What is the role of repurposed medications, such as bevacizumab (anti-VEGF antibody), in the treatment of choroid plexus tumors?

Repurposed Medications for Choroid Plexus Tumors

There is currently no established role for bevacizumab or other repurposed medications in the treatment of choroid plexus tumors, as no guideline-level evidence or high-quality trials support their use in this specific tumor type.

Current Evidence Landscape

Absence of Guideline Support

The available neurosurgical and neuro-oncology guidelines do not address choroid plexus tumors specifically when discussing emerging or repurposed therapies 1. The Congress of Neurological Surgeons guidelines on emerging therapies focus exclusively on metastatic brain tumors and gliomas, not primary choroid plexus neoplasms 1.

Bevacizumab Context in Brain Tumors

While bevacizumab has been studied extensively in other brain tumor contexts, its role remains limited:

• For recurrent glioblastoma: Bevacizumab received FDA accelerated approval but showed only progression-free survival benefit without overall survival improvement 1
• For brain metastases: The 2025 CNS guidelines suggest bevacizumab may improve CNS control, PFS, and OS when added to treatment regimens for metastatic brain tumors, but this applies only to metastases from systemic cancers, not primary brain tumors like choroid plexus carcinomas 1
• Mechanism limitations: Bevacizumab's anti-VEGF activity addresses vascular permeability and angiogenesis, which are not established primary drivers of choroid plexus tumor biology 1

Established Treatment Approach for Choroid Plexus Tumors

Primary Treatment Strategy

Maximal safe surgical resection remains the cornerstone of treatment for both choroid plexus papillomas (CPP) and choroid plexus carcinomas (CPC) 2.

Histology-Based Management

For Choroid Plexus Papilloma (CPP):

• Complete surgical resection followed by observation ("wait and see" approach) 2
• 10-year survival rates of 77% with appropriate surgical management 2

For Choroid Plexus Carcinoma (CPC):

• Radical surgical resection followed by adjuvant therapy 2
• Radiotherapy significantly improves survival in CPC patients 2
• 10-year survival rates of only 35%, indicating need for multimodal therapy 2

Chemotherapy for Recurrent or Residual Disease

Evidence-based chemotherapy agents for CPC include:

• Etoposide: Highest response rate (17/36 patients) and statistically significant survival benefit in meta-analysis 3
• Cyclophosphamide, carboplatin: Demonstrated survival benefit in comparative analyses 3
• Combination regimens: Cisplatin/bleomycin/vinblastine showed response in recurrent CPP 4; high-dose ifosfamide/carboplatin/etoposide achieved temporary remission in adult CPC 5

Novel combinations under investigation:

• Melphalan combined with elimusertib (ATR inhibitor) showed significant survival improvement in preclinical CPC models with intra-arterial delivery 6
• Topotecan/elimusertib combination demonstrated synergistic activity in patient-derived CPC cell lines 6

Why Bevacizumab Is Not Recommended

Lack of Disease-Specific Evidence

• No published trials, case series, or case reports document bevacizumab use specifically for choroid plexus tumors 4, 2, 5, 3, 6
• The comprehensive meta-analysis of 906 choroid plexus tumor patients (through 2007) and subsequent literature do not mention anti-VEGF therapy 2, 3

Biological Rationale Concerns

• Choroid plexus tumors are epithelial neoplasms arising from choroid plexus epithelium, not primarily vascular tumors 2
• The pathophysiology differs fundamentally from conditions where bevacizumab shows benefit (glioblastoma, metastatic disease with significant vasogenic edema) 1

Risk-Benefit Considerations

• Bevacizumab carries significant risks including hypertension, impaired wound healing, colonic perforation, and thromboembolism 1
• Without evidence of efficacy in choroid plexus tumors, these risks cannot be justified 1

Clinical Algorithm for Treatment Selection

At diagnosis:

1. Pursue maximal safe surgical resection as primary intervention 2
2. Obtain definitive histopathology (CPP vs CPC) 2

For CPP with complete resection:

• Observation with serial imaging 2

For CPC or incompletely resected CPP:

• Adjuvant radiotherapy for CPC 2
• Consider etoposide-based chemotherapy for residual/recurrent disease 3
• Enrollment in clinical trials investigating novel combinations (e.g., DNA-damaging agents with ATR inhibitors) 6

For recurrent disease after standard therapy:

• Re-resection if feasible 2
• Salvage chemotherapy with etoposide-containing regimens 3
• Consider enrollment in trials of novel targeted combinations rather than empiric bevacizumab 6

Critical Pitfalls to Avoid

• Do not extrapolate bevacizumab data from glioblastoma or brain metastases to choroid plexus tumors, as these are distinct pathological entities with different biology 1, 2
• Do not delay definitive surgical intervention in favor of medical therapy, as surgery provides both diagnostic and therapeutic benefit 2
• Do not omit adjuvant radiotherapy in CPC, as it significantly improves survival 2
• Do not overlook etoposide when selecting chemotherapy regimens, as it has the strongest evidence base for CPC 3