrated an acceptable safety profile. No relevant changes in PK parameters of the backbone chemotherapeutic agents or BIBF 1120 were observed.

A phase II trial to assess efficacy and safety of afatinib in extensively pretreated patients with HER2-negative metastatic breast cancer

Afatinib (BIBW 2992) is an ErbB-family blocker that irreversibly inhibits signaling from all relevant ErbB-family dimers. Afatinib has demonstrated preclinical activity in human epidermal growth factor receptor HER2 (ErbB2)-positive and triple-negative xenograft models of breast cancer, and clinical activity in phase I studies. This was a multicenter phase II study enrolling patients with HER2-negative metastatic breast cancer progressing following no more than three lines of chemotherapy. No prior epidermal growth factor receptor-targeted therapy was allowed. Patients received 50-mg afatinib once daily until disease progression. Tumor assessment was performed at every other 28-day treatment course. The primary endpoint was clinical benefit (CB) for ≥4 treatment courses in triple-negative (Cohort A) metastatic breast cancer (TNBC) and objective responses measured by Response Evaluation Criteria in Solid Tumors in patients with HER2-negative, estrogen receptor-positive, and/or progesterone receptor-positive breast cancer (Cohort B). Fifty patients received treatment, including 29 patients in Cohort A and 21 patients in Cohort B. No objective responses were observed in either cohort. Median progression-free survival was 7.4 and 7.7 weeks in Cohorts A and B, respectively. Three patients with TNBC had stable disease for ≥4 treatment courses, one of them for 12 courses (median 26.3 weeks; range 18.9–47.9 weeks). The most frequently observed afatinib-associated adverse events (AEs) were gastrointestinal and skin-related side effects, which were manageable by symptomatic treatment and dose reductions. Afatinib pharmacokinetics were comparable to those observed in previously reported phase I trials. In conclusion, afatinib had limited activity in HER2-negative breast cancer. AEs were generally manageable and mainly affected the skin and the gastrointestinal tract.

A phase II study of afatinib (BIBW 2992), an irreversible ErbB family blocker, in patients with HER2-positive metastatic breast cancer progressing after trastuzumab

Afatinib is an oral, ErbB family blocker, which covalently binds and irreversibly blocks all kinase-competent ErbB family members. This phase II, open-label, single-arm study explored afatinib activity in human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients progressing after trastuzumab treatment. Patients had stage IIIB/IV HER2-positive metastatic breast cancer, with progression following trastuzumab or trastuzumab intolerance and an Eastern Cooperative Oncology Group (ECOG) performance status of 0–2. Patients received 50 mg afatinib once-daily until disease progression. Primary endpoint was objective response rate (Response Evaluation Criteria in Solid Tumors 1.0), with tumor assessments every 8 weeks. Forty-one patients were treated. Patients had received a median of three prior chemotherapy lines (range, 0–15) and 68.3% had received trastuzumab for >1 year. Four patients (10% of 41 treated; 11% of evaluable patients) had partial response. Fifteen patients (37% of 41) had stable disease as best response and 19 (46% of 41) achieved clinical benefit. Median progression-free survival was 15.1 weeks (95% confidence interval [CI]: 8.1–16.7); median overall survival was 61.0 weeks (95% CI: 56.7–not evaluable). Most frequent common terminology criteria for adverse events grade 3 treatment-related adverse events were diarrhea (24.4%) and rash (9.8%). Afatinib monotherapy was associated with promising clinical activity in extensively pretreated HER2-positive breast cancer patients who had progressed following trastuzumab treatment.

Comparative pharmacology of chemically distinct NADPH oxidase inhibitors

BACKGROUND AND PURPOSE

Oxidative stress [i.e. increased levels of reactive oxygen species (ROS)] has been suggested as a pathomechanism of different diseases, although the disease-relevant sources of ROS remain to be identified. One of these sources may be NADPH oxidases. However, due to increasing concerns about the specificity of the compounds commonly used as NADPH oxidase inhibitors, data obtained with these compounds may have to be re-interpreted.

EXPERIMENTAL APPROACH

We compared the pharmacological profiles of the commonly used NADPH oxidase inhibitors, diphenylene iodonium (DPI), apocynin and 4-(2-amino-ethyl)-benzolsulphonyl-fluoride (AEBSF), as well as the novel triazolo pyrimidine VAS3947. We used several assays for detecting cellular and tissue ROS, as none of them is specific and artefact free.

