PB0710 - Combination of all-trans retinoic acid resumes the sustained response of TPO-RA in ITP

Background: Sustain response off treatment (SROT) is the therapeutic goal for idiopathic thrombocytopenic purpura (ITP) patients treating by thrombopoietin receptor agonist (TPO-RA). Although the majority patients have therapeutic response during TPO-RA treatment, platelet counts may fluctuate in some cases. Researches showed that sustained and stable platelet response is one of the important conditions to achieve SROT.

Aims: All-trans retinoic acid (ATRA) has shown significant effects in treating ITP. Our study found that platelet fluctuation by TPO-RA treatment can be resumed by short term combined use of ATRA. In order to investigate whether Combination of all-trans retinoic acid resumes the sustained response of TPO-RA in ITP.

Methods: We enrolled 13 ITP patients from January 2023 to December 2023 in Nanfang hospital. Two of them were excluded because of insufficient treatment duration due to severe headache. Therefore, data from 11 patients were finally included. We defined platelet fluctuation as platelet numerical difference more than 100×109/L within one month. Oral dose of ATRA was 20mg once daily. Adverse events were monitored and assessed according to the Common Terminology Criteria for Adverse Events version 5.0 (CTCAE5.0).

Results: At baseline, the ratio of male vs. female was 2:9. The median age was 38 (range=22-64). The types of TPO-RAs used were: Eltrombopag 45.45% (5/11), Avatrombopag 36.36% (4/11), Hetrombopag 18.18% (2/11). The median time of ATRA treatment was 94 days (range=61-153). The efficiency rate of ATRA in resuming platelet response was 81.82% (9/11). Side-effects of ATRA in 11 patients were tolerable. The rate of dry and cracked lips was 18.18% (2/11). The rate of headache was 9.09% (1/11). The rate of hair loss was 9.09% (1/11). The rate of rash was 9.09% (1/11).

Conclusion(s): Our data shows that short-term treatment of ATRA in ITP during platelet fluctuation by TPO-RA may be effective and safe.