Clinical Monograph for Drug Formulary Review: Systemic Agents for Psoriasis/Psoriatic Arthritis

BACKGROUND: Significant advances in the pharmacologic treatment of psoriasis,most notably the introduction of the biologic agents efalizumab and alefacept,have occurred recently. In addition, another biologic agent, etanercept, was recently approved for the treatment of psoriasis and psoriatic arthritis, thus adding to the list of biologic agents approved for the treatment of these disease states. A review was conducted by the Drug Information Service of a pharmacy benefits manager (PBM) to determine the relative merits and place in therapy of commonly used systemic agents for the treatment of psoriasis and psoriatic arthritis. OBJECTIVES: To provide readers with a comprehensive clinical monograph on psoriasis and psoriatic arthritis agents, written with a managed care perspective,as used in actual drug formulary decision making by a PBM. METHODS: The drug formulary of this PBM is designed to provide health plans with an evidence-based review of drugs, therapeutic classes, and disease states with a managed care focus. For each therapeutic class or disease review, an extensive and thorough literature search of MEDLINE is conducted for efficacy,safety, effectiveness, and humanistic and economic data. Drug/disease-state databases (UpToDate online, MICROMEDEX), U.S. Food and Drug Administration clinical reviews, key Internet sites, medical/pharmacy-related news sites, clinical guidelines, and AMCP dossiers are also reviewed. Formulary drug monographs produced by the Drug Information Service of the PBM include a critical analysis and summary of disease-oriented and patient-oriented clinical outcomes, effectiveness,and humanistic data. Additional data considered and included in the formulary review process are clinical attributes, patent expirations/generic competition, off-label or pending indications, and pharmacoeconomic data. RESULTS: The biologic agents do not appear to be as efficacious as traditional systemic therapies but are associated with fewer long-term toxicities that oftenlimit treatment duration with traditional systemic agents. Although no head-to head comparisons between alefacept and efalizumab exist, efalizumab appears to offer slightly higher efficacy rates, while alefacept has a longer duration of action. Etanercept at the higher approved dose appears more efficacious comparedwith efalizumab or alefacept for the treatment of psoriasis, and it is the only biologic currently approved for the treatment of psoriatic arthritis. Efalizumaband alefacept are generally well tolerated, but rebound flare of psoriasis associated with efalizumab, thus requiring continuous treatment to avoid a flare in disease. Efalizumab and etanercept can be self-administered by the patient, while alefacept and infliximab require administration by a health care professional. CONCLUSIONS: Systemic therapy is reserved for patients with moderate-to severe psoriasis or patients with psoriatic arthritis. The biologic agents are not as efficacious as traditional therapies but, due to better tolerability, are gaining acceptance in the treatment of psoriasis and psoriatic arthritis. The biologic agents differ in efficacy rates and are generally well tolerated. Clinical attributes,overall efficacy, and economic costs associated with the biologic agents will be significant factors in selecting agents for the treatment of psoriasis and psoriaticarthritis.