KEY RESULTS

DPI abolished NADPH oxidase-mediated ROS formation, but also inhibited other flavo-enzymes such as NO synthase (NOS) and xanthine oxidase (XOD). Apocynin interfered with ROS detection and varied considerably in efficacy and potency, as did AEBSF. Conversely, the novel NADPH oxidase inhibitor, VAS3947, consistently inhibited NADPH oxidase activity in low micromolar concentrations, and interfered neither with ROS detection nor with XOD or eNOS activities. VAS3947 attenuated ROS formation in aortas of spontaneously hypertensive rats (SHRs), where NOS or XOD inhibitors were without effect.

CONCLUSIONS AND IMPLICATIONS

Our data suggest that triazolo pyrimidines such as VAS3947 are specific NADPH oxidase inhibitors, while DPI and apocynin can no longer be recommended. Based on the effects of VAS3947, NADPH oxidases appear to be a major source of ROS in aortas of SHRs.

A phase I study of daily BIBW 2992, an irreversible EGFR/HER-2 dual kinase inhibitor, in combination with weekly paclitaxel

e14541

Background: BIBW 2992 is an oral, potent and irreversible inhibitor of both EGFR and HER2 receptor tyrosine kinases. The efficacy of cytotoxic agents can be enhanced by erbB inhibition. The primary objective of this Phase I open- label dose-escalation trial was to determine the maximum tolerated dose (MTD) of BIBW 2992 in combination with weekly paclitaxel. Methods: This study evaluated safety, pharmacokinetics (PK), and anti-tumor efficacy of daily BIBW 2992 combined with paclitaxel administered on Days 1, 8 and 15 of a 4-weekly cycle. The dose of paclitaxel was 80 mg/m2, and the BIBW 2992 starting dose was 20 mg, escalated in successive cohorts to 40 then 50 mg. After 6 cycles of combination therapy, patients benefiting and tolerating treatment were eligible to continue single agent BIBW 2992. Results: Sixteen patients with advanced solid tumors expressing erbB receptors and suitable for treatment with a taxane have been enrolled (6 male/10 female; median age: 59 [range: 39–72]; ECOG PS 0/1: 5/11). Two dose-limiting toxicities of fatigue and mucositis occurred at a BIBW 2992 dose of 50 mg. The most frequent adverse events were fatigue, rash, mucositis and diarrhea. Partial responses were seen in patients with non-small cell lung cancer (3), prostate cancer (1), oesophageal cancer (1) and cholangiocarcinoma (1). Eight patients have remained on treatment beyond 4 cycles. The PK data of paclitaxel (with and without BIBW 2992 administration) as well as of BIBW 2992 at steady state (in combination with paclitaxel) will be described. Conclusions: A BIBW 2992 dose of 40 mg daily in combination with weekly paclitaxel 80 mg/m2 is the likely recommended dose for Phase II study. Promising anti-tumor activity was seen with this combination. The addition of bevacizumab to BIBW 2992 with 80 mg/m2 weekly paclitaxel is now being evaluated. Adverse events of BIBW 2992 combined with paclitaxel were generally mild to moderate and manageable.

[Table: see text]

Apocynin is not an inhibitor of vascular NADPH oxidases but an antioxidant

A large body of literature suggest that vascular reduced nicotinamide-adenine dinucleotide phosphate (NADPH) oxidases are important sources of reactive oxygen species. Many studies, however, relied on data obtained with the inhibitor apocynin (4'-hydroxy-3'methoxyacetophenone). Because the mode of action of apocynin, however, is elusive, we determined its mechanism of inhibition on vascular NADPH oxidases. In HEK293 cells overexpressing NADPH oxidase isoforms (Nox1, Nox2, or Nox4), apocynin failed to inhibit superoxide anion generation detected by lucigenin chemiluminescence. In contrast, apocynin interfered with the detection of reactive oxygen species in assay systems selective for hydrogen peroxide or hydroxyl radicals. Importantly, apocynin interfered directly with the detection of peroxides but not superoxide, if generated by xanthine/xanthine oxidase or nonenzymatic systems. In leukocytes, apocynin is a prodrug that is activated by myeloperoxidase, a process that results in the formation of apocynin dimers. Endothelial cells and smooth muscle cells failed to form these dimers and, therefore, are not able to activate apocynin. Dimer formation was, however, observed in Nox-overexpressing HEK293 cells when myeloperoxidase was supplemented. As a consequence, apocynin should only inhibit NADPH oxidase in leukocytes, whereas in vascular cells, the compound could act as an antioxidant. Indeed, in vascular smooth muscle cells, the activation of the redox-sensitive kinases p38-mitogen-activate protein kinase, Akt, and extracellular signal-regulated kinase 1/2 by hydrogen peroxide and by the intracellular radical generator menadione was prevented in the presence of apocynin. These observations indicate that apocynin predominantly acts as an antioxidant in endothelial cells and vascular smooth muscle cells and should not be used as an NADPH oxidase inhibitor in vascular systems.

