BIOM-103. A SUCCESSFUL CASE REPORT: RESPONSE TO ALECTINIB AND LOCAL RADIOTHERAPY IN AN ALK REARRANGED NON-SMALL CELL LUNG CANCER PATIENT HARBORING MULTIPLE BRAIN METASTASES

Abstract BACKGROUND Non-small cell lung cancer (NSCLC) accounts for 80% of lung cancer cases, with Anaplastic Lymphoma Kinase (ALK) gene rearrangements present in 7% of patients. Central nervous system (CNS) metastases occur in 30–50% of ALK+ cases and are associated with poor prognosis (<12 months). NSCLC brain metastases are often treated with stereotactic radiosurgery or whole-brain radiotherapy. Due to the gene fusion-driven nature of ALK+ tumors, the tyrosine kinase inhibitor Alectinib have emerged as promising treatment option. While Alectinib is the standard of care for NSCLC peripheral lesions, its high CNS penetration supports its use in brain metastases. This report describes a Brazilian patient with ALK+ lung adenocarcinoma and CNS metastases who achieved complete response to targeted therapy. METHODS Clinical data, NMR images, histopathological and immunohistochemistry analyses, neurosurgery information and treatment protocol were obtained from retrospective electronic local medical records from the Sírio-Libanês Hospital, Brazil. RESULTS A 51-year-old woman presented memory loss and disorientation. NMR showed several nodular brain lesions in both hemispheres and cerebellum, with the largest (63×42mm) causing mass effect and ventricle compression. Several markers associated with brain metastases of lung cancer (TTF1|NapsinA|CK7) and colorectal cancer (SATB2|CDX2|SMAD4|CK20) were analyzed for differential diagnosis. PET/CT revealed bilateral lung nodules and paratracheal adenopathy. Molecular analysis (qPCR) of a cervical lymph-node biopsy was made to alterations in BRAF|EGRF|KRAS|NTRK1/2/3|MET|RET|ROS1|ALK genes. ALK-fusion-positive indicating lung adenocarcinoma was observed. Alectinib 600mg twice daily was prescribed. Five months later, radiotherapy for mediastinal disease and radiosurgery for surgical cavities and remaining brain lesions was performed. Six-month follow-up PET/CT showed a complete peripheral response, with sustained CNS control on Alectinib maintenance. CONCLUSIONS This case highlights the potential of combining targeted therapies, neurosurgery, and localized radiotherapy to achieve complete CNS responses in ALK+ NSCLC brain metastases, reinforcing the value of personalized, multimodal treatment strategies in oligometastatic ALK+ NSCLC.