Cleo Diagnostics Completes 514 Sample Collection for Pivotal Ovarian Cancer Trial

Cleo Diagnostics completes sample collection for pivotal U.S. ovarian cancer test trial

Cleo Diagnostics has achieved a key milestone in its Cleo Diagnostics Ovarian Cancer Trial, with 514 blood samples collected from its pivotal U.S. clinical study. The biotech company enrolled 624 women across 19 clinical trial sites, surpassing its minimum recruitment target of 500 participants and moving the programme into its final technical and regulatory phase ahead of FDA submission.

The trial was designed to demonstrate the performance of the company’s Pre-Surgical Ovarian Cancer Test and benchmark it against existing tools used to assess ovarian malignancy risk. Completing sample collection removes a major execution risk and positions Cleo to advance toward potential commercialisation of its diagnostic platform.

What is a Pre-Surgical Ovarian Cancer Test?

Cleo’s Pre-Surgical Ovarian Cancer Test is designed for women with an adnexal mass (a growth near the ovary or fallopian tube) who have surgery planned. The test aims to assess the risk of ovarian malignancy before surgical intervention, helping clinicians determine the appropriate surgical approach and specialist referral pathway.

The test is built around CXCL10, a proprietary biomarker that is produced at high levels by ovarian cancers but is largely absent in non-malignant disease. This differentiation offers a potential improvement over existing risk assessment methods, which can struggle to distinguish benign from malignant growths with sufficient accuracy. The test aims to provide clinicians with clearer pre-surgical triage information, reducing the likelihood of inappropriate surgical management or delayed specialist care.

By enabling more accurate risk stratification before surgery, the test addresses a clinical gap in ovarian cancer diagnosis where early and accurate detection significantly impacts patient outcomes. The commercial opportunity centres on surgical triage initially, with Cleo’s modular strategy designed to expand into recurrence monitoring, high-risk screening, and early-stage detection markets.

Trial execution and sample quality strategy

Cleo enrolled 624 women to achieve 514 usable samples, reflecting standard clinical trial practice designed to ensure a robust final dataset. The difference between enrolment and collected samples accounts for the natural lag between patient recruitment and sample collection, during which women may still be awaiting surgery or post-surgical diagnosis confirmation.

Not all enrolled patients ultimately yield complete blood samples and confirmed pathology suitable for inclusion in the final dataset. By recruiting beyond the 500-woman minimum target, Cleo applied a quality-focused approach that prioritises dataset integrity over nominal enrolment figures. This over-recruitment strategy is consistent with professional trial management and de-risks the quality of the final clinical evidence package.

Clinical Workflow

Blood samples were collected prior to surgery and stored under controlled conditions. Pathology information was subsequently captured following surgery and diagnosis, ensuring each sample is matched with confirmed clinical outcomes.

The samples represent a diverse U.S. population, strengthening the generalisability of the trial results and supporting regulatory requirements for FDA 510(k) submission.

Next steps toward FDA 510(k) submission

With sample collection complete, Cleo has outlined a four-step pathway to generate the clinical dataset required for FDA submission:

1. Pre-verification: Internal readiness activities to confirm that Cleo’s assay, kit components, and testing workflow perform as expected prior to formal validation and subsequent clinical sample testing.

2. Analytical validation: Formal demonstration that Cleo’s assay, kit components, and testing workflow perform consistently and reproducibly on the Ella™ platform, providing the technical foundation required to commence clinical sample testing.

3. Clinical sample testing: Testing of collected blood samples from the clinical trial in accordance with approved protocols to generate assay result data using the final test kit.

4. Clinical data analysis and validation: Statistical analysis of assay results against confirmed pathology outcomes to evaluate test performance metrics including sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV), generating the clinical evidence package required for FDA 510(k) submission.

Testing will occur on the Ella™ platform, with performance metrics designed to demonstrate the test’s clinical utility in pre-surgical ovarian cancer risk assessment. The timeline for these activities is dependent upon manufacturing scheduling, which will be released following execution of a binding agreement with Cleo’s manufacturing partner.

Manufacturing agreement in final stages

Cleo is in final discussions to enter into a binding manufacturing agreement for test kit production. This follows the recent completion of biomarker panel optimisation, announced on 23 March 2026. Execution of this agreement triggers the next step in the pathway to formal clinical testing and represents the near-term catalyst investors should monitor.

Securing a manufacturing partner removes a critical dependency risk and enables Cleo to move from sample collection into the active testing and validation phase. The company has stated that a timeline update will be released to the market following agreement execution.

What this means for Cleo’s ovarian cancer diagnostic pathway

Cleo has now de-risked a significant portion of its clinical programme, with sample collection complete, a clear regulatory pathway defined, and manufacturing partnership discussions in final stages. The 514 samples in storage represent over 15 years of scientific research and development at the Hudson Institute of Medical Research, underpinned by a worldwide exclusive licence to commercialise the intellectual property.

The test addresses a clinical unmet need in ovarian cancer detection, where early and accurate diagnosis significantly shifts survivability outcomes. Cleo’s modular commercial strategy is designed to address multiple detection markets, starting with surgical triage and expanding into recurrence monitoring, high-risk screening, and early-stage detection.

With FDA submission now dependent on manufacturing execution and validation milestones rather than clinical recruitment risk, Cleo has transitioned from the enrolment phase into the final technical and regulatory execution phase. Investors have clear visibility on the pathway ahead, with manufacturing agreement execution and subsequent validation milestones representing the next key catalysts.

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