Interim Analysis of Treatment Satisfaction from a Prospective Phase 4 Study in Adult Immune Thrombocytopenia (ITP) Subjects after Switching from Eltrombopag or Romiplostim to Avatrombopag

Background:

Recently, the Thrombopoietin-Receptor Agonist (TPO-RA) Patient experience survey (TRAPeze) determined that the characteristics which influence preference towards TPO-RA treatments the most were the method of administration and drug-food interactions. Specifically, participants were more likely to select an oral tablet over a subcutaneous injection and a treatment without food restrictions rather than one with food restrictions (McDonald V, et al, 2021).

A majority of patients in a real-world analysis who switched from eltrombopag (ELT) or romiplostim (ROMI) to avatrombopag (AVA) did so due to perceived convenience benefits (Al-Samkari H, et al, 2022). The ongoing AVA-ITP-401 prospective interventional study is evaluating treatment satisfaction and on-therapy convenience in patients immediately switching to AVA from either ELT or ROMI and aims to provide valuable patient-reported outcomes. Safety and platelet count (PC) response to AVA following a switch from the other two TPO-RAs are also being evaluated. In a separate abstract submission, the mean/median PCs are reported to either be improved or maintained with AVA treatment over 90 days.

Methods:

This is an interim analysis of a prospective, multi-center, open-label Phase 4 study being conducted in the US (NCT04638829) since March 2021. Subjects who have been receiving ELT or ROMI for ≥90 days prior to study entry are enrolled and immediately switched to AVA at a starting dose of 20 mg daily.

Key inclusion criteria: age ≥18 years; subjects have been undergoing treatment for primary ITP with ELT or ROMI for ≥90 days prior to the screening visit; subjects have had a previous response to either ELT or ROMI.

The primary endpoint is occurrence of adverse events and serious adverse events.

A key secondary endpoint is the change from baseline in each of the 4 domains of the self-administered Treatment Satisfaction Medication Questionnaire (TSQM) Version 1.4 (convenience, global satisfaction, effectiveness, and side effects) to Day 90 (D90) or End of Study (EOS). An increase in domain mean score indicates an increased patient preference to a given therapy in that domain.

Clinic Visits were mandated per protocol at Days 15 (D15), 30 (D30), 60 (D60), and 90/End of Study (D90/EOS) with PCs obtained at each timepoint. The TSQM was assessed at baseline (BL), D30, and D90/EOS.

Results:

As of April 1, 2023, 51 patients were screened with 47 enrolled. 35 completed the study, 3 dropped out, and 6 are on-going.

The mean age at enrollment was 58 years, the median (min,max) time since ITP diagnosis was 2.88 years (0.2,31.0), 60% were female, 72% were Caucasian, and 11% had a previous history of splenectomy.

62% of patients were switched to AVA from ELT (median prior treatment duration 42 weeks (range 12 - 442); median daily dose 50 mg) and 38% from ROMI (median prior treatment duration 81 weeks (range 12 - 468); median weekly dose ≤3 µg).

Safety results will be reported when the study is complete.

TSQM individual domain BL, D30, and D90/EOS mean values and mean percent change from BL following the switch from either ELT or ROMI to AVA are summarized in Table 1.

In the Total Population, scores at BL in all four domains were generally high reflecting patient satisfaction to their prior therapy. Following the switch to AVA, however, there was measurable improvement in satisfaction across all domains-most pronounced in the effectiveness, convenience, and global satisfaction domains. This improvement began at D30 and was maintained through D90/EOS.

The increase in patient-reported satisfaction was greater in ELT-switchers than with ROMI-switchers; however, improvement in satisfaction was observed by EOS across all four domains in the ROMI-switching population as well.

Summary/Conclusion:

Despite high patient satisfaction scores at BL from prior therapy (ELT or ROMI), patients reported higher satisfaction following a switch to AVA across all domains of the TSQM (effectiveness, side effects, convenience, and global satisfaction) over 90 days. In a population of patients who were generally responding to TPO-RAs prior to a switch to AVA, mean/median PCs were also either improved or maintained with AVA treatment for the duration of the study (reported in a separate abstract submission), suggesting that some patients may experience sustained effectiveness paired with enhanced overall treatment satisfaction when switching from ELT or ROMI.