Notochordal Tumors: An Update on Molecular Pathology with Therapeutic Implications

Recent molecular investigations of chordoma show common expression of various receptor tyrosine kinases and activation of downstream signaling pathways contributing to tumor growth and progression. The transcription factor brachyury (also known as T) is important in notochord differentiation, and germline duplication of the gene is often found in familial chordomas. Nuclear expression of brachyury is consistent in chordoma and in benign notochordal cell tumor. Based on the molecular evidence, targeting of several kinds of molecular agents has been attempted for the treatment of uncontrolled chordomas and achieved partial response or stable condition in many cases.

Targeted therapies for soft-tissue sarcomas

The past several decades have revealed certain challenges that are inherent to soft-tissue sarcomas with regards to devising, testing and setting treatment paradigms for such a rare and heterogeneous malignancy. Despite this, significant advances have been made through the efforts of scientists, clinicians and patients alike. We are now entering a molecular era of cancer and current biotechnology is beginning to unravel the pathogenic enigma of these often devastating tumors. As our understanding of these malignancies improves, so does our list of potential treatment options. The impetus now lies with the medical/scientific community to direct translational research and subsequently the development and clinical testing of novel compounds in a fashion that best serves this unique patient population. To do so, we must continue to integrate the lessons of the past with the resources and promise of the future. This review will outline current areas of therapeutic interest in soft-tissue sarcomas with regard to agents that have reached clinical testing.

Three-level en bloc spondylectomy for chordoma

BACKGROUND

En bloc resection of spinal and sacral chordomas may convey a survival benefit. However, these procedures often are complex and require the surgeon to plan a procedure that results in negative tumor margins, protects vital neurovascular structures, and concludes with a viable biomechanical reconstruction.

OBJECTIVE

We present a case of a 3-level en bloc lumbar spondylectomy and reconstruction.

METHODS

A case of a 45-year-old woman with biopsy-proven exophytic L4 chordoma is presented. The patient underwent successful L3-L5 en bloc spondylectomy and reconstruction over 3 stages.

RESULTS

The patient did well following the procedure, and was neurologically intact at 6-week follow-up.

CONCLUSION

Three-level en bloc spondylectomy with lumbopelvic reconstruction is a challenging yet feasible procedure.

Durable complete response to chemotherapy in an infant with a clival chordoma

Chordomas are rare bone tumors of notochord remnants that may occur anywhere within the axial skeleton. The standard of care is complete surgical removal. Proton beam irradiation is commonly used when the tumor is inaccessible or has recurred. Chemotherapy has been used in the treatment of patients at relapse but it has been generally proven ineffective. We report a 7-month-old infant with a clival chordoma who responded to combination chemotherapy consisting of cycles of vincristine/cyclophosphamide/doxorubicin alternating with etoposide/ifosfamide. She has been off chemotherapy for 2 years and is well at age 5.

Phase II study of imatinib in advanced chordoma

PURPOSE

To explore the antitumor activity of imatinib in patients with advanced platelet-derived growth factor β (PDGFB)/PDGF receptor β (PDGFRB)-positive chordomas.

PATIENTS AND METHODS

In a collaborative Italian-Swiss, prospective, phase II clinical study conducted from November 2004 through April 2006, 56 patients with advanced PDGFB and/or PDGFRB chordoma received 800 mg/d of imatinib until progression. The primary end point was the overall tumor response rate (ORR), defined by RECIST. Secondary, exploratory end points included tissue response (ie, changes in tumor density or signal intensity/contrast enhancement, and/or [18F]-fluorodeoxyglucose positron emission tomography [PET] uptake), overall survival, progression-free survival (PFS), and pain score.

RESULTS

Among 50 patients evaluable by RECIST, the best response was one partial response (PR) obtained at 6 months (ORR, 2%). There were 35 patients with stable disease (SD, 70%) and a 64% clinical benefit rate (ie, RECIST complete response + PR + SD ≥ 6 months). A minor dimensional response (< 20%) was detected in nine patients. A maximum standard uptake value decrease ≥ 25% was observed in 10 (39%) of 26 patients evaluable for PET response at 3 months. Changes in the Brief Pain Inventory score were consistent with the response assessment. Median PFS (intention-to-treat population, 56 patients) was 9 months. No unexpected toxicities were observed.

CONCLUSION

This is the largest phase II study in chordoma to date. It confirms anecdotal evidence that imatinib has antitumor activity in this orphan disease, and therefore, it is worth further investigation.

Chordoma of the sacrum and vertebral bodies

Chordomas are relatively rare tumors of bone. These primary malignant lesions occur throughout the spinal column and often show advanced growth at the time of diagnosis. Because such tumors are minimally responsive to radiation and chemotherapy, surgical resection is the mainstay of treatment. Patient survival and local control are associated with the ability to achieve wide surgical margins during excision. However, surgical morbidity may be substantial given the propensity for chordomas to abut or surround neural, vascular, and visceral structures. Thus, early recognition is essential, and treatment by a multidisciplinary team is ideal.

Chordoma

PURPOSE OF REVIEW

To review developments in chordoma treatment.

RECENT FINDINGS

Recent series with prolonged follow-up show that adequate margins are necessary for surgery to be curative. Safe margins are often difficult to obtain due to the anatomical sites of chordoma: sacrum, skull base and spine. Tumors in these sites are problematic for radiation therapy as well, and this adds to the need for high doses. Hadrons have therefore been used in addition to, or instead of, photons. New photon beam techniques, e.g. intensity modulated radiation therapy and stereotactic procedures, have recently been evaluated. Although less available than photons, hadrons possess certain advantages. While chemotherapy is poorly active, recent interest has focused on molecular-targeted agents. Imatinib was shown to be active, providing mainly nondimensional tissue responses in a significant proportion of patients, which may improve symptoms and progression-free interval. Epidermal growth factor receptor targeting, anti-angiogenics, and the combination of targeted agents with chemotherapy and radiation therapy are also under scrutiny.

SUMMARY

Two major issues about local treatment remain unresolved: when to complement surgery with radiation therapy, and how best to deliver high doses of radiation therapy to the tumor tissue. Regarding systemic treatment, there is ongoing research into how to exploit molecular-targeted therapies.

American Society of Clinical Oncology 41st annual meeting

For many years the annual meeting of the American Society of Clinical Oncology (ASCO) has been the premier meeting in clinical oncology, and one that is closely scrutinised by Wall Street and international investors because of the economic significance of cancer therapies to the pharmaceutical and biotechnology industries. The area of biologicals and targeted therapies exploded in the late 1990s after the blockbuster results with the monoclonal antibody rituximab in the treatment of lymphoma. Although historically a somewhat conservative organisation that is still closely tied to classical cytotoxic chemotherapy, ASCO has been able to integrate various areas of biological therapy into its scope of clinical activity. Although ASCO still has 'American' in its title, it is really the 'International' Society of Clinical Oncology, as reflected by the attendance at this year's meeting by approximately 30,000, with approximately two-thirds attending from outside the US. There were 9708 abstracts published in conjunction with the meeting, 86 of which are referenced in this review. There were 10 papers chosen for plenary presentations and many other key papers were presented at other oral abstract sessions and poster discussion session that were organised by tumour type. In addition to key papers submitted by specific tumour type, for this year's meeting there were 103 abstracts published in the session entitled 'Developmental Therapeutics: Immunotherapy', and 218 in the session entitled Developmental Therapeutics: Molecular Targets', for a total of 321 biological therapy abstracts compared with only 125 abstracts for the session entitled 'Developmental Therapeutics: Cytotoxic Therapy'. This meeting review is organised by biotherapy modality rather than tumour type.