The 5-point Investigator’s Global Assessment (IGA) Scale: A modified tool for evaluating plaque psoriasis severity in clinical trials

Abstract

Background: To evaluate new psoriasis treatments, clinicians, regulators and pharmaceutical developers require well-accepted, clinically meaningful measures of disease severity. The Psoriasis Area and Severity Index (PASI) score is most widely used as a primary endpoint in clinical trials, although it is not routinely used in clinical practice. Objective: Characterize a 5-point Investigator’s Global Assessment (IGA) tool and evaluate whether it meets the needs for a valid, clinically meaningful measure. Methods: A 5-point IGA tool was developed with input from regulatory authorities and clinical trial investigators involved with psoriasis drug development and evaluation. Associations between IGA 0/1 responder rates and PASI scores were evaluated using data from two phase 2 studies with the anti-interleukin (IL)-17A monoclonal antibody secukinumab (AIN457) that utilized a similar 6-point IGA. Results: The 5-point IGA has a more stringent definition for a score of 1 (“almost clear”) compared with 6-point IGA/Physician’s Global Assessment (PGA) tools used in previous trials of other biologics in moderate-to-severe psoriasis. Whereas IGA/PGA 0/1 responder rates for earlier scales are strongly associated with PASI 75, the IGA 0/1 rate for the secukinumab 6-point scale was more robust, demonstrating a strong association with PASI 90, and the results for the 5-point IGA are expected to show the same association. Discussion: The 5-point IGA is a valid measure of disease severity and meets the need for a clinically meaningful measure of success for psoriasis treatment studies.

• IL-17
• Investigator’s Global Assessment
• Physician’s Global Assessment
• Psoriasis Area and Severity Index
• secukinumab

Acknowledgements

We would like to thank David A. D. Jones for his excellent support during the interactions with regulatory bodies during the development of the IGA mod 2011 scale and Achim Güttner, who has provided expert statistical assessments of the scales during development and implementation. We would also like to thank BioScience Communications of New York, NY, USA, for providing editorial support during the writing of this publication.

Declaration of interest

R. Langley has served as a consultant, an investigator, or an advisory board member for AbbVie, Amgen Inc., Celgene Corp, Eli Lilly & Company, Janssen Pharmaceuticals Inc., LEO Pharma Inc., Novartis Pharmaceuticals Corporation, and Pfizer Inc. S. Feldman has served as a speaker or consultant for, or received grant/research support from 3M, Abbott Laboratories, American Acne & Rosacea Society, American Society for Dermatologic Surgery, Amgen Inc., Astellas Pharma US Inc., Aventis Pharmaceuticals, Bristol-Myers Squibb, Caremark LLC, Celgene Corp, Centocor Biotech, Coria/Healthpoint/Valeant Pharmaceuticals International Inc., Dermatology Foundation, Galderma Laboratories LP, Halcyon Pharmaceuticals Ltd, HanAll Pharmaceutical Co Ltd, Kikaku America International, LEO Pharma Inc./Peplin Inc., Medicis Pharmaceutical Corp, Medscape, Merck & Co Inc., National Biological Corp, National Psoriasis Foundation, Novartis Pharmaceuticals Corporation, Ortho Pharmaceutical, PharmaDerm/Nycomed, PhotoMedex Inc., Roche, Stiefel Laboratories Inc./GlaxoSmithKline, Suncare Research Laboratories, Taro Pharmaceutical Industries Ltd, and Warner Chilcott. He is founder of/stockholder in Causa Technologies and founder of/majority stockholder in Medical Quality Enhancement Corporation, and holds stock options in PhotoMedex. He receives royalties from Xlibris and Informa Healthcare. J. Nyirady is an employee of Novartis Pharmaceuticals Corporation. As an employee, she receives stock options as part of compensation. P. van de Kerkhof has served as a consultant for and received grant support from Abbott Laboratories, Almirall SA, Amgen Inc., Basilea Pharmaceutica Ltd, Celgene Corp, Centocor Biotech, Eli Lilly & Co, Galderma Laboratories LP, Janssen-Cilag, LEO Pharma Inc., Novartis Pharmaceuticals Corporation, Pfizer Inc., Philips Healthcare, and Philips Lighting. C. Papavassilis is an employee of Novartis Pharmaceuticals Corporation. As an employee, he receives stock options as part of compensation. BioScience Communications, New York, NY, USA, provided writing and editorial assistance, supported by Novartis Pharma AG.