Evaluation of Ruxolitinib Combined with AIEOP-BFM 2017 Chemotherapy in Pediatric Acute Lymphoblastic Leukemia with JAK/STAT Pathway Activation

The primary objective of this study is to compare the rate of minimal residual disease (MRD) negativity at time point 2 (TP2) in patients receiving **ruxolitinib** combined with Consol. IB extension to that in an appropriate external control group. This is clinically relevant as achieving MRD negativity is a critical prognostic factor in the treatment of children with acute lymphoblastic leukemia (ALL), particularly those with confirmed activation of the JAK/STAT pathway.

Secondary objectives include:

• Comparing the change in absolute MRD count between time points 1 (TP1) and TP2 in the ruxolitinib + Consol. IB extension group to that in an appropriate external control group.
• Evaluating the safety and tolerability of the ruxolitinib + Consol. IB extension regimen compared to an appropriate external control group.

The clinical trial focuses on participants diagnosed with **acute lymphoblastic leukemia** (ALL), specifically targeting a vulnerable population that includes both male and female subjects. The study encompasses individuals within the pediatric age range, as indicated by the age category code provided. Participants were selected based on specific genetic markers that activate the JAK-STAT pathway, such as CRLF2, JAK2, EPOR, or CRLF2 expression on leukemic cells. The trial population also includes those stratified as early high risk due to factors like lack of complete remission by day 33, certain genetic rearrangements, or specific minimal residual disease (MRD) levels. The sponsor has not provided the total number of participants involved in the study. Lifestyle considerations such as diet, physical activity, or habits are not specified in the available data.

The clinical trial is designed to evaluate the efficacy and safety of **ruxolitinib** in combination with standard chemotherapy protocols for children diagnosed with **acute lymphoblastic leukemia** (ALL) and confirmed activation of the JAK/STAT pathway. This is a single-arm, interventional study, categorized as a Phase II clinical trial. The trial is expected to run from April 2021 to May 2029, with the primary objective of comparing the rate of minimal residual disease (MRD) negativity at a specific time point (TP2) in patients receiving the combination therapy against an appropriate external control.

The trial design involves a series of structured visits, beginning with an inclusion (screening) visit to assess eligibility based on criteria such as newly diagnosed ALL, specific genetic lesions, and stratification as early high risk. Participants will undergo regular follow-up visits to monitor treatment response, adverse events, and overall health status. The end-of-study visit will conclude the participant's involvement, summarizing the outcomes and any long-term effects observed.

Participants are expected to be involved in the study for the duration of their treatment protocol, which varies depending on the specific chemotherapy regimen and individual response. The maximum treatment period for the investigational product, **ruxolitinib**, is 28 days. Conditions that may lead to early termination from the study include significant adverse events, withdrawal of consent, or any medical condition that contraindicates continued participation.

The trial will utilize a range of antineoplastic agents, including **methotrexate disodium**, **cytarabine**, **ifosfamide**, **vincristine sulfate**, and others, administered through various routes such as intravenous, oral, and intrathecal. The study will closely monitor the frequency and grading of adverse events, as well as the incidence of treatment-related adverse and severe adverse events, to ensure participant safety and gather comprehensive data on the treatment's impact.

The clinical trial involves the administration of several experimental medications, each with specific pharmaceutical forms, dosages, routes, and frequencies of administration. **Methotrexate Disodium** is provided as a solution for injection, administered via intrathecal use. The maximum daily dose is 12 mg, with a total dose not exceeding 228 mg over a treatment period of 19 days. **Cytarabine** is available as a solution for injection, administered intravenously. The maximum daily dose is 2000 mg/m², with a total dose of 14400 mg/m² over 35 days. **Ifosfamide** is provided as a powder for solution for infusion, administered intravenously, with a maximum daily dose of 800 mg/m² and a total dose of 4000 mg/m² over 3 days.

**Ruxolitinib** is administered orally in tablet form, with a maximum daily dose of 80 mg/m² and a total dose of 2240 mg/m² over 28 days. **Vindesine Sulfate** is a powder for solution for injection, administered intravenously, with a maximum daily dose of 3 mg/m² and a total dose of 6 mg/m² over 2 days. **Dexamethasone Phosphate** is provided as a solution for injection/infusion, administered intravenously, with a maximum daily dose of 20 mg/m² and a total dose of 868.75 mg/m² over 91 days.

**Vincristine Sulfate** is a solution for injection, administered intravenously, with a maximum daily dose of 2 mg and a total dose of 20 mg over 10 days. **Etoposide** is a concentrate for solution for infusion, administered intravenously, with a maximum daily dose of 100 mg/m² and a total dose of 500 mg/m² over 3 days. **Cyclophosphamide** is a powder for solution for injection, administered intravenously, with a maximum daily dose of 1000 mg/m² and a total dose of 4500 mg/m² over 8 days.

**Asparaginase** is provided as a powder for solution for injection, administered intravenously, with a maximum daily dose of 20000 IU and a total dose of 980000 IU over 49 days. **Daunorubicin** is a concentrate for solution for infusion, administered intravenously, with a maximum daily dose of 30 mg/m² and a total dose of 30 mg/m² over 1 day. **Mercaptopurine** is administered orally in tablet form, with a maximum daily dose of 60 mg/m² and a total dose of 30240 mg/m² over 630 days.

**Pegaspargase** is a solution for injection/infusion, administered intravenously, with a maximum daily dose of 3750 IU and a total dose of 17500 IU over 7 days. **Dexamethasone** is administered orally in tablet form, with a maximum daily dose of 20 mg/m² and a total dose of 868.75 mg/m² over 91 days. **Doxorubicin Hydrochloride** is a concentrate for solution for infusion, administered intravenously, with a maximum daily dose of 30 mg/m² and a total dose of 180 mg/m² over 6 days.

**Tioguanine** is administered orally in tablet form, with a maximum daily dose of 60 mg/m² and a total dose of 2520 mg/m² over 42 days. **Methotrexate** is available in multiple forms: as a tablet for oral administration with a maximum daily dose of 20 mg/m² and a total dose of 1600 mg/m² over 80 days, and as a concentrate for solution for infusion, administered intravenously, with a maximum daily dose of 5000 mg/m² and a total dose of 20000 mg/m² over 4 days.

The efficacy of the clinical trial will be assessed by evaluating the primary endpoint, which is the proportion of patients achieving **MRD(-)** (minimal residual disease negativity) at TP2. This endpoint is critical in determining the effectiveness of the treatment regimen involving ruxolitinib in combination with the AIEOP-BFM 2017 Poland or AIEOP-BFM 2017 standard of care chemotherapy in children with acute lymphoblastic leukemia (ALL) and confirmed activation of the JAK/STAT pathway. The assessment will involve measuring the MRD status at specific timepoints, with TP2 being a key milestone in the trial.

Secondary endpoints will include the frequency and grading of adverse events during the Consol. IB ext. phase, as well as the incidence of treatment-related adverse and severe adverse events. These parameters will be collected and analyzed to provide a comprehensive understanding of the safety profile of the treatment. The trial is designed as a single-arm interventional study, and the data collected will be compared to appropriate external controls to evaluate the efficacy and safety of the treatment regimen.