Vincristine Pharmacokinetics in Infants

PRIMARY OBJECTIVE:

I. To validate body surface area (BSA)-banded infant dosing tables by comparing vinCRIStine drug exposure, defined as the area under the concentration-time curve for the elimination phase (AUCelim), in infants and young children dosed according to the table to older children dosed according to BSA.

SECONDARY OBJECTIVE:

I. To estimate intra- and inter-age group variability (CV) using non-compartmental analysis (NCA) and population pharmacokinetic (PK) methods.

EXPLORATORY OBJECTIVES:

I. To correlate higher AUCelim with the presence of functionally impaired single nucleotide polymorphisms (SNP) of CYP3A4 and CYP3A5.

II. To assess vinCRIStine dose modifications in infants receiving weekly vinCRIStine dosed according to the BSA-banded infant dosing tables.

OUTLINE:

Patients receive vincristine intravenously (IV) per standard of care (SOC). Patients undergo collection of blood samples at baseline (before first vincristine dose), and 2, 6-8, and 18-24 hours after a dose of vincristine. Patients may also undergo collection of blood samples with a second SOC vincristine dose at the same time points.

Patients are followed for dose modifications for a period of 42 days (when receiving weekly dosing of vincristine).

Inclusion criteria

• Patients must be =< 12 years of age at the time of study enrollment. Patients will be stratified into 4 age groups:

• 0 to 6 months
• 6 months and 1 day to 12 months
• 12 months and 1 day to 36 months
• 36 months and 1 day to 12 years with a BSA ≥ 0.6 m^2
• Newly diagnosed and relapsed cancer diagnosis that is being treated with vinCRIStine at the 1.5 mg/m^2 dose level
• Any disease status
• Patients must have a Lansky performance status of 50 or higher
• Patients must be receiving a treatment regimen that includes 1.5 mg/m^2 vinCRIStine (maximum dose 2 mg)
• Patients with a BSA < 0.6 m^2 must be dosed according to the Children's Oncology Group (COG) BSA-banded infant dosing table for the 1.5mg/m2 dose level for vinCRIStine

• Note: Patients can be studied after any dose of vinCRIStine
• Patients who are NOT enrolled on a COG clinical trial and who have a BSA < 0.6 m^2 and who are being dosed according to another infant dosing method (e.g., the 30-Rule) can receive a dose of vinCRIStine from the infant dosing table for the pharmacokinetic study. These patients will NOT be part of the Dose Modification Assessment
• Patients with a seizure disorder may be enrolled if on allowable anticonvulsants and well controlled as evidenced by no increase in seizure frequency in the prior 7 days
• Nervous system toxicities (Common Terminology Criteria for Adverse Events [CTCAE]) version (v)5 resulting from prior therapy must be grade =< 2
• Central venous access device in place (e.g., percutaneous indwelling central catheter [PICC], port, Broviac) or scheduled to be placed prior to the dose of vinCRIStine and that can be used for pharmacokinetic (PK) sampling
• VinCRIStine may be given as an outpatient, as long as all sample time points can be collected, which will require return for hour 24 sampling

Exclusion criteria

• Azoles antifungals and macrolide antibiotics: Patients who are currently receiving an azole or macrolide (e.g., fluconazole, isavuconazole, itraconazole, posaconazole, voriconazole, ketoconazole, eryromycin, clarithromycin, azithromycin, roxithromycin, or telithromycin) are not eligible
• CYP3A4/5 inducers/inhibitors: Patients receiving any medications or substances that are considered moderate or strong inhibitors or inducers of CYP3A4/5 are not eligible. Moderate or strong inducers or inhibitors of CYP3A4/5 should be avoided from 14 days prior to enrollment to the end of the study.

• Note the following are allowed:

• Dexamethasone for CNS tumors or metastases, on a stable dose
• Aprepitant for management of nausea and vomiting
• Anticonvulsants: Patients receiving moderate or strong CYP3A4/5 enzyme inducing anticonvulsants are not eligible.
• Patients with Charcot-Marie-Tooth disease
• A baseline neurological disorder with manifestations that overlap with vinCRIStine-associated neurotoxicities
• Patients being treated on a Children Oncology Group (COG) clinical trial, that does not use the infant dosing tables for vinCRIStine are not eligible for this study.
• Patients receiving a modified dose (< 1.5 mg/m^2) of vinCRIStine due to prior toxicity
• Patients who in the opinion of the investigator may not be able to comply with the sampling requirements of the study