see also Intracranial metastases.
Despite the frequency of brain metastases, prospective trials in this patient population are limited, and the criteria used to assess response and progression in the CNS are heterogeneous 1).
This heterogeneity largely stems from the recognition that existing criteria sets, such as RECIST 2) 3).
Whether brain metastases harbor distinct genetic alterations beyond those observed in primary tumors is unknown.
Brastianos et al. detected alterations associated with sensitivity to PI3K/AKT/mTOR, CDK, and HER2/EGFR inhibitors in the brain metastases. Genomic analysis of brain metastases provides an opportunity to identify potentially clinically informative alterations not detected in clinically sampled primary tumors, regional lymph nodes, or extracranial metastases 4).
CDH2, KIFC1, and FALZ3
Randomized controlled trials
There is a lack of prospective randomized studies. Based on retrospective case series, international guidelines recommend the harvesting (if required, stereotactically guided) of tissue for histological and molecular diagnosis in cases of unknown or possibly competing for underlying systemic malignant diseases, in cases of suspected tumor recurrence, and with regard to the evaluation of targeted therapies taking into account molecular heterogeneity of primary and secondary tumors. Surgical resection is particularly valuable for the treatment of up to three space-occupying cerebral metastases, especially to achieve clinical stabilization to allow further non-surgical treatment For cystic metastasis, a combination of stereotactic puncture and radiotherapy may be useful. Meningeal carcinomatosis can be treated with intrathecal medication via an intraventricular catheter system. Ventriculoperitoneal shunts represent an effective treatment option for patients with tumor-associated hydrocephalus.
Neurosurgical procedures are of central importance in the multimodal treatment of cerebral metastases. The indications for neurosurgical interventions will be refined in the light of more effective radiation techniques and systemic treatments with new targeted therapeutic approaches and immunotherapies on the horizon 5).
Zhu et al. reported a medium-throughput drug screening platform (METPlatform) based on organotypic cultures that allow evaluating inhibitors against metastases growing in situ. By applying this approach to the unmet clinical need of brain metastases, they identified several vulnerabilities. Among them, a blood-brain barrier permeable HSP90 inhibitor showed high potency against mouse and human brain metastases at clinically relevant stages of the disease, including a novel model of local relapse after neurosurgery. Furthermore, in situ proteomic analysis applied to metastases treated with the chaperone inhibitor uncovered a novel molecular program in brain metastases, which includes biomarkers of poor prognosis and actionable mechanisms of resistance. The work validates METPlatform as a potent resource for metastases research integrating drug screening and unbiased omics approaches that are compatible with human samples. Thus, this clinically relevant strategy is aimed to personalize the management of metastatic disease in the brain and elsewhere 6).