Drs. Claudia Giani, Anna Maria Frezza, Silvia Stacchiotti, and colleagues from the Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy, and Royal Marsden Hospital, London, UK, presented results from POEM: a prospective observational study on Epithelioid Haemangioendothelioma at ESMO Congress 2025.

The data presented included 57 consecutive molecularly confirmed EHE patients who entered the study, with sirolimus offered to patients with evidence of symptomatic and/or radiologic progression (PD).

Median Overall Survival (m-OS) was compared between patients undergoing active surveillance (AS) and those receiving sirolimus. Progression-Free Survival (PFS) was assessed by RECIST v1.1. As additional exploratory endpoints, pain changes were evaluated retrospectively by newly defined Pain Assessment Criteria (PAC); radiologic and effusion changes by Response Evaluation by Serosal Changes and Outcomes Reporting (RESCORe).

Overall, 19 patients received sirolimus. Among patients who started sirolimus while on study due to PD, 3/4 achieved disease stabilization as assessed by RECIST, RESCORe, and PAC, while 1/4 by RECIST and PAC criteria only. m-OS was 163 mos, RECIST m-PFS was not reached, RESCORe m-PFS 52 mos.

The researchers conclude that, in addition to RECIST, other assessment criteria that consider changes in pain and serosal effusion warrant further investigation in EHE to better identify patients requiring treatment and to evaluate therapeutic responses more effectively.

The EHE Foundation, in partnership with the EHE Rare Cancer Charity (UK), sponsors this project and is grateful to the researchers and patients who contribute to these findings.