Key Highlights

• Patrys Limited (ASX:PAB) has dosed the first participants in the Phase 1a clinical trial of RLS-2202, its proprietary intravenous (IV) formulation of the established antipsychotic medicine quetiapine.

• The ASX-listed biotech said on 23 September 2026 that dosing had started in Cohort 1 of the study, which is being run in healthy volunteers.

• The milestone marks the start of human testing for RLS-2202, which Patrys is developing as a potential IV treatment option for delirium in acute care settings.

• As a Phase 1a study, the trial is an early-stage safety study.

Patrys Limited (ASX:PAB) has dosed the first participants in the Phase 1a clinical trial of RLS-2202, its proprietary intravenous (IV) formulation of the established antipsychotic medicine quetiapine. The ASX-listed biotech said on 23 September 2026 that dosing had started in Cohort 1 of the study, which is being run in healthy volunteers.

The milestone marks the start of human testing for RLS-2202, which Patrys is developing as a potential IV treatment option for delirium in acute care settings. As a Phase 1a study, the trial is an early-stage safety study. Its primary objective is to assess safety and tolerability, and it is not designed to show whether the drug works in patients with delirium. The company said an independent Safety Review Committee meeting is scheduled for October 2026 ahead of potential progression to Cohort 2.

What was announced

According to the announcement, the Phase 1a study is a bridging trial designed to evaluate the safety, tolerability and pharmacokinetic (PK) profile of RLS-2202 in healthy adult volunteers. Pharmacokinetics describes how a drug is absorbed, distributed and cleared by the body.

In Cohort 1, each participant will receive both the reference oral formulation of quetiapine and RLS-2202, separated by a four-day washout period. The study uses a dose-escalation design, and progression between the two cohorts is subject to review by the independent Safety Review Committee in line with the study protocol.

Secondary objectives include evaluation of the drug's PK profile and dose levels to support later clinical development. Patrys said the study will generate the data required to inform dose selection and the next stage of the program.

Why a bridging study matters

Quetiapine has an extensive history of oral use in treating schizophrenia and bipolar disorder. Patrys is developing RLS-2202 as an IV formulation with the stated objective of providing an alternate, faster and safer route of administration for patients with delirium in acute care settings. Those are the company's development goals rather than proven outcomes.

The company said the Phase 1a study is designed to assess whether IV administration of RLS-2202 shows any clinically meaningful differences from the established profile of oral quetiapine. It will also help identify the dose range and PK profile to guide future trials evaluating efficacy in the target patient population.

Patrys added that the results are expected to inform regulatory discussions about the extent to which the established safety information for oral quetiapine may be relevant to the RLS-2202 program. Subject to positive results, the company said this could support a potential pathway to regulatory approval. That pathway remains some distance away, with efficacy trials in patients still to be designed and conducted.

What the CEO said

Chief Executive Officer Dr Samantha South said: "We are delighted to announce the dosing of the first participants in our Phase 1a clinical trial. This is a major milestone for RLS-2202 and for Patrys."

She added: "We have now moved from developing the formulation and preparing for the clinic to generating human clinical data. We look forward to evaluating the clinical data, as these results will inform the strategy for advancement into later-stage development."

Manufacturing update

Alongside the dosing news, Patrys said it has completed GMP Manufacturing and filling of the RLS-2202 clinical trial material required for Cohort 2. GMP, or good manufacturing practice, refers to the quality standards required for medicines used in humans.

The manufactured product is now undergoing quality control testing before it can be released for clinical use. Patrys said that, subject to successful completion of this testing and release of the material, it expects to have sufficient trial material to support dosing of Cohort 2 and associated planned activities.

Company background

Patrys describes itself as a clinical-stage company developing an injectable therapy for delirium alongside a deoxymab platform targeting immune-mediated inflammatory diseases. The delirium program came to the company through its Acquisition of Reliis, which Biotech Dispatch reported was completed in January 2026. At that time, the injectable quetiapine program was referred to as RLS-2201; the company now refers to the program in its trial as RLS-2202.

The Reliis deal was accompanied by board changes, with Leanne Kite and Dino Cercarelli appointed as non-executive directors, according to the same report. Since then, Patrys has worked through formulation, manufacturing and trial preparation to reach first dosing.

For investors following ASX shares in the healthcare and biotech sector, the transition from preclinical and formulation work into human studies is often a notable point in a small company's development. However, the value of that step depends on what the data ultimately show.

What comes next

Patrys set out the following key milestones for the RLS-2202 Phase 1a study:

• October 2026: the independent Safety Review Committee is scheduled to review available Cohort 1 safety data before progression to Cohort 2.

• Q4 CY26: subject to a satisfactory safety review and successful quality control testing and release of Cohort 2 clinical material, Patrys expects to commence dosing of Cohort 2.

• Q4 CY26: Patrys said it remains on track to complete dosing of the final participant in Cohort 2.

The company said it intends to provide further updates as key clinical milestones are achieved and data from the study become available.

Risks and considerations

The Phase 1a trial is at an early stage, and several conditions sit between today's announcement and completion. Progression to Cohort 2 depends on a satisfactory safety review, and dosing that cohort depends on the new batch of trial material passing quality control. Any safety signal, manufacturing issue or delay could affect the company's stated timetable.

Even a successful Phase 1a result would only establish early safety and PK information in healthy volunteers. It would not demonstrate efficacy in delirium, which would require further trials in the target patient population. Regulators may also take a different view from the company on how much existing oral quetiapine safety data can be relied on. Patrys' announcement includes forward-looking statements that the company cautions are subject to assumptions and contingencies and are not a guarantee of future performance.

The bottom line

Patrys has moved RLS-2202 into the clinic, with the first healthy volunteers dosed in a Phase 1a safety and PK study in September 2026. The October safety review and Cohort 2 dosing in the December quarter are the next checkpoints, and the data will shape whether and how the IV quetiapine program advances into efficacy testing.