Field-modulated carrier transport in carbon nanotube transistors

We have investigated the electrical transport properties of carbon nanotube field-effect transistors as a function of channel length, gate dielectric film thickness, and dielectric material. Our experiments show that the bulk properties of the semiconducting carbon nanotubes do not limit the current flow through the metal/nanotube/metal system. Instead, our results can be understood in the framework of gate and source-drain field induced modulation of the nanotube band structure at the source contact. The existence of one-dimensional Schottky barriers at the metal/nanotube interface determines the device performance and results in an unexpected scaling behavior.

What is the paradigm: hospital or home health care for pressure ulcers?

A home health care (HHC) referral should link the patient in a cost-effective fashion to the physician, home care, and instructions regarding ulcer management. Twenty-one patients (mean age, 74.6 years) had stage III pressure ulcers (<100 cm2) and an involved family member at home. Risk and contributing factors included cardiac disease (n = 9), hypertension (n = 14), end-stage renal disease (n = 7), smoking (n = 11), diabetes (n = 8), chronic brain syndrome (n = 14), cerebrovascular accident (n = 5), and above-the-knee amputation (n = 2). Treatment regimens included standard wound care, pressure relief and, where appropriate, culture-specific antibiotics, as well as a rehabilitation program. Home care progressively decreased the frequency of the nurse HHC and physician office visits. Resolution of the pressure ulcer varied from 6 to 32 weeks. Only two patients had progression of their wound and required hospital readmission. The billable fees included: 1) an office visit, $30.00 (medicare reimbursement, $14.00); 2) the HHC nurse visit, $159.00 (medicare reimbursement, $105.00); 3) supplies, $75.00 to $150.00/week (variable reimbursement); 4) hospitalization, $400.00 to $900.00/day; and 5) a chronic-care bed, $400.00 to $750.00/day. HHC, given a responsible support team and an involved family member, was more socially and financially acceptable than an inpatient facility. Intermittent physician visits with HHC proved safe and reliable, with 90 per cent successfully healing their wounds.

Sequential biannual prevalence studies of pressure ulcers at Allegheny-Hahnemann University Hospital

To assess the prevalence, documentation and care of pressure ulcers, and the effect of teaching and prevention strategies in a 750-bed university hospital, one-day studies were conducted in 1993, 1995, and 1997. Data gathered was used to evaluate areas in need of improvement and find cost-effective ways to reduce the prevalence of pressure ulcers. The overall prevalence of ulcers decreased from 18 percent in 1993 to 10 percent in 1995 and 1997. The prevalence of nosocomial ulcers decreased from 14 percent in 1993 to 8 percent in 1995 and 6 percent in 1997. The number of nutritional consults increased from 54 percent in 1993 to 67 percent in 1997, and more than half of all patients tested had serum albumin levels < 3.5 mg/dL. Skin assessments upon admission were completed in the majority of patients. While ulcer documentation was less than adequate for the majority of patients in 1993 and 1997, care measures, e.g., placement of patients on specialty beds or mattresses and use of dressings that provide a moist environment, improved considerably. The results of this study indicate that system-wide educational efforts aimed at all levels of patient care providers, and multi-specialty prevention and care efforts can reduce the prevalence of pressure ulcers.

Pressure ulcers: collaboration in wound care. Is there a reasonable approach?

Pressure ulcers represent a significant impact on utilization of healthcare beds, cost for the insurer, and adverse emotional impact for the family. With this in mind, one must address in an effective fashion a method of objective assessment using the current methodology to deal with risk factors in mobility, disease states, and nutrition, as well as give significant attention to prevention protocols. One should adhere to a schedule of turning the patient, sleep surfaces, and appropriate skin care while recognizing the impact of each. Finally, treatment modalities should be undertaken, not only with cost-effective issues in mind, but with ease and convenience for the healthcare provider and the least discomfort for the patient as well. One can focus on debridement by way of enzymatic, autolytic, or surgical methods, recognizing surgery as the least effective for our goals in the management of this patient. Assessment and, finally, reassessment using the available scales will allow us to provide effective healthcare in a therapeutic fashion.

Moist wound healing

The optimum wound environment to enhance wound healing is a balance of nutrition, hypoxia, and removal of debris in an occlusive moist environment. With increasing knowledge of the healing process and the variety of dressings available, the end result of any wound management will be an expedited wound healing with maximum patient comfort.

Neuropathic wounds

Neuropathic wounds commonly seen in the diabetic patient are particularly challenging diagnostic and management entities. An overview of this disorder along with clinical manifestations and treatment options are discussed.