Chordoma Foundation

GI-6301 + radiation

Clinical trial of GI-6301 (yeast-brachyury vaccine) versus placebo in combination with radiotherapy in locally advanced, unresectable chordoma


Researchers at the National Cancer Institute in Bethesda, Maryland, are now enrolling patients in a Phase 2 clinical trial evaluating whether a therapeutic vaccine called GI-6301 given in combination with radiation is more effective than radiation alone in causing tumor regression or preventing tumor progression.

The trial is designed specifically for chordoma patients 18 years and older with inoperable tumor, residual tumor following surgery, or locally recurrent tumor who are planning to have radiation.

Why this trial is being done

Radiotherapy is a standard treatment option for chordoma patients with residual or inoperable tumor. However, the majority of chordomas that are not fully resected will eventually progress after radiation. Research in other cancers suggests that the combination of radiation plus therapies that stimulate the immune system can have powerful antitumor effects. Therefore, in this trial, researchers are seeking to determine whether stimulating the immune system to target chordoma in combination with radiation can cause tumor shrinkage and/or prevent further tumor growth to a greater degree than radiation alone.

Specifically, this trial will test the therapeutic vaccine GI-6301, which is designed to stimulate the immune system to attack chordoma. Therapeutic vaccines are meant to help the immune system fight disease more effectively, as opposed to prophylactic vaccines (like the flu shot) which help to prevent disease. GI-6301 works by generating immunity against a protein called brachyury, which is found on most chordoma tumors but is absent from nearly all normal tissues. In other words, GI-6301 trains the immune system to attack chordoma but not healthy parts of the body.

A recently completed Phase 1 trial of GI-6301 demonstrated that the vaccine could be delivered safely. It also showed that the vaccine was capable of inducing immune responses against brachyury in chordoma patients. Of the eight chordoma patients whose tumors were growing when they entered the Phase 1 trial, five stopped growing and one shrunk by more than 30 percent while in the study.

Who can participate

The trial is designed specifically for chordoma patients who are at high risk of tumor regrowth following radiation, including:

  • Patients who have residual tumor remaining after surgery
  • Newly diagnosed patients who are unable to have surgery
  • Patients who have a local recurrence following previous surgery

Patients must meet the following basic criteria to be eligible:

  • Confirmed diagnosis of chordoma
  • Localized (no evidence of metastases) and inoperable tumor
  • Age 18 years or older
  • At least 1cm of tumor measurable on imaging
  • Able to receive at least 50 GyE of radiation to the tumor
  • No major laboratory abnormalities
  • No history of autoimmune disease
  • No allergy to yeast
  • Willing and able to travel to the National Cancer Institute (NCI) in Bethesda, MD for treatment and follow-up visits

Full eligibility criteria can be found on and on the NCI website.

How the trial will work

The trial is taking place at the National Institutes of Health Clinical Center in Bethesda, MD. The NCI will pay for transportation costs (including airfare) within the US and a portion of lodging costs for patients enrolled in this trial.

Participants in the trial will initially be randomized to receive radiation plus the vaccine, or radiation plus a blinded placebo. Those who receive radiation plus placebo will have the option to “cross-over” and begin receiving the vaccine if their tumor grows while on the study. This means that everyone who enters the study will be given the opportunity to receive the vaccine if radiation alone is not stopping the growth of the tumor.

The process of participating in the trial is as follows:

  • Patients travel to NIH to receive injections of the vaccine (or placebo) every 2 weeks for 3 doses prior to starting radiation (approximately 4 weeks).
  • Patients then complete radiation treatment with their home radiation oncologist (typically over a 1-2 month timespan).
  • Following completion of radiation, patients travel back to NIH to resume injections every 2 weeks for 3 more doses (approximately 6 weeks).
  • Doses then spread out to every 4 weeks for 4 doses, and then 1 dose every 3 months. This schedule is continued until disease progression.

Between all doses of vaccine, patients may return home and travel back for the next visit. There is no requirement to stay locally in Bethesda at any point in the study outside of clinic visits and dosing days.

Repeat imaging studies will be performed about 3 months after completion of radiation and then every 3 months for the first year, every 6 months for the second year, and yearly thereafter. Scans can be done earlier if new symptoms develop between scheduled scans.

How to enroll

To enroll in this study, patients or their doctors can contact the principal investigator, Deric Park, MD, at, or Christine Bryla, RN, at



If you have more questions about this trial or other clinical trials that may be options for chordoma patients, please contact a Chordoma Foundation Patient Navigator.

Contact a CF Patient Navigator

Learn more about immunotherapy

From the National Cancer Institute

From the Chordoma Foundation

Dr. Chris Heery discusses immune therapy at a Chordoma Community Conference

Dr. Peter Wettstein discusses immunotherapy for chordoma at a Chordoma Community Conference


Medical information provided by the Chordoma Foundation in any medium is for informational and educational purposes only. After reading content from the Chordoma Foundation, review the information carefully with your physician. Information from the Chordoma Foundation is not a substitute for consultations with qualified health care professionals who are familiar with your medical conditions and needs. The Chordoma Foundation strongly recommends that care and treatment decisions be made in consultation with your physician or other qualified health care professionals who are familiar with your specific health situation.

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