Safety and Efficacy of Romiplostim in Immune Thrombocytopenia (ITP) in the “real-life” : Result of the French Experience in 72 Adults.

Romiplostim is a thrombopoietic agent that has been unequivocaly demonstrated as highly effective in adult's ITP in prospective studies and has recently been licensed for adults with chronic ITP in USA, Europe, Canada, and Australia. France has been the only country where romiplostim could be given for a compassionate use outside clinical studies from January 2008. The official indication for obtaining romiplostim in this setting was: chronic ITP according to the international criteria and failure or relapse after at least one previous line of therapy regardless the status towards splenectomy. We report here the data on safety and efficacy of the first consecutive 80 ITP patients who have been registered by the French health authorities as receiving the treatment “off-label” and with at least one-year of follow up.

The data were retrospectively reviewed using a standardized form. The protocol was approved by local ethical committee. Patients who did not fulfil official indication criteria of compassionate use were excluded (i.e. secondary-ITP). Platelet count was monitored at least monthly during the follow-up. Platelet response was defined as platelet count of 50×10⁹/L or more and a doubling of the pre-treatment count in the absence of any rescue medication within the last 8 weeks. One-year sustained response was defined as a platelet response on at least 2 of the last 3 platelet determinations at month-10-11 and 12. Patients who received rescue medication at any time during the study could not be counted as having a one-year sustained response. Report of adverse events was captured using a standardized form.

Among the 80 patients, 8 were actually excluded from the analysis (6 with secondary ITP and 2 have been misdiagnosed as having ITP). The analysis was then conducted on 72 patients (43 females) with a median age of 60 years (20 to 91). The median duration of ITP prior to romiplostim administration was 8.7 years (0.1 to 49) and the patients had received a median of 5 (2 to 12) treatment-lines before romiplostim including: corticosteroids (100%), rituximab (65/72, 90%) and splenectomy (39/72, 54%). Among the 33 non-splenectomized patients, 13 patients were reluctant to undergo splenectomy whereas splenectomy was considered as contra-indicated in 20 of them. At time of romiplostim first administration, median platelet count was 16×10⁹/L (1 to 60) and 48 patients (66%) were receiving a concurrent treatment for ITP, including mainly steroids (n=29) ± immunosuppressive drugs (n=8).

A platelet response was observed at least once in 76% (55/72) of the patients. On average, patients who responded at any point during the study had a platelet response during 64% of the time (range: 37 to 100%). Romiplostim was stopped in 28 % (20/72) of patients for either lack of efficacy (n=16), for intolerance (n=1) or because it was administered only transiently in preparation for surgery (n=3). Two patients had died respectively from a septic shock and from an ITP-related intracranial hemorrhage. At one-year of follow up, 52 patients were still receiving romiplostim at a median dose of 6.5 μg/kg per week. This dose remained relatively stable as after the first 12 weeks of treatment, romiplostim could be pursued at a stable dose ± 2 μg/kg in 82% of the cases. Twenty % (14/72) of patients received a rescue medication during the study and 50% (36/72) of the patients had a one-year sustained response. The percentage of one-year sustained response was similar in splenectomized and non splenectomized groups [respectively 54% (21/39) and 45% (15/33), NS)]. Among the 29 patients who responded to romiplostim and who were receiving a treatment at time of romiplostim initiation, 86 % (25/29) had discontinued this medication and a further 7% (2/29) had reduced the dose by at least 25%.

Only one patient stopped romiplostim because of an adverse event (headache). The most frequent otherwise reported adverse events were: arthralgia (26%), fatigue (13%) and nausea (7%). A transient thrombocytosis > 400×10⁹/L and > 1000×10⁹/L has been observed in respectively 19% (14/72) and 4% (3/72) of patients. A transient stroke occurred in 2 elderly patients (age > 70 yrs). No deep vein thrombosis occurred. Myelofibrosis was not observed.

Our study confirms in “real-life” that romiplostim is definitely an effective and safe treatment for severe chronic ITP in both non-splenectomized and splenectomized adults.

Godeau:AMGEN: Consultancy.