Objective: To evaluate responder rates for Good ON time and OFF time with IPX203 using PD diary data from the RISE-PD trial, including comparisons by study entry motor fluctuation severity.

Background: IPX203 is a new modified release formulation of levodopa/carbidopa (LD/CD) designed to improve LD delivery and increase duration of benefit. Understanding response patterns across patient subgroups can contribute to more individualized treatment planning.

Method: Responder analyses were performed at multiple study visits in RISE-PD participants achieving ≥1 hour improvement in Good ON time or OFF time. End of IR optimization (visit 2) served as the primary reference point. Additional scenarios evaluated responses during the IR optimization period (visit 1–2), the open label IPX203 conversion period (visit 2–4), and using study entry (visit 1) as an alternative reference point. Responder rates were assessed overall and by motor fluctuation severity at study entry, defined here as MODERATE (visit 1 OFF time 2.5–5 hours; n=209) and SEVERE (visit 1 OFF time ≥5 hours; n=415). The average number of patients needed to be treated with IPX203 to observe one responder at study end (visit 7) was calculated.

Results: During IR optimization, “severe fluctuators” showed higher response rates (over 50%) than “moderate fluctuators” (17–30%). With conversion to IPX203 after IR optimization (visit 2–4), more than 50% of patients achieved a clinically meaningful ≥1 hour improvement, regardless of severity, with response rates sustained through visit 7. Across IR optimization and conversion to IPX203 (visit 1–4), higher responder rates were observed in severe versus moderate fluctuators. The average number of patients needed to be treated with IPX203 to obtain one responder at visit 7 ranged from 1.8 to 1.9 with visit 2 as reference (post IR optimization). When visit 1 was used as reference, values ranged from 1.4 (severe) to 1.8 (moderate).

Conclusion: Following conversion to IPX203 after IR optimization, more than half of patients achieved sustained, clinically meaningful improvement in Good ON time or OFF time, regardless of baseline fluctuation severity. Patients with severe fluctuations demonstrated greater response during IR optimization, but response rates after conversion to IPX203 were similarly high across severity groups. These results demonstrate the robust clinical effectiveness of IPX203 across fluctuation severity levels.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/ipx203-achieves-high-responder-rates-independent-of-fluctuation-severity-insights-from-rise-pd/