Assessment of romiplostim immunogenicity in adult patients in clinical trials and in a global postmarketing registry

Antibodies to first‐generation recombinant thrombopoietin (TPO) neutralized endogenous TPO and caused thrombocytopenia in some healthy subjects and chemotherapy patients. The second‐generation TPO receptor agonist romiplostim, having no sequence homology to TPO, was developed to avoid immunogenicity. This analysis examined development of binding and neutralising antibodies to romiplostim or TPO among adults with immune thrombocytopenia (ITP) in 13 clinical trials and a global postmarketing registry. 60/961 (6·2%) patients from clinical trials developed anti‐romiplostim‐binding antibodies post‐baseline. The first positive binding antibody was detected 14 weeks (median) after starting romiplostim, at median romiplostim dose of 2 µg/kg and median platelet count of 29.5 × 10⁹/l; most subjects had ≥98·5% of platelet assessments showing response. Neutralising antibodies to romiplostim developed in 0·4% of patients, but were unrelated to romiplostim dose and did not affect platelet count. Thirty‐three patients (3·4%) developed anti‐TPO‐binding antibodies; none developed anti‐TPO‐neutralising antibodies. In the global postmarketing registry, 9/184 (4·9%) patients with spontaneously submitted samples had binding antibodies. One patient with loss of response had anti‐romiplostim‐neutralising antibodies (negative at follow‐up). Collectively, anti‐romiplostim‐binding antibodies developed infrequently. In the few patients who developed neutralising antibodies to romiplostim, there was no cross‐reactivity with TPO and no associated loss of platelet response.

Assessment of Self-Administration of Romiplostim in Patients with Immune Thrombocytopenic Purpura after Receipt of Home Administration Training Materials: a Cross-Sectional Study

Introduction

Romiplostim is a subcutaneously administered thrombopoietin-receptor agonist approved in the European Union for self-administration (or administration by a caregiver) in selected adult patients with chronic primary immune thrombocytopenia refractory to other treatments. To mitigate the risk of medication errors due to self-administration, the manufacturer has implemented additional risk minimisation measures (RMM) in the form of a Home Administration Training (HAT) pack to support the training of both healthcare professionals (HCPs) (guide and checklist for patient selection and training) and patients (a preparation mat, quick guide booklet, step-by-step guide, self-administration diary and DVD/video).

Objective

The primary objective was to estimate the proportion of patients/caregivers who administered romiplostim correctly after HAT pack training.

Methods

A multicentre observational study was conducted to evaluate the effectiveness of the HAT pack by recording data on a standardised collection form during direct observation of patients/caregivers in the act of administering romiplostim at the first standard-of-care visit 4 weeks after training with the HAT pack.

Results

Among the 40 patients/caregivers enrolled across 12 study centres in eight European countries, 35 [87.5%; 95% confidence interval (CI) 73.9–94.5] administered romiplostim correctly, and five (12.5%; 95% CI 5.5–26.1) did not.

Conclusion

The correct administration of romiplostim by most patients/caregivers supports the effectiveness of the HAT pack as an additional risk minimisation tool in the population and setting of this study.

The negative effect of red tape on research

PURPOSES

To describe the kind of the difficulties encountered when seeking research governance approval for a nationwide public health and genetic study-the Drug-Induced Arrhythmia Risk Evaluation study-in England.

METHODS

Description of the processes followed when seeking research governance approval for the Drug-Induced Arrhythmia Risk Evaluation study-a case control study with annual follow-up of cases and controls over 5 years, set in the English National Health Service (NHS).

RESULTS

The authors describe wide variations in NHS research governance approval procedures in England.

CONCLUSION

NHS research governance procedures in England are impeding the process of epidemiological studies; there is the need for a centralised NHS R&D approval of studies, which is analogous to MREC for ethical approval.

Evaluation of the safety of sildenafil for male erectile dysfunction: experience gained in general practice use in England in 1999

OBJECTIVE

To examine the safety of sildenafil, the first of the phosphodiesterase type 5 inhibitors licensed for the treatment of male erectile dysfunction (ED), as used in general medical practice in England, quantifying the incidence of a range of events in patients treated with sildenafil, and identifying any previously unrecognized adverse drug reactions.

METHODS

In a postmarketing observational cohort study using prescription-event monitoring (PEM), exposure data were derived from dispensed prescription details for patients who started treatment between April and August 1999. Outcome data were derived from "green form" questionnaires (GFs) returned by general practitioners (GPs). RESULTS In all, 24 835 (54.7%) of GFs posted to GPs were returned, of which 22 473 contained useful data for 22 471 male and two female patients. The major primary indications/clinical context of prescribing were impotence (16 583, 73.8%) and diabetes mellitus (183, 0.8%); 145 events were reported as adverse drug reactions to sildenafil. GPs recorded 3951 reasons for stopping sildenafil, and ischaemic heart disease (IHD) in 135 patients was the commonest clinical reason reported. The clinical condition reported most frequently in the first month of observation was diabetes mellitus and/or hyperglycaemia (in 99 events). A standardized mortality ratio (SMR) for deaths caused by IHD in the first 8893 of 22 473 patients was 31.41 (95% confidence interval 18.29-50.29), using the comparator population of males in England in 1998.

CONCLUSION

This study identified the safety profile of sildenafil as used in the community, showing no unexpected events. The SMR analysis of deaths from IHD provided no evidence to suggest a higher incidence of deaths in the study cohort than in the male population in England.

A case of nonarteritic ischemic optic neuropathy (NAION) in a male patient taking sildenafil

Sildenafil is a phosphodiesterase-type-5 inhibitor indicated for the treatment of erectile dysfunction in men. We report a case of NAION identified from a cohort of 8,893 patients (from a Prescription-Event Monitoring study) prescribed sildenafil by their primary care physician in England between April and June 1999. This 61-year-old patient had risk factors for NAION independent of drug therapy. It was not possible to be confident about a causal association between sildenafil and NAION, though the possibility could not be ruled out. Epidemiological data suggest that one case of NAION might be expected in a cohort of 8,893 subjects. Thus it remains important for clinicians to consider the range of risk factors for NAION; while equally, the processes of pharmacovigilance need to continue as for any recently launched drug preparation.