Superior efficacy and similar safety of double dose anakinra in Erdheim-Chester disease after single dose treatment.

Objectives. In Erdheim-Chester disease (ECD), the empirical single dose (SD, 100 mg/day) anakinra sometimes induces only partial responses. Since SD is usually well tolerated, doubling the dose might improve response while maintaining an acceptable safety profile. Methods. A retrospective analysis was performed of outcomes under double-dose (DD) of anakinra in 4 ECD patients who did not exhibit a complete response (CR) under SD treatment. Bone, retroperitoneal, neurologic/orbital, peritoneal, pericardial, right atrium, and pleural involvements were recorded. CR, partial response (PR), stable disease, progressive disease (PD) and tolerance of DD were assessed. Results. SD treatment was a second or third line treatment in three patients after interferon-therapy failure. Two patients, including one with a BRAF mutation, achieved a CR and one patient with a NRAS mutation achieved a PR with DD treatment. The fourth patient, wild-type for both genes, did not respond to a first DD treatment, but then achieved CR under SD associated with a reduced dose of vemurafenib (960 mg/d). Bone and retroperitoneal lesions partially improved on imaging with SD in all patients, but were further improved under DD with two patients achieving CR. With SD treatment, two patients with right atrial masses showed sustained CR. Under DD treatment, two patients with massive serositis refractory to SD, showed PR. Conclusion. DD improved the response to anakinra and lead to two CRs and a PR in three out of four ECD patients, with minor and comparable side-effects to those of SD, while failures were essentially related to massive serositis.