Chordoma, Rare Spinal Bone Cancer Found to Have Several Genetic Causes

Specific mutations in PI3 kinase signaling genes have been discovered in chordoma, a rare bone cancer with the help of genomic sequencing.

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‘Genomic sequencing has helped find many underlying causes for chordoma, a rare bone cancer, promising new treatment options for a cancer with a poor prognosis.’

Highlights:

Genomic sequencing finds many underlying genetic causes for chordoma, a rare bone cancer
Mutated PI3 kinase signaling genes, an additional copy of the T gene and a new cancer gene called LYST all contribute to develop chordoma
This discovery opens up novel therapeutic options to treat the cancer.

Scientists from the Wellcome Trust Sanger Institute, University College London Cancer Institute and the Royal National Orthopedic Hospital NHS Trust suggest that patients with a rare bone cancer of the skull and spine called chordoma could be helped by existing drugs. This suggestion was made based on the discovery made by scientists that a group of chordoma patients have been found to have mutations in genes that are the target of existing drugs, known as PI3K inhibitors.

This study, the largest genomics study of chordoma to date, has been published in Nature Communications. Following the discovery, the researchers suggest a clinical trial of PI3K inhibitors for this particular group of chordoma patients, who could benefit from existing treatments.

Genomic sequencing was used for the discovery

Whole genome sequencing was used for the first time to gain a better understanding of the biology underlying chordoma. Chordoma tumors from 104 patients revealed that 16 percent of the tumor samples had genetic changes, or mutations, in PI3K signaling genes. PI3K genes can be targeted by existing drugs, known as PI3K inhibitors, which have so far been used to treat many cancers, including breast cancer, lung cancer and lymphoma, but have not yet been considered for chordoma.

Another discovery made through genomic sequencing was the fact that only one additional copy of the gene brachyury, or T, seems to drive these tumors. A new cancer gene specific to chordoma, known as LYST, and not found in any other cancer has also been found.

Dr Sam Behjati, joint first author from the Wellcome Trust Sanger Institute, said: "By sequencing the tumors’ DNA, we get a much clearer view of the genetic changes that drive chordoma. We have shown that a particular group of chordoma patients could be treated with PI3K inhibitors, based on their mutations. This would have been missed had we not done genomic sequencing of their tumors."

Chordoma: Rare Spine Cancer

Chordoma is a rare type of bone cancer that affects the spine anywhere from the base of the skull to the tailbone, causing symptoms of pain, weakness, or numbness in the back, arms, or legs. The tumors are slow-growing, gradually extending into the bone and soft tissue around them; yet they are aggressive and life-threatening. They form in the vertebral bodies of the spine, the sacrum and base of the skull probably developing from persistent embryonic tissue, known as the notochord.

One half of the tumors occur in the base of the spine (sacrum), one third in the base of the skull (occiput), and the rest in the neck, upper back or lower back vertebrae of the spine. The signs and symptoms occurring with this cancer arise due to the growing chordoma that puts pressure on the adjacent areas of the brain or spinal cord.

Chordomas can affect individuals of all ages but typically occur in adults between ages 40 and 70. They are rare and affect approximately 1 per million individuals each year; in the UK they affect 1 in every 800,000 people.

Treatment for the cancer is difficult owing to the involvement of critical structures such as the brainstem, spinal cord, and important nerves and arteries. So far, surgery and radiation are the only effective forms of treatment though they are not foolproof. The tumors often recur after treatment, and also spread in about 40 percent of cases to other areas of the body, such as the lungs.

Future plans for the treatment of chordoma

The findings provide a resource for chordoma research in the future and have opened up three ways of targeting chordoma.

Conducting clinical trials using PI3K inhibitors to target the mutated genes
Developing a therapeutic approach to switch off the extra copy of the T gene
Studying the function of LYST as a cancer gene and its role in the development of the cancer

Josh Sommer, a survivor of chordoma and Executive Director of the Chordoma Foundation, USA, said: "These findings represent a major step forward in understanding the underlying causes of chordoma, and provide hope that better treatments may soon be available for some patients."

Reference:

Patrick S. Tarpey, Sam Behjati, Matthew D. Young, Inigo Martincorena, Ludmil B. Alexandrov, Sarah J. Farndon, Charlotte Guzzo, Claire Hardy, Calli Latimer, Adam P. Butler, Jon W. Teague, Adam Shlien, P. Andrew Futreal, Sohrab Shah, Ali Bashashati, Farzad Jamshidi, Torsten O. Nielsen, David Huntsman, Daniel Baumhoer, Sebastian Brandner, Jay Wunder, Brendan Dickson, Patricia Cogswell, Josh Sommer, Joanna J. Phillips, M. Fernanda Amary, Roberto Tirabosco, Nischalan Pillay, Stephen Yip, Michael R. Stratton, Adrienne M. Flanagan, Peter J. Campbell. The driver landscape of sporadic chordoma. Nature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-01026-0

Source-Medindia