The U.S. Food and Drug Administration's Experience with Ivacaftor in Cystic Fibrosis. Establishing Efficacy Using In Vitro Data in Lieu of a Clinical Trial.

On May 17, 2017, the U.S. Food and Drug Administration expanded the patient population for use of ivacaftor to include patients with cystic fibrosis with relatively rare mutations in the cystic fibrosis transmembrane conductance regulator gene. The label expansion is unique in that clinical efficacy was not based on clinical data but on in vitro assay data demonstrating increased chloride ion transport across cells in response to ivacaftor. Such an approach provides a pathway for adding difficult-to-study mutation-based cystic fibrosis subpopulations to the indication as well as defining mutations unresponsive to ivacaftor and has important implications for cystic fibrosis drug development and other rare genetic diseases whose genetics and disease pathophysiology are well understood.

Change in sweat chloride as a clinical end point in cystic fibrosis clinical trials: the ivacaftor experience.

Cystic fibrosis (CF) is a life-shortening inherited disease caused by mutations in the CF transmembrane conductance regulator gene (CFTR), which encodes for the CF transmembrane conductance regulator (CFTR) ion channel that regulates chloride and water transport across the surface of epithelial cells. Ivacaftor, a drug recently approved by the US Food and Drug Administration, represents the first mutation-specific therapy for CF. It is a CFTR channel modulator and improves CFTR function in patients with CF who have a G551D mutation. A clinical trial performed to support ivacaftor dose selection demonstrated a dose-response relationship between improvement in FEV(1) and decrease in sweat chloride, a measure of CFTR function. Validation of such a relationship between FEV(1) and sweat chloride would facilitate development of new drugs that target the defective CFTR. Subsequently, in phase 3 studies, ivacaftor 150 mg bid resulted in significant improvements in FEV(1) (10%-12%) and reduction in sweat chloride (approximately 50 mmol/L). However, a decrease in sweat chloride did not correlate with improvement in FEV(1), nor did there appear to be a threshold level for change in sweat chloride above which an improvement in FEV(1) was apparent. The lack of correlation of sweat chloride with improvement in FEV(1) speaks to the multiplicity of factors, physiologic, environmental, and genetic, that likely modulate CF disease severity. Future clinical trials of drugs that are directed to the defective CFTR will need take into account the uncertainty of using even established measurements, such as sweat chloride, as clinical end points.

Inhaled fluticasone propionate by diskus in the treatment of asthma: a comparison of the efficacy of the same nominal dose given either once or twice a day.

STUDY OBJECTIVE: In September 2000, the US Food and Drug Administration (FDA) approved the use of Flovent Diskus (FD) [fluticasone propionate; GlaxoSmithKline; Research Triangle Park, NC], which is an orally inhaled, dry-powder corticosteroid, for the maintenance treatment of asthma at dosages of 50 to 1,000 microg administered twice-daily. Once-daily dosage regimens did not receive approval. This article will detail six clinical trials, five of which incorporated comparative once-daily and twice-daily treatment arms of the same nominal dose of FD. DESIGN: Six 12-week, randomized, double-blind, placebo-controlled studies in patients with mild-to-moderate asthma, including two pediatric asthma trials (patient age, 4 to 11 years) of total daily doses of fluticasone propionate (FP) of 100 or 200 microg, and four adult and adolescent studies of total daily doses of FP of 100, 200, or 500 microg. RESULTS: Twice-daily dosing was numerically superior to once-daily dosing at the same nominal dose in all comparative studies for the primary end point, change in predose FEV(1). In five trials, the results of the once-daily dosage of FP were statistically indistinguishable from those with placebo. One trial demonstrated the superiority of FP, 500 microg once-daily, over placebo; however, the effect size was half that observed with twice-daily dosing. Once-daily FP dosing showed no advantage in safety or in patient adherence to medication. CONCLUSIONS: In the FDA review of once-daily dosing of the FD regimen, 100 or 200 microg once-daily dosing was not shown to be significantly better than placebo. FP 500 microg once-daily was found to be superior to placebo, but at about one half the effect size as the same nominal dose given bid. No advantage in patient safety or adherence was demonstrated for once-daily administration over twice-daily administration, and once-daily administration is not currently recommended.

Improving the quality of adverse drug reaction reporting by 4th-year medical students.

PURPOSE: Evaluate whether a 15-minute lecture intervention will improve adverse drug reaction reporting quality on standard MedWatch forms. METHODS: Seventy-eight 4th-year medical students were randomized to intervention 'Group-A' or non-intervention 'Group-B' on the first day of a required five-day clinical pharmacology rotation. Group-A participants attended a 15-minute lecture on completing a MedWatch form with quality information considered by the Food and Drug Administration as critical to adequate adverse drug reaction reporting. Group-B participants did not attend this lecture. Both groups then watched a standardized patient interview of a recognizable adverse drug reaction and completed MedWatch forms. Four Safety Evaluators from the Food and Drug Administration (FDA) rated student responses in a blinded fashion for the primary efficacy variable of Overall Impression and six informational domins using a standardized data quality analysis form that was developed within the Office of Postmarketing Drug Risk Assessment of the FDA. RESULTS: Seventy-eight MedWatch forms were evaluated (Group-A = 40, Group B = 38). Overall MedWatch information quality scores for the intervention group were significantly higher than the non-intervention group (p < 0.004). CONCLUSIONS: As little as a 15-minute intervention can significantly improve the quality of adverse drug reaction reporting by 4th-year medical students. Academic medical centers should consider incorporating adverse drug reaction reporting curriculum into the clinical training of medical students.

Global Ratings of Student Performance in a Standardized Patient Examination: Is the Whole More than the Sum of the Parts?

Standardized patient examinations (SPE) are widely used in medical education to assess skills that cannot be measured with written examinations. Trained actors termed standardized patients (SPs) are used to simulate patients with specific medical problems. SPs typically use behaviorally specific checklists and rating scales to evaluate examinees. This study explored the use of faculty and SP global ratings of students' clinical and interpersonal skills in an SPE. The reliability of global ratings was found to on par with more specific behaviorally anchored ratings. Global ratings were also found to be predictive of written tests of clinical knowledge and ratings of actual clinical performance after controlling for behaviorally anchored ratings. Faculty global ratings were more reliable and more predictive of other performance than SP global ratings. These results suggest global ratings by faculty observers and possibly SPs can provide unique and useful information in these performance-based examinations.