Experts query case for GlaxoSmithKline's new 3-in-1 lung drug

LONDON (Reuters) - Two medical experts have urged caution in using a new three-in-one inhaler for chronic lung disease from GlaxoSmithKline (GSK.L), which the company hopes will help it keep its lead in respiratory medicine despite rising competition.

Trelegy Ellipta was licensed for use last year and full results from a positive clinical trial were published on Wednesday in the New England Journal of Medicine (NEJM). A critical accompanying editorial, however, may make some doctors think twice before writing prescriptions.

Trelegy is the first once-daily triple medicine for chronic obstructive pulmonary disease (COPD), putting GSK ahead of rivals such as AstraZeneca (AZN.L) and Novartis (NOVN.S), and it showed benefits over other treatments in the study.

But Dr. Samy Suissa of Canada's McGill University and NEJM editor Dr. Jeffrey Drazen said the design of GSK's clinical trial, known as IMPACT, may have artificially inflated its observed effectiveness.

"As such, we think that the IMPACT trial falls short of providing the awaited robust evidence to better understand the potential for stepping up to single-inhaler triple therapy in clinical practice," they wrote.

GSK said it did not believe the editorial presented an accurate picture of Trelegy's benefit-risk profile, adding that the critique reflected the long-held views of Suissa.

The British drugmaker views Trelegy as a critical new product, along with shingles vaccine Shingrix, as it seeks to fill a revenue gap left by falling sales of the older lung drug Advair, which could face U.S. generic competition this year.

(Reporting by Ben Hirschler; Editing by Elaine Hardcastle)