TPO-RAs in pITP: description of a case series and analysis of predictive factors for response

To report our experience concerning sustained response (SR) after TPO-RA discontinuation in adult pITP patients and to identify possible predictive factors for outcome.

Thirty-nine pITP patients who received a TPO-RA were evaluated. Response (R) was defined as a platelet count ≥30 × 10⁹ /L and at least a twofold increase in the baseline count and complete response (CR) as a platelet count ≥100 × 10⁹ /L, in the absence of bleeding. Durable response (DR) was defined as a R/CR persisting ≥4 wk with a stable dose of TPO-RA, and SR as the first assessed platelet count ≥30 × 10⁹ /L, available at more than 4 wk after discontinuation of TPO-RA, in the absence of other concomitant or rescue therapies.

Twenty-nine/39 (74%) were responders: 18 (46%) reached a CR and 11 (28%) a R. A DR was observed in 16/29 (55%) responders. Seven SR (18%) were reached: five of seven patients achieved a SR from a prior DR. CR was statistically associated with the achievement of a subsequent DR: 13/18 (72%) CR patients obtained a DR, while only three of 11 (27%) R ones did (P = 0.027).

CR was a significant prognostic factor for the achievement of a DR. Moreover, we observed a trend for DR patients to obtain a subsequent SR.