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Targeted Therapies for the Treatment of Brain Metastases in Solid Tumors
Jan-Paul Bohn1, Georg Pall2, Guenther Stockhammer3
1Department of Internal Medicine V, Medical University of Innsbruck, Anichstrasse 35, A-6020, Innsbruck, Austria. Jan-Paul.Bohn@i-med.ac.at.
Abstract:
Brain metastases are a major cause of morbidity and mortality in cancer patients. While the mainstay treatment comprises surgery and radiation therapy, the role of systemic agents remains controversial. In general, it has been presumed that poor blood-brain barrier (BBB) penetration and inherently more resistant metastatic brain disease preclude a favorable systemic treatment approach. However, a better understanding of tumor biology and the subsequent development of targeted drugs have reawakened interest in systemic therapy. Despite still limited brain distribution, a variety of targeted drugs have demonstrated activity in brain metastases in early clinical trials. Nevertheless, disease progression commonly occurs, and it remains to be elucidated whether limited CNS drug distribution or the acquisition of resistant metastatic clones must be held responsible for this prognosis. Moreover, micrometastatic brain disease beyond an intact BBB-and ultimately prevention of brain metastasis formation-may generally remain inaccessible for first-generation targeted agents with poor CNS penetration. To overcome limited brain distribution and possibly emerging acquired resistance, highly potent next-generation targeted drugs with enhanced CNS distribution have been developed. In view of this emerging but yet undefined role of targeted therapies in the treatment of brain metastases from solid tumors, this review aims to summarize the current knowledge from clinical trials and discusses clinically relevant obstacles to overcome.
Insights
Systemic targeted drugs show promise for brain metastases, but limited brain penetration and resistance are challenges. Next-generation agents with improved CNS distribution are being developed to overcome these obstacles.
Area of Science:
- Neuro-oncology
- Translational medicine
- Clinical pharmacology
Background:
- Brain metastases significantly increase cancer patient morbidity and mortality.
- Traditional treatments like surgery and radiation have limitations.
- Systemic therapy for brain metastases is historically controversial due to poor blood-brain barrier (BBB) penetration and tumor resistance.
Purpose of the Study:
- To review the current clinical evidence for targeted therapies in brain metastases.
- To discuss the challenges and opportunities in developing effective systemic treatments for brain metastases.
- To explore the role of next-generation targeted drugs with enhanced central nervous system (CNS) distribution.
Main Methods:
- Review of clinical trials investigating targeted agents in brain metastases.
- Analysis of factors influencing drug distribution across the BBB.
- Discussion of mechanisms of resistance in metastatic brain disease.
Main Results:
- Early clinical trials show some activity of targeted drugs in brain metastases, despite limited CNS penetration.
- Disease progression remains common, with limited CNS drug distribution and acquired resistance as potential causes.
- Next-generation targeted drugs with enhanced CNS penetration are emerging to address these limitations.
Conclusions:
- Targeted therapies are increasingly relevant for brain metastases, but overcoming CNS drug delivery and resistance is crucial.
- Enhanced CNS distribution of next-generation agents offers potential for improved outcomes.
- Further research is needed to define the optimal role of systemic targeted therapies in managing brain metastases.
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