A Pilot Study on ALK Gene Mutations in Neuroblastoma

• purpose Despite the advance of modern multimodal therapy including surgery, chemotherapy, autologous stem cell transplantation, radiation therapy, and differentiation therapy, most children with NB are diagnosed with metastatic diseases and suffer from a dismal outcome. There is an unmet need for the development of novel target therapy in NB. Among all recently identified targets, ALK gene mutations have been found in approximately 10% of high-risk NB patients and are the treatment target of several promising agents that have already been tested in clinical trials, including crizotinib, which is to be available in Taiwan soon. This study aims to evaluate the prevalence of mutations and copy number aberrations of the ALK oncogene in prospective and previously treated NB patients' tumor sample (from surgical specimens) and germ-line (peripheral blood lymphocytes). The messenger ribonucleic acid(mRNA) and protein expression levels of ALK will also be analyzed. The results will be correlated with the clinical characteristics and pathological findings of this NB cohort.
• technique Prospective cases: Cryopreservation of tumor samples Retrospective cases: Archived tumor Sequencing: point mutation array-based comparative genomic hybridization(aCGH) & MLPA（multiplex ligation-dependent probe amplification）：analyze copy number alterations (CNAs) compare to clinical data
• expected results The results from this study may serve as the first report on ALK gene mutations of NB in Taiwan. We anticipate that 5-15% of NB tumors carry with common ALK mutations. Genome-wide CNAs profiling by aCGH can help us to categorize the genomic types of NB patients based on published guidelines, while the presence of ALK mutation or amplification may or may not be associated with subtypes with worse outcome. Some patients may have high ALK expression level without bearing common mutations on ALK gene locus, and we may identify novel mutation points in this patient cohort. Finally, we will probably find significant prognostic value of ALK gene mutation, which may be independent from other known risk factors, such as age, stage, MYCN amplification, and genomic pattern.

Based on these results, we are able to develop standardized protocol for diagnosing ALK mutations for Taiwanese NB patients. With the development of ALK genetic testing, a phase II clinical trial of an ALK inhibitor in high-risk NB patients with relapsed or refractory disease may subsequently be conducted and may improve the treatment outcome of the patients.