Drug Permeability - Best Practices for Biopharmaceutics Classification System (BCS)-Based Biowaivers: A workshop Summary Report.

The workshop "Drug Permeability - Best Practices for Biopharmaceutics Classification System (BCS) Based Biowaivers" was held virtually on December 6, 2021, organized by the University of Maryland Center of Excellence in Regulatory Science and Innovation (M-CERSI), and the Food and Drug Administration (FDA). The workshop focused on the industrial, academic, and regulatory experiences in generating and evaluating permeability data, with the aim to further facilitate implementation of the BCS and efficient development of high-quality drug products globally. As the first international permeability workshop since the BCS based biowaivers was finalized as the ICH M9 guideline, the workshop included lectures, panel discussions, and breakout sessions. Lecture and panel discussion topics covered case studies at IND, NDA, and ANDA stages, typical deficiencies relating to permeability assessment supporting BCS biowaiver, types of evidence that are available to demonstrate high permeability, method suitability of a permeability assay, impact of excipients, importance of global acceptance of permeability methods, opportunities to expand the use of biowaivers (e.g. non-Caco-2 cell lines, totality-of-evidence approach to demonstrate high permeability) and future of permeability testing. Breakout sessions focused on 1) in vitro and in silico intestinal permeability methods; 2) potential excipient effects on permeability and; 3) use of label and literature data to designate permeability class.

A multicenter, open-label, prospective, randomized, dose-ranging pharmacokinetic study of the anti-TNF-alpha antibody afelimomab in patients with sepsis syndrome.

OBJECTIVE: To investigate the pharmacokinetics and safety of afelimomab, a murine antibody fragment against human tumor necrosis factor (TNF)-alpha in patients with sepsis. DESIGN: Multicenter, randomized, open-label, placebo-controlled phase I/II clinical trial. SETTING: Intensive care units of six academic medical centers in the United States. PATIENTS: Forty-eight patients with a clinical diagnosis of sepsis who received standard supportive care and antimicrobial therapy. INTERVENTIONS: Patients received 0.3, 1.0, or 3.0 mg/kg afelimomab or placebo intravenously over 20 min. Three patients in each dose group received single doses; the remaining nine patients in each group received multiple (nine) doses at 8-h intervals over 72 h. MEASUREMENTS AND MAIN RESULTS: Afelimomab appeared safe and well tolerated. Single- and multiple-dose kinetics were predictable and dose related. The elimination half-life was 44.7 h. Afelimomab treatment resulted in increased serum concentrations of TNF (includes TNF-antibody complexes) and decreased serum interleukin-6 concentrations, whereas no discernible trends were observed in placebo-treated patients. There was no significant treatment effect on 28-day mortality as was expected given the small number of patients. However, overall mortality was significantly (p = 0.001) associated with baseline interleukin-6 concentration. All patients experienced adverse events, but the vast majority were considered unrelated to the study drug and demonstrated no apparent relationship to afelimomab dose. Although 41% of patients developed human anti-murine antibodies, there were no clinical sequelae. CONCLUSIONS: Multidose therapy with afelimomab was safe, well tolerated, and had predictable linear kinetics. A large randomized trial comparing afelimomab to placebo in patients with well defined sepsis has recently been completed.

Phase I and pharmacokinetic study of LU79553, a DNA intercalating bisnaphthalimide, in patients with solid malignancies.

PURPOSE: To determine the maximum-tolerated dose and characterize the pharmacokinetic behavior of LU79553, a novel bisnaphthalimide antineoplastic agent, when administered as a daily intravenous infusion for 5 days every 3 weeks. PATIENTS AND METHODS: Patients with advanced solid malignancies received escalating doses of LU79553. Plasma sampling and urine collections were performed on both days 1 and 5 of the first course. RESULTS: Thirty patients received 105 courses of LU79553 at doses ranging from 2 to 24 mg/m(2)/d. Proximal myopathy, erectile dysfunction, and myelosuppression precluded the administration of multiple courses at doses above 18 mg/m(2)/d. These toxicities were intolerable in two of six patients after receiving three courses at the 24-mg/m(2)/d dose level. At the 18-mg/m(2)/d dose, one of six patients developed febrile neutropenia and grade 2 proximal myopathy after three courses of LU79553. The results of electrophysiologic, histopathologic, and ultrastructural studies supported a drug-induced primary myopathic process. A patient with a platinum- and taxane-resistant papillary serous carcinoma of the peritoneum experienced a partial response lasting 22 months. Pharmacokinetics were dose-independent, optimally described by a three-compartment model, and there was modest drug accumulation over the 5 days of treatment. CONCLUSION: Although no dose-limiting events were noted in the first two courses of LU79553, cumulative muscular toxicity precluded repetitive treatment with LU79553 at doses above 18 mg/m(2)/d, which is the recommended dose for subsequent disease-directed evaluations. The preliminary antitumor activity noted is encouraging, but the qualitative and cumulative nature of the principal toxicities, as well as the relatively small number of patients treated repetitively, mandate that rigorous and long-term toxicologic monitoring be performed in subsequent evaluations of this unique agent.

