PO028 | SUSTAINED RESPONSE OFF TREATMENT IN ITP PATIENTS TREATED WITH TPO-RA: A SINGLE-CENTER EXPERIENCE

A. Baffioni¹, C. Giubbilei¹, G. Giustini¹, A.M. Vannucchi², V. Carrai³ | ¹SOD Ematologia, Università degli studi di Firenze, Italy; ²Center for Innovation and Research in Myeloproliferative Neoplasms, SOD Ematologia, Azienda Ospedaliera Universitaria Careggi, Università degli studi di Firenze, Italy; ³SOD Ematologia, Dipartimento di Oncologia, Azienda Ospedaliera Universitaria Careggi. Firenze, Italy

Background and Aims. The introduction of thrombopoietin receptor agonists (TPO-RAs) has significantly improved response rates in patients with immune thrombocytopenia (ITP). In a subset of patients, a sustained response can be achieved despite progressive dose reduction and even after treatment discontinuation, defined as sustained response off treatment (SROT). We analyzed patients from our center who achieved SROT, evaluating response duration, tapering strategies, and relapse rates, with the aim of contributing to process standardization.
Methods. Seventeen patients (9 males, 8 females) were included, with a median age at diagnosis of 63 years (range 21–73). Before TPO-RA initiation, 12/17 patients (70.6%) had received one prior treatment line, 3/17 (17.6%) two lines, and 2/17 (11.8%) ≥3 lines. TPO-RAs were started within 3 months from diagnosis in 2/17 patients, during the persistent phase in 5/17, and in the chronic phase in 10/17. Six patients received eltrombopag, ten romiplostim, and one avatrombopag.
Results. Median duration of TPO-RA therapy was 24 months (range 3–79), with a median peak platelet count of 308×10⁹/L. Tapering was performed over a median of 12 months; median platelet count at tapering initiation was 223.5×10⁹/L, with a nadir of 119×10⁹/L during dose reduction. In 2/17 patients, treatment was discontinued without tapering due to adverse events; both maintained SROT for more than 10 years. Median dose at discontinuation was 25 mg/week for eltrombopag, 0.065 mL/week for romiplostim, and 10 mg/week for avatrombopag. Median platelet count at discontinuation was 139×10⁹/L. Median follow-up after discontinuation was 53 months. Relapse occurred in 4/17 patients: two were successfully treated with corticosteroids, while two resumed TPO-RA therapy; one of these regained SROT after a second tapering attempt, while the other remains on treatment.
Conclusions. SROT is an achievable goal in a subset of ITP patients treated with TPO-RAs, with relevant clinical and psychological impact, although relapse may occur in a minority of cases. Our monocentric experience is consistent with available literature and supports the need for standardized tapering strategies. Data on avatrombopag remain limited, and further studies are warranted to identify predictive factors for SROT