Efficacy and Safety Study of Fosaprepitant (MK-0517) Plus Ondandsetron Versus Ondansetron Alone for the Prevention of Chemotherapy-Induced Nausea and Vomiting in Pediatric Participants (MK-0517-044)

In Cycle 1, participants will receive double-blind study drug (fosaprepitant plus
ondansetron with or without dexamethasone OR ondansetron with or without dexamethasone).
Upon completion of Cycle 1, participants may have the option to continue for up to 5
additional open-label cycles, receiving fosaprepitant plus ondansetron with or without
dexamethasone.

Inclusion Criteria:

- Be 0 (at least 37 weeks gestation) to 17 years of age at time of randomization

- Have a Lansky Play Performance score ≥60 (participants ≤16 years of age) or a
Karnofsky score ≥60 (participants >16 years of age)

- Have a predicted life expectancy ≥3 months

- Be receiving chemotherapeutic agent(s) associated with moderate or high risk of
emetogenicity, or a chemotherapy regimen not previously tolerated due to vomiting

- Have a preexisting functional central venous catheter available for study drug
administration

- Is male OR is female who is not of reproductive potential OR is female who is of
reproductive potential and agrees to avoid becoming pregnant in the 28 days prior to
receiving study drug, while receiving study drug and for at least 30 days after last
dose of study drug.

Exclusion Criteria:

- Has vomited in the 24 hours prior to chemotherapy initiation on Treatment Day 1

- Has a symptomatic primary or metastatic central nervous system (CNS) malignancy with
nausea and/or vomiting (asymptomatic participants may participate in study)

- Will be receiving stem cell rescue therapy in conjunction with study-related course
of emetogenic chemotherapy or during the 14 days following administration of
fosaprepitant/placebo for fosaprepitant

- Has received or will receive total body irradiation of radiation therapy to the
abdomen or pelvis in the week prior to Treatment Day 1 and/or during the diary
reporting period (120 hours following initiation of chemotherapy)

- Has had benzodiazepine, opioid or opioid like therapy initiated within 48 hours prior
to study drug administration, or is expected to receive within 120 hours following
initiation of chemotherapy except for single doses of midazolam, temazepam or
triazolam

- Has started on systemic corticosteroid therapy within 72 hours prior to study drug
administration or is expected to receive a corticosteroid as part of the chemotherapy
regimen

- Is currently taking, or has taken within 48 hours of Treatment Day 1 the following
drugs with antiemetic properties: 5-HT3 antagonists (e.g., ondansetron), benzamides
(e.g., haloperidol), cyclizine, domperidone, herbal therapies with potential
antiemetic properties, olanzapine, phenothiazines (e.g., prochlorpenzine),
scopolamine (this is not an exhaustive list)

- Is or has an immediate family member who is investigational site or sponsor staff
directly involved with this study

- Is currently a user of any recreational or illicit drugs (including marijuana) or has
current evidence of drug or alcohol abuse or dependence

- Is mentally incapacitated or has a significant emotional or psychiatric disorder

- Is pregnant or breast feeding

- Is allergic to fosaprepitant, aprepitant (MK-0869), ondansetron, or any other 5-HT3
antagonist

- Has a known history of QT prolongation or is taking any mediation that is known to
lead to QT prolongation

- Has an active infection (e.g., pneumonia), congestive heart failure, bradyarrythmia,
any uncontrolled disease (e.g., diabetic ketoacidosis, gastrointestinal obstruction)
except for malignancy

- Has ever participated in a previous study of aprepitant or fosaprepitant or has taken
an investigational drug with the last 4 weeks.