Evaluation of Gaxilose Efficacy for Diagnosing Hypolactasia in Pediatric Patients with Lactose Intolerance Symptoms

The primary objective of this study is to confirm the **cut-off point** proposed in the Phase I study, specifically 19.18 mg of xylose in 5 hours of urine accumulation. This objective aims to determine if this cut-off point can effectively classify pediatric patients as hypolactasic or normolactasic when compared with the definitive diagnosis according to routine clinical practice. This is clinically relevant as it seeks to validate a diagnostic tool for **lactose intolerance** in children, potentially improving diagnostic accuracy and patient management.

Secondary objectives include:

• Exploration of different cut-off points of xylose to classify pediatric patients as hypolactasic or normolactasic.
• Assessing the possibility of shortening urine collection to 4 hours to streamline the test in this pediatric population and identify the cut-off point.
• Evaluating the safety and tolerability of LacTEST 0.45 g in this pediatric population.

The clinical trial involves a study population of **children** aged between 5 and 11 years, comprising both male and female participants. The trial focuses on individuals exhibiting symptoms of **lactose intolerance**. The total number of participants has not been disclosed by the sponsor. Participants were selected based on their age and symptomatic presentation, with the requirement that their parent(s) or legal guardian(s) are willing and able to comply with all scheduled visits, treatment plans, laboratory tests, and other study procedures. The trial does not involve a vulnerable population, and no specific lifestyle considerations such as diet or physical activity have been highlighted as part of the study criteria.

The clinical trial is designed as a **randomized**, **double-blind**, and **controlled** study to evaluate the efficacy of LacTEST 0.45 g for diagnosing **lactose intolerance** in children aged 5 to 11 years. The trial will commence on July 14, 2025, and is expected to conclude by June 1, 2026. The primary objective is to confirm the cut-off point of 19.18 mg of xylose in 5 hours of urine accumulation, as established in a previous Phase I study, to classify pediatric patients as hypolactasic or normolactasic. The trial will assess the diagnostic performance of LacTEST, including sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), using the proposed cut-off point.

Participants will undergo a series of study visits, beginning with an inclusion (screening) visit to determine eligibility based on criteria such as age, symptoms of lactose intolerance, and the ability of the participant's parent(s) or legal guardian(s) to comply with study procedures. Follow-up visits will be scheduled to monitor the diagnostic performance of LacTEST and to collect urine samples for analysis. The end-of-study visit will conclude the participant's involvement, with a comprehensive assessment of the diagnostic outcomes and any adverse events (AEs) related to the investigational product.

The expected length of participant involvement is approximately one year, aligning with the overall trial duration. Conditions that may lead to early termination from the study include non-compliance with study procedures, withdrawal of consent by the participant's parent(s) or legal guardian(s), or any adverse events that compromise the safety of the participant. The study is classified as a low-intervention trial, as the investigational medicinal product is authorized and used according to its marketing authorization, posing no additional risk or burden compared to normal clinical practice.

The clinical trial involves the use of **LacTEST**, a diagnostic agent formulated as a powder for oral solution. The active substance in LacTEST is **gaxilose**, a chemical compound used to evaluate the presence of hypolactasia in pediatric patients. The pharmaceutical form of LacTEST is an oral solution, and it is administered via oral route. The dosage for this trial is 0.45 grams, with a maximum daily dose and total dose of 0.45 grams. The treatment period is limited to a single day, ensuring that the administration aligns with the study's objective of diagnosing lactose intolerance symptoms in children aged 5 to 11 years. The product is manufactured by VENTER PHARMA S.L. and is authorized for use in Spain under the marketing authorization number 75797.

In this study, no non-experimental treatments such as standard-of-care therapy, placebo, or comparator treatments are utilized. The focus is solely on the administration of LacTEST to determine its efficacy in diagnosing hypolactasia. Participant compliance is monitored through the collection of urine samples over a 5-hour period to measure the excretion of xylose, which serves as a biomarker for the diagnosis. The trial aims to confirm the cut-off point of 19.18 mg of xylose in urine, as established in a previous Phase I study, to classify patients accurately as hypolactasic or normolactasic.

The efficacy of LacTEST 0.45 g for diagnosing **hypolactasia** in children aged 5 to 11 years with symptoms of lactose intolerance will be assessed in this clinical trial. The primary endpoint is the diagnostic performance, including sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), of LacTEST 0.45 g using a proposed cut-off point of 19.18 mg of xylose in 5 hours of urine accumulation. This cut-off point aims to classify pediatric patients as hypolactasic or normolactasic when compared with the definitive diagnosis according to routine clinical practice.

Secondary endpoints include evaluating the diagnostic performance of different cut-off points of xylose to classify patients, assessing the performance of shortening urine collection to 4 hours using the best cut-off, and recording the number and percentage of adverse events (AEs) and their relationship with LacTEST 0.45 g in this pediatric population. The trial will involve collecting and analyzing urine samples to measure xylose levels, with the primary focus on confirming the efficacy of the proposed cut-off point in a real-world setting.