A phase I clinical and pharmacokinetic study of the dolastatin analogue cemadotin administered as a 5-day continuous intravenous infusion.

PURPOSE: The dolastatins are a class of naturally occurring cytotoxic peptides which function by inhibiting microtubule assembly and tubulin polymerization. Cemadotin is a synthetic analogue of dolastatin 15 with potent antiproliferative and preclinical antitumor activity. This report describes a phase I study to evaluate the administration of cemadotin to adult cancer patients by a 5-day continuous intravenous (CIV) infusion. METHODS: All patients had histologically confirmed refractory solid tumors. The dose was escalated from an initial level of 2.5 mg/m2 (0.5 mg/m2 daily) according to a modified Fibonacci algorithm. A minimum of three patients was evaluated at each dose level until the maximum tolerated dose (MTD) was established. Treatment was repeated every 21 days until patients were removed from the study due to toxicity or disease progression. Drug-related toxicities were evaluated and graded by the U.S. National Cancer Institute's Common Toxicity Criteria. A radioimmunoassay (RIA) that detected both the parent drug and its metabolites with an intact N-terminal region of the molecule was used for pharmacokinetic studies. RESULTS: Twenty heavily pretreated patients received a total of 40 courses of cemadotin over five dose levels ranging from 2.5 to 17.5 mg/m2. Reversible dose-related neutropenia was the principal dose-limiting toxicity and 12.5 mg/m2 was established as the MTD. Nonhematologic toxicities attributed to the drug were moderate, and there was no evidence of the cardiovascular toxicity noted in the prior phase I studies of cemadotin given IV as a 5-min injection or 24-h infusion. There were no objective antitumor responses. Time courses of the cemadotin RIA equivalent concentration in whole blood were defined in 14 patients during the first cycle of therapy. The RIA-detectable species exhibited apparent first-order pharmacokinetics across the entire range of doses. The mean +/- SD of the observed steady-state blood concentration at the 12.5 mg/m2 MTD was 282 +/- 7 nM (n = 3). Blood levels decayed monoexponentially following the end of the infusion, with a mean half-life of 13.2 +/- 4.3 h (n = 14) in all patients. Mean values (n = 14) of the total blood clearance and apparent volume of distribution at steady state were 0.52 +/- 0.09 lh/m2 and 9.9 +/- 3.3 l/m2, respectively. CONCLUSIONS: The cardiotoxic effects of cemadotin were completely avoided by administering it as a 120-h CIV infusion. Thus. cardiovascular toxicity appears to be associated with the magnitude of the peak blood levels of the parent drug or its metabolites, whereas myelotoxicity is related to the duration of time that blood levels exceed a threshold concentration. Nevertheless, the data acquired during the extensive clinical experience with cemadotin requires careful examination to assess whether advancing this compound into disease-oriented efficacy studies is merited.

Phase I and pharmacokinetic study of the water-soluble dolastatin 15 analog LU103793 in patients with advanced solid malignancies.

PURPOSE: To determine the maximum-tolerated dose (MTD), dose-limiting toxicities (DLTs), and pharmacokinetic profile of the dolastatin 15 analog LU103793 when administered daily for 5 days every 3 weeks. PATIENTS AND METHODS: Fifty-six courses of LU103793 at doses of 0.5 to 3.0 mg/m2 were administered to 26 patients with advanced solid malignancies. Pharmacokinetic studies were performed on days 1 and 5 of course one. Pharmacokinetic variables were related to the principal toxicities. RESULTS: Neutropenia, peripheral edema, and liver function test abnormalities were dose-limiting at doses greater than 2.5 mg/m2 per day. Four of six patients developed DLT at 3.0 mg/m2 per day, whereas two of 12 patients treated at 2.5 mg/m2 per day developed DLT. Pharmacokinetic parameters were independent of dose and similar on days 1 and 5. Volume of distribution at steady-state (Vss) was 7.6 +/- 2.0 L/m2, clearance 0.49 +/- 0.18 L/h/m2, and elimination half-life (t1/2) 12.3 +/- 3.8 hours. Peak concentrations (Cmax) on day 1 related to mean percentage decrement in neutrophils (sigmoid maximum effect (Emax) model). Patients who experienced dose-limiting neutropenia had significantly higher Cmax values than patients who did not, whereas nonhematologic DLTs were more related to dose. CONCLUSION: The recommended dose for phase II evaluations of LU103793 daily for 5 days every 3 weeks is 2.5 mg/m2 per day. The lack of prohibitive cardiovascular effects and the generally acceptable toxicity profile support the rationale for performing disease-directed evaluations of LU103793 on the schedule evaluated in this study.

Clinical and pharmacologic phase I study of Cemadotin-HCl (LU103793), a novel antimitotic peptide, given as 24-hour infusion in patients with advanced cancer. A study of the Arbeitsgemeinschaft Internistische Onkologie (AIO) Phase I Group and Arbeitsgruppe Pharmakologie in der Onkologie und Haematologie (APOH) Group of the German Cancer Society.

