Biosimilars: what the dermatologist should know

Biosimilars are highly similar versions of approved branded biologics. In contrast to generics, which are identical copies of the originator medicines, biosimilars are considered unique but related molecules that differ from the originator reference product as well as from each other. Owing to the complexity of biologic medicines, such as therapeutic monoclonal antibodies, minor differences between biosimilars and the reference products are acceptable provided these differences do not result in any clinically meaningful differences in safety or efficacy. In addition, minor changes in structure and function may occur over time in originator biologic products as a result of alterations in production materials (e.g. cell lines), processes or conditions. The developmental process for biosimilars focuses on a 'totality of evidence' approach that emphasizes a stepwise investigational process, including comprehensive structural, functional, pharmacologic and clinical assessment for similarity. The goal of the phase 3 clinical development programme for a biosimilar is not to establish efficacy, per se, but to demonstrate that there are no clinically meaningful differences between the proposed biosimilar and the reference product. The requirement to show clinical similarity informs biosimilar study design, including the selection of the patient population, disease state (indication), study endpoints and statistical methods. Based on the clinical trial results in a representative patient population, results may be extrapolated to other indications provided scientific justification is demonstrated based on, among other things, similar mechanism of action in the extrapolated indications. This review presents the current state of knowledge with respect to biosimilars. We aim to provide the practising clinician with a working knowledge of biosimilars as well as provide some practical guidance on their use and potential benefits in treating dermatologic diseases.

Effects of etanercept on C-reactive protein levels in psoriasis and psoriatic arthritis

BACKGROUND

C-reactive protein (CRP), an inflammation biomarker, indicates cardiovascular risk and is elevated in psoriasis. The effect of etanercept on CRP in psoriasis has not been previously examined.

OBJECTIVES

The primary objective was to examine the effect of etanercept on CRP levels from baseline to week 12 compared with placebo. Secondary objectives included assessment of baseline CRP and relationships between CRP and body mass index (BMI), statin drug use, and Psoriasis Area and Severity Index (PASI) scores.

METHODS

A retrospective analysis was conducted of CRP levels from patients with psoriasis who participated in a randomized, double-blind, placebo-controlled, U.S. registrational study. Data were analysed separately if patients self-reported psoriatic arthritis.

RESULTS

Baseline CRP levels were elevated in patients with psoriasis with and without psoriatic arthritis. CRP was significantly reduced in both groups after 12 weeks of etanercept treatment. Patients with psoriasis with psoriatic arthritis and patients with higher BMIs had higher median baseline CRP values and greater reduction of CRP values compared with those without psoriatic arthritis and those with lower BMIs. Etanercept lowered CRP levels in statin users and nonusers. Regression analyses revealed an association between baseline PASI score and baseline CRP independent of BMI in patients with psoriasis.

CONCLUSIONS

Patients with moderate to severe plaque psoriasis, with or without psoriatic arthritis, have increased systemic inflammation demonstrated by elevated CRP levels. In psoriasis without psoriatic arthritis, skin disease activity is associated significantly with CRP elevation, independent of BMI, age and sex. Etanercept reduced CRP levels in all but the normal weight psoriasis group without psoriatic arthritis.

Etanercept for severe psoriasis and psoriatic arthritis: observations on combination therapy

BACKGROUND

The antitumour necrosis factor (TNF) activity of etanercept has been utilized to generate an important and novel treatment for rheumatoid arthritis. TNF has also been implicated in the pathogenesis of psoriasis.

OBJECTIVES

To determine whether blockade of TNF activity by etanercept may provide an additional treatment option for patients with psoriasis.

METHODS

In an uncontrolled trial, etanercept was added to the treatment regimen in six patients with severe recalcitrant psoriasis (three also with psoriatic arthritis) partially resistant to other ongoing systemic agents.

RESULTS

In each case, the disease activity showed marked improvement on addition of etanercept therapy. No added toxicity was found with etanercept.

CONCLUSIONS

Etanercept appears to be a promising immunomodulatory agent that can be used in combination therapy for the treatment of psoriasis, and a prospective controlled trial may be warranted.

The function of a ribosomal frameshifting signal from human immunodeficiency virus-1 in Escherichia coli

A 15-17 nucleotide sequence from the gag-pol ribosome frameshift site of HIV-1 directs analogous ribosomal frameshifting in Escherichia coli. Limitation for leucine, which is encoded precisely at the frameshift site, dramatically increased the frequency of leftward frameshifting. Limitation for phenylalanine or arginine, which are encoded just before and just after the frameshift, did not significantly affect frameshifting. Protein sequence analysis demonstrated the occurrence of two closely related frameshift mechanisms. In the first, ribosomes appear to bind leucyl-tRNA at the frameshift site and then slip leftward. This is the 'simultaneous slippage' mechanism. In the second, ribosomes appear to slip before binding aminoacyl-tRNA, and then bind phenylalanyl-tRNA, which is encoded in the left-shifted reading frame. This mechanism is identical to the 'overlapping reading' we have demonstrated at other bacterial frameshift sites. The HIV-1 sequence is prone to frame-shifting by both mechanisms in E. coli.