Radiotherapy To Prevent Recurrence Post Brain Tumor Excision: Interview With Matthew Likens, Preside

GT Medical Technologies, a company based in Arizona, has developed the FDA-approved GammaTile system, which can provide localized radiation therapy for brain tumor excision sites. Its goal is to reduce tumor recurrence and enhance patient survival. The treatment consists of radiation seeds encased in a collagen substrate. These are easy to place at the excision site with a minimum of effort at the end of a surgical procedure.

Unfortunately, brain tumor recurrence is relatively common, and so treatments that can help to reduce this phenomenon, while sparing healthy tissues and reducing side effects, are very welcome. The localized delivery possible with the GammaTiles helps to reduce side-effects, such as hair loss, while their 3D structure allows them to be placed within the excision site so as to maximally target residual tumor cells and spare nearby healthy tissue.

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The tiles do not continue to emit radiation indefinitely, and as much as 90% of the radiation is emitted by 33 days after implantation. The radiation is considered to be depleted by 100 days following implantation.

Medgadget had the opportunity to talk with Matthew Likens, president and CEO of GT Medical Technologies, to learn more about the GammaTile system.

Conn Hastings, Medgadget: Please give us an overview of the challenges of treating brain tumors, and in particular recurring brain tumors.

Matthew Likens, GT Medical Technologies: Approximately 700,000 Americans are living with some type of brain tumor at any given time, and there are more than 120 varieties of tumors. Outcomes for patients with brain tumors have improved little over the past 30 years, offering little hope to people facing this devastating prognosis. Brain tumor recurrence is common, and about half of all patients treated for brain tumors have their disease recur within a year, often quickly and aggressively. After decades of seeking better treatment options for patients with brain tumors, GT Medical Technologies, Inc. was founded by brain tumor specialists in 2017 with a purpose of improving the lives of patients with brain tumors.

Many patients with recurrent brain tumors have received levels of radiation therapy that make the risk of additional radiation outweigh potential benefits. Consequently, these patients are left with surgery as their only option, and tumor removal surgery alone without adjuvant radiation therapy almost guarantees rapid recurrence of tumors. GammaTile Therapy creates an option for patients who may not be candidates for other forms of radiation therapy and begins targeting residual tumor cells with radiation right away. This approach is proven to delay recurrence and potentially extend survival for patients who had previously run out of options.

Medgadget: What are the limitations of conventional brachytherapy in this context?

Matthew Likens: Traditional brachytherapy has proven to be quite useful for patients with prostate cancer. Its previous use in the brain has typically been with either individual bare seeds being placed or by placing braided or stranded seeds throughout the cavity created by removing the tumor. These approaches can add between 30-45 minutes to the length of the surgical procedure and are not effective at protecting remaining healthy brain tissue. GammaTiles are designed with a collagen carrier in which the brachytherapy seeds are embedded. The collagen carriers not only provide a structural offset that protects remaining healthy brain tissue but allows for efficient placement, typically taking less than five minutes at the end of tumor resection procedures.

Medgadget: How does GammaTile therapy work and how is it administered?

Matthew Likens: GammaTile Therapy is an FDA-cleared, Surgically Targeted Radiation Therapy (STaRT) for patients with newly diagnosed malignant tumors and recurrent intracranial neoplasms (brain tumors), including primary (benign or malignant) and metastatic tumors. The small, bioresorbable, conformable 3D-collagen tile is placed directly at the site of the tumor immediately after the tumor is removed, providing a dose-intense treatment at the completion of resection to target residual tumor cells before they can replicate.

Medgadget: What are the advantages of the treatment, and how does it compare with conventional brachytherapy?

Matthew Likens: One of the major advantages of GammaTile Therapy is that GammaTiles are implanted during the last five minutes of surgery and typically represent all the radiotherapy patients require. Thus, no additional trips to the hospital or clinic for radiation therapy are required, saving these vulnerable patients from multiple health care facility exposures. GammaTile is extremely targeted and was specifically designed to protect healthy brain tissue. Additionally, GammaTiles are designed to limit side effects — including hair loss — because radiation therapy is delivered locally. This therapy also has excellent reimbursement coverage by CMS and private insurers so treatment economics are favorable for adopting institutions.

Additionally, the standard of care for brain tumors is surgery followed by External Beam Radiation Therapy, in which treatment with radiation beams is delivered from outside the body inward. This often requires outpatient radiation treatments 5x/week for up to six weeks. Typical radiation involves a 2-4 week waiting period before a patient can begin EBRT after surgery because it takes time for surgery wounds to heal. GammaTile Therapy removes this waiting period, with a solution that begins targeting residual cells immediately, before those cells have the chance to replicate.

Medgadget: How does the treatment help to spare healthy tissue from the effects of the radiation?

Matthew Likens: GammaTile Therapy is designed to protect healthy brain tissue because of the structural offset created by embedding radiation seeds within each collagen carrier. This design facilitates rapid, accurate placement following the brain tumor removal procedure to deliver a predictable dose of radiation in a surgically targeted way. The radiation dose emitted by GammaTile is delivered to a localized area and is highly lethal to residual tumor cells. Ninety percent of the radiation dose is delivered in 33 days. After 100 days, GammaTile radiation sources are considered completely free of radiation.

Medgadget: How does GammaTile Therapy affect patients, in terms of survival, convenience, and side-effects?

Matthew Likens: Overall, patient survival has improved with GammaTile Therapy with complication rates equal to or less than existing treatments in patients with recurrent, previously irradiated brain tumors. This most recent data was presented at the American Association of Neurological Surgeons 2019 Annual Scientific Meeting, which also demonstrated that GammaTile Therapy exhibited excellent local control at the surgical site. Regarding convenience, since GammaTiles are implanted at the end of surgery, no additional trips to the hospital or clinic for radiation therapy are required. This alleviates the burden of treatment on patients and their caregivers.

Additional data published in the Journal of Neurosurgery (JNS) demonstrates that GammaTile Therapy is a safe and effective new option proven to delay tumor progression in patients with previously treated, aggressive brain tumors known as meningiomas, the most common type of primary brain tumor. Taken as a whole group of brain tumor types, patients treated with surgery followed by GammaTile Therapy had an approximately 2x improvement in median time to tumor recurrence compared to their most recent prior treatment at the same location.

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