PURPOSE: To determine the maximum tolerable dose (MTD), principal toxicity, and pharmacologic behaviour of Cemadotin-HCl, a novel antimitotic peptide. PATIENTS AND METHODS: Cemadotin-HCl (10.0 to 27.5 mg/m2/day every three weeks) was administered as a 24-hour intravenous (i.v.) continuous infusion to patients with advanced cancer. Pharmacokinetic analyses were performed during the first treatment cycle. Blood samples were taken over 48 hours and analyzed by radioimmunoassay. RESULTS: Hypertension was the dose-limiting toxicity (DLT). This type of toxicity was observed at all dose levels, but grade 3 (CTC) was observed only at dose levels 20.0, 25.0 and 27.5 mg/m2. This effect was reversible but in three patients associated with signs of cardiac ischemia. Other significant toxic effects were neutropenia, asthenia, tumor pain and transient liver enzyme elevation. A linear pharmacokinetics was observed. The best curve fit was obtained with a two-compartment model with a terminal half-life of approximately 10 hours at each dose level, a volume of distribution at steady state of approximately 9 l/m2 and a total clearance of approximately 0.6 l/hour/m2. Neither partial nor complete responses were observed although minor tumor regressions were seen in a patient with carcinoma of unknown primary (CUP) and in another patient with liver metastases from a colon cancer. CONCLUSIONS: Hypertension was the dose-limiting toxicity of Cemadotin-HCl administered as a continuous 24-hour infusion. The recommended dose for further evaluation of its anticancer efficacy in disease-oriented phase II studies with this schedule is 15.0 mg/m2. The nature of the principal cardiovascular toxicity remains unclear. The observed toxicities appeared to be significant but manageable.

The beagle dog as an animal model for a bioavailability study of controlled-release theophylline under the influence of food.

Beagle dogs were evaluated as an animal model to study the effect of food on the bioavailability of two commercially available oral controlled-release theophylline products. The products were administered with and without food in single doses, and the bioavailability parameters were compared with those following an i.v. aminophylline dose. The total plasma theophylline clearance in dogs following an i.v. dose was 0.128 liter/hr/kg and the volume of distribution was 0.8 liter/kg using a one-compartment model. The absolute bioavailabilities of these two products under fasting conditions were 31 and 48%, respectively. The food increased the bioavailability of one product and decreased the bioavailability of the other. The overall trends in relative bioavailability of these two products with and without food appeared to be similar to those reported in humans.

The effect of food on the absorption of controlled-release theophylline in mini-swine.

The effect of differing fat contents of food on the bioavailability of theophylline following a 400-mg single dose of Theo-24 was studied in mini-swine. The pharmacokinetics of theophylline, following the intravenous administration of aminophylline equivalent to 5 mg/kg as a single dose, were also studied in the same animals. The terminal plasma half-life of theophylline following an i.v. dose was found to be approximately 24 hr. The volume of distribution, Vdext, and clearance following the i.v. dose were approximately 0.7 liter/kg and 0.023 liter/hr/kg, respectively. The terminal half-life of theophylline following the administration of theophylline capsules under fasting conditions was 21 hr. The average bioavailability under fasting conditions was approximately 80% compared to the i.v. dose. Food appeared to have decreased the rate of absorption but no significant effect on the extent of absorption.

Interactions of apomorphine with serum and tissue proteins.

Physical and covalent interactions of apomorphine with serum and tissue proteins could influence the drug's disposition and pharmacological activities in mammals. Ultrafiltration, equilibrium dialysis, and ultraviolet spectrophotometric methods have been used to study the reversible binding of apomorphine to bovine, human, rat, and swine plasma proteins. The degree of binding was generally greater than 90%, but variations were noted in some instances on the basis of drug concentrations and pH over the range of 6.8-7.8. Incubation of [8,9-3H2]apomorphine with bovine serum albumin led to retention of radioactivity and a stoichiometrically controlled released of tritium which arose from the reaction of an electrophilic drug oxidation product and protein, producing drug-protein conjugates. In vitro experiments with mouse striatal brain preparations indicated parallel covalent binding reactions. In vivo experiments in mice indicated accumulation of radioactivity in brain regions and other tissues following daily injections of [8,9-3H2]apomorphine for 14 days. The physical and covalent interactions of apomorphine with mammalian tissue proteins could be the cause of longer disposition half-lives in mammals than those previously reported. The covalent interactions, in particular, may be important in elucidating the mechanism of apomorphine-induced behavioral effects in mice.

The effect of food and antacid on the absorption of fendosal.

Fendosal (200 mg) was given orally to each of two separate groups of twelve healthy male volunteers on separate occasions to assess the influence of food or antacid on the bioavailability of fendosal. Blood samples (20 ml) were drawn during 12 hours post-dosing and fendosal plasma concentrations were quantitated by a validated fluorescence technique. Food was shown to have no significant effect (p greater than 0.05) on fendosal bioavailability. However, the bioavailability of fendosal in the presence of an antacid was reduced by 80 per cent. In vitro studies suggested that a complexation between unionized fendosal and the metal ions contained in the antacid may be responsible for the decrease in the rate and extent of absorption observed in vivo.