Animal models have been commonly used in immunotherapy research to study the cell response to external agents and to assess the effectiveness and safety of new therapies. Over the past few decades, immunocompromised (also called immunodeficient) mice allowed researchers to grow human tumor cells without the impact of the host’s immune system. However, while this model is very valuable to understand the tumor biology and to understand the underlying mechanism of immunotherapy, the results may not always directly translate to humans. The tumor microenvironment has significant implications for tumor engraftment, growth, invasion, etc., and the immune system plays a critical role in shaping the tumor microenvironment. Human immunocompetent mice, also named humanized mice, are engineered mice that possess functional human immune cells. This in vivo model can be used to effectively study the effect of the human immune system to a human implanted tumor. Moreover, this can effectively mimic the response to treatment. This section is an overview of the current understanding of the different humanized mice that could be utilized to mimic the tumor microenvironment in chordoma.

For many spine surgeons, patients with metastatic cancer are often present in an emergent situation with rapidly progressive neurological dysfunction. Since the Patchell trial, scoring systems such as NOMS and SINS have emerged to guide the extent of surgical excision and fusion in the context of chemotherapy and radiation therapy. Yet, while multidisciplinary decision-making is the gold standard of cancer care, in the middle of the night, when a patient needs spinal surgery, the wealth of chemotherapy data, clinical trials, and other medical advances can feel overwhelming. The goal of this review is to provide an overview of the relevant molecular biomarkers and therapies driving patient survival in lung, breast, prostate, and renal cell cancer. We highlight the molecular differences between primary tumors (i.e., the patient’s original lung cancer) and the subsequent spinal metastasis. This distinction is crucial, as there are limited data investigating how metastases respond to their primary tumor’s targeted molecular therapies. Integrating information from primary and metastatic markers allows for a more comprehensive and personalized approach to cancer treatment.

Chordomas are rare, highly morbid tumors arising from notochordal progenitor cells along the spinal axis, associated with severe neurological complications and high recurrence rates. Their resistance to conventional therapies and limited options beyond surgical resection and high-dose radiation underscore the urgent need for novel therapeutic targets. Publicly available preliminary RNA sequencing data from the Chordoma Foundation identified chitinase-3-like 1 (CHI3L1), a secreted glycoprotein implicated in immune checkpoint regulation and epithelial–mesenchymal transition (EMT), as a promising candidate for chordoma immunotherapy. Yet, the comprehensive function of CHI3L1 in chordoma immune response remains unclear. To evaluate its presence in chordoma, we employed RNA-based analyses alongside enzyme-linked immunosorbent assays (ELISA) on commercially available chordoma cell lines (JHC7, U-CH12, U-CH1, U-CH1-N) and human chordoma tumor specimens. Our results demonstrate elevated CHI3L1 expression in chordoma cells relative to notochordal precursors, with comparative analyses revealing higher CHI3L1 expression in the primary tumor relative to recurrent samples. These findings suggest the potential role of CHI3L1 in chordoma tumorigenesis, emphasizing its relevance as a biomarker and therapeutic target for primary tumors. Future studies are necessary to elucidate the mechanistic role of CHI3L1 in chordoma immune evasion and to explore targeted interventions that may improve patient outcomes in this aggressive cancer.

Chordomas are primary tumors of the skull base and vertebral column typically derived from the notochord. Treatment options consist of surgical resection, radiotherapy, and chemotherapy. This study reviews clinical trials focused on radiotherapy techniques, such as photon therapy and carbon ion radiotherapy, as well as the concomitant use of radia-tion sensitizers. We completed a literature review on all published clinical trials on the usage of photon, proton, and carbon ion radiotherapy (CIRT) for chordoma in adults and all published literature on radiation sensitizers used for treatment in chordoma from 2000 to 2025. We reviewed all nine current clinical trials on radiotherapy for chordoma in adults. All clinical trials were able to achieve an overall survival rate above 50% at 3-year follow-up. Seven publications were found on the use of radiation sensitizers for chordomas, both in vitro and in vivo. The completed clinical trials evaluate the effectiveness of proton, photon, and CIRT for treatment of the skull base, spine, and sacral chordoma. Current trials continue these efforts and compare the different radiotherapies and determine appropriate doses. Research on radiation sensitizers for chordomas shows various therapies, ranging from hyperthermia to pharmaceutical options, that require further study.

BACKGROUND: Ambiguous destructive lumbosacral tumors with intractable pain and neurological compromise present a dilemma between timely decompression and oncological adequacy. The authors present a rare case of primary unclassified sarcoma of the sacrum to illustrate the implications of diagnostic uncertainty in surgical decision-making. OBSERVATIONS: A 59-year-old woman presented with excruciating low back pain and bilateral sciatica from a destructive lumbosacral mass spanning L5–S4 with circumferential cauda equina compression. CT-guided biopsy demonstrated an atypical epithelioid and spindle cell neoplasm, not otherwise classified. Given rapid neurological decline and refractory pain, she underwent preoperative embolization and urgent posterior decompression with multilevel laminectomies (L4–S4), transpedicular corpectomies (S1–3), and lumbopelvic fixation, followed by paraspinous flap closure. Frozen-section analysis favored a tenosynovial giant cell tumor (TGCT) to support a nerve root–sparing resection. Postoperative MRI showed small residual enhancement at S1–2. Final pathological analysis revealed an intermediate-grade unclassified sarcoma, and she subsequently underwent adjuvant radiation therapy. Systemic staging is ongoing. At the 6-month follow-up, she reported durable analgesia and function. LESSONS: Destructive lumbosacral tumors should be approached with an oncological mindset even when histology is uncertain. In urgent cases, timely decompression and functional preservation may outweigh radical resection, underscoring the value of adaptable, multidisciplinary management. https://thejns.org/doi/10.3171/CASE2646