On the surface of our cells are proteins that act like antennas, receiving signals that tell the cell when to grow and divide. One of these is the Epidermal Growth Factor Receptor, or EGFR. In some cancers, these receptors are overactive, causing cells to multiply uncontrollably, which has led to targeted therapies designed to interfere with this process.
An advanced approach is radioimmunotherapy, which combines targeted therapy with radiation to deliver it directly to cancer cells while largely sparing healthy tissues. EGFR I-131 therapy is a specific type of this treatment that uses a molecule to find cells with the EGFR protein and deliver a radioactive substance to them.
The Mechanism of EGFR 131 Therapy
The effectiveness of EGFR I-131 therapy lies in its two-part design. The first component is a monoclonal antibody, a man-made protein engineered to recognize and bind exclusively to the EGFR protein on the surface of cancer cells. This high specificity guides the treatment directly to the tumor.
The second component is the radioactive payload, Iodine-131 (I-131). I-131 is a radioisotope, an unstable version of iodine that releases energy as radiation potent enough to kill cells. Before treatment, the I-131 is chemically attached to the monoclonal antibody.
When this combination drug is introduced into the patient’s body, the antibody circulates until it finds and locks onto the EGFR proteins. Once attached, the I-131 emits beta radiation. This radiation travels a very short distance, damaging the DNA of the cancer cell it is attached to and causing it to die.
A significant aspect of this mechanism is the “bystander effect.” The radiation released can penetrate and kill not only the cell it is directly attached to but also several neighboring cancer cells. This is useful in tumors where not every cell might have the EGFR target, ensuring a more comprehensive attack on the cancer.
Cancers Treated with EGFR 131
This targeted therapy is investigated for cancers known to have high levels of EGFR, as the treatment’s success depends on this target. A first step is to test a sample of the patient’s tumor tissue. If the cells show an overexpression of EGFR, the patient may be a candidate.
A significant area of research for EGFR I-131 therapy is in treating aggressive brain tumors, most notably glioblastoma. These cancers are difficult to treat with conventional methods because of their location and resistance. The ability of radioimmunotherapy to specifically seek out cancer cells makes it an appealing option for these cases.
Beyond brain tumors, this therapy has been studied in other types of cancer where EGFR overexpression is common. Clinical trials have explored its use in treating certain types of head and neck cancers and non-small cell lung cancer. It is often considered for patients with advanced disease or for those whose cancer has not responded to other treatments.
This therapy is not a first-line treatment for most cancers. Its application is highly specific and reserved for situations where the tumor has the correct molecular target and other therapies may be less effective.
The Treatment Process and Patient Experience
The process for a patient begins with a thorough evaluation to confirm eligibility, including a general health assessment. Once a patient is cleared, the treatment is administered in a controlled hospital environment.
The therapy is given through an intravenous (IV) infusion. The radioactive drug is slowly dripped into the bloodstream, a process that is generally painless. During and after the infusion, the patient is monitored for any immediate reactions.
A part of the process involves verifying that the treatment has reached its target. Shortly after the infusion, patients undergo imaging scans, such as a SPECT/CT. These scans detect the radiation from the I-131, allowing the medical team to see where the drug has accumulated and confirm it has targeted the tumor.
Because the treatment involves a radioactive substance, patients are required to stay in a special, isolated hospital room for a few days. This is a safety measure to prevent radiation exposure to others. The length of the stay depends on how quickly the patient’s body clears the unabsorbed radioactive material.
Managing Side Effects and Safety Precautions
Following treatment, patients are monitored for potential side effects. The infusion itself can cause reactions, and the EGFR-targeting antibody may lead to a skin rash. Because the therapy involves radiation, it can also cause fatigue and may affect the bone marrow, leading to a temporary decrease in blood cell counts. These effects are managed with supportive care and medication.
A unique aspect of this therapy involves radiation safety. For a period after leaving the hospital, the patient’s body will still contain small amounts of radioactive material, which is excreted through bodily fluids. To protect family and friends from radiation exposure, patients must follow specific precautions.
These safety measures are temporary but strict. They often include maintaining a safe distance from other people, especially pregnant women and young children, for one to two weeks. Patients will also be instructed to use a separate bathroom if possible, flush the toilet twice, and practice good hygiene by not sharing personal items. The medical team provides detailed guidance on these precautions.