Biological Treatments of Neurofibromatosis Type 2 and Other Skull Base Disorders

Latest Developments in Targeted Biological Therapies in the Management of Chordoma and Chondrosarcoma

STUDY DESIGN

Systematic review.

OBJECTIVES

The objective of this review paper was to summarize targeted molecular therapy options for spinal chordoma and chondrosarcoma, and to provide an update on the relevant clinical trials open for recruitment.

METHODS

A systematic review of the current literature was performed, according to PRISMA guidelines, to summarize the latest developments in non-surgical molecular treatment options for low grade malignant primary spinal tumours. We also summarize those actively recruiting clinical trials based on clinicaltrials.gov.

RESULTS

A total of 73 studies and completed clinical trials were reviewed. Twenty actively recruiting clinical trials (eight for chordoma and twelve for chondrosarcoma) were identified.

CONCLUSIONS

There is a strong need to find new therapeutic options to complement surgical resection and radiation therapy, which remain the cornerstone of management. Targeted therapies against molecular pathways show promise as compared to conventional chemotherapy.

Determinants of quality of life following resection of skull base tumors: a systematic review

Background

Skull base tumors represent a small subset of intracranial neoplasm. Due to their proximity to critical neurovascular structures, their resection often leads to morbidity. As a result, surgical interventions can exacerbate symptoms or cause new deficits, thereby impacting the patients' perceived quality of life (QoL). The factors influencing QoL in patients with skull base tumors remain underexplored. This systematic review aims to synthesize current research on QoL outcomes and identify potential factors influencing QoL in these patients.

Methods

A systematic literature review was conducted in PubMed using the keywords "Skull Base" AND "Quality of Life." A total of 815 studies published up to January 31, 2024, were screened. After abstract review, 656 studies were excluded, and 159 studies underwent full-text review. The wide variability in study methodologies and utilized QoL instruments made only a descriptive comparison possible.

Results

In total, 113 studies were systematically reviewed. Publications focusing on the same tumor type or localization were compared. The majority of studies addressed tumors of the anterior skull base, with pituitary adenomas, meningiomas and vestibular schwannomas being the most commonly represented. The impact of surgery on QoL is often underestimated by caregivers and has a more profound effect on patients than expected by surgeons. A transient decline in QoL after surgery was observed across almost all studies regardless of localization and entity. Factors influencing QoL included age, gender, tumor localization, surgical approach, tumor type, extent of resection, preoperative clinical status and neurological deficits. Radiotherapy and recurrent surgeries were predictors of poorer QoL. Early psychological intervention in complex tumors appears to enhance QoL. Some successful sealing techniques, such as nasoseptal flaps and lumbar drains, affected QoL. However, variability in study methodologies reduced the validity of the findings.

Conclusion

This review highlights the significant impact of skull base tumor surgery on patients' QoL. Given the major oncological and surgical challenges presented by skull base tumors, their treatment significantly affects QoL, and gross total resection (GTR) should not always be the primary goal. Additionally, recognizing and addressing the modifiable and non-modifiable factors influencing QoL is crucial for improving patient outcomes and providing personalized care.

Culture of attenuated Salmonella Typhimurium VNP20009 in animal-product-free media does not alter schwannoma growth control

Schwannomas are slow-growing benign peripheral nerve sheath tumors derived from Schwann-lineage cells that develop in association with NF2-related schwannomatosis (NF2) and schwannomatosis (NF3), as well as spontaneously. Individuals affected with NF2 and NF3 have multiple schwannomas with tumors arising throughout life. Surgical resection, the standard management, is limited in scope and efficacy and is itself associated with significant morbidity. We have previously shown that direct intratumoral injection of attenuated Salmonella Typhimurium (S. Typhimurium), strain VNP20009, showed a potent anti-tumor effect in preclinical NF-2 schwannoma models. The United States Federal Drug Administration (FDA) requires that bacterial products utilized in clinical trials be produced without exposure to animal-derived-products. In this context, we developed, characterized, and tested the antitumor efficacy of an attenuated S. Typhimurium serially passaged in animal-product-free media, naming it VNP20009-AF for "VNP20009-animal-product-free." Our in vitro data did not indicate any significant changes in the viability, motility, or morphology of VNP20009-AF, compared to its parental strain. In vivo efficacy data demonstrated that VNP20009-AF and VNP20009 controlled tumor growth to the same degree in both human NF2-schwannoma xenograft and murine-NF2 schwannoma allograft models. Together, these data support the use of VNP20009-AF for the translation of bacterial schwannoma therapy into clinical trials.

Schwannoma Gene Therapy via Adeno-Associated Viral Vector Delivery of Apoptosis-Associated Speck-like Protein Containing CARD (ASC): Preclinical Efficacy and Safety

Schwannomas are tumors derived from Schwann-lineage cells, cells that protect and support myelinated nerves in the peripheral nervous system. They are typically slow-growing, encapsulated and benign. These tumors develop along peripheral, spinal and cranial nerves causing pain, sensory-motor dysfunction and death. Primary treatment for schwannoma is operative resection which can be associated with significant morbidity. Pharmacotherapy is largely restricted to bevacizumab, which has minimal or no efficacy for many patients and can be associated with treatment-limiting adverse effects. Given the suffering and morbidity associated with schwannoma and the paucity of therapeutic options, there is an urgent need for safe and effective therapies for schwannomas. We previously demonstrated that adeno-associated virus serotype 1 (AAV1) vector mediated delivery of the inflammasome adaptor protein, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) under the control of the P0 promoter, produced a prolonged reduction in tumor volume and tumor-associated pain in human xenograft and mouse syngeneic schwannoma models. Here, we present data essential for the translation of our AAV1-P0-ASC schwannoma gene therapy to clinical trials. We determine the minimum effective dose of AAV1-P0-hASC required to induce an anti-tumor effect in the xenograft human-schwannoma model. We also show that the presence of preexisting AAV1 immunity does not alter the antitumor efficacy of AAV-P0-mASC in a syngeneic mouse schwannoma model. Furthermore, the maximum deliverable intratumoral dose of AAV1-P0-ASC was not associated with neuronal toxicity in immunocompetent mice. Taken together, these safety and efficacy data support the translation of the AAV1-P0-ASC schwannoma gene therapy strategy to clinical trials.