Efficacy and Safety of Mitapivat in Pediatric Patients with Pyruvate Kinase Deficiency Undergoing Regular Transfusions: A Phase 3 Randomized, Double-Blind, Placebo-Controlled Trial

The primary objective of this Phase 3, multicenter, randomized, double-blind, placebo-controlled study is to evaluate the **efficacy** of **mitapivat** in reducing the transfusion burden in pediatric subjects with **Pyruvate Kinase Deficiency** who are regularly transfused. This objective is clinically relevant as it aims to address the significant transfusion requirements in this patient population, potentially improving their quality of life and reducing the risks associated with frequent blood transfusions.

The clinical trial involves a total of **38 participants** diagnosed with **Pyruvate Kinase Deficiency**. The study population includes both male and female subjects, aged between 1 and less than 18 years, with a specific requirement for those aged 12 to 24 months to weigh a minimum of 7 kg. Participants were selected based on clinical laboratory confirmation of PK deficiency, characterized by the presence of at least two mutant alleles in the PKLR gene, including at least one missense mutation. The trial targets a vulnerable population, as it includes pediatric subjects who are regularly transfused, with a history of six to 26 transfusion episodes in the 52-week period prior to consent. Participants are required to have complete records of transfusion history and must be receiving folic acid supplementation as part of their routine clinical care. Lifestyle considerations include the requirement for female subjects who have reached menarche or breast development in Tanner Stage 2 to abstain from sexual activities that may induce pregnancy or to use two forms of contraception during the study period. The trial aims to assess the efficacy of mitapivat treatment compared to placebo in reducing transfusion burden among these pediatric subjects.

The clinical trial is a **randomized**, **double-blind**, **placebo-controlled** study designed to evaluate the efficacy and safety of **mitapivat** in pediatric subjects with **pyruvate kinase deficiency** who are regularly transfused. The trial is structured in two phases: an initial double-blind period followed by a 5-year open-label extension. The primary objective is to assess the reduction in transfusion burden, with the primary endpoint being a transfusion reduction response defined as a ≥33% reduction in total red blood cell transfusion volume from Week 9 through Week 32 compared to historical data.

Participants will be involved in the study for an estimated duration extending to June 2029, with the recruitment phase having commenced in May 2022. The study includes several key visits: an initial screening visit to confirm eligibility, regular follow-up visits to monitor safety and efficacy, and an end-of-study visit to conclude participation. The inclusion criteria require participants to be aged 1 to <18 years, with clinical confirmation of pyruvate kinase deficiency and a history of 6 to 26 transfusion episodes in the year prior to consent. Participants must also be receiving folic acid supplementation and, if applicable, adhere to specific contraceptive measures.

Participant involvement may be terminated early if they fail to comply with study procedures, experience adverse effects that outweigh potential benefits, or withdraw consent. The investigational product, **mitapivat**, is administered orally in tablet or granule form, with a placebo used for control. The study is not classified as low intervention and is conducted under the sponsorship of Agios Pharmaceuticals. The trial aims to provide valuable insights into the management of pyruvate kinase deficiency in a pediatric population, with a focus on reducing the need for regular blood transfusions.

The clinical trial involves the administration of **MITAPIVAT**, a chemical compound with the active substance name **mitapivat**. The pharmaceutical form of MITAPIVAT is primarily a **tablet**, designed for **oral use**. The trial includes multiple formulations of MITAPIVAT, all produced by AGIOS PHARMACEUTICALS. The maximum treatment period for MITAPIVAT is specified as 1111 days, although specific dosage amounts are not provided. The chemical structure of MITAPIVAT is also known by the synonym N-(4-((4-(cyclopropylmethyl)-1-piperazinyl)carbonyl)phenyl)-8-quinolinesulfonamide, and it is identified by the sponsor product code AG-348.

In addition to the tablet form, MITAPIVAT is also available in **granules** for oral administration. This alternative formulation is intended to provide flexibility in dosing and administration, particularly for participants who may have difficulty swallowing tablets. The granules share the same active substance and chemical origin as the tablet form, ensuring consistency in the therapeutic effects across different formulations.

The study also includes a **placebo** group, which is a non-active comparator designed to match the MITAPIVAT treatment in appearance but without the active substance. The placebo is used to maintain the double-blind nature of the trial, ensuring that neither the participants nor the investigators are aware of the treatment assignments. This helps to objectively assess the efficacy and safety of MITAPIVAT by comparing outcomes between the active treatment and placebo groups.

The efficacy of the clinical trial will be assessed by evaluating the primary endpoint, which is the **Transfusion Reduction Response (TRR)**. This is defined as achieving a ≥33% reduction in the total red blood cell (RBC) transfusion volume from Week 9 through Week 32 of the Double-blind Period. The reduction will be normalized by weight and the actual study drug duration, compared with the historical transfusion volume standardized by weight and to 24 weeks. The trial aims to determine the efficacy of treatment with **mitapivat** compared with placebo in pediatric subjects with pyruvate kinase deficiency who are regularly transfused. The study will follow a randomized, double-blind, placebo-controlled design, ensuring that the assessment of efficacy is unbiased and scientifically robust.