Exaggeration of PFS by blinded, independent, central review (BICR)

BACKGROUND

Recent published studies have shown meaningful discrepancies between local investigator and blinded, independent, central review (BICR) assessed median progression-free survival (PFS). When the local review but not BICR shows progression, generally, no further assessments are carried out and patients are censored in the BICR analysis, leading to violation of the statistical assumptions of independence between censoring and outcome used in survival analysis methods.

METHODS

We carried out a simulation study to assess methodological reasons behind these discrepancies and corroborated our findings in a case study of three BRCA-mutated ovarian cancer trials. We briefly outline possible methodological solutions that may lead to improved estimation of the BICR medians.

RESULTS

The Kaplan-Meier (KM) curve for the BICR PFS can often be exaggerated. The degree of bias is largest when there is reasonably strong correlation between BICR and local PFS, especially when PFS is long compared with assessment frequency. This can result in an exaggeration of the medians and their difference; however, the hazard ratio (HR) is much less susceptible to bias. Our simulation shows that when the true BICR median PFS was 19 months, and patients assessed every 12 weeks, the estimated KM curves were materially biased whenever the correlation between BICR and local PFS was 0.4 or greater. This was corroborated by case studies where, in the active arm, the BICR median PFS was between 6 and 11 months greater than the local median PFS. Further research is required to find improved methods for estimating BICR survival curves.

CONCLUSIONS

In general, when there is a difference between local and BICR medians, the true BICR KM curve is likely to be exaggerated and its true median will probably lie somewhere between the observed local and BICR medians. Presentation of data should always include both BICR and local results whenever a BICR is carried out.

Effect of an inhaled adenosine A2A agonist on the allergen-induced late asthmatic response

BACKGROUND

Adenosine receptor activation is suggested to play a role in asthmatic airway inflammation. Inhibition of adenosine receptors may have an effect on the late asthmatic response (LAR) after allergen inhalation and this mechanism could offer a potential new treatment in asthma.

METHODS

We evaluated the effect of an inhaled adenosine-(2A) (A(2A))-receptor agonist (GW328267X), 25 microg, in 15 nonsmoking atopic asthmatics who underwent an inhaled allergen challenge following twice daily treatment for 1 week in a double-blind, placebo- and fluticasone propionate (250 microg) controlled study.

RESULTS

In contrast to fluticasone, treatment with the A(2A)-receptor agonist neither significantly protect against the allergen-induced early and late asthmatic reaction, nor the accompanying inflammatory response as measured by sputum total cell counts, number of EG2+ cells, and the concentration of interleukin-8 and eosinophil cationic protein.

CONCLUSION

The inhaled A(2A)-receptor agonist, GW328267X, 25 microg does not affect the allergen-induced LAR or the associated inflammatory response in asthma.

Effect of encapsulation on absorption of sumatriptan tablets: data from healthy volunteers and patients during a migraine

BACKGROUND

Some comparative trials of selective serotonin 1B/ID-agonists in migraine have reported -15% lower efficacy for sumatriptan tablets than that reported in placebo-controlled trials.

OBJECTIVE

This study was designed to test the hypothesis that the encapsulation methods used to mask active drug may delay absorption of sumatriptan from dosing to 2 hours after dosing (the traditional end point in clinical trials of migraine treatment), an effect that may be enhanced by migraine-associated gastric stasis.

METHODS

Two randomized, open-label, 2-way crossover trials were conducted to evaluate the absorption and bioequivalence of conventional 50-mg sumatriptan tablets and encapsulated 50-mg sumatriptan tablets in supine, fasted, healthy volunteers (Glaxo Wellcome protocol SUM40270) and supine patients experiencing a migraine (Glaxo Wellcome protocol SUM40268). Absorption was assessed by calculating the area under the plasma concentration-time curve from dosing to 2 hours after dosing (AUC2) and the times to first measurable plasma concentration, 10 ng/mL, 20 ng/mL, and maximum plasma concentration. Data for the AUC from time zero to infinity and maximum plasma concentration were used to assess standard bioequivalence, which is considered to occur when the 90% CIs for the geometric mean treatment ratios (test/reference) fall between 0.8 and 1.25.

RESULTS

Study 1 included 26 healthy subjects (73% men, 27% women; mean age, 39.1 years), and study 2 included 30 patients with migraine (67% women, 33% men; mean age, 42.7 years). Sumatriptan absorption was delayed with the encapsulated tablet compared with the conventional tablet 0 to 2 hours after dosing, particularly during a migraine. AUC2 values with encapsulated sumatriptan compared with the conventional tablet were 21% lower in healthy volunteers (ratio of capsule/tablet, 0.79; 90% CI, 0.588-1.050) and 27% lower in patients experiencing a migraine (ratio of capsule/tablet, 0.73; 90% CI, 0.519-1.023). Standard bioequivalence was demonstrated in both healthy volunteers and patients experiencing a migraine.

CONCLUSIONS

Encapsulation delayed absorption of sumatriptan 0 to 2 hours after dosing, particularly during a migraine. This delay in absorption of the encapsulated form may account for the lower efficacy of sumatriptan in some comparative studies.

Wearing of caps and masks not necessary during cardiac catheterization

Although cardiac catheterization-related infections are rare, caps and masks are often worn to minimize this complication. However, documentation of the value of caps and masks for this purpose is lacking. We, therefore, prospectively evaluated the experience of 504 patients undergoing percutaneous left heart catheterization, seeking evidence of a relationship between whether caps and/or masks were worn by the operators and the incidence of infection. No infections were found in any patient, regardless of whether a cap or mask was used. Thus, we found no evidence that caps or masks need to be worn during percutaneous cardiac catheterization.