Objective: Report outcomes from the multi-year extension to the 52-week open-label InfusON study (NCT02339064)¹ of continuous subcutaneous apomorphine infusion (CSAI).

Background: The US phase 3 InfusON study supported long-term clinical utility of CSAI for reducing Parkinson disease (PD) motor fluctuations.  GOOD ON time improved by 3.1±3.4 h/day at week 12 and 3.7±3.3 h/day at week 52, with corresponding improvement in patient-rated quality of life (PDQ-39: −4.5±10.6; −3.3±11.3) and function (UPDRS Part II −2.8±5.4; −1.4±4.6). An optional study Extension Period ended August 2025, following FDA approval of CSAI (February 2025).

Method: The open-label study enrolled individuals with PD experiencing ≥3h/day of OFF time despite optimized levodopa and current/prior use of ≥1 adjunctive PD therapy. CSAI was titrated to optimal efficacy and tolerability (but not exceeding 8 mg/h or 150 mg/day). Participants completing the 52‑week Maintenance Period could continue in an Extension Period until market availability. Results are summarized descriptively for observed cases.

Results: Of 99 treated participants, 48 completed the Maintenance Period, and 45 (93.8%) entered the Extension Period. At study close, the total (all phases) median [Q1, Q3] treatment duration was 11 [3, 32] months (maximum 9.3 years), with 49, 30, 24, 15, and 11 participants completing 1, 2, 3, 4, and 5 years of treatment. Two completed ≥8 years before transitioning to marketed product.  Median [Q1, Q3] infusion rates were 3.95 [2.91, 4.77] mg/h during the Maintenance Period (n=85) and 4.22 [3.58, 5.30] mg/h during the Extension Period (n=44). At long‑term follow‑up, reductions in mean±SD daily OFF time were maintained at the 2‑year visit (-2.8±3.1 h), 3‑year visit (‑3.5±4.0 h), 4‑year visit (‑3.3±4.4 h), and 5‑year visit (-2.8±4.1 h). Corresponding increases in Good ON time were also sustained at the 2‑year (3.1±3.4 h), 3‑year (3.6±3.4 h), 4‑year (3.7±4.4 h), and 5‑year (2.9±3.5 h) visits. Adverse events ≥5% and at least possibly related to treatment reported at any time during the ≥8-year Extension Period included infusion site nodules 46.7%, dyskinesia 20.0%, hallucination 17.8%, anxiety 8.9%, somnolence 6.7%, orthostatic hypotension 6.7%, and fall 6.7%. No new safety signals emerged.

Conclusion: These findings allow for long-term safety and efficacy assessment of adjunctive CSAI in the US.

References: 1. Isaacson et al. J Parkinsons Dis. 2025;15(2):361-373.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/continuous-subcutaneous-apomorphine-infusion-in-parkinson-disease-final-data-from-the-multi-year-infuson-open-label-extension-study/