Patrys (ASX:PAB) Moves Its Intravenous Delirium Candidate RLS-2202 Into Cohort 2 of Phase 1a

Sonal Goyal

22 October 2026 12:09 PM AEDT

Patrys (ASX:PAB) Moves Its Intravenous Delirium Candidate RLS-2202 Into Cohort 2 of Phase 1a

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Key Highlights

All four participants in Cohort 1 of the RLS-2202 Phase 1a trial completed dosing and the protocol-defined safety observation period.
The Safety Review Committee found an acceptable safety and tolerability profile at the initial dose level and recommended progression to Cohort 2.
Cohort 2 will enrol twelve healthy volunteers in a cross-over design with a four-day washout between oral quetiapine and RLS-2202.
Patrys expects dosing of the final participant to be completed in Q4 2026.

Patrys Limited (ASX:PAB) has advanced its Phase 1a clinical trial of RLS-2202 into a second cohort after a Safety Review Committee (SRC) evaluated the data generated in the first. RLS-2202 is the company's injectable therapy for delirium, and the study is being run in healthy volunteers.

The committee examined safety, tolerability and pharmacokinetic information from Cohort 1 and recommended that the study move forward at a dose set under its predefined dose-escalation design. Recruitment for Cohort 2 is expected to commence shortly, and the company has stated that it remains on track to complete dosing in the fourth quarter of 2026.

Cohort 1 Completes and the Committee Signs Off

All four participants in the first cohort completed dosing and went through the protocol-defined safety observation period. After reviewing the available safety, tolerability and pharmacokinetic data, the SRC concluded that RLS-2202 showed an acceptable safety and tolerability profile at the initial dose level.

Chief Executive Officer Dr Samantha South described the completion of Cohort 1 as a key milestone for the RLS-2202 program. She noted that exploratory results from the cohort had already informed the dose chosen for the next stage. The company said participant safety and data quality remain its highest priorities, and that it will continue to issue updates as further milestones are reached.

Why the Study Is a Bridging Exercise

Patrys describes the Phase 1a study as a technically well-controlled bridging study. Quetiapine carries a well-established safety profile as an oral drug, but RLS-2202 is a new intravenous formulation. The company points out that intravenous delivery can produce a different exposure profile, for example a higher peak concentration and faster onset, with no first-pass metabolism.

The trial is therefore designed to show how exposure to RLS-2202 compares with exposure to oral quetiapine. If the comparison holds, the existing oral safety and efficacy data could be used to support the intravenous formulation without repeating the full development program.

The company states that the study does not introduce a new active molecule, yet its results are described as critical to the progression of the program. The pharmacokinetic and safety data are intended to support the bridging of established oral experience to the intravenous form, to inform the design of the next clinical study, and to provide a foundation for future engagement with regulators, including the U.S. Food and Drug Administration.

Cohort 2 Design and Scheduled Milestones

Cohort 2 uses a cross-over design. Twelve healthy volunteers will each receive both the reference oral quetiapine formulation and RLS-2202, with the two administrations separated by a four-day washout period. The company says this structure is intended to reduce the influence of individual differences in metabolism on how the results are interpreted, giving a clearer picture of the pharmacokinetic profile of intravenous RLS-2202.

Patrys also says a successful study has the potential to materially reduce the development burden of establishing a new intravenous treatment option for delirium, which it characterises as a condition that can develop rapidly, is associated with serious consequences, and currently has limited options for rapid alleviation.

The company has set out a sequence of steps that follows initiation of Cohort 2. In October 2026, GMP-grade RLS-2202 for Cohort 2 dosing is due to be released and delivered to CMAX. During the fourth quarter of 2026, screening and enrolment of Cohort 2 participants is to be completed, and the bioanalytical assay is to undergo GLP validation in the range required for Cohort 2 analysis.

Cohort 2 dosing is also expected to commence and finish within the same quarter. Patrys reiterated that it intends to dose the final participant in Cohort 2 on that timetable and will report further as clinical milestones are achieved and study data become available.

Where the Study Stands Now

At this point, Patrys has a completed first cohort of four participants, a committee recommendation to proceed, and a defined dose for the next stage. The next cohort expands the participant number to twelve and introduces the direct comparison between the oral and intravenous formulations, with delivery of the clinical-grade material to the trial site scheduled for October 2026 and dosing set for the fourth quarter. The company has not yet reported any Cohort 2 results.

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