International multicenter observational study to determine the diagnostic sensitivity of plasma metanephrines and urinary catecholamines and metabolites compared to standard evaluation procedures in children with high risk neuroblastoma

Neuroblastoma is the third most frequent tumor in children after leukemia and
brain tumors and is the most common cancer in infants.
Various tools are used to diagnose neuroblastoma and monitor its response to
treatment, including the assessment of urinary excretion of catecholamines and
its metabolites. The currently used biochemical diagnostic criteria were
established on the basis of an international consensus: the urinary dosage of
dopamine and its metabolites VMA (vanillin-mandelic acid) and HVA
(homo-vanillic acid) is considered the gold standard for diagnosis and
biochemical monitoring of the disease. However, catecholamines and the HVA/VMA
metabolites remain insufficient indicators for the diagnosis and therapeutic
follow-up of neuroblastomas. Data from Strenger et al. confirmed a sensitivity
of 80.7% for the measurement of dopamine alone and 91.2% for the combination of
dopamine, VMA and HVA. Recently Verly et al performed a retrospective urine
analysis in 301 neuroblastoma patients at diagnosis, measuring a total of 8
metabolites for diagnostic accuracy (VMA, HVA, 3-methoxytyramine [3MT],
dopamine, epinephrine [E], metanephrine [MN], norepinephrine [NE] and
normetanephrine [NMN]), and obtained an overall 89% sensitivity for NMN as
single diagnostic metabolite, and a 95% sensitivity when combining all 8
metabolites.
Moreover, studies on pheochromyocytoma, another tumor originating from the
neural crest and producing large amounts of metanephrines, showed that the
measurement of plasma metanephrines and in particular free metanephrines are
currently considered as the gold standard diagnosis tool for pheochromocytoma.
In patients with neuroblastoma, Peitzsch and al. showed that the diagnostic
sensitivity of 97.9% of 3MT or NE in plasma, in 94 patients, was significantly
higher than the diagnostic sensitivity of HVA and VMA in urine. A specific
feature for neuroblastoma is that these tumors secrete dopamine and its
methoxylated metabolite methoxytyramine. We postulate that plasma
methoxytyramine is a more sensitive biomarker than plasma dopamine because it
is produced directly by the tumor, is not reuptaken by receptors and exhibits a
longer half-life than dopamine. In addition, another advantage would be the
replacement of the urinary spot or inaccurate 24-hour urine collection in young
children by a blood sample taken during routine blood analysis.
In order to evaluate diagnostic significance of plasma metanephrines in
patients with neuroblastoma, we first established in a prospective study in a
cohort of 191 healthy children, boys and girls, aged 0-18 years, nonexistent
reference range curves for full baseline values for free and total plasma
metanephrines. In addition, we examined plasma metanephrines in 10 patients who
were routinely diagnosed with neuroblastoma. Total and free NMN and 3-MT showed
to be the best parameters with a 100% sensitivity at diagnosis
In conclusion, a prospective study is needed to confirm and establish the role
of new urinary and plasma biomarkers at diagnosis, follow-up and detection of
residual disease/relapse, applying a well-established, harmonized and approved
method of measurement to reduce variability between laboratories and to pick
out the most significant marker/s for future clinical use.

Primary objectives:
To demonstrate that diagnostic sensitivity of plasma metanephrines (free and
total) is superior to standard evaluation procedures (urinary Dopamine, HVA and
VMA) at diagnosis and end-of-induction assessment.

Secondary objectives:
• To evaluate whether diagnostic sensitivity of plasma metanephrines (free and
total) is equal/superior/inferior to urinary catecholamines and metabolites at
diagnosis and end-of-induction assessment.
• Correlate plasma metanephrines (free and total) and urinary catecholamines
and metabolites to outcome (end-of-induction remission) and compare to other
gold standard diagnostic and monitoring tools.
• Correlate plasma metanephrines (free and total) and urinary catecholamines
and metabolites to different disease subgroups, such as age at diagnosis,
disease stage, histology and molecular characteristics.

International multicenter prospective study
Duration: 2 years

This study enters the *A*very low risk category as it entails no more than
minimal risks and burdens for the participant. Indeed, the study procedure
(blood drawn for plasmatic dosage of metanephrines) will be performed during a
routine blood collection and will not require any additional venipuncture.
Specific analyses in urine will be performed on samples taken from routine
assessments.