Molecular Characterization of Oligo – Metastatic Gastrointestinal Tumors

Poly- and oligo-metastatic tumors (from the Greek oligos: little) have a different clinical and biological behavior (1). The definition of “true oligo-metastatic disease” (with “good prognosis”) is retrospective, as many patients, initially considered oligo-metastatic, develop poly-metastatic disease within 1 year. Oligometastases are initially identified as a tumor involving no more than three lesions per organ, with a maximum tumor size of less than 7 cm or a primary tumor (active or resected) with metastatic masses ≤5 easily resectable or controllable with approaches local. In recent years, our group has been involved in the study of oligo-metastatic disease in colorectal cancers, demonstrating that it has different genetic characteristics compared to the poly-metastatic one. In particular in 9 out of 11 patients. with oligometastatic disease and Kras mutated on the primary tumor, the absence of KRAS mutations on the progressing tumor was highlighted. This situation was found only in 1 patient out of 52 of those with progressive poly-metastatic disease, while in most cases there was a gain of KRAS mutations (8). Therefore, oligo-metastatic disease represents an entity with specific molecular characteristics and not simply a transitory evolutionary moment towards a more aggressive clinical behavior. The aim of the project will be to evaluate the genetic profile of oligo-metastatic tumors of gatro-enteric neoplasms by means of multigenic sequencing techniques, both at diagnosis and development of metastases (dynamic evaluation). The primary objective is to predict the true oligo-metastatic status (indolent disease with "good prognosis") among patients who begin with an oligo-metastatic disease. Using latest generation “parallel” multigenic sequencing technologies (Next Generation Sequencing, NGS), we will evaluate the “molecular landscape” of a large number of neoplasms in a short time and with very high reliability. 1) Selection and sample collection phase (months 0-18 °). Patients will be recruited at the National Cancer Institute of Naples, IRCCS "G. Pascale ”, SSD Innovative Therapies Abdominal Metastases and followed by oncologists specialized in the treatment of gastro-enteric neoplasms. Clinical and pathological data will be collected in compliance with all applicable regulations including privacy, informed consent and, where required, obtaining the approval of the ethics committee; tissue biological samples of gastro-enteric neoplasms (colon, stomach, biliary tract, exocrine glands of the digestive tract), both paraffin-embedded tissue (neoplastic and non-neoplastic components, as control) and liquid biopsies (where no tissue is available). 2) Molecular analysis phase (months 18th - 24th). Selected samples will be molecularly characterized using the TruSight ™ Oncology 500 (TSO500) assay. This test is designed to detect multiple classes of mutations including single nucleotide variants, small insertions / deletions, microsatellite instability (MSI) and mutational load (TMB). Finally, the libraries will be sequenced on Illumina NovaSeq6000 machines. 3) Phase of biostatistic analysis (months 24th - 34th). Genetic data will be subjected to biostatistical evaluation to obtain significance data, select the molecular alterations with the most probable biological significance and to cross-reference molecular and clinical data. 4) Phase of data interpretation, bibliographic research, formulation of hypotheses, writing of scientific articles (months 34th - 36th). The data obtained by biostatistic analysis will be interpreted taking into consideration the molecular pathways involved in the specific neoplasms and the currently available therapies. EXPECTED RESULTS AND POSSIBLE RISK STRATEGIES Identify new molecular markers specific to oligo-metastatic gastro-intestinal tumors. This may have diagnostic, prognostic and predictive repercussions. Furthermore, the data obtained could be the starting point for further research aimed at the proteomic and epigenetic validation of what has been observed and at the development of new molecular target therapies.