MEK Inhibitors Produce Strong, Sustained Responses in Erdheim–Chester Disease

By
Francesco Pegoraro
Félicien Triboulet
Matthias Papo
Francesco Peyronel
Anita Argentieri
Jerome Razanamahery
Ahmed Idbaih
Polyzois Makras
Ofer Shpilberg
Oshrat Hershkovitz-Rokah
Michael Girschikofsky
Matthew Collin
Kristian Bowles
Satyen H. Gohil
Rodothea Amerikanou
Emmanuel Ledoult
Tanguy Le Scornet
Mathilde de Menthon
Etienne Riviere
Xavier Boulu
Henry Dupuy
Achille Aouba
Stanislas Faguer
Xavier Solanich
Elena Sieni
Stéphane Barete
Chiara Bellino
Alessandro Tomelleri
Corrado Campochiaro
Lorenzo Dagna
Zahir Amoura
Jean-François Emile
Fleur Cohen-Aubart
Augusto Vaglio
Julien Haroche
October 6, 2026

Hemasphere

Objective:

To assess long-term efficacy, tolerability, and baseline factors associated with response to MEK inhibitor (MEKi) monotherapy in Erdheim–Chester disease (ECD).

Approach:

Study design: International cohort study across eight countries of patients with biopsy-proven Erdheim–Chester disease (ECD) or mixed histiocytosis treated with MEK inhibitor (MEKi) monotherapy.
Eligibility and assessment: Eligibility required available treatment and outcome data and at least 6 months of follow-up. Medical-chart review assessed response using clinical, radiologic, and metabolic criteria; adverse events were evaluated using CTCAE criteria.
Analysis: Prespecified outcomes included response, time to best response, treatment retention, toxicity, event-free survival, and overall survival. Time-dependent response was analyzed using hazard ratios, with univariate and multivariate Cox analyses of candidate covariates.

Key Findings:

Of 206 patients screened across eight countries, 170 were included. Twenty-four were excluded for clinical-trial enrollment, seven for not reaching the initial response assessment, and five for missing follow-up data.

Interpretation:

The provided article context describes the study design and baseline cohort characteristics but does not include the treatment-response, toxicity, survival, or predictor results needed to substantiate the title’s claims.

Limitations:

The supplied context ends during the baseline characteristics section and does not provide the main efficacy, safety, survival, or predictor results.
The study used medical-chart review and was observational.