PF336 EVALUATION OF THROMBOPOIETIN‐RECEPTOR AGONISTS (TPO‐RAS) «STOP‐THERAPY» IN IDIOPATHIC THROMBOCYTOPENIC PURPURA (ITP)

Background:For a number of years, it has been shown that TPO‐RAs are a highly effective therapy of ITP. Still, there are few published guidelines/recommendations addressing the management of ITP patients (pts) on TPO‐RAs after they achieve continuous remission.Aims:To evaluate the TPO‐RAs «stop‐therapy» in ITP pts with complete response (CR) to TPO‐RAs.Methods:We analyzed data of TPO‐RA «stop‐therapy» in patients with CR. Primary endpoints of the study were the duration and type of response (CR, partial – PR, minor – MR, and loss of response) after TPO‐RAs had been stopped. Secondary endpoints included types of response (CR, PR, MR) after TPO‐RAs had been resumed in those pts who relapsed.Results:194 ITP pts treated at Moscow City Hematology Center (Botkin Hospital) in 2014–2018 were administered TPO‐ARs: (romiplostim (R): n = 123; eltrombopag (E): n = 71). 106 pts (55%) achieved CR (platelets >100х109/l)(R: n = 79 (64%); E: n = 27 (38%).28 pts in continuous CR (≥3 months (mo) had TPO‐RA stopped: (R: n = 19; E: n = 9). Group R (GR) comprised of 4 males and 15 females, with median age (Mе) age at the time of diagnosis of 51 (range 1 ‐ 69) years, and Me follow‐up time from the time of diagnosis was 108 (9 ‐ 483) mo. Group E (GE) included 1 male and 8 females with Me age of 54 (range 12 ‐ 75) years and Me follow‐up time from the time of diagnosis of 74 (27 ‐ 228) mo.Me stop‐therapy length was 69 (range 20 ‐ 276) weeks in GR, and 38 (range 13 ‐ 131) weeks in GE.At the time of analysis, CR was maintained in 5 (26%) GR pts, and in 1 (11%) GE pt. PR was seen in 7 (37%) GR pts and in 2 (23%) GE pts; and MR in 5 (26%) GR pts and in 1 (11%) GE pt. 2 (11%) GR pts and 5 (55%) GE pts did not respond to TPO‐RAs.TPO‐RAs were resumed in 2 GR and 2 GE pts who relapsed (7 pts have relapsed altogether), and 1 PR and 1 MR in each group were achieved.Summary/Conclusion:Our data adds to the growing body of evidence that ITP pts maintain remission after TPO‐RAs are stopped. This may possibly represent a change in therapeutic approach to these patients who usually require continuous maintenance therapy. Longer follow‐up and larger number of pts enrolled in the study are required to fully assess benefits of such approach.