Sequential Analysis Of RTK And Downstream Signaling Pathways During Individualized Personal Therapy Of Alveolar Rhabdomyosarcoma: A Case Report

New therapies are needed primarily for children with advanced solid tumors who fail standard chemotherapy regimens. One of the very promising strategies in cancer treatment is based on the interference with or blocking of signaling pathways in the tumor cells. Very important group of these signal transducers is a family of receptor tyrosine kinases (RTKs) with downstream signalling pathways PI3K/AKT and RAS/RAF/MAPK. This study was aimed as a detailed analysis of activated signaling pathways in tumor tissue samples taken from the patient suffering with alveolar rhabdomyosarcoma of the ala of nose.

Four samples of tumor tissue subsequently obtained from the patient were analyzed for activity of cell signaling pathways. Human Phospho-RTK Array Kit (R&D Systems) was used to determine the relative levels of tyrosine phosphorylation of 49 different RTKs. Human Phospho-MAPK Array Kit (R&D Systems) was employed for the detection of phosphorylation status of 26 MAPKs, serine/threonine kinases and other signalling proteins.

We analyzed the primary tumor, relapsed primary tumor as well as two metastatic lymph nodes at different steps during the course of the disease. In the biopsy sample of the primary tumor we observed very high phosphorylation of EGFR and mediate phosphorylation of PDGRβ. First complete remission was achieved after 3 cycles of chemotherapy and adjuvant radiotherapy; however, tumor relapsed (EFS 16 months). Analysis the relapsed tumor from primary localisation showed decrease of phosphorylated EGFR and InsR. Second complete remission was achieved after 6 cycles of chemotherapy. The patient was treated with individualized metronomic chemotherapy together with pazopanib and sirolimus, but the metastatic relapse was diagnosed 6 months later. Progression of the disease affected locoregional lymph node in which was observed increase of phosphorylated IGF-I and HGF receptors as well as CREB and ERK2. Subsequently, paclitaxel, erlotinib, and sunitinib were added to the treatment scheme. Last sample (metastatic lymph node) was analysed 3 months later and the phosphorylation of most of all RTKs was abolished. Despite the intensive individualized therapy, the patient died in 3 months.

Based on the obtained data, specific small-molecule inhibitors were incorporated into the treatment protocol. Although any encouraging effects of this therapy were not observed at clinical levels - probably because of the advanced stage of metastatic disease - changes in phosphorylation of relevant signalling proteins were detected.

Grant support: AZV MZCR 16-34083A and LQ1605.