FDA Approves Bosulif for Pediatric Chronic Myelogenous Leukemia
Bosulif has received FDA approval for the treatment of pediatric chronic myelogenous leukemia, marking a significant advancement in pediatric oncology.
The FDA approved bosutinib (Bosulif) for pediatric patients with chronic myelogenous leukemia (CML) on September 26, 2023, based on the BCHILD trial demonstrating 76.2% major cytogenetic response in newly diagnosed patients aged 1 year and older.
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Key Takeaways
- FDA approved bosutinib (Bosulif) for pediatric CML on September 26, 2023, for patients aged 1 year and older with chronic phase Philadelphia chromosome-positive CML (FDA label).
- The BCHILD trial (NCT04258943) demonstrated 76.2% major cytogenetic response in newly diagnosed pediatric patients and 82.1% in resistant/intolerant patients (ClinicalTrials.gov).
- Recommended dosing is 300 mg/m²/day for newly diagnosed patients and 400 mg/m²/day for resistant/intolerant patients.
- Common adverse events include diarrhea, abdominal pain, vomiting, and hepatic dysfunction.
- Bosutinib joins imatinib, dasatinib, and nilotinib as approved TKIs for pediatric CML.
Drug Overview and Mechanism
Bosutinib is an oral dual Src/Abl tyrosine kinase inhibitor (TKI) designed to target the BCR-ABL1 fusion protein, the molecular hallmark of Philadelphia chromosome-positive CML. The drug binds to the ATP-binding site of the BCR-ABL1 tyrosine kinase, blocking downstream signaling pathways essential for malignant cell survival and proliferation.
The FDA first approved bosutinib in 2012 for adult patients with chronic, accelerated, or blast phase CML who were resistant or intolerant to prior therapy. This indication expanded in 2017 to include newly diagnosed chronic phase CML in adults. The pediatric approval on September 26, 2023, extended these indications to children aged 1 year and older.
When Was Bosulif Approved for Pediatric CML?
The FDA approved bosutinib (Bosulif) for pediatric CML on September 26, 2023. The approval covers pediatric patients aged 1 year and older with chronic phase Philadelphia chromosome-positive CML who are either newly diagnosed or have developed resistance or intolerance to prior therapy.
The approval was supported by data from the BCHILD trial (NCT04258943), a multicenter, nonrandomized, open-label study evaluating bosutinib in pediatric patients. The FDA also approved new capsule dosage forms of 50 mg and 100 mg specifically for pediatric use, allowing for body surface area-based dosing calculations.
Clinical Evidence: The BCHILD Trial
The BCHILD trial (NCT04258943) provided the clinical evidence supporting pediatric approval. This multicenter, open-label study evaluated bosutinib in two pediatric cohorts: newly diagnosed chronic phase CML and resistant/intolerant chronic phase CML.
| Response Endpoint | Newly Diagnosed (n=21) | Resistant/Intolerant (n=28) |
|---|---|---|
| Major Cytogenetic Response (MCyR) | 76.2% (95% CI: 52.8–91.8) | 82.1% (95% CI: 63.1–93.9) |
| Complete Cytogenetic Response (CCyR) | 71.4% (95% CI: 47.8–88.7) | 78.6% (95% CI: 59.0–91.7) |
| Major Molecular Response (MMR) | 28.6% (95% CI: 11.3–52.3) | 50.0% (95% CI: 30.6–69.4) |
| Median Follow-up Duration | 14.2 months | 23.2 months |
The trial demonstrated strong cytogenetic and molecular responses in both cohorts, supporting the approval for both treatment-naïve and previously treated pediatric patients.
Pediatric Dosing and Administration
The FDA established weight-based dosing recommendations specifically for pediatric patients. For newly diagnosed chronic phase CML, the recommended dose is 300 mg/m² orally once daily with food. For patients with resistant or intolerant disease, the recommended dose is 400 mg/m² orally once daily with food.
For pediatric patients unable to swallow capsules, the capsule contents can be mixed with applesauce or yogurt. This flexible administration option addresses a practical challenge in pediatric oncology where young children may have difficulty swallowing solid dosage forms.
Dose adjustments are required for hepatic impairment and for management of adverse reactions. Close monitoring of liver function tests and complete blood counts is recommended throughout treatment.
Safety Profile in Pediatric Patients
The safety profile of bosutinib in pediatric patients is generally consistent with that observed in adults, though with some differences in frequency and severity of certain adverse events.
Common adverse reactions occurring in at least 20% of pediatric patients include:
- Gastrointestinal: diarrhea, abdominal pain, vomiting, nausea, constipation, decreased appetite
- General: fatigue, headache
- Dermatologic: rash
- Hepatic: hepatic dysfunction, elevated transaminases
Myelosuppression including thrombocytopenia and neutropenia was observed, requiring monitoring of blood counts. Cardiac effects including fluid retention and cardiovascular events have been documented in adult studies and warrant monitoring in pediatric patients receiving long-term therapy.
How Does Bosutinib Compare to Other Pediatric TKIs?
Bosutinib now competes with three other tyrosine kinase inhibitors approved for pediatric CML: imatinib (first approved), dasatinib, and nilotinib.
The choice among these agents depends on several factors:
- Prior treatment history and prior TKI exposure
- Resistance mutation profile (particularly BCR-ABL1 kinase domain mutations)
- Individual patient tolerability and comorbidities
- Drug-drug interaction potential
- Patient and family preference regarding administration requirements
Bosutinib's dual Src/Abl inhibition mechanism provides a distinct profile that may benefit patients with specific resistance patterns. Src kinase inhibition may contribute to activity against certain BCR-ABL1 mutations that confer resistance to other TKIs.
What Is the Regulatory Significance of This Approval?
The pediatric approval of bosutinib addresses an unmet need in a rare disease population. Pediatric CML represents a small fraction of total CML cases, historically limiting the development of pediatric-specific evidence. Treatment decisions often relied on extrapolation of adult clinical data.
The FDA approval based on dedicated pediatric trial data from the BCHILD study provides clinicians with evidence-based dosing and safety information specific to children. This represents the standard regulatory pathway for pediatric oncology indications: initial adult approval, development of a pediatric study plan, and submission of a supplemental new drug application supported by pediatric clinical trial data.
The approval was processed under standard review timelines, reflecting the availability of existing treatment options for this patient population. No priority review or accelerated approval pathway was utilized.
Unmet Medical Need in Pediatric CML
Pediatric CML is a rare malignancy that accounts for approximately 2-3% of all childhood leukemias. The small patient population historically limited the development of pediatric-specific therapies and dosing guidelines.
TKI therapy has transformed CML from a fatal disease to a manageable chronic condition for most patients. However, children face unique challenges including long-term toxicity concerns affecting growth, development, and organ function over decades of treatment.
The approval of bosutinib for pediatric CML expands therapeutic options, enabling clinicians to tailor treatment based on individual patient factors including prior therapy response, tolerability, and resistance mutation status.
Future Outlook
The pediatric approval establishes a foundation for long-term follow-up studies characterizing the durability of response and late effects of bosutinib therapy in children. Ongoing post-marketing surveillance will continue to characterize the safety profile in pediatric patients.
Future investigations may explore bosutinib in combination with other agents, treatment-free remission protocols in pediatric patients achieving deep molecular responses, and the drug's activity against specific resistance mutations.
The availability of multiple approved TKIs for pediatric CML enables treatment sequencing strategies and may support future trials comparing frontline TKI options specifically in children.
Frequently Asked Questions
When did the FDA approve Bosulif for pediatric CML?
The FDA approved bosutinib (Bosulif) for pediatric CML on September 26, 2023, for patients aged 1 year and older with chronic phase Philadelphia chromosome-positive CML who are newly diagnosed or resistant/intolerant to prior therapy.
What were the efficacy results in the BCHILD trial?
In the BCHILD trial, newly diagnosed pediatric patients showed 76.2% major cytogenetic response, 71.4% complete cytogenetic response, and 28.6% major molecular response. For resistant/intolerant patients, major cytogenetic response was 82.1%.
What is the pediatric dosing for Bosulif?
For newly diagnosed CML, the recommended dose is 300 mg/m² orally once daily with food. For resistant/intolerant CML, the dose is 400 mg/m² orally once daily with food. Capsule contents can be mixed with applesauce or yogurt for patients unable to swallow capsules.
What adverse events are common with bosutinib in children?
Common adverse events in pediatric patients receiving bosutinib include diarrhea, abdominal pain, vomiting, nausea, rash, fatigue, hepatic dysfunction, headache, decreased appetite, and constipation.
How does bosutinib compare to other TKIs for pediatric CML?
Bosutinib joins imatinib, dasatinib, and nilotinib as FDA-approved TKIs for pediatric CML. The choice among agents depends on prior treatment history, resistance patterns, tolerability profiles, and clinical judgment. Bosutinib offers a dual Src/Abl inhibition mechanism.
Primary Sources
- FDA. Bosulif (bosutinib) Full Prescribing Information. September 2023. https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/203341s025lbl.pdf
- ClinicalTrials.gov. Study of Bosutinib in Pediatric Patients With Philadelphia Chromosome-positive (Ph+) CML (BCHILD). NCT04258943. https://clinicaltrials.gov/study/NCT04258943
- FDA. Drugs@FDA: Bosulif Approval History. